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David Stanley - One of the best experts on this subject based on the ideXlab platform.
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Insect prostaglandins and other Eicosanoids: From molecular to physiological actions
Advances in Insect Physiology, 2020Co-Authors: David StanleyAbstract:Abstract In this essay we provide a comprehensive update on the biology and molecular biology of prostaglandins (PGs) and other Eicosanoids in insects. Phospholipase A2 (PLA2) is the first biochemical step in eicosanoid biosynthesis. Cellular and secretory PLA2 types, similar to those of vertebrates, have been identified and demonstrated to act in insect eicosanoid biosynthesis. However, eicosanoid biosynthetic pathways in insects are not identical to those of vertebrates. The relatively low concentrations of arachidonic acid (AA) in phospholipids of insect tissues suggest that PLA2 may hydrolyse linoleic acid as a precursor of eicosanoid biosynthesis and its subsequent desaturation and elongation leads to AA. Unlike vertebrates, AA is not oxidized by cyclooxygenase, but by a specific peroxidase called peroxinectin to produce a prostaglandin (PG) precursor, PGH2, which is then isomerized into PGE2 by PGE2 synthase. PGs and other Eicosanoids mediate insect reproduction such as oocyte development and egg-laying behaviour, trehalose metabolism, fluid secretion, and immunity. They also interact with insect cytokine and other immune mediators to propagate non-self recognition signals to immune effector tissues. In the cross-talks, Eicosanoids act as downstream signals because any intervention of eicosanoid signalling leads to substantial immunosuppression. Because host immunosuppression favours pathogens, some entomopathogens exploit a PLA2 inhibitory strategy to express their virulence. We propose PGs and other Eicosanoids as central signalling systems in insect biology.
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Eicosanoids in insect immune signal transduction
Advances in Experimental Medicine and Biology, 2020Co-Authors: David Stanley, Ralph W. HowardAbstract:Eicosanoid is a collective term for all biologically active, oxygenated metabolites of arachidonic acid and two other C20 polyunsaturated fatty acids. There are three major groups of Eicosanoids. The prostaglandins (PGs), so named because they were first discovered in seminal fluids originating in the prostate gland, are products of the cyclooxygenase pathways. The cytochrome P450 “epoxygenase pathways” yield the epoxyeicosatrienoic acids. Various lipoxygenase pathways are responsible for biosynthesizing a wide range of compounds, including leukotrienes and hydroxyeicosatetraenoic acids. The biosynthesis and structures of representatives of the major groups of Eicosanoids are outlined in Figure 1, and described in detail elsewhere (Stanley, 1999). One or more members of the major eicosanoid groups have been detected in virtually all mammalian tissues and body fluids, where they serve as lipid mediators of cellular events. Among their important actions, Eicosanoids modulate ion transport physiology, mediate contraction or relaxation of smooth muscles and exert tremendous influence in host defense mechanisms. It would be difficult to exaggerate the importance of Eicosanoids in the vertebrate immune system. Sir John Vane shared in the 1982 Nobel Prize in Medicine or Physiology, which recognized his discovery that the analgesic effects of aspirin are due to inhibition of prostaglandin biosynthesis. This discovery launched a very large pharmaceutical research enterprise aimed at discovery of new non-steriodal anti-inflammatory drugs, all of which act through their inhibitory influence on prostaglandin biosynthesis.
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prostaglandins and other Eicosanoids in insects biosynthesis and biological actions
Frontiers in Physiology, 2019Co-Authors: David StanleyAbstract:This essay reviews the discoveries, synthesis and biological significance of prostaglandins (PGs) and other Eicosanoids in insect biology. It presents the most current – and growing – understanding of the insect mechanism of PG biosynthesis, provide an updated treatment of known insect phospholipase A2 (PLA2), and detail contemporary findings on the biological roles of PGs and other Eicosanoids in insect physiology, including reproduction, fluid secretion, hormone actions in fat body, immunity and eicosanoid signaling and cross-talk in immunity. It completes the essay with a prospectus meant to illuminate research opportunities for interested readers. In more detail, cellular and secretory types of PLA2, similar to those known on the biomedical background, have been identified in insects and their roles in eicosanoid biosynthesis documented. It highlights recent findings showing that eicosanoid biosynthetic pathway in insects is not identical to the solidly established biomedical picture. The relatively low concentrations of arachidonic acid (AA) present in insect phospholipids (< 0.1% in some species) indicate that PLA2 may hydrolyze linoleic acid (LA) as a precursor of eicosanoid biosynthesis. The free LA is desaturated and elongated into AA. Unlike vertebrates, AA is not oxidized by cyclooxygenase, but by a specific peroxidase called peroxinectin to produce PGH2, which is then isomerized into cell-specific PGs. In particular, PGE2 synthase recently identified converts PGH2 into PGE2. In the cross-talks with other immune mediators, Eicosanoids act as downstream signals because any inhibition of eicosanoid signaling leads to significant immunosuppression. Because host immunosuppression favors pathogens and parasitoids, some entomopathogens evolved a PLA2 inhibitory strategy activity to express their virulence.
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Eicosanoid-mediated immunity in insects
Developmental and Comparative Immunology, 2017Co-Authors: Shabbir Ahmed, David Stanley, Chunju AnAbstract:Abstract Eicosanoid is a collective term for oxygenated metabolites of C20 polyunsaturated fatty acids. As seen in mammals, Eicosanoids play crucial roles in mediating various physiological processes, including immune responses, in insects. Upon microbial pathogen infection, non-self recognition signals are propagated to nearly immune effectors such as hemocytes and fat body using various immune mediators, in which eicosanoid signals act as the ultimate downstream mediator. The chemical diversity of Eicosanoids may operate to mediate various immune responses. Some entomopathogenic bacteria suppress eicosanoid biosynthesis, which inhibits host insect immunity and promotes their pathogenicity. This review introduces immune responses mediated by various Eicosanoids. Then it explains the cross-talks of Eicosanoids with other immune mediators including cytokines, biogenic monoamines, and nitric oxide to clarify the complexity of insect immune mediation. Finally, we highlight the biological significance of Eicosanoids by demonstrating bacterial pathogenicity inhibiting a key enzyme – phospholipase A 2 – in eicosanoid biosynthesis using their secondary metabolites to defend host insect immune attack.
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nitric oxide mediates insect cellular immunity via phospholipase a2 activation
Journal of Innate Immunity, 2017Co-Authors: David StanleyAbstract:After infection or invasion is recognized, biochemical mediators act in signaling insect immune functions. These include biogenic amines, insect cytokines, Eicosanoids, and nitric oxide (NO). Treating insects or isolated hemocyte populations with different mediators often leads to similar results. Separate treatments with an insect cytokine, 2 biogenic amines, and an eicosanoid lead to a single result, hemocyte spreading, understood in terms of intracellular cross-talk among these signaling systems. This study focuses on the cross-talk between NO and eicosanoid signaling in our model insect, Spodoptera exigua. Bacterial injection increased NO concentrations in the larval hemocytes and fat body, and RNA interference (RNAi) of the S. exigua NO synthase (NOS) gene suppressed NO concentrations. RNAi treatment also led to a significant reduction in hemocyte nodulation following bacterial injection. Similar RNAi treatments led to significantly reduced PLA2 activities in the hemocytes and fat body compared to control larvae. Injection of L-NAME also prevented the induction of PLA2 activity following bacterial challenge. An injected NO donor, S-nitroso-N-acetyl-DL-penicillamine, increased PLA2 activity in a dose-dependent manner. However, Eicosanoids did not influence NO concentrations in immune-challenged larvae. We infer that NO and eicosanoid signaling operate via cross-talk mechanisms in which the elevated NO concentrations activate PLA2 and eicosanoid biosynthesis, which finally mediates various immune responses.
Kemal Buyukguzel - One of the best experts on this subject based on the ideXlab platform.
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Inhibition of eicosanoid signaling leads to increased lipid peroxidation in a host/parasitoid system
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2016Co-Authors: Ender Büyükgüzel, Hasan Tunaz, Meltem Erdem, Ceyhun Küçük, Utku Can Atılgan, David Stanley, Kemal BuyukguzelAbstract:Abstract We posed the hypothesis that inhibition of eicosanoid biosynthesis leads to increased lipid peroxidation in insects. Here we report that rearing the greater wax moth, Galleria mellonella , on media supplemented with selected inhibitors of eicosanoid biosynthesis throughout the larval, pupal and adult life led to major alterations in selected oxidative and antioxidative parameters of wax moth and its ectoparasitoid, Bracon hebetor . The highest dietary dexamethasone (Dex), esculetin (Esc) and phenidone (Phe) led to increased malondialdehyde (MDA) levels and to elevated catalase (CAT) and glutathione-S-transferase (GST) activities in all developmental stages of host larvae. Dietary Phe resulted in increased MDA levels, and CAT activity in G. mellonella adults by about 4-fold and about 2-fold, respectively. The Phe effect on GST activity in all stages of the wax moth was expressed in a dose-dependent manner, increased to 140 nmol/mg protein/min in larvae. MDA levels were increased by over 30-fold in adult wasps reared on Dex- and Esc-treated hosts. CAT and GST activities were increased in adult parasitoids reared on Esc-and Phe-treated hosts. GST activity of Dex-treated parasitoid larvae increased from about 4 to over 30 nmol/mg protein/min. Dietary Phe led to increased GST activity, by about 25-fold, in adult wasps. These data indicate that chronic inhibition of eicosanoid biosynthesis leads to increased oxidative stress, strongly supporting our hypothesis. The significance of this work lies in understanding the roles of Eicosanoids in insect biology. Aside from other well-known Eicosanoids actions, we propose that Eicosanoids mediate reductions in oxidative stress.
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the influence of chronic eicosanoid biosynthesis inhibition on life history of the greater waxmoth galleria mellonella and its ectoparasitoid bracon hebetor
Journal of Insect Physiology, 2011Co-Authors: Ender Büyükgüzel, Hasan Tunaz, David Stanley, Kemal BuyukguzelAbstract:Abstract Eicosanoids are oxygenated metabolites of three C20 polyunsaturated fatty acids, mainly arachidonic acid (AA; 20:4n-6), but also 20:3n-6 and 20:5n-3. Aside from their importance in biomedicine, Eicosanoids act in invertebrate biology. Prostaglandins (PGs) influence salt and water transport physiology in insect rectal epithelia and in Malpighian tubules. PGs also influence a few insect behaviors, including releasing oviposition behavior and behavioral fever. Eicosanoids act in ovarian development and in insect immunity. Because Eicosanoids act in several areas of insect biology, we posed the hypothesis that chronic inhibition of eicosanoid biosynthesis, in the absence of microbial challenge, can influence insect life table parameters, including developmental time, survival, adult longevity and parasitoid fecundity. Here we report that inhibiting eicosanoid biosynthesis throughout the larval life exerted minor influences on some life table parameters of the greater wax moth, Galleria mellonella and its ectoparasitoid, Bracon hebetor, however, the inhibitors strongly reduced the production and hatchability of the parasitoids’ eggs. The significance of the work relates to the potentials of understanding and targeting eicosanoid systems as a platform for developing new technologies of insect pest management. As seen here, the impact of targeting eicosanoid systems is seen in crucial moments of insect life histories, such as reproduction or immune challenge rather than in overall larval development.
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The influence of chronic eicosanoid biosynthesis inhibition on life history of the greater waxmoth, Galleria mellonella and its ectoparasitoid, Bracon hebetor
Journal of Insect Physiology, 2011Co-Authors: Ender Büyükgüzel, Hasan Tunaz, David Stanley, Kemal BuyukguzelAbstract:Eicosanoids are oxygenated metabolites of three C20 polyunsaturated fatty acids, mainly arachidonic acid (AA; 20:4n-6), but also 20:3n-6 and 20:5n-3. Aside from their importance in biomedicine, Eicosanoids act in invertebrate biology. Prostaglandins (PGs) influence salt and water transport physiology in insect rectal epithelia and in Malpighian tubules. PGs also influence a few insect behaviors, including releasing oviposition behavior and behavioral fever. Eicosanoids act in ovarian development and in insect immunity. Because Eicosanoids act in several areas of insect biology, we posed the hypothesis that chronic inhibition of eicosanoid biosynthesis, in the absence of microbial challenge, can influence insect life table parameters, including developmental time, survival, adult longevity and parasitoid fecundity. Here we report that inhibiting eicosanoid biosynthesis throughout the larval life exerted minor influences on some life table parameters of the greater wax moth, Galleria mellonella and its ectoparasitoid, Bracon hebetor, however, the inhibitors strongly reduced the production and hatchability of the parasitoids' eggs. The significance of the work relates to the potentials of understanding and targeting eicosanoid systems as a platform for developing new technologies of insect pest management. As seen here, the impact of targeting eicosanoid systems is seen in crucial moments of insect life histories, such as reproduction or immune challenge rather than in overall larval development. © 2011 Elsevier Ltd.
Ender Büyükgüzel - One of the best experts on this subject based on the ideXlab platform.
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Inhibition of eicosanoid signaling leads to increased lipid peroxidation in a host/parasitoid system
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2016Co-Authors: Ender Büyükgüzel, Hasan Tunaz, Meltem Erdem, Ceyhun Küçük, Utku Can Atılgan, David Stanley, Kemal BuyukguzelAbstract:Abstract We posed the hypothesis that inhibition of eicosanoid biosynthesis leads to increased lipid peroxidation in insects. Here we report that rearing the greater wax moth, Galleria mellonella , on media supplemented with selected inhibitors of eicosanoid biosynthesis throughout the larval, pupal and adult life led to major alterations in selected oxidative and antioxidative parameters of wax moth and its ectoparasitoid, Bracon hebetor . The highest dietary dexamethasone (Dex), esculetin (Esc) and phenidone (Phe) led to increased malondialdehyde (MDA) levels and to elevated catalase (CAT) and glutathione-S-transferase (GST) activities in all developmental stages of host larvae. Dietary Phe resulted in increased MDA levels, and CAT activity in G. mellonella adults by about 4-fold and about 2-fold, respectively. The Phe effect on GST activity in all stages of the wax moth was expressed in a dose-dependent manner, increased to 140 nmol/mg protein/min in larvae. MDA levels were increased by over 30-fold in adult wasps reared on Dex- and Esc-treated hosts. CAT and GST activities were increased in adult parasitoids reared on Esc-and Phe-treated hosts. GST activity of Dex-treated parasitoid larvae increased from about 4 to over 30 nmol/mg protein/min. Dietary Phe led to increased GST activity, by about 25-fold, in adult wasps. These data indicate that chronic inhibition of eicosanoid biosynthesis leads to increased oxidative stress, strongly supporting our hypothesis. The significance of this work lies in understanding the roles of Eicosanoids in insect biology. Aside from other well-known Eicosanoids actions, we propose that Eicosanoids mediate reductions in oxidative stress.
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effects of eicosanoid biosynthesis inhibitors on selected oxidative stress biomarkers in the midgut of galleria mellonella lepidoptera pyralidae larvae
Journal of Entomological Science, 2014Co-Authors: Ender BüyükgüzelAbstract:Abstract Eicosandoids, or icosanoids, are signaling compounds created by the oxidation of 20-carbon fatty acids. They control many complex physiological and immunological functions in vertebrate and invertebrate animals. This study tested the hypothesis that Eicosanoids act in insect antioxidant defense. The effects of 3 eicosanoid biosynthesis inhibitors (EBIs) – dexamethasone, esculetin, and phenidone – on the oxidative stress indicator, malondialdehyde (MDA), and the detoxification enzyme, glutathione S-transferase (GST), was examined in the midgut of larvae of the greater wax moth, Galleria mellonella (L.). The larvae were reared on artificial diets supplemented with 0.001, 0.01, 0.1 or 1.0% of the EBIs. Esculetin, which is a lipoxygenase inhibitor, significantly increased MDA content; whereas, GST activity was significantly increased at only the highest concentration tested. Dexamethasone, a phospholipase A2 inhibitor, significantly increased MDA content and GST activity at concentrations of 0.01, 0....
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the influence of chronic eicosanoid biosynthesis inhibition on life history of the greater waxmoth galleria mellonella and its ectoparasitoid bracon hebetor
Journal of Insect Physiology, 2011Co-Authors: Ender Büyükgüzel, Hasan Tunaz, David Stanley, Kemal BuyukguzelAbstract:Abstract Eicosanoids are oxygenated metabolites of three C20 polyunsaturated fatty acids, mainly arachidonic acid (AA; 20:4n-6), but also 20:3n-6 and 20:5n-3. Aside from their importance in biomedicine, Eicosanoids act in invertebrate biology. Prostaglandins (PGs) influence salt and water transport physiology in insect rectal epithelia and in Malpighian tubules. PGs also influence a few insect behaviors, including releasing oviposition behavior and behavioral fever. Eicosanoids act in ovarian development and in insect immunity. Because Eicosanoids act in several areas of insect biology, we posed the hypothesis that chronic inhibition of eicosanoid biosynthesis, in the absence of microbial challenge, can influence insect life table parameters, including developmental time, survival, adult longevity and parasitoid fecundity. Here we report that inhibiting eicosanoid biosynthesis throughout the larval life exerted minor influences on some life table parameters of the greater wax moth, Galleria mellonella and its ectoparasitoid, Bracon hebetor, however, the inhibitors strongly reduced the production and hatchability of the parasitoids’ eggs. The significance of the work relates to the potentials of understanding and targeting eicosanoid systems as a platform for developing new technologies of insect pest management. As seen here, the impact of targeting eicosanoid systems is seen in crucial moments of insect life histories, such as reproduction or immune challenge rather than in overall larval development.
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The influence of chronic eicosanoid biosynthesis inhibition on life history of the greater waxmoth, Galleria mellonella and its ectoparasitoid, Bracon hebetor
Journal of Insect Physiology, 2011Co-Authors: Ender Büyükgüzel, Hasan Tunaz, David Stanley, Kemal BuyukguzelAbstract:Eicosanoids are oxygenated metabolites of three C20 polyunsaturated fatty acids, mainly arachidonic acid (AA; 20:4n-6), but also 20:3n-6 and 20:5n-3. Aside from their importance in biomedicine, Eicosanoids act in invertebrate biology. Prostaglandins (PGs) influence salt and water transport physiology in insect rectal epithelia and in Malpighian tubules. PGs also influence a few insect behaviors, including releasing oviposition behavior and behavioral fever. Eicosanoids act in ovarian development and in insect immunity. Because Eicosanoids act in several areas of insect biology, we posed the hypothesis that chronic inhibition of eicosanoid biosynthesis, in the absence of microbial challenge, can influence insect life table parameters, including developmental time, survival, adult longevity and parasitoid fecundity. Here we report that inhibiting eicosanoid biosynthesis throughout the larval life exerted minor influences on some life table parameters of the greater wax moth, Galleria mellonella and its ectoparasitoid, Bracon hebetor, however, the inhibitors strongly reduced the production and hatchability of the parasitoids' eggs. The significance of the work relates to the potentials of understanding and targeting eicosanoid systems as a platform for developing new technologies of insect pest management. As seen here, the impact of targeting eicosanoid systems is seen in crucial moments of insect life histories, such as reproduction or immune challenge rather than in overall larval development. © 2011 Elsevier Ltd.
Edward A. Dennis - One of the best experts on this subject based on the ideXlab platform.
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Eicosanoid Storm in Infection and Inflammation
Nature Reviews Immunology, 2015Co-Authors: Edward A. Dennis, Paul C. NorrisAbstract:Eicosanoids are bioactive signalling lipids that regulate numerous homeostatic and inflammatory processes. Here, the authors review our current understanding of cellular eicosanoid metabolism and the physiological functions of pro-inflammatory and pro-resolving Eicosanoids in infection and inflammation.
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high throughput lipidomic analysis of fatty acid derived Eicosanoids and n acylethanolamines
Biochimica et Biophysica Acta, 2011Co-Authors: Darren S Dumlao, Matthew W Buczynski, Paul C. Norris, Richard Harkewicz, Edward A. DennisAbstract:Abstract Fatty acid-derived Eicosanoids and N-acylethanolamines (NAE) are important bioactive lipid mediators involved in numerous biological processes including cell signaling and disease progression. To facilitate research on these lipid mediators, we have developed a targeted high-throughput mass spectrometric based methodology to monitor and quantitate both Eicosanoids and NAEs, and can be analyzed separately or together in series. Each methodology utilizes scheduled multiple reaction monitoring (sMRM) pairs in conjunction with a 25 min reverse-phase HPLC separation. The eicosanoid methodology monitors 141 unique metabolites and quantitative amounts can be determined for over 100 of these metabolites against standards. The analysis covers Eicosanoids generated from cycloxygenase, lipoxygenase, cytochrome P450 enzymes, and those generated from non-enzymatic pathways. The NAE analysis monitors 36 metabolites and quantitative amounts can be determined for 33 of these metabolites against standards. The NAE method contains metabolites derived from saturated fatty acids, unsaturated fatty acids, and Eicosanoids. The lower limit of detection for Eicosanoids ranges from 0.1 pg to 1 pg, while NAEs ranges from 0.1 pg to 1000 pg. The rationale and design of the methodology is discussed. This article is part of a Special Issue entitled Lipodomics and Imaging Mass Spectrometry.
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tlr 4 and sustained calcium agonists synergistically produce Eicosanoids independent of protein synthesis in raw264 7 cells
Journal of Biological Chemistry, 2007Co-Authors: Matthew W Buczynski, Raymond A Deems, Rebecca C Bowersgentry, Daren Stephens, Andrej Grkovich, Edward A. DennisAbstract:Abstract Arachidonic acid is released by phospholipase A2 and converted into hundreds of distinct bioactive mediators by a variety of cyclooxygenases (COX), lipoxygenases (LO), and cytochrome P450s. Because of the size and diversity of the eicosanoid class of signaling molecules produced, a thorough and systematic investigation of these biological processes requires the simultaneous quantitation of a large number of Eicosanoids in a single analysis. We have developed a robust liquid chromatography/tandem mass spectrometry method that can identify and quantitate over 60 different Eicosanoids in a single analysis, and we applied it to agonist-stimulated RAW264.7 murine macrophages. Fifteen different Eicosanoids produced through COX and 5-LO were detected either intracellularly or in the media following stimulation with 16 different agonists of Toll-like receptors (TLR), G protein-coupled receptors, and purinergic receptors. No significant differences in the COX metabolite profiles were detected using the different agonists; however, we determined that only agonists creating a sustained Ca2+ influx were capable of activating the 5-LO pathway in these cells. Synergy between Ca2+ and TLR pathways was detected and discovered to be independent of NF-κB-induced protein synthesis. This demonstrates that TLR induction of protein synthesis and priming for enhanced phospholipase A2-mediated eicosanoid production work through two distinct pathways.
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detection and quantitation of Eicosanoids via high performance liquid chromatography electrospray ionization mass spectrometry
Methods in Enzymology, 2007Co-Authors: Raymond A Deems, Matthew W Buczynski, Rebecca C Bowersgentry, Richard Harkewicz, Edward A. DennisAbstract:Abstract Eicosanoids constitute a large class of biologically active arachidonic acid (AA) metabolites that play important roles in numerous physiological processes. Eicosanoids are produced by several distinct routes, including the cyclooxygenase, lipoxygenase, and P450 enzymatic pathways, as well as by nonenzymatic processes. In order to completely understand the eicosanoid response of a cell or tissue to a given stimulus, measuring the complete profile of Eicosanoids produced is important. Since the Eicosanoids are products of a single species, AA, and represent, for the most part, the addition of various oxygen species, the hundreds of Eicosanoids have very similar structures, chemistries, and physical properties. The identification and quantitation of all Eicosanoids in a single biological sample are a challenging task, one that high‐performance liquid chromatography‐mass spectrometry (LC‐MS) is well suited to handle. We have developed a LC‐MS/MS procedure for isolating, identifying, and quantitating a broad spectrum of Eicosanoids in a single biological sample. We currently can measure over 60 Eicosanoids in a 16‐min LC‐MS/MS analysis. Our method employs stable isotope dilution internal standards to quantitate these specific Eicosanoids. In the course of setting up the LC‐MS system, we have established a library that includes relative chromatographic retention times and tandem mass spectrometry data for the most common Eicosanoids. This library is available to the scientific community on the website www.lipidmaps.org .
Hasan Tunaz - One of the best experts on this subject based on the ideXlab platform.
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Inhibition of eicosanoid signaling leads to increased lipid peroxidation in a host/parasitoid system
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2016Co-Authors: Ender Büyükgüzel, Hasan Tunaz, Meltem Erdem, Ceyhun Küçük, Utku Can Atılgan, David Stanley, Kemal BuyukguzelAbstract:Abstract We posed the hypothesis that inhibition of eicosanoid biosynthesis leads to increased lipid peroxidation in insects. Here we report that rearing the greater wax moth, Galleria mellonella , on media supplemented with selected inhibitors of eicosanoid biosynthesis throughout the larval, pupal and adult life led to major alterations in selected oxidative and antioxidative parameters of wax moth and its ectoparasitoid, Bracon hebetor . The highest dietary dexamethasone (Dex), esculetin (Esc) and phenidone (Phe) led to increased malondialdehyde (MDA) levels and to elevated catalase (CAT) and glutathione-S-transferase (GST) activities in all developmental stages of host larvae. Dietary Phe resulted in increased MDA levels, and CAT activity in G. mellonella adults by about 4-fold and about 2-fold, respectively. The Phe effect on GST activity in all stages of the wax moth was expressed in a dose-dependent manner, increased to 140 nmol/mg protein/min in larvae. MDA levels were increased by over 30-fold in adult wasps reared on Dex- and Esc-treated hosts. CAT and GST activities were increased in adult parasitoids reared on Esc-and Phe-treated hosts. GST activity of Dex-treated parasitoid larvae increased from about 4 to over 30 nmol/mg protein/min. Dietary Phe led to increased GST activity, by about 25-fold, in adult wasps. These data indicate that chronic inhibition of eicosanoid biosynthesis leads to increased oxidative stress, strongly supporting our hypothesis. The significance of this work lies in understanding the roles of Eicosanoids in insect biology. Aside from other well-known Eicosanoids actions, we propose that Eicosanoids mediate reductions in oxidative stress.
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the influence of chronic eicosanoid biosynthesis inhibition on life history of the greater waxmoth galleria mellonella and its ectoparasitoid bracon hebetor
Journal of Insect Physiology, 2011Co-Authors: Ender Büyükgüzel, Hasan Tunaz, David Stanley, Kemal BuyukguzelAbstract:Abstract Eicosanoids are oxygenated metabolites of three C20 polyunsaturated fatty acids, mainly arachidonic acid (AA; 20:4n-6), but also 20:3n-6 and 20:5n-3. Aside from their importance in biomedicine, Eicosanoids act in invertebrate biology. Prostaglandins (PGs) influence salt and water transport physiology in insect rectal epithelia and in Malpighian tubules. PGs also influence a few insect behaviors, including releasing oviposition behavior and behavioral fever. Eicosanoids act in ovarian development and in insect immunity. Because Eicosanoids act in several areas of insect biology, we posed the hypothesis that chronic inhibition of eicosanoid biosynthesis, in the absence of microbial challenge, can influence insect life table parameters, including developmental time, survival, adult longevity and parasitoid fecundity. Here we report that inhibiting eicosanoid biosynthesis throughout the larval life exerted minor influences on some life table parameters of the greater wax moth, Galleria mellonella and its ectoparasitoid, Bracon hebetor, however, the inhibitors strongly reduced the production and hatchability of the parasitoids’ eggs. The significance of the work relates to the potentials of understanding and targeting eicosanoid systems as a platform for developing new technologies of insect pest management. As seen here, the impact of targeting eicosanoid systems is seen in crucial moments of insect life histories, such as reproduction or immune challenge rather than in overall larval development.
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The influence of chronic eicosanoid biosynthesis inhibition on life history of the greater waxmoth, Galleria mellonella and its ectoparasitoid, Bracon hebetor
Journal of Insect Physiology, 2011Co-Authors: Ender Büyükgüzel, Hasan Tunaz, David Stanley, Kemal BuyukguzelAbstract:Eicosanoids are oxygenated metabolites of three C20 polyunsaturated fatty acids, mainly arachidonic acid (AA; 20:4n-6), but also 20:3n-6 and 20:5n-3. Aside from their importance in biomedicine, Eicosanoids act in invertebrate biology. Prostaglandins (PGs) influence salt and water transport physiology in insect rectal epithelia and in Malpighian tubules. PGs also influence a few insect behaviors, including releasing oviposition behavior and behavioral fever. Eicosanoids act in ovarian development and in insect immunity. Because Eicosanoids act in several areas of insect biology, we posed the hypothesis that chronic inhibition of eicosanoid biosynthesis, in the absence of microbial challenge, can influence insect life table parameters, including developmental time, survival, adult longevity and parasitoid fecundity. Here we report that inhibiting eicosanoid biosynthesis throughout the larval life exerted minor influences on some life table parameters of the greater wax moth, Galleria mellonella and its ectoparasitoid, Bracon hebetor, however, the inhibitors strongly reduced the production and hatchability of the parasitoids' eggs. The significance of the work relates to the potentials of understanding and targeting eicosanoid systems as a platform for developing new technologies of insect pest management. As seen here, the impact of targeting eicosanoid systems is seen in crucial moments of insect life histories, such as reproduction or immune challenge rather than in overall larval development. © 2011 Elsevier Ltd.
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Eicosanoids act in nodulation reactions to bacterial infections in newly emerged adult honey bees, Apis mellifera, but not in older foragers
Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2001Co-Authors: Jon C Bedick, Hasan Tunaz, A.r. Nor Aliza, Marion D Ellis, Sean M Putnam, David StanleyAbstract:Nodulation is the first, and qualitatively predominant, cellular defense reaction to bacterial infections in insects. We tested the hypothesis that Eicosanoids also mediate nodulation reactions to bacterial challenge in adults of a social insect, the honey bee, Apis mellifera. Treating newly-emerged experimental bees with the eicosanoid biosynthesis inhibitor, dexamethasone, impaired nodulation reactions to bacterial infections, and the influence of dexamethasone was reversed by treating infected insects with arachidonic acid, an eicosanoid precursor. Several other eicosanoid biosynthesis inhibitors, including the cyclooxygenase inhibitor, indomethacin, and the dual cyclooxygenase/lipoxygenase inhibitor, phenidone, also impaired the ability of experimental honeybees to form nodules in reaction to bacterial challenge. The influence of phenidone on nodulation was expressed in a dose-dependent manner. However, in experiments with older honey bees foragers, similar bacterial challenge did not evoke nodulation reactions. We infer from our results that while Eicosanoids mediate cellular immune responses to bacterial infections in newly emerged honey bees, and more broadly, in most insect species, nodulation reactions to bacterial challenge probably do not occur in all phases of insect life cycles.
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Eicosanoids mediate nodulation reactions to bacterial infections in larvae of the butterfly, Colias eurytheme.
Comparative Biochemistry and Physiology Part C: Pharmacology Toxicology and Endocrinology, 1999Co-Authors: David Stanley, Hasan Tunaz, Rico L Rana, A.r. Nor Aliza, Jon C Bedick, William Wyatt Hoback, Jon S MillerAbstract:Abstract Nodulation is the first, and qualitatively predominant, cellular defense reaction to bacterial infections in insects. Treating larvae of the butterfly Colias eurytheme with the eicosanoid biosynthesis inhibitor dexamethasone, strongly impaired nodulation reactions to bacterial infections. The influence of dexamethasone was reversed by treating infected insects with arachidonic acid, an eicosanoid precursor. An eicosanoid biosynthesis system in C. eurytheme larvae is documented. Specifically, the presence of eicosanoid-precursor polyunsaturated fatty acids in tissue phospholipids was determined, an intracellular phospholipase A2 that can release arachidonic acid from tissue phospholipids was recorded, and eicosanoid biosynthesis, registered as conversion of exogenous radioactive 20:4n–6 into Eicosanoids, was observed. These findings support the hypothesis that Eicosanoids mediate cellular immune responses to bacterial infections in these butterfly larvae, and more broadly, in most, if not all, insects.