The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
David Stanley - One of the best experts on this subject based on the ideXlab platform.
-
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.
-
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.
-
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, David Stanley, Hasan Tunaz, Meltem Erdem, Ceyhun Küçük, Utku Can Atılgan, 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.
-
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, David Stanley, Hasan Tunaz, 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.
-
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, David Stanley, Hasan Tunaz, 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.
Youngjin Park - One of the best experts on this subject based on the ideXlab platform.
-
an entomopathogenic bacterium xenorhabdus hominickii anu101 produces oxindole and suppresses host insect immune response by inhibiting Eicosanoid Biosynthesis
Journal of Invertebrate Pathology, 2017Co-Authors: Md Sadekuzzaman, Youngjin Park, Jin Kyo JungAbstract:Abstract An entomopathogenic bacterium, Xenorhabdus hominickii ANU101, was isolated from an entomopathogenic nematode, Steinernema monticolum . X. hominickii exhibited significant insecticidal activities at ≥6.6 × 10 2 colony-forming units per larva against a lepidopteran insect, Spodoptera exigua with hemocoelic injection. The insecticidal activity of X. hominickii was reduced by an addition of arachidonic acid (AA, a catalytic product of PLA 2 ), but enhanced by an addition by dexamethasone (DEX, a specific inhibitor of PLA 2 ). S. exigua could defend the bacterial infection by forming hemocyte nodules. However, live X. hominickii significantly reduced the hemocytic nodulation compared to similar treatment with heat-killed X. hominickii . An addition of AA to live X . hominickii significantly rescued the immunosuppression. X. hominickii also inhibited phenoloxidase activity in hemolymph of S. exigua larvae. Furthermore, the bacteria suppressed gene expressions of antimicrobial peptides, such as attacin-1, attacin-2, defensin, gallerimycin and transferrin-1 of S. exigua . An organic extract of X. hominickii -cultured broth with ethyl acetate possessed oxindole and significantly suppressed hemocyte nodulation. Again, an addition of AA diminished the inhibitory activity of the organic extract against hemocyte nodulation. Oxindole alone inhibited hemocyte nodulation and PLA 2 enzyme activity. These results suggest that the entomopathogenicity of X. hominickii comes from its inhibitory activity against Eicosanoid Biosynthesis of target insects.
-
an entomopathogenic bacterium xenorhabdus nematophila suppresses expression of antimicrobial peptides controlled by toll and imd pathways by blocking Eicosanoid Biosynthesis
Archives of Insect Biochemistry and Physiology, 2013Co-Authors: Jihyun Hwang, Youngjin ParkAbstract:Immune-associated genes of the beet armyworm, Spodoptera exigua, were predicted from 454 pyrosequencing transcripts of hemocytes collected from fifth instar larvae challenged with bacteria. Out of 22,551 contigs and singletons, 36% of the transcripts had at least one significant hit (E-value cutoff of 1e-20) and used to predict immune-associated genes implicated in pattern recognition, prophenoloxidase activation, intracellular signaling, and antimicrobial peptides (AMPs). Immune signaling and AMP genes were further confirmed in their expression patterns in response to different types of microbial challenge. To discriminate the AMP expression signaling between Toll and Imd pathways, RNA interference was applied to specifically knockdown each signal pathway; the separate silencing treatments resulted in differential suppression of AMP genes. An entomopathogenic bacterium, Xenorhabdus nematophila, suppressed expression of most AMP genes controlled by Toll and Imd pathways, while challenge with heat-killed X. nematophila induced expression of all AMPs in experimental larvae. Benzylideneacetone (BZA), a metabolite of X. nematophila, suppressed the AMP gene inductions when it was co-injected with the heat-killed X. nematophila. However, arachidonic acid, a catalytic product of PLA2, significantly reversed the inhibitory effect of BZA on the AMP gene expression. This study suggests that X. nematophila suppresses AMP production controlled by Toll and Imd pathways by inhibiting Eicosanoid Biosynthesis in S. exigua.
-
the entomopathogenic bacterium xenorhabdus nematophila impairs hemocytic immunity by inhibition of Eicosanoid Biosynthesis in adult crickets gryllus firmus
Biological Control, 2006Co-Authors: David Stanley, Youngjin ParkAbstract:Abstract The bacterium, Xenorhabdus nematophila (Poinar and Thomas), is an obligate symbiont of nematodes in the genus Steinernema and a lethal insect pathogen. We investigated the hypothesis that one aspect of the bacterial virulence is the ability of X. nematophila to severely impair host insect cellular immune reactions to infection by inhibiting Eicosanoid Biosynthesis in the adult male cricket, Gryllus firmus (Scudder). Infection with heat-killed X. nematophila resulted in significant and time-dependent increases in hemocyte microaggregation reactions (from approximately 20/μl to nearly 100/μl hemolymph), nodulation reactions (from approximately 1 nodule/cricket to about 4 nodules/cricket) and hemocytic phospholipase A2 activity (from approximately 0.1 pmol hydrolyzed fatty acid/mg protein/h at 1 min post-injection to nearly 1.6 pmol hydrolyzed fatty acid/mg protein/h at 60 min post-injection). Infection with live bacteria did not stimulate increases in these three immune-related parameters—but did result in significant and time-dependent reduction in living hemocyte counts (from approximately 4400 hemocytes/μl hemolymph to approximately 3200/μl). Injecting the Eicosanoid-precursor fatty acid, arachidonic acid, into crickets infected with live bacteria reversed the bacterial effect on microaggregation and nodulation reactions, on living hemocyte populations and on hemocytic PLA2 activity. Our work indicates that X. nematophila is equipped with an arsenal of mechanisms to disable Eicosanoid-dependent host immune responses to the bacterium and possibly its host nematode. The efficacy of insect pathogens in biological control programs is limited, in part, by host immune functions. The significance of our work lies in understanding and possibly manipulating microbial mechanisms of disabling insect immunity.
-
The bacterium Xenorhabdus nematophila inhibits phospholipases A_2 from insect, prokaryote, and vertebrate sources
Naturwissenschaften, 2004Co-Authors: Youngjin Park, David StanleyAbstract:The bacterium, Xenorhabdus nematophila , is a virulent insect pathogen. Part of its pathogenicity is due to impairing cellular immunity by blocking Biosynthesis of Eicosanoids, the major recognized signal transduction system in insect cellular immunity. X. nematophila inhibits the first step in Eicosanoid Biosynthesis, phospholipase A_2 (PLA_2). Here we report that the bacterium inhibits PLA_2 from two insect immune tissues, hemocytes and fat body, as well as PLA_2s selected to represent a wide range of organisms, including prokaryotes, insects, reptiles, and mammals. Our finding on a bacterial inhibitor of PLA_2 activity contributes new insight into the chemical ecology of microbe–host interactions, which usually involve actions rather than inhibitors of PLA_2s.
-
An entomopathogenic bacterium, Xenorhabdus nematophila, inhibits hemocytic phospholipase A2 (PLA2) in tobacco hornworms Manduca sexta
Journal of Invertebrate Pathology, 2004Co-Authors: Youngjin Park, Hasan Tunaz, David StanleyAbstract:Abstract The entomopathogenic bacterium, Xenorhabdus nematophila , induces immunodepression in target insects and finally leads to lethal septicemia of the infected hosts. A hypothesis has been raised that the bacteria inhibit Eicosanoid-Biosynthesis pathway to interrupt immune signaling of the infected hosts. Here, we show direct evidence that X. nematophila inhibits the activity of phospholipase A2 (PLA2), the initial step in the Eicosanoid-Biosynthesis pathway. Inhibition of PLA2 was dependent on both incubation time with X. nematophila and the bacterial concentration in in vitro PLA2 preparations of Manduca sexta hemocytes. While living bacteria inhibited PLA2 activity, heat-killed X. nematophila rather increased PLA2 activity. X. nematophila secreted PLA2 inhibitor(s) which were detected in the organic, but not aqueous, extract of the bacterial culture medium. The PLA2 inhibitory activity of the organic extract was lost after heat treatment. These results clearly indicate that X. nematophila inhibits PLA2 activity, and thereby inhibits Eicosanoid Biosynthesis which leads to immunodepression of the infected hosts.
David W Stanleysamuelson - One of the best experts on this subject based on the ideXlab platform.
-
Eicosanoid Biosynthesis by hemocytes from the tobacco hornworm manduca sexta
Insect Biochemistry and Molecular Biology, 1995Co-Authors: Gadelhak G Gadelhak, Venkat K Pedibhotla, David W StanleysamuelsonAbstract:Abstract We describe Eicosanoid Biosynthesis by microsomal-enriched preparations of hemocytes from larvae of the tobacco hornworm Manduca sexta . Four major prostaglandins, PGA 2 , PGE 2 , PGD 2 and PGF 2α , and a lipoxygenase product that co-chromatographed with 15-hydroxyeicosatetraenoic acid (HETE) were synthesized under most conditions. The HETE's fraction was the predominant product. Eicosanoid Biosynthesis was sensitive to experimental conditions, including incubation time, temperature, and protein concentration. Optimal Biosynthesis was observed with 1.5 mg of microsomal-enriched protein, incubated at 30°C for 2 min. The hemocyte preparation is sensitive to low dosages of naproxin and esculetin. As in mammals, most lipoxygenase activity (87%) was localized in the cytosolic fraction of hemocytes. Unlike mammals, in which PGH synthase is associated with intracellular membranes, the hemocytic activity was detected in microsomal (59%), cytosolic (35%) and mitochondrial fractions (5%).
-
Eicosanoid Biosynthesis inhibitors modulate basal fluid secretion rates in the malpighian tubules of the ant formica polyctena
Journal of Insect Physiology, 1995Co-Authors: Emmy Van Kerkhove, Patrick Pirotte, David Petzel, David W StanleysamuelsonAbstract:Abstract Inhibition of Eicosanoid Biosynthesis in in vitro preparations of Malpighian tubules isolated from adult ants, Formica polyctena, reduced basal fluid secretion rates. Inhibition of total Eicosanoid Biosynthesis with 100 μM 5,8,11,14-eicosatetraynoic acid (ETYA) and inhibition of prostaglandin Biosynthesis with 100 μM indomethacin strongly reduced basal fluid secretion. The lipoxygenase inhibitor esculetin and the epoxygenase inhibitor SKF-525A did not influence fluid secretion rates during its application, although it blunted the cAMP effect somewhat after washout. These findings indicate that prostaglandins are involved in regulating fluid secretion rates in ant Malpighian tubules. Although stimulation by cAMP was somewhat reduced, the influence of ETYA and indomethacin on fluid secretion rates did not prevent adenosine 3′,5′-cyclic monophosphate from exerting its secretagogue effect. This indicates that the Eicosanoid Biosynthesis inhibitors acted in a physiological way on the Malpighian tubules. The Eicosanoid-precursor polyunsaturated fatty acid, arachidonic acid, is present in phospholipids of Malpighian tubules. This finding indicates that substrate for prostaglandin Biosynthesis is available.
-
inhibition of Eicosanoid Biosynthesis modulates basal fluid secretion in the malpighian tubules of the yellow fever mosquito aedes aegypti
Journal of Insect Physiology, 1992Co-Authors: David Petzel, David W StanleysamuelsonAbstract:Abstract Inhibition of Eicosanoid Biosynthesis in in vitro preparations of Malpighian tubules isolated from adult females of the yellow fever mosquito Aedes aegypti substantially reduced basal fluid secretion rates. The phospholipase A 2 inhibitor 5,8,11,14-eicosatetraynoic acid (ETYA) and the cyclooxygenase inhibitor indomethacin far more effectively reduced basal fluid secretion than the epoxygenase inhibitor SKF-525A. The lipoxygenase inhibitor esculetin had no effect on basal fluid secretion. These findings indicate that products of cyclooxygenase are involved in regulating basal fluid secretion in Malpighian tubules. The effects of indomethacin were expressed in a dose-dependent manner, further indicating that Eicosanoids are physiologically involved in fluid secretion. The effects of cyclooxygenase inhibition on reduction of basal secretion rates have not prevented adenosine 3′,5′-cyclic monophosphate (cAMP) from exerting its secretagogue effect. These results strongly support the hypothesis that Eicosanoids, especially prostaglandins, are involved in Malpighian tubule function in A. aegypti . Recognition that Eicosanoids may be involved in regulating basal fluid secretion rates introduces a previously unrecognized tier of regulatory physiology into insect renal function.
Kemal Buyukguzel - One of the best experts on this subject based on the ideXlab platform.
-
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, David Stanley, Hasan Tunaz, Meltem Erdem, Ceyhun Küçük, Utku Can Atılgan, 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.
-
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, David Stanley, Hasan Tunaz, 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.
-
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, David Stanley, Hasan Tunaz, 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.
-
effect of Eicosanoid Biosynthesis inhibitors on the haemolymph protein profile of galleria mellonella linnaeus 1758 larvae lepidoptera pyralidae
2011Co-Authors: Kemal BuyukguzelAbstract:2Summary Eicosanoids mediate insects cellular and humoral immune reactions and stress responses. Function of these mediators can be specifically blocked using different Eicosanoid Biosynthesis inhibitors (EBIs). Effects of EBIs on total haemolymph protein composition have not been extensively studied in insects. We posed the hypothesis that Eicosanoids also mediate physiological homeostasis by regulating protein profiles involved in stress response and other defensive reactions. To test this idea, we reared greater wax moth Galleria mellonella (Linnaeus,1758) (Lepidoptera: Pyralidae) larvae on artificial diets containing 0.001, 0.01, 0.1 or 1.0% of specific EBIs with different mode of action: Esculetin, dexamethasone and phenidone. Feeding larvae with esculetin caused significantly dose-dependent changes in 45 kDa protein fraction (one of 16 proteins detected) using sodium dodecyl-sulphate polyacrylamide gradient gel electrophoresis followed by silver staining. Other main haemolymph proteins, lipophorins (ApoLP-I) and storage proteins, were not affected by EBIs treatments. Dexamethasone and phenidone caused no significant differences in detected protein fractions. We infer from these findings that Eicosanoids, at least lipoxygenase products, have been implicated in the protein composition of insect tissues as structural and functional concept. Although it has not yet been possible to use directly EBIs for insect pest control, our results bring new data to understand physiological signaling systems in insects.
-
the effects of Eicosanoid Biosynthesis inhibitors on oxidativestress antioxidant response and protein profiles in hemolymphof galleria mellonella larvae
2008Co-Authors: Ender Büyükgüzel, Pavel Hyrsl, Kemal BuyukguzelAbstract:Effects of Eicosanoid Biosynthesis inhibitors (EBIs) esculetin, dexamethasone and phenidone on hemolymph concentrations of the oxidative stress indicator malondialdehyde (MDA), antioxidant enzyme (glutathione S-transferase GST) and protein profiles of greater wax moth, Galleria mellonella (L.) seventh instar larvae were investigated. The insects were reared from first instars on artificial diets containing 0.001, 0.01, 0.1 and 1.0 g EBIs per 100 g of diets. MDA content was significantly increased in the presence of esculetin. Low concentrations of esculetin led to increased GST activity. Dexamethasone at concentrations of 0.001 and 0.01% significantly resulted in increased hemolymph MDA content. However, high dietary dexamethasone concentrations caused significant decrease in MDA content while these concentrations resulted in increased GST activity by about three-fold. Dietary phenidone led to increased MDA content and GST activity in the larvae. The quantity of the 45 kDa protein fraction from total 16 protein detected was increased with increasing esculetin concentrations. An increase after phenidone and dexamethasone exposure was detected only at 0.001 and 0.01% concentration. Other main hemolymph proteins such as ApoLP-I and storage proteins were not altered in larvae reared on diets amended with the EBIs. We suggest that 45 kDa protein may be an oxidative stress-related protein in hemolymph of G. mellonella. This is the first demonstration that antioxidative responses to a EBI exposure are modulated by a physiological system that includes Eicosanoid Biosynthesis.
Anthony S Clare - One of the best experts on this subject based on the ideXlab platform.
-
sea nine 211 4 5 dichloro 2 n octyl 3 2h isothiazolone is a potent stimulator of Eicosanoid Biosynthesis in the sea squirt ciona intestinalis l
Biofouling, 1999Co-Authors: John Knight, Andrew F Rowley, Anthony S ClareAbstract:The isothiazolone, Sea‐Nine 211™, is a broad‐spectrum antifoulant whose mechanism of action is poorly understood. In the light of recent reports that eicosa‐noids may modulate invertebrate larval settlement, the present study examined the effect of Sea‐Nine 211 on Eicosanoid Biosynthesis in the sea squirt, Ciona intestinalis. Using RP‐HPLC and examination of peak absorption spectra, the tunic of this species was shown to produce a range of lipoxygenase products, including 8‐HEPE, 12‐HEPE, 8,15‐diHEPE and 8,15‐diHETE. Sea‐Nine 211™ was similar in potency to the calcium ionophore, A 23187, in inducing Biosynthesis of these Eicosanoids, being maximally effective at 5–10 μM. While the effect of Sea‐Nine 211 on C. intestinalis settlement has yet to be examined, it is suggested that this antifoulant may exert its action, at least in part, by modulating Eicosanoid Biosynthesis.
-
Sea‐Nine™ 211 (4,5‐dichloro‐2‐(n‐octyl)‐3(2H)‐isothiazolone) is a Potent Stimulator of Eicosanoid Biosynthesis in the Sea Squirt, Ciona intestinalis (L.)
Biofouling, 1999Co-Authors: John Knight, Andrew F Rowley, Anthony S ClareAbstract:The isothiazolone, Sea‐Nine 211™, is a broad‐spectrum antifoulant whose mechanism of action is poorly understood. In the light of recent reports that eicosa‐noids may modulate invertebrate larval settlement, the present study examined the effect of Sea‐Nine 211 on Eicosanoid Biosynthesis in the sea squirt, Ciona intestinalis. Using RP‐HPLC and examination of peak absorption spectra, the tunic of this species was shown to produce a range of lipoxygenase products, including 8‐HEPE, 12‐HEPE, 8,15‐diHEPE and 8,15‐diHETE. Sea‐Nine 211™ was similar in potency to the calcium ionophore, A 23187, in inducing Biosynthesis of these Eicosanoids, being maximally effective at 5–10 μM. While the effect of Sea‐Nine 211 on C. intestinalis settlement has yet to be examined, it is suggested that this antifoulant may exert its action, at least in part, by modulating Eicosanoid Biosynthesis.