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Haraji S, Talaei-Hassanloui R, Ahmed S, Jin G, Lee D, Kim Y. Apolipoprotein D3 and LOX product play a role in immune-priming of a lepidopteran insect, Spodoptera exigua. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2024; 158:105198. [PMID: 38795942 DOI: 10.1016/j.dci.2024.105198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 05/22/2024] [Accepted: 05/23/2024] [Indexed: 05/28/2024]
Abstract
Immune-priming occurs in insects after a prior pathogen exposure. However, its underlying mechanism in insects remains elusive. In the present work, immune-priming was detected in a lepidopteran insect, Spodoptera exigua. Specifically, a prior infection with a heat-killed pathogenic bacterium, Escherichia coli, led to increased survival upon the second infection of different pathogens. Plasma collected from larvae with the prior infection possessed the immune-priming factor(s) that significantly up-regulated cellular and humoral immune responses of naïve larvae. Our study also finds that variations in the timing of plasma collection for priming larvae resulted in distinct impacts on both cellular and humoral responses. However, when the active plasma exhibiting the immune-priming was heat-treated, it lost this priming activity, therefore suggesting that protein factor(s) play a role in this immune-priming. An immunofluorescence assay showed that the hemocytes collected from the immune-primed larvae highly reacted to a polyclonal antibody specific to a vertebrate lipocalin, apolipoprotein D (ApoD). Among 27 ApoD genes (Se-ApoD1 ∼ Se-ApoD27) of S. exigua, Se-ApoD3 was found to be highly induced during the immune-priming, in which it was shown to be expressed in hemocytes and fat body from a fluorescence in situ hybridization analysis. RNA interference of Se-ApoD3 expression significantly impaired the immune-priming of S. exigua larvae. Moreover, the inhibition of eicosanoid biosynthesis suppressed the immune-priming, in which treatment with a lipoxygenase (LOX) inhibitor-and not treatment with a cyclooxygenase inhibitor-suppressed immune-priming. Further, an addition of LOX product such as lipoxin A4 or lipoxin B4 significantly rescued the lost immune-priming activity. Taken together, these results suggest that a complex of ApoD3 and LOX product mediates the immune-priming activity of S. exigua.
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Affiliation(s)
- Shiva Haraji
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea; Department of Plant Protection, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran
| | - Reza Talaei-Hassanloui
- Department of Plant Protection, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
| | - Shabbir Ahmed
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea
| | - Gahyeon Jin
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea
| | - Donghee Lee
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea.
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Shao L, Wang W, Gong X, Yu Y, Xue J, Zeng X, Liu J. The Toxicity Differences of Fluralaner against the Red Imported Fire Ant ( Solenopsis invicta) at Different Developmental Stages. Int J Mol Sci 2023; 24:15627. [PMID: 37958611 PMCID: PMC10649654 DOI: 10.3390/ijms242115627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 10/18/2023] [Accepted: 10/24/2023] [Indexed: 11/15/2023] Open
Abstract
The red imported fire ant (RIFA), Solenopsis invicta, is an invasive pest that causes damage to agricultural and ecological environments worldwide. Fluralaner is a new isoxazoline pesticide with the potential to become a control agent against RIFA. However, it is not clear whether S. invicta responds the same way to fluralaner at different reproductive stages. The present study firstly evaluated the toxicity of fluralaner to S. invicta at different developmental stages, finding that fourth instar larvae (LD50, 1744.23 mg/kg) and worker ants (LD50, 8.62 mg/kg) were differently susceptible to fluralaner, while the mortality rate of fourth instar larvae was significantly lower at the same concentration of 10 mg/L (5.56 ± 3.14%) than that of worker ants (62.22 ± 3.14%), demonstrating a greater tolerance to fluralaner. Subsequently, the metabolic responses of worker and larval ants to fluralaner stress (10 mg/L) were investigated using non-targeted metabolomics, which indicated that the amount of differential metabolites and the KEGG metabolic pathways enriched were different between workers and larvae when exposed to the same dose (10 mg/L) of fluralaner. Differential metabolites of larvae and worker ants under fluralaner stress were mainly concentrated in organic acids and their derivatives, lipids and lipid-like molecules, nucleosides, nucleotides, and analogues, combined with the enriched metabolic pathways, revealed that the differential metabolic responses of larvae and worker ants were mainly in energy metabolism, detoxification metabolism, and neurotransmitter ligands. Workers consumed more substrates in the arginine synthesis pathway (l-glutamic acid, l-aspartic acid, and fumaric acid) to provide energy for the detoxification (glutathione) of pesticides when exposed to fluralaner stress, and the high accumulation of l-aspartic acid induced excitotoxicity in the worker ants. Larval ants consumed more arachidonic acid to synthesize PG D2, and changes in the metabolism of antioxidants such as catechins, hesperidin, and l-ascorbic acid suggested that larvae were more capable of scavenging the ROS response than worker ants. The results of non-targeted metabolomics successfully revealed differences in the sensitivity of larvae and workers to fluralaner agents, providing insights into the fluralaner control of Solenopsis invicta.
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Affiliation(s)
| | | | | | | | | | | | - Jiali Liu
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (L.S.); (W.W.); (X.G.); (Y.Y.); (J.X.); (X.Z.)
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Hrithik MTH, Kim Y. Immune responses of the Asian onion moth, Acrolepiopsis sapporensis, and their genetic factors from RNA-Seq analysis. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2023; 114:1-21. [PMID: 37459157 DOI: 10.1002/arch.22038] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/05/2023] [Accepted: 07/07/2023] [Indexed: 09/27/2023]
Abstract
A nonmodel insect, Acrolepiopsis sapporensis, has been analyzed in immune responses. The total hemocytes in the fifth instar larvae were 2.33 × 106 cells/mL. These hemocytes comprised at least five different types and different relative ratios: 47% granulocytes, 26% plasmatocytes, 11% oenocytoid, 8% prohemocytes, and 5% spherulocytes. Upon bacterial challenge, some of the hemocytes exhibited typical hemocyte-spreading behaviors, such as focal adhesion, and filopodial and lamellipodial cytoplasmic extensions. The hemocyte behaviors induced cellular immune responses demonstrated by nodule formation. In addition, the plasma collected from the immune-challenged larvae exhibited humoral immune responses by bacterial growth inhibition along with enhanced phenoloxidase enzyme activity. These cellular and humoral immune responses were further analyzed by determining the immune-associated genes from a transcriptome generated by RNA-Seq. A total of about 12 Gb sequences led to about 218,116 contigs, which were predicted to encode about 46,808 genes. Comparative expression analysis showed 8392 uniquely expressed genes in the immune-challenged larvae. Differentially expressed gene (DEG) analysis among the commonly expressed genes indicated that 782 genes were upregulated and 548 genes were downregulated in the expressions after bacterial challenge. These immune-associated genes included pattern recognition receptors, immune mediation/signaling genes, and various immune effectors. Specifically, the genetic components of the Toll, IMD, and JAK/STAT immune signaling pathways were included in the DEG database. These results demonstrate the immune responses of A. sapporensis larvae and suggest the genes associated with the immune responses in this nonmodel insect.
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Affiliation(s)
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, Korea
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Elliott K, Caicedo PA, Haunerland NH, Lowenberger C. Profiling lipidomic changes in dengue-resistant and dengue-susceptible strains of Colombian Aedes aegypti after dengue virus challenge. PLoS Negl Trop Dis 2023; 17:e0011676. [PMID: 37847671 PMCID: PMC10581493 DOI: 10.1371/journal.pntd.0011676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 09/20/2023] [Indexed: 10/19/2023] Open
Abstract
The mosquito Aedes aegypti is the primary vector for all four serotypes of dengue viruses (DENV1-4), which infect millions across the globe each year. Traditional insecticide programs have been transiently effective at minimizing cases; however, insecticide resistance and habitat expansion have caused cases of DENV to surge over the last decade. There is an urgent need to develop novel vector control measures, but these are contingent on a detailed understanding of host-parasite interactions. Here, we have utilized lipidomics to survey the profiles of naturally DENV-resistant (Cali-MIB) or susceptible (Cali-S) populations of Ae. aegypti, isolated from Cali, Colombia, when fed on blood meals containing DENV. Control insects were fed on a DENV-free blood meal. Midguts were dissected from Cali-MIB and Cali-S females at three time points post-infectious blood meal, 18, 24 and 36h, to identify changes in the lipidome at key times associated with the entry, replication and exit of DENV from midgut cells. We used principal component analysis to visualize broad patterns in lipidomic profiles between the treatment groups, and significance analysis of microarray to determine lipids that were altered in response to viral challenge. These data can be used to identify molecules or metabolic pathways particular to the susceptible or refractory phenotypes, and possibly lead to the generation of stable, DENV-resistant strains of Ae. aegypti.
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Affiliation(s)
- Keenan Elliott
- Simon Fraser University, Department of Biological Sciences, C2D2 Research Group, Burnaby, British Columbia, Canada
| | - Paola A. Caicedo
- Universidad Icesi, Natural Science Faculty, Department of Biology, Cali, Colombia
| | - Norbert H. Haunerland
- Simon Fraser University, Department of Biological Sciences, C2D2 Research Group, Burnaby, British Columbia, Canada
| | - Carl Lowenberger
- Simon Fraser University, Department of Biological Sciences, C2D2 Research Group, Burnaby, British Columbia, Canada
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Choi DY, Kim Y. Prostaglandin E 2 mediates chorion formation of the Asian tiger mosquito, Aedes albopictus, at late oogenesis. INSECT MOLECULAR BIOLOGY 2023; 32:484-509. [PMID: 37158315 DOI: 10.1111/imb.12846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 04/25/2023] [Indexed: 05/10/2023]
Abstract
Chorion-i.e., the eggshell-is formed during the late stage of oogenesis by follicular epithelium in the ovary. Although the endocrine signal(s) driving choriogenesis remain unclear in mosquitoes, this process in other insects has been suspected to involve the mediation of prostaglandins (PGs). This study tested the role of PG in the choriogenesis of the Asian tiger mosquito, Aedes albopictus, and its influence on controlling the expressions of genes associated with chorion formation by a transcriptome analysis. An immunofluorescence assay showed that PGE2 is localised in follicular epithelium. With the treatment of aspirin, an inhibitor of PG biosynthesis, at mid oogenesis, the PGE2 signal disappeared in the follicular epithelium led to significantly inhibited chorion formation along with a malformed eggshell. Ovary transcriptomes were assessed by RNASeq at the mid and late ovarian developmental stages. Differentially expressed genes (DEGs) exhibiting more than twofold changes in expression levels included 297 genes at mid stage and 500 genes at late stage. These DEGs at these two developmental stages commonly included genes associated with egg and chorion proteins of Ae. albopictus. Most chorion-associated genes were clustered in the 168 Mb region on a chromosome and exhibited significantly induced expressions at both ovarian developmental stages. The inhibition of PG biosynthesis significantly suppressed the expression of the chorion-associated genes while the addition of PGE2 rescued the gene expressions and led to recovery of choriogenesis. These results suggest that PGE2 mediates the choriogenesis of Ae. albopictus.
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Affiliation(s)
- Du-Yeol Choi
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, South Korea
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, South Korea
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Terrill Sondag EE, Stewart Merrill TE, Drnevich J, Holmes JR, Fischer EK, Cáceres CE, Strickland LR. Differential gene expression in response to fungal pathogen exposure in the aquatic invertebrate, Daphnia dentifera. Ecol Evol 2023; 13:e10354. [PMID: 37529587 PMCID: PMC10375369 DOI: 10.1002/ece3.10354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 06/05/2023] [Accepted: 07/12/2023] [Indexed: 08/03/2023] Open
Abstract
While vertebrate immune systems are appreciated for their complexity and adaptability, invertebrate immunity is often considered to be less complex. However, immune responses in many invertebrates likely involve sophisticated processes. Interactions between the crustacean host Daphnia dentifera and its fungal pathogen Metschnikowia bicuspidata provide an excellent model for exploring the mechanisms underlying crustacean immunity. To explore the genomic basis of immunity in Daphnia, we used RNA-sequencing technology to quantify differential gene expression between individuals of a single host genotype exposed or unexposed to M. bicuspidata over 24 h. Transcriptomic analyses showed that the number of differentially expressed genes between the control (unexposed) and experimental (exposed) groups increased over time. Gene ontology enrichment analysis revealed that differentially expressed genes were enriched for immune-related molecules and processes, such as cuticle development, prostaglandin, and defense response processes. Our findings provide a suite of immunologically relevant genes and suggest the presence of a rapidly upregulated immune response involving the cuticle in Daphnia. Studies involving gene expression responses to pathogen exposure shine a light on the processes occurring during the course of infection. By leveraging knowledge on the genetic basis for immunity, immune mechanisms can be more thoroughly understood to refine our understanding of disease spread within invertebrate populations.
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Affiliation(s)
- Emily E. Terrill Sondag
- Department of Evolution, Ecology, and Behavior, School of Integrative BiologyUniversity of Illinois Urbana‐ChampaignUrbanaIllinoisUSA
| | - Tara E. Stewart Merrill
- Department of Evolution, Ecology, and Behavior, School of Integrative BiologyUniversity of Illinois Urbana‐ChampaignUrbanaIllinoisUSA
- Coastal and Marine LaboratoryFlorida State UniversitySt. TeresaFloridaUSA
| | - Jenny Drnevich
- High Performance Computing in BiologyUniversity of Illinois Urbana‐ChampaignUrbanaIllinoisUSA
| | - Jessica R. Holmes
- High Performance Computing in BiologyUniversity of Illinois Urbana‐ChampaignUrbanaIllinoisUSA
| | - Eva K. Fischer
- Department of Evolution, Ecology, and Behavior, School of Integrative BiologyUniversity of Illinois Urbana‐ChampaignUrbanaIllinoisUSA
| | - Carla E. Cáceres
- Department of Evolution, Ecology, and Behavior, School of Integrative BiologyUniversity of Illinois Urbana‐ChampaignUrbanaIllinoisUSA
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Hrithik MTH, Hong J, Kim Y. Identification of four secretory phospholipase A 2s in a lepidopteran insect, Acrolepiopsis sapporensis, and their functional association with cellular immune responses. Front Endocrinol (Lausanne) 2023; 14:1190834. [PMID: 37424852 PMCID: PMC10328117 DOI: 10.3389/fendo.2023.1190834] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 06/07/2023] [Indexed: 07/11/2023] Open
Abstract
Background Eicosanoids are a group of the oxygenated C20 polyunsaturated fatty acids and play crucial roles in mediating various insect physiological processes. Catalytic activity of phospholipase A2 (PLA2) provides an initial substrate, arachidonic acid (AA), for subsequent eicosanoid biosynthesis. Results This study identified four different secretory PLA2 (As-PLA2A-As-PLA2D) genes encoded in the Asian onion moth, Acrolepiopsis sapporensis. A phylogenetic analysis indicated that As-PLA2A and As-PLA2D are clustered with Group III PLA2s while As-PLA2B and As-PLA2C are clustered with Group XII and Group X PLA2s, respectively. Expression levels of these PLA2 genes increased along with larval development, especially in the fat body. A bacterial immune challenge upregulated the basal expression levels of the four PLA2 genes, which resulted in significant increases of the PLA2 enzyme activity. The enzyme activity was susceptible to a calcium chelator or reducing agent, suggesting Ca2+ dependency and disulfide linkage required for the catalytic activities of the secretory type of PLA2s. In addition, the PLA2 activity was also susceptible to bromophenacyl bromide (BPB), a specific inhibitor to sPLA2, but not to intracellular PLA2 inhibitors. An addition of BPB to the immune challenge significantly prevented hemocyte-spreading behavior of A. sapporensis. BPB treatment also suppressed a cellular immune response measured by hemocyte nodule formation. However, the immunosuppression was significantly rescued by the AA addition. To determine the PLA2(s) responsible for the immunity, individual RNA interference (RNAi) treatments specific to each of the four PLA2s were performed. Injection of gene-specific double-stranded RNAs caused significant reductions in the transcript level in all four PLA2s. In all four PLA2s, the RNAi treatments prevented the cellular immune response even after the immune challenge. Conclusion This study reports four secretory PLA2s encoded in A. sapporensis and their function in mediating cellular immunity.
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Parks SC, Okakpu OK, Azizpor P, Nguyen S, Martinez-Beltran S, Claudio I, Anesko K, Bhatia A, Dhillon HS, Dillman AR. Parasitic nematode secreted phospholipase A 2 suppresses cellular and humoral immunity by targeting hemocytes in Drosophila melanogaster. Front Immunol 2023; 14:1122451. [PMID: 37006283 PMCID: PMC10050561 DOI: 10.3389/fimmu.2023.1122451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 02/15/2023] [Indexed: 03/17/2023] Open
Abstract
A key aspect of parasitic nematode infection is the nematodes' ability to evade and/or suppress host immunity. This immunomodulatory ability is likely driven by the release of hundreds of excretory/secretory proteins (ESPs) during infection. While ESPs have been shown to display immunosuppressive effects on various hosts, our understanding of the molecular interactions between individual proteins released and host immunity requires further study. We have recently identified a secreted phospholipase A2 (sPLA2) released from the entomopathogenic nematode (EPN) Steinernema carpocapsae we have named Sc-sPLA2. We report that Sc-sPLA2 increased mortality of Drosophila melanogaster infected with Streptococcus pneumoniae and promoted increased bacterial growth. Furthermore, our data showed that Sc-sPLA2 was able to downregulate both Toll and Imd pathway-associated antimicrobial peptides (AMPs) including drosomycin and defensin, in addition to suppressing phagocytosis in the hemolymph. Sc-sPLA2 was also found to be toxic to D. melanogaster with the severity being both dose- and time-dependent. Collectively, our data highlighted that Sc-sPLA2 possessed both toxic and immunosuppressive capabilities.
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Affiliation(s)
- Sophia C. Parks
- Department of Nematology, University of California, Riverside, CA, United States
| | - Ogadinma K. Okakpu
- Department of Nematology, University of California, Riverside, CA, United States
| | - Pakeeza Azizpor
- Department of Nematology, University of California, Riverside, CA, United States
| | - Susan Nguyen
- Department of Nematology, University of California, Riverside, CA, United States
| | | | - Isaiah Claudio
- Department of Nematology, University of California, Riverside, CA, United States
| | - Kyle Anesko
- Department of Nematology, University of California, Riverside, CA, United States
| | - Anil Bhatia
- Metabolomics Core Facility, IIGB, University of California, Riverside, CA, United States
| | - Harpal S. Dhillon
- Department of Nematology, University of California, Riverside, CA, United States
| | - Adler R. Dillman
- Department of Nematology, University of California, Riverside, CA, United States
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Choi DY, Kim Y. PGE 2 mediation of egg development in Western flower thrip, Frankliniella occidentalis. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2023; 112:e21949. [PMID: 35749583 DOI: 10.1002/arch.21949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/07/2022] [Accepted: 06/08/2022] [Indexed: 06/15/2023]
Abstract
Eicosanoids mediate various insect physiological processes, including reproduction. Especially, the eicosanoid prostaglandin E2 (PGE2 ) is known to mediate oocyte development in some insects. The explosive reproductive potential of the Western flower thrips, Frankliniella occidentalis, damages various agricultural crops. However, little is known about the underlying physiological processes of egg development in this pest. This study found that treatment with aspirin (ASP) (a specific cyclooxygenase (COX) inhibitor) used to inhibit PGE2 biosynthesis during ovarian development significantly suppressed the reproduction of female F. occidentalis. However, the addition of PGE2 to ASP-treated females significantly rescued the suppressed reproduction. PGE2 was detected in growing ovarian follicles in an immunofluorescence assay. The hypothetical biosynthetic machinery of PGE2 was predicted from the F. occidentalis genome and included phospholipase A2 (PLA2 ), COX-like peroxidase (POX), and PGE2 synthase (PGES). Three specific PLA2 s were highly expressed in female adults during active oogenesis. Specific POX and PGES genes also showed high expression during active oogenesis. The adverse effect of ASP treatment on oogenesis was observed in follicle formation in the germarium where the follicle numbers in an ovariole were decreased, which resulted in hypotrophied ovaries. This impairment was rescued by the addition of PGE2 . ASP treatment also significantly inhibited chorion formation and suppressed gene expression associated with choriogenesis, which included chorion protein, mucin, and yellow while it did not inhibit vitellogenin gene expression. However, the addition of PGE2 induced the expression of the target genes suppressed by ASP treatment and rescued chorion formation. These results suggest that PGE2 mediated ovarian development by affecting follicle formation and choriogenesis in F. occidentalis.
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Affiliation(s)
- Du-Yeol Choi
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Korea
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Korea
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Aspirin Inhibition of Prostaglandin Synthesis Impairs Mosquito Egg Development. Cells 2022; 11:cells11244092. [PMID: 36552860 PMCID: PMC9776805 DOI: 10.3390/cells11244092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 12/08/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022] Open
Abstract
Several endocrine signals mediate mosquito egg development, including 20-hydroxyecdysone (20E). This study reports on prostaglandin E2 (PGE2) as an additional, but core, mediator of oogenesis in a human disease-vectoring mosquito, Aedes albopictus. Injection of aspirin (an inhibitor of cyclooxygenase (COX)) after blood-feeding (BF) inhibited oogenesis by preventing nurse cell dumping into a growing oocyte. The inhibitory effect was rescued by PGE2 addition. PGE2 was found to be rich in nurse cells and follicular epithelium after BF. RNA interference (RNAi) treatments of PG biosynthetic genes, including PLA2 and two COX-like peroxidases, prevented egg development. Interestingly, 20E treatment significantly increased the expressions of PG biosynthetic genes, while the RNAi of Shade (which is a 20E biosynthetic gene) expression prevented inducible expressions after BF. Furthermore, RNAi treatments of PGE2 receptor genes suppressed egg production, even under PGE2. These results suggest that a signaling pathway of BF-20E-PGE2 is required for early vitellogenesis in the mosquito.
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Cui C, Tang X, Xing J, Sheng X, Chi H, Zhan W. Single-cell RNA-seq uncovered hemocyte functional subtypes and their differentiational characteristics and connectivity with morphological subpopulations in Litopenaeus vannamei. Front Immunol 2022; 13:980021. [PMID: 36177045 PMCID: PMC9513592 DOI: 10.3389/fimmu.2022.980021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 08/22/2022] [Indexed: 12/01/2022] Open
Abstract
Hemocytes play central roles in shrimp immune system, whereas whose subclasses have not yet been completely defined. At present, the morphological classification of hemocytes is inadequate to classify the complete hemocyte repertoire and elucidate the functions and differentiation and maturation processes. Based on single-cell RNA sequencing (scRNA-seq) of hemocytes in healthy Litopenaeus vannamei, combined with RNA-FISH and flow cytometric sorting, we identified three hemocyte clusters including TGase+ cells, CTL+ cells and Crustin+ cells, and further determined their functional properties, potential differentiation trajectory and correspondence with morphological subpopulations. The TGase+ cells were mainly responsible for the coagulation, exhibiting distinguishable characteristics of hyalinocyte, and appeared to be developmentally arrested at an early stage of hemocyte differentiation. The CTL+ cells and Crustin+ cells arrested at terminal stages of differentiation mainly participated in recognizing foreign pathogens and initiating immune defense responses, owning distinctive features of granule-containing hemocytes. Furthermore, we have revealed the functional sub-clusters of three hemocyte clusters and their potential differentiation pathways according to the expression of genes involved in cell cycle, cell differentiation and immune response, and the successive differentiation and maturation of hyalinocytes to granule-containing hemocytes have also mapped. The results revealed the diversity of shrimp hemocytes and provide new theoretical rationale for hemocyte classification, which also facilitate systematic research on crustacean immunity.
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Affiliation(s)
- Chuang Cui
- Laboratory of Pathology and Immunology of Aquatic Animals, The Key Laboratory of Mariculture, Ministry of Education (KLMME), Ocean University of China, Qingdao, China
| | - Xiaoqian Tang
- Laboratory of Pathology and Immunology of Aquatic Animals, The Key Laboratory of Mariculture, Ministry of Education (KLMME), Ocean University of China, Qingdao, China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Jing Xing
- Laboratory of Pathology and Immunology of Aquatic Animals, The Key Laboratory of Mariculture, Ministry of Education (KLMME), Ocean University of China, Qingdao, China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Xiuzhen Sheng
- Laboratory of Pathology and Immunology of Aquatic Animals, The Key Laboratory of Mariculture, Ministry of Education (KLMME), Ocean University of China, Qingdao, China
| | - Heng Chi
- Laboratory of Pathology and Immunology of Aquatic Animals, The Key Laboratory of Mariculture, Ministry of Education (KLMME), Ocean University of China, Qingdao, China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Wenbin Zhan
- Laboratory of Pathology and Immunology of Aquatic Animals, The Key Laboratory of Mariculture, Ministry of Education (KLMME), Ocean University of China, Qingdao, China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
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Roy MC, Nam K, Kim J, Stanley D, Kim Y. Thromboxane Mobilizes Insect Blood Cells to Infection Foci. Front Immunol 2022; 12:791319. [PMID: 34987515 PMCID: PMC8720849 DOI: 10.3389/fimmu.2021.791319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 11/18/2021] [Indexed: 01/18/2023] Open
Abstract
Innate immune responses are effective for insect survival to defend against entomopathogens including a fungal pathogen, Metarhizium rileyi, that infects a lepidopteran Spodoptera exigua. In particular, the fungal virulence was attenuated by cellular immune responses, in which the conidia were phagocytosed by hemocytes (insect blood cells) and hyphal growth was inhibited by hemocyte encapsulation. However, the chemokine signal to drive hemocytes to the infection foci was little understood. The hemocyte behaviors appeared to be guided by a Ca2+ signal stimulating cell aggregation to the infection foci. The induction of the Ca2+ signal was significantly inhibited by the cyclooxygenase (COX) inhibitor. Under the inhibitory condition, the addition of thromboxane A2 or B2 (TXA2 or TXB2) among COX products was the most effective to recover the Ca2+ signal and hemocyte aggregation. TXB2 alone induced a microaggregation behavior of hemocytes under in vitro conditions. Indeed, TXB2 titer was significantly increased in the plasma of the infected larvae. The elevated TXB2 level was further supported by the induction of phospholipase A2 (PLA2) activity in the hemocytes and subsequent up-regulation of COX-like peroxinectins (SePOX-F and SePOX-H) in response to the fungal infection. Finally, the expression of a thromboxane synthase (Se-TXAS) gene was highly expressed in the hemocytes. RNA interference (RNAi) of Se-TXAS expression inhibited the Ca2+ signal and hemocyte aggregation around fungal hyphae, which were rescued by the addition of TXB2. Without any ortholog to mammalian thromboxane receptors, a prostaglandin receptor was essential to mediate TXB2 signal to elevate the Ca2+ signal and mediate hemocyte aggregation behavior. Specific inhibitor assays suggest that the downstream signal after binding TXB2 to the receptor follows the Ca2+-induced Ca2+ release pathway from the endoplasmic reticulum of the hemocytes. These results suggest that hemocyte aggregation induced by the fungal infection is triggered by TXB2via a Ca2+ signal through a PG receptor.
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Affiliation(s)
- Miltan Chandra Roy
- Department of Plant Medicals, Andong National University, Andong, South Korea
| | - Kiwoong Nam
- DGIMI, Univ Montpellier, INRAE, Montpellier, France
| | - Jaesu Kim
- Department of Agricultural Convergence Technology, Jeonbuk National University, Jeonju, South Korea
| | - David Stanley
- Biological Control of Insect Research Laboratory, United States Department of Agriculture-Agricultural Research Station (USDA/ARS), Columbia, MO, United States
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, South Korea
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Ji JY, Yin ZH, Zhang SS, Shen DX, An CJ. PLA 2 mediates the innate immune response in Asian corn borer, Ostrinia furnacalis. INSECT SCIENCE 2022; 29:245-258. [PMID: 34080301 DOI: 10.1111/1744-7917.12932] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 03/27/2021] [Accepted: 04/05/2021] [Indexed: 06/12/2023]
Abstract
The eicosanoid signaling pathway mediates insect immune reactions to a wide range of stimuli. This pathway begins with the biosynthesis of arachidonic acid (AA) from the hydrolysis of phospholipids catalyzed by phospholipase A2 (PLA2 ). We report here that the PLA2 inhibitor, dexamethasone (DEX), impaired the innate immune response including nodulation, encapsulation, and melanization in Ostrinia furnacalis larvae, while AA partially reversed these effects of DEX. We cloned a full-length complementary DNA encoding a PLA2 , designated as OfsPLA2 , from O. furnacalis. The open reading frame of OfsPLA2 encodes a 195-amino acid residue protein with a 22-residue signal peptide. Sequence alignment analyses indicated that O. furnacalis PLA2 might be a Group III secretory PLA2 . The highest transcript levels of OfsPLA2 were detected in the fat body, and its transcript levels increased dramatically after infection with Escherichia coli, Micrococcus luteus, or Beauveria bassiana. Recombinant OfsPLA2 significantly induced prophenoloxidase (PPO) activation in larval hemolymph in the presence of Ca2+ and encapsulation of agarose beads. Injection of recombinant OfsPLA2 into larvae resulted in increased transcript levels of attacin, defencin, and moricin-3 genes. Our results demonstrate the involvement of the eicosanoid signaling pathway in the innate immune response of O. furnacalis larvae and provide new information about the roles of O. furnacalis secretory PLA2 in activating PPO and antimicrobial peptide production.
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Affiliation(s)
- Jia-Yue Ji
- Department of Entomology, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Zhao-Hua Yin
- Department of Entomology, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Sha-Sha Zhang
- Department of Entomology, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Dong-Xu Shen
- Department of Entomology, College of Plant Protection, China Agricultural University, Beijing, 100193, China
- Jiangsu Key Laboratory of Sericutural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212018, China
- Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu, 212018, China
| | - Chun-Ju An
- Department of Entomology, College of Plant Protection, China Agricultural University, Beijing, 100193, China
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Roy MC, Kim Y. Toll signal pathway activating eicosanoid biosynthesis shares its conserved upstream recognition components in a lepidopteran Spodoptera exigua upon infection by Metarhizium rileyi, an entomopathogenic fungus. J Invertebr Pathol 2021; 188:107707. [PMID: 34952100 DOI: 10.1016/j.jip.2021.107707] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/13/2021] [Accepted: 12/16/2021] [Indexed: 12/20/2022]
Abstract
Eicosanoids play crucial roles in mediating immune responses in insects. Upon a fungal infection, Toll signal pathway can mediate immune responses of Spodoptera exigua, a lepidopteran insect, by activating eicosanoid biosynthesis. However, upstream signal components of the Toll signal pathway activating eicosanoid biosynthesis remain unclear. This study predicted pattern recognition receptors (PRRs) and serine proteases (SPs) as upstream components of the Toll pathway with reference to known signal components of Manduca sexta, another lepidopteran insect. S. exigua infected with Metarhizium rileyi, an entomopathogenic fungus, activated phospholipase A2 (PLA2) and phenoloxidase (PO) enzymes along with marked increases of expression levels of genes encoding three specific antimicrobial peptides, cecropin, gallerimycin, and hemolin. Among ten Toll receptors encoded in the genome of S. exigua, seven Toll genes were associated with immune responses against fungal infection by M. rileyi through individual RNA interference (RNAi) screening. In addition, two Spätzles (ligands of Toll receptor) were required for Toll signaling against the fungal infection. All predicted upstream components of the Toll pathway were inducible by the fungal infection. Individual RNAi screening showed that three PRRs (βGRP-1, βGRP-2, and GNBP3) and five SPs (ModSP, HP21, HP5, HP6, and HP8) were required for immune responses of S. exigua mediated by Toll signal pathway against the fungal infection. However, two PO-activating proteases (PAP1 and PAP3) were not required for PLA2 activation, although they were required for PO activation. These results suggest that PRRs and SPs conserved as upstream components in Toll signal pathway play crucial roles in triggering eicosanoid biosynthesis of S. exigua to mediate various immune responses against fungal infection.
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Affiliation(s)
- Miltan Chandra Roy
- Department of Plant Medicals, Andong National University, Andong 36729, Republic of Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong 36729, Republic of Korea.
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Ahmed S, Kim Y. PGE 2 mediates hemocyte-spreading behavior by activating aquaporin via cAMP and rearranging actin cytoskeleton via Ca 2. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 125:104230. [PMID: 34388674 DOI: 10.1016/j.dci.2021.104230] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/04/2021] [Accepted: 08/08/2021] [Indexed: 06/13/2023]
Abstract
Spreading behavior of hemocytes (= insect blood cells) is essential for cellular immune responses against various microbial pathogens. It is activated by prostaglandin E2 (PGE2) via its membrane receptor associated with secondary messenger, cAMP, in insects. This study observed an increase of calcium ion (Ca2+) level after an acute increase of cAMP induced by PGE2 treatment and clarified the intracellular signals underlying the hemocyte-spreading behavior. Inhibition of Ca2+ flux significantly impaired the hemocyte-spreading and subsequent cellular immune response, phagocytosis. The up-regulation of intracellular Ca2+ in response to PGE2 was dependent on cAMP because RNA interference (RNAi) of PGE2 receptor expression or inhibiting adenylate cyclase prevented Ca2+ mobilization. The up-regulation of Ca2+ was induced by inositol triphosphate (IP3) via its specific IP3 receptor. Furthermore, inhibition of ryanodine receptor impaired Ca2+ mobilization, suggesting Ca2+-induced Ca2+ release. However, the effective spreading behavior of hemocytes was dependent on both secondary messengers. Ca2+ signal stimulated by cAMP was required for activating small G proteins because RNAi treatments of small G proteins such as Rac1, RhoA, and Cdc42 failed to stimulate hemocyte-spreading. In contrast, aquaporin was activated by cAMP. Its activity was necessary for changing cell volume during hemocyte-spreading. These results indicate that PGE2 mediates hemocyte-spreading via cAMP signal to activate aquaporin and via Ca2+ signal to activate actin cytoskeletal rearrangement.
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Affiliation(s)
- Shabbir Ahmed
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea.
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Al Baki MA, Chandra Roy M, Lee DH, Stanley D, Kim Y. The prostanoids, thromboxanes, mediate hemocytic immunity to bacterial infection in the lepidopteran Spodoptera exigua. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 120:104069. [PMID: 33737116 DOI: 10.1016/j.dci.2021.104069] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 03/04/2021] [Accepted: 03/06/2021] [Indexed: 06/12/2023]
Abstract
We report on a new insect prostanoid in a lepidopteran insect, Spodoptera exigua. Thromboxane B2 (TXB2) was detected by LC-MS/MS in extracts of larval epidermis, midgut, fat body and hemocytes, with highest amounts in hemocytes (about 300 ng/g tissue with substantial variation). Thromboxane A2 (TXA2) is an unstable intermediate that is non-enzymatically hydrolyzed into the stable TXB2. In S. exigua, both thromboxanes mediate at least two cellular immune responses to bacterial infection, hemocyte-spreading behavior and nodule formation. At the molecular level, a TXA2 synthase (SeTXAS) was identified from a group of 139 S. exigua cytochrome P450 monooxygenases. SeTXAS was highly similar to mammalian TXAS genes and is expressed in all developmental stages and four tested larval tissues. Immune challenge significantly enhanced SeTXAS expression, especially in hemocytes. RNA interference (RNAi) injections using gene-specific double stranded RNA led to reduced SeTXAS expression and suppressed the cellular immune responses, which were rescued following TXA2 or TXB2 injections. Unlike other PGs, TXA2 or TXB2 did not influence oocyte development in adult females. We infer that thromboxanes are present in insect tissues, where they mediate innate immune responses.
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Affiliation(s)
- Md Abdullah Al Baki
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea
| | - Miltan Chandra Roy
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea
| | - Dong-Hee Lee
- Industry Academy Cooperation Foundation, Andong National University, Andong, 36729, South Korea
| | - David Stanley
- Biological Control of Insect Research Laboratory, USDA/ARS, 1503 South Providence Road, Columbia, MO, 65203, USA
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea.
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Repat33 Acts as a Downstream Component of Eicosanoid Signaling Pathway Mediating Immune Responses of Spodoptera exigua, a Lepidopteran Insect. INSECTS 2021; 12:insects12050449. [PMID: 34069069 PMCID: PMC8156158 DOI: 10.3390/insects12050449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/09/2021] [Accepted: 05/13/2021] [Indexed: 11/17/2022]
Abstract
Repat (=response to pathogen) is proposed for an immune-associated gene family from Spodoptera exigua, a lepidopteran insect. In this gene family, 46 members (Repat1-Repat46) have been identified. They show marked variations in their inducible expression patterns in response to infections by different microbial pathogens. However, their physiological functions in specific immune responses and their interactions with other immune signaling pathways remain unclear. Repat33 is a gene highly inducible by bacterial infections. The objective of this study was to analyze the physiological functions of Repat33 in mediating cellular and humoral immune responses. Results showed that Repat33 was expressed in all developmental stages and induced in immune-associated tissues such as hemocytes and the fat body. RNA interference (RNAi) of Repat33 expression inhibited the hemocyte-spreading behavior which impaired nodule formation of hemocytes against bacterial infections. Such RNAi treatment also down-regulated expression levels of some antimicrobial genes. Interestingly, Repat33 expression was controlled by eicosanoids. Inhibition of eicosanoid biosynthesis by RNAi against a phospholipase A2 (PLA2) gene suppressed Repat33 expression while an addition of arachidonic acid (a catalytic product of PLA2) to RNAi treatment recovered such suppression of Repat33 expression. These results suggest that Repat33 is a downstream component of eicosanoids in mediating immune responses of S. exigua.
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Dalvin S, Eichner C, Dondrup M, Øvergård AC. Roles of three putative salmon louse (Lepeophtheirus salmonis) prostaglandin E 2 synthases in physiology and host-parasite interactions. Parasit Vectors 2021; 14:206. [PMID: 33874988 PMCID: PMC8056522 DOI: 10.1186/s13071-021-04690-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 03/16/2021] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The salmon louse (Lepeophtheirus salmonis) is a parasite of salmonid fish. Atlantic salmon (Salmo salar) exhibit only a limited and ineffective immune response when infested with this parasite. Prostaglandins (PGs) have many biological functions in both invertebrates and vertebrates, one of which is the regulation of immune responses. This has led to the suggestion that prostaglandin E2 (PGE2) is important in the salmon louse host-parasite interaction, although studies of a salmon louse prostaglandin E2 synthase (PGES) 2 gene have not enabled conformation of this hypothesis. The aim of the present study was, therefore, to characterize two additional PGES-like genes. METHODS Lepeophtheirus salmonis microsomal glutathione S-transferase 1 like (LsMGST1L) and LsPGES3L were investigated by sequencing, phylogenetics, transcript localization and expression studies. Moreover, the function of these putative PGES genes in addition to the previously identified LsPGES2 gene was analyzed in double stranded (ds) RNA-mediated knockdown (KD) salmon louse. RESULTS Analysis of the three putative LsPGES genes showed a rather constitutive transcript level throughout development from nauplius to the adult stages, and in a range of tissues, with the highest levels in the ovaries or gut. DsRNA-mediated KD of these transcripts did not produce any characteristic changes in phenotype, and KD animals displayed a normal reproductive output. The ability of the parasite to infect or modulate the immune response of the host fish was also not affected by KD. CONCLUSIONS Salmon louse prostaglandins may play endogenous roles in the management of reproduction and oxidative stress and may be a product of salmon louse blood digestions.
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Affiliation(s)
- Sussie Dalvin
- Institute of Marine Research, SLCR-Sea Lice Research Centre, Nordnes, P. box 1870, 5817, Bergen, Norway
| | - Christiane Eichner
- Department of Biological Sciences, SLCR-Sea Lice Research Centre, University of Bergen, P. box 7803, 5020, Bergen, Norway
| | - Michael Dondrup
- Department of Informatics, SLRC-Sea Lice Research Centre, University of Bergen, P. box 7803, 5020, Bergen, Norway
| | - Aina-Cathrine Øvergård
- Department of Biological Sciences, SLCR-Sea Lice Research Centre, University of Bergen, P. box 7803, 5020, Bergen, Norway.
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Kim Y, Stanley D. Eicosanoid Signaling in Insect Immunology: New Genes and Unresolved Issues. Genes (Basel) 2021; 12:genes12020211. [PMID: 33535438 PMCID: PMC7912528 DOI: 10.3390/genes12020211] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 01/28/2021] [Accepted: 01/28/2021] [Indexed: 12/16/2022] Open
Abstract
This paper is focused on eicosanoid signaling in insect immunology. We begin with eicosanoid biosynthesis through the actions of phospholipase A2, responsible for hydrolyzing the C18 polyunsaturated fatty acid, linoleic acid (18:2n-6), from cellular phospholipids, which is subsequently converted into arachidonic acid (AA; 20:4n-6) via elongases and desaturases. The synthesized AA is then oxygenated into one of three groups of eicosanoids, prostaglandins (PGs), epoxyeicosatrienoic acids (EETs) and lipoxygenase products. We mark the distinction between mammalian cyclooxygenases and insect peroxynectins, both of which convert AA into PGs. One PG, PGI2 (also called prostacyclin), is newly discovered in insects, as a negative regulator of immune reactions and a positive signal in juvenile development. Two new elements of insect PG biology are a PG dehydrogenase and a PG reductase, both of which enact necessary PG catabolism. EETs, which are produced from AA via cytochrome P450s, also act in immune signaling, acting as pro-inflammatory signals. Eicosanoids signal a wide range of cellular immune reactions to infections, invasions and wounding, including nodulation, cell spreading, hemocyte migration and releasing prophenoloxidase from oenocytoids, a class of lepidopteran hemocytes. We briefly review the relatively scant knowledge on insect PG receptors and note PGs also act in gut immunity and in humoral immunity. Detailed new information on PG actions in mosquito immunity against the malarial agent, Plasmodium berghei, has recently emerged and we treat this exciting new work. The new findings on eicosanoid actions in insect immunity have emerged from a very broad range of research at the genetic, cellular and organismal levels, all taking place at the international level.
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Affiliation(s)
- Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, Korea
- Correspondence:
| | - David Stanley
- Biological Control of Insects Research Laboratory, USDA/Agricultural Research Service, 1503 South Providence Road, Columbia, MO 65203, USA;
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Characterization of prostanoid pathway and the control of its activity by the eyestalk optic ganglion in the female giant freshwater prawn, Macrobrachium rosenbergii. Heliyon 2021; 7:e05898. [PMID: 33553720 PMCID: PMC7851786 DOI: 10.1016/j.heliyon.2021.e05898] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 10/24/2020] [Accepted: 12/31/2020] [Indexed: 12/28/2022] Open
Abstract
The giant freshwater prawn, Macrobrachium rosenbergii, is an economically valuable species that are distributed throughout the Asia-Pacific region. With the natural population declining due to overfishing, aquaculture of this species is deemed necessary. Hence, it is essential to understand the mechanisms regulating reproduction in order to increase their production. Prostaglandins (PGs) play an important role in reproduction in most vertebrates and several invertebrates. It has been proposed that crustaceans have PGs but the prostanoids pathway in the giant freshwater prawn is still unclear. In this study, we identified 25 prostanoid-related genes involved in the biosynthesis of active prostanoids in M. rosenbergii using in silico searches of transcriptome data. Comparative analysis of encoded proteins for the MroPGES2 gene with other species was performed to confirm their evolutionary conservation. Gene expression analysis revealed the correlation of MroPGES2 gene expression level with the progress of ovarian development. Eyestalk ablation increased the expression level of MroPGES2 gene compared to intact groups during the ovary maturation stages. Collectively, this study confirmed the existence of prostanoids in the giant freshwater prawn, as well as characterizing key gene MroPGES2 associated with the prostanoid pathway. We propose that MroPGES2 may play an important role in M. rosenbergii ovarian maturation and its expression is under the inhibitory control from the eyestalk optic ganglion hormones. Identification of genes in prostanoid pathway and their expressions enables future functional studies to be performed, which may lead to applications in the aquaculture of this species.
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IRP30 promotes worker egg-laying in bumblebee, Bombus terrestris (Hymenoptera: Apidae). Gene 2021; 776:145446. [PMID: 33484761 DOI: 10.1016/j.gene.2021.145446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 11/16/2020] [Accepted: 01/13/2021] [Indexed: 11/22/2022]
Abstract
Bumblebees are important pollinators that have evolved between solitary and advanced eusocial insects. Compared with advanced honeybees, workers of social bumblebee species are prone to laying eggs during the competition phase, which leads to the end of the colony. Therefore, worker reproductive behavior has become a popular research topic for exploring various biological phenomena. Here, we demonstrate a novel reproduction-related function of an immune response protein-encoding gene (Immune Responsive Protein 30, IRP30) in Bombus terrestris by employing RNA interference (RNAi) and a transgenic Drosophila melanogaster system. The results show that worker egg-laying was significantly affected by IRP30 expression levels (P < 0.01). Compared with those in the dsGFP-treated groups, the first egg-laying time was delayed by 3.7 d and the egg number was decreased by 41% in the dsIRP30-treated group. In addition, the average size of the largest oocyte and the relative mRNA expression levels of Vg (vitellogenin) were significantly reduced in the dsIRP30-treated group (P < 0.05). Cellular localization by immunofluorescence demonstrated that IRP30 has important functions in the germ cells of workers' ovarioles. Overexpression of IRP30 was confirmed to increase the reproductive capability of the transgenic D. melanogaster. In conclusion, IRP30 regulates worker egg-laying by affecting the expression of Vg, the size of the ovary and the formation of the oocyte. These findings provide essential information for understanding the mechanisms underlying worker reproductive regulation.
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Ahmed S, Al Baki MA, Lee J, Seo DY, Lee D, Kim Y. The first report of prostacyclin and its physiological roles in insects. Gen Comp Endocrinol 2021; 301:113659. [PMID: 33166533 DOI: 10.1016/j.ygcen.2020.113659] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 11/03/2020] [Accepted: 11/04/2020] [Indexed: 12/13/2022]
Abstract
Prostaglandins (PGs) mediate physiological processes of insects as well as mammals. Prostaglandin I2 (PGI2) is a relatively well-known eicosanoid with potent hormone-like actions on various tissues of vertebrates, however, its presence and biosynthetic pathway have not been described in insects. This study demonstrated that fat bodies of the lepidopteran species, Spodoptera exigua, contained ~ 3.6 pg/g PGI2. To identify its biosynthetic pathway, a PGI2 synthase gene of S. exigua (Se-PGIS) was predicted from a transcriptome of S. exigua; 25.6% homology with human PGIS was demonstrated. Furthermore, a predicted three-dimensional structure of Se-PGIS was demonstrated to be 38.3% similar to the human PGIS ortholog, including catalytic residues. Se-PGIS was expressed in all developmental stages of S. exigua and most abundant larval and adult stages; immune challenging of larvae significantly up-regulated these expression levels. The inducible expression of Se-PGIS expression was followed by a greater than four-fold increase in the concentration of PGI2 in fat bodies 10 h after immune challenge. RNA interference (RNAi) against Se-PGIS was performed by injecting double-stranded RNA (dsRNA). Under these RNAi conditions, cellular immune responses (e.g., hemocyte-spreading behavior, nodulation, phenoloxidase activity) were not affected by bacterial challenge. The addition of PGI2 to larvae treated with an eicosanoid biosynthesis inhibitor did not rescue the immunosuppression. Interestingly, PGI2 injection significantly suppressed nodule formation in response to bacterial challenge. In addition to the negative effect of PGI2 against immunity, the Se-PGIS-RNAi treatment significantly interfered with immature development and severely impaired oocyte development in female adults; the addition of PGI2 to RNAi-treated females significantly recovered oocyte development. Se-PGIS RNAi treatment also impaired male fertility by reducing fecundity after mating with untreated females. These results suggest that PGI2 acts as a negative regulator of immune responses initiated by other factors and mediates S. exigua development and reproduction.
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Affiliation(s)
- Shabbir Ahmed
- Department of Plant Medicals, Andong National University, Andong 36729, Republic of Korea
| | - Md Abdullah Al Baki
- Department of Plant Medicals, Andong National University, Andong 36729, Republic of Korea
| | - Junbeom Lee
- Metabolomics Research Center for Functional Materials, Kyungsung University, Busan 48434, Republic of Korea
| | - Dong Yeon Seo
- Metabolomics Research Center for Functional Materials, Kyungsung University, Busan 48434, Republic of Korea
| | - Daeweon Lee
- Metabolomics Research Center for Functional Materials, Kyungsung University, Busan 48434, Republic of Korea; Department of Biology, Kyungsung University, Busan 48434, Republic of Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong 36729, Republic of Korea.
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Ahmed S, Seo K, Kim Y. An ovary-specific mucin is associated with choriogenesis mediated by prostaglandin signaling in Spodoptera exigua. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2021; 106:e21748. [PMID: 33038048 DOI: 10.1002/arch.21748] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/26/2020] [Accepted: 09/27/2020] [Indexed: 06/11/2023]
Abstract
Polytrophic ovarioles of Spodoptera exigua, a lepidopteran insect, begins with the development of oocytes and differentiation of nurse cells followed by vitellogenesis and choriogenesis. Compared with previtellogenic and vitellogenic developments, choriogenesis has not been clearly understood yet in endocrine control. This study investigated the expression and function of a mucin-like structural protein of S. exigua called Se-Mucin1 in choriogenesis. It was highly expressed in ovarioles containing chorionated oocytes. The expression level of Se-Mucin1 was increased during adult stage as early as 18 h after adult emergence, reaching the maximal level at 24 h and later. Interestingly, DNA amount of Se-Mucin1 was increased by almost four folds during early adult stage while other genes (hexokinase and glyceraldehyde-3-phosphate dehydrogenase) not directly associated with chorion formation did not show genomic DNA increase, suggesting specific gene amplification of Se-Mucin1. RNA interference (RNAi) suppressed Se-Mucin1 expression by injecting 1 μg of double-strand RNA to teneral females (<5 h after emergence), which exhibited significantly impaired fecundity and egg hatching rate. Eggs laid by RNAi-treated females were malformed in eggshell structures with loss of mesh-like fibers. Treatment with aspirin, a prostaglandin (PG) biosynthesis inhibitor, suppressed the induction of Se-Mucin1 expression during early adult stage and impaired egg development. An addition of PGE2 significantly rescued such impairment in Se-Mucin1 expression and subsequent egg development. These results suggest that PGs mediate choriogenesis of S. exigua by activating the expression of chorion-associated genes including Se-Mucin1.
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Affiliation(s)
- Shabbir Ahmed
- Department of Plant Medicals, Andong National University, Andong, Korea
| | - Kiwon Seo
- Department of Plant Medicals, Andong National University, Andong, Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, Korea
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Ahmed S, Kim Y. Prostaglandin catabolism in Spodoptera exigua, a lepidopteran insect. J Exp Biol 2020; 223:jeb233221. [PMID: 32978320 DOI: 10.1242/jeb.233221] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 09/18/2020] [Indexed: 08/25/2023]
Abstract
Several prostaglandins (PGs) and PG-synthesizing enzymes have been identified from insects. PGs mediate cellular and humoral immune responses. However, uncontrolled and prolonged immune responses might have adverse effects on survival. PG catabolism in insects has not been reported. Here, using a transcriptomic analysis, we predicted the presence of two PG-degrading enzymes, PG dehydrogenase (SePGDH) and PG reductase (SePGR), in Spodoptera exigua, a lepidopteran insect. SePGDH and SePGR expression levels were upregulated after immune challenge. However, their expression peaks occurred after those of PG biosynthesis genes, such as those encoding PGE2 synthase or PGD2 synthase. SePGDH and SePGR expression levels were upregulated after injection with PGE2 or PGD2 In contrast, such upregulated expression was not detected after injection with leukotriene B4, an eicosanoid inflammatory mediator. RNA interference (RNAi) using double-stranded RNAs specific to SePGDH or SePGR suppressed their expression levels. The RNAi treatment resulted in an excessive and fatal melanization of larvae even after a non-pathogenic bacterial infection. Phenoloxidase (PO) activity mediating the melanization in larval plasma was induced by bacterial challenge or PGE2 injection. Although the induced PO activity decreased after 8 h in control larvae, those treated with dsRNAs specific to PG-degrading enzyme genes kept a high PO activity for a longer period. These results suggest that SePGDH and SePGR are responsible for PG degradation at a late phase of the immune response.
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Affiliation(s)
- Shabbir Ahmed
- Department of Plant Medicals, Andong National University, Andong 36729, Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong 36729, Korea
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Barletta ABF, Alves e Silva TL, Talyuli OAC, Luna-Gomes T, Sim S, Angleró-Rodríguez Y, Dimopoulos G, Bandeira-Melo C, Sorgine MHF. Prostaglandins regulate humoral immune responses in Aedes aegypti. PLoS Negl Trop Dis 2020; 14:e0008706. [PMID: 33095767 PMCID: PMC7584201 DOI: 10.1371/journal.pntd.0008706] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 08/12/2020] [Indexed: 02/01/2023] Open
Abstract
Prostaglandins (PGs) are immuno-active lipids that mediate the immune response in invertebrates and vertebrates. In insects, PGs play a role on different physiological processes such as reproduction, ion transport and regulation of cellular immunity. However, it is unclear whether PGs play a role in invertebrate's humoral immunity, and, if so, which immune signaling pathways would be modulated by PGs. Here, we show that Aedes aegypti gut microbiota and Gram-negative bacteria challenge induces prostaglandin production sensitive to an irreversible inhibitor of the vertebrate cyclooxygenase, acetylsalicylic acid (ASA). ASA treatment reduced PG synthesis and is associated with decreased expression of components of the Toll and IMD immune pathways, thereby rendering mosquitoes more susceptible to both bacterial and viral infections. We also shown that a cytosolic phospholipase (PLAc), one of the upstream regulators of PG synthesis, is induced by the microbiota in the midgut after blood feeding. The knockdown of the PLAc decreased prostaglandin production and enhanced the replication of Dengue in the midgut. We conclude that in Ae. aegypti, PGs control the amplitude of the immune response to guarantee an efficient pathogen clearance.
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Affiliation(s)
- Ana Beatriz Ferreira Barletta
- Laboratório de Bioquímica de Artrópodes Hematófagos, Instituto de Bioquímica Médica Leopoldo De Meis, Programa de Biologia Molecular e Biotecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Brasil
| | - Thiago Luiz Alves e Silva
- Laboratório de Bioquímica de Artrópodes Hematófagos, Instituto de Bioquímica Médica Leopoldo De Meis, Programa de Biologia Molecular e Biotecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Brasil
| | - Octavio A. C. Talyuli
- Laboratório de Bioquímica de Artrópodes Hematófagos, Instituto de Bioquímica Médica Leopoldo De Meis, Programa de Biologia Molecular e Biotecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil
| | - Tatiana Luna-Gomes
- Departamento de Ciências da Natureza, Instituto de Aplicação Fernando Rodrigues da Silveira (CAp-UERJ), Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brasil
| | - Shuzhen Sim
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Yesseinia Angleró-Rodríguez
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - George Dimopoulos
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Christianne Bandeira-Melo
- Laboratório de Inflamação, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil
| | - Marcos H. Ferreira Sorgine
- Laboratório de Bioquímica de Artrópodes Hematófagos, Instituto de Bioquímica Médica Leopoldo De Meis, Programa de Biologia Molecular e Biotecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Brasil
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Kim Y, Ahmed S, Al Baki MA, Kumar S, Kim K, Park Y, Stanley D. Deletion mutant of PGE 2 receptor using CRISPR-Cas9 exhibits larval immunosuppression and adult infertility in a lepidopteran insect, Spodoptera exigua. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2020; 111:103743. [PMID: 32464135 DOI: 10.1016/j.dci.2020.103743] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 05/06/2020] [Accepted: 05/08/2020] [Indexed: 06/11/2023]
Abstract
Prostaglandins (PGs) mediate various physiological processes in insects and other invertebrates, but there is very little information on PG receptors. This study identified a PGE2 receptor (SePGE2R) in the lepidopteran insect, Spodoptera exigua, and addressed its functional association with cellular immunity, development, and reproduction. SePGE2R is expressed in most developmental stages and tissues. After SePGR2R expression knock down by RNA interference (RNAi), larval nodule formation (clears bacterial infections from circulating hemolymph) was severely suppressed coupled with reduced F-actin growth in hemocytes. Treating female adults with RNAi prevented nurse cell dumping in follicles and interfered with oocyte development. SePGE2R was heterologously expressed in Sf9 cells, in which the endogenous S. frugiperda PGE2R was knocked down by small interfering RNA. This transiently expressed SePGE2R responded to PGE2, but not other PGs, with dose-dependent up-regulation of intracellular cAMP concentrations. Treating S. exigua larvae with PGE2 led to activation of a trimeric Gαs subunit, protein kinase A (PKA), and Rho family small intracellular G proteins in hemocytes. A deletion mutant of SePGE2R was generated using CRISPR/Cas9 which exhibited severely retarded larval development and adult reproduction. We infer that PGE2R mediates insect immune and reproductive processes via a PKA signal pathway.
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Affiliation(s)
- Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, South Korea.
| | - Shabbir Ahmed
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, South Korea
| | - Md Abdullah Al Baki
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, South Korea
| | - Sunil Kumar
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, South Korea; Department of Biological Sciences, Sungkyunkwan University, Suwon, 440-746, South Korea
| | - Kunwoo Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, South Korea
| | - Youngjin Park
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, South Korea; Plant Quarantine Technology Center, Animal and Plant Quarantine Agency, Gimcheon, 39660, South Korea
| | - David Stanley
- Biological Control of Insect Research Laboratory, USDA/Agricultural Research Service, Colombia, MO, USA
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Roy MC, Kim Y. sPLA 2 behaves like a prophylactic agent and mediates cellular and humoral immune responses in Plutella xylostella. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2020; 104:e21670. [PMID: 32196735 DOI: 10.1002/arch.21670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 03/07/2020] [Accepted: 03/10/2020] [Indexed: 06/10/2023]
Abstract
Most immune effectors are inducible to microbial pathogen infection while some are already present to act as prophylactic immunity against as yet unseen infection. This study identified secretory phospholipase A2 (sPLA2 ) as a prophylactic factor in diamondback moth, Plutella xylostella. Western blotting using a polyclonal antibody raised against other lepidopteran sPLA2 reacted specifically with ∼25 kDa protein, which was present at approximately 0.4 mM in the plasma of naïve larvae. Interrogation of P. xylostella transcriptomes revealed an open-reading frame for sPLA2 (Px-sPLA2 ), exhibiting high homology with other Group III sPLA2 s. Px-sPLA2 was expressed in all developmental stages. In the larval stage, bacterial challenge induced its expression in hemocytes and fat body but not in gut or epidermis. RNA interference (RNAi) suppressed Px-sPLA2 messenger RNA level and sPLA2 activity in plasma. An inhibition zone assay showed that Px-sPLA2 exhibited antibacterial activities against different species, because specific RNAi knockdown impaired the activity. The RNAi treatment also suppressed the cellular immune response assessed by hemocyte nodule formation and humoral immune response assessed by antimicrobial peptide gene expression. Finally, benzylideneacetone (BZA, a specific sPLA2 inhibitor) treatment inhibited plasma sPLA2 activity of naive larvae in a dose-dependent manner. An addition of BZA significantly increased the bacterial virulence of an entomopathogen, Bacillus thuringiensis. These results suggest that Px-sPLA2 is an immune-associated factor of P. xylostella and its relatively high level of concentration in the plasma of naive larvae strongly suggests its role as a prophylactic factor in defending against pathogens at early infection stages.
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Affiliation(s)
- Miltan Chandra Roy
- Department of Plant Medicals, Andong National University, Andong, South Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, South Korea
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Kwon H, Yang Y, Kumar S, Lee DW, Bajracharya P, Calkins TL, Kim Y, Pietrantonio PV. Characterization of the first insect prostaglandin (PGE 2) receptor: MansePGE 2R is expressed in oenocytoids and lipoteichoic acid (LTA) increases transcript expression. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2020; 117:103290. [PMID: 31790798 DOI: 10.1016/j.ibmb.2019.103290] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 11/22/2019] [Accepted: 11/26/2019] [Indexed: 06/10/2023]
Abstract
In arthropods, eicosanoids derived from the oxygenated metabolism of arachidonic acid are significant in mediating immune responses. However, the lack of information about insect eicosanoid receptors is an obstacle to completely decipher immune mechanisms underlying both eicosanoid downstream signal cascades and their relationship to immune pathogen-associated molecular patterns (PAMPs). Here, we cloned and sequenced a G protein-coupled receptor (MW 46.16 kDa) from the model lepidopteran, Manduca sexta (Sphingidae). The receptor shares similarity of amino acid motifs to human prostaglandin E2 (PGE2) receptors, and phylogenetic analysis supports its classification as a prostaglandin receptor. In agreement, the recombinant receptor was activated by PGE2 resulting in intracellular cAMP increase, and therefore designated MansePGE2R. Expression of MansePGE2R in Sf9 cells in which the endogenous orthologous receptor had been silenced showed similar cAMP increase upon PGE2 challenge. Receptor transcript expression was identified in various tissues in larvae and female adults, including Malpighian tubules, fat body, gut and hemocytes, and in female ovaries. In addition to the cDNA cloned that encodes the functional receptor, an mRNA was found featuring the poly-A tail but lacking the predicted transmembrane (TM) regions 2 and 3, suggesting the possibility that internally deleted receptor proteins exist in insects. Immunocytochemistry and in situ hybridization revealed that among hemocytes, the receptor was exclusively localized in the oenocytoids. Larval immune challenges injecting bacterial components showed that lipoteichoic acid (LTA) increased MansePGE2R expression in hemocytes. In contrast, injection of LPS or peptidoglycan did not increase MansePGE2R transcript levels in hemocytes, suggesting the LTA-associated increase in receptor transcript is regulated through a distinct pathway. This study provides the first characterization of an eicosanoid receptor in insects, and paves the way for establishing the hierarchy in signaling steps required for establishing insect immune responses to infections.
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Affiliation(s)
- Hyeogsun Kwon
- Department of Entomology, Texas A&M University, College Station, TX, 77843-2475, USA.
| | - Yunlong Yang
- Department of Entomology, Texas A&M University, College Station, TX, 77843-2475, USA.
| | - Sunil Kumar
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea.
| | - Dae-Weon Lee
- Department of Entomology, Texas A&M University, College Station, TX, 77843-2475, USA.
| | - Prati Bajracharya
- Department of Entomology, Texas A&M University, College Station, TX, 77843-2475, USA.
| | - Travis L Calkins
- Department of Entomology, Texas A&M University, College Station, TX, 77843-2475, USA.
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea.
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Sajjadian SM, Ahmed S, Al Baki MA, Kim Y. Prostaglandin D 2 synthase and its functional association with immune and reproductive processes in a lepidopteran insect, Spodoptera exigua. Gen Comp Endocrinol 2020; 287:113352. [PMID: 31794733 DOI: 10.1016/j.ygcen.2019.113352] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 11/29/2019] [Accepted: 11/29/2019] [Indexed: 12/21/2022]
Abstract
Several prostaglandins (PGs) have been identified in different insect species. However, their biosynthesis and physiological roles in insects remain unclear. PGD2 is synthesized by isomerization from PGH2 in mammals. This study identified a PGD2 synthase (SePGDS) in a lepidopteran insect, Spodoptera exigua. It showed sequence homology (32.8%) with human PGDS. Based on its conserved active site residues, its N-terminal tyrosine (Y8) was predicted to mediate electron relay from glutathione to PGH2 substrate, which was distinct from the catalysis of PGE2 (=PGD2 isomer) synthase (SePGES). SePGDS was highly expressed in larval and adult stages. RNA interference (RNAi) of SePGDS expression resulted in immunosuppression of cellular immune responses by suppressing the expression of actin polymerization-associated genes. It also suppressed the expression of some antimicrobial genes. Such immunosuppression induced by RNAi treatment was specifically rescued by the addition of PGD2, but not its precursor, arachidonic acid. Such RNAi treatment in adults prevented egg development in females by inhibiting choriogenesis. RNAi treatment also suppressed nurse cell dumping to growing oocytes. However, the addition of PGD2 rescued egg development of RNAi-treated females. These results suggest that SePGDS is responsible for the production of PGD2 which mediates immune and reproductive processes of S. exigua.
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Affiliation(s)
- Seyede Minoo Sajjadian
- Department of Plant Medicals, Andong National University, Andong 36729, Republic of Korea
| | - Shabbir Ahmed
- Department of Plant Medicals, Andong National University, Andong 36729, Republic of Korea
| | - Md Abdullah Al Baki
- Department of Plant Medicals, Andong National University, Andong 36729, Republic of Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong 36729, Republic of Korea.
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Md Abdullah AB, Lee DW, Jung J, Kim Y. Deletion mutant of sPLA 2 using CRISPR/Cas9 exhibits immunosuppression, developmental retardation, and failure of oocyte development in legume pod borer, Maruca vitrata. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2020; 103:103500. [PMID: 31589887 DOI: 10.1016/j.dci.2019.103500] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 09/24/2019] [Accepted: 09/24/2019] [Indexed: 06/10/2023]
Abstract
Phospholipase A2 (PLA2) catalyzes release of free fatty acids linked to phospholipids at sn-2 position. Some of these released free fatty acids are used to synthesize eicosanoids that mediate various physiological processes in insects. Although a large number of PLA2s form a superfamily consisting of at least 16 groups, few PLA2s have been identified and characterized in insects. Furthermore, physiological functions of insect PLA2s remain unclear. Clustered regularly interspaced short parlindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) has been a useful research tool to validate gene function. This study identified and characterized a secretory PLA2 (sPLA2) from legume pod borer, Maruca vitrata (Lepidoptera: Crambidae), and validated its physiological functions using CRISPR/Cas9. An open reading frame of M. vitrata sPLA2 (Mv-sPLA2) encoding 192 amino acids contained signal peptide, calcium-binding domain, and catalytic site. Phylogenetic analysis indicated that Mv-sPLA2 was related to other Group III sPLA2s. Mv-sPLA2 was expressed in both larval and adult stages. It was inducible by immune challenge. RNA interference (RNAi) of Mv-sPLA2 significantly suppressed cellular immunity and impaired larval development. Furthermore, RNAi treatment in female adults prevented oocyte development. These physiological alterations were also observed in a mutant line of M. vitrata with Mv-sPLA2 deleted by using CRISPR/Cas9. Mv-sPLA2 was not detected in the mutant line from western blot analysis. Addition of an eicosanoid, PGE2, significantly rescued oocyte development of females of the mutant line. These results suggest that Mv-sPLA2 plays crucial role in immune, developmental, and reproductive processes of M. vitrata.
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Affiliation(s)
- Al Baki Md Abdullah
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea
| | - Dae-Weon Lee
- School of Chemistry and Life Sciences, Kyungsung University, Busan, 48434, South Korea
| | - Jinkyo Jung
- Division of Crop Cultivation and Environment Research, Department of Central Area Crop Science, National Institute of Crop Science, Rural Development Administration, Suwon, 16429, South Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea.
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Ahmed S, Kim Y. PGE 2 mediates cytoskeletal rearrangement of hemocytes via Cdc42, a small G protein, to activate actin-remodeling factors in Spodoptera exigua (Lepidoptera: Noctuidae). ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2019; 102:e21607. [PMID: 31338878 DOI: 10.1002/arch.21607] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/09/2019] [Accepted: 07/10/2019] [Indexed: 06/10/2023]
Abstract
Prostaglandin E2 (PGE2 ) mediates cellular immune responses in insects by stimulating hemocyte-spreading behavior that is driven by actin remodeling to form filopodial or lamellipodial cytoplasmic extensions. In Spodoptera exigua (Lepidoptera: Noctuidae), Cdc42, a small G protein, played a crucial role in mediating PGE2 signal on hemocyte-spreading behavior. Hemocyte-spreading behavior requires actin cytoskeletal rearrangement. A plethora of actin-related proteins have been predicted to have functional links with Cdc42. Here, we selected four actin-associated genes (Actin-related protein 2 [Arp2], Profilin, Cofilin, and Fascin) and evaluated their influences on cytoskeletal rearrangement in S. exigua. Bioinformatic analysis confirmed their gene identities. Transcript analysis using reverse-transcription polymerase chain reaction indicated that all four actin-associated genes were expressed in most developmental stages, showing high expression levels in larval hemocytes. RNA interference (RNAi) against these genes was performed by injecting double-stranded RNA (dsRNA) to hemocoel. Under RNAi condition, the hemocyte-spreading behavior was significantly impaired except for dsRNA treatment against Cofilin, an actin-depolymerizing factor. Alteration of cytoskeletal rearrangement appeared to vary after different RNAi treatments. RNAi against Arp2 markedly suppressed lamellipodial extension while RNAi against Profilin or Fascin adversely influenced filopodial extension. RNAi of these actin-associated factors prevented cellular immune responses measured by nodule formation against bacterial challenge. Under RNAi conditions, addition of PGE2 did not well induce hemocyte-spreading behavior, suggesting that these actin-associated factors might act downstream of the hormone signaling pathway. These results suggest that PGE2 can mediate hemocyte-spreading behavior via Cdc42 to activate downstream actin polymerization/branching/bundling factors, thus inducing actin cytoskeletal rearrangement.
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Affiliation(s)
- Shabbir Ahmed
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Korea
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Korea
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Biwot JC, Zhang HB, Chen MY, Wang YF. A new function of immunity-related gene Zn72D in male fertility of Drosophila melanogaster. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2019; 102:e21612. [PMID: 31482645 DOI: 10.1002/arch.21612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 07/21/2019] [Accepted: 08/16/2019] [Indexed: 06/10/2023]
Abstract
Zn72D encodes the Drosophila zinc finger protein Zn72D. It was first identified to be involved in phagocytosis and indicated to have a role in immunity. Then it was demonstrated to have a function in RNA splicing and dosage compensation in Drosophila melanogaster. In this study, we discovered a new function of Zn72D in male fertility. We showed that knockdown of Zn72D in fly testes caused an extremely low egg hatch rate. Immunofluorescence staining of Zn72D knockdown testes exhibited scattered spermatid nuclei and no actin cones or individualization complexes (ICs) during spermiogenesis, whereas the early-stage germ cells and the spermatocytes were observed clearly. There were no mature sperms in the seminal vesicles of Zn72D knockdown fly testes, although a few sperms could be found close to the seminal vesicle. We further showed that many cytoskeleton-related genes were significantly downregulated in fly testes due to Zn72D knockdown. Taken together these findings suggest that Zn72D may have an important function in spermatogenesis by sustaining the cytoskeleton-based morphogenesis and individualization thus ensuring the proper formation of sperm in D. melanogaster.
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Affiliation(s)
- John C Biwot
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Hua-Bao Zhang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Meng-Yan Chen
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Yu-Feng Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
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Inhibitors of Eicosanoid Biosynthesis Reveal that Multiple Lipid Signaling Pathways Influence Malaria Parasite Survival in Anopheles gambiae. INSECTS 2019; 10:insects10100307. [PMID: 31547026 PMCID: PMC6835628 DOI: 10.3390/insects10100307] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 09/16/2019] [Accepted: 09/18/2019] [Indexed: 12/16/2022]
Abstract
Eicosanoids are bioactive signaling lipids derived from the oxidation of fatty acids that act as important regulators of immune homeostasis and inflammation. As a result, effective anti-inflammatory drugs have been widely used to reduce pain and inflammation which target key eicosanoid biosynthesis enzymes. Conserved from vertebrates to insects, the use of these eicosanoid pathway inhibitors offer opportunities to evaluate the roles of eicosanoids in less-characterized insect systems. In this study, we examine the potential roles of eicosanoids on malaria parasite survival in the mosquito Anopheles gambiae. Using Plasmodium oocyst numbers to evaluate parasite infection, general or specific inhibitors of eicosanoid biosynthesis pathways were evaluated. Following the administration of dexamethasone and indomethacin, respective inhibitors of phospholipid A2 (PLA2) and cyclooxygenase (COX), oocyst numbers were unaffected. However, inhibition of lipoxygenase (LOX) activity through the use of esculetin significantly increased oocyst survival. In contrast, 12-[[(tricyclo[3.3.1.13,7]dec-1-ylamino)carbonyl]amino]-dodecanoic acid (AUDA), an inhibitor of epoxide hydroxylase (EH), decreased oocyst numbers. These experiments were further validated through RNAi experiments to silence candidate genes homologous to EH in An. gambiae to confirm their contributions to Plasmodium development. Similar to the results of AUDA treatment, the silencing of EH significantly reduced oocyst numbers. These results imply that specific eicosanoids in An. gambiae can have either agonist or antagonistic roles on malaria parasite survival in the mosquito host.
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Sajjadian SM, Vatanparast M, Kim Y. Toll/IMD signal pathways mediate cellular immune responses via induction of intracellular PLA 2 expression. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2019; 101:e21559. [PMID: 31062425 DOI: 10.1002/arch.21559] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 04/18/2019] [Accepted: 04/19/2019] [Indexed: 06/09/2023]
Abstract
Phospholipase A2 (PLA2 ) hydrolyzes fatty acids from phospholipids at the sn-2 position. Two intracellular PLA2 s, iPLA2 A and iPLA2 B, have been found in Spodoptera exigua. Both are calcium-independent cellular PLA2 . Their orthologs have been found in other insects. These two iPLA2 s are different in ankyrin motif of N terminal region. The objective of this study was to determine whether Toll/immune deficiency (IMD) signal pathways could mediate cellular immune responses via induction of iPLA2 expression. Both iPLA 2 s were expressed in all developmental stages of S. exigua, showing the highest expression in the adult stage. During larval stage, hemocyte is the main tissue showing expression of these iPLA2 s. Both iPLA2 s exhibited similar expression patterns after immune challenge with different microbial pathogens such as virus, bacteria, and fungi. Promoter component analysis of orthologs encoded in S. frugiperda indicated nuclear factor-κB- and Relish-responsible elements on their promoters, suggesting their expression in S. exigua under Toll/IMD immune signaling pathways. RNA interference (RNAi) of MyD88 or Pelle under Toll pathway suppressed inducible expression levels of both iPLA2 s in response to Gram-positive bacteria containing Lys-type peptidoglycan or fungal infection. In contrast, RNAi against Relish under IMD pathway suppressed both iPLA2 s in response to infection with Gram-negative bacteria. Under RNAi conditions, hemocytes significantly lost cellular immune response measured by nodule formation. However, addition of arachidonic acid (a catalytic product of PLA2 ) rescued such immunosuppression. These results suggest that Toll/IMD signal pathways can mediate cellular immune responses via eicosanoid signaling by inducing iPLA2 expression.
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Affiliation(s)
- Seyede Minoo Sajjadian
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Korea
| | - Mohammad Vatanparast
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Korea
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Korea
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Abdullah Al Baki M, Kim Y. Inhibition of prostaglandin biosynthesis leads to suppressed ovarian development in Spodoptera exigua. JOURNAL OF INSECT PHYSIOLOGY 2019; 114:83-91. [PMID: 30872119 DOI: 10.1016/j.jinsphys.2019.03.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 03/08/2019] [Accepted: 03/09/2019] [Indexed: 06/09/2023]
Abstract
Prostaglandins (PGs) are a group of eicosanoids that are C20 oxygenated polyunsaturated fatty acids. PGs can mediate various physiological processes such as immunity, salivary secretion, excretion, and reproduction in insects. The objective of this study was to determine the effect of PG on oocyte development in Spodoptera exigua, a lepidopteran insect known to biosynthesize PGs. Polytrophic ovarioles of S. exigua females exhibited follicle development in germarium, in which oocytes were distinct from nurse cells. During vitellogenesis, nurse cells degenerated by losing cytoplasm called "nurse cell dumping" while oocytes showed increase in cell volume. When PG biosynthesis inhibitors such as ibuprofen or aspirin were applied, nurse cell dumping was not complete and no chorion was formed, thus preventing egg formation. However, addition of PGE2 significantly rescued such inhibition and resumed oocyte development and choriogenesis. To support the observation with genetic factor, RNA interference (RNAi) specific to peroxynectins (Pxts: Se-Pxt1 and Se-Pxt2) known to act as insect cyclooxygenase was performed to suppress PG biosynthesis. Both Se-Pxt1 and Se-Pxt2 were highly expressed in the ovary of control female. RNAi treatment against Se-Pxt1 or Se-Pxt2 specifically suppressed target genes and inhibited oocyte development. Addition of PGE2 to adults treated with RNAi rescued the suppressed development of oocytes. Results of this study suggest that PGs can stimulate oocyte development as autocrine/paracrine mediators of vitellogenesis and choriogenesis in insects.
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Affiliation(s)
- Md Abdullah Al Baki
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, Republic of Korea
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, Republic of Korea.
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Stanley D, Kim Y. Prostaglandins and Other Eicosanoids in Insects: Biosynthesis and Biological Actions. Front Physiol 2019; 9:1927. [PMID: 30792667 PMCID: PMC6375067 DOI: 10.3389/fphys.2018.01927] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 12/21/2018] [Indexed: 12/24/2022] Open
Abstract
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, provides an updated treatment of known insect phospholipase A2 (PLA2), and details 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 (PLs) (< 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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Affiliation(s)
- David Stanley
- Biological Control of Insects Research Laboratory, United States Department of Agriculture – Agricultural Research Service, Columbia, MO, United States
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, South Korea
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Ahmed S, Hasan MA, Kim Y. Overexpression of PGE2 synthase by in vivo transient expression enhances immunocompetency along with fitness cost in a lepidopteran insect. J Exp Biol 2019; 222:jeb.207019. [DOI: 10.1242/jeb.207019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 06/30/2019] [Indexed: 01/04/2023]
Abstract
Prostaglandins (PGs) mediate various physiological functions in insects. Especially, PGE2 is known to mediate immunity and egg-laying behavior in the beet armyworm, Spodoptera exigua. A PGE2 synthase 2 (Se-PGES2) has been identified to catalyze the final step to produce PGE2 in S. exigua. Its expression is inducible in response to immune challenge. Inhibition of the gene expression results in immunosuppression. On the other hand, any physiological alteration induced by its uncontrolled overexpression was not recognized in insects. This study used in vivo transient expression (IVTE) technique to induce overexpression and assessed subsequent physiological alteration in S. exigua. Se-PGES2 was cloned into a eukaryotic expression vector and transfected to Sf9 cells to monitor its heterologous expression. The Sf9 cells expressed the recombinant Se-PGES2 (rSe-PGES2) at an expected size (∼47 kDa), which was localized in cytoplasm. The recombinant expression vector was then used to transfect larvae of S. exigua. Hemocytes collected from the larvae treated with IVTE expressed rSe-PGES2 gene for at least 48 h. The larvae treated with IVTE exhibited an enhanced competency in cellular immune response measured by hemocyte nodule formation. In addition, IVTE treatment of Se-PGES2 induced gene expression of antimicrobial peptides without any immune challenge. The larvae treated with IVTE became significantly resistant to infection of an entomopathogenic nematode, Steinernema monticolum or to infection to its symbiotic bacterium, Xenorhabdus hominickii. However, IVTE-treated S. exigua larvae suffered from reduced pupal size and fecundity.
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Affiliation(s)
- Shabbir Ahmed
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, Korea
| | - Md Ariful Hasan
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, Korea
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, Korea
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