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Shahmohammadi N, Esmaeily M, Abdisa E, Mandal E, Kim Y. Enhanced baculoviral virulence by suppressing the degradation of an insect immune resolvin, epoxyoctadecamonoenoic acid, in three lepidopteran insects. J Invertebr Pathol 2024; 204:108095. [PMID: 38499284 DOI: 10.1016/j.jip.2024.108095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 02/17/2024] [Accepted: 03/10/2024] [Indexed: 03/20/2024]
Abstract
Epoxyoctadecamonoenoic acids (EpOMEs) are produced from linoleic acid by a cytochrome P450 monooxygenase (CYP) and play a crucial role in terminating excessive and unnecessary immune responses during the late infection stage in insects. This suggests that an increase in the EpOME level may enhance the virulence of insect pathogens against pests. This study tested this hypothesis using a specific inhibitor against soluble epoxide hydrolase (sEH) to degrade EpOMEs, which leads to elevated endogenous EpOME levels. A baculovirus, Autographa californica multiple nucleopolyhedrovirus (AcMNPV), was used to infect three different lepidopteran insects (Spodoptera exigua, Maruca vitrata, and Plutella xylostella) by oral feeding or hemocoelic injection treatments. Within one hour, the viral infection induced the expression of three different phospholipase A2 (PLA2) genes and, after 12 h, up-regulated the expressions of CYP and sEH genes in Spodopera exigua. As expected, AcMNPV virulence was suppressed by the addition of arachidonic acid (a catalytic product of PLA2) but was enhanced by the addition of either of the EpOME regioisomers. In addition, treatment with a specific sEH inhibitor (AUDA) increased AcMNPV virulence against three different lepidopteran insects, presumably by increasing endogenous EpOME levels. This enhanced effect of EpOMEs on virulence was further supported by specific RNA interference (RNAi), in which RNAi specific to CYP expression decreased AcMNPV virulence while a specific RNAi against sEH expression significantly enhanced virulence. In response to AcMNPV infection, TUNEL assay results showed that S. exigua larvae exhibited apoptosis in the midgut, fat body, and epidermis. Inhibition of apoptosis by a pan-caspase inhibitor, Z-VAD-FMK, significantly increased virulence. Similarly, the addition of AUDA to the viral treatment suppressed the gene expression of five inducible caspases and cytochrome C to suppress apoptosis, which led to a significant increase in the tissue viral titers. These results indicate that EpOMEs play a role in terminating excessive and unnecessary immune responses against viral infection during the late stage by down-regulating antiviral apoptosis in lepidopteran insects.
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Affiliation(s)
| | - Mojtaba Esmaeily
- Department of Plant Medicals, Andong National University, Andong, 36720, Korea
| | - Eticha Abdisa
- Department of Plant Medicals, Andong National University, Andong, 36720, Korea
| | - Eeshita Mandal
- Department of Plant Medicals, Andong National University, Andong, 36720, Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, 36720, Korea.
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2
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Esmaeily M, Kim Y. Four phospholipase A 2 genes encoded in the western flower thrips genome and their functional differentiation in mediating development and immunity. Sci Rep 2024; 14:9766. [PMID: 38684777 PMCID: PMC11059263 DOI: 10.1038/s41598-024-60522-8] [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: 12/14/2023] [Accepted: 04/24/2024] [Indexed: 05/02/2024] Open
Abstract
Eicosanoids are synthesized from phospholipids by the catalytic activity of phospholipase A2 (PLA2). Even though several PLA2s are encoded in the genome of different insect species, their physiological functions are not clearly discriminated. This study identified four PLA2 genes encoded in the western flower thrips, Frankliniella occidentalis. Two PLA2s (Fo-PLA2C and Fo-PLA2D) are predicted to be secretory while the other two PLA2s (Fo-PLA2A and Fo-PLA2B) are intracellular. All four PLA2 genes were expressed in all developmental stages, of which Fo-PLA2B and Fo-PLA2C were highly expressed in larvae while Fo-PLA2A and Fo-PLA2D were highly expressed in adults. Their expressions in different tissues were also detected by fluorescence in situ hybridization. All four PLA2s were detected in the larval and adult intestines and the ovary. Feeding double-stranded RNAs specific to the PLA2 genes specifically suppressed the target transcript levels. Individual RNA interference (RNAi) treatments led to significant developmental retardation, especially in the treatments specific to Fo-PLA2B and Fo-PLA2D. The RNAi treatments also showed that Fo-PLA2B and Fo-PLA2C expressions were required for the induction of immune-associated genes, while Fo-PLA2A and Fo-PLA2D expressions were required for ovary development. These results suggest that four PLA2s are associated with different physiological processes by their unique catalytic activities and expression patterns.
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Affiliation(s)
- Mojtaba Esmaeily
- 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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3
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Abdisa E, Park H, Kwon J, Jin G, Esmaeily M, Kim Y. Enhancement of an entomopathogenic fungal virulence against the seedcorn maggot, Delia platura, by suppressing immune responses with a bacterial culture broth of Photorhabdus temperata subsp. temperata. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2024; 115:e22103. [PMID: 38517449 DOI: 10.1002/arch.22103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 03/01/2024] [Accepted: 03/07/2024] [Indexed: 03/23/2024]
Abstract
In Korea, there are two maggot species in the Delia genus that commonly infest the roots and stems of the Welsh onion, thus causing serious economic damage on the crop at the seedling stage. In this study, the seedcorn maggot (Delia platura) was detected in onion fields in two different localities in Korea. After overwintering, maggot infestations occurred throughout the entire growing seasons from transplantation to harvest, but their specific patterns of occurrence varied in the two localities examined. Entomopathogenic fungi induced significant virulence against the maggot larvae, in which a strain of Beauveria bassiana was effective, though it exhibited limited mortality in its insecticidal activity. To enhance this insecticidal activity, a culture broth from an entomopathogenic bacterium, Photorhabdus temperata temperata (Ptt), was added to B. bassiana treatment. The addition of Ptt broth significantly increased the insecticidal activity of B. bassiana in a dose-dependent manner. To elucidate this enhancement in insecticidal activity, the immunosuppressive activity of Ptt broth was assessed by identifying the immune responses of the seedcorn maggots. The seedcorn maggots possessed at least three different hemocytes with plasmatocytes, crystal cells, and lamellocytes. These hemocytes exhibited nodule formation in response to the fungal infection. In addition to the cellular immunity, the maggots exhibited inducible expressions of antimicrobial peptide (AMP) genes such as cecropin and defensin. The addition of Ptt broth suppressed the nodule formation and the AMP expressions in response to the fungal infection. Altogether, this study demonstrated the innate immune responses in a non-model insect, D. platura, along with the application of immunosuppression to develop a highly efficient biological control by enhancing the virulence of B. bassiana.
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Affiliation(s)
- Eticha Abdisa
- Department of Plant Medicals, Andong National University, Andong, 36729, Korea
| | - Hyunje Park
- Department of Plant Medicals, Andong National University, Andong, 36729, Korea
| | - Jiyoon Kwon
- Department of Plant Medicals, Andong National University, Andong, 36729, Korea
| | - Gahyeon Jin
- Department of Plant Medicals, Andong National University, Andong, 36729, Korea
| | - Mojtaba Esmaeily
- 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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Li T, Wang G, He W, Li G, Wang C, Zhao J, Chen P, Guo M, Chen P. A secreted phospholipase A 2 (BmsPLA 2 ) regulates melanization of immunity through BmDDC in the silkworm Bombyx mori. INSECT SCIENCE 2023; 30:1579-1594. [PMID: 36924440 DOI: 10.1111/1744-7917.13194] [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: 09/24/2022] [Revised: 02/01/2023] [Accepted: 02/27/2023] [Indexed: 06/18/2023]
Abstract
Insect immune-associated phospholipase A2 (PLA2 ) is an important target of pathogen invasion. Melanization, an effective defense response, has significant correlations with other immune responses to coordinate immune attack against invaders. However, the effect of PLA2 on melanization has not yet been reported in insects or other arthropods. In this work, we cloned a PLA2 gene (BmsPLA2 ), and its protein had characteristic features of secreted PLA2 (sPLA2 ). After injection of bacteria, BmsPLA2 expression and sPLA2 activity in hemolymph significantly increased. BmsPLA2 fluorescence was transferred from the cytoplasm to the cell membranes of circulating hemocytes. These results indicated that BmsPLA2 was related to hemolymph immunity in silkworms. Interestingly, reducing BmsPLA2 by RNA interference decreased melanosis (melanistic hemocytes) levels in vivo and in vitro, while BmsPLA2 overexpression had the opposite effect. The larval survival and melanization rate in the hemocoel both slowed depending on the PLA2 inhibitor dosage. These results demonstrated that BmsPLA2 plays a role in melanization during the immune process of silkworms. Surprisingly, the level of BmDDC matched the degree of melanization in various observations. BmDDC expression showed a significant increase, with the peak occurring later than that of BmsPLA2 after injection of bacteria, implying that BmsPLA2 was activated prior to BmDDC. Moreover, the alteration of BmsPLA2 by RNA interference or overexpression led to altered BmDDC levels. These results suggested that BmsPLA2 regulates the melanization response in silkworms through BmDDC. Our study proposes a new regulatory mechanism of the melanization response and new directions for understanding the complex immune networks of insects.
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Affiliation(s)
- Tian Li
- College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
- Drug Discovery Research Center, Southwest Medical University, Luzhou, China
| | - Gemin Wang
- College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Wei He
- College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Guiqin Li
- College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Chunyang Wang
- College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Jiamei Zhao
- College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Pan Chen
- College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Meiwei Guo
- College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Ping Chen
- College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
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Li J, Lyu B, Bi J, Shan R, Stanley D, Feng Q, Song Q. Partner of neuropeptide bursicon homodimer pburs mediates a novel antimicrobial peptide Ten3LP via Dif/Dorsal2 in Tribolium castaneum. Int J Biol Macromol 2023; 247:125840. [PMID: 37454995 DOI: 10.1016/j.ijbiomac.2023.125840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 07/12/2023] [Accepted: 07/13/2023] [Indexed: 07/18/2023]
Abstract
Bursicon is a cystine knot family neuropeptide, composed of two subunits, bursicon (burs) and partner of burs (pburs). The subunits can form heterodimers to regulate cuticle tanning and wing maturation and homodimers to signal different biological functions in innate immunity, midgut stem cell proliferation and energy homeostasis, and reproductive physiology in the model insects Drosophila melanogaster or Tribolium castaneum. Here, we report on the role of the pburs homodimer in signaling innate immunity in T. castaneum larvae. Through transcriptome analysis we identified a set of immune-related genes that respond to pburs RNAi. Treating larvae with recombinant-pburs protein led to up-regulation of antimicrobial peptide (AMP) genes in vivo and in vitro. The upregulation of most AMP genes was dependent on the NF-κB transcription factor Relish. Most importantly, we identified a novel AMP, Tenecin 3-like peptide (Ten3LP), regulated by pburs via NF-κB transcription factor Dorsal-related immunity factor (Dif)/Dorsal2, but not Relish. We conducted Ten3LP RNAi, synthesized recombinant Ten3LP protein for microbial inhibition assays and functionally characterized Ten3LP as an AMP specific for fungi and Gram-positive bacteria. We demonstrate that expression of Ten3LP is activated by pburs via the Toll pathway. These findings identify new molecular targets for development of potential antibiotics for treating microbial infections and perhaps for RNAi based pest management technology.
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Affiliation(s)
- Jingjing Li
- Division of Plant Science and Technology, University of Missouri, Columbia, MO 65211, USA.
| | - Bo Lyu
- Division of Plant Science and Technology, University of Missouri, Columbia, MO 65211, USA.
| | - Jingxiu Bi
- Division of Plant Science and Technology, University of Missouri, Columbia, MO 65211, USA; Institution of Quality Standard and Testing Technology for Agro-product, Shandong Academy of Agricultural Science, Jinan, Shandong 250100, China.
| | - Ruiqi Shan
- Division of Plant Science and Technology, University of Missouri, Columbia, MO 65211, USA.
| | - David Stanley
- Division of Plant Science and Technology, University of Missouri, Columbia, MO 65211, USA; Biological Control of Insect Research Laboratory, United States Department of Agriculture-Agricultural Research Station (USDA/ARS), Columbia, MO 65203, USA.
| | - Qili Feng
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China.
| | - Qisheng Song
- Division of Plant Science and Technology, University of Missouri, Columbia, MO 65211, USA.
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Sanda NB, Hou Y. The Symbiotic Bacteria- Xenorhabdus nematophila All and Photorhabdus luminescens H06 Strongly Affected the Phenoloxidase Activation of Nipa Palm Hispid, Octodonta nipae (Coleoptera: Chrysomelidae) Larvae. Pathogens 2023; 12:pathogens12040506. [PMID: 37111392 PMCID: PMC10142170 DOI: 10.3390/pathogens12040506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 02/24/2023] [Accepted: 02/24/2023] [Indexed: 04/29/2023] Open
Abstract
Symbiotic bacteria form a mutualistic relationship with nematodes and are pathogenic to many insect pests. They kill insects using various strategies to evade or suppress their humoral and cellular immunity. Here we evaluate the toxic effects of these bacteria and their secondary metabolites on the survival and phenoloxidase (PO) activation of Octodonta nipae larvae using biochemical and molecular methods. The results show P. luminescens H06 and X. nematophila All treatments caused significant reductions in the number of O. nipae larvae in a dose-dependent manner. Secondly, the O. nipae immune system recognizes symbiotic bacteria at early and late stages of infection via the induction of C-type lectin. Live symbiotic bacteria significantly inhibit PO activity in O. nipae whereas heat-treated bacteria strongly increase PO activity. Additionally, expression levels of four O. nipae proPhenoloxidase genes following treatment with P. luminescens H06 and X. nematophila All were compared. We found that the expression levels of all proPhenoloxidase genes were significantly down-regulated at all-time points. Similarly, treatments of O. nipae larvae with metabolites benzylideneacetone and oxindole significantly down-regulated the expression of the PPO gene and inhibited PO activity. However, the addition of arachidonic acid to metabolite-treated larvae restored the expression level of the PPO gene and increased PO activity. Our results provide new insight into the roles of symbiotic bacteria in countering the insect phenoloxidase activation system.
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Affiliation(s)
- Nafiu Bala Sanda
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Department of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Department of Crop Protection, Faculty of Agriculture, Bayero University Kano, Gwarzo Road, Kano 3011, Nigeria
| | - Youming Hou
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Department of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
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Hrithik MTH, Ahmed S, Kim Y. Damage signal induced by Bacillus thuringiensis infection triggers immune responses via a DAMP molecule in lepidopteran insect, Spodoptera exigua. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2023; 139:104559. [PMID: 36181778 DOI: 10.1016/j.dci.2022.104559] [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: 09/05/2022] [Revised: 09/23/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
Insect immunity defends the infection of an insect pathogenic bacterium, Bacillus thuringiensis (Bt). However, it was not clear on the recognition of Bt infection by the insect immune system. This study tested a physiological function of dorsal switch protein 1 (DSP1) in the Bt infection. DSP1 is classified into HMGB1-like damage-associated molecular pattern (DAMP) in insects. Upon Bt infection in a lepidopteran Spodoptera exigua, DSP1 was released from the nuclei of the midgut epithelium and activated immune responses. For this DSP1 release, a functional binding between Bt and its receptors on the midgut epithelium was required because any RNA interference (RNAi) treatments of Bt receptor (cadherin or ABCC) prevented the DSP1 release and became susceptible to the bacterial infection. The DSP1 release was required for the gene induction of Repat33, which is a member of response to pathogen gene family and its gene product mediated cellular and humoral immune responses against pathogen infection in S. exigua. The released DSP1 activated phospholipase A2 (PLA2) to produce eicosanoids, which induced the Repat33 expression because a hemocoelic injection of a recombinant DSP1 induced the Repat33 expression without Bt infection. However, any inhibition of PLA2 activity impaired the DAMP signaling between DSP1 and Repat33. DSP1 also up-regulated two other immune mediators, nitric oxide (NO) and a cytokine called plasmatocyte-spreading peptide (PSP). Either NO or PSP activated PLA2 to up-regulate Repat33 expression. These results suggest that Bt infection of the insect midgut generates a DAMP signal via DSP1 release, which turns on NO or the cytokine-PLA2-Repat33 immune signaling pathway.
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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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Roy MC, Ahmed S, Kim Y. Dorsal switch protein 1 as a damage signal in insect gut immunity to activate dual oxidase via an eicosanoid, PGE 2. Front Immunol 2022; 13:994626. [PMID: 36439105 PMCID: PMC9691268 DOI: 10.3389/fimmu.2022.994626] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 10/18/2022] [Indexed: 08/05/2023] Open
Abstract
Various microbiota including beneficial symbionts reside in the insect gut. Infections of pathogens cause dysregulation of the microflora and threaten insect survival. Reactive oxygen species (ROS) have been used in the gut immune responses, in which its production is tightly regulated by controlling dual oxidase (Duox) activity via Ca2+ signal to protect beneficial microflora and gut epithelium due to its high cytotoxicity. However, it was not clear how the insects discriminate the pathogens from the various microbes in the gut lumen to trigger ROS production. An entomopathogenic nematode (Steinernema feltiae) infection elevated ROS level in the gut lumen of a lepidopteran insect, Spodoptera exigua. Dorsal switch protein 1 (DSP1) localized in the nucleus in the midgut epithelium was released into plasma upon the nematode infection and activated phospholipase A2 (PLA2). The activated PLA2 led to an increase of PGE2 level in the midgut epithelium, in which rising Ca2+ signal up-regulated ROS production. Inhibiting DSP1 release by its specific RNA interference (RNAi) or specific inhibitor, 3-ethoxy-4-methoxyphenol, treatment failed to increase the intracellular Ca2+ level and subsequently prevented ROS production upon the nematode infection. A specific PLA2 inhibitor treatment also prevented the up-regulation of Ca2+ and subsequent ROS production upon the nematode infection. However, the addition of PGE2 to the inhibitor treatment rescued the gut immunity. DSP1 release was not observed at infection with non-pathogenic pathogens but detected in plasma with pathogenic infections that would lead to damage to the gut epithelium. These results indicate that DSP1 acts as a damage-associated molecular pattern in gut immunity through DSP1/PLA2/Ca2+/Duox.
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Choi B, Park WR, Kim YJ, Mun S, Park SJ, Jeong JH, Choi HS, Kim DK. Nuclear receptor estrogen-related receptor modulates antimicrobial peptide expression for host innate immunity in Tribolium castaneum. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2022; 148:103816. [PMID: 35926689 DOI: 10.1016/j.ibmb.2022.103816] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 07/15/2022] [Accepted: 07/26/2022] [Indexed: 06/15/2023]
Abstract
Antimicrobial peptides (AMPs) are core components of innate immunity to protect insects against microbial infections. Nuclear receptors (NRs) are ligand-dependent transcription factors that can regulate the expression of genes critical for insect development including molting and metamorphosis. However, the role of NRs in host innate immune response to microbial infection remains poorly understood in Tribolium castaneum (T. castaneum). Here, we show that estrogen-related receptor (ERR), an insect ortholog of the mammalian ERR family of NRs, is a novel transcriptional regulator of AMP genes for innate immune response of T. castaneum. Tribolium ERR (TcERR) expression was induced by immune deficiency (IMD)-Relish signaling in response to infection by Escherichia coli (E. coli), a Gram-negative bacterium, as demonstrated in TcIMD-deficient beetles. Interestingly, genome-wide transcriptome analysis of TcERR-deficient old larvae using RNA-sequencing analysis showed that TcERR expression was positively correlated with gene transcription levels of AMPs including attacins, defensins, and coleoptericin. Moreover, chromatin immunoprecipitation analysis revealed that TcERR could directly bind to ERR-response elements on promoters of genes encoding defensin3 and coleoptericin, critical for innate immune response of T. castaneum. Finally, TcERR-deficient old larvae infected with E. coli displayed enhanced bacterial load and significantly less host survival. These findings suggest that TcERR can coordinate transcriptional regulation of AMPs and host innate immune response to bacterial infection.
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Affiliation(s)
- Byungyoon Choi
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Republic of Korea.
| | - Woo-Ram Park
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Republic of Korea.
| | - Yu-Ji Kim
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Republic of Korea.
| | - Seulgi Mun
- Department of Applied Biology, Chonnam National University, Gwangju, 61186, Republic of Korea.
| | - Su-Jin Park
- Functional Biomaterial Research Center, Korea Research Institute of Bioscience and Biotechnology, Jeongeup, 56212, Republic of Korea.
| | - Jae-Ho Jeong
- Department of Microbiology, Chonnam National University Medical School, Gwangju, 61468, Republic of Korea.
| | - Hueng-Sik Choi
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, 61186, Republic of Korea.
| | - Don-Kyu Kim
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Republic of Korea.
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Patnaik BB, Lee YS, Han YS, Jo YH. Editorial: Innate Immune System Guiding Physiological Plasticity in Invertebrates. Front Physiol 2022; 13:947707. [PMID: 35774282 PMCID: PMC9237642 DOI: 10.3389/fphys.2022.947707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 05/23/2022] [Indexed: 11/15/2022] Open
Affiliation(s)
- Bharat Bhusan Patnaik
- Department of Biosciences and Biotechnology, Fakir Mohan University, Balasore, India
- Department of Biology, College of Natural Sciences, Soonchunhyang University, Asan, South Korea
- *Correspondence: Bharat Bhusan Patnaik,
| | - Yong Seok Lee
- Department of Biology, College of Natural Sciences, Soonchunhyang University, Asan, South Korea
| | - Yeon Soo Han
- Department of Applied Biology, Institute of Environmentally-Friendly Agriculture, College of Agriculture and Life Sciences, Chonnam National University, Gwangju, South Korea
| | - Yong Hun Jo
- Department of Applied Biology, Institute of Environmentally-Friendly Agriculture, College of Agriculture and Life Sciences, Chonnam National University, Gwangju, South Korea
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Wrońska AK, Kaczmarek A, Kazek M, Boguś MI. Infection of Galleria mellonella (Lepidoptera) Larvae With the Entomopathogenic Fungus Conidiobolus coronatus (Entomophthorales) Induces Apoptosis of Hemocytes and Affects the Concentration of Eicosanoids in the Hemolymph. Front Physiol 2022; 12:774086. [PMID: 35069239 PMCID: PMC8769874 DOI: 10.3389/fphys.2021.774086] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 11/03/2021] [Indexed: 01/11/2023] Open
Abstract
Apoptosis and autophagy, the mechanisms of programmed cell death, play critical roles in physiological and pathological processes in both vertebrates and invertebrates. Apoptosis is also known to play an important role in the immune response, particularly in the context of entomopathogenic infection. Of the factors influencing the apoptotic process during infection, two of the lesser known groups are caspases and eicosanoids. The aim of this study was to determine whether infection by the entomopathogenic soil fungus Conidiobolus coronatus is associated with apoptosis and changes in caspase activity in the hemocytes of Galleria mellonella larvae, and to confirm whether fungal infection may affect eicosanoid levels in the host. Larvae were exposed for 24 h to fully grown and sporulating fungus. Hemolymph was collected either immediately after termination of exposure (F24 group) or 24 h later (F48 group). Apoptosis/necrosis tests were performed in hemocytes using fluorescence microscopy and flow cytometry, while ELISA tests were used to measure eicosanoid levels. Apoptosis and necrosis occurred to the same degree in F24, but necrosis predominated in F48. Fungal infection resulted in caspase activation, increased PGE1, PGE2, PGA1, PGF2α, and 8-iso-PGF2α levels and decreased TXB2 levels, but had no effect on TXA2 or 11-dehydro-TXB2 concentrations. In addition, infected larvae demonstrated significantly increased PLA2 activity, known to be involved in eicosanoid biosynthesis. Our findings indicate that fungal infection simultaneously induces apoptosis in insects and stimulates general caspase activity, and this may be correlated with changes in the concentrations of eicosanoids.
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Affiliation(s)
| | - Agata Kaczmarek
- Witold Stefański Institute of Parasitology, Polish Academy of Sciences, Warsaw, Poland
| | - Michalina Kazek
- Witold Stefański Institute of Parasitology, Polish Academy of Sciences, Warsaw, Poland
| | - Mieczysława Irena Boguś
- Witold Stefański Institute of Parasitology, Polish Academy of Sciences, Warsaw, Poland.,BIOMIBO, Warsaw, Poland
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12
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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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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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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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Ray R, Potts R, Pietri JE. The Persistence of Escherichia coli Infection in German Cockroaches (Blattodea: Blattellidae) Varies Between Host Developmental Stages and is Influenced by the Gut Microbiota. JOURNAL OF MEDICAL ENTOMOLOGY 2020; 57:1964-1971. [PMID: 32516418 DOI: 10.1093/jme/tjaa108] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Indexed: 06/11/2023]
Abstract
The German cockroach, Blatella germanica (L.), is a suspected vector of several enteric bacterial pathogens, including Escherichia coli, among livestock and humans. However, little is known about the factors that influence bacterial transmission by cockroaches. Here, we orally infected B. germanica with various laboratory and field strains of E. coli and examined bacterial titers over time to shed new light on the factors that influence the dynamics of infection. Our results reveal that a laboratory strain of E. coli is largely cleared within 48 h while one field isolate can persist in a majority of cockroaches (80-100%) for longer than 3 d with minimal impact on cockroach longevity. We also find that the ability to clear some strains of E. coli is greater in cockroach nymphs than adults. Notably, no differential expression of the antimicrobial gene lysozyme was observed between nymphs and adults or in infected groups. However, clearance of E. coli was significantly reduced in gnotobiotic cockroaches that were reared in the absence of environmental bacteria, suggesting a protective role for the microbiota against exogenous bacterial pathogens. Together, these results demonstrate that the interactions between cockroaches and enteric bacterial pathogens are highly dynamic and influenced by a combination of microbial, host, and environmental parameters. Such factors may affect the disease transmission capacity of cockroaches in nature and should be further considered in both lab and field studies.
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Affiliation(s)
- Ritesh Ray
- Division of Basic Biomedical Sciences, University of South Dakota, Sanford School of Medicine, Vermillion, SD
| | - Rashaun Potts
- Division of Basic Biomedical Sciences, University of South Dakota, Sanford School of Medicine, Vermillion, SD
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Yan M, Wang W, Huang X, Wang X, Wang Y. Interactive effects of dietary cholesterol and phospholipids on the growth performance, expression of immune-related genes and resistance against Vibrio alginolyticus in white shrimp (Litopenaeus vannamei). FISH & SHELLFISH IMMUNOLOGY 2020; 97:100-107. [PMID: 31756453 DOI: 10.1016/j.fsi.2019.11.048] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 11/15/2019] [Accepted: 11/18/2019] [Indexed: 06/10/2023]
Abstract
A 56-day feeding trial was done to investigate the interactive effects of cholesterol (CHO) and phospholipids (PL) on the growth performance, immune response, expression of immune-related genes, and resistance against Vibrio alginolyticus of freshwater cultured white shrimp (Litopenaeus vannamei). A 3 × 3 experimental design was conducted with nine experimental diets containing three levels of CHO (0, 0.2%, and 0.4%) and three levels of PL (0, 2%, and 4%). The results indicated that the growth performance significantly (P < 0.05) increased with the increase in dietary CHO levels. Interactive effects between dietary CHO and PL on the growth parameters were not observed. Superoxide dismutase (SOD) and lysozyme activities were also significantly affected by dietary CHO levels. Furthermore, the interaction between these two additives was only detected in SOD activity. Shrimp fed experimental diet with CHO and PL supplementation showed better tolerance against Vibrio alginolyticus compared to the control, interactive effects (P < 0.05) were also detected on these two factors. The expression of immune deficiency (IMD) and lysozyme mRNA was up-regulated in shrimp fed diets with CHO and PL. The expression level of Toll-like receptor mRNA directly reflected the dietary CHO levels, which was not affected by dietary PL. The interaction between dietary CHO and PL was shown as the significant factor (P < 0.05) both in the expression of IMD and lysozyme mRNA, which indicated that different dietary levels of CHO and PL could strongly affect expression levels of some immune-relevant genes of the juvenile freshwater cultured L. vannamei.
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Affiliation(s)
- Minglei Yan
- Centre for Research on Environmental Ecology and Fish Nutrition (CREEFN) of the Ministry of Agriculture, Shanghai Ocean University, Shanghai, China
| | - Weilong Wang
- Centre for Research on Environmental Ecology and Fish Nutrition (CREEFN) of the Ministry of Agriculture, Shanghai Ocean University, Shanghai, China; Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Lingang New City, Shanghai, China
| | - Xuxiong Huang
- Centre for Research on Environmental Ecology and Fish Nutrition (CREEFN) of the Ministry of Agriculture, Shanghai Ocean University, Shanghai, China; Shanghai Engineering Research Center of Aquaculture, Shanghai, China; Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Lingang New City, Shanghai, China.
| | - Xinlei Wang
- Centre for Research on Environmental Ecology and Fish Nutrition (CREEFN) of the Ministry of Agriculture, Shanghai Ocean University, Shanghai, China
| | - Yi Wang
- Centre for Research on Environmental Ecology and Fish Nutrition (CREEFN) of the Ministry of Agriculture, Shanghai Ocean University, Shanghai, China
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17
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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, Vatanparast M, Stanley D, Kim Y. Secretion of secretory phospholipase A 2 into Spodoptera exigua larval midgut lumen and its role in lipid digestion. INSECT MOLECULAR BIOLOGY 2019; 28:773-784. [PMID: 30980443 DOI: 10.1111/imb.12588] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In insects, lipid digestion is controversial because insects have no bile salts to solubilize dietary lipids. One hypothesis is that a secretory type of phospholipase A2 (sPLA2 ) provides lysophospholipid (LPL) from dietary phospholipids (PLs). We identified a sPLA2 , Se-sPLA2 , in beet armyworm, Spodoptera exigua, that hydrolyses PLs at sn-2. Our goal was to investigate its role in lipid digestion. Se-sPLA2 was expressed in the entire alimentary canal. Incubating the isolated midgut in a cell culture medium led to secretion of Se-sPLA2 and other proteins. Ex vivo RNA interference (RNAi) of Se-sPLA2 expression in isolated midgut culture led to significantly decreased Se-sPLA2 secretion into the medium. Feeding double-stranded RNA specific to Se-sPLA2 to larvae suppressed sPLA2 activity in gut contents. A recombinant Se-sPLA2 was susceptible to benzylideneacetone (BZA), a specific PLA2 inhibitor. After feeding BZA to larvae, we recorded significant decreases in gut content sPLA2 activity, body growth and total haemolymph lipid contents. RNAi against Se-sPLA2 resulted in reduced digestibility. Addition of a specific LPL, 1-palmitoyl-sn-glycero-3-phosphocholine, to BZA-treated larvae rescued digestibility and larval growth. These results strongly bolster our hypothesis that Se-sPLA2 secreted from the midgut acts in lipid digestion by providing necessary LPL to solubilize dietary neutral lipids.
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Affiliation(s)
- S M Sajjadian
- Department of Plant Medicals, Andong National University, Andong, Korea
| | - M Vatanparast
- Department of Plant Medicals, Andong National University, Andong, Korea
| | - D Stanley
- Biological Control of Insect Research Laboratory, USDA/Agricultural Research Service, Beltsville, MD, USA
| | - Y Kim
- Department of Plant Medicals, Andong National University, Andong, Korea
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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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Regulation of the expression of nine antimicrobial peptide genes by TmIMD confers resistance against Gram-negative bacteria. Sci Rep 2019; 9:10138. [PMID: 31300668 PMCID: PMC6626034 DOI: 10.1038/s41598-019-46222-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 05/31/2019] [Indexed: 12/23/2022] Open
Abstract
Immune deficiency (IMD) is a death domain-containing protein that is essential for the IMD/NF-κB humoral and epithelial immune responses to Gram-negative bacteria and viruses in insects. In the immune signaling cascade, IMD is recruited together with FADD and the caspase DREDD after the mobilization of PGRP receptors. Activated IMD regulates the expression of effector antimicrobial peptides (AMP) that protect against invading microorganisms. To date, most studies of the IMD pathway, and the IMD gene in particular, have been restricted to Drosophila; few similar studies have been conducted in other model insects. Herein, we cloned and functionally characterized an IMD homolog from the mealworm beetle Tenebrio molitor (TmIMD) and studied its role in host survival in the context of pathogenic infections. Phylogenetic analysis revealed the conserved caspase cleavage site and inhibitor of apoptosis (IAP)-binding motif (IBM). TmIMD expression was high in the hemocytes and Malpighian tubules of Tenebrio late-instar larvae and adults. At 3 and 6 hours’ post-infection with Escherichia coli, Staphylococcus aureus, or Candida albicans, TmIMD expression significantly increased compared with mock-infected controls. Knockdown of the TmIMD transcript by RNAi significantly reduced host resistance to the Gram-negative bacterium E. coli and fungus C. albicans in a survival assay. Strikingly, the expression of nine T. molitor AMPs (TmTenecin1, TmTenecin2, TmTenecin4, TmDefensin2, TmColeoptericin1, TmColeoptericin2, TmAttacin1a, TmAttacin1b, and TmAttacin2) showed significant downregulation in TmIMD knockdown larvae challenged with E. coli. These results suggest that TmIMD is required to confer humoral immunity against the Gram-negative bacteria, E. coli by inducing the expression of critical transcripts that encode AMPs.
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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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Vatanparast M, Ahmed S, Herrero S, Kim Y. A non-venomous sPLA 2 of a lepidopteran insect: Its physiological functions in development and immunity. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 89:83-92. [PMID: 30107251 DOI: 10.1016/j.dci.2018.08.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 08/08/2018] [Accepted: 08/10/2018] [Indexed: 06/08/2023]
Abstract
Eicosanoids are oxygenated C20 polyunsaturated fatty acids that mediate various physiological processes in insects. Eicosanoid biosynthesis begins with a C20 precursor, arachidonic acid (5,8,11,14-eicosatetraenoic acid: AA). AA is usually released from phospholipids at sn-2 position by catalytic activity of phospholipase A2 (PLA2). Although various PLA2s classified into 16 gene families (= Groups) are known in various biological systems, few PLA2s are known in insects. Only two PLA2s involved in intracellular calcium independent PLA2 (iPLA2) group have been identified in lepidopteran insects with well known eicosanoid physiology. This study reports the first secretory PLA2 (sPLA2) in lepidopteran insects. A partial open reading frame (ORF) of PLA2 was obtained by interrogating Spodoptera exigua transcriptome. Subsequent 3'-RACE resulted in a full ORF (Se-sPLA2A) encoding 194 amino acid sequence containing signal peptide, calcium-binding domain, and catalytic site. Phylogenetic analysis indicated that Se-sPLA2A was clustered with other Group III sPLA2s. Se-sPLA2A was expressed in most larval instars except late last instar. Its expression was inducible by immune challenge and juvenile hormone analog injection. RNA interference of Se-sPLA2A significantly suppressed cellular immunity and impaired larval development. These results suggest that non-venomous sPLA2 plays a crucial role in immune and developmental processes in S. exigua, a lepidopteran insect.
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Affiliation(s)
- Mohammad Vatanparast
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea
| | - Shabbir Ahmed
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea
| | - Salvador Herrero
- Department of Genetics, Universitat de València, Dr Moliner 50, 46100, Burjassot, Valencia, Spain
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea.
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Kim Y, Ahmed S, Stanley D, An C. Eicosanoid-mediated immunity in insects. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 83:130-143. [PMID: 29225005 DOI: 10.1016/j.dci.2017.12.005] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 12/02/2017] [Accepted: 12/07/2017] [Indexed: 06/07/2023]
Abstract
Eicosanoid is a collective term for oxygenated metabolites of C20 polyunsaturated fatty acids. As seen in mammals, eicosanoids play crucial roles in mediating various physiological processes, including immune responses, in insects. Upon microbial pathogen infection, non-self recognition signals are propagated to nearly immune effectors such as hemocytes and fat body using various immune mediators, in which eicosanoid signals act as the ultimate downstream mediator. The chemical diversity of eicosanoids may operate to mediate various immune responses. Some entomopathogenic bacteria suppress eicosanoid biosynthesis, which inhibits host insect immunity and promotes their pathogenicity. This review introduces immune responses mediated by various eicosanoids. Then it explains the cross-talks of eicosanoids with other immune mediators including cytokines, biogenic monoamines, and nitric oxide to clarify the complexity of insect immune mediation. Finally, we highlight the biological significance of eicosanoids by demonstrating bacterial pathogenicity inhibiting a key enzyme - phospholipase A2 - in eicosanoid biosynthesis using their secondary metabolites to defend host insect immune attack.
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Affiliation(s)
- Yonggyun Kim
- Department of Plant Medicals, College of Natural Sciences, Andong National University, Andong 36729, Republic of Korea.
| | - Shabbir Ahmed
- Department of Plant Medicals, College of Natural Sciences, Andong National University, Andong 36729, Republic of Korea
| | - David Stanley
- USDA- ARS, Biological Control of Insects Research Laboratory, 1503 S. Providence Road, Columbia MO 65203, USA
| | - Chunju An
- Department of Entomology, China Agricultural University, Beijing 100193, China
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Sadekuzzaman M, Kim Y. Nitric oxide mediates antimicrobial peptide gene expression by activating eicosanoid signaling. PLoS One 2018; 13:e0193282. [PMID: 29466449 PMCID: PMC5821394 DOI: 10.1371/journal.pone.0193282] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 02/07/2018] [Indexed: 12/12/2022] Open
Abstract
Nitric oxide (NO) mediates both cellular and humoral immune responses in insects. Its mediation of cellular immune responses uses eicosanoids as a downstream signal. However, the cross-talk with two immune mediators was not known in humoral immune responses. This study focuses on cross-talk between two immune mediators in inducing gene expression of anti-microbial peptides (AMPs) of a lepidopteran insect, Spodoptera exigua. Up-regulation of eight AMPs was observed in S. exigua against bacterial challenge. However, the AMP induction was suppressed by injection of an NO synthase inhibitor, L-NAME, while little expressional change was observed on injecting its enantiomer, D-NAME. The functional association between NO biosynthesis and AMP gene expression was further supported by RNA interference (RNAi) against NO synthase (SeNOS), which suppressed AMP gene expression under the immune challenge. The AMP induction was also mimicked by NO alone because injecting an NO analog, SNAP, without bacterial challenge significantly induced the AMP gene expression. Interestingly, an eicosanoid biosynthesis inhibitor, dexamethasone (DEX), suppressed the NO induction of AMP expression. The inhibitory activity of DEX was reversed by the addition of arachidonic acid, a precursor of eicosanoid biosynthesis. AMP expression of S. exigua was also controlled by the Toll/IMD signal pathway. The RNAi of Toll receptors or Relish suppressed AMP gene expression by suppressing NO levels and subsequently reducing PLA2 enzyme activity. These results suggest that eicosanoids are a downstream signal of NO mediation of AMP expression against bacterial challenge.
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Affiliation(s)
- Md. Sadekuzzaman
- Department of Plant Medicals, Andong National University, Andong, Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, Korea
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Greenwood JM, Milutinović B, Peuß R, Behrens S, Esser D, Rosenstiel P, Schulenburg H, Kurtz J. Oral immune priming with Bacillus thuringiensis induces a shift in the gene expression of Tribolium castaneum larvae. BMC Genomics 2017; 18:329. [PMID: 28446171 PMCID: PMC5405463 DOI: 10.1186/s12864-017-3705-7] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Accepted: 04/12/2017] [Indexed: 12/22/2022] Open
Abstract
Background The phenomenon of immune priming, i.e. enhanced protection following a secondary exposure to a pathogen, has now been demonstrated in a wide range of invertebrate species. Despite accumulating phenotypic evidence, knowledge of its mechanistic underpinnings is currently very limited. Here we used the system of the red flour beetle, Tribolium castaneum and the insect pathogen Bacillus thuringiensis (Bt) to further our molecular understanding of the oral immune priming phenomenon. We addressed how ingestion of bacterial cues (derived from spore supernatants) of an orally pathogenic and non-pathogenic Bt strain affects gene expression upon later challenge exposure, using a whole-transcriptome sequencing approach. Results Whereas gene expression of individuals primed with the orally non-pathogenic strain showed minor changes to controls, we found that priming with the pathogenic strain induced regulation of a large set of distinct genes, many of which are known immune candidates. Intriguingly, the immune repertoire activated upon priming and subsequent challenge qualitatively differed from the one mounted upon infection with Bt without previous priming. Moreover, a large subset of priming-specific genes showed an inverse regulation compared to their regulation upon challenge only. Conclusions Our data demonstrate that gene expression upon infection is strongly affected by previous immune priming. We hypothesise that this shift in gene expression indicates activation of a more targeted and efficient response towards a previously encountered pathogen, in anticipation of potential secondary encounter. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3705-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jenny M Greenwood
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstrasse 1, 48149, Münster, Germany
| | - Barbara Milutinović
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstrasse 1, 48149, Münster, Germany.,Institute of Science and Technology Austria, Am Campus 1, 3400, Klosterneuburg, Austria
| | - Robert Peuß
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstrasse 1, 48149, Münster, Germany.,Current Address: Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO, 64110, USA
| | - Sarah Behrens
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstrasse 1, 48149, Münster, Germany
| | - Daniela Esser
- Institute of Clinical Molecular Biology, Christian-Albrechts University Kiel, Schittenhelmstr. 12, 24105, Kiel, Germany
| | - Philip Rosenstiel
- Institute of Clinical Molecular Biology, Christian-Albrechts University Kiel, Schittenhelmstr. 12, 24105, Kiel, Germany
| | - Hinrich Schulenburg
- Zoological Institute, Christian-Albrechts University Kiel, Am Botanischen Garten 1-9, 24118, Kiel, Germany
| | - Joachim Kurtz
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstrasse 1, 48149, Münster, Germany.
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Tate AT, Andolfatto P, Demuth JP, Graham AL. The within-host dynamics of infection in trans-generationally primed flour beetles. Mol Ecol 2017; 26:3794-3807. [PMID: 28277618 DOI: 10.1111/mec.14088] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 02/17/2017] [Accepted: 02/21/2017] [Indexed: 12/19/2022]
Abstract
Many taxa exhibit plastic immune responses initiated after primary microbial exposure that provide increased protection against disease-induced mortality and the fitness costs of infection. In several arthropod species, this protection can even be passed from parents to offspring through a phenomenon called trans-generational immune priming. Here, we first demonstrate that trans-generational priming is a repeatable phenomenon in flour beetles (Tribolium castaneum) primed and infected with Bacillus thuringiensis (Bt). We then quantify the within-host dynamics of microbes and host physiological responses in infected offspring from primed and unprimed mothers by monitoring bacterial density and using mRNA-seq to profile host gene expression, respectively, over the acute infection period. We find that priming increases inducible resistance against Bt around a critical temporal juncture where host septicaemic trajectories, and consequently survival, may be determined in unprimed individuals. Our results identify a highly differentially expressed biomarker of priming, containing an EIF4-e domain, in uninfected individuals, as well as several other candidate genes. Moreover, the induction and decay dynamics of gene expression over time suggest a metabolic shift in primed individuals. The identified bacterial and gene expression dynamics are likely to influence patterns of bacterial fitness and disease transmission in natural populations.
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Affiliation(s)
- Ann T Tate
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA
| | - Peter Andolfatto
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA
| | - Jeffery P Demuth
- Department of Biology, University of Texas, Arlington, TX, 76010, USA
| | - Andrea L Graham
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA
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Sadekuzzaman M, Park Y, Lee S, Kim K, Jung JK, Kim Y. An entomopathogenic bacterium, Xenorhabdus hominickii ANU101, produces oxindole and suppresses host insect immune response by inhibiting eicosanoid biosynthesis. J Invertebr Pathol 2017; 145:13-22. [PMID: 28302381 DOI: 10.1016/j.jip.2017.03.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 03/06/2017] [Accepted: 03/10/2017] [Indexed: 11/16/2022]
Abstract
An entomopathogenic bacterium, Xenorhabdus hominickii ANU101, was isolated from an entomopathogenic nematode, Steinernema monticolum. X. hominickii exhibited significant insecticidal activities at ≥6.6×102 colony-forming units per larva against a lepidopteran insect, Spodoptera exigua with hemocoelic injection. The insecticidal activity of X. hominickii was reduced by an addition of arachidonic acid (AA, a catalytic product of PLA2), but enhanced by an addition by dexamethasone (DEX, a specific inhibitor of PLA2). S. exigua could defend the bacterial infection by forming hemocyte nodules. However, live X. hominickii significantly reduced the hemocytic nodulation compared to similar treatment with heat-killed X. hominickii. An addition of AA to live X. hominickii significantly rescued the immunosuppression. X. hominickii also inhibited phenoloxidase activity in hemolymph of S. exigua larvae. Furthermore, the bacteria suppressed gene expressions of antimicrobial peptides, such as attacin-1, attacin-2, defensin, gallerimycin and transferrin-1 of S. exigua. An organic extract of X. hominickii-cultured broth with ethyl acetate possessed oxindole and significantly suppressed hemocyte nodulation. Again, an addition of AA diminished the inhibitory activity of the organic extract against hemocyte nodulation. Oxindole alone inhibited hemocyte nodulation and PLA2 enzyme activity. These results suggest that the entomopathogenicity of X. hominickii comes from its inhibitory activity against eicosanoid biosynthesis of target insects.
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Affiliation(s)
- Md Sadekuzzaman
- Department of Bioresource Sciences, Andong National University, Andong 36729, Republic of Korea
| | - Youngjin Park
- Department of Bioresource Sciences, Andong National University, Andong 36729, Republic of Korea
| | - Seunghee Lee
- Department of Bioresource Sciences, Andong National University, Andong 36729, Republic of Korea
| | - Kunwoo Kim
- Department of Bioresource Sciences, Andong National University, Andong 36729, Republic of Korea
| | - Jin Kyo Jung
- Division of Crop Cultivation and Environment Research, Department of Central Area Crop Science, National Institute of Crop Science, Rural Development Administration, Suwon 16429, Republic of Korea
| | - Yonggyun Kim
- Department of Bioresource Sciences, Andong National University, Andong 36729, Republic of Korea.
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Schlotz N, Roulin A, Ebert D, Martin-Creuzburg D. Combined effects of dietary polyunsaturated fatty acids and parasite exposure on eicosanoid-related gene expression in an invertebrate model. Comp Biochem Physiol A Mol Integr Physiol 2016; 201:115-123. [DOI: 10.1016/j.cbpa.2016.07.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 07/08/2016] [Accepted: 07/08/2016] [Indexed: 01/09/2023]
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Park Y, Stanley DW, Kim Y. Eicosanoids up-regulate production of reactive oxygen species by NADPH-dependent oxidase in Spodoptera exigua phagocytic hemocytes. JOURNAL OF INSECT PHYSIOLOGY 2015; 79:63-72. [PMID: 26071791 DOI: 10.1016/j.jinsphys.2015.06.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 05/15/2015] [Accepted: 06/09/2015] [Indexed: 06/04/2023]
Abstract
Eicosanoids mediate cellular immune responses in insects, including phagocytosis of invading microbes. Phagocytosis entails two major steps, the internalization of microbes and the subsequent killing of them via formation of reactive oxygen species (ROS). Here, we posed the hypothesis that eicosanoids mediate ROS production by activating NADPH-dependent oxidase (NOX) and tested the idea in the model insect, Spodoptera exigua. A NOX gene (we named SeNOX4) was identified and cloned, yielding a full open reading frame encoding 547 amino acid residues with a predicted molecular weight of 63,410Da and an isoelectric point at 9.28. A transmembrane domain and a large intracellular domain containing NADPH and FAD-binding sites were predicted. Phylogenetic analysis indicated SeNOX4 clusters with other NOX4 genes. SeNOX4 was expressed in all life stages except eggs, and exclusively in hemocytes. Bacterial challenge and, separately, arachidonic acid (AA, a precursor of eicosanoid biosynthesis) injection increased its expression. The internalization step was assessed by counting hemocytes engulfing fluorescence-labeled bacteria. The phagocytic behavior was inhibited by dsRNA suppression of SeNOX4 expression and, separately by dexamethasone (DEX, a specific inhibitor of eicosanoid biosynthesis) treatments. However, injecting AA to dsSeNOX4-treated larvae did not rescue the phagocytic activity. Hemocytic ROS production increased following bacterial challenge, which was sharply reduced in dsSeNOX4-treated, and separately, in DEX-treated larvae. AA partially reversed the suppressed ROS production in dsSeNOX4-treated larvae. Treating larvae with either the ROS-suppressing dsSeNOX4 construct or DEX rendered experimental larvae unable to inhibit bacterial proliferation in their hemocoels. We infer that eicosanoids mediate ROS production during phagocytosis by inducing expression of SeNOX4.
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Affiliation(s)
- Youngjin Park
- Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea
| | - David W Stanley
- Biological Control of Insects Research Laboratory, USDA/Agricultural Research Service, 1503 Providence Rd., Columbia, MO 65203, USA
| | - Yonggyun Kim
- Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea.
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Jacobs CGC, Spaink HP, van der Zee M. The extraembryonic serosa is a frontier epithelium providing the insect egg with a full-range innate immune response. eLife 2014; 3:e04111. [PMID: 25487990 PMCID: PMC4358341 DOI: 10.7554/elife.04111] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 11/10/2014] [Indexed: 01/23/2023] Open
Abstract
Drosophila larvae and adults possess a potent innate immune response, but the response of Drosophila eggs is poor. In contrast to Drosophila, eggs of the beetle Tribolium are protected by a serosa, an extraembryonic epithelium that is present in all insects except higher flies. In this study, we test a possible immune function of this frontier epithelium using Tc-zen1 RNAi-mediated deletion. First, we show that bacteria propagate twice as fast in serosa-less eggs. Then, we compare the complete transcriptomes of wild-type, control RNAi, and Tc-zen1 RNAi eggs before and after sterile or septic injury. Infection induces genes involved in Toll and IMD-signaling, melanisation, production of reactive oxygen species and antimicrobial peptides in wild-type eggs but not in serosa-less eggs. Finally, we demonstrate constitutive and induced immune gene expression in the serosal epithelium using in situ hybridization. We conclude that the serosa provides insect eggs with a full-range innate immune response.
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Affiliation(s)
| | - Herman P Spaink
- Institute of Biology, Leiden University, Leiden, Netherlands
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Hwang J, Park Y, Kim Y, Hwang J, Lee D. An entomopathogenic bacterium, Xenorhabdus nematophila, suppresses expression of antimicrobial peptides controlled by Toll and Imd pathways by blocking eicosanoid biosynthesis. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2013; 83:151-169. [PMID: 23740621 DOI: 10.1002/arch.21103] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Immune-associated genes of the beet armyworm, Spodoptera exigua, were predicted from 454 pyrosequencing transcripts of hemocytes collected from fifth instar larvae challenged with bacteria. Out of 22,551 contigs and singletons, 36% of the transcripts had at least one significant hit (E-value cutoff of 1e-20) and used to predict immune-associated genes implicated in pattern recognition, prophenoloxidase activation, intracellular signaling, and antimicrobial peptides (AMPs). Immune signaling and AMP genes were further confirmed in their expression patterns in response to different types of microbial challenge. To discriminate the AMP expression signaling between Toll and Imd pathways, RNA interference was applied to specifically knockdown each signal pathway; the separate silencing treatments resulted in differential suppression of AMP genes. An entomopathogenic bacterium, Xenorhabdus nematophila, suppressed expression of most AMP genes controlled by Toll and Imd pathways, while challenge with heat-killed X. nematophila induced expression of all AMPs in experimental larvae. Benzylideneacetone (BZA), a metabolite of X. nematophila, suppressed the AMP gene inductions when it was co-injected with the heat-killed X. nematophila. However, arachidonic acid, a catalytic product of PLA2 , significantly reversed the inhibitory effect of BZA on the AMP gene expression. This study suggests that X. nematophila suppresses AMP production controlled by Toll and Imd pathways by inhibiting eicosanoid biosynthesis in S. exigua.
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Affiliation(s)
- Jihyun Hwang
- Department of Bioresource Sciences, Andong National University, Andong, Korea
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Genard B, Miner P, Nicolas JL, Moraga D, Boudry P, Pernet F, Tremblay R. Integrative study of physiological changes associated with bacterial infection in Pacific oyster larvae. PLoS One 2013; 8:e64534. [PMID: 23704993 PMCID: PMC3660371 DOI: 10.1371/journal.pone.0064534] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 04/16/2013] [Indexed: 12/30/2022] Open
Abstract
Background Bacterial infections are common in bivalve larvae and can lead to significant mortality, notably in hatcheries. Numerous studies have identified the pathogenic bacteria involved in such mortalities, but physiological changes associated with pathogen exposure at larval stage are still poorly understood. In the present study, we used an integrative approach including physiological, enzymatic, biochemical, and molecular analyses to investigate changes in energy metabolism, lipid remodelling, cellular stress, and immune status of Crassostrea gigas larvae subjected to experimental infection with the pathogenic bacteria Vibrio coralliilyticus. Findings Our results showed that V. coralliilyticus exposure induced (1) limited but significant increase of larvae mortality compared with controls, (2) declined feeding activity, which resulted in energy status changes (i.e. reserve consumption, β-oxidation, decline of metabolic rate), (3) fatty acid remodeling of polar lipids (changes in phosphatidylinositol and lysophosphatidylcholine composition`, non-methylene–interrupted fatty acids accumulation, lower content of major C20 polyunsaturated fatty acids as well as activation of desaturases, phospholipase and lipoxygenase), (4) activation of antioxidant defenses (catalase, superoxide dismutase, peroxiredoxin) and cytoprotective processes (heat shock protein 70, pernin), and (5) activation of the immune response (non-self recognition, NF-κκ signaling pathway, haematopoiesis, eiconosoids and lysophosphatidyl acid synthesis, inhibitor of metalloproteinase and antimicrobial peptides). Conclusion Overall, our results allowed us to propose an integrative view of changes induced by a bacterial infection in Pacific oyster larvae, opening new perspectives on the response of marine bivalve larvae to infections.
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Affiliation(s)
- Bertrand Genard
- Institut des sciences de la mer, Université du Québec à Rimouski, Rimouski, Québec, Canada.
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Park JA, Kim Y. Toll recognition signal activates oenocytoid cell lysis via a crosstalk between plasmatocyte-spreading peptide and eicosanoids in response to a fungal infection. Cell Immunol 2012; 279:117-23. [DOI: 10.1016/j.cellimm.2012.11.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 09/27/2012] [Accepted: 11/02/2012] [Indexed: 12/31/2022]
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Park JA, Kim Y. Phospholipase A2 inhibitors in bacterial culture broth enhance pathogenicity of a fungus Nomuraea rileyi. J Microbiol 2012; 50:644-51. [DOI: 10.1007/s12275-012-2108-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 04/25/2012] [Indexed: 12/29/2022]
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Park JA, Kim Y. Eicosanoid biosynthesis is activated via Toll, but not Imd signal pathway in response to fungal infection. J Invertebr Pathol 2012; 110:382-8. [DOI: 10.1016/j.jip.2012.04.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 03/27/2012] [Accepted: 04/28/2012] [Indexed: 11/17/2022]
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Yokoi K, Koyama H, Minakuchi C, Tanaka T, Miura K. Antimicrobial peptide gene induction, involvement of Toll and IMD pathways and defense against bacteria in the red flour beetle, Tribolium castaneum. RESULTS IN IMMUNOLOGY 2012; 2:72-82. [PMID: 24371569 DOI: 10.1016/j.rinim.2012.03.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 03/20/2012] [Accepted: 03/22/2012] [Indexed: 11/25/2022]
Abstract
Using Tribolium castaneum, we quantitatively investigated the induction of nine antimicrobial peptide (AMP) genes by live gram-negative bacteria (Escherichia coli and Enterobacter cloacae), gram-positive bacteria (Micrococcus luteus and Bacillus subtilis) and the budding yeast (Saccharomyces cerevisiae). Then, five representative AMP genes were selected, and the involvement of the Toll and IMD pathways in their induction by E. coli, M. luteus and S. cerevisiae was examined by utilizing RNA interference of either MyD88 or IMD. Results indicated: Robust and acute induction of three genes by the two bacterial species was mediated mainly by the IMD pathway; slow and sustained induction of one gene by the two bacteria was mediated mainly by the Toll pathway; induction of the remaining one gene by the two bacteria was mediated by both pathways; induction of the five genes by the yeast was mediated by the Toll and/or IMD pathways depending on respective genes. These results suggest that more promiscuous activation and usage of the two pathways may occur in T. castaneum than in Drosophila melanogaster. In addition, the IMD pathway was revealed to dominantly contribute to defense against two bacterial species, gram-negative E. cloacae and gram-positive B. subtilis that possesses DAP-type peptidoglycan.
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Key Words
- AMP, antimicrobial peptide
- Antimicrobial peptide
- Att1, Attacin1
- Att2, Attacin2
- Att3, Attacin3
- Bs, Bacillus subtilis
- Cec2, Cecropin2
- Cec3, Cecropin3
- Col1, Coleoptericin1
- Def1, Defensin1
- Def2, Defensin2
- Def3, Defensin3
- Ec, Escherichia coli
- Ecl, Enterobacter cloacae
- FADD, Fas-associated death domain containing protein
- GNBP, gram-negative binding protein
- IMD pathway
- Innate immunity
- Ml, Micrococcus luteus
- PAMP, pathogen-associated molecular pattern
- PG, peptidoglycan
- PGRP, peptidoglycan recognition protein
- PRR, pattern recognition receptor
- RNAi, RNA interference
- RPL32, ribosomal protein L32
- RT-PCR, reverse transcription-PCR
- Sc, Saccharomyces cerevisiae
- Toll pathway
- Tribolium castaneum
- dsRNA, double strand RNA
- malE, maltose binding protein E
- qRT-PCR, real-time quantitative RT-PCR
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Affiliation(s)
- Kakeru Yokoi
- Applied Entomology Laboratory, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan
| | - Hiroaki Koyama
- Applied Entomology Laboratory, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan
| | - Chieka Minakuchi
- Applied Entomology Laboratory, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan
| | - Toshiharu Tanaka
- Applied Entomology Laboratory, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan
| | - Ken Miura
- Applied Entomology Laboratory, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan
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Ntwasa M, Goto A, Kurata S. Coleopteran antimicrobial peptides: prospects for clinical applications. Int J Microbiol 2012; 2012:101989. [PMID: 22500175 PMCID: PMC3303552 DOI: 10.1155/2012/101989] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 11/02/2011] [Accepted: 12/05/2011] [Indexed: 12/20/2022] Open
Abstract
Antimicrobial peptides (AMPs) are activated in response to septic injury and have important roles in vertebrate and invertebrate immune systems. AMPs act directly against pathogens and have both wound healing and antitumor activities. Although coleopterans comprise the largest and most diverse order of eukaryotes and occupy an earlier branch than Drosophila in the holometabolous lineage of insects, their immune system has not been studied extensively. Initial research reports, however, indicate that coleopterans possess unique immune response mechanisms, and studies of these novel mechanisms may help to further elucidate innate immunity. Recently, the complete genome sequence of Tribolium was published, boosting research on coleopteran immunity and leading to the identification of Tribolium AMPs that are shared by Drosophila and mammals, as well as other AMPs that are unique. AMPs have potential applicability in the development of vaccines. Here, we review coleopteran AMPs, their potential impact on clinical medicine, and the molecular basis of immune defense.
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Affiliation(s)
- Monde Ntwasa
- School of Molecular and Cell Biology, University of the Witwatersrand, Wits 2050, South Africa
| | - Akira Goto
- Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba 6-3, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Shoichiro Kurata
- Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba 6-3, Aramaki, Aoba-ku, Sendai 980-8578, Japan
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Stanley D, Kim Y. Prostaglandins and their receptors in insect biology. Front Endocrinol (Lausanne) 2011; 2:105. [PMID: 22654840 PMCID: PMC3356066 DOI: 10.3389/fendo.2011.00105] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 12/05/2011] [Indexed: 12/13/2022] Open
Abstract
We treat the biological significance of prostaglandins (PGs) and their known receptors in insect biology. PGs and related eicosanoids are oxygenated derivatives of arachidonic acid (AA) and two other C20 polyunsaturated fatty acids. PGs are mostly appreciated in the context of biomedicine, but a growing body of literature indicates the biological significance of these compounds extends throughout the animal kingdom, and possibly beyond. The actions of most PGs are mediated by specific receptors. Biomedical research has discovered a great deal of knowledge about PG receptors in mammals, including their structures, pharmacology, molecular biology and cellular locations. Studies of PG receptors in insects lag behind the biomedical background, however, recent results hold the promise of accelerated research in this area. A PG receptor has been identified in a class of lepidopteran hemocytes and experimentally linked to the release of prophenoloxidase. PGs act in several crucial areas of insect biology. In reproduction, a specific PG, PGE(2), releases oviposition behavior in most crickets and a few other insect species; PGs also mediate events in egg development in some species, which may represent all insects. PGs play major roles in modulating fluid secretion in Malpighian tubules, rectum and salivary glands, although, again, this has been studied in only a few insect species that may represent the Class. Insect immunity is a very complex defense system. PGs and other eicosanoids mediate a large number of immune reactions to infection and invasion. We conclude that research into PGs and their receptors in insects will lead to important advances in our understanding of insect biology.
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Affiliation(s)
- David Stanley
- Biological Control of Insects Research Laboratory, Agricultural Research Service, United States Department of AgricultureColumbia, MO, USA
- *Correspondence: David Stanley, Biological Control of Insects Research Laboratory, Agricultural Research Service, United States Department of Agriculture, 1503 South Providence Road, Columbia, MO 65203, USA. e-mail:
| | - Yonggyun Kim
- Department of Bioresource Sciences, Andong National UniversityAndong, Republic of Korea
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Kim J, Kim Y. Benzylideneacetone, an eicosanoid biosynthesis inhibitor enhances baculovirus pathogenicity in the diamondback moth, Plutella xylostella. J Invertebr Pathol 2010; 106:308-13. [PMID: 21112333 DOI: 10.1016/j.jip.2010.11.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 11/13/2010] [Accepted: 11/19/2010] [Indexed: 01/22/2023]
Abstract
Benzylideneacetone (BZA) is a monoterpenoid compound produced by an entomopathogenic bacterium, Xenorhabdus nematophila. BZA inhibits phospholipase A(2) to suppress biosynthesis of eicosanoids that mediate immune responses in insects. In response to per os infection of Autographa californica multiple nucleopolyhedrosis virus (AcMNPV), the diamondback moth, Plutella xylostella, developed red spots on the midgut epithelium. The midgut exhibiting red spot formation suffered abnormal cell integrity, such as genomic DNA fragmentation and condensed spots in the nucleoplasm. The number of red spots increased with viral dose and incubation time after the viral treatment. BZA inhibited the formation of the midgut red spots in a dose-dependent manner. However, the inhibitory effect of BZA on the red spot formation was reversed by addition of arachidonic acid, suggesting that the red spot response may be mediated by eicosanoids. BZA treatment resulted in significant enhancement of AcMNPV occlusion body (OB) pathogenicity to P. xylostella.
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Affiliation(s)
- Jiwan Kim
- Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea
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