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Morejon B, Michel K. A zone-of-inhibition assay to screen for humoral antimicrobial activity in mosquito hemolymph. Front Cell Infect Microbiol 2023; 13:891577. [PMID: 36779191 PMCID: PMC9908765 DOI: 10.3389/fcimb.2023.891577] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 01/10/2023] [Indexed: 01/27/2023] Open
Abstract
In insects, antibacterial immunity largely depends on the activation of downstream signaling and effector responses, leading to the synthesis and secretion of soluble effector molecules, such as antimicrobial peptides (AMPs). AMPs are acute infection response peptides secreted into the hemolymph upon bacterial stimulation. The transcription of innate immunity genes encoding for AMPs is highly dependent on several signaling cascade pathways, such as the Toll pathway. In the African malaria mosquito, Anopheles gambiae, AMPs hold a special interest as their upregulation have been shown to limit the growth of malaria parasites, bacteria, and fungi. Most of the current knowledge on the regulation of insect AMPs in microbial infection have been obtained from Drosophila. However, largely due to the lack of convenient assays, the regulation of antimicrobial activity in mosquito hemolymph is still not completely understood. In this study, we report a zone of inhibition assay to identify the contribution of AMPs and components of the Toll pathway to the antimicrobial activity of A. gambiae hemolymph. As a proof of principle, we demonstrate that Micrococcus luteus challenge induces antimicrobial activity in the adult female mosquito hemolymph, which is largely dependent on defensin 1. Moreover, by using RNAi to silence Cactus, REL1, and MyD88, we showed that Cactus kd induces antimicrobial activity in the mosquito hemolymph, whereas the antimicrobial activity in REL1 kd and MyD88 kd is reduced after challenge. Finally, while injection itself is not sufficient to induce antimicrobial activity, our results show that it primes the response to bacterial challenge. Our study provides information that increases our knowledge of the regulation of antimicrobial activity in response to microbial infections in mosquitoes. Furthermore, this assay represents an ex vivo medium throughput assay that can be used to determine the upstream regulatory elements of antimicrobial activity in A. gambiae hemolymph.
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Affiliation(s)
- Bianca Morejon
- Division of Biology, Kansas State University, Manhattan, KS, United States
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2
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Niu Y, Zhao Y, Shi F, Li M, Zhang S, Yang J, Zong S, Tao J. An Efficient and Simple Method for Collecting Haemolymph of Cerambycidae (Insecta: Coleoptera) Adults. INSECTS 2022; 14:29. [PMID: 36661957 PMCID: PMC9863847 DOI: 10.3390/insects14010029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/23/2022] [Accepted: 12/23/2022] [Indexed: 06/17/2023]
Abstract
Cerambycid beetles (Cerambycidae) are major forest pests, posing a serious threat to the security of forest resources worldwide. Extensive research has focused on the control of cerambycid beetles from physiological and biochemical perspectives. Despite the important roles of insect haemolymph in physiological processes, efficient collection methods for Cerambycidae are lacking. For the efficient and easy collection of large amounts of pure haemolymph from adult cerambycid beetles, a new method, named net centrifugation, was developed. Three species of cerambycid beetles with large differences in size, Anoplophora chinensis, Monochamus saltuarius and Saperda populnea, were selected for the study. Haemolymph was collected by the newly developed net centrifugation method-in which an inner nylon net is used during centrifugation under optimised conditions, and a relatively small wound is generated on the insect-as well as the traditional tearing method and double centrifugation method. Among the three methods evaluated, the net centrifugation method caused the least damage to cerambycid beetles during the whole operation. This method resulted in the most haemolymph from a single beetle, with the lowest turbidity, mostly pure haemocytes in the precipitate, the clearest haemolymph smears by microscopy and the highest quality of RNA extracted from haemocytes. The net centrifugation method has a high collection efficiency, providing important technical support for haemolymph extraction and entomological research.
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Affiliation(s)
- Yiming Niu
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing 100083, China
| | - Yuxuan Zhao
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing 100083, China
| | - Fengming Shi
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing 100083, China
| | - Meng Li
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing 100083, China
| | - Sainan Zhang
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing 100083, China
| | - Jinglin Yang
- Mentougou Forestry Station, Beijing 102308, China
| | - Shixiang Zong
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing 100083, China
| | - Jing Tao
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing 100083, China
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3
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Antiviral RNAi Mechanisms to Arboviruses in Mosquitoes: microRNA Profile of Aedes aegypti and Culex quinquefasciatus from Grenada, West Indies. Appl Microbiol 2022. [DOI: 10.3390/applmicrobiol2020029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mosquito-borne arboviruses, such as dengue virus, West Nile virus, Zika virus and yellow fever virus, impose a tremendous cost on the health of populations around the world. As a result, much effort has gone into the study of the impact of these viruses on human infections. Comparatively less effort, however, has been made to study the way these viruses interact with mosquitoes themselves. As ingested arboviruses infect their midgut and subsequently other tissue, the mosquito mounts a multifaceted innate immune response. RNA interference, the central intracellular antiviral defense mechanism in mosquitoes and other invertebrates can be induced and modulated through outside triggers (small RNAs) and treatments (transgenesis or viral-vector delivery). Accordingly, modulation of this facet of the mosquito’s immune system would thereby suggest a practical strategy for vector control. However, this requires a detailed understanding of mosquitoes’ endogenous small RNAs and their effects on the mosquito and viral proliferation. This paper provides an up-to-date overview of the mosquito’s immune system along with novel data describing miRNA profiles for Aedes aegypti and Culex quinquefasiatus in Grenada, West Indies.
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Amaro IA, Ahmed-Braimah YH, League GP, Pitcher SA, Avila FW, Cruz PC, Harrington LC, Wolfner MF. Seminal fluid proteins induce transcriptome changes in the Aedes aegypti female lower reproductive tract. BMC Genomics 2021; 22:896. [PMID: 34906087 PMCID: PMC8672594 DOI: 10.1186/s12864-021-08201-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 11/23/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Mating induces behavioral and physiological changes in the arbovirus vector Aedes aegypti, including stimulation of egg development and oviposition, increased survival, and reluctance to re-mate with subsequent males. Transferred seminal fluid proteins and peptides derived from the male accessory glands induce these changes, though the mechanism by which they do this is not known. RESULTS To determine transcriptome changes induced by seminal proteins, we injected extract from male accessory glands and seminal vesicles (MAG extract) into females and examined female lower reproductive tract (LRT) transcriptomes 24 h later, relative to non-injected controls. MAG extract induced 87 transcript-level changes, 31 of which were also seen in a previous study of the LRT 24 h after a natural mating, including 15 genes with transcript-level changes similarly observed in the spermathecae of mated females. The differentially-regulated genes are involved in diverse molecular processes, including immunity, proteolysis, neuronal function, transcription control, or contain predicted small-molecule binding and transport domains. CONCLUSIONS Our results reveal that seminal fluid proteins, specifically, can induce gene expression responses after mating and identify gene targets to further investigate for roles in post-mating responses and potential use in vector control.
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Affiliation(s)
- I Alexandra Amaro
- Department of Entomology, Cornell University, Ithaca, NY, 14853, USA
| | | | - Garrett P League
- Department of Entomology, Cornell University, Ithaca, NY, 14853, USA
| | - Sylvie A Pitcher
- Department of Entomology, Cornell University, Ithaca, NY, 14853, USA
| | - Frank W Avila
- Max Planck Tandem Group in Mosquito Reproductive Biology, Universidad de Antioquia, Medellín, 050010, Colombia
| | - Priscilla C Cruz
- Department of Entomology, Cornell University, Ithaca, NY, 14853, USA
| | | | - Mariana F Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA.
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5
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Singh LR, Chen YL, Xie YY, Xia W, Gong XW, Hider RC, Zhou T. Functionality study of chalcone-hydroxypyridinone hybrids as tyrosinase inhibitors and influence on anti-tyrosinase activity. J Enzyme Inhib Med Chem 2021; 35:1562-1567. [PMID: 32746652 PMCID: PMC7470021 DOI: 10.1080/14756366.2020.1801669] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In an attempt to synthesise new tyrosinase inhibitors, we designed and synthesised a series of chalcone-hydroxypyridinone hybrids as potential tyrosinase inhibitors adopting strategic modifications of kojic acid. All the newly synthesised compounds were characterised by NMR and mass spectrometry. Initial screening of the target compounds demonstrated that compounds 1a, 1d, and 1n had relatively strong inhibitory activities against tyrosinase monophenolase, with IC50 values of 3.07 ± 0.85, 2.25 ± 0.8 and 2.75 ± 1.19 μM, respectively. The inhibitory activity against monophenolase was 6- to 8-fold higher than that of kojic acid. Compounds 1a, 1d, and 1n also showed inhibition of diphenolase, with IC50 values of 17.05 ± 0.07, 11.70 ± 0.03 and 19.3 ± 0.28 μM, respectively. The inhibition kinetics of diphenolase indicates that compounds 1a and 1d induce reversible inhibition on tyrosinase. Finally, we found that copper coordination should be one of the important inhibitory mechanism of these compounds in tyrosinase.
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Affiliation(s)
- L Ravithej Singh
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang, PR China
| | - Yu-Lin Chen
- Division of Pharmaceutical Science, King's College London, London, UK
| | - Yuan-Yuan Xie
- College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou, PR China
| | - Wei Xia
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang, PR China
| | - Xing-Wen Gong
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang, PR China
| | - Robert C Hider
- Division of Pharmaceutical Science, King's College London, London, UK
| | - Tao Zhou
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang, PR China
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6
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Estévez-Lao TY, Sigle LT, Gomez SN, Hillyer JF. Nitric oxide produced by periostial hemocytes modulates the bacterial infection-induced reduction of the mosquito heart rate. J Exp Biol 2020; 223:jeb225821. [PMID: 32561636 DOI: 10.1242/jeb.225821] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 06/16/2020] [Indexed: 12/21/2022]
Abstract
The circulatory and immune systems of mosquitoes are functionally integrated. An infection induces the migration of hemocytes to the dorsal vessel, and specifically, to the regions surrounding the ostia of the heart. These periostial hemocytes phagocytose pathogens in the areas of the hemocoel that experience the highest hemolymph flow. Here, we investigated whether a bacterial infection affects cardiac rhythmicity in the African malaria mosquito, Anopheles gambiae We discovered that infection with Escherichia coli, Staphylococcus aureus and Staphylococcus epidermidis, but not Micrococcus luteus, reduces the mosquito heart rate and alters the proportional directionality of heart contractions. Infection does not alter the expression of genes encoding crustacean cardioactive peptide (CCAP), FMRFamide, corazonin, neuropeptide F or short neuropeptide F, indicating that they do not drive the cardiac phenotype. Infection upregulates the transcription of two superoxide dismutase (SOD) genes, catalase and a glutathione peroxidase, but dramatically induces upregulation of nitric oxide synthase (NOS) in both the heart and hemocytes. Within the heart, nitric oxide synthase is produced by periostial hemocytes, and chemically inhibiting the production of nitric oxide using l-NAME reverses the infection-induced cardiac phenotype. Finally, infection induces the upregulation of two lysozyme genes in the heart and other tissues, and treating mosquitoes with lysozyme reduces the heart rate in a manner reminiscent of the infection phenotype. These data demonstrate an exciting new facet of the integration between the immune and circulatory systems of insects, whereby a hemocyte-produced factor with immune activity, namely nitric oxide, modulates heart physiology.
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Affiliation(s)
- Tania Y Estévez-Lao
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
| | - Leah T Sigle
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
| | - Scherly N Gomez
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
| | - Julián F Hillyer
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
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Kumar A, Srivastava P, Sirisena P, Dubey SK, Kumar R, Shrinet J, Sunil S. Mosquito Innate Immunity. INSECTS 2018; 9:insects9030095. [PMID: 30096752 PMCID: PMC6165528 DOI: 10.3390/insects9030095] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Revised: 06/17/2018] [Accepted: 06/18/2018] [Indexed: 12/19/2022]
Abstract
Mosquitoes live under the endless threat of infections from different kinds of pathogens such as bacteria, parasites, and viruses. The mosquito defends itself by employing both physical and physiological barriers that resist the entry of the pathogen and the subsequent establishment of the pathogen within the mosquito. However, if the pathogen does gain entry into the insect, the insect mounts a vigorous innate cellular and humoral immune response against the pathogen, thereby limiting the pathogen's propagation to nonpathogenic levels. This happens through three major mechanisms: phagocytosis, melanization, and lysis. During these processes, various signaling pathways that engage intense mosquito⁻pathogen interactions are activated. A critical overview of the mosquito immune system and latest information about the interaction between mosquitoes and pathogens are provided in this review. The conserved, innate immune pathways and specific anti-pathogenic strategies in mosquito midgut, hemolymph, salivary gland, and neural tissues for the control of pathogen propagation are discussed in detail.
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Affiliation(s)
- Ankit Kumar
- Vector Borne Diseases Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi-110067, India.
| | - Priyanshu Srivastava
- Vector Borne Diseases Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi-110067, India.
| | - Pdnn Sirisena
- Vector Borne Diseases Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi-110067, India.
| | - Sunil Kumar Dubey
- Vector Borne Diseases Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi-110067, India.
| | - Ramesh Kumar
- Vector Borne Diseases Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi-110067, India.
| | - Jatin Shrinet
- Vector Borne Diseases Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi-110067, India.
| | - Sujatha Sunil
- Vector Borne Diseases Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi-110067, India.
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8
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Parle E, Dirks JH, Taylor D. Damage, repair and regeneration in insect cuticle: The story so far, and possibilities for the future. ARTHROPOD STRUCTURE & DEVELOPMENT 2017; 46:49-55. [PMID: 27913289 DOI: 10.1016/j.asd.2016.11.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 10/12/2016] [Accepted: 11/25/2016] [Indexed: 06/06/2023]
Abstract
The exoskeleton of an insect can contain countless specializations across an individual, across developmental stages, and across the class Insecta. Hence, the exoskeleton's building material cuticle must perform a vast variety of functions. Cuticle displays a wide range of material properties which are determined by several known factors: the amount and orientation of the chitin fibres, the constituents and degree of cross-linking and hydration of the protein matrix, the relative amounts of exo- and endocuticle, and the shape of the structures themselves. In comparison to other natural materials such as wood and mammal bone, relatively few investigations into the mechanical properties of insect cuticle have been carried out. Of these, very few have focussed on the need for repair and its effectiveness at restoring mechanical stability to the cuticle. Insect body parts are often subject to prolonged repeated cyclic loads when running and flying, as well as more extreme "emergency" behaviours necessary for survival such as jumping, wedging (squeezing through small holes) and righting (when overturned). What effects have these actions on the cuticle itself? How close to the limits of failure does an insect push its body parts? Can an insect recover from minor or major damage to its exoskeleton "bones"? No current research has answered these questions conclusively.
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Affiliation(s)
- Eoin Parle
- Trinity Centre for Bioengineering, Trinity College the University of Dublin, Dublin, Ireland.
| | - Jan-Henning Dirks
- Department for Biomimetics, City University of Applied Sciences Bremen, Neustadtswall 30, 28199 Bremen, Germany
| | - David Taylor
- Trinity Centre for Bioengineering, Trinity College the University of Dublin, Dublin, Ireland
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9
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Zhao DY, Zhang MX, Dong XW, Hu YZ, Dai XY, Wei X, Hider RC, Zhang JC, Zhou T. Design and synthesis of novel hydroxypyridinone derivatives as potential tyrosinase inhibitors. Bioorg Med Chem Lett 2016; 26:3103-3108. [DOI: 10.1016/j.bmcl.2016.05.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 04/20/2016] [Accepted: 05/03/2016] [Indexed: 02/01/2023]
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10
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Hillyer JF. Insect immunology and hematopoiesis. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 58:102-18. [PMID: 26695127 PMCID: PMC4775421 DOI: 10.1016/j.dci.2015.12.006] [Citation(s) in RCA: 280] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 12/08/2015] [Accepted: 12/10/2015] [Indexed: 05/08/2023]
Abstract
Insects combat infection by mounting powerful immune responses that are mediated by hemocytes, the fat body, the midgut, the salivary glands and other tissues. Foreign organisms that have entered the body of an insect are recognized by the immune system when pathogen-associated molecular patterns bind host-derived pattern recognition receptors. This, in turn, activates immune signaling pathways that amplify the immune response, induce the production of factors with antimicrobial activity, and activate effector pathways. Among the immune signaling pathways are the Toll, Imd, Jak/Stat, JNK, and insulin pathways. Activation of these and other pathways leads to pathogen killing via phagocytosis, melanization, cellular encapsulation, nodulation, lysis, RNAi-mediated virus destruction, autophagy and apoptosis. This review details these and other aspects of immunity in insects, and discusses how the immune and circulatory systems have co-adapted to combat infection, how hemocyte replication and differentiation takes place (hematopoiesis), how an infection prepares an insect for a subsequent infection (immune priming), how environmental factors such as temperature and the age of the insect impact the immune response, and how social immunity protects entire groups. Finally, this review highlights some underexplored areas in the field of insect immunobiology.
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Affiliation(s)
- Julián F Hillyer
- Department of Biological Sciences, Vanderbilt University, VU Station B 35-1634, Nashville, TN 37235, USA.
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11
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Hillyer JF. Integrated Immune and Cardiovascular Function in Pancrustacea: Lessons from the Insects. Integr Comp Biol 2015; 55:843-55. [DOI: 10.1093/icb/icv021] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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12
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Hillyer JF, Strand MR. Mosquito hemocyte-mediated immune responses. CURRENT OPINION IN INSECT SCIENCE 2014; 3:14-21. [PMID: 25309850 PMCID: PMC4190037 DOI: 10.1016/j.cois.2014.07.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Hemocytes are a key component of the mosquito immune system that kill pathogens via phagocytic, lytic and melanization pathways. Individual mosquitoes contain between 500 and 4,000 hemocytes, which are divided into three populations named granulocytes, oenocytoids and prohemocytes. Hemocytes can also be divided by their anatomical location with 75% of hemocytes circulating in the hemocoel (circulating hemocytes) and 25% of hemocytes attaching themselves to tissues (sessile hemocytes). Greater than 85% of the hemocytes in adult mosquitoes are granulocytes, which primarily kill pathogens by phagocytosis or lysis. Oenocytoids, on the other hand, are the major producers of the enzymes required for melanization while prohemocytes are small cells that participate in phagocytosis. Both circulating and sessile hemocytes engage in defense against pathogens. The circulatory system of mosquitoes also interacts with hemocytes and facilitates elimination of potential pathogens that enter the hemocoel.
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Affiliation(s)
- Julián F. Hillyer
- Department of Biological Sciences and Institute for Global Health, Vanderbilt University, Nashville, TN, USA
| | - Michael R. Strand
- Department of Entomology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA
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13
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Hernández-Martínez S, Barradas-Bautista D, Rodríguez MH. Diferential DNA synthesis in Anopheles albimanus tissues induced by immune challenge with different microorganisms. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2013; 84:1-14. [PMID: 23797988 DOI: 10.1002/arch.21108] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The induction of DNA synthesis in various tissues of Anopheles albimanus, in response to challenge with Saccharomyces cerevisiae, Micrococcus luteus, and Serratia marcescens, was analyzed by 5-bromo-2-deoxy-uridine (BrdU) incorporation. Microorganism-inoculated mosquitoes were fed with a sucrose solution containing BrdU and maintained alive for 5 days. Alternatively, abdominal carcasses of microorganisms-inoculated mosquitoes were cultivated in Roswell Park Memorial Institute (RPMI) medium supplemented with BrdU for 5 days. Control groups were inoculated with RPMI alone. In both experiments, DNA synthesis, evidenced by epifluorescence with an anti-BrdU fluorescein-labeled antibody, occurred in fat body, epithelial cells of pleural membranes, dorsal vessel, and the oviducts. Relative quantification of DNA synthesis, evaluated by ELISA using an anti-BrdU peroxidase-labeled antibody, was higher in abdomen tissues of microorganisms-inoculated mosquitoes than controls in in vitro and in vivo experiments. The intensity of DNA synthesis varied among the different microorganism challenges, but was higher in in vivo experiments, compared to cultured samples. These differences in DNA synthesis suggest a compartmentalization of the immune response, probably mediated by different signaling pathways.
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Affiliation(s)
- Salvador Hernández-Martínez
- Centro de Investigaciones Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, Mexico
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14
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Abstract
Throughout their lifetime, mosquitoes are exposed to pathogens during feeding, through breaks in their cuticle and following pathogen-driven cuticular degradation. To resist infection, mosquitoes mount innate cellular and humoral immune responses that are elicited within minutes of exposure and can lead to pathogen death via three broadly defined mechanisms: lysis, melanization and hemocyte-mediated phagocytosis. This chapter reviews our current understanding of the mosquito immune system, with an emphasis on the physical barriers that prevent pathogens from entering the body, the organs and tissues that regulate immune responses and the mechanistic and molecular bases of immunity.
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Affiliation(s)
- Julián F Hillyer
- Department of Biological Sciences, Institute for Global Health, Vanderbilt University, Nashville, Tennessee, USA.
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15
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Abstract
Horizontally transmitted mosquito-borne viruses enter the midgut with a blood meal then disseminate to infect the salivary glands. En route to the salivary glands, these viruses encounter the plasma (haemolymph) and blood cells (haemocytes). Haemocytes respond to a variety of micro-organisms, but their role in virus replication and dissemination has not been described. To look for a potential haemocyte tropism for an arbovirus, a Sindbis virus was injected intrathoracically into four species of mosquito. Virus infects haemocytes as early as 6 h post injection (p.i.) and infection was evident in these cells for as long as 4 days p.i. More than 90 % of haemocytes were infected, most often the phagocytic granulocytes. Virus titres in the haemolymph increased from 24 h p.i. through 60 h p.i. Similar results were found when Aedes aegypti mosquitoes were injected with orally infectious Sindbis. These data prove that an arbovirus infects, and replicates in, haemocytes.
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Affiliation(s)
- Grishma R Parikh
- Department of Entomology, College of Agriculture and Life Sciences, Iowa State University, Ames, IA 50011, USA
| | - Jonathan D Oliver
- Department of Entomology, College of Agriculture and Life Sciences, Iowa State University, Ames, IA 50011, USA
| | - Lyric C Bartholomay
- Department of Entomology, College of Agriculture and Life Sciences, Iowa State University, Ames, IA 50011, USA
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16
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Liu S, Sivakumar S, Wang Z, Bonning BC, Miller WA. The readthrough domain of pea enation mosaic virus coat protein is not essential for virus stability in the hemolymph of the pea aphid. Arch Virol 2009; 154:469-79. [PMID: 19240978 DOI: 10.1007/s00705-009-0327-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Accepted: 01/16/2009] [Indexed: 10/21/2022]
Abstract
A fraction of the coat protein (CP) subunits in virions of members of the family Luteoviridae contain a C-terminal extension called the readthrough domain (RTD). The RTD is necessary for persistent aphid transmission, but its role is unknown. It has been reported to be required for virion stability in the hemolymph. Here, we tested whether this was the case for pea enation mosaic virus (PEMV) virions in the pea aphid (Acyrthosiphon pisum) using RNA1Delta, a natural deletion mutant lacking the middle portion of the RTD ORF, and CPDeltaRTD, in which the entire RTD ORF was deleted. In infected plants, RNA1Delta virions were as abundant and stable as wild-type (WT) virions, while CPDeltaRTD virions were unstable. No RTD of any size was translated from artificial subgenomic mRNA of CPDeltaRTD or RNA1Delta in vitro. Thus, only the major CP was present in the mutant virions. Using real-time RT-PCR to detect virion RNA, no significant differences in the concentration or stability of WT and RNA1Delta virions were detected in the aphid hemolymph at much longer times than are necessary for virus transmission. Thus, the RTD is not necessary for stability of PEMV RNA in the aphid hemolymph, and it must play another role in aphid transmission.
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Affiliation(s)
- Sijun Liu
- Department of Entomology, 418 Science II, Iowa State University, Ames, IA 50011, USA
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17
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Tsao IY, Lin US, Christensen BM, Chen CC. Armigeres subalbatus prophenoloxidase III: Cloning, characterization and potential role in morphogenesis. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2009; 39:96-104. [PMID: 19013240 DOI: 10.1016/j.ibmb.2008.10.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 08/27/2008] [Accepted: 10/09/2008] [Indexed: 05/27/2023]
Abstract
It has long been suggested that phenoloxidases (POs) play key roles in various physiological functions in insects, e.g., cuticular sclerotization, wound healing, egg tanning and melanotic encapsulation of pathogens. Here we report that a mosquito PO, designated Armigeres subalbatus prophenoloxidase III (As-pro-PO III), is likely involved in the morphogenesis in mosquito. Expression profile analysis found that As-pro-PO III mRNA is persistently expressed in adult mosquitoes and is not significantly affected by blood feeding, microfilariae inoculation, or Escherichia coli inoculation, but expression levels of As-pro-PO III fluctuated in larval and pupal stages. Knockdown of As-pro-PO III expression in pupae using double-stranded RNA resulted in high pupal mortality and deformed adults that subsequently died following emergence. Promoter activity analyses by electrophoretic mobility-shift assays and transfection assays suggest that the As-pro-PO III gene is positively regulated by a putative Zeste motif, a developmental regulatory element. These results suggest that As-pro-PO III is associated with morphogenesis of mosquitoes.
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Affiliation(s)
- I-Y Tsao
- Department of Tropical Medicine, National Yang-Ming University, Shih-Pai, Taipei 112, Taiwan
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Hernández-Martínez S, Román-Martínez U, Martínez-Barnetche J, Garrido E, Rodríguez MH, Lanz-Mendoza H. Induction of DNA synthesis in Anopheles albimanus tissue cultures in response to a Saccharomyces cerevisiae challenge. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2006; 63:147-58. [PMID: 17103404 DOI: 10.1002/arch.20150] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
DNA synthesis was detected by the incorporation of 5-bromo-2' deoxy-uridine (BrdU) in adult Anopheles albimanus organs in culture in response to a challenge with Saccharomyces cerevisiae. Abdomens of mosquitoes inoculated with Roswell Park Memorial Institute medium (RPMI, control) or yeast were cultivated in RPMI plus ConA and BrdU for 5 days. DNA was obtained by phenolic extraction and the incorporated BrdU was quantified by ELISA using anti-BrdU peroxidase-labeled antibodies. Abdomen tissues of mosquitoes inoculated with yeast showed higher DNA synthesis than controls. Organs from untreated mosquitoes cultured in the presence of zymosan also synthesized DNA but at a lower level than tissues from yeast-inoculated mosquitoes. In similar experiments, DNA synthesis was inhibited by the addition of colchicine. DNA synthesis, evidenced by epifluorescence using an anti-BrdU fluorescein-labeled antibody, occurred in fat body, epithelial cells in pleural membranes, and the dorsal vessel. Pleural membranes showed the highest number of labeled cells. These tissues were also labeled with anti-PCNA (proliferating cell nuclear antigen) antibodies, two of which were able to produce polytene chromosomes under yeast stimulation. These results demonstrate that different An. albimanus tissues undergo DNA synthesis in response to foreign particles.
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Affiliation(s)
- S Hernández-Martínez
- Centro de Investigaciones Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, México
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Hillyer JF, Schmidt SL, Fuchs JF, Boyle JP, Christensen BM. Age-associated mortality in immune challenged mosquitoes (Aedes aegypti) correlates with a decrease in haemocyte numbers. Cell Microbiol 2005; 7:39-51. [PMID: 15617522 DOI: 10.1111/j.1462-5822.2004.00430.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mosquitoes vector pathogens. One aspect that has been overlooked in mosquito-pathogen relationships is the effect of host age on immune competence. Here, we show that there is age-associated mortality following immune challenge with Escherichia coli. This mortality correlates with a decrease in haemocyte numbers (blood cells) and a decreased ability to kill E. coli. Although the number of haemocytes decreases, the available haemocytes retain their phagocytic ability regardless of age, and we estimate that individual granulocytes can phagocytose approximately 1500 E. coli. Moreover, transcription profiles for cecropin, defensin and gambicin in E. coli challenged mosquitoes do not change with age, indicating that the increased susceptibility is not attributed to fewer humoral antimicrobial peptides. These results suggest that a contributing factor for the age-associated mortality is the decrease in circulating haemocytes, which reduces the overall phagocytic capacity of mosquitoes. To our knowledge, this is the first report detailing an age-associated decline in the immunological capabilities of mosquitoes following challenge with an infectious agent. These data also call for caution in the analysis and interpretation of experimental results when mosquito age has not been closely monitored. Lastly, a model for haemocyte function is presented.
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Affiliation(s)
- Julián F Hillyer
- Department of Animal Health and Biomedical Sciences, University of Wisconsin-Madison, 1656 Linden Drive, Madison, WI 53706, USA
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Lai SC, Chen CC, Hou RF. Immunolocalization of prophenoloxidase in the process of wound healing in the mosquito Armigeres subalbatus (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2002; 39:266-274. [PMID: 11931025 DOI: 10.1603/0022-2585-39.2.266] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Hemolymph coagulation began almost immediately after wounding in mosquito, Armigeres subalbatus, (Coquillett) larvae. Immunocytochemical localization showed that prophenoloxidase (pro-PO) was distributed in the wound site. In the initial wounding, coagulation and wound plug formation occurred with granulocyte migration. The hemocytes lysed and released granular materials around the wound site, prophenoloxidase being mostly localized in granules and cuticle. In the second phase of wound healing, melanin accumulation occurred at the wound site along the margin of the cuticle and rapidly increased in thickness. Immunogold-labeled pro-PO was localized in vacuoles, melanins, and cuticle, with the gold particles labeled intensely on the undarkened cuticle and weakly on the darkened cuticle. It is believed that pro-PO is activated upon wound initiation to produce melanin product and deposited on the cuticle. In the final phase of healing, scab melanization and pro-PO immunogold localization were reduced and accompanied by epithelial cell regeneration. This proenzyme was localized in vesicles and flocculent materials, but was absent in the melanized scab. Our results further indicate that pro-PO was present in granules, cuticles, epithelial cells, vacuoles, and flocculent materials but not in melanized scab and coagulated clot. The pro-PO immunogold particles labeled intensely in the initial wounding but weakly in the final phase. Our observations also suggest that pro-PO is released from granulocytes by cell rupture, synthesized or stored in granulocytes, and then is released into the wound site via the cytoplasmic granules. This study indicates that the pro-PO is involved in numerous physiological roles in the process of wound healing in this mosquito.
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Affiliation(s)
- Shih-Chan Lai
- Department of Entomology, National Chung-Hsing University, Taichung, Taiwan, ROC
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