1
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Osborne CJ, Su T, Silver KS, Cohnstaedt LW. Variable gut pH as a potential mechanism of tolerance to Bacillus thuringiensis subsp. israelensis toxins in the biting midge Culicoides sonorensis. PEST MANAGEMENT SCIENCE 2024; 80:4006-4012. [PMID: 38527917 DOI: 10.1002/ps.8104] [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: 12/22/2023] [Revised: 03/04/2024] [Accepted: 03/24/2024] [Indexed: 03/27/2024]
Abstract
BACKGROUND Toxins of Bacillus thuringiensis subsp. israelensis (Bti) are safer alternatives for controlling dipteran pests such as black flies and mosquitoes. The biting midge Culicoides sonorensis (Diptera: Ceratopogonidae) is an important pest of livestock in much of the United States and larval midges utilize semi-aquatic habitats which are permissive for Bti product application. Reports suggest that Bti products are ineffective at killing biting midges despite their taxonomic relation to black flies and mosquitoes. Here, we investigate the toxicity of a Bti-based commercial insecticide and its active ingredient in larval Culicoides sonorensis. A suspected mechanism of Bti tolerance is an acidic larval gut, and we used a pH indicator dye to examine larval Culicoides sonorensis gut pH after exposure to Bti. RESULTS The lethal concentration to kill 90% (LC90) of larvae of the commercial product (386 mg/L) was determined to be almost 10 000 times more than that of some mosquito species, and no concentration of active ingredient tested achieved 50% larval mortality. The larval gut was found to be more acidic after exposure to Bti which inhibits Bti toxin activity. By comparison, 100% mortality was achieved in larval Aedes aegypti at the product's label rate for this species and mosquito larvae had alkaline guts regardless of treatment. Altering the larval rearing water to alkaline conditions enhanced Bti efficacy when using the active ingredient. CONCLUSION We conclude that Bti is not practical for larval Culicoides sonorensis control at the same rates as mosquitos but show that alterations or additives to the environment could make the products more effective. © 2024 Society of Chemical Industry.
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Affiliation(s)
- Cameron J Osborne
- Department of Entomology, Kansas State University, Manhattan, KS, USA
| | - Tianyun Su
- EcoZone International, Riverside, CA, USA
| | | | - Lee W Cohnstaedt
- Foreign Arthropod-Borne Animal Diseases Research Unit, Agricultural Research Service, United States Department of Agriculture, Manhattan, KS, USA
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2
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Rios T, Maximiano MR, Fernandes FC, Amorim GC, Porto WF, Buccini DF, Nieto Marín V, Feitosa GC, Freitas CDP, Barra JB, Alonso A, Grossi de Sá MF, Lião LM, Franco OL. Anti-Staphy Peptides Rationally Designed from Cry10Aa Bacterial Protein. ACS OMEGA 2024; 9:29159-29174. [PMID: 39005792 PMCID: PMC11238290 DOI: 10.1021/acsomega.3c07455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 06/03/2024] [Accepted: 06/05/2024] [Indexed: 07/16/2024]
Abstract
Bacterial infections pose a significant threat to human health, constituting a major challenge for healthcare systems. Antibiotic resistance is particularly concerning in the context of treating staphylococcal infections. In addressing this challenge, antimicrobial peptides (AMPs), characterized by their hydrophobic and cationic properties, unique mechanism of action, and remarkable bactericidal and immunomodulatory capabilities, emerge as promising alternatives to conventional antibiotics for tackling bacterial multidrug resistance. This study focuses on the Cry10Aa protein as a template for generating AMPs due to its membrane-penetrating ability. Leveraging the Joker algorithm, six peptide variants were derived from α-helix 3 of Cry10Aa, known for its interaction with lipid bilayers. In vitro, antimicrobial assays determined the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) required for inhibiting the growth of Staphylococcus aureus, Escherichia coli, Acinetobacter baummanii, Enterobacter cloacae, Enterococcus facallis, Klebsiella pneumonia, and Pseudomonas aeruginosa. Time-kill kinetics were performed using the parental peptide AMPCry10Aa, as well as AMPCry10Aa_1 and AMPCry10Aa_5, against E. coli ATCC, S. aureus 111 and S. aureus ATCC strains showing that AMPCry10Aa_1 and AMPCry10Aa_5 peptides can completely reduce the initial bacterial load with less than 2 h of incubation. AMPCry10Aa_1 and AMPCry 10Aa_5 present stability in human serum and activity maintenance up to 37 °C. Cytotoxicity assays, conducted using the MTT method, revealed that all of the tested peptides exhibited cell viability >50% (IC50). The study also encompassed evaluations of the structure and physical-chemical properties. The three-dimensional structures of AMPCry10Aa and AMPCry10Aa_5 were determined through nuclear magnetic resonance (NMR) spectroscopy, indicating the adoption of α-helical segments. Electron paramagnetic resonance (EPR) spectroscopy elucidated the mechanism of action, demonstrating that AMPCry10Aa_5 enters the outer membranes of E. coli and S. aureus, causing substantial increases in lipid fluidity, while AMPCry10Aa slightly increases lipid fluidity in E. coli. In conclusion, the results obtained underscore the potential of Cry10Aa as a source for developing antimicrobial peptides as alternatives to conventional antibiotics, offering a promising avenue in the battle against antibiotic resistance.
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Affiliation(s)
- Thuanny
Borba Rios
- S-Inova
Biotech, Programa de Pós-Graduação
em Biotecnologia Universidade Católica Dom Bosco, Av. Tamandaré, 6000—Jardim
Seminario, Campo Grande, MS 79117-900, Brazil
- Centro
de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em
Ciências Genômicas e Biotecnologia Universidade Católica
de Brasília, St.
de Grandes Áreas Norte 916—Asa Norte, Brasília, DF 70790-160, Brazil
| | - Mariana Rocha Maximiano
- S-Inova
Biotech, Programa de Pós-Graduação
em Biotecnologia Universidade Católica Dom Bosco, Av. Tamandaré, 6000—Jardim
Seminario, Campo Grande, MS 79117-900, Brazil
- Centro
de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em
Ciências Genômicas e Biotecnologia Universidade Católica
de Brasília, St.
de Grandes Áreas Norte 916—Asa Norte, Brasília, DF 70790-160, Brazil
| | - Fabiano Cavalcanti Fernandes
- Centro
de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em
Ciências Genômicas e Biotecnologia Universidade Católica
de Brasília, St.
de Grandes Áreas Norte 916—Asa Norte, Brasília, DF 70790-160, Brazil
| | - Gabriella Cavalcante Amorim
- Centro
de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em
Ciências Genômicas e Biotecnologia Universidade Católica
de Brasília, St.
de Grandes Áreas Norte 916—Asa Norte, Brasília, DF 70790-160, Brazil
- Embrapa
Recursos Genéticos e Biotecnologia, Parque Estação Biológica, PqEB, Av. W5 Norte—Asa Norte, Brasília, DF 70770-917, Brazil
| | | | - Danieli Fernanda Buccini
- S-Inova
Biotech, Programa de Pós-Graduação
em Biotecnologia Universidade Católica Dom Bosco, Av. Tamandaré, 6000—Jardim
Seminario, Campo Grande, MS 79117-900, Brazil
| | - Valentina Nieto Marín
- S-Inova
Biotech, Programa de Pós-Graduação
em Biotecnologia Universidade Católica Dom Bosco, Av. Tamandaré, 6000—Jardim
Seminario, Campo Grande, MS 79117-900, Brazil
| | - Gabriel Cidade Feitosa
- Centro
de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em
Ciências Genômicas e Biotecnologia Universidade Católica
de Brasília, St.
de Grandes Áreas Norte 916—Asa Norte, Brasília, DF 70790-160, Brazil
- Pós-Graduação
em Patologia Molecular, Universidade de
Brasília, Campus
Darcy Ribeiro, Brasília, DF 70910-900, Brazil
| | | | - Juliana Bueno Barra
- Laboratório
de RMN, Instituto de Química, Universidade
Federal de Goiás, Goiânia, GO 74690-900, Brazil
| | - Antonio Alonso
- Instituto
de Física, Universidade Federal de
Goiás, Goiânia, GO 74690-900, Brazil
| | - Maria Fátima Grossi de Sá
- Centro
de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em
Ciências Genômicas e Biotecnologia Universidade Católica
de Brasília, St.
de Grandes Áreas Norte 916—Asa Norte, Brasília, DF 70790-160, Brazil
- Embrapa
Recursos Genéticos e Biotecnologia, Parque Estação Biológica, PqEB, Av. W5 Norte—Asa Norte, Brasília, DF 70770-917, Brazil
| | - Luciano Morais Lião
- Laboratório
de RMN, Instituto de Química, Universidade
Federal de Goiás, Goiânia, GO 74690-900, Brazil
| | - Octávio Luiz Franco
- S-Inova
Biotech, Programa de Pós-Graduação
em Biotecnologia Universidade Católica Dom Bosco, Av. Tamandaré, 6000—Jardim
Seminario, Campo Grande, MS 79117-900, Brazil
- Centro
de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em
Ciências Genômicas e Biotecnologia Universidade Católica
de Brasília, St.
de Grandes Áreas Norte 916—Asa Norte, Brasília, DF 70790-160, Brazil
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3
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Oskoei P, Marçal R, Oliveira H, Guilherme S. Hitting two targets with one shot on pesticide genotoxicity assessment - Identifying risk while unveiling ex vivo approach as a throughput tool in gill-breathing animals. JOURNAL OF HAZARDOUS MATERIALS 2024; 476:134948. [PMID: 38968824 DOI: 10.1016/j.jhazmat.2024.134948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 06/14/2024] [Accepted: 06/16/2024] [Indexed: 07/07/2024]
Abstract
Pesticides in the environment often compromise the ecosystem, thus requiring reliable approaches to assess their effects. Commonly used approaches, such as in vivo, come with several disadvantages, namely in the light of the 3 R's policy. Seeking for accurate and ethical approaches, this study intended to validate the ex vivo technique as an alternative, and to assess the genotoxicity of chemically-based pesticides and a biopesticide. The ex vivo approach was applied to gill cells of Procambarus clarkii for 2, 4 and 8 h. Cell viability and DNA integrity were evaluated to determine the applicability of this approach. Crayfish gill cells only showed to be suitable for exposures of 2 h. Accordingly, genotoxicity was evaluated in gill cells exposed, for 2 h, to environmentally relevant concentrations of the chemically-based pesticides dimethoate (20 µg L-1), imazalil (160 µg L-1) and penoxsulam (23 µg L-1), as well as to the bioinsecticide Turex® (25, 50, 100, 200 and 400 µg L-1). Every chemically-based pesticide demonstrated to be genotoxic, despite not inducing oxidative DNA damage. On the other hand, Turex® showed no genotoxic effects. Overall, the ex vivo approach demonstrated to be possible and practical to implement, improving the number of outcomes with a lower number of organisms. The findings from the screening test suggest that biological pesticides may pose a lower risk to non-target organisms compared to chemically-based pesticides.
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Affiliation(s)
- Párástu Oskoei
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal.
| | - Raquel Marçal
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal
| | - Helena Oliveira
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal
| | - Sofia Guilherme
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal
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4
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Wang YX, Yang HJ, Zhang WJ, Zhao XH, Cui MY, Zhang JB, Zhang XX, Fan D. Antimicrobial peptide cecropin B functions in pathogen resistance of Mythimna separata. BULLETIN OF ENTOMOLOGICAL RESEARCH 2024; 114:281-292. [PMID: 38602247 DOI: 10.1017/s0007485324000130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Mythimna separata (Lepidoptera: Noctuidae) is an omnivorous pest that poses a great threat to food security. Insect antimicrobial peptides (AMPs) are small peptides that are important effector molecules of innate immunity. Here, we investigated the role of the AMP cecropin B in the growth, development, and immunity of M. separata. The gene encoding M. separata cecropin B (MscecropinB) was cloned. The expression of MscecropinB was determined in different developmental stages and tissues of M. separata. It was highest in the prepupal stage, followed by the pupal stage. Among larval stages, the highest expression was observed in the fourth instar. Tissue expression analysis of fourth instar larvae showed that MscecropinB was highly expressed in the fat body and haemolymph. An increase in population density led to upregulation of MscecropinB expression. MscecropinB expression was also upregulated by the infection of third and fourth instar M. separata with Beauveria bassiana or Bacillus thuringiensis (Bt). RNA interference (RNAi) targeting MscecropinB inhibited the emergence rate and fecundity of M. separata, and resulted in an increased sensitivity to B. bassiana and Bt. The mortality of M. separata larvae was significantly higher in pathogen plus RNAi-treated M. separata than in controls treated with pathogens only. Our findings indicate that MscecropinB functions in the eclosion and fecundity of M. separata and plays an important role in resistance to infection by B. bassiana and Bt.
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Affiliation(s)
- Yi-Xiao Wang
- College of Plant Protection, Northeast Agricultural University, Harbin, China
| | - Hong-Jia Yang
- College of Plant Protection, Northeast Agricultural University, Harbin, China
| | - Wei-Jia Zhang
- College of Plant Protection, Northeast Agricultural University, Harbin, China
| | - Xiao-Hui Zhao
- College of Plant Protection, Northeast Agricultural University, Harbin, China
| | - Meng-Yao Cui
- College of Plant Protection, Northeast Agricultural University, Harbin, China
| | - Jin-Bo Zhang
- College of Plant Protection, Northeast Agricultural University, Harbin, China
| | - Xin-Xin Zhang
- College of Plant Protection, Northeast Agricultural University, Harbin, China
| | - Dong Fan
- College of Plant Protection, Northeast Agricultural University, Harbin, China
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5
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Steinigeweg C, Alkassab AT, Erler S, Beims H, Wirtz IP, Richter D, Pistorius J. Impact of a Microbial Pest Control Product Containing Bacillus thuringiensis on Brood Development and Gut Microbiota of Apis mellifera Worker Honey Bees. MICROBIAL ECOLOGY 2023; 85:1300-1307. [PMID: 35389085 PMCID: PMC10167108 DOI: 10.1007/s00248-022-02004-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 03/28/2022] [Indexed: 05/10/2023]
Abstract
To avoid potential adverse side effects of chemical plant protection products, microbial pest control products (MPCP) are commonly applied as biological alternatives. This study aimed to evaluate the biosafety of a MPCP with the active organism Bacillus thuringiensis ssp. aizawai (strain: ABTS-1857). An in-hive feeding experiment was performed under field-realistic conditions to examine the effect of B. thuringiensis (B. t.) on brood development and the bacterial abundance of the core gut microbiome (Bifidobacterium asteroids, Gilliamella apicola, the group of Lactobacillus and Snodgrasella alvi) in Apis mellifera worker bees. We detected a higher brood termination rate and a non-successful development into worker bees of treated colonies compared to those of the controls. For the gut microbiome, all tested core members showed a significantly lower normalized abundance in bees of the treated colonies than in those of the controls; thus, a general response of the gut microbiome may be assumed. Consequently, colony exposure to B. t. strain ABTS-1857 had a negative effect on brood development under field-realistic conditions and caused dysbiosis of the gut microbiome. Further studies with B. t.-based products, after field-realistic application in bee attractive crops, are needed to evaluate the potential risk of these MPCPs on honey bees.
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Affiliation(s)
| | - Abdulrahim T Alkassab
- Institute for Bee Protection, Julius Kühn-Institut (JKI) - FederalResearch Centre for Cultivated Plants, Braunschweig, Germany.
| | - Silvio Erler
- Institute for Bee Protection, Julius Kühn-Institut (JKI) - FederalResearch Centre for Cultivated Plants, Braunschweig, Germany
| | - Hannes Beims
- Institute for Apiculture, Lower Saxony State Office for Consumer Protection and Food Safety (LAVES), Celle, Germany
| | - Ina P Wirtz
- Institute for Bee Protection, Julius Kühn-Institut (JKI) - FederalResearch Centre for Cultivated Plants, Braunschweig, Germany
| | - Dania Richter
- Institute of Geoecology, Technische Universität Braunschweig, Braunschweig, Germany
| | - Jens Pistorius
- Institute for Bee Protection, Julius Kühn-Institut (JKI) - FederalResearch Centre for Cultivated Plants, Braunschweig, Germany
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6
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Narayanan Z, Glick BR. Biotechnologically Engineered Plants. BIOLOGY 2023; 12:biology12040601. [PMID: 37106801 PMCID: PMC10135915 DOI: 10.3390/biology12040601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 04/08/2023] [Accepted: 04/13/2023] [Indexed: 04/29/2023]
Abstract
The development of recombinant DNA technology during the past thirty years has enabled scientists to isolate, characterize, and manipulate a myriad of different animal, bacterial, and plant genes. This has, in turn, led to the commercialization of hundreds of useful products that have significantly improved human health and well-being. Commercially, these products have been mostly produced in bacterial, fungal, or animal cells grown in culture. More recently, scientists have begun to develop a wide range of transgenic plants that produce numerous useful compounds. The perceived advantage of producing foreign compounds in plants is that compared to other methods of producing these compounds, plants seemingly provide a much less expensive means of production. A few plant-produced compounds are already commercially available; however, many more are in the production pipeline.
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Affiliation(s)
- Zareen Narayanan
- Division of Biological Sciences, School of STEM, University of Washington, Bothell, WA 98011, USA
| | - Bernard R Glick
- Department of Biology, University of Waterloo, Waterloo, ON N2L3G1, Canada
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7
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Zhao W, Poncet-Legrand C, Staunton S, Quiquampoix H. pH-Dependent Changes in Structural Stabilities of Bt Cry1Ac Toxin and Contrasting Model Proteins following Adsorption on Montmorillonite. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:5693-5702. [PMID: 36989144 DOI: 10.1021/acs.est.2c09310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The environmental fate of insecticidal Cry proteins, including time-dependent conservation of biological properties, results from their structural stability in soils. The complex cascade of reactions involved in biological action requires Cry proteins to be in solution. However, the pH-dependent changes in conformational stability and the adsorption-desorption mechanisms of Cry protein on soil minerals remain unclear. We used Derjaguin-Landau-Verwey-Overbeek (DLVO) calculation and differential scanning calorimetry to interpret the driving forces and structural stabilities of Cry1Ac and two contrasting model proteins adsorbed by montmorillonite. The structural stability of Cry1Ac is closer to that of the "hard" protein, α-chymotrypsin, than that of the "soft" bovine serum albumin (BSA). The pH-dependent adsorption of Cry1Ac and α-chymotrypsin could be explained by DLVO theory, whereas the BSA adsorption deviated from it. Patch-controlled electrostatic attraction, hydrophobic effects, and entropy changes following protein unfolding on a mineral surface could contribute to Cry1Ac adsorption. Cry1Ac, like chymotrypsin, was partly denatured on montmorillonite, and its structural stability decreased with an increase in pH. Moreover, small changes in the conformational heterogeneity of both Cry1Ac and chymotrypsin were observed following adsorption. Conversely, adsorbed BSA was completely denatured regardless of the solution pH. The moderate conformational rearrangement of adsorbed Cry1Ac may partially explain why the insecticidal activity of Bt toxin appears to be conserved in soils, albeit for a relatively short time period.
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Affiliation(s)
- Wenqiang Zhao
- Eco&Sols, INRAE, IRD, Cirad, Institut Agro, Univ Montpellier, 34090 Montpellier, France
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization and Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
| | | | - Siobhan Staunton
- Eco&Sols, INRAE, IRD, Cirad, Institut Agro, Univ Montpellier, 34090 Montpellier, France
| | - Hervé Quiquampoix
- Eco&Sols, INRAE, IRD, Cirad, Institut Agro, Univ Montpellier, 34090 Montpellier, France
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8
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Guerrero M. GG. Sporulation, Structure Assembly, and Germination in the Soil Bacterium Bacillus thuringiensis: Survival and Success in the Environment and the Insect Host. MICROBIOLOGY RESEARCH 2023. [DOI: 10.3390/microbiolres14020035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023] Open
Abstract
Bacillus thuringiensis (Bt) is a rod-shaped, Gram-positive soil bacterium that belongs to the phylum Firmicutes and the genus Bacillus. It is a spore-forming bacterium. During sporulation, it produces a wide range of crystalline proteins that are toxic to different orders of insects. Sporulation, structure assembly, and germination are essential stages in the cell cycle of B. thuringiensis. The majority of studies on these issues have focused on the model organism Bacillus subtilis, followed by Bacillus cereus and Bacillus anthracis. The machinery for sporulation and germination extrapolated to B. thuringiensis. However, in the light of recent findings concerning the role of the sporulation proteins (SPoVS), the germination receptors (Gr), and the cortical enzymes in Bt, the theory strengthened that conservation in sporulation, structure assembly, and germination programs drive the survival and success of B. thuringiensis in the environment and the insect host. In the present minireview, the latter pinpointed and reviewed.
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Affiliation(s)
- Gloria G. Guerrero M.
- Unidad Académica de Ciencias Biológicas, Laboratorio de Immunobiología, Universidad Autónoma de Zacatecas, Av. Preparatoria S/N, Col. Agronomicas, Zacatecas 98066, Mexico
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9
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Nithya K, Bhuvaragavan S, Sruthi K, Meenakumari M, Shanthi S, Janarthanan S. Purification, characterization and larvicidal activity of a potent bioactive compound asarone from leaves of Acorus calamus against the culician larval mosquitoes. Parasitol Int 2022; 90:102620. [DOI: 10.1016/j.parint.2022.102620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 06/11/2022] [Accepted: 06/28/2022] [Indexed: 10/17/2022]
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10
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Biggel M, Jessberger N, Kovac J, Johler S. Recent paradigm shifts in the perception of the role of Bacillus thuringiensis in foodborne disease. Food Microbiol 2022; 105:104025. [DOI: 10.1016/j.fm.2022.104025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 03/10/2022] [Accepted: 03/11/2022] [Indexed: 12/16/2022]
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11
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Wang X, Yi XL, Hou CX, Wang XY, Sun X, Zhang ZJ, Qin S, Li MW. Map-based cloning and functional analysis revealed ABCC2 is responsible for Cry1Ac toxin resistance in Bombyx mori. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2022; 110:e21886. [PMID: 35307854 DOI: 10.1002/arch.21886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 02/22/2022] [Accepted: 03/08/2022] [Indexed: 06/14/2023]
Abstract
Bt toxins are parasporal crystals produced by Bacillus thuringiensis (Bt). They have specific killing activity against various insects and have been widely used to control agricultural pests. However, their widespread use has developed the resistance of many target insects. To maintain the sustainable use of Bt products, the resistance mechanism of insects to Bt toxins must be fully clarified. In this study, Bt-resistant and Bt-susceptible silkworm strains were used to construct genetic populations, and the genetic pattern of silkworm resistance to Cry1Ac toxin was determined. Sequence-tagged site molecular marker technology was used to finely map the resistance gene and to draw a molecular genetic linkage map, and the two closest markers were T1590 and T1581, indicating the resistance gene located in the 155 kb genetic region. After analyzing the sequence of the predicted gene in the genetic region, an ATP binding cassette transporter (ABCC2) was identified as the candidate gene. Molecular modeling and protein-protein docking result showed that a tyrosine insertion in the mutant ABCC2 might be responsible for the interaction between Cry1Ac and ABCC2. Moreover, CRISPR/Cas9-mediated genome editing technology was used to knockout ABCC2 gene. The homozygous mutant ABCC2 silkworm was resistant to Cry1Ac toxin, which indicated ABCC2 is the key gene that controls silkworm resistance to Cry1Ac toxin. The results have laid the foundation for elucidating the molecular resistance mechanism of silkworms to Cry1Ac toxin and could provide a theoretical basis for the biological control of lepidopteran pests.
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Affiliation(s)
- Xin Wang
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
| | - Xiao-Li Yi
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
| | - Cheng-Xiang Hou
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
- Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Science, Zhenjiang, Jiangsu, China
| | - Xue-Yang Wang
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
- Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Science, Zhenjiang, Jiangsu, China
| | - Xia Sun
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
- Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Science, Zhenjiang, Jiangsu, China
| | - Zhong-Jie Zhang
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
| | - Sheng Qin
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
- Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Science, Zhenjiang, Jiangsu, China
| | - Mu-Wang Li
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
- Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Science, Zhenjiang, Jiangsu, China
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12
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Mechanisms and Applications of Bacterial Sporulation and Germination in the Intestine. Int J Mol Sci 2022; 23:ijms23063405. [PMID: 35328823 PMCID: PMC8953710 DOI: 10.3390/ijms23063405] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/15/2022] [Accepted: 03/18/2022] [Indexed: 02/04/2023] Open
Abstract
Recent studies have suggested a major role for endospore forming bacteria within the gut microbiota, not only as pathogens but also as commensal and beneficial members contributing to gut homeostasis. In this review the sporulation processes, spore properties, and germination processes will be explained within the scope of the human gut. Within the gut, spore-forming bacteria are known to interact with the host’s immune system, both in vegetative cell and spore form. Together with the resistant nature of the spore, these characteristics offer potential for spores’ use as delivery vehicles for therapeutics. In the last part of the review, the therapeutic potential of spores as probiotics, vaccine vehicles, and drug delivery systems will be discussed.
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13
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Khorramnejad A, Bel Y, Talaei-Hassanloui R, Escriche B. Activation of Bacillus thuringiensis Cry1I to a 50 kDa stable core impairs its full toxicity to Ostrinia nubilalis. Appl Microbiol Biotechnol 2022; 106:1745-1758. [PMID: 35138453 PMCID: PMC8882101 DOI: 10.1007/s00253-022-11808-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/28/2021] [Accepted: 01/26/2022] [Indexed: 11/30/2022]
Abstract
Bacillus thuringiensis Cry1I insecticidal proteins are structurally similar to other three-domain Cry proteins, although their size, activity spectrum, and expression at the stationary phase are unique among other members of the Cry1 family. The mode of action of Cry1 proteins is not completely understood but the existence of an activation step prior to specific binding is widely accepted. In this study, we attempted to characterize and determine the importance of the activation process in the mode of action of Cry1I, as Cry1Ia protoxin or its partially processed form showed significantly higher toxicity to Ostrinia nubilalis than the fully processed protein either activated with trypsin or with O. nubilalis midgut juice. Oligomerization studies showed that Cry1Ia protoxin, in solution, formed dimers spontaneously, and the incubation of Cry1Ia protoxin with O. nubilalis brush border membrane vesicles (BBMV) promoted the formation of dimers of the partially processed form. While no oligomerization of fully activated proteins after incubation with BBMV was detected. The results of the in vitro competition assays showed that both the Cry1Ia protoxin and the approx. 50 kDa activated proteins bind specifically to the O. nubilalis BBMV and compete for the same binding sites. Accordingly, the in vivo binding competition assays show a decrease in toxicity following the addition of an excess of 50 kDa activated protein. Consequently, as full activation of Cry1I protein diminishes its toxicity against lepidopterans, preventing or decelerating proteolysis might increase the efficacy of this protein in Bt-based products. KEY POINTS: • Processing Cry1I to a 50 kDa stable core impairs its full toxicity to O. nubilalis • Partially processed Cry1Ia protoxin retains the toxicity of protoxin vs O. nubilalis • Protoxin and its final processed forms compete for the same functional binding sites.
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Affiliation(s)
- Ayda Khorramnejad
- Laboratory of Biotechnological Control of Pests, Departamento de Genética, Instituto BioTecMed, Universitat de València, Burjassot, València, Spain.,Laboratory of Biological Control of Pest, Department of Plant Protection, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran
| | - Yolanda Bel
- Laboratory of Biotechnological Control of Pests, Departamento de Genética, Instituto BioTecMed, Universitat de València, Burjassot, València, Spain.
| | - Reza Talaei-Hassanloui
- Laboratory of Biological Control of Pest, Department of Plant Protection, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran
| | - Baltasar Escriche
- Laboratory of Biotechnological Control of Pests, Departamento de Genética, Instituto BioTecMed, Universitat de València, Burjassot, València, Spain.
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14
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Marques LH, Lepping M, Castro BA, Santos AC, Rossetto J, Nunes MZ, Silva OABN, Moscardini VF, de Sá VGM, Nowatzki T, Dahmer ML, Gontijo PC. Field efficacy of Bt cotton containing events DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 against lepidopteran pests and impact on the non-target arthropod community in Brazil. PLoS One 2021; 16:e0251134. [PMID: 33945577 PMCID: PMC8096009 DOI: 10.1371/journal.pone.0251134] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 04/21/2021] [Indexed: 11/19/2022] Open
Abstract
The efficacy and non-target arthropod effects of transgenic DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 Bt cotton, expressing proteins Cry1Ac, Cry1F and Vip3Aa19, was examined through field trials in Brazil. Fifteen field efficacy experiments were conducted from 2014 through the 2020 growing season across six different states in Brazil to evaluate performance against key lepidopteran pests through artificial infestations of Chrysodeixis includens (Walker), Spodoptera frugiperda (J.E. Smith,1797), Spodoptera cosmioides (Walker, 1858) and Chloridea virescens (F., 1781), and natural infestations of Alabama argillacea (Hübner) and S. frugiperda. The impact of this Bt cotton technology on the non-target arthropod community in Brazilian cotton production systems was also assessed in a multi-site experiment. DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton significantly reduced the feeding damage caused by S. frugiperda, S. cosmioides, C. includens, C. virescens and A. argillacea, causing high levels of mortality (greater than 99%) to all target lepidopteran pests evaluated during vegetative and/or reproductive stages of crop development. Non-target arthropod community-level analyses confirmed no unintended effects on the arthropod groups monitored. These results demonstrate the value of transgenic Bt cotton containing event DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 for consideration as part of an integrated approach for managing key lepidopteran pests in Brazilian cotton production systems.
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Affiliation(s)
| | - Miles Lepping
- Corteva Agriscience, Indianapolis, Indiana, United States of America
| | - Boris A. Castro
- Corteva Agriscience, Indianapolis, Indiana, United States of America
| | | | | | | | | | | | | | | | - Mark L. Dahmer
- Corteva Agriscience, Johnston, Iowa, United States of America
| | - Pablo C. Gontijo
- Instituto Federal Goiano, Campus Rio Verde, Rio Verde, Goiás, Brazil
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15
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Iqbal A, Khan RS, Khan MA, Gul K, Jalil F, Shah DA, Rahman H, Ahmed T. Genetic Engineering Approaches for Enhanced Insect Pest Resistance in Sugarcane. Mol Biotechnol 2021; 63:557-568. [PMID: 33893996 DOI: 10.1007/s12033-021-00328-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 04/19/2021] [Indexed: 10/21/2022]
Abstract
Sugarcane (Saccharum officinarum), a sugar crop commonly grown for sugar production all over the world, is susceptible to several insect pests attack in addition to bacterial, fungal and viral infections leading to substantial reductions in its yield. The complex genetic makeup and lack of resistant genes in genome of sugarcane have made the conventional breeding a difficult and challenging task for breeders. Using pesticides for control of the attacking insects can harm beneficial insects, human and other animals and the environment as well. As alternative and effective strategy for control of insect pests, genetic engineering has been applied for overexpression of cry proteins, vegetative insecticidal proteins (vip), lectins and proteinase inhibitors (PI). In addition, the latest biotechnological tools such as host-induced gene silencing (HIGS) and CRISPR/Cas9 can be employed for sustainable control of insect pests in sugarcane. In this review overexpression of the cry, vip, lectins and PI genes in transgenic sugarcane and their disease resistance potential is described.
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Affiliation(s)
- Aneela Iqbal
- Department of Biotechnology, Abdul Wali Khan University, Mardan, Pakistan
| | - Raham Sher Khan
- Department of Biotechnology, Abdul Wali Khan University, Mardan, Pakistan.
| | - Mubarak Ali Khan
- Department of Biotechnology, Abdul Wali Khan University, Mardan, Pakistan
| | - Karim Gul
- Department of Biotechnology, Abdul Wali Khan University, Mardan, Pakistan
| | - Fazal Jalil
- Department of Biotechnology, Abdul Wali Khan University, Mardan, Pakistan
| | - Daud Ali Shah
- Department of Biotechnology, Abdul Wali Khan University, Mardan, Pakistan
| | - Hazir Rahman
- Department of Microbiology, Abdul Wali Khan University, Mardan, Pakistan
| | - Talaat Ahmed
- Department of Biological and Environmental Sciences, College of Arts and Science, Qatar University, Doha, Qatar
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16
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Secaira-Morocho H, Castillo JA, Driks A. Diversity and evolutionary dynamics of spore-coat proteins in spore-forming species of Bacillales. Microb Genom 2020; 6. [PMID: 33052805 PMCID: PMC7725329 DOI: 10.1099/mgen.0.000451] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Among members of the Bacillales order, there are several species capable of forming a structure called an endospore. Endospores enable bacteria to survive under unfavourable growth conditions and germinate when environmental conditions are favourable again. Spore-coat proteins are found in a multilayered proteinaceous structure encasing the spore core and the cortex. They are involved in coat assembly, cortex synthesis and germination. Here, we aimed to determine the diversity and evolutionary processes that have influenced spore-coat genes in various spore-forming species of Bacillales using an in silico approach. For this, we used sequence similarity searching algorithms to determine the diversity of coat genes across 161 genomes of Bacillales. The results suggest that among Bacillales, there is a well-conserved core genome, composed mainly by morphogenetic coat proteins and spore-coat proteins involved in germination. However, some spore-coat proteins are taxa-specific. The best-conserved genes among different species may promote adaptation to changeable environmental conditions. Because most of the Bacillus species harbour complete or almost complete sets of spore-coat genes, we focused on this genus in greater depth. Phylogenetic reconstruction revealed eight monophyletic groups in the Bacillus genus, of which three are newly discovered. We estimated the selection pressures acting over spore-coat genes in these monophyletic groups using classical and modern approaches and detected horizontal gene transfer (HGT) events, which have been further confirmed by scanning the genomes to find traces of insertion sequences. Although most of the genes are under purifying selection, there are several cases with individual sites evolving under positive selection. Finally, the HGT results confirm that sporulation is an ancestral feature in Bacillus.
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Affiliation(s)
- Henry Secaira-Morocho
- School of Biological Sciences and Engineering, Yachay Tech University, San Miguel de Urcuquí, Imbabura, Ecuador
| | - José A Castillo
- School of Biological Sciences and Engineering, Yachay Tech University, San Miguel de Urcuquí, Imbabura, Ecuador
| | - Adam Driks
- Department of Microbiology and Immunology, Loyola University Chicago, Chicago, IL, USA
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17
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Brown AJ, Newhouse AE, Powell WA, Parry D. Comparative efficacy of gypsy moth (Lepidoptera: Erebidae) entomopathogens on transgenic blight-tolerant and wild-type American, Chinese, and hybrid chestnuts (Fagales: Fagaceae). INSECT SCIENCE 2020; 27:1067-1078. [PMID: 31339228 DOI: 10.1111/1744-7917.12713] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 06/04/2019] [Accepted: 06/26/2019] [Indexed: 06/10/2023]
Abstract
American chestnut (Castanea dentata [Marsh.] Borkh.) was once the dominant hardwood species in Eastern North America before an exotic fungal pathogen, Cryphonectria parasitica (Murrill) Barr, functionally eliminated it across its range. One promising approach toward restoring American chestnut to natural forests is development of blight-tolerant trees using genetic transformation. However, transformation and related processes can result in unexpected and unintended phenotypic changes, potentially altering ecological interactions. To assess unintended tritrophic impacts of transgenic American chestnut on plant-herbivore interactions, gypsy moth (Lymantria dispar L.) caterpillars were fed leaf disks excised from two transgenic events, Darling 54 and Darling 58, and four control American chestnut lines. Leaf disks were previously treated with an LD50 dose of either the species-specific Lymantria dispar multiple nucleopolyhedrovirus (LdMNPV) or the generalist pathogen Bacillus thuringiensis subsp. kurstaki (Btk). Mortality was quantified and compared to water blank controls. Tree genotype had a strong effect on the efficacies of both pathogens. Larval mortality from Btk-treated foliage from only one transgenic event, Darling 54, differed from its isogenic progenitor, Ellis 1, but was similar to an unrelated wild-type American chestnut control. LdMNPV efficacy was unaffected by genetic transformation. Results suggest that although genetic modification of trees may affect interactions with other nontarget organisms, this may be due to insertion effects, and variation among different genotypes (whether transgenic or wild-type) imparts a greater change in response than transgene presence.
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Affiliation(s)
- Aaron J Brown
- Department of Environmental and Forest Biology, College of Environmental Science and Forestry, State University of New York, Syracuse, NY, 13210, USA
| | - Andrew E Newhouse
- Department of Environmental and Forest Biology, College of Environmental Science and Forestry, State University of New York, Syracuse, NY, 13210, USA
| | - William A Powell
- Department of Environmental and Forest Biology, College of Environmental Science and Forestry, State University of New York, Syracuse, NY, 13210, USA
| | - Dylan Parry
- Department of Environmental and Forest Biology, College of Environmental Science and Forestry, State University of New York, Syracuse, NY, 13210, USA
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18
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Wang J, Ding MY, Wang J, Liu RM, Li HT, Gao JG. In silico Structure-Based Investigation of Key Residues of Insecticidal Activity of Sip1Aa Protein. Front Microbiol 2020; 11:984. [PMID: 32547509 PMCID: PMC7273025 DOI: 10.3389/fmicb.2020.00984] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 04/23/2020] [Indexed: 01/16/2023] Open
Abstract
Colaphellus bowringi Baly mainly damages cruciferous vegetables, leading to huge economic losses. The secretory insecticidal protein (Sip) of Bacillus thuringiensis (Bt) has high insecticidal activity against C. bowringi Baly. The tertiary structure of Sip1Aa protein was analyzed by homologous modeling and other bioinformatics methods to predict the conserved domain of Sip1Aa protein. Acidic and basic amino acids in the conserved domain were selected, and alanine was used to replace these amino acids by site-directed mutation. The difference between the insecticidal activities of mutant protein and Sip1Aa protein was analyzed. The insecticidal activities of H99A, K109A, K128A, and E130A against C. bowringi Baly were significantly increased, among which that of K128A was the most obviously changed, and the LC50 value was decreased by about 10 times compared with that of Sip1Aa protein. The LC50 value of mutant E130A was 0.286 μg/mL, which was about six times less than that of Sip1Aa. K128 and E130 were both in the β9–β10 loop. The toxicity of D290A, H242A, and H303A to C. bowringi Baly was significantly reduced, and their LC50 value increased by about six, eight, and three times compared with that of Sip1Aa protein, respectively. This study showed that acidic and basic amino acid residues played a certain role in the toxicity of Sip1Aa protein, and the loss of side chains in key residues had a significant impact on the insecticidal activity of the protein. This study provides the theoretical basis for revealing the relationship between the structure and function of Sip1Aa protein and also provides a new method for the subsequent study of sip gene.
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Affiliation(s)
- Jing Wang
- College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Ming-Yue Ding
- College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Jian Wang
- College of Life Sciences, Northeast Agricultural University, Harbin, China.,State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Rong-Mei Liu
- College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Hai-Tao Li
- College of Life Sciences, Northeast Agricultural University, Harbin, China.,State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Ji-Guo Gao
- College of Life Sciences, Northeast Agricultural University, Harbin, China
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19
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Gowelo S, Chirombo J, Spitzen J, Koenraadt CJM, Mzilahowa T, van den Berg H, Takken W, McCann R. Effects of larval exposure to sublethal doses of Bacillus thuringiensis var. israelensis on body size, oviposition and survival of adult Anopheles coluzzii mosquitoes. Parasit Vectors 2020; 13:259. [PMID: 32416733 PMCID: PMC7229702 DOI: 10.1186/s13071-020-04132-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 05/11/2020] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Application of the larvicide Bacillus thuringiensis var. israelensis (Bti) is a viable complementary strategy for malaria control. Efficacy of Bti is dose-dependent. There is a knowledge gap on the effects of larval exposure to sublethal Bti doses on emerging adult mosquitoes. The present study examined the effect of larval exposure to sublethal doses of Bti on the survival, body size and oviposition rate in adult Anopheles coluzzii. METHODS Third-instar An. coluzzii larvae were exposed to control and sublethal Bti concentrations at LC20, LC50 and LC70 for 48 h. Surviving larvae were reared to adults under standard colony conditions. Thirty randomly selected females from each treatment were placed in separate cages and allowed to blood feed. Twenty-five gravid females from the blood-feeding cages were randomly selected and transferred into new cages where they were provided with oviposition cups. Numbers of eggs laid in each cage and mortality of all adult mosquitoes were recorded daily. Wing lengths were measured of 570 mosquitoes as a proxy for body size. RESULTS Exposure to LC70Bti doses for 48 h as third-instar larvae reduced longevity of adult An. coluzzii mosquitoes. Time to death was 2.58 times shorter in females exposed to LC70Bti when compared to the control females. Estimated mortality hazard rates were also higher in females exposed to the LC50 and LC20 treatments, but these differences were not statistically significant. The females exposed to LC70 concentrations had 12% longer wings than the control group (P < 0.01). No differences in oviposition rate of the gravid females were observed between the treatments. CONCLUSIONS Exposure of An. coluzzii larvae to sublethal Bti doses reduces longevity of resultant adults and is associated with larger adult size and unclear effect on oviposition. These findings suggest that anopheline larval exposure to sublethal Bti doses, though not recommended, could reduce vectorial capacity for malaria vector populations by increasing mortality of resultant adults.
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Affiliation(s)
- Steven Gowelo
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- Training and Research Unit of Excellence, School of Public Health, College of Medicine, Blantyre, Malawi
| | - James Chirombo
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Jeroen Spitzen
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | | | | | - Henk van den Berg
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Robert McCann
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- Training and Research Unit of Excellence, School of Public Health, College of Medicine, Blantyre, Malawi
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, USA
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20
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Mahmood S, Kumar M, Kumari P, Mahapatro GK, Banerjee N, Sarin NB. Novel insecticidal chitinase from the insect pathogen Xenorhabdus nematophila. Int J Biol Macromol 2020; 159:394-401. [PMID: 32422264 DOI: 10.1016/j.ijbiomac.2020.05.078] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 04/18/2020] [Accepted: 05/04/2020] [Indexed: 12/28/2022]
Abstract
Xenorhabdus nematophila strain ATCC 19061 is an insect pathogen that produces various protein toxins which intoxicate and kill its larval host. In the present study, we have described the cloning, expression and characterization of a 76-kDa chitinase protein of X. nematophila. A 1.9 kb DNA sequence encoding the chitinase gene was PCR amplified and cloned. Further, the chitinase protein was expressed in Escherichia coli and purified by using affinity chromatography. Two highly conserved domains were identified GH18 and ChiA. The purified chitinase protein showed chitobiosidase activity, β-N-acetylglucosaminidase and endochitinase activity, when enzyme activity was measured using respective substrates. The purified chitinase protein was found to be orally toxic to the larvae of a major crop pest, Helicoverpa armigera when fed to the larvae mixed with artificial diet. It also had adverse effect on the growth and development of the surviving larvae. Surviving larvae showed 9-fold reduction in weight, as a result the transformation of larvae into pupae was adversely affected. Our results demonstrated that the chitinase protein of X. nematophila has insecticidal property and can prove to be a potent candidate for pest control in plants.
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Affiliation(s)
- Saquib Mahmood
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Mukesh Kumar
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Punam Kumari
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Gagan Kumar Mahapatro
- Division of Entomology, Indian Agricultural Research Institute, New Delhi 110012, India
| | - Nirupama Banerjee
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Neera Bhalla Sarin
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
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21
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Heini N, Stephan R, Filter M, Plaza-Rodriguez C, Frentzel H, Ehling-Schulz M, Johler S. Temperature-Dependent Growth Characteristics of Bacillus thuringiensis in a Ratatouille Food Model. J Food Prot 2020; 83:816-820. [PMID: 32318723 DOI: 10.4315/0362-028x.jfp-19-358] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 12/26/2019] [Indexed: 11/11/2022]
Abstract
ABSTRACT In contrast to Bacillus cereus, the role of Bacillus thuringiensis in foodborne illness has been controversially discussed. As B. thuringiensis-based biopesticides containing a mixture of crystal toxins and viable spores are widely used, a current European Food Safety Authority opinion underlines the need for additional data to enable risk assessment. However, it is currently poorly understood if B. thuringiensis is able to multiply in food, which is crucial to sound risk assessment. Therefore, the aim of this study was to investigate growth of selected B. thuringiensis strains from food and insecticides in a ratatouille food model. To this end, the growth parameters of three B. thuringiensis strains were determined: insecticide strain ABTS-351 (CH_119, B. thuringiensis serovar kurstaki), insecticide strain ABTS-1857 (CH_121, B. thuringiensis serovar aizawai), and CH_48 (wild-type B. thuringiensis isolated from rosemary), producing extremely high levels of enterotoxins. After an initial drop in colony counts, we observed a statistically significant growth for the tested B. thuringiensis strains between 6 and 24 h at 22, 30, and 37°C, conditions mimicking prolonged holding times. We were also able to show that the enterotoxin overproducer CH_48 can grow up to 108 CFU/g in the ratatouille matrix within 24 h at 37°C. The two midlevel enterotoxin formers ABTS-351 (CH_119) and ABTS-1857 (CH_121) isolated from biopesticides exhibited growth between 6 and 24 h, with one of the strains growing to 107 CFU/g. To our knowledge, this is the first study providing evidence of B. thuringiensis growth in a food model with intact competitive flora. Our findings suggest strain-specific variation and stress the complexity of assessing the risk related to B. thuringiensis in food, indicating that some strains can represent a risk to consumer health when vegetable-based foods are stored under conditions of prolonged temperature abuse. HIGHLIGHTS
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Affiliation(s)
- Nicole Heini
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland
| | - Roger Stephan
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland
| | - Matthias Filter
- German Federal Institute for Risk Assessment, Diedersdorfer Weg 1, 12277 Berlin, Germany; and
| | | | - Hendrik Frentzel
- German Federal Institute for Risk Assessment, Diedersdorfer Weg 1, 12277 Berlin, Germany; and
| | - Monika Ehling-Schulz
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - Sophia Johler
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland
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22
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Marques LH, Santos AC, Castro BA, Storer NP, Babcock JM, Lepping MD, Sa V, Moscardini VF, Rule DM, Fernandes OA. Impact of transgenic soybean expressing Cry1Ac and Cry1F proteins on the non-target arthropod community associated with soybean in Brazil. PLoS One 2018; 13:e0191567. [PMID: 29394266 PMCID: PMC5796694 DOI: 10.1371/journal.pone.0191567] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 01/08/2018] [Indexed: 11/20/2022] Open
Abstract
Field-scale studies that examine the potential for adverse effects of Bt crop technology on non-target arthropods may supplement data from laboratory studies to support an environmental risk assessment. A three year field study was conducted in Brazil to evaluate potential for adverse effects of cultivating soybean event DAS-81419-2 that produces the Cry1Ac and Cry1F proteins. To do so, we examined the diversity and abundance of non-target arthropods (NTAs) in Bt soybean in comparison with its non-Bt near isoline, with and without conventional insecticide applications, in three Brazilian soybean producing regions. Non-target arthropod abundance was surveyed using Moericke traps (yellow pan) and pitfall trapping. Total abundance (N), richness (S), Shannon-Wiener (H'), Simpson's (D) and Pielou's evenness (J) values for arthropod samples were calculated for each treatment and sampling period (soybean growth stages). A faunistic analysis was used to select the most representative NTAs which were used to describe the NTA community structure associated with soybean, and to test for effects due to the treatments effects via application of the Principal Response Curve (PRC) method. Across all years and sites, a total of 254,054 individuals from 190 taxa were collected by Moericke traps, while 29,813 individuals from 100 taxa were collected using pitfall traps. Across sites and sampling dates, the abundance and diversity measurements of representative NTAs were not significantly affected by Bt soybean as compared with non-sprayed non-Bt soybean. Similarly, community analyses and repeated measures ANOVA, when applicable, indicated that neither Bt soybean nor insecticide sprays altered the structure of the NTA communities under study. These results support the conclusion that transgenic soybean event DAS-81419-2 producing Cry1Ac and Cry1F toxins does not adversely affect the NTA community associated with soybean.
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Affiliation(s)
- Luiz H. Marques
- Dow AgroSciences Industrial Ltda, São Paulo, São Paulo, Brazil
| | | | - Boris A. Castro
- Dow AgroSciences LLC, Indianapolis, Indiana, United States of America
| | | | | | - Miles D. Lepping
- Dow AgroSciences LLC, Indianapolis, Indiana, United States of America
| | - Verissimo Sa
- Dow AgroSciences Industrial Ltda, São Paulo, São Paulo, Brazil
| | | | - Dwain M. Rule
- Dow AgroSciences LLC, Indianapolis, Indiana, United States of America
| | - Odair A. Fernandes
- Universidade Estadual Paulista (FCAV/UNESP), Faculdade de Ciências Agrárias e Veterinárias, FCAV/UNESP, Jaboticabal, São Paulo, Brazil
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23
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Porcellato D, Aspholm M, Skeie SB, Mellegård H. Application of a novel amplicon-based sequencing approach reveals the diversity of the Bacillus cereus group in stored raw and pasteurized milk. Food Microbiol 2018; 81:32-39. [PMID: 30910086 DOI: 10.1016/j.fm.2018.01.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 12/20/2017] [Accepted: 01/15/2018] [Indexed: 12/16/2022]
Abstract
Members of the Bacillus cereus sensu lato (B. cereus group) are spore-forming organisms commonly associated with spoilage of milk and dairy products. Previous studies have shown, by using 16S marker gene sequencing, that the genus Bacillus is part of the core microbiota of raw bovine milk and that some members of this genus are able to grow during sub-optimal storage (8 °C) of pasteurized consumption milk. Here, the composition of this genus in pasteurized consumption milk samples, collected from two dairies, over a one-year period and stored at 4 or 8 °C up to the end of shelf life is uncovered. Our results show that the B. cereus group is the dominant Bacillus group in stored consumption milk. By applying a new marker gene sequencing approach, several dominating phylogenetic clusters were identified within the B. cereus group populations from the milk samples. There was a higher phylogenetic diversity among bacteria from milk stored at 8 °C compared to milk stored at 4 °C. Sampling period and the dairy the samples were collected from, also significantly influenced the diversity, which shows that the B. cereus group population in consumption milk is heterogeneous and subjected to temporal and spatial changes. The new approach applied in this study will facilitate the identification of isolates within the B. cereus group, of which some are potential spoilage bacteria and pathogenic contaminants of milk and dairy products.
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Affiliation(s)
- Davide Porcellato
- Faculty of Chemistry, Biotechnology and Food Science, The Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Ås, Norway.
| | - Marina Aspholm
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, The Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Ås, Norway
| | - Siv Borghild Skeie
- Faculty of Chemistry, Biotechnology and Food Science, The Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Ås, Norway
| | - Hilde Mellegård
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, The Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Ås, Norway
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24
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Fortea E, Lemieux V, Potvin L, Chikwana V, Griffin S, Hey T, McCaskill D, Narva K, Tan SY, Xu X, Vachon V, Schwartz JL. Cry6Aa1, a Bacillus thuringiensis nematocidal and insecticidal toxin, forms pores in planar lipid bilayers at extremely low concentrations and without the need of proteolytic processing. J Biol Chem 2017. [PMID: 28623231 DOI: 10.1074/jbc.m116.765941] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cry6Aa1 is a Bacillus thuringiensis (Bt) toxin active against nematodes and corn rootworm insects. Its 3D molecular structure, which has been recently elucidated, is unique among those known for other Bt toxins. Typical three-domain Bt toxins permeabilize receptor-free planar lipid bilayers (PLBs) by forming pores at doses in the 1-50 μg/ml range. Solubilization and proteolytic activation are necessary steps for PLB permeabilization. In contrast to other Bt toxins, Cry6Aa1 formed pores in receptor-free bilayers at doses as low as 200 pg/ml in a wide range of pH (5.5-9.5) and without the need of protease treatment. When Cry6Aa1 was preincubated with Western corn rootworm (WCRW) midgut juice or trypsin, 100 fg/ml of the toxin was sufficient to form pores in PLBs. The overall biophysical properties of the pores were similar for all three forms of the toxin (native, midgut juice- and trypsin-treated), with conductances ranging from 28 to 689 pS, except for their ionic selectivity, which was slightly cationic for the native and midgut juice-treated Cry6Aa1, whereas dual selectivity (to cations or anions) was observed for the pores formed by the trypsin-treated toxin. Enrichment of PLBs with WCRW midgut brush-border membrane material resulted in a 2000-fold reduction of the amount of native Cry6Aa1 required to form pores and affected the biophysical properties of both the native and trypsin-treated forms of the toxin. These results indicate that, although Cry6Aa1 forms pores, the molecular determinants of its mode of action are significantly different from those reported for other Bt toxins.
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Affiliation(s)
- Eva Fortea
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | - Vincent Lemieux
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada.,the Département de biologie, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - Léna Potvin
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | | | | | - Timothy Hey
- Dow AgroSciences LLC, Indianapolis, Indiana 46268, and
| | | | - Kenneth Narva
- Dow AgroSciences LLC, Indianapolis, Indiana 46268, and
| | - Sek Yee Tan
- Dow AgroSciences LLC, Indianapolis, Indiana 46268, and
| | - Xiaoping Xu
- Dow AgroSciences LLC, Indianapolis, Indiana 46268, and
| | - Vincent Vachon
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | - Jean-Louis Schwartz
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada, .,the Centre SÈVE de recherche en sciences du végétal, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1 Canada
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25
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Kabir MS, Hsieh YH, Simpson S, Kerdahi K, Sulaiman IM. Evaluation of Two Standard and Two Chromogenic Selective Media for Optimal Growth and Enumeration of Isolates of 16 Unique Bacillus Species. J Food Prot 2017; 80:952-962. [PMID: 28467187 DOI: 10.4315/0362-028x.jfp-16-441] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The genus Bacillus is a group of gram-positive endospore-forming bacteria that can cause food poisoning and diarrheal illness in humans. A wide range of food products have been linked to foodborne outbreaks associated with these opportunistic pathogens. The U.S. Food and Drug Administration recommends (in their Bacteriological Analytical Manual) the use of Bacara or mannitol egg yolk polymyxin (MYP) agar plates and the most-probable-number (MPN) method for enumeration and confirmation of Bacillus cereus and related species isolated from foods, sporadic cases, outbreaks, and routine environmental surveillance samples. We performed a comparative analysis of two chromogenic media (Bacara and Brilliance) and two traditional media (MYP and polymyxin egg yolk mannitol bromothymol blue agar [PEMBA]) for the isolation and enumeration of 16 Bacillus species under modified growth conditions that included pH, temperature, and dilution factor. A total of 50 environmental, food, and American Type Culture Collection reference isolates from 16 distinct Bacillus species were evaluated. A food adulteration experiment also was carried out by artificially adulterating two baby food matrices with two isolates each of B. cereus and Bacillus thuringiensis . Our results clearly indicated that chromogenic plating media (Bacara and Brilliance) are better than conventional standard media (MYP and PEMBA) for the detection and enumeration of B. cereus in foods and other official regulatory samples. The comparison of the two chromogenic media also indicated that Brilliance medium to be more efficient and selective for the isolation of Bacillus.
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Affiliation(s)
- M Shahjahan Kabir
- U.S. Food and Drug Administration, Southeast Regional Laboratory, 60 Eight Street, Atlanta, Georgia 30309, USA
| | - Ying-Hsin Hsieh
- U.S. Food and Drug Administration, Southeast Regional Laboratory, 60 Eight Street, Atlanta, Georgia 30309, USA
| | - Steven Simpson
- U.S. Food and Drug Administration, Southeast Regional Laboratory, 60 Eight Street, Atlanta, Georgia 30309, USA
| | - Khalil Kerdahi
- U.S. Food and Drug Administration, Southeast Regional Laboratory, 60 Eight Street, Atlanta, Georgia 30309, USA
| | - Irshad M Sulaiman
- U.S. Food and Drug Administration, Southeast Regional Laboratory, 60 Eight Street, Atlanta, Georgia 30309, USA
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26
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Wang G, Chen H, Wang X, Peng L, Peng Y, Li YQ. Probing the germination kinetics of ethanol-treated Bacillus thuringiensis spores. APPLIED OPTICS 2017; 56:3263-3269. [PMID: 28430241 DOI: 10.1364/ao.56.003263] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Bacillus thuringiensis (Bt) is the most widely used microbial insecticide. To clarify the mechanism of bacterial resistance to ethanol toxicity, the present study investigated the effects of 70% (v/v) ethanol at a moderate temperature (65°C) on Bt spore germination by single-cell Raman spectroscopy and differential interference contrast microscopy. We found that over 80% of Bt spores were inviable after 30 min of treatment. Moreover, ethanol treatment affected spore germination; the time for initiation of rapid calcium dipicolinate (CaDPA) release (i.e., lag time, Tlag), time taken for rapid CaDPA release (i.e., ΔTrelease), and time required for complete hydrolysis of the peptidoglycan cortex of spores (i.e., ΔTlys) were increased with longer treatment times. Alanine-initiated germination upon ethanol treatment for 30-90 min showed a 2- to 4-fold longer Tlag, 2- to 3.5-fold longer ΔTrelease, and ∼2-fold longer ΔTlys relative to the control. Dodecylamine-initiated germination treated for 15-30 min had 3- to 5-fold longer Tlag and 1.4- to 1.7-fold longer ΔTrelease than the control. Germination induced by exogenous CaDPA was observed only in a small fraction of spores treated with ethanol for 5 min. Single-cell Raman spectroscopy revealed that more than 52% of spores lost CaDPA after 30 min of ethanol treatment; these showed reductions in the intensity of 1280 and 1652 cm-1 bands (corresponding to protein α-helical structure) and increases in that of 1245 and 1665 cm-1 bands (attributed to irregularities in protein structure). These results indicate that CaDPA in the core of Bt spores confers resistance to ethanol, and that damage to the spore inner membrane by ethanol treatment results in CaDPA leakage. Additionally, moderate-temperature ethanol treatment and consequent denaturation of germination-related proteins affected spore germination, specifically by inactivating the cortex-lytic enzyme CwlJ. Our findings provide a theoretical basis for the development of more effective methods for killing spore-forming bacteria; microscopy imaging and Raman spectroscopy can provide novel insight into the effects of chemical agents on microbial cells.
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27
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Wang LY, Gu SH, Nangong ZY, Song P, Wang QY. Aminopeptidase N5 (APN5) as a Putative Functional Receptor of Cry1Ac Toxin in the Larvae of Athetis lepigone. Curr Microbiol 2017; 74:455-459. [PMID: 28224224 DOI: 10.1007/s00284-017-1215-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 02/10/2017] [Indexed: 10/20/2022]
Abstract
Athetis lepigone was a new lepidopteran pest and caused severe damage to maize crops in China. We have detected that Cry1Ac protoxin and toxin were highly active against the larvae of A. lepigone. However, there is no report about the mode of action of Bt Cry1Ac toxin against this pest until now. A 110 kDa APN5 protein from BBMV of A. lepigone was identified as the binding receptor of Cry1Ac toxin using Ligand blotting. The Cry1Ac receptor APN5 was cloned from A. lepigone larval midgut mRNA and named as AlAPN5 (GenBank accession no.: KU950745). AlAPN5 had a GATEN motif and been classified to Class 5 APNs. 79.2% reduction in mortality was observed when A. lepigone larvae were injected with siRNA of the AlAPN5 gene and treated with Cry1Ac toxin. These data demonstrate that AlAPN5 is a putative functional receptor and maybe the only receptor of Cry1Ac in A. lepigone.
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Affiliation(s)
- Li-Yu Wang
- College of Plant Protection, Agricultural University of Hebei, Baoding, 071000, Hebei, People's Republic of China
| | - Shao-Hua Gu
- Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, People's Republic of China
| | - Zi-Yan Nangong
- College of Plant Protection, Agricultural University of Hebei, Baoding, 071000, Hebei, People's Republic of China
| | - Ping Song
- College of Plant Protection, Agricultural University of Hebei, Baoding, 071000, Hebei, People's Republic of China.
| | - Qin-Ying Wang
- College of Plant Protection, Agricultural University of Hebei, Baoding, 071000, Hebei, People's Republic of China
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28
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Yinghua S, Yan D, Jin C, Jiaxi W, Jianwu W. Responses of the cutworm Spodoptera litura (Lepidoptera: Noctuidae) to two Bt corn hybrids expressing Cry1Ab. Sci Rep 2017; 7:41577. [PMID: 28186125 PMCID: PMC5301207 DOI: 10.1038/srep41577] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 12/21/2016] [Indexed: 11/09/2022] Open
Abstract
To examine the responses of the secondary lepidopteran pest Spodoptera litura to two Bacillus thuringiensis (Bt) corn hybrids [5422Bt1 (Event Bt11), 5422CBCL (MON810)] expressing Cry1Ab, larval bioassays with Cry1Ab toxin, corn leaves or kernels and bagging on corn plants were conducted. The results showed that larvae displayed a similar performance when fed kernels, but not leaves of 5422Bt1, 5422CBCL and their near-isogenic non-Bt corn (5422). Significantly higher Cry1Ab amounts were detected in larvae fed leaves than kernels of both Bt hybrids, with different molecular weights of protein band in plants (72 and 90 kDa for 5422Bt1 and 5422CBCL, respectively), gut contents (65 kDa), feces (50 kDa), which indicated that larvae had lower ingestion, higher degradation and excretion of Cry1Ab when fed kernels not leaves of both Bt hybrids. Significantly higher levels of cadherin-like receptors and alkaline phosphatase transcripts were detected in larvae fed leaves than kernels of two Bt hybrids. Catalase, superoxide dismutase and glutathione-S-transferase activities in larvae fed 5422Bt1 leaves were significantly higher than that of 5422 treatments. Therefore, S. litura had low susceptibility to 5422Bt1 and 5422CBCL when larvae fed kernels not leaves of Bt corn. Additionally, S. litura presented a much stronger tolerance to 5422CBCL than 5422Bt1.
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Affiliation(s)
- Shu Yinghua
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China.,Key Laboratory of Agroecology and Rural Environment of Guangdong Regular Higher Education Institutions, South China Agricultural University, Guangzhou 510642, China.,Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.,Department of Crop Science and Technology, College of Agriculture, South China Agricultural University, Guangzhou 510642, China
| | - Du Yan
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China.,Key Laboratory of Agroecology and Rural Environment of Guangdong Regular Higher Education Institutions, South China Agricultural University, Guangzhou 510642, China.,Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
| | - Chen Jin
- Department of Crop Science and Technology, College of Agriculture, South China Agricultural University, Guangzhou 510642, China
| | - Wei Jiaxi
- Department of Crop Science and Technology, College of Agriculture, South China Agricultural University, Guangzhou 510642, China
| | - Wang Jianwu
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China.,Key Laboratory of Agroecology and Rural Environment of Guangdong Regular Higher Education Institutions, South China Agricultural University, Guangzhou 510642, China.,Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
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29
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Regode V, Kuruba S, Mohammad AS, Sharma HC. Isolation and Characterization of Gut Bacterial Proteases Involved in Inducing Pathogenicity of Bacillus thuringiensis Toxin in Cotton Bollworm, Helicoverpa armigera. Front Microbiol 2016; 7:1567. [PMID: 27766093 PMCID: PMC5052264 DOI: 10.3389/fmicb.2016.01567] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 09/20/2016] [Indexed: 12/16/2022] Open
Abstract
Bacillus thuringiensis toxin proteins are deployed in transgenic plants for pest management. The present studies were aimed at characterization of gut bacterial proteases involved in activation of inactive Cry1Ac protoxin (pro-Cry1Ac) to active toxin in Helicoverpa armigera. Bacterial strains were isolated from H. armigera midgut and screened for their proteolytic activation toward pro-Cry1Ac. Among 12 gut bacterial isolates seven isolates showed proteolytic activity, and proteases from three isolates (IVS1, IVS2, and IVS3) were found to be involved in the proteolytic conversion of pro-Cry1Ac into active toxin. The proteases from IVS1, IVS2, and IVS3 isolates were purified to 11.90-, 15.50-, and 17.20-fold, respectively. The optimum pH and temperature for gut bacterial protease activity was 8.0 and 40°C. Maximum inhibition of total proteolytic activity was exerted by phenylmethane sulfonyl fluoride followed by EDTA. Fluorescence zymography revealed that proteases from IVS1, IVS2, and IVS3 were chymotrypsin-like and showing protease band at ~15, 65, and 15 kDa, respectively. Active Cry1Ac formed from processing pro-Cry1Ac by gut bacterial proteases exhibited toxicity toward H. armigera. The gut bacterial isolates IVS1, IVS2, and IVS3 showed homology with B. thuringiensis (CP003763.1), Vibrio fischeri (CP000020.2), and Escherichia coli (CP011342.1), respectively. Proteases produced by midgut bacteria are involved in proteolytic processing of B. thuringiensis protoxin and play a major role in inducing pathogenicity of B. thuringiensis toxins in H. armigera.
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Affiliation(s)
- Visweshwar Regode
- Department of Entomology, International Crops Research Institute for the Semi-Arid Tropics, PatancheruIndia; Department of Biochemistry, Gulbarga University, KalaburagiIndia
| | | | - Akbar S Mohammad
- Department of Entomology, International Crops Research Institute for the Semi-Arid Tropics, Patancheru India
| | - Hari C Sharma
- Department of Entomology, International Crops Research Institute for the Semi-Arid Tropics, Patancheru India
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30
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Joshi SS, Barnett B, Doerrer NG, Glenn K, Herman RA, Herouet-Guicheney C, Hunst P, Kough J, Ladics GS, McClain S, Papineni S, Poulsen LK, Rascle JB, Tao AL, van Ree R, Ward J, Bowman CC. Assessment of potential adjuvanticity of Cry proteins. Regul Toxicol Pharmacol 2016; 79:149-155. [PMID: 27105772 DOI: 10.1016/j.yrtph.2016.04.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 04/13/2016] [Indexed: 10/21/2022]
Abstract
Genetically modified (GM) crops have achieved success in the marketplace and their benefits extend beyond the overall increase in harvest yields to include lowered use of insecticides and decreased carbon dioxide emissions. The most widely grown GM crops contain gene/s for targeted insect protection, herbicide tolerance, or both. Plant expression of Bacillus thuringiensis (Bt) crystal (Cry) insecticidal proteins have been the primary way to impart insect resistance in GM crops. Although deemed safe by regulatory agencies globally, previous studies have been the basis for discussions around the potential immuno-adjuvant effects of Cry proteins. These studies had limitations in study design. The studies used animal models with extremely high doses of Cry proteins, which when given using the ig route were co-administered with an adjuvant. Although the presumption exists that Cry proteins may have immunostimulatory activity and therefore an adjuvanticity risk, the evidence shows that Cry proteins are expressed at very low levels in GM crops and are unlikely to function as adjuvants. This conclusion is based on critical review of the published literature on the effects of immunomodulation by Cry proteins, the history of safe use of Cry proteins in foods, safety of the Bt donor organisms, and pre-market weight-of-evidence-based safety assessments for GM crops.
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Affiliation(s)
- Saurabh S Joshi
- Monsanto Company, 800 North Lindbergh Blvd., St. Louis, MO 63167, USA.
| | - Brian Barnett
- BASF Plant Science, 26 Davis Drive, Research Triangle Park, NC 27709, USA.
| | - Nancy G Doerrer
- ILSI Health and Environmental Sciences Institute, 1156 Fifteenth St., NW, Suite 200, Washington, DC 20005, USA.
| | - Kevin Glenn
- Monsanto Company, 800 North Lindbergh Blvd., St. Louis, MO 63167, USA.
| | - Rod A Herman
- Dow AgroSciences, 9330 Zionsville Rd, Indianapolis, IN 46268, USA.
| | | | - Penny Hunst
- Bayer CropScience, 2 T.W. Alexander Dr., Research Triangle Park, NC 27709, USA.
| | - John Kough
- U.S. Environmental Protection Agency, Office of Pesticide Programs, Ariel Rios Building, MC 7511P, 1200 Pennsylvania Avenue, NW, Washington, DC 20460, USA.
| | - Gregory S Ladics
- DuPont Haskell Global Centers for Health and Environmental Sciences, 1090 Elkton Road, Newark, DE 19711, USA.
| | - Scott McClain
- Syngenta Crop Protection, LLC, 3054 E. Cornwallis Road, Research Triangle Park, NC 27709, USA.
| | - Sabitha Papineni
- Dow AgroSciences, 9330 Zionsville Rd, Indianapolis, IN 46268, USA.
| | - Lars K Poulsen
- Allergy Clinic, Copenhagen University Hospital at Gentofte, Niels Andersens Vej 65, Dept. 22, 1st Floor, DK-2900 Hellerup, Denmark.
| | - Jean-Baptiste Rascle
- Bayer SAS, Bayer CropScience, 355 Rue Dostoïevski, 06903 Sophia Antipolis Cedex, France.
| | - Ai-Lin Tao
- Guangzhou Medical University, 250 Changgang Road East, Guangzhou 510260, People's Republic of China.
| | - Ronald van Ree
- Departments of Experimental Immunology and Otorhinolaryngology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, Room K0-130, 1105 AZ Amsterdam, The Netherlands.
| | - Jason Ward
- Monsanto Company, 800 North Lindbergh Blvd., St. Louis, MO 63167, USA.
| | - Christal C Bowman
- Bayer CropScience, 2 T.W. Alexander Dr., Research Triangle Park, NC 27709, USA.
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31
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Dammak M, Khedher SB, Boukedi H, Chaib I, Laarif A, Tounsi S. Involvement of the processing step in the susceptibility/tolerance of two lepidopteran larvae to Bacillus thuringiensis Cry1Aa toxin. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2016; 127:46-50. [PMID: 26821657 DOI: 10.1016/j.pestbp.2015.09.005] [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: 03/14/2015] [Revised: 09/13/2015] [Accepted: 09/15/2015] [Indexed: 06/05/2023]
Abstract
Bacillus thuringiensis (Bt) Cry1A toxins are known for their effectiveness against lepidopteran insects. In this study, the entomopathogenic activity of Cry1Aa was investigated against two lepidopteran larvae causing serious threat to various crops, Spodoptera littoralis and Tuta absoluta. Contrarily to S. littoralis, which showed low susceptibility to Cry1Aa (40% mortality with 1μg/cm(2)), T. absoluta was very sensitive to this delta-endotoxin (LC50 of 95.8ng/cm(2)). The different steps in the mode of action of this toxin on the two larvae were studied with the aim to understand the origin of their difference of susceptibility. Activation of the 130kDa Cry1Aa protein by T. absoluta larvae juice generated a 65kDa active toxin, whereas S. littoralis gut juice led to a complete degradation of the protoxin. The study of the interaction of the brush border membrane vesicles (BBMV) with purified biotinylated Cry1Aa toxin revealed six and seven toxin binding proteins in T. absoluta and S. littoralis BBMV, respectively. Midgut histopathology of Cry1Aa fed larvae demonstrated approximately similar damage caused by the toxin in the two larvae midguts. These results suggest that the activation step was strongly involved in the difference of susceptibility of the two larvae to Cry1Aa.
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Affiliation(s)
- Mariam Dammak
- Team of Biopesticides (LPIP), Centre of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, 3018 Sfax, Tunisia.
| | - Saoussen Ben Khedher
- Team of Biopesticides (LPIP), Centre of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, 3018 Sfax, Tunisia
| | - Hanen Boukedi
- Team of Biopesticides (LPIP), Centre of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, 3018 Sfax, Tunisia
| | - Ikbel Chaib
- Unit of Entomology (UR13A-GR09), Regional Research Center on Horticulture and Organic Agriculture, University of Sousse, Chott-Mariem, 4042, Tunisia
| | - Asma Laarif
- Unit of Entomology (UR13A-GR09), Regional Research Center on Horticulture and Organic Agriculture, University of Sousse, Chott-Mariem, 4042, Tunisia
| | - Slim Tounsi
- Team of Biopesticides (LPIP), Centre of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, 3018 Sfax, Tunisia
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32
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Rubio-Infante N, Moreno-Fierros L. An overview of the safety and biological effects of Bacillus thuringiensis Cry toxins in mammals. J Appl Toxicol 2015; 36:630-48. [PMID: 26537666 DOI: 10.1002/jat.3252] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Revised: 09/08/2015] [Accepted: 09/09/2015] [Indexed: 12/12/2022]
Abstract
Crystal proteins (Cry) produced during the growth and sporulation phases of Bacillus thuringiensis (Bt) bacterium are known as delta endotoxins. These toxins are being used worldwide as bioinsecticides to control pests in agriculture, and some Cry toxins are used against mosquitoes to control vector transmission. This review summarizes the relevant information currently available regarding the biosafety and biological effects that Bt and its insecticidal Cry proteins elicit in mammals. This work was performed because of concerns regarding the possible health impact of Cry toxins on vertebrates, particularly because Bt toxins might be associated with immune-activating or allergic responses. The controversial data published to date are discussed in this review considering earlier toxicological studies of B. thuringiensis, spores, toxins and Bt crops. We discussed the experimental studies performed in humans, mice, rats and sheep as well as in diverse mammalian cell lines. Although the term 'toxic' is not appropriate for defining the effects these toxins have on mammals, they cannot be considered innocuous, as they have some physiological effects that may become pathological; thus, trials that are more comprehensive are necessary to determine their effects on mammals because knowledge in this field remains limited.
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Affiliation(s)
- Néstor Rubio-Infante
- Laboratorio de Inmunidad en Mucosas, Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios 1, Los Reyes Iztacala, Tlalnepantla, 54090, Estado de México, México
| | - Leticia Moreno-Fierros
- Laboratorio de Inmunidad en Mucosas, Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios 1, Los Reyes Iztacala, Tlalnepantla, 54090, Estado de México, México
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Mansour SA, Aly AR. Insecticidal Activity of Plant Oils, Bacterial Endotoxins and their Combinations againstMusca domesticaL. ACTA ACUST UNITED AC 2015. [DOI: 10.1080/22311866.2015.1015609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Fast BJ, Schafer AC, Johnson TY, Potts BL, Herman RA. Insect-protected event DAS-81419-2 soybean (Glycine max L.) grown in the United States and Brazil is compositionally equivalent to nontransgenic soybean. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:2063-73. [PMID: 25641393 PMCID: PMC4342727 DOI: 10.1021/jf505015y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 01/28/2015] [Accepted: 01/31/2015] [Indexed: 05/12/2023]
Abstract
The transgenic soybean event DAS-81419-2 contains genes that encode the Cry1F, Cry1Ac, and PAT proteins. Cry1F and Cry1Ac provide protection against key lepidopteran insect pests, while PAT confers tolerance to the herbicide glufosinate. To satisfy regulatory requirements for the safety evaluation of transgenic crops, studies were conducted in the United States and Brazil to evaluate the nutrient and antinutrient composition of event DAS-81419-2 soybean. On the basis of the results of these studies, event DAS-81419-2 soybean is compositionally equivalent to nontransgenic soybean. This conclusion concurs with numerous other published studies in soybean and other crops where compositional equivalence between the transgenic crop and its nontransgenic comparator has been demonstrated.
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Affiliation(s)
- Brandon J. Fast
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States
| | - Ariane C. Schafer
- Dow AgroSciences Industrial Ltda., Rod. Anhanguera Km 296, Cravinhos, SP 14140-000, Brazil
| | - Tempest Y. Johnson
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States
| | - Brian L. Potts
- Covance
Laboratories Inc., 3301
Kinsman Boulevard, Madison, Wisconsin 53704, United States
| | - Rod A. Herman
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States
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Li M, Zhu M, Zhang C, Liu X, Wan Y. Uniform orientation of biotinylated nanobody as an affinity binder for detection of Bacillus thuringiensis (Bt) Cry1Ac toxin. Toxins (Basel) 2014; 6:3208-22. [PMID: 25474492 PMCID: PMC4280530 DOI: 10.3390/toxins6123208] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 11/10/2014] [Accepted: 11/17/2014] [Indexed: 12/26/2022] Open
Abstract
Nanobodies are the smallest natural fragments with useful properties such as high affinity, distinct paratope and high stability, which make them an ideal tool for detecting target antigens. In this study, we generated and characterized nanobodies against the Cry1Ac toxin and applied them in a biotin-streptavidin based double antibodies (nanobodies) sandwich-ELISA (DAS-ELISA) assay. After immunizing a camel with soluble Cry1Ac toxin, a phage displayed library was constructed to generate Nbs against the Cry1Ac toxin. Through successive rounds of affinity bio-panning, four nanobodies with greatest diversity in CDR3 sequences were obtained. After affinity determination and conjugating to HRP, two nanobodies with high affinity which can recognize different epitopes of the same antigen (Cry1Ac) were selected as capture antibody (Nb61) and detection antibody (Nb44). The capture antibody (Nb61) was biotinylated in vivo for directional immobilization on wells coated with streptavidin matrix. Both results of specificity analysis and thermal stability determination add support for reliability of the following DAS-ELISA with a minimum detection limit of 0.005 μg·mL-1 and a working range 0.010-1.0 μg·mL-1. The linear curve displayed an acceptable correlation coefficient of 0.9976. These results indicated promising applications of nanobodies for detection of Cry1Ac toxin with biotin-streptavidin based DAS-ELISA system.
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Affiliation(s)
- Min Li
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Sipailou NO. 2, Southeast University, Nanjing 210096, China.
| | - Min Zhu
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Sipailou NO. 2, Southeast University, Nanjing 210096, China.
| | - Cunzheng Zhang
- Institute of Food Safety, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
| | - Xianjin Liu
- Institute of Food Safety, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
| | - Yakun Wan
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Sipailou NO. 2, Southeast University, Nanjing 210096, China.
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Linn MD, Moore PA. The effects of bt corn on rusty crayfish (Orconectes rusticus) growth and survival. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2014; 67:436-443. [PMID: 25001246 DOI: 10.1007/s00244-014-0061-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 06/10/2014] [Indexed: 06/03/2023]
Abstract
Bt crops are one of the most commonly used genetically modified crops worldwide. Bt crops contain a gene that is derived from the bacteria Bacillus thuringiensis, which produces the Cry1Ab toxin. Bt corn that contains the Cry1Ab toxin is used throughout the Midwest United States to control crop pests such as the European corn borer (Ostrinia nubilalis). Headwater streams in regions known for intensive agriculture receive Bt corn detritus after the fall harvest, which is then consumed by a diverse community of stream invertebrates. The rusty crayfish (Orconectes rusticus) is a common invertebrate detritivore in these headwater streams. Both isogenic and Bt corn were grown under the controlled environmental conditions of a greenhouse and, after senescence, were tested for nutritional equality. Rusty crayfish were exposed to one of several detrital treatments composed of Bt corn, Bt corn plus American sycamore (Platanus occidentalis), isogenic corn alone, isogenic corn plus P. occidentalis, or P. occidentalis alone for 8 weeks. Both strains of corn were grown under the controlled environmental conditions in a greenhouse and were tested for nutritional equality after senescence. Crayfish were housed in live streams with a water temperature of 12.8 °C and a 12:12 h light-to-dark photoperiod. Survival and growth of animals within each experimental treatment were monitored each week. After 8 weeks of exposure, there was no statistically significant difference in growth between crayfish in Bt and isogenic treatments. However, survivorship was 31 % lower in the Bt treatment compared with the isogenic treatment. These results suggest that the Bt corn and isogenic corn were of equivalent nutritional value but that Bt corn does have a toxic effect on rusty crayfish during long-term exposure.
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Affiliation(s)
- Matthew D Linn
- Laboratory for Sensory Ecology, Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, 43403, USA,
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Ben Khedher S, Jaoua S, Zouari N. Overcome of Carbon Catabolite Repression of Bioinsecticides Production by Sporeless Bacillus thuringiensis through Adequate Fermentation Technology. BIOTECHNOLOGY RESEARCH INTERNATIONAL 2014; 2014:698587. [PMID: 25309756 PMCID: PMC4182890 DOI: 10.1155/2014/698587] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 07/03/2014] [Accepted: 09/03/2014] [Indexed: 11/18/2022]
Abstract
The overcoming of catabolite repression, in bioinsecticides production by sporeless Bacillus thuringiensis strain S22 was investigated into fully controlled 3 L fermenter, using glucose based medium. When applying adequate oxygen profile throughout the fermentation period (75% oxygen saturation), it was possible to partially overcome the catabolite repression, normally occurring at high initial glucose concentrations (30 and 40 g/L glucose). Moreover, toxin production yield by sporeless strain S22 was markedly improved by the adoption of the fed-batch intermittent cultures technology. With 22.5 g/L glucose used into culture medium, toxin production was improved by about 36% when applying fed-batch culture compared to one batch. Consequently, the proposed fed-batch strategy was efficient for the overcome of the carbon catabolite repression. So, it was possible to overproduce insecticidal crystal proteins into highly concentrated medium.
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Affiliation(s)
- Saoussen Ben Khedher
- Team of Biopesticides (LPIP), Centre of Biotechnology of Sfax, Sfax University, 3018 Sfax, Tunisia
| | - Samir Jaoua
- Department of Biological & Environmental Sciences, College of Arts and Sciences, Qatar University, P.O. Box 2713, Doha, Qatar
| | - Nabil Zouari
- Department of Biological & Environmental Sciences, College of Arts and Sciences, Qatar University, P.O. Box 2713, Doha, Qatar
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Lucena WA, Pelegrini PB, Martins-de-Sa D, Fonseca FCA, Gomes JE, de Macedo LLP, da Silva MCM, Oliveira RS, Grossi-de-Sa MF. Molecular approaches to improve the insecticidal activity of Bacillus thuringiensis Cry toxins. Toxins (Basel) 2014; 6:2393-423. [PMID: 25123558 PMCID: PMC4147589 DOI: 10.3390/toxins6082393] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 06/23/2014] [Accepted: 06/27/2014] [Indexed: 02/01/2023] Open
Abstract
Bacillus thuringiensis (Bt) is a gram-positive spore-forming soil bacterium that is distributed worldwide. Originally recognized as a pathogen of the silkworm, several strains were found on epizootic events in insect pests. In the 1960s, Bt began to be successfully used to control insect pests in agriculture, particularly because of its specificity, which reflects directly on their lack of cytotoxicity to human health, non-target organisms and the environment. Since the introduction of transgenic plants expressing Bt genes in the mid-1980s, numerous methodologies have been used to search for and improve toxins derived from native Bt strains. These improvements directly influence the increase in productivity and the decreased use of chemical insecticides on Bt-crops. Recently, DNA shuffling and in silico evaluations are emerging as promising tools for the development and exploration of mutant Bt toxins with enhanced activity against target insect pests. In this report, we describe natural and in vitro evolution of Cry toxins, as well as their relevance in the mechanism of action for insect control. Moreover, the use of DNA shuffling to improve two Bt toxins will be discussed together with in silico analyses of the generated mutations to evaluate their potential effect on protein structure and cytotoxicity.
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Affiliation(s)
- Wagner A. Lucena
- Embrapa Cotton, Campina Grande, 58428-095, PB, Brazil; E-Mail:
- Graduate Program in Cellular and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, 91501-970, RS, Brazil
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
| | - Patrícia B. Pelegrini
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
| | - Diogo Martins-de-Sa
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Department of Molecular Biology, Federal University of Brasília, Brasília, 70910-900, DF, Brazil
| | - Fernando C. A. Fonseca
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Department of Molecular Biology, Federal University of Brasília, Brasília, 70910-900, DF, Brazil
| | - Jose E. Gomes
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Department of Molecular Biology, Federal University of Brasília, Brasília, 70910-900, DF, Brazil
| | - Leonardo L. P. de Macedo
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Post-Graduation of Genomic Sciences and Biotechnology, Catholic University of Brasilia, Brasília, 70790-160, DF, Brazil
| | - Maria Cristina M. da Silva
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
| | - Raquel S. Oliveira
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Post-Graduation of Genomic Sciences and Biotechnology, Catholic University of Brasilia, Brasília, 70790-160, DF, Brazil
| | - Maria F. Grossi-de-Sa
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Post-Graduation of Genomic Sciences and Biotechnology, Catholic University of Brasilia, Brasília, 70790-160, DF, Brazil
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Rukarwa RJ, Mukasa SB, Odongo B, Ssemakula G, Ghislain M. Identification of relevant non-target organisms exposed to weevil-resistant Bt sweetpotato in Uganda. 3 Biotech 2014; 4:217-226. [PMID: 28324435 PMCID: PMC4026458 DOI: 10.1007/s13205-013-0153-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 07/01/2013] [Indexed: 11/26/2022] Open
Abstract
Assessment of the impact of transgenic crops on non-target organisms (NTO) is a prerequisite to their release into the target environment for commercial use. Transgenic sweetpotato varieties expressing Cry proteins (Bt sweetpotato) are under development to provide effective protection against sweetpotato weevils (Coleoptera) which cause severe economic losses in sub-Saharan Africa. Like any other pest control technologies, genetically engineered crops expressing insecticidal proteins need to be evaluated to assess potential negative effects on non-target organisms that provide important services to the ecosystem. Beneficial arthropods in sweetpotato production systems can include pollinators, decomposers, and predators and parasitoids of the target insect pest(s). Non-target arthropod species commonly found in sweetpotato fields that are related taxonomically to the target pests were identified through expert consultation and literature review in Uganda where Bt sweetpotato is expected to be initially evaluated. Results indicate the presence of few relevant non-target Coleopterans that could be affected by Coleopteran Bt sweetpotato varieties: ground, rove and ladybird beetles. These insects are important predators in sweetpotato fields. Additionally, honeybee (hymenoptera) is the main pollinator of sweetpotato and used for honey production. Numerous studies have shown that honeybees are unaffected by the Cry proteins currently deployed which are homologous to those of the weevil-resistant Bt sweetpotato. However, because of their feeding behaviour, Bt sweetpotato represents an extremely low hazard due to negligible exposure. Hence, we conclude that there is good evidence from literature and expert opinion that relevant NTOs in sweetpotato fields are unlikely to be affected by the introduction of Bt sweetpotato in Uganda.
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Affiliation(s)
- R J Rukarwa
- School of Agricultural Sciences, Makerere University, P.O. Box 7062, Kampala, Uganda.
| | - S B Mukasa
- School of Agricultural Sciences, Makerere University, P.O. Box 7062, Kampala, Uganda
| | - B Odongo
- African Institute for Capacity Development, P.O. Box 46179, Nairobi GPO, 00100, Kenya
| | - G Ssemakula
- National Crop Resources Research Institute (NaCRRI), P.O. Box 7084, Namulonge, Kampala, Uganda
| | - M Ghislain
- International Potato Center, P.O. Box 25171, Nairobi, 00603, Kenya
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Feng M, Zhao J, Zhang J, Hu Z, Wu W. Fluorescence localization and comparative ultrastructural study of periplocoside NW from Periploca sepium Bunge in the midgut of the oriental amyworm, Mythimna separata Walker (Lepidoptera: Noctuidae). Toxins (Basel) 2014; 6:1575-85. [PMID: 24831268 PMCID: PMC4052253 DOI: 10.3390/toxins6051575] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 04/25/2014] [Accepted: 05/05/2014] [Indexed: 11/16/2022] Open
Abstract
Periplocoside NW (PSNW) is a novel insecticidal compound isolated from the root bark of Periploca sepium Bunge and has potent stomach toxicity against some insect pests. Previous studies showed that the Mythimna separata larva is sensitive to PSNW, but the Agrotis ispilon larva is insensitive. In this study, preliminary target localization on the midgut of M. separata larvae was conducted via a fluorescence labeling technique. A comparative ultrastructural study on the effects of PSNW on the midguts of M. separata and A. ispilon larvae was performed. Symptom observation results showed that typical stomach toxicity was induced by PSNW in M. separata larvae. Fluorescence localization results showed that PSNW binds to the midgut cells of M. separata larvae. Ultrastructure observations showed destruction of the microvilli, organelle, and cytomembrane in the midgut cells of M. separata larvae, whereas no obvious changes were observed in midgut cells of A. ispilon larvae. These results were consistent with the insecticidal activity of PSNW. Therefore, PSNW might act on the midgut tissues of the insects, and one or more binding sites of PSNW may exist in M. separata larvae midgut cell cytomembranes.
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Affiliation(s)
- Mingxing Feng
- Institute of Pesticide Science, Northwest Agriculture and Forestry University, Yangling 712100, China.
| | - Juan Zhao
- Institute of Pesticide Science, Northwest Agriculture and Forestry University, Yangling 712100, China.
| | - Jiwen Zhang
- Institute of Pesticide Science, Northwest Agriculture and Forestry University, Yangling 712100, China.
| | - Zhaonong Hu
- Institute of Pesticide Science, Northwest Agriculture and Forestry University, Yangling 712100, China.
| | - Wenjun Wu
- Institute of Pesticide Science, Northwest Agriculture and Forestry University, Yangling 712100, China.
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Lytvyn DI, Syvura VV, Kurylo VV, Olenieva VD, Yemets AI, Blume YB. Creation of transgenic sugar beet lines expressing insect pest resistance genes cry1C and cry2A. CYTOL GENET+ 2014. [DOI: 10.3103/s0095452714020078] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Bacillus thuringiensis subsp. israelensis and its dipteran-specific toxins. Toxins (Basel) 2014; 6:1222-43. [PMID: 24686769 PMCID: PMC4014730 DOI: 10.3390/toxins6041222] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 03/10/2014] [Accepted: 03/14/2014] [Indexed: 01/05/2023] Open
Abstract
Bacillus thuringiensis subsp. israelensis (Bti) is the first Bacillus thuringiensis to be found and used as an effective biological control agent against larvae of many mosquito and black fly species around the world. Its larvicidal activity resides in four major (of 134, 128, 72 and 27 kDa) and at least two minor (of 78 and 29 kDa) polypeptides encoded respectively by cry4Aa, cry4Ba, cry11Aa, cyt1Aa, cry10Aa and cyt2Ba, all mapped on the 128 kb plasmid known as pBtoxis. These six δ-endotoxins form a complex parasporal crystalline body with remarkably high, specific and different toxicities to Aedes, Culex and Anopheles larvae. Cry toxins are composed of three domains (perforating domain I and receptor binding II and III) and create cation-selective channels, whereas Cyts are composed of one domain that acts as well as a detergent-like membrane perforator. Despite the low toxicities of Cyt1Aa and Cyt2Ba alone against exposed larvae, they are highly synergistic with the Cry toxins and hence their combinations prevent emergence of resistance in the targets. The lack of significant levels of resistance in field mosquito populations treated for decades with Bti-bioinsecticide suggests that this bacterium will be an effective biocontrol agent for years to come.
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Mode of Action and Specificity of Bacillus thuringiensis Toxins in the Control of Caterpillars and Stink Bugs in Soybean Culture. ISRN MICROBIOLOGY 2014; 2014:135675. [PMID: 24575310 PMCID: PMC3918364 DOI: 10.1155/2014/135675] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 11/26/2013] [Indexed: 01/12/2023]
Abstract
The bacterium Bacillus thuringiensis (Bt) produces delta-endotoxins that possess toxic properties and can be used as biopesticides, as well as a source of genes for the construction of transgenic plants resistant to insects. In Brazil, the introduction of Bt soybean with insecticidal properties to the velvetbean caterpillar, the main insect pest of soybean, has been seen a promising tool in the management of these agroecosystems. However, the increase in stink bug populations in this culture, in various regions of the country, which are not susceptible to the existing genetically modified plants, requires application of chemicals that damage the environment. Little is known about the actual toxicity of Bt to Hemiptera, since these insects present sucking mouthparts, which hamper toxicity assays with artificial diets containing toxins of this bacterium. In recent studies of cytotoxicity with the gut of different hemipterans, susceptibility in the mechanism of action of delta-endotoxins has been demonstrated, which can generate promising subsidies for the control of these insect pests in soybean. This paper aims to review the studies related to the selection, application and mode of action of Bt in the biological control of the major pest of soybean, Anticarsia gemmatalis, and an analysis of advances in research on the use of Bt for control hemipterans.
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Castagnola A, Stock SP. Common Virulence Factors and Tissue Targets of Entomopathogenic Bacteria for Biological Control of Lepidopteran Pests. INSECTS 2014; 5:139-66. [PMID: 24634779 PMCID: PMC3952272 DOI: 10.3390/insects5010139] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Revised: 12/13/2013] [Accepted: 12/17/2013] [Indexed: 01/13/2023]
Abstract
This review focuses on common insecticidal virulence factors from entomopathogenic bacteria with special emphasis on two insect pathogenic bacteria Photorhabdus (Proteobacteria: Enterobacteriaceae) and Bacillus (Firmicutes: Bacillaceae). Insect pathogenic bacteria of diverse taxonomic groups and phylogenetic origin have been shown to have striking similarities in the virulence factors they produce. It has been suggested that the detection of phage elements surrounding toxin genes, horizontal and lateral gene transfer events, and plasmid shuffling occurrences may be some of the reasons that virulence factor genes have so many analogs throughout the bacterial kingdom. Comparison of virulence factors of Photorhabdus, and Bacillus, two bacteria with dissimilar life styles opens the possibility of re-examining newly discovered toxins for novel tissue targets. For example, nematodes residing in the hemolymph may release bacteria with virulence factors targeting neurons or neuromuscular junctions. The first section of this review focuses on toxins and their context in agriculture. The second describes the mode of action of toxins from common entomopathogens and the third draws comparisons between Gram positive and Gram negative bacteria. The fourth section reviews the implications of the nervous system in biocontrol.
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Affiliation(s)
- Anaïs Castagnola
- Center for Insect Science, University of Arizona, 1007 E. Lowell Street, Tucson, AZ 85721, USA; E-Mail:
| | - S. Patricia Stock
- Department of Entomology, University of Arizona, 1140 E. South Campus Dr., Tucson, AZ 85721, USA
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Muñoz F, Palomares-Jerez MF, Daleo G, Villalaín J, Guevara MG. Possible mechanism of structural transformations induced by StAsp-PSI in lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:339-47. [DOI: 10.1016/j.bbamem.2013.08.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 08/02/2013] [Accepted: 08/06/2013] [Indexed: 01/19/2023]
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Qin H, Driks A. Contrasting evolutionary patterns of spore coat proteins in two Bacillus species groups are linked to a difference in cellular structure. BMC Evol Biol 2013; 13:261. [PMID: 24283940 PMCID: PMC4219348 DOI: 10.1186/1471-2148-13-261] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 11/20/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Bacillus subtilis-group and the Bacillus cereus-group are two well-studied groups of species in the genus Bacillus. Bacteria in this genus can produce a highly resistant cell type, the spore, which is encased in a complex protective protein shell called the coat. Spores in the B. cereus-group contain an additional outer layer, the exosporium, which encircles the coat. The coat in B. subtilis spores possesses inner and outer layers. The aim of this study is to investigate whether differences in the spore structures influenced the divergence of the coat protein genes during the evolution of these two Bacillus species groups. RESULTS We designed and implemented a computational framework to compare the evolutionary histories of coat proteins. We curated a list of B. subtilis coat proteins and identified their orthologs in 11 Bacillus species based on phylogenetic congruence. Phylogenetic profiles of these coat proteins show that they can be divided into conserved and labile ones. Coat proteins comprising the B. subtilis inner coat are significantly more conserved than those comprising the outer coat. We then performed genome-wide comparisons of the nonsynonymous/synonymous substitution rate ratio, dN/dS, and found contrasting patterns: Coat proteins have significantly higher dN/dS in the B. subtilis-group genomes, but not in the B. cereus-group genomes. We further corroborated this contrast by examining changes of dN/dS within gene trees, and found that some coat protein gene trees have significantly different dN/dS between the B subtilis-clade and the B. cereus-clade. CONCLUSIONS Coat proteins in the B. subtilis- and B. cereus-group species are under contrasting selective pressures. We speculate that the absence of the exosporium in the B. subtilis spore coat effectively lifted a structural constraint that has led to relaxed negative selection pressure on the outer coat.
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Affiliation(s)
- Hong Qin
- Department of Biology, Spelman College, Atlanta, GA 30314, USA.
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Zhang Q, Hua G, Bayyareddy K, Adang MJ. Analyses of α-amylase and α-glucosidase in the malaria vector mosquito, Anopheles gambiae, as receptors of Cry11Ba toxin of Bacillus thuringiensis subsp. jegathesan. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:907-915. [PMID: 23872242 DOI: 10.1016/j.ibmb.2013.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 06/28/2013] [Accepted: 07/08/2013] [Indexed: 06/02/2023]
Abstract
Bacillus thuringiensis subsp. jegathesan produces Cry11Ba crystal protein with high toxicity to mosquito larvae. The Cry11Ba toxicity is dependent on its receptors on mosquito larval midgut epithelial cells. Previously, a cadherin-like protein (AgCad2), aminopeptidase (AgAPN2) and alkaline phosphatase (AgALP1) were reported to be involved in regulation of Cry11Ba toxicity on Anopheles gambiae larvae. Here, the cDNAs encoding α-amylase (AgAmy1) and α-glucosidase (Agm3) were cloned from A. gambiae larva midgut. Both are glycophosphatidylinositol (GPI) anchored proteins on brush border membranes (BBMV). Immunohistochemistry revealed their localization on different regions of the larval midgut. AgAmy1 and Agm3 bound Cry11Ba with high affinity, 37.6 nM and 21.1 nM respectively. Cry11Ba toxicity against A. gambiae larvae was neutralized by both AgAmy1 and Agm3. The results provide evidence that both AgAmy1 and Agm3 function as receptors of Cry11Ba in A. gambiae.
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Affiliation(s)
- Qi Zhang
- Department of Entomology, University of Georgia, Athens, GA 30602-2603, USA
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Hjältén J, Axelsson EP, Julkunen-Tiitto R, Wennström A, Pilate G. Innate and introduced resistance traits in genetically modified aspen trees and their effect on leaf beetle feeding. PLoS One 2013; 8:e73819. [PMID: 24040084 PMCID: PMC3769380 DOI: 10.1371/journal.pone.0073819] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 07/24/2013] [Indexed: 11/25/2022] Open
Abstract
Genetic modifications of trees may provide many benefits, e.g. increase production, and mitigate climate change and herbivore impacts on forests. However, genetic modifications sometimes result in unintended effects on innate traits involved in plant-herbivore interactions. The importance of intentional changes in plant defence relative to unintentional changes and the natural variation among clones used in forestry has not been evaluated. By a combination of biochemical measurements and bioassays we investigated if insect feeding on GM aspens is more affected by intentional (induction Bt toxins) than of unintentional, non-target changes or clonal differences in innate plant defence. We used two hybrid wildtype clones (Populus tremula x P. tremuloides and Populus tremula x P. alba) of aspen that have been genetically modified for 1) insect resistance (two Bt lines) or 2) reduced lignin properties (two lines COMT and CAD), respectively. Our measurements of biochemical properties suggest that unintended changes by GM modifications (occurring due to events in the transformation process) in innate plant defence (phenolic compounds) were generally smaller but fundamentally different than differences seen among different wildtype clones (e.g. quantitative and qualitative, respectively). However, neither clonal differences between the two wildtype clones nor unintended changes in phytochemistry influenced consumption by the leaf beetle (Phratora vitellinae). By contrast, Bt induction had a strong direct intended effect as well as a post experiment effect on leaf beetle consumption. The latter suggested lasting reduction of beetle fitness following Bt exposure that is likely due to intestinal damage suffered by the initial Bt exposure. We conclude that Bt induction clearly have intended effects on a target species. Furthermore, the effect of unintended changes in innate plant defence traits, when they occur, are context dependent and have in comparison to Bt induction probably less pronounced effect on targeted herbivores.
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Affiliation(s)
- Joakim Hjältén
- Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Science, Umeå, Sweden
- * E-mail:
| | - E. Petter Axelsson
- Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Science, Umeå, Sweden
| | | | - Anders Wennström
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
| | - Gilles Pilate
- INRA, UR0588 Amélioration, Génétique et Physiologie Forestières, Orléans, France
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Benfarhat-Touzri D, Ben Amira A, Ben khedher S, Givaudan A, Jaoua S, Tounsi S. Combinatorial effect of Bacillus thuringiensis kurstaki and Photorhabdus luminescens against Spodoptera littoralis (Lepidoptera: Noctuidae). J Basic Microbiol 2013; 54:1160-5. [PMID: 23908000 DOI: 10.1002/jobm.201300142] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 06/01/2013] [Indexed: 01/17/2023]
Abstract
Spodoptera littoralis, one of the major pests of many important crop plants, is more susceptible to Bacillus thuringiensis aizawai delta-endotoxins than to those of Bacillus thuringiensis kurstaki. Within the framework of the development of efficient bioinsecticides and the prevention against insect resistance, we tested the effect of mixing B. thuringiensis kurstaki delta-endotoxins and Photorhabdus luminescens cells on S. littoralis growth. The obtained results showed that the growth inhibition of this insect was more effective when B. thuringiensis kurstaki spore-crystal mixture and Photorhabdus luminescens cells were used in combination. Furthermore, this synergism is mainly due to the presence of Cry1Ac, which is one of the three delta-endotoxins that form the crystal of B. thuringiensis kurstaki strain BNS3 in addition to Cry1Aa and Cry2Aa. This work shows a possibility to use B. thuringiensis as a delivery means for Photorhabdus bacteria in order to infect the insect hemocoel and to reduce the risk of developing resistance in the target organism.
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Affiliation(s)
- Dalel Benfarhat-Touzri
- Biopesticides Team (LPIP), Centre of Biotechnology of Sfax, University of Sfax, P.O. Box "1177", 3018, Sfax, Tunisia
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Kos M, Houshyani B, Overeem AJ, Bouwmeester HJ, Weldegergis BT, van Loon JJA, Dicke M, Vet LEM. Genetic engineering of plant volatile terpenoids: effects on a herbivore, a predator and a parasitoid. PEST MANAGEMENT SCIENCE 2013; 69:302-311. [PMID: 22933413 DOI: 10.1002/ps.3391] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 07/05/2012] [Accepted: 07/17/2012] [Indexed: 06/01/2023]
Abstract
BACKGROUND Most insect-resistant transgenic crops employ toxins to control pests. A novel approach is to enhance the effectiveness of natural enemies by genetic engineering of the biosynthesis of volatile organic compounds (VOCs). Before the commercialisation of such transgenic plants can be pursued, detailed fundamental studies of their effects on herbivores and their natural enemies are necessary. The linalool/nerolidol synthase gene FaNES1 was constitutively expressed from strawberry in three Arabidopsis thaliana accessions, and the behaviour of the aphid Brevicoryne brassicae L., the parasitoid Diaeretiella rapae McIntosh and the predator Episyrphus balteatus de Geer was studied. RESULTS Transgenic FaNES1-expressing plants emitted (E)-nerolidol and larger amounts of (E)-DMNT and linalool. Brevicoryne brassicae was repelled by the transgenic lines of two of the accessions, whereas its performance was not affected. Diaeretiella rapae preferred aphid-infested transgenic plants over aphid-infested wild-type plants for two of the accessions. In contrast, female E. balteatus predators did not differentiate between aphid-infested transgenic or wild-type plants. CONCLUSION The results indicate that the genetic engineering of plants to modify their emission of VOCs holds considerable promise for facilitating biological control of herbivores. Validation for crop plants is a necessary next step to assess the usefulness of modified volatile emission in integrated pest management.
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Affiliation(s)
- Martine Kos
- Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands.
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