Colloid-osmotic lysis is a general feature of the mechanism of action of Bacillus thuringiensis δ-endotoxins with different insect specificity

Knowles, Barbara H.; Ellar, David J.

doi:10.1016/0304-4165(87)90167-x

Cited by 436 publications

(270 citation statements)

References 39 publications

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“…The toxic action of Bt in vivo is known to be dependent on the binding of activated toxin to the external surface of midgut microvilli, where the toxins appear to bind to specific proteins (Hofmann et al, 1988) and then intercalate, forming transmembrane cation pores (Knowles & Ellar, 1987) that lead to cell death. However, it has been shown recently that the CrylA and CrylIIA toxins can insert into planar lipid bilayers that have no protein receptors (Slatin et al, 1990).…”

Section: Discussionmentioning

confidence: 99%

Synthesis and toxicity of full-length and truncated bacterial CryIVD mosquitocidal proteins expressed in lepidopteran cells using a baculovirus vector

Pang

Frutos²,

Federici³

1992

Journal of General Virology

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Full-length (72K) and truncated (61K) CrylVD mosquitocidal proteins of Bacillus thuringiensis (Bt) were expressed in Spodoptera frugiperda cells and larvae of Trichoplusia ni using a baculovirus vector to investigate the role of CrylVD peptides in toxicity as well as to evaluate further the baculovirus/lepidopteran system for expressing Bt proteins. The crylVD genes were inserted into the Autographa californica multinucleo- Infected cells and purified inclusions from the virus (AcCrylVD) expressing the full-length protein were highly toxic to mosquito larvae, but similar preparations from the virus (AcCrylVD-C) expressing the truncated protein with a 9-6K deletion at the N terminus were non-toxic. Proteolysis with trypsin of CrylVD proteins produced by Bt and the recombinant AcMNPVs yielded peptides corresponding in size, showing that synthesis of mosquitocidal Bt proteins in lepidopteran cells occurred. The lack of toxicity of the truncated CryIVD protein, which like the toxic fulllength protein yielded a 34K protein on proteolysis that has been implicated in toxicity, indicates that by itself this protein is non-toxic. These results demonstrate the utility of the baculovirus system for expression of mosquitocidal Bt proteins and for investigation of their mode of action.

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Section: Discussionmentioning

confidence: 99%

Synthesis and toxicity of full-length and truncated bacterial CryIVD mosquitocidal proteins expressed in lepidopteran cells using a baculovirus vector

Pang

Frutos²,

Federici³

1992

Journal of General Virology

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“…d-Endotoxins are capable of forming pores in cell membranes (Knowles and Ellar, 1984;von Tersch et al, 1995). The relationship between pore formation and programmed cell death is unknown, but it is interesting that cytotoxic T lymphocytes can also induce apoptosis by secreting perforins, proteins which form pores in target cell membranes (Berke, 1995).…”

Section: Discussionmentioning

confidence: 99%

“…Perforin alone induces lysis, but not apoptosis of target cells. Similarly, d toxins induce insect cells in culture to undergo a colloidal-osmotic shock (Knowles and Ellar, 1984) resulting in lysis. It has not been reported if these cells undergo programmed cell death.…”

Section: Discussionmentioning

confidence: 99%

“…It has been shown that they bind with high affinity to receptors on the brush border membranes of larval midgut cells, and that this binding initiates a number of physiological changes in these cells. Lepidopteran-specific d-endotoxins have been reported to induce the formation of pores in brush border membrane vesicles (Knowles and Ellar, 1984;von Tersch et al, 1994), and to alter the transport of ions and amino acids across cell membranes (Sacchi et al 1986;Villa et al, 1995). However, the relationships between the events occurring after toxin binding, the cellular mechanisms leading to changes in midgut cell membranes, and their contributions to the death of larvae following toxin ingestion, are still poorly understood.…”

Section: Introductionmentioning

confidence: 99%

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A Bacillus thuringiensis δ-endotoxin induces programmed cell death in mosquito larvae

Smouse

Nishiura

1997

Cell Death Differ

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We present evidence that a d-endotoxin isolated from Bacillus thuringiensis subsp.israelensis induces programmed cell death in polytene midgut cells of Culex pipiens larvae. After exposure to toxin, polytene nuclei in the anterior region of the larval midgut undergo many of the morphological and physiological changes which are characteristic of apoptosis, including the ability to stain with the vital dye, acridine orange, and fragmentation of nuclear DNA as demonstrated by agarose gel electrophoresis and in situ TUNEL labeling. The temporal sequence of toxin ingestion, acridine orange staining and larval death suggests a cause and effect relationship between programmed cell death and larval death. Amino sugars that interfere with toxicity also interfere with the time course of acridine orange staining of larval polytene nuclei. The toxin first causes programmed cell death of anterior midgut and gastric caeca cells and, subsequently, posterior midgut cells. This pattern is similar to the temporal sequence of larval polytene cell death that occurs during metamorphosis. From the size and distribution of the nuclei that are stained with acridine orange, it appears that only polytene midgut cells are affected by toxin and that the diploid regenerative cell are not affected.

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“…Upon ingestion, the crystal protein is solubilized and processed by proteolytic enzymes to an active toxin, which binds to specific receptors on the apical microvillus membrane of the epithelial midgut cell. Subsequent insertion of active toxin into the membrane leads to disruption of osmotic balance and eventual lysis of epithelial cells, causing extensive damage to the midgut and, ultimately, larval death (Knowles and Ellar 1987;Hofmann et al 1988;Knowles 1994;Schnepf et al 1998;de Maagd et al 2001;Whalon and Wingerd 2003).…”

Section: Introductionmentioning

confidence: 99%

RecombinantBacillus thuringiensisstrain shows high insecticidal activity againstPlutella xylostellaandLeptinotarsa decemlineatawithout affecting nontarget species in the field

Wang

Zhang

Song

et al. 2008

Journal of Applied Microbiology

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Aims: To construct a recombinant Bacillus thuringiensis (Bt) strain with broad insecticidal spectrum and investigate its impact on nontarget organisms in field. Method and Results: The cry‐type gene of wild Bt strain UV17 was identified and a novel cry1Ba gene was cloned. The cry3Aa7 gene, which was highly toxic to coleopteran pests, was introduced into UV17, and a recombinant strain designated as UV173A was obtained. Bioassay results showed that UV173A was not only highly toxic against Plutella xylostella (50% lethal concentration [LC50] = 18·03 μg ml–1), but also against coleopteran Leptinotarsa decernlineata (LC50 = 0·19 mg ml–1). The recombinant strain was then tested in field trials to monitor its spatial variation of population and to investigate the impact on nontarget invertebrates. Conclusions: A recombinant Bt stain UV173A with broad insecticidal spectrum was obtained, and it did not cause adverse effects on the population of nontarget organisms. Significance and Impact of the Study: The results obtained here indicated that cry1Ba3 gene may be useful for the resistance management of P. xylostella, and the recombinant stain UV173A was potential for field application against some crucifer vegetable pests as well as L. decemlineata.

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Colloid-osmotic lysis is a general feature of the mechanism of action of Bacillus thuringiensis δ-endotoxins with different insect specificity

Cited by 436 publications

References 39 publications

Synthesis and toxicity of full-length and truncated bacterial CryIVD mosquitocidal proteins expressed in lepidopteran cells using a baculovirus vector

Synthesis and toxicity of full-length and truncated bacterial CryIVD mosquitocidal proteins expressed in lepidopteran cells using a baculovirus vector

A Bacillus thuringiensis δ-endotoxin induces programmed cell death in mosquito larvae

RecombinantBacillus thuringiensisstrain shows high insecticidal activity againstPlutella xylostellaandLeptinotarsa decemlineatawithout affecting nontarget species in the field

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