Effect of sublethal Bacillus thuringiensis crystal endotoxin treatment on the larval midgut of a moth, Manduca: SEM study

Spies, Andre; Spence, Kemet D.

doi:10.1016/0040-8166(85)90056-4

Cited by 75 publications

(42 citation statements)

References 18 publications

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“…Rapid division of stem cells is normally restricted to the period of the larval moult, but is also responsible for cell replacement during repair (17,21). All of the larvae examined in this study were at the midmoult stage; hence, the stem cell proliferation observed was a reflection of the damage caused by the cyclotides.…”

Section: Discussionmentioning

confidence: 86%

“…Swelling and lysis of the columnar and goblet cells was evident at both light and electron microscopic levels, providing an explanation for the insecticidal activity of cyclotides against lepidopteran pests. The changes in morphology observed resemble the substantial changes to the insect midgut that are induced by the delta-endotoxins from Bacillus thuringiensis (17).…”

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confidence: 70%

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Plant cyclotides disrupt epithelial cells in the midgut of lepidopteran larvae

Barbeta¹,

Marshall

Gillon³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

204

202

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Several members of the Rubiaceae and Violaceae plant families produce a series of cyclotides or macrocyclic peptides of 28 -37 aa with an embedded cystine knot. The cyclic peptide backbone together with the knotted and strongly braced structure confers exceptional chemical and biological stability that has attracted attention for potential pharmaceutical applications. Cyclotides display a diverse range of biological activities, such as uterotonic action, anti-HIV activity, and neurotensin antagonism. In plants, their primary role is probably protection from insect attack. Ingestion of the cyclotide kalata B1 severely retards the growth of larvae from the Lepidopteran species Helicoverpa armigera. We examined the gut of these larvae after consumption of kalata B1 by light, scanning, and transmission electron microscopy. We established that kalata B1 induces disruption of the microvilli, blebbing, swelling, and ultimately rupture of the cells of the gut epithelium. The histology of this response is similar to the response of H. armigera larvae to the Bacillus thuringiensis delta-endotoxin, which is widely used to control these insect pests of crops such as cotton. circular peptides ͉ insecticidal ͉ kalata B1 ͉ Lepidoptera ͉ microscopy C yclotides are a series of cyclic minipeptides of 28-37 aa that are expressed at high levels in the leaves, stems, and roots of several plant species (1, 2). They have an unusual topology based on a cyclic peptide backbone together with a cystine knot in which two disulfide bonds are threaded by a third disulfide bond (2, 3). This structure forces hydrophobic amino acids onto the surface of the molecule, creating a hydrophobic face on the otherwise hydrophilic surface. The cyclotides are thus soluble in both organic and aqueous solvents and are very stable at extremes of pH and temperature (4). The absence of free N and C termini, together with the tightly packed cystine knot, also renders the cyclotides resistant to the activity of proteases (4). The cyclotides are the largest family of circular proteins, although others have been described in bacteria, plants, and animals (5).Cyclotides were first isolated from the African plant Oldenlandia affinis. Two peptides, kalata B1 and B2, were recognized as the active components in a traditional medicine used to accelerate childbirth (6). Additional members of the cyclotide family were subsequently identified in screening studies directed toward discovery of bioactive molecules such as neurotensin antagonists (7), inhibitors of HIV replication (8), and hemolytic agents (9). More than 100 cyclotides have since been isolated from various members of the Rubiaceae, Violaceae, and Cucurbitaceae plant families (10, 11). A single plant may have at least 12 cyclotide genes and produce dozens of different cyclotides (12)(13)(14). Although an earlier study reported antimicrobial activity (15), it appears that their predominant activity in plants is insecticidal (13, 16). Jennings et al. (13) demonstrated that Helicoverpa punctigera failed to devel...

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Section: Discussionmentioning

confidence: 86%

mentioning

confidence: 70%

Plant cyclotides disrupt epithelial cells in the midgut of lepidopteran larvae

Barbeta¹,

Marshall

Gillon³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

204

202

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“…The low-affinity interaction with ALP in the midgut lumen could account for a sufficient hindrance in the binding of Cry1Ac to its receptors on the microvillar membrane, preventing Cry1Ac crossing through the peritrophic membrane. A reduced amount of binding could be critical for resistance because it may allow gut-healing mechanisms to recover from the weak damage produced by the toxin that was able to bind (28,44). Additionally, because ALP does bind specifically to Cry1Ac toxin and not protoxin, and AR1 is resistant to toxin with little cross-resistance to protoxin, ALP might also play a role in changing the three-dimensional profile of the Cry1Ac toxin, exposing additional protease cleavage sites not found in susceptible insects.…”

Section: Fig 4 Effect Of Cry1ac Toxin On Kmentioning

confidence: 99%

Association of Cry1Ac Toxin Resistance in Helicoverpa zea (Boddie) with Increased Alkaline Phosphatase Levels in the Midgut Lumen

Caccia

Moar

Chandrashekhar

et al. 2012

Appl Environ Microbiol

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Resistance to Bacillus thuringiensis Cry1Ac toxin was characterized in a population of Helicoverpa zea larvae previously shown not to have an alteration in toxin binding as the primary resistance mechanism to this toxin. Cry1Ac-selected larvae (AR1) were resistant to protoxins and toxins of Cry1Ab, Cry1Ac, and the corresponding modified proteins lacking helix ␣-1 (Cry1AbMod and Cry1AcMod). When comparing brush border membrane vesicles (BBMVs) prepared from susceptible (LC) and AR1 larval midguts, there were only negligible differences in overall Cry1Ac toxin binding, though AR1 had 18% reversible binding, in contrast to LC, in which all binding was irreversible. However, no differences were detected in Cry1Ac-induced pore formation activity in BBMVs from both strains. Enzymatic activities of two putative Cry1Ac receptors (aminopeptidase N [APN] and alkaline phosphatase [ALP]) were significantly reduced (2-fold and 3-fold, respectively) in BBMVs from AR1 compared to LC larvae. These reductions corresponded to reduced protein levels in midgut luminal contents only in the case of ALP, with an almost 10-fold increase in specific ALP activity in midgut fluids from AR1 compared to LC larvae. Partially purified H. zea ALP bound Cry1Ac toxin in ligand blots and competed with Cry1Ac toxin for BBMV binding. Based on these results, we suggest the existence of at least one mechanism of resistance to Cry1A toxins in H. zea involving binding of Cry1Ac toxin to an ALP receptor in the larval midgut lumen of resistant larvae.

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“…Subsequently, the pore is formed (Masson et al, 1999) and the ion flux through that pore leads to cell lysis and the consequent death of the susceptible pest organisms Monnerat and Bravo, 2000). When the toxin dosage fails to kill the insect, its cells are substituted allowing normal feeding to proceed and the recuperation of development of the insect (Spies and Spence, 1995). The midgut of the Lepidoptera is composed of pseudostratified epithelium, formed by three kinds of cells -columnar, globular (Cioffi, 1979) and regenerative -located on the base, between the columnar and the globular cells.…”

Section: Introductionmentioning

confidence: 99%

Histopathology and the lethal effect of Cry proteins and strains of Bacillus thuringiensis Berliner in Spodoptera frugiperda J.E. Smith Caterpillars (Lepidoptera, Noctuidae)

Knaak

Franz²,

Santos

et al. 2010

Braz. J. Biol.

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Among the phytophagous insects which attack crops, the fall armyworm, Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera, Noctuidae) is particularly harmful in the initial growth phase of rice plants. As a potential means of controlling this pest, and considering that the entomopathogen Bacillus thuringiensis Berliner demonstrates toxicity due to synthesis of the Cry protein, the present study was undertaken to evaluate this toxic effect of B. thuringiensis thuringiensis 407 (pH 408) and B. thuringiensis kurstaki HD-73 on S. frugiperda. The following method was used. Both bacterial strains were evaluated in vitro in 1 st instar S. frugiperda caterpillars, by means of histopathological assays. The Cry1Ab and Cry1Ac proteins, codified by the respective strains of B. thuringiensis, were evaluated in vivo by bioassays of 1 st instar S. frugiperda caterpillars in order to determine the Mean Lethal Concentration (LC 50 ). The results of the histopathological analysis of the midget of S. frugiperda caterpillars demonstrate that treatment with the B. thuringiensis thuringiensis strain was more efficient, because the degradations of the microvilosities started 9 hours after treatment application (HAT), while in the B. thuringiensis kurstaki the same effect was noticed only after 12 HAT. Toxicity data of the Cry1Ab and Cry1Ac proteins presented for the target-species LC 50 levels of 9.29 and 1.79 µg.cm , respectivamente. As cepas e proteínas sintetizadas por B. thuringiensis thuringiensis e B. thuringiensis kurstaki são eficientes no controle de S. frugiperda, e poderão ser usadas na produção de novos biopesticidas ou a utilização dos genes na transformação genética de Oryza sativa L. Histopatologia e efeito letal de cepas e proteínas Cry de Bacillus thuringiensis

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Effect of sublethal Bacillus thuringiensis crystal endotoxin treatment on the larval midgut of a moth, Manduca: SEM study

Cited by 75 publications

References 18 publications

Plant cyclotides disrupt epithelial cells in the midgut of lepidopteran larvae

Plant cyclotides disrupt epithelial cells in the midgut of lepidopteran larvae

Association of Cry1Ac Toxin Resistance in Helicoverpa zea (Boddie) with Increased Alkaline Phosphatase Levels in the Midgut Lumen

Histopathology and the lethal effect of Cry proteins and strains of Bacillus thuringiensis Berliner in Spodoptera frugiperda J.E. Smith Caterpillars (Lepidoptera, Noctuidae)

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