scholarly journals Mode of Action of Bacillus thuringiensis δ-Endotoxin : Ultrastructural Changes of Midgut Epithelium of Pieris, Lymantria and Ephestia Larvae

1981 ◽  
Vol 16 (3) ◽  
pp. 231-241 ◽  
Author(s):  
Yasuhisa ENDO ◽  
Junko NISHITSUTSUJI-UWO
Keyword(s):  
Bacillus Thuringiensis ◽  
Mode Of Action ◽  
Midgut Epithelium ◽  
Ultrastructural Changes ◽  
Delta Endotoxin

The initial stages in the action of an insecticidal delta-endotoxin of Bacillus thuringiensis var. israelensis on the epithelial cells of the malpighian tubules of the insect, Rhodnius prolixus

1988 ◽  
Vol 90 (1) ◽  
pp. 131-144
Author(s):  
S.H. Maddrell ◽  
N.J. Lane ◽  
J.B. Harrison ◽  
J.A. Overton ◽  
R.B. Moreton
Keyword(s):  
Bacillus Thuringiensis ◽  
Intercellular Junctions ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Ultrastructural Changes ◽  
Cytoplasmic Vacuolization ◽  
Large Numbers ◽  
Delta Endotoxin ◽  
High Concentrations ◽  
Very High

The effects of the 27 X 10(3) Mr insecticidal delta-endotoxin from Bacillus thuringiensis var. israelensis have been studied using, as a model system, isolated insect Malpighian tubules. At all concentrations of the toxin higher than 1 microgram ml-1 (4 X 10(−8) moll-1) applied to the outer surface of the tubules, fluid secretion failed within about 30 min. Except at very high concentrations, where failure always takes at least 30 s, there was an inverse relationship between the concentration of toxin and the time of failure of toxin-treated tubules. During exposure to toxin, the tubules were initially unaffected for a relatively long period and then rapid failure occurred. If the tubules were removed into toxin-free saline just before failure would have occurred, fluid secretion remained normal for at least 2 h, but on return to the origin toxin-containing saline failure was almost immediate. The toxin was found not to bind to the basement membrane. Ultrastructural changes became evident as tubule failure occurred. These initially involved modifications to the basal side of the cells, but later also to the luminal microvilli. Intercellular junctions became disassociated and cytoplasmic vacuolization occurred. The population of intramembranous particles in the basal membranes became reduced with time. Our findings suggest the following hypothesis for the initial stages in the interaction of the toxin with the tubules. Toxin molecules attach to the accessible cell membranes progressively and irreversibly. They do not readily associate by diffusing laterally in the membrane, so that toxic effects develop only when sufficiently large numbers of them attach close together. The molecules may then associate in some way as a complex, perhaps forming a pore in the membrane. Relatively few such pores lead rapidly to cell failure and death.

scholarly journals Larvicidal and adulticidal effects and ultrastructural changes of larvae midgut epithelium of Musca domestica (Diptera: Muscidae) fed with Bacillus thuringiensis var. kyushuensis

2019 ◽  
Vol 52 ◽  
Author(s):  
Lorrane de Andrade Pereira ◽  
Vitor dos Santos Baia Ferreira ◽  
Nahara de Souza Leite ◽  
Sandra Maria de Oliveira Souza ◽  
Margareth Maria de Carvalho Queiroz ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Musca Domestica ◽  
Midgut Epithelium ◽  
Ultrastructural Changes

Mode of action of CryIIA: a Bacillus thuringiensis delta-endotoxin

1994 ◽  
Vol 24 (10) ◽  
pp. 1025-1035 ◽  
Author(s):  
L ENGLISH ◽  
H ROBBINS ◽  
M VONTERSCH ◽  
C KULESZA ◽  
D AVE ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Mode Of Action ◽  
Delta Endotoxin

scholarly journals The Bacillus thuringiensis delta-endotoxin. Evidence for a two domain structure of the minimal toxic fragment.

1990 ◽  
Vol 265 (3) ◽  
pp. 1369-1375
Author(s):  
D Convents ◽  
C Houssier ◽  
I Lasters ◽  
M Lauwereys
Keyword(s):  
Bacillus Thuringiensis ◽  
Domain Structure ◽  
Delta Endotoxin

scholarly journals Analysis of the molecular basis of insecticidal specificity of Bacillus thuringiensis crystal δ-endotoxin

1987 ◽  
Vol 248 (1) ◽  
pp. 197-201 ◽  
Author(s):  
M Z Haider ◽  
D J Ellar
Keyword(s):  
Bacillus Thuringiensis ◽  
Membrane Proteins ◽  
Insect Cell ◽  
Receptor Interaction ◽  
Dual Specificity ◽  
Delta Endotoxin ◽  
Cell Membrane Proteins ◽  
Toxin Receptor ◽  
Osmotic Lysis ◽  
Initial Interaction

The mechanism of action and receptor binding of a dual-specificity Bacillus thuringiensis var. aizawai ICl delta-endotoxin was studied using insect cell culture. The native protoxin was labelled with 125I, proteolytically activated and the affinity of the resulting preparations for insect cell-membrane proteins was studied by blotting. The active preparations obtained by various treatments had characteristic specificity associated with unique polypeptides, and showed affinity for different membrane proteins. The lepidopteran-specific preparation (trypsin-treated protoxin containing 58 and 55 kDa polypeptides) bound to two membrane proteins in the lepidopteran cells but none in the dipteran cells. The dipteran-specific preparation (protoxin treated sequentially with trypsin and Aedes aegypti gut proteases, containing a 53 kDa polypeptide) bound to a 90 kDa membrane protein in the dipteran (A. aegypti) cells but bound to none in the lepidopteran cells or Drosophila melanogaster cells. The toxicity of trypsin-activated delta-endotoxin was completely inhibited by preincubation with D-glucose, suggesting a role for this carbohydrate in toxin-receptor interaction. The toxicity was also decreased by osmotic protectants to an extent proportional to their viscometric radius. These results support a proposal that initial interaction of toxin with a unique receptor determines the specificity of the toxin, following which cell death occurs by a mechanism of colloid osmotic lysis.

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