BINDING ASSAY OF BACILLUS THURINGIENSIS CRY1AC INSECTICIDAL CRYSTAL PROTEINS IN DIAMONDBACK MOTH

1998 ◽  
Vol 5 (4) ◽  
pp. 350-354
Author(s):  
Jianhong Li ◽  
Ray Akhurst ◽  
Ziniu Yu
2000 ◽  
Vol 28 (5) ◽  
pp. A438-A438
Author(s):  
Hiroshi Sakai ◽  
Tohru Komano ◽  
Masashi Yamagiwa

2002 ◽  
Vol 48 (3) ◽  
pp. 262-267 ◽  
Author(s):  
J Koskella ◽  
G Stotzky

The insecticidal toxins from Bacillus thuringiensis subspp. kurstaki (antilepidopteran), morrisoni strain tenebrionis (anticoleopteran), and israelensis (antidipteran) did not affect the growth of a variety of bacteria (8 gram-negative, 5 gram-positive, and a cyanobacterium), fungi (2 Zygomycetes, 1 Ascomycete, 2 Deuteromycetes, and 2 yeasts), and algae (primarily green and diatoms) in pure and mixed culture, as determined by dilution, disk-diffusion, and sporulation assays with purified free and clay-bound toxins. The insecticidal crystal proteins from B. thuringiensis subspp. kurstaki and israelensis had no antibiotic effect on various gram-positive bacteria.Key words: insecticidal toxins, Bacillus thuringiensis, microbiostatic, microbicidal.


1998 ◽  
Vol 64 (4) ◽  
pp. 1563-1565 ◽  
Author(s):  
B. Escriche ◽  
N. De Decker ◽  
J. Van Rie ◽  
S. Jansens ◽  
E. Van Kerkhove

ABSTRACT Bacillus thuringiensis insecticidal crystal proteins (ICPs) are thought to induce pore formation in midgut cell membranes of susceptible insects. Cry1Ca, which is significantly active inSpodoptera littoralis, made brush border membrane vesicles permeable to KCl (osmotic swelling was monitored by the light scattering technique); the marginally active ICPs Cry1Aa, Cry1Ab, and Cry1Ac did not.


1999 ◽  
Vol 65 (4) ◽  
pp. 1413-1419 ◽  
Author(s):  
Victoria Ballester ◽  
Francisco Granero ◽  
Bruce E. Tabashnik ◽  
Thomas Malvar ◽  
Juan Ferré

ABSTRACT Insecticidal crystal proteins from Bacillus thuringiensis in sprays and transgenic crops are extremely useful for environmentally sound pest management, but their long-term efficacy is threatened by evolution of resistance by target pests. The diamondback moth (Plutella xylostella) is the first insect to evolve resistance to B. thuringiensis in open-field populations. The only known mechanism of resistance to B. thuringiensis in the diamondback moth is reduced binding of toxin to midgut binding sites. In the present work we analyzed competitive binding of B. thuringiensis toxins Cry1Aa, Cry1Ab, Cry1Ac, and Cry1F to brush border membrane vesicles from larval midguts in a susceptible strain and in resistant strains from the Philippines, Hawaii, and Pennsylvania. Based on the results, we propose a model for binding of B. thuringiensis crystal proteins in susceptible larvae with two binding sites for Cry1Aa, one of which is shared with Cry1Ab, Cry1Ac, and Cry1F. Our results show that the common binding site is altered in each of the three resistant strains. In the strain from the Philippines, the alteration reduced binding of Cry1Ab but did not affect binding of the other crystal proteins. In the resistant strains from Hawaii and Pennsylvania, the alteration affected binding of Cry1Aa, Cry1Ab, Cry1Ac, and Cry1F. Previously reported evidence that a single mutation can confer resistance to Cry1Ab, Cry1Ac, and Cry1F corresponds to expectations based on the binding model. However, the following two other observations do not: the mutation in the Philippines strain affected binding of only Cry1Ab, and one mutation was sufficient for resistance to Cry1Aa. The imperfect correspondence between the model and observations suggests that reduced binding is not the only mechanism of resistance in the diamondback moth and that some, but not all, patterns of resistance and cross-resistance can be predicted correctly from the results of competitive binding analyses of susceptible strains.


2018 ◽  
Vol 5 ◽  
pp. 11-18
Author(s):  
Ganga G.C. ◽  
Charu Arjya ◽  
Yamuna Khadka ◽  
Sabina Dhamala

Objectives: The purpose of this study was to characterize the indigenous Bacillus thuringiensis (Bt) isolated from the soil samples of central development region of Terai. Methods: A total of 50 soil samples collected from cultivated and barren fields of Terai region. Isolation was carried out using the acetate selection protocol as described by (Russell and Al 1987) with a slight modification. The Nutrient broth (NB) was acetated by using 0.25M sodium acetate which is a selective enrichment method for isolation of Bt. Characterization of the isolate was done by phenotyping methods (microscopy and biochemical). Results: No distinct variation was observed between the isolates of cultivable and uncultivable lands. Bt were categorized into7 different types based on colony morphology. The dominant colony was fried egg type identical with the reference strain, followed by flat white type of colony. The result showed that even though the colony morphology is same but the ICPs (Insecticidal crystal proteins) shapes produced by them vary, rod shapes (53.57%), spherical (10.71%), ovoid (8.3%), amorphous (17.85%), capheaded (9.5%). ICPs morphology reveal the cry1, cry2, cry3, cry4, cry8, cry 9, cry10 and cry11 types of gene may be present in the native isolates. Conclusion: This study represents the first report of several indigenous Bacillus thuringiensis strains with significantly different ICPs producing stains from hot tropical climate.


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