Interaction of the Bacillus sphaericus mosquito larvicidal proteins

1990 ◽  
Vol 36 (12) ◽  
pp. 870-878 ◽  
Author(s):  
Elizabeth W. Davidson ◽  
Coreen Oei ◽  
Marian Meyer ◽  
Allan L. Bieber ◽  
John Hindley ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Sequence Analysis ◽  
Key Words ◽  
Culex Quinquefasciatus ◽  
Bacillus Sphaericus ◽  
Insecticidal Proteins ◽  
Posterior Midgut ◽  
Sds Page ◽  
Reduced Activity

Genes for 51.4- and 41.9-kDa insecticidal proteins of Bacillus sphaericus were separately cloned and expressed in Escherichia coli. Both proteins were required for toxicity. Approximately equal numbers of cells containing the 51.4- and 41.9-kDa proteins produced the greatest toxicity; excess 41.9-kDa protein did not affect toxicity, whereas excess 51.4-kDa protein reduced activity. Larvae were killed when 41.9-kDa protein was fed up to 24 h after the 51.4-kDa protein, but not when the order of feeding was reversed. Radiolabelled toxins bound in approximately equal amounts to the gastric caecum and posterior midgut of Culex quinquefasciatus larvae. Radiolabelled 51.4-kDa protein was rapidly degraded by ca. 12–13 kDa in the larval gut, while 41.9-kDa protein was degraded by 1–2 kDa. Nonreduced toxin extracted from B. sphaericus produced a band on SDS–PAGE of ca. 68–74 kDa that contained both 51.4- and 41.9-kDa proteins based on sequence analysis, and a band of ca. 51 kDa that contained primarily 41.9-kDa protein. Escherichia coli containing 51.4-kDa protein enhanced toxicity of the latter eluted SDS-PAGE band. These proteins may associate very strongly, and trace amounts of 51.4-kDa protein in preparations of 41.9-kDa protein from B. sphaericus may be responsible for the previously reported toxicity of the latter. Key words: Bacillus sphaericus, toxin, mosquito, cloning.

scholarly journals Mtx Toxins Synergize Bacillus sphaericus and Cry11Aa against Susceptible and Insecticide-Resistant Culex quinquefasciatus Larvae

2007 ◽  
Vol 73 (19) ◽  
pp. 6066-6071 ◽  
Author(s):  
Margaret C. Wirth ◽  
Yangkun Yang ◽  
William E. Walton ◽  
Brian A. Federici ◽  
Colin Berry
Keyword(s):  
Escherichia Coli ◽  
Bacillus Thuringiensis ◽  
Insecticide Resistance ◽  
Culex Quinquefasciatus ◽  
Vegetative Growth ◽  
Bacillus Sphaericus ◽  
Highly Active ◽  
Level Of Activity ◽  
Low Concentrations ◽  
High Level

ABSTRACT Two mosquitocidal toxins (Mtx) of Bacillus sphaericus, which are produced during vegetative growth, were investigated for their potential to increase toxicity and reduce the expression of insecticide resistance through their interactions with other mosquitocidal proteins. Mtx-1 and Mtx-2 were fused with glutathione S-transferase and produced in Escherichia coli, after which lyophilized powders of these fusions were assayed against Culex quinquefasciatus larvae. Both Mtx proteins showed a high level of activity against susceptible C. quinquefasciatus mosquitoes, with 50% lethal concentrations (LC50) of Mtx-1 and Mtx-2 of 0.246 and 4.13 μg/ml, respectively. The LC50s were 0.406 to 0.430 μg/ml when Mtx-1 or Mtx-2 was mixed with B. sphaericus, and synergy improved activity and reduced resistance levels. When the proteins were combined with a recombinant Bacillus thuringiensis strain that produces Cry11Aa, the mixtures were highly active against Cry11A-resistant larvae and resistance was also reduced. The mixture of two Mtx toxins and B. sphaericus was 10 times more active against susceptible mosquitoes than B. sphaericus alone, demonstrating the influence of relatively low concentrations of these toxins. These results show that, similar to Cyt toxins from B. thuringiensis subsp. israelensis, Mtx toxins can increase the toxicity of other mosquitocidal proteins and may be useful for both increasing the activity of commercial bacterial larvicides and managing potential resistance to these substances among mosquito populations.

A Study of the Abundance of Some Adult Culicine Mosquitoes in Ten Villages of Chitwan District, Nepal

2009 ◽  
Vol 24 ◽  
pp. 103-112
Author(s):  
Vaijayanti Devi Neupane ◽  
Ishan Gautam ◽  
A. S. Tamrakar ◽  
Shambhu Raj Shrestha
Keyword(s):  
Natural History ◽  
Key Words ◽  
Culex Quinquefasciatus ◽  
Natural History Museum ◽  
History Museum ◽  
Post Monsoon

A study was carried out at 10 villages of Chitwan District of Nepal during August-September, 1997 to March- April, 1998. A total of 12 species among 1197 samples were collected. Culex quinquefasciatus, Cx. fuscocephala, Cx. tritaeniorhynchus, Cx. gelidus, Cx. thelieri were previously reported, vector of different mosquito born diseases were recorded. Cx. quinquefasciatus was the most abundant both in post monsoon (26.90%) and pre monsoon (18.7%). Highest resting density (Human) of 9.33 was recorded in Post Monsoon at 25.75º C in Champanagar. Indoor resting density (Cattle) was highest in Suryapur at 22º C in Post Monsoon. The highest outdoor density (0.22) was at 22.5º C in Kholesimal in Pre Monsoon. Resting habit of Cx. tritaeniorhynchus & Cx. mimulus was infinitive in Post Monsoon.  Key Words:  Culex; JE Filariasis;  Abundant;  Resting habit; Chitwan. Journal of Natural History Museum Vol. 24, 2009,Page: 103-113 

scholarly journals Molecular surveillance of shiga toxigenic Escherichia coli in selected beef abattoirs in Osun State Nigeria

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Femi Ayoade ◽  
Judith Oguzie ◽  
Philomena Eromon ◽  
Omolola E. Omotosho ◽  
Tosin Ogunbiyi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Sequence Analysis ◽  
Block Design ◽  
Latex Agglutination ◽  
Pcr Analysis ◽  
Accession Number ◽  
E Coli ◽  
Representative Isolate ◽  
Randomized Block Design ◽  
Toxigenic Strains

AbstractShiga toxigenic strains of E. coli (STEC) known to be etiological agents for diarrhea were screened for their incidence/occurrence in selected abattoirs sources in Osogbo metropolis of Osun State, Nigeria using a randomized block design. Samples were plated directly on selective and differential media and E. coli isolates. Multiplex PCR analysis was used to screen for the presence of specific virulence factors. These were confirmed serologically as non-O157 STEC using latex agglutination serotyping kit. Sequence analysis of PCR products was performed on a representative isolate showing the highest combination of virulence genes using the 16S gene for identification purposes only. Results showed that the average cfu/cm2 was significantly lower in the samples collected at Sekona-2 slaughter slab compared with those collected at Al-maleek batch abattoir and Sekona-1 slaughter slab in ascending order at P = 0.03. Moreover, the average cfu/cm2E. coli in samples collected from butchering knife was significantly lower when compared with that of the workers’ hand (P = 0.047) and slaughtering floor (P = 0.047) but not with the slaughter table (P = 0.98) and effluent water from the abattoir house (P = 0.39). These data suggest that the abattoir type may not be as important in the prevalence and spread of STEC as the hygiene practices of the workers. Sequence analysis of a representative isolate showed 100% coverage and 96.46% percentage identity with Escherichia coli O113:H21 (GenBank Accession number: CP031892.1) strain from Canada. This sequence was subsequently submitted to GenBank with accession number MW463885. From evolutionary analyses, the strain from Nigeria, sequenced in this study, is evolutionarily distant when compared with the publicly available sequences from Nigeria. Although no case of E. coli O157 was found within the study area, percent occurrence of non-O157 STEC as high as 46.3% at some of the sampled sites is worrisome and requires regulatory interventions in ensuring hygienic practices at the abattoirs within the study area.

Comparison of colony and stool blots for detection of enteropathogens by DNA probes

1991 ◽  
Vol 37 (5) ◽  
pp. 407-410
Author(s):  
Mônica A. M. Vieira ◽  
Beatriz E. C. Guth ◽  
Tânia A. T. Gomes
Keyword(s):  
Escherichia Coli ◽  
Key Words ◽  
Sensitivity And Specificity ◽  
Dna Probes ◽  
Type I ◽  
Enteropathogenic Escherichia Coli ◽  
Key Words Dna ◽  
E Coli ◽  
Heat Stable

DNA probes that identify genes coding for heat-labile type I (LT-I) and heat-stable type 1 (ST-I) enterotoxins, enteropathogenic Escherichia coli adherence factor (EAF), and Shigella-like, invasiveness (INV) are used to evaluate the sensitivity and specificity of stool blots in comparison with the sensitivity and specificity of colony blots in detecting enteropathoghens. The sensitivities of the probes in stool blots are 91.7% for the LT-I probe, 76.9% for the ST-I probes, 78.9% for the EAF probe, and 45.5% for the INV probe. The specificity of all probes is higher than 95%. In general, the stool blot method identifies as many if not more LT-I-, ST-I-, and EAF-producing E. coli infections than the colony blots. Key words: DNA probes, stool blots, enteropathogens, diagnosis.

Developing structure-based models to predict substrate specificity of D-group (Type II) molybdenum enzymes: application to a molybdo-enzyme of unknown function from Archaeoglobus fulgidus

2006 ◽  
Vol 34 (1) ◽  
pp. 118-121 ◽  
Author(s):  
E.J. Dridge ◽  
D.J. Richardson ◽  
R.J. Lewis ◽  
C.S. Butler
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Sequence Analysis ◽  
Archaeoglobus Fulgidus ◽  
Substrate Selectivity ◽  
Type Ii ◽  
Amino Acid Residues ◽  
Sequence Alignments ◽  
X Ray ◽  
Group Type

The AF0174–AF0176 gene cluster in Archaeoglobus fulgidus encodes a putative oxyanion reductase of the D-type (Type II) family of molybdo-enzymes. Sequence analysis reveals that the catalytic subunit AF0176 shares low identity (31–32%) and similarity (41–42%) to both NarG and SerA, the catalytic components of the respiratory nitrate and selenate reductases respectively. Consequently, predicting the oxyanion substrate selectivity of AF0176 has proved difficult based solely on sequence alignments. In the present study, we have modelled both AF0176 and SerA on the recently determined X-ray structure of the NAR (nitrate reductase) from Escherichia coli and have identified a number of key amino acid residues, conserved in all known NAR sequences, including AF0176, that we speculate may enhance selectivity towards trigonal planar (NO3−) rather than tetrahedral (SeO42− and ClO4−) substrates.

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