scholarly journals Insecticidal Activity of Bacillus thuringiensis Cry1Bh1 against Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) and Other Lepidopteran Pests

2013 ◽  
Vol 79 (24) ◽  
pp. 7590-7597 ◽  
Author(s):  
Justin Lira ◽  
Jeff Beringer ◽  
Stephanie Burton ◽  
Samantha Griffin ◽  
Joel Sheets ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Insect Resistance ◽  
Ostrinia Nubilalis ◽  
Binding Sites ◽  
Membrane Binding ◽  
Cross Resistance ◽  
Content Type ◽  
Lepidopteran Pests ◽  
Resistant Strains ◽  
Membrane Binding Sites

ABSTRACTBacillus thuringiensisis an important source of insect resistance traits in commercial crops. In an effort to prolongB. thuringiensistrait durability, insect resistance management programs often include combinations of insecticidal proteins that are not cross resistant or have demonstrable differences in their site of action as a means to mitigate the development of resistant insect populations. In this report, we describe the activity spectrum of a novelB. thuringiensisCry protein, Cry1Bh1, against several lepidopteran pests, including laboratory-selectedB. thuringiensis-resistant strains ofOstrinia nubilalisandHeliothis virescensand progeny of field-evolvedB. thuringiensis-resistant strains ofPlutella xylostellaandSpodoptera frugiperda. Cry1Bh1 is active against susceptible andB. thuringiensis-resistant colonies ofO. nubilalis,P. xylostella, andH. virescensin laboratory diet-based assays, implying a lack of cross-resistance in these insects. However, Cry1Bh1 is not active against susceptible or Cry1F-resistantS. frugiperda. Further, Cry1Bh1 does not compete with Cry1Fa or Cry1Ab forO. nubilalismidgut brush border membrane binding sites. Cry1Bh1-expressing corn, while not completely resistant to insect damage, provided significantly better leaf protection against Cry1Fa-resistantO. nubilalisthan did Cry1Fa-expressing hybrid corn. The lack of cross-resistance with Cry1Ab and Cry1Fa along with independent membrane binding sites inO. nubilalismakes Cry1Bh1 a candidate to further optimize for in-plant resistance to this pest.

scholarly journals Toxicity and Binding Studies of Bacillus thuringiensis Cry1Ac, Cry1F, Cry1C, and Cry2A Proteins in the Soybean Pests Anticarsia gemmatalis and Chrysodeixis (Pseudoplusia) includens

2017 ◽  
Vol 83 (11) ◽  
Author(s):  
Yolanda Bel ◽  
Joel J. Sheets ◽  
Sek Yee Tan ◽  
Kenneth E. Narva ◽  
Baltasar Escriche
Keyword(s):  
Bacillus Thuringiensis ◽  
Binding Sites ◽  
Specific Binding ◽  
Management Strategies ◽  
Anticarsia Gemmatalis ◽  
Cross Resistance ◽  
Binding Studies ◽  
Content Type ◽  
Bt Toxins ◽  
Competition Binding

ABSTRACT Anticarsia gemmatalis (velvetbean caterpillar) and Chrysodeixis includens (soybean looper, formerly named Pseudoplusia includens) are two important defoliating insects of soybeans. Both lepidopteran pests are controlled mainly with synthetic insecticides. Alternative control strategies, such as biopesticides based on the Bacillus thuringiensis (Bt) toxins or transgenic plants expressing Bt toxins, can be used and are increasingly being adopted. Studies on the insect susceptibilities and modes of action of the different Bt toxins are crucial to determine management strategies to control the pests and to delay outbreaks of insect resistance. In the present study, the susceptibilities of both soybean pests to the Bt toxins Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa have been investigated. Bioassays performed in first-instar larvae showed that both insects are susceptible to all these toxins. Competition-binding studies carried out with Cry1Ac and Cry1Fa 125-iodine labeled proteins demonstrated the presence of specific binding sites for both of them on the midgut brush border membrane vesicles (BBMVs) of both A. gemmatalis and C. includens. Competition-binding experiments and specific-binding inhibition studies performed with selected sugars and lectins indicated that Cry1Ac and Cry1Fa share some, but not all, binding sites in the midguts of both insects. Also, the Cry1Ac- or Cry1Fa-binding sites were not shared with Cry1Ca or Cry2Aa in either soybean pest. This study contributes to the knowledge of Bt toxicity and midgut toxin binding sites in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa Bt proteins as candidate proteins for Bt-pyramided crops. IMPORTANCE In the present study, the toxicity and the mode of action of the Bacillus thuringiensis (Bt) toxins Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa in Anticarsia gemmatalis and Chrysodeixis includens (important defoliating pests of soybeans) have been investigated. These studies are crucial for determining management strategies for pest control. Bioassays showed that both insects were susceptible to the toxins. Competition-binding studies demonstrated the presence of Cry1Fa- and Cry1Ac-specific binding sites in the midguts of both pests. These results, together with the results from binding inhibition studies performed with sugars and lectins, indicated that Cry1Ac and Cry1Fa share some, but not all, binding sites, and that they were not shared with Cry1Ca or Cry2Aa in either soybean pest. This study contributes to the knowledge of Bt toxicity in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa Bt proteins as candidate proteins for Bt-pyramided crops.

scholarly journals Bacillus thuringiensis Cry34Ab1/Cry35Ab1 Interactions with Western Corn Rootworm Midgut Membrane Binding Sites

PLoS ONE ◽  
2013 ◽  
Vol 8 (1) ◽  
pp. e53079 ◽  
Author(s):  
Huarong Li ◽  
Monica Olson ◽  
Gaofeng Lin ◽  
Timothy Hey ◽  
Sek Yee Tan ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Binding Sites ◽  
Membrane Binding ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Membrane Binding Sites

scholarly journals Cross-Resistance of Cry1Ab-Selected Ostrinia nubilalis (Lepidoptera: Crambidae) to Bacillus thuringiensis δ-Endotoxins

2004 ◽  
Vol 97 (3) ◽  
pp. 1049-1057 ◽  
Author(s):  
Herbert A. A. Siqueira ◽  
Daniel Moellenbeck ◽  
Terence Spencer ◽  
Blair D. Siegfried
Keyword(s):  
Bacillus Thuringiensis ◽  
Ostrinia Nubilalis ◽  
Cross Resistance

scholarly journals Lead Optimization of Dehydroemetine for Repositioned Use in Malaria

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Priyanka Panwar ◽  
Kepa K. Burusco ◽  
Muna Abubaker ◽  
Holly Matthews ◽  
Andrey Gutnov ◽  
...  
Keyword(s):  
De Novo ◽  
Antimalarial Activity ◽  
Drug Repositioning ◽  
Multidrug Resistant ◽  
Cross Resistance ◽  
Synthetic Analogue ◽  
80S Ribosome ◽  
Content Type ◽  
Resistant Strains

ABSTRACT Drug repositioning offers an effective alternative to de novo drug design to tackle the urgent need for novel antimalarial treatments. The antiamoebic compound emetine dihydrochloride has been identified as a potent in vitro inhibitor of the multidrug-resistant strain K1 of Plasmodium falciparum (50% inhibitory concentration [IC50], 47 nM ± 2.1 nM [mean ± standard deviation]). Dehydroemetine, a synthetic analogue of emetine dihydrochloride, has been reported to have less-cardiotoxic effects than emetine. The structures of two diastereomers of dehydroemetine were modeled on the published emetine binding site on the cryo-electron microscopy (cryo-EM) structure with PDB code 3J7A (P. falciparum 80S ribosome in complex with emetine), and it was found that (−)-R,S-dehydroemetine mimicked the bound pose of emetine more closely than did (−)-S,S-dehydroisoemetine. (−)-R,S-dehydroemetine (IC50 71.03 ± 6.1 nM) was also found to be highly potent against the multidrug-resistant K1 strain of P. falciparum compared with (−)-S,S-dehydroisoemetine (IC50, 2.07 ± 0.26 μM), which loses its potency due to the change of configuration at C-1′. In addition to its effect on the asexual erythrocytic stages of P. falciparum, the compound exhibited gametocidal properties with no cross-resistance against any of the multidrug-resistant strains tested. Drug interaction studies showed (−)-R,S-dehydroemetine to have synergistic antimalarial activity with atovaquone and proguanil. Emetine dihydrochloride and (−)-R,S-dehydroemetine failed to show any inhibition of the hERG potassium channel and displayed activity affecting the mitochondrial membrane potential, indicating a possible multimodal mechanism of action.

scholarly journals The pinocytosis of 125I-labelled poly(vinylpyrrolidone), [14C]sucrose and colloidal [198Au]gold by rat yolk sac cultured in vitro

1977 ◽  
Vol 168 (2) ◽  
pp. 239-244 ◽  
Author(s):  
A V S Roberts ◽  
K E Williams ◽  
J B Lloyd
Keyword(s):  
Liquid Phase ◽  
Binding Sites ◽  
Substrate Concentration ◽  
Colloidal Gold ◽  
Membrane Binding ◽  
Yolk Sac ◽  
Free Medium ◽  
Membrane Binding Sites

The rates of uptake of 125I-labelled poly(vinylpyrrolidone), [14C]sucrose and colloidal [198Au]gold by 17.5-day rat yolk sac cultured in vitro were studied. Over a 6.5h period each substrate was accumulated at a constant and reproducible rate of approx. 2microliter/h per mg of protein. After accumulation in vitro, the three substances were released from the tissue into substrate-free medium at low rates. Sucrose present in the medium at concentrations up to 10 mg/ml was without effect on the accumulation of either [14C]sucrose or 125I-labelled poly(vinylpyrrolidone), but at higher concentrations inhibited the uptake of both substrates. Some batches of colloidal [198Au]gold had a significantly higher Endocytic Index (up to 5 microliter/h per mg of protein). The Endocytic Index of such a batch decreased with increasing substrate concentration, but colloidal gold did not decrease the Endocytic Index of 125I-labelled poly(vinylpyrrolidone). It is concluded that the three substrates enter the yolk sac by pinocytosis in the liquid phase. Those batches of colloidal [198Au]gold with higher Endocytic Indices are considered to enter also by adsorption on membrane binding-sites.

scholarly journals Role of putative membrane receptors in the effect of androgens on human vascular cell growth

2004 ◽  
Vol 180 (1) ◽  
pp. 97-106 ◽  
Author(s):  
D Somjen ◽  
F Kohen ◽  
B Gayer ◽  
T Kulik ◽  
E Knoll ◽  
...  
Keyword(s):  
Dna Synthesis ◽  
Binding Sites ◽  
Kinase Activity ◽  
Membrane Binding ◽  
Cell Types ◽  
Membrane Receptors ◽  
Vascular Cell ◽  
Mapk Kinase ◽  
High Concentrations ◽  
Membrane Binding Sites

We have reported previously that dihydrotestosterone (DHT) induces a biphasic effect on DNA synthesis in human vascular smooth muscle cells (VSMC), i.e. stimulation at low concentrations and inhibition at high concentrations. In contrast, DHT dose-dependently stimulated [(3)H]thymidine incorporation in a human endothelial cell line (ECV304). Additionally, DHT increased the specific activity of creatine kinase (CK) in both vascular cell types. In the present study, we have determined whether some of these effects are exerted via membrane-binding sites. We measured changes in DNA synthesis and CK after treatment with DHT and the membrane-impermeant testosterone-3-carboxymethyl oxime conjugated to bovine serum albumin (BSA) (T-BSA). High concentrations of either DHT or T-BSA inhibited VSMC proliferation (by 52+22% and 51+25% respectively). DHT as well as T-BSA increased DNA synthesis in ECV304 cells dose-dependently. In contrast, T-BSA did not affect CK in either cell type. In both cell types, DHT as well as T-BSA increased mitogen-activated protein kinase (MAPK) kinase activity as measured by total phosphorylated MAPK. Further, the inhibitory effect of either the free or protein-bound androgens on DNA synthesis was blocked by UO126, an inhibitor of MAPK kinase activity. T-BSA conjugate labeled with Europium showed binding to whole VSMC, which could be displaced by excess T-BSA, but not by estradiol-BSA or the free hormones. Finally, using T-BSA linked to the fluorescent dye Cy3.5, we directly demonstrated the presence of membrane-binding sites for androgen in VSMC. Hence, the inhibitory effects of testosterone on DNA synthesis in VSMC are apparently exerted by membrane-binding sites for androgen, do not require intracellular entry of the hormone and its binding to the classical nuclear receptors and are linked to MAPK activation.

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