Influence of bacillus thuringiensis toxins on the development and midgut proteases in different larval instars of helicoverpa armigera

Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) is one of the most important pest worldwide. Bacillus thuringiensis (Bt) toxins have used as a biopesticide or deployed in transgenic plants for controlling this pest. We examined the biological activity of Cry1Ac, Cry1Ab and Bt formulation in different larval instars of H. armigera with respect to larval development and proteolytic activity to pinpoint the most susceptible instar, and the insect response to ingestion of Bt toxins. In the presence of Bt toxins, the larval mortality and weight loss increased in a dose-dependent manner, and the maximum effect was observed in neonates. Active Cry1Ac toxin resulted in greater mortality and weight loss in all the larval instars. Total protease, trypsin and chymotrypsin activities declined in the presence of Bt toxins as compared to the untreated control in all the larval instars. Ten protease isozymes were observed in the untreated control larvae in second, third and fourth instars. Maximum protease isozymes inhibition was observed in Bt toxin fed neonates. Inhibition of protease activity increased with the concentration of Bt toxins. In presence of Bt toxins, aminopeptidase activity increased from II to IV instar and alkaline phosphatase activity decreased from II to III and then increased in IV instar. The pathogenicity of Bt was greater in early larval instars of H. armigera than the later instars, suggesting that application of Bt formulation or deployment of Bt toxins in transgenic plants should be directed against the early larval instars

Elimination of Gut Microbes with Antibiotics Confers Resistance to Bacillus thuringiensis Toxin Proteins in Helicoverpa armigera (Hubner)

Helicoverpa armigera is one of the most important pests worldwide. Transgenic crops with toxin genes from Bacillus thuringiensis (Bt) have been deployed on a large scale to control this pest. The insecticidal activity of Bt is probably influenced by the insect midgut microbes, which vary across crop hosts and locations. Therefore, we examined the role of gut microbes in pathogenicity of Bt toxins in the H. armigera. Antibiotic cocktail was used for the complete elimination of the H. armigera gut microbes. Activated Cry1Ac, Bt formulation, and transgenic cotton resulted in larval weight loss and increase in mortality, but pretreatment of larvae with antibiotic cocktail significantly decreased larval mortality and increased the larval weight gain. Activated Cry1Ac and Bt formulation inhibited the activity of proteases in midgut of H. armigera larvae but showed no such effect in the larvae pretreated with antibiotic cocktail. Five protease bands in activated Cry1Ac and two in Bt formulation-treated larvae were inhibited but no such effect in the larvae pretreated with antibiotic cocktail. Cry1Ac protein was detected in Bt/Cry1Ac protoxin-fed larval gut extract in the absence of antibiotic cocktail, but fewer in larvae pretreated with antibiotic cocktail. The activity of antioxidant enzymes and aminopeptidases increased in larvae fed on Bt toxin, but there was no significant increase in antioxidant enzymes in larvae reared on toxin protein in combination with antibiotic cocktail. The results suggest that gut microbes exercise a significant influence on the toxicity of Cry1Ac and Bt formulation in H. armigera larvae. The implications of these results have been discussed in relation to development of insect resistance to Bt transgenic crops deployed for pest management

An environment-friendly approach to produce nanostructured germanium anodes for lithium-ion batteries

International audienceIn this paper, we propose a halogen-free process for the preparation of germanium micro-scale particles with a nano-structured surface morphology from germanium citrate, an easily accessible and environment-friendly precursor formed from germanium dioxide and citric acid in an aqueous medium. Electrodeposition of nanostructured Ge anodes on copper foil was performed via electrolysis of 1-5% germanium citrate solution in propylene glycol with addition of 5% acetic acid. Cyclic voltammetry data suggested that germanium citrate is an electrochemically inactive compound, but readily undergoes reduction by cathodic hydrogen released in the electrolysis. Such behaviour allows one to run the electrolysis under simple galvanostatic conditions without any need for controlling the potential. Furthermore, no diaphragm is required to separate the cathodic and anodic cell compartments. The electrodeposition produces black and compact films composed of similar to 200 nm germanium particles, which, in turn, consist of nanoparticles no larger than 25 nm in size (SEM and TEM data). XRD and Raman spectroscopy data lead to the conclusion that germanium precipitates in the amorphous phase; however, with an increase in the power of the He-Ne laser (632.8 nm) during Raman spectra recording, it transforms into a nanocrystalline form. Testing germanium anodes in lithium-ion half-cells showed a specific capacity of similar to 600 mA h g(-1) at 1-2C current rates, which is comparable to the best results achieved for Ge anodes produced using more sophisticated and less environment-friendly techniques

Gene Therapy with Etranacogene Dezaparvovec for Hemophilia B

Background: Moderate-to-severe hemophilia B is treated with lifelong, continuous coagulation factor IX replacement to prevent bleeding. Gene therapy for hemophilia B aims to establish sustained factor IX activity, thereby protecting against bleeding without burdensome factor IX replacement. Methods: In this open-label, phase 3 study, after a lead-in period (≥6 months) of factor IX prophylaxis, we administered one infusion of adeno-associated virus 5 (AAV5) vector expressing the Padua factor IX variant (etranacogene dezaparvovec; 2×1013 genome copies per kilogram of body weight) to 54 men with hemophilia B (factor IX activity ≤2% of the normal value) regardless of preexisting AAV5 neutralizing antibodies. The primary end point was the annualized bleeding rate, evaluated in a noninferiority analysis comparing the rate during months 7 through 18 after etranacogene dezaparvovec treatment with the rate during the lead-in period. Noninferiority of etranacogene dezaparvovec was defined as an upper limit of the two-sided 95% Wald confidence interval of the annualized bleeding rate ratio that was less than the noninferiority margin of 1.8. Superiority, additional efficacy measures, and safety were also assessed. Results: The annualized bleeding rate decreased from 4.19 (95% confidence interval [CI], 3.22 to 5.45) during the lead-in period to 1.51 (95% CI, 0.81 to 2.82) during months 7 through 18 after treatment, for a rate ratio of 0.36 (95% Wald CI, 0.20 to 0.64; P<0.001), demonstrating noninferiority and superiority of etranacogene dezaparvovec as compared with factor IX prophylaxis. Factor IX activity had increased from baseline by a least-squares mean of 36.2 percentage points (95% CI, 31.4 to 41.0) at 6 months and 34.3 percentage points (95% CI, 29.5 to 39.1) at 18 months after treatment, and usage of factor IX concentrate decreased by a mean of 248,825 IU per year per participant in the post-treatment period (P<0.001 for all three comparisons). Benefits and safety were observed in participants with predose AAV5 neutralizing antibody titers of less than 700. No treatment-related serious adverse events occurred. Conclusions: Etranacogene dezaparvovec gene therapy was superior to prophylactic factor IX with respect to the annualized bleeding rate, and it had a favorable safety profile