Evaluation of insecticidal potential of organochemicals on SF9 cell line

Background Organophosphates and Pyrethroids are the most widely used pesticides worldwide and are known to have significant toxicity on the nervous system of the target pest. Assessment for combined toxicity of Organophosphate and Pyrethroid on Sf9 (Spodoptera frugiperda) cells is less explored. The present study demonstrates and compares the two organochemicals whose trade names are Ammo and Profex, for its cytotoxic potential on the insect Sf9 cells. Ammo and Profex were selected as the test chemicals as toxicity of these insecticides at molecular and cellular level is poorly understood. Results The results of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay demonstrated that Ammo and Profex exhibited significant cytotoxicity to Sf9 cells in a time- and dose-dependent manner. In our study, the IC50 value was obtained by MTT assay and the sub-lethal concentrations (IC50/20-17.5 µg/ml, IC50/10-35 µg/ml, and IC50/5–70 µg/ml for Ammo and IC50/20-20 µg/ml, IC50/10-40 µg/ml, and IC50/5-80 µg/ml for Profex) were selected for further tests. Acridine orange/ethidium bromide staining proved the apoptotic cell death on exposure of both the insecticides confirming its toxic potential. Furthermore, antioxidant status was assessed using DCF-DA staining and both the insecticides resulted into an increased reactive oxygen species (ROS) generation. A dose- and time-dependent significant (p < 0.05) alterations in lipid peroxidase (LPO), glutathione (GSH) and catalase (CAT) activity were observed. Conclusion The results showed that both Ammo and Profex triggered apoptosis in Sf9 cells through an intrinsic mitochondrial pathway via the generation of ROS. Of the two insecticides, Ammo was found to be more toxic compared to Profex. The present study is important to evaluate the environmental safety and risk factors of Organochemicals’ exposure to crops and livestock.

Structure–Activity Relationship of Phytotoxic Natural 10-Membered Lactones and Their Semisynthetic Derivatives

Ten-membered lactones (nonenolides) demonstrate phytotoxic, antimicrobial, and fungicidal activity promising for the development of natural product-derived pesticides. The fungus Stagonospora cirsii is able to produce phytotoxic stagonolides A (1), J (2), K (3) and herbarumin I (4) with high yield. The aim of this study was to create a set of structurally related nonenolides and to reveal the structural features that affect their biological activity. Stagonolide A (1) and C-7 oxidized stagonolide K (11) showed the highest phytotoxicity in leaf puncture assay and agar seedlings assay. The oxidation of C-7 hydroxyl group (as in 1, acetylstagonolide A (10) and (11) led to the manifestation of toxicity to microalgae, Bacillus subtilis and Sf9 cells regardless of the configuration of C-9 propyl chains (R in 1 and 10, S in 11). C-7 non-oxidized nonenolides displayed none or little non-target activity. Notably, 7S compounds were more phytotoxic than their 7R analogues. Due to the high inhibitory activity against seedling growth and the lack of side toxicity, mono- and bis(acetyl)- derivatives of herbarumin I were shown to be potent for the development of pre-emergent herbicides. The identified structural features can be used for the rational design of new herbicides.

Insight Into Cellular Uptake and Transcytosis of Peptide Nanoparticles in a Generalist Caterpillar.

Development of novel and specific insect pest management methods is critical for overcoming pesticide resistance and off-target effects. Gene silencing through consumption of double stranded (dsRNA) by insects shows promise in this area. Association of dsRNA with nanoparticles confers protection against nucleases, and can also promote translocation of dsRNA across the midgut epithelial cell membranes, and overall enhance gene knockdown effects. However, many mysteries of how nanoparticles and dsRNA are internalized by cells and subsequently transported across the midgut epithelium remain to be unraveled. In this article, we investigate the role of endocytosis and transcytosis in the uptake and transport of dsRNA and nanoparticles through midgut epithelium cells. Spodoptera frugiperda (Sf9) cells and branched amphiphilic peptide nano-capsules (BAPCs) were used as an experimental model. Additionally, analyses of reactive oxygen and nitrogen species (ROS/RNS) were performed to demonstrated that cell viability was minimally impacted by the BAPCs-dsRNA complex. Results suggests that clathrin-mediated endocytosis and macropinocytois are largely responsible for cellular uptake, and once within the midgut, transcytosis is involved in shuttling BAPCs from the lumen to the hemolymph. BAPCs were not found to be toxic to Sf9 cells or generate damaging reactive species once internalized. This opens up further possibilities for BAPCs as a new insect pest management method.

Bombyx mori β1,4-N-acetylgalactosaminyltransferase possesses relaxed donor substrate specificity in N-glycan synthesis

N-Glycosylation is one of the most important post-translational protein modifications in eukaryotic cells. Although more than 200 N-glycogenes contributing to N-glycan biosynthesis have been identified and characterized, the information on insect N-glycosylation is still limited. Here, focusing on insect N-glycosylation, we characterized Bombyx mori N-acetylgalactosaminyltransferase (BmGalNAcT) participating in complex N-glycan biosynthesis in mammals. BmGalNAcT localized at the Golgi and was ubiquitously expressed in every organ and in the developmental stage of the middle silk gland of fifth instar larvae. Analysis of recombinant BmGalNAcT expressed in Sf9 cells showed that BmGalNAcT transferred GalNAc to non-reducing terminals of GlcNAcβ1,2-R with β1,4-linkage. In addition, BmGalNAcT mediated transfer of galactose and N-acetylglucosamine residues but not transfer of either glucose or glucuronic acid from the UDP-sugar donor substrate to the N-glycan. Despite this tri-functional sugar transfer activity, however, most of the endogenous glycoproteins of insect cells were present without GalNAc, Gal, or GlcNAc residues at the non-reducing terminal of β1,2-GlcNAc residue(s). Moreover, overexpression of BmGalNAcT in insect cells had no effect on N-acetylgalactosaminylation, galactosylation, or N-acetylglucosaminylation of the major N-glycan during biosynthesis. These results suggested that B. mori has a novel multifunctional glycosyltransferase, but the N-glycosylation is highly and strictly regulated by the endogenous N-glycosylation machineries.

Popularizing recombinant baculovirus-derived OneBac system for laboratory production of all recombinant adeno-associated virus vector serotypes

Objective: On the basis of our previously established single recombinant baculovirus expression vector (BEV)-derived OneBac system, we have optimized the process and expanded the rAAV production range to the full range of serotypes rAAV1-13. Firstly, the AAV Cap gene was optimized to translate by ribosome leaky scanning and the gene of interest (GOI) was cloned into the pFD/Cap-(ITR-GOI)-Rep2 shutte plasmid. Following the classical Bac-to-Bac method, sufficient BEV stock containing all rAAV packaging elements can be quickly obtained. Finally, we can repeatedly scale up production of rAAVs in one week by using a single BEV to infect suspension-cultured Sf9 cells. The rAAV1-13 show relatively high yields ranging from 5×104 to 4×105 VG/cell. More than 1×1015 VG purified rAAVs can be easily obtained from 5 L suspension-cultured Sf9 cells. As expected, rAAV serotypes 1-13 show different potencies for in vitro transduction and celltype tropisms. Background: Recombinant adeno-associated virus (rAAV) has been widely used as an efficient transgenic vector in biomedical research, as well as gene therapy. Serotype-associated transduction efficiency, tissue- or cell-type tropism and immunological profile are major considerations in the various applications of rAAVs. There are increasing needs for different serotypes of rAAV, either naturally isolated or artificially engineered. However, affordable and scalable production of a desired serotype of rAAV remains very difficult, especially for researchers lacking relevant experience. Conclusion: In summary, the single BEV-derived OneBac system should prove popular for laboratory scaling-up production of any serotype of rAAV.

Simple and rapid plaque assay for recombinant baculoviruses expressing influenza hemagglutinin

Recombinant baculoviruses (rBVs) have been extensively used to generate virus-like particles, and baculoviruses expressing antigenic proteins have become efficient tools for inducing protective immunity. However, current methods for generating baculoviruses are costly and inefficient. Thus, the development of a simple, rapid, and accurate method of baculovirus titration is critically important. We established a method of plaque assay using an immunostaining method by which plaques can be easily visualized in Sf9 cells under a light microscope. Sf9 cells were infected with recombinant baculoviruses expressing influenza hemagglutinin surface proteins from H1N1 (A/California/04/09) or rH5N1 (A/Vietnam/1203/04). The infected cells were incubated with anti-HA antibody and the plaques were visualized using the chromogen 3′3-diaminobenzidine (DAB). Plaques were observed from days 1 to 6 post-infection, and differences in Sf9 cell seeding densities resulted in variations in the final plaque quantification. Sf9 cells seeded at a concentration of 5.5 × 104 cells/well or 7.5 × 104 cells/well showed the higher plaque titers at days 3, 4, and 5 post-infection than those found at days 1, 2, and 6 post-infection. With 5.5 × 104 cells/well or 7.5 × 104 cells/well of cell concentrations, recombinant baculovirus for rBV-HA (H1N1) showed 6 × 107 pfu/ml of titer and rBVs for rBV-HA (rH5N1) showed 5.4 × 107 pfu/ml of titer. Three days of baculovirus incubation with a certain concentration of Sf9 cells seeded are required for a rapid, simple, and accurate plaque assay, which could significantly contribute to all baculovirus-related studies.