Knockdown or inhibition of arginine kinases enhances susceptibility of Tribolium castaneum to deltamethrin

Crassostrea gigas peptide PEP-1 prevents tert-butyl hydroperoxide (t-BHP) induced oxidative stress in HepG2 cells

Exposure to tert-butyl hydroperoxide (t-BHP) leads to cytotoxicity and oxidative stress in various organs and cell types. The bioactive peptides extracted from Oysters exhibit marked antioxidant activity. The impacts of Crassostrea gigas peptides on t-BHP-triggered oxidative stress remain largely unknown. The protective and antioxidant activity of a C.gigas peptide, PEP-1, on t-BHP-treated HepG2 cells, was investigated. PEP-1, this peptide is arginine kinase in oysters. This enzyme functions as a catalyst for the chemical reaction and serves as a phosphate transferase. Since it was the most expressed protein in the adductor muscle of oysters. Our determination showed the lowest level of a toxic concentration of t-BHP (200 µM) and the resting concentration of PEP-1 (0-1000 ng/ml). PEP-1 exerted a protective effect against t-BHP-induced apoptosis by modifying the expression of pro-and anti-apoptotic proteins. PEP-1 administration reduced nitric oxide and ROS levels while restoring levels of antioxidant proteins in t-BHP-induced cells. PEP-1 exhibited the capacity to enhance the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2). Therefore, the C. gigas peptide PEP-1 has demonstrated its ability to protect HepG2 cells against oxidative stress induced by t-BHP.

Synergistic modes of interaction between the plant essential oils and the respiratory blocker chlorfenapyr

Plant essential oils are widely acknowledged for their insecticidal activities and synergistic interaction with conventional insecticides, but their insecticidal modes of action and the mechanism of synergy remain less understood. In this study, electrophysiological screenings on the larval central nervous system (CNS) of the common fruit fly, Drosophila melanogaster, and the housefly, Musca domestica, were conducted to identify the neurophysiological effects of the oils and their major constituents. Several oils changed the firing rate of the central motor neurons, and four oils were selected to determine their major active compounds. Eugenol and thymol (87.2% and 31.1% in clove bud and thyme oils, respectively) were inhibitory to the nerve firing rates of the CNS, and exhibited synergistic toxicity to the housefly when blended with a respiratory blocking pyrrole insecticide, chlorfenapyr. On the other hand, trans-cinnamaldehyde and terpinen-4-ol (74.6% and 52.0% in cinnamon and teatree oils) seemed excitatory to the nerves, and displayed antagonistic interaction to chlorfenapyr in their insecticidal activity. Chlorfenapyr led to ATP depletion in the insects, and the inhibitory compounds accelerated the process. On the other hand, nerve-excitatory compounds seemed to nullify the depletion. This was further confirmed with the two CNS-excitatory synthetic insecticides, permethrin and chlorpyrifos, that they exhibited antagonistic toxicity when mixed with chlorfenapyr. Meanwhile, the synergy between the inhibitory compounds and chlorfenapyr was diminished when ATP was artificially injected, indicating that the bioenergetic effects of neuroinhibitors are responsible for their synergistic interactions.

RNAi Mediated Gene Silencing of Detoxification Related Genes in the Ectropis oblique

Ectropis oblique is one of the main pests that feed on tea leaves. At present, the main control method is chemical control, but the long-term use of insecticides has been related to the development of insect resistance. One of the resistance mechanisms is the upregulation of relevant detoxification enzymes for defense. In this study, four genes with increased expression were screened from the gene sequences annotated from the transcriptome data of deltamethrin-treated larvae of E. oblique, which are acid phosphatase EoACP138, and cytochrome P450 EoCYP316, carboxylesterase EoCarE592 and acetylcholine esterase EoAchE989, respectively. The fourth instar larvae of E. oblique were stimulated by deltamethrin, chlorpyrifos and fenpropathrin respectively, and the expression levels of the genes were detected by qRT-PCR. The result showed that all four genes’ expression had significantly increased under the stimulation of three insecticides. RNAi technology was used to silence the expression of genes of EoACP138, EoCYP316, EoCarE592 and EoAchE989 in the fourth instar larvae of E. oblique. The change in the expression levels of the above genes in the larvae treated with dsRNA and stimulated with pesticides was determined by qRT-PCR. The target genes have been effectively silenced after feeding on dsRNA and higher sensitivity with higher mortality to pesticides was observed in the larvae interfered with dsRNA. The above genes are related to the detoxification and metabolism of resistance of E. oblique, which lays a foundation for further study on the mechanism of insecticide resistance in E. oblique.