Exogenous nanoselenium alleviates imidacloprid-induced oxidative stress toxicity by improving phenylpropanoid metabolism and antioxidant defense system in Perilla frutescens (L.) Britt

Few studies have been conducted to investigate the impact of pesticides on the secondary metabolism of traditional Chinese medicine and strategies to mitigate the toxicity of pesticide-induced oxidative stress. The current study focuses on evaluating the potential impacts of nano selenium (NSe) and imidacloprid (IMI) on the quality, physiological biochemistry, and secondary metabolites in Perilla frutescens (L.) Britt. (P. frutescens). The study utilized metabolome analysis to explore the toxicity mechanism of IMI. The study noted that IMI-induced stress could emerge with detrimental effects by targeting the destruction of the phenylpropanoid biosynthesis pathway. IMI-induced phenylpropanoid metabolism disorder resulted in an 8%, 17%, 25%, 10%, 65%, and 29% reduction in phenylalanine, coniferyl aldehyde, ferulic acid, cafestol, p-coumaraldehyde, and p-coumaric acid levels, respectively. Under the treatment of exogenous NSe, the levels of these metabolites were increased by 16%, 32%, 22%, 22%, 92%, and 29%, respectively. The application of exogenous NSe increased the levels of these metabolites and improved the biochemical disorder and quality of P. frutescens leaves by optimizing the phenylpropanoid metabolic pathway and enhancing the antioxidant system. Overall, the results suggest that foliar application of NSe could alleviate the oxidative stress toxicity induced by IMI and improve the quality of P. frutescens.

Role of the tyrosine aminotransferase AccTATN gene in the response to pesticide and heavy metal stress in Apis cerana cerana

Tyrosine aminotransferase (TATN) is the first enzyme involved in the metabolic degradation of tyrosine, and it plays an important role in tyrosine detoxification and helps the body resist oxidative damage. However, the function of TATN in Apis cerana cerana (A. c. cerana) remains unclear. To explore the role of TATN in the response to pesticide and heavy metal stress in A. c. cerana, AccTATN was isolated and identified. AccTATN was highly expressed in the integument and the adult stage. Exposure to multiple pesticides and heavy metal stress upregulated AccTATN expression. RNA interference experiments showed that silencing AccTATN reduced the resistance of A. c. cerana to glyphosate and avermectins stress. The expression of antioxidant-related genes and the activity of antioxidant enzymes were reduced after AccTATN was silenced, leading to the accumulation of oxidative damage. Overexpression of the recombinant AccTATN protein in a prokaryotic system also confirmed its role in heavy metal stress and improved antioxidant capacity. Our study showed that AccTATN may promote resistance to pesticide and heavy metal stress by regulating the antioxidant capacity of A. c. cerana. This study provides a valuable theoretical basis for A. c. cerana conservation.

Antioxidant enzymatic activities and profiling of gene expression associated with organophosphate stress tolerance in Solanum melongena L.cv. Longai

The tolerance mechanism of chemical pesticide is necessary to combat the pest infestation challenges. This study intended to analyze the responses of enzymatic activity and expression level of an antioxidant gene to organophosphate pesticide stress. The alteration of anti-oxidative correlated with pesticide treatment in eggplant (S. melongena L.cv. Longai) using varying concentrations (0, 50, 100, 150 and 200 ppm) of malathion (PM) and tatafen (PTF) each. The enzyme activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were observed to be elevated with pesticide treatment in eggplant seedling. FeSOD (iron SOD), CAT and APX genes associated in defense mechanisms were significantly expressed under PM and PTF stress which contributed to stress tolerance to the plant. The different concentration of both pesticide stresses altered the expression level of mRNA, FeSOD, CAT and APX genes in comparison to the non-treated plant. While mRNA level of three antioxidant genes were evaluated and found to be APX gene expression was more potent than the CAT and FeSOD gene subjected to different concentrations of PM and PTF in eggplant. The current experiment highlights the presence of minimum level of pesticide concentration impacted positively towards the plant growth and metabolism, while high level of pesticide concentration impacted negatively. In summary, antioxidant enzymes activity responded to both pesticide stresses at an early stage of exposure and their gene expression profiles provided more details about their complex interaction and effectively scavenge reactive oxygen species. This allows the plant to maintain growth under pesticide stress.

Nanoselenium foliar application enhances biosynthesis of tea leaves in metabolic cycles and associated responsive pathways

An emerging stress of pesticides in plant and soil is closely watched as it affects crop antioxidant systems, nutritional quality, and flavor. Although selenium (Se) can enhance the resistance of plants, the protective mechanism of nanoselenium is still not known under the long-term pesticide stress in tea trees. In this study, we investigated the potential effects of foliar application of nanoselenium for a two-year field experiment on tea plants under pesticide-induced oxidative stress. Compared to control, nano-Se (10 mg/L) markedly enhanced the protein, soluble sugar, carotenoid, tea polyphenols, and catechins contents. High levels of theanine, glutamic acid, proline, and arginine were found to be induced most likely by adjusting the GS-GOGAT cycle. Se-supplementation may promote tea leaves' secondary metabolism, thus increasing the accumulation of total phenols and flavonoids (apigenin, kaempferol, quercetin, myricetin, and rutin). It also minimized the accumulation of malondialdehyde, hydrogen peroxide, and superoxide anion by activating the antioxidants enzymes including in the AsA-GSH cycle. Selenium-rich tea also showed better fragrance and flavor. In summary, nano-Se can ameliorate the nutrients quality and abiotic stresses resistance of crops.

Molecular characterization, expression and enzyme activity of three glutathione S-transferase genes from Eriocheir sinensis under pesticide stresses

Glutathione S-transferases (GSTs) are a multifunctional protein superfamily that can catalyze the detoxification processes in an organism. In the present study, we determined the structure and function of GSTs in Chinese mitten crab (Eriocheir sinensis) by gene cloning, expression, and enzyme activity in order to investigate the metabolic detoxification of GSTs in the hepatopancreas and muscles under three pesticide (trichlorfon, β-cypermethrin and avermectin) stresses. Multiple sequence alignment analysis showed that all the three Es-GST genes possessed N-terminal, and C-terminal domain as well as G-binding sites, while Es-GST2 and Es-GST3 contained Mu-type GST-specific Mu-loop structures. Phylogenetic tree analysis revealed that the three Es-GSTs belonged to the Mu-type GST of crustaceans. The quantitative real-time PCR revealed that the three Es-GSTS were expressed in 9 tissues of Eriocheir sinensis, with highest expression in hepatopancreas and muscle. The expression of the three Es-GSTS significantly increased in the hepatopancreas and muscle under the three pesticide stresses compared to the control group, and a steady increase in GST activity was observed. The study showed that the three Es-GSTs belong to the Mu-type GST of the crustaceans and might play an important role in the metabolic detoxification in Eriocheir sinensis.

Cu/ZnSOD always responded stronger and rapider than MnSOD in Lymantria dispar larvae under the avermectin stress

Metalloenzyme SODs play important roles in insects dealing with environmental stress. Here, we cloned the Cu/ZnSOD (LdCZS) and MnSOD (LdMS) mRNA of Lymantria dispar by rapid amplification of cDNA ends (RACE). Afterwards their expression patterns were detected by quantitative real-time polymerase chain reaction (qPCR) after bioinformatic analysis. We found that both LdCZS and LdMS were widely detected in all gypsy moth larvae and all five tissues that we analyzed, and both of them were up-regulated after larvae were fed with avermectin of sublethal concentration and LC₁₀. The LdCZS expression value are always higher than LdMS after treating with avermectin of sublethal concentrations. In addition, temporal expression profile in avermectin treated larvae showed that LdCZS expressed highest at 2nd hour, and LdMS expressed highest at 6th hour. The cuticulas transcribed LdCZS and LdMS significantly higher than heads, fat bodies, Malpighian tubes, and midguts after spraying avermectin of sublethal concentration. These results suggested that both Cu/ZnSOD and MnSOD are important antioxidant enzymes in L. dispar defensing against pesticide stress, and LdCZS always responded rapider and stronger than LdMS.

Mechanisms of compensatory dynamics in zooplankton and maintenance of food chain efficiency under toxicant stress

Communities with species that are tolerant to environmental stresses may be able to maintain the ecosystem functions under the stress, because the tolerant species can compensate for the loss of sensitive species. In this study, we focused on the food chain efficiency (FCE), the trophic transfer across three trophic levels, as an important process for ecosystem function, and examined the conditions under which such compensation could occur with aquarium experiments using an insecticide (methomyl) as the stressor. Our aquariums included one of two pairs of insecticide-tolerant and insecticide-sensitive cladoceran species, and a fish as the predator. The response of FCE to the insecticide stress, as indicated by the fish biomass production, depended on the zooplankton species combinations. FCE and total zooplankton biomass were maintained in the pair in which the compensatory changes of species abundances were clear, whereas they decreased in the pair in which the compensatory changes were not clear. This indicated the compensatory dynamics in the zooplankton community responsible for the observed resistance to the stress. We inferred the driving factors for the compensatory dynamics and the community resistance with respect to species traits of ecological importance, and concluded that a dissimilarity between species as regards the tolerance trait and a clear trade-off between the tolerance and the competitive ability was required to drive the compensatory dynamics, and a similarity or a superiority of the tolerant species as regards the functional effect trait (the predator avoidance and the reproductive potential) were required to maintain FCE.