Biochemical effect of carbaryl on oxidative stress, antioxidant enzymes and osmolytes of cyanobacterium Calothrix brevissima

Combined transcriptome and metabolite profiling analyses provide insights into the chronic toxicity of carbaryl and acetamiprid to Apis mellifera larvae

Despite many studies have revealed that developing honey bee (Apis mellifera) larvae are posting a high risk on exposure to insecticides, the toxicology information on bee larvae remain limited. The present study demonstrated the first assessment of the effects of no observed adverse effect concentration (NOAEC) of carbaryl (CR) and acetamiprid (ACE) on transcriptome and metabolome in honeybee larvae reared in vitro. Chronic exposure to carbaryl caused transcriptional disorders associated with oxidative stress. In addition, a series of metabolic homeostasis were disrupted by carbaryl stress, such amino acid metabolism, purine and pyrimidine metabolism and flavone and flavonol biosynthesis. The activities of enzymic biomarkers including GST, P450, CAT, AChE and SOD were not influenced by ACE stress, while the CR exposure slightly decreased the activity of CAT and SOD. Our results clearly show that ACE and CR display different potential to modulate transcriptome and metabolome associated with their different toxicity against bee larvae.

Mitigative effect of biosynthesized SeNPs on cyanobacteria under paraquat toxicity

Increasing population has resulted in increased food demand. Pesticides like paraquat (PQ) have been used indiscriminately to increase the growth and yield of crops. However, this has adversely affected a wide spectrum of non-target organisms like cyanobacteria that are used as a bio-fertilizer in the rice field. In the present study, biogenic- Gloeocaspa gelatinosa NCCU -430 mediated selenium nanoparticles (SeNPs) were synthesized and characterized using different techniques including UV-Visible spectroscopy, XRD, FTIR, TEM and SEM-EDX for their use as PQ toxicity mitigator in cyanobacterial biofertilizer (Anabaena variabilis NCCU-442). Therefore, a comparative study was performed among control, PQ, SeNPs and SeNPs+PQ to check the efficacy of SeNPs in mitigation of PQ induced toxicity. Supplementation of SeNPs in PQ treated culture enhanced antioxidant enzymes activity i.e., SOD (7.55%), CAT (57.94%), APX (17.45%) and GR (14.72%) as compared to only PQ treated culture. The outcomes of the present study suggested that SeNPs can ameliorate the PQ induced stress that may be used in sustainable rice cultivation needed for filing the gap between requirement and supply.

A Common Feature of Pesticides: Oxidative Stress-The Role of Oxidative Stress in Pesticide-Induced Toxicity

Pesticides are important chemicals or biological agents that deter or kill pests. The use of pesticides has continued to increase as it is still considered the most effective method to reduce pests and increase crop growth. However, pesticides have other consequences, including potential toxicity to humans and wildlife. Pesticides have been associated with increased risk of cardiovascular disease, cancer, and birth defects. Labels on pesticides also suggest limiting exposure to these hazardous chemicals. Based on experimental evidence, various types of pesticides all seem to have a common effect, the induction of oxidative stress in different cell types and animal models. Pesticide-induced oxidative stress is caused by both reactive oxygen species (ROS) and reactive nitrogen species (RNS), which are associated with several diseases including cancer, inflammation, and cardiovascular and neurodegenerative diseases. ROS and RNS can activate at least five independent signaling pathways including mitochondrial-induced apoptosis. Limited in vitro studies also suggest that exogenous antioxidants can reduce or prevent the deleterious effects of pesticides.

Protective Responses Induced by Chiral 3-Dichloroacetyl Oxazolidine Safeners in Maize (Zea mays L.) and the Detoxification Mechanism

Herbicide safeners selectively protect crops from herbicide injury while maintaining the herbicidal effect on the target weed. To some extent, the detoxification of herbicides is related to the effect of herbicide safeners on the level and activity of herbicide target enzymes. In this work, the expression of the detoxifying enzyme glutathione S-transferase (GST) and antioxidant enzyme activities in maize seedlings were studied in the presence of three potential herbicide safeners: 3-dichloroacetyl oxazolidine and its two optical isomers. Further, the protective effect of chiral herbicide safeners on detoxifying chlorsulfuron in maize was evaluated. All safeners increased the expression levels of herbicide detoxifying enzymes, including GST, catalase (CAT), and peroxidase (POD) to reduce sulfonylurea herbicide phytotoxicity in maize seedlings. Our results indicate that the R-isomer of 3-(dichloroacetyl)-2,2,5-trimethyl-1,3-oxazolidine can induce glutathione (GSH) production, GST activity, and the ability of GST to react with the substrate 1-chloro-2,4-dinitrobenzene (CDNB) in maize, meaning that the R-isomer can protect maize from damage by chlorsulfuron. Information about antioxidative enzyme activity was obtained to determine the role of chiral safeners in overcoming the oxidative stress in maize attributed to herbicides. The interaction of safeners and active target sites of acetolactate synthase (ALS) was demonstrated by molecular docking modeling, which indicated that both isomers could form a good interaction with ALS. Our findings suggest that the detoxification mechanism of chiral safeners might involve the induction of the activity of herbicide detoxifying enzymes as well as the completion of the target active site between the safener and chlorsulfuron.

High Skp2 expression is associated with a mesenchymal phenotype and increased tumorigenic potential of prostate cancer cells

Skp2 is a crucial component of SCFSkp2 E3 ubiquitin ligase and is often overexpressed in various types of cancer, including prostate cancer (PCa). The epithelial-to-mesenchymal transition (EMT) is involved in PCa progression. The acquisition of a mesenchymal phenotype that results in a cancer stem cell (CSC) phenotype in PCa was described. Therefore, we aimed to investigate the expression and localization of Skp2 in clinical samples from patients with PCa, the association of Skp2 with EMT status, and the role of Skp2 in prostate CSC. We found that nuclear expression of Skp2 was increased in patients with PCa compared to those with benign hyperplasia, and correlated with high Gleason score in PCa patients. Increased Skp2 expression was observed in PCa cell lines with mesenchymal and CSC-like phenotype compared to their epithelial counterparts. Conversely, the CSC-like phenotype was diminished in cells in which SKP2 expression was silenced. Furthermore, we observed that Skp2 downregulation led to the decrease in subpopulation of CD44+CD24- cancer stem-like cells. Finally, we showed that high expression levels of both CD24 and CD44 were associated with favorable recurrence-free survival for PCa patients. This study uncovered the Skp2-mediated CSC-like phenotype with oncogenic functions in PCa.

Comparative studies on growth and physiological responses of unicellular and colonial Microcystis aeruginosa to Acorus calamus

In order to explore the growth inhibition and physiological responses of unicellular and colonial Microcystis aeruginosa during coexistence with Acorus calamus, algal densities, chlorophyll a contents, exopolysaccharide (EPS) concentrations, malondialdehyde (MDA) contents, catalase (CAT) activities, and peroxidase (POD) activities of the two algae strains were analyzed. Although the unicellular and colonial strains of M. aeruginosa were both inhibited by A. calamus, unicellular algae were more sensitive than the colonial algae. The measurement results for EPS, MDA, CAT, and POD showed that unicellular M. aeruginosa had higher levels of stress related damage than colonial strains when they were exposed to the same density of A. calamus, and the cellular defense system of colonial M. aeruginosa was stronger than that of unicellular M. aeruginosa. Natural blooms of Microcystis are typically composed of colonial forms of M. aeruginosa, therefore future efforts to control such blooms, possibly through the development of new algicides, should focus on the unique characteristics of colonial M. aeruginosa strains.

Effect of cadmium on biomass, pigmentation, malondialdehyde, and proline of Scenedesmus quadricauda var. longispina

Effects of cadmium (Cd(2+)) on biomass, pigmentation (chlorophyll a, b, and total carotene), malondialdehyde (MDA), and proline productions by Scenedesmus quadricauda var. longispina were investigated. Cadmium had inhibitory effect on the productions of biomass and pigmentation. Significant differences were found in pigment content among groups. On the other hand, Cd(2+) had a simulative effect on the production of MDA and proline by the alga. FTIR-ATR spectroscopy was used to examine active groups of algal biomass before and after Cd(2+) exposure. Results confirmed that amino, amide, and anionic groups had significant role on the biosorption of Cd(2+) by the alga. Increased accumulation of MDA and proline seemed to be an important strategy for alleviating metal-induced oxidative stress in S. quadricauda var. longispina.

Combined exposure to cyanobacteria and carbaryl results in antagonistic effects on the reproduction of Daphnia pulex

In aquatic ecosystems, Daphnia are exposed to a wide variety of natural and chemical stressors that can cause interactive effects resulting in an increased impact on aquatic ecosystems. The authors therefore investigated the interactive effects of harmful cyanobacteria (cyanoHABs) with carbaryl in Daphnia pulex, because cyanobacteria have become an important concern for aquatic ecosystems. Daphnia were exposed for 21 d to 4 selected cyanobacteria (Aphanizomenon sp., Cylindrospermopsis raciborskii, Microcystis aeruginosa, and Oscillatoria sp), carbaryl, and all binary combinations of carbaryl and each individual cyanobacterium. Results were analyzed with both the independent action and the concentration addition model. The estimated median effect concentration (EC50) for carbaryl was comparable between the experiments, ranging from 2.28 µg/L to 5.94 µg/L. The EC50 for cyanobacteria ranged from 13.45% of the total diet ratio for Microcystis to 66.69% of the diet ratio for Oscillatoria. In combination with carbaryl, the response of Daphnia to 3 of the 4 cyanobacteria demonstrated antagonistic deviation patterns (p < 0.05). Exposure to combinations of carbaryl and Cylindrospermopsis did not result in statistically significant deviations from both reference models. The results may have important implications for pesticide risk assessment, underlining the impact of interactive effects on aquatic organisms. Based on these results, the authors suggest that both the independent action and the concentration addition model can serve as a protective approach in risk assessment of carbaryl in the presence of cyanobacterial blooms.

Carbaryl stress induced cellular changes in Calothrix brevissima

Cyanobacterial biofertilizers are affected by paddy field pesticides as nontarget organism. Carbaryl is a carbamate pesticide and is commonly used against rice thrip pest in paddy fields. In the present work, cellular changes caused by exposure of the cyanobacterial biofertilizer namely Calothrix brevissima to carbaryl were studied with special reference to fatty acids, electrolyte leakage, sulfur metabolism, and osmolytes. To study the toxic effect of carbaryl, the test cyanobacterium was exposed to varying concentrations of pesticide (0, 10, 20, 30, and 40 mg L(-1)) for biochemical analyses. At 40 mg L(-1) carbaryl, polyunsaturated fatty acids were reduced by 32 % and membrane leakage was increased by 27 % suggesting that free radical-mediated lipid peroxidation took place. The sulfur-containing metabolites namely cysteine, cystine, and methionine were increased by 79, 64, and 52 %, respectively. The enzymatic and nonenzymatic antioxidants namely glutathione S-transferase, glutathione reductase, reduced glutathione, and oxidized glutathione were increased to 56, 71, 72, and 60 %, respectively. Osmolytes that serve as stress enzyme protectors as well as nonenzymatic free radical scavenger were also increased, indicating their protective nature in context with carbaryl-induced stress. The respective increase in mannitol, trehalose, and glycogen were 158, 98, and 159 %. In C. brevissima, carbaryl-induced membrane leakage was counteracted by increasing enzymatic and nonenzymatic parameters that helped in scavenging free radicals.