Triazophos-induced oxidative stress and histomorphological changes in ovary of female Wistar rats

Synergistic risk in the gut and liver: Insights into the toxic mechanisms and molecular interactions of combined exposure to triazophos and fenvalerate in zebrafish

The simultaneous or sequential application of pesticides such as triazophos (TRI) and fenvalerate (FEN) in agriculture results in their residues co-existing in the environments. However, the impact of co-exposure to TRI and FEN on the gut-liver axis, along with the underlying mechanisms, remains unclear. Our results showed that exposure to FEN (96 h-LC50 value of 0.096 mg a.i. L-1) was more toxic to adult zebrafish compared to TRI (96 h-LC50 value of 6.75 mg a.i. L-1). Furthermore, the study aimed to reveal the toxic potencies of individual and combined exposure to TRI and FEN on the liver-gut axis in zebrafish (Danio rerio). Our results also indicated that pesticide exposure decreased tight junction molecule expression and increased intestinal inflammatory molecule expression in D. rerio, with co-exposure demonstrating enhanced toxicity. Co-exposure altered gut flora structure and species abundance. RNA-Seq sequencing revealed changes in liver gene expressions, particularly enrichment of P53 signaling. Molecular docking demonstrated FEN's stronger binding to P53 and Caspase3, correlating with its higher toxicity. Liver pathology confirmed exacerbated liver damage by individual and co-exposures, with co-exposure inducing more severe liver injury. qPCR results showed increased pro-apoptotic gene expression and decreased anti-apoptotic gene expression, with co-exposure exhibiting an interactive effect. Overall, this study identifies specific targets and pathways influenced by these pesticides, revealing toxicity mechanisms involving the gut-liver axis, which is crucial for environmental risk assessment of pesticide mixtures.

Co-exposure to cadmium and triazophos induces variations at enzymatic and transcriptional levels in Opsariichthys bidens

Heavy metals and pesticides are significant pollutants in aquatic environments, often leading to combined pollution and exerting toxic effects on aquatic organisms. With the rapid growth of modern industry and agriculture, heavy metal cadmium (Cd) and pesticide triazophos (TRI) are frequently detected together in various water bodies, particularly in agricultural watersheds. However, the combined toxic mechanisms of these pollutants on fish remain poorly understood. This experiment involved a 21-day co-exposure of Cd and TRI to the hook snout carp Opsariichthys bidens to investigate the toxic effects on liver tissues at both enzymatic and transcriptional levels. Biochemical analysis revealed that both individual and combined exposures significantly increased the content or activity of caspase-3 (CASP-3) and malondialdehyde (MDA). Moreover, the impact on these parameters was greater in the combined exposure groups compared to the corresponding individual exposure groups. These findings suggested that both individual and combined exposures could induce mitochondrial dysfunction and lipid peroxidation damage, with combined exposure exacerbating the toxicological effects of each individual pollutant. Furthermore, at the molecular level, both individual and combined exposures upregulated the expression levels of cu-sod, cat, and erβ, while downregulating the expression of il-1. Similar to the patterns observed in the biochemical parameters, the combined exposure group exhibited a greater impact on the expression of these genes compared to the individual exposure groups. These results indicated that exposure to Cd, TRI, and their combination induced oxidative stress, endocrine disruption, and immunosuppression in fish livers, with more severe effects observed in the combined exposure group. Overall, the interaction between Cd and TRI appeared to be synergistic, shedding light on the toxic mechanisms by which fish livers responded to these pollutants. These findings contributed to the understanding of mixture risk assessment of pollutants and were valuable for the conservation of aquatic resources.

Nano-quercetin mitigates triazophos-induced testicular toxicity in rats by suppressing oxidative stress and apoptosis

The present study was designed to evaluate the testicular toxicity of triazophos in rats and to check the ameliorative effect of nano-quercetin against triazophos-induced toxicity. Nano-quercetin was synthesized from quercetin and characterized. Male Wistar rats were divided into seven groups. The control group received olive oil as a vehicle orally. The high-dose triazophos group and the low-dose triazophos group received 1/10th LD50 of triazophos (7.6 mg/kg) and 1/20th LD50 of triazophos (3.8 mg/kg), respectively. Two groups of animals were dosed with quercetin and nano-quercetin, both at 50 mg/kg body weight orally. The final two groups received high-dose triazophos with co-administration of quercetin and nano-quercetin, respectively. Triazophos disrupted the male endocrine axis by reducing the levels of steroidogenic enzymes 3-β-HSD and 17-β-HSD in testicular cells, further reducing FSH and testosterone. Also, triazophos increased the reactive oxygen species, induced lipid peroxidation, decreased the mitochondrial membrane potential, and elevated the number of apoptotic cells in rat testes. Nano-quercetin ameliorated the testicular oxidative stress and apoptotic and endocrine parameters more efficiently than quercetin. Besides, nano-quercetin alleviated the histopathological and biochemical alterations of triazophos. It is concluded that nano-quercetin has higher anti-oxidant efficacy than quercetin in protecting rats against triazophos-induced testicular toxicity.

Subacute exposure to Roundup® changes steroidogenesis and gene expression of the glutathione-glutaredoxin system in rat ovaries: Implications for ovarian toxicity of this glyphosate-based herbicide

Studies have indicated that glyphosate induces endocrine disruption and may adversely affect the male reproductive system. However, evidence of its effects on ovarian function is poorly understood so far, making further studies necessary on the mechanisms of the glyphosate toxicity in the female reproductive system. The aim of this work was to evaluate the effect of a subacute exposure (28 days) to the glyphosate-based formulation Roundup® (1.05, 10.5 and 105 μg/kg b.w. of glyphosate) on steroidogenesis, oxidative stress, systems involved in cell redox control and histopathological parameters in rat ovaries. Hence we quantify plasma estradiol and progesterone by chemiluminescence; non-protein thiol levels, TBARS, superoxide dismutase and catalase activity by spectrophotometry; gene expression of steroidogenic enzymes and redox systems by real-time PCR; and ovarian follicles by optical microscopy. Our results demonstrated that oral exposure increased progesterone levels and the mRNA expression of 3β-hydroxysteroid dehydrogenase. Histopathological analysis revealed a decrease in the number of primary follicles and an increase in the number of corpus luteum in rats exposed to Roundup®. An imbalance of the oxidative status was also evidenced by decreasing the catalase activity at all groups exposed to the herbicide. Increased lipid peroxidation and gene expression of glutarredoxin and decreased of glutathione reductase were also observed. Our results indicate that Roundup® causes endocrine disruption of hormones related to female fertility and reproduction and changes the oxidative status by altering antioxidant activity, inducing lipid peroxidation, as well as changing the gene expression of the glutathione-glutarredoxin system in rat ovaries.

Glyphosate effects on the female reproductive systems: a systematic review

Glyphosate-based herbicides (GBHs) are organophosphate pesticides, which interrupt the chemicals involved in the endocrine system and cause lifelong disorders in women's reproductive system. The current study was designed to systematically evaluate the association between GBH exposure and the female reproductive tract. According to PRISMA Guidelines, the systematic review was performed, searching online databases, including Google Scholar, Web of Science, PubMed, and Scopus, throughout April 2020. Studies with Rodent, lamb, and fish or exposed to GBH to affect the female reproductive system were selected. All studies were in the English language. Two investigators independently assessed the articles. The first author's name, publication date, animal model, age, sample size, gender, dose, duration, and route of exposure and outcomes were extracted from each publication. The present review summarizes 14 publications on uterus alterations and oocytes, histological changes ovary, and assessed mRNA expression, protein expression, serum levels progesterone, and estrogen and intracellular Reaction Oxygen Species (ROS) in rodents, fish, and lamb exposed to GHB exposure. Most of the studies reported histological changes in ovarian and uterus tissue, alterations in serum levels, and increased oxidative stress level following exposure to GBH. Additionally, due to alterations in the reproductive systems (e.g., histomorphological changes, reduction of the mature follicles, higher atretic follicles, and interstitial fibrosis), it seems the GBH-induced female these alterations are both dose- and time-dependent. The present findings support an association between GBH exposure and female reproductive system diseases. However, more studies are needed to identify the mechanisms disrupting the effects of GBH and their underlying mechanisms. Considering the current literature, it is recommended that further investigations be focused on the possible effects of various pesticides on the human reproductive system.

The role of oxidative stress in ovarian aging: a review

Ovarian aging refers to the process by which ovarian function declines until eventual failure. The pathogenesis of ovarian aging is complex and diverse; oxidative stress (OS) is considered to be a key factor. This review focuses on the fact that OS status accelerates the ovarian aging process by promoting apoptosis, inflammation, mitochondrial damage, telomere shortening and biomacromolecular damage. Current evidence suggests that aging, smoking, high-sugar diets, pressure, superovulation, chemotherapeutic agents and industrial pollutants can be factors that accelerate ovarian aging by exacerbating OS status. In addition, we review the role of nuclear factor E2-related factor 2 (Nrf2), Sirtuin (Sirt), mitogen-activated protein kinase (MAPK), protein kinase B (AKT), Forkhead box O (FoxO) and Klotho signaling pathways during the process of ovarian aging. We also explore the role of antioxidant therapies such as melatonin, vitamins, stem cell therapies, antioxidant monomers and Traditional Chinese Medicine (TCM), and investigate the roles of these supplements with respect to the reduction of OS and the improvement of ovarian function. This review provides a rationale for antioxidant therapy to improve ovarian aging.

Dietary naringin supplementation on laying performance and antioxidant capacity of Three-Yellow breeder hens during the late laying period

In this study, the effects of 3 graded dietary levels (0.1%, 0.2%, and 0.4%) of naringin were studied in Three-Yellow breeder hens during the late laying period (55-62 wk). A total of 480 Three-Yellow breeder hens (54-wk-old) were randomly divided into 4 groups (6 replicates of 20 hens): basal diet group (C), and basal diets supplemented with 0.1%, 0.2%, and 0.4% of naringin (N1, N2, and N3), respectively. Results showed that dietary supplementation with 0.1%, 0.2%, and 0.4% of naringin for 8 wk increased the laying rate and egg mass, enhanced egg yolk color, and decreased the feed egg ratio (P < 0.05). Meanwhile, compared with hens in C group, there were more preovulatory follicles and higher ovarian index as well as an enhanced ovarian somatic cell proliferation in hens of N2 and N3 groups (P < 0.05). With 0.2% and 0.4% naringin, glutathione concentration, the activity of catalase and total superoxide dismutase, and the total antioxidant capacity of ovarian tissues and serum increased (P < 0.05), while the contents of malondialdehyde and hydrogen peroxide decreased (P < 0.05). Moreover, compared to C group, the transcription levels of antioxidant genes in ovarian tissues increased in hens from N2 and N3 groups (P < 0.05). In conclusion, supplementation with 0.2% and 0.4% naringin both could improve the laying rate, ovarian and serum antioxidant capacity of Three-Yellow breeder hens during the late laying period.

The protective effects of thymol and carvacrol against di (2-ethylhexyl) phthalate-induced cytotoxicity in HEK-293 cells

The protective effects of thymol and carvacrol, two phenolic monoterpenes with a wide spectrum of pharmacological effects, against the oxidative stress produced by the di (2-ethylhexyl) phthalate (DEHP) in human embryonic kidney cells 293 cells (HEK-293 cells) were investigated in this study. The cytotoxicity was monitored by cell viability, while oxidative stress generation was assessed by reactive oxygen species (ROS) quantification, antioxidant enzyme activities measurement, glutathione concentration, and malondialdehyde (MDA) quantification. The genotoxicity was evaluated by the measurement of DNA fragmentation through the Comet assay. Our results demonstrated that the pretreatment of HEK-293 cells with thymol or carvacrol, 2 h before DEHP exposure, significantly increased the cell viability, decreased the ROS overproduction, modulated catalase (CAT), and superoxide dismutase (SOD) activities, restored the reduced glutathione content, and reduced the MDA level. The DNA fragmentation was also decreased by thymol and carvacrol pretreatment. These findings suggest that thymol and carvacrol could protect HEK-293 cells from DEHP-induced oxidative stress.

Pesticides: formulants, distribution pathways and effects on human health - a review

Pesticides are commonly used in agriculture to enhance crop production and control pests. Therefore, pesticide residues can persist in the environment and agricultural crops. Although modern formulations are relatively safe to non-target species, numerous theoretical and experimental data demonstrate that pesticide residues can produce long-term negative effects on the health of humans and animals and stability of ecosystems. Of particular interest are molecular mechanisms that mediate the start of a cascade of adverse effects. This is a review of the latest literature data on the effects and consequences of contamination of agricultural crops by pesticide residues. In addition, we address the issue of implicit risks associated with pesticide formulations. The effects of pesticides are considered in the context of the Adverse Outcome Pathway concept.

Novel metabolites of triazophos formed during degradation by bacterial strains Pseudomonas kilonensis MB490, Pseudomonas kilonensis MB498 and pseudomonas sp. MB504 isolated from cotton fields

In the current scenario of overuse of pesticides (resulting in soil and water pollution and ultimately leading to biomagnification), a research project was carried out to study biodegradation of Triazophos. For this purpose, three bacterial strains (Pseudomonas kilonensis MB490, Pseudomonas kilonensis MB498 and Pseudomonas sp. MB504), isolated from cotton fields of Mianwali, Pakistan were investigated for Triazophos degradation and metabolite formation in M-9 broth, soil slurry and soil microcosm after incubation for 9 days. There was 88.4-95.8% Triazophos degradation in M-9 broth, 99.90% degradation in soil slurry and 92.74 to 96% Triazophos degradation in soil microcosm by these bacteria after 9 days. While there was negligible Triazophos degradation (upto 7%) in the controls without bacteria. According to GCMS analysis, 7 unique and novel metabolites (1, 2, 4-Triazole-4-amine, N-(2-Thienylmethyl), Benzene sulfonic acid hydrazide, Benzene sulfonic acid methyl ester, 4H-1,2,4-Triazole-4-benzenesulfonamide, 4, 5 dihydro-N-(O-toyl)-3-furamide, Ethyl 4-phenyldiazenylbenzoate and Dibutyl methanephosphonate) of Triazophos were revealed. Current results strongly suggest the potential of these bacterial strains for the remediation of Triazophos contaminated agricultural soils.

Exposure to Organophosphate Pesticides and Menstrual Cycle Characteristics in Chinese Preconceptional Women

Organophosphates (OPs) are the most heavily used pesticides in China. The Chinese population, including preconceptional women, is highly exposed, yet little is known regarding the associations between OP exposure and menstruation in humans. We conducted a cross-sectional analysis in women preparing for pregnancy to investigate the relationship between biomarkers of OP exposure and menstrual cycle characteristics. From 2013 to 2015, 627 women visiting free preconception-care clinics at 2 maternity hospitals in Shanghai, China, were included. Information on menstrual cycle characteristics was obtained through questionnaires. OP exposure was assessed by measuring urine concentrations of 6 dialkylphosphate metabolites (dimethylphosphate, dimethylthiophosphate, dimethyldithiophosphate, diethylphosphate, diethylthiophosphate, and diethyldithiophosphate). The relationship between concentrations of dialkylphosphate metabolites and menstrual cycle characteristics was analyzed using multiple linear regression models and logistic regression models. Log-transformed levels of diethyl phosphate metabolites (the sum of diethylphosphate and diethylthiophosphate levels) were related to a higher risk of irregularity of menstrual cycles (adjusted odds ratio = 2.36, 95% confidence interval: 1.28, 4.34). Subjects with a higher concentration of diethyl phosphate metabolites (log-transformed) had a shorter duration of menstrual bleeding (adjusted β = -0.33, 95% confidence interval: -0.64, -0.02). The findings suggest that OP exposure may be associated with alterations in menstrual function in preconceptional women.

Assessment of the endocrine-disrupting effects of diethyl phosphate, a nonspecific metabolite of organophosphorus pesticides, by in vivo and in silico approaches

Organophosphorus pesticides (OPs) remain one of the most commonly used pesticides, and their detection rates and residues in agricultural products, foods and environmental samples have been underestimated. Humans and environmental organisms are at high risk of exposure to OPs. Most OPs can be degraded and metabolized into dialkyl phosphates (DAPs) in organisms and the environment, and can be present in urine as biomarkers for exposure to OPs, of which diethyl phosphate (DEP) is a high-exposure metabolite. Epidemiological and cohort studies have found that DAPs are associated with endocrine hormone disorders, especially sex hormone disorders and thyroid hormone disorders, but there has been no direct causal evidence to support these findings. Our study explored the effects of chronic exposure to DEP on endocrine hormones and related metabolic indicators in adult male rats at actual doses that can be reached in the human body. The results showed that chronic exposure to DEP could cause thyroid-related hormone disorders in the serum of rats, causing symptoms of hyperthyroidism in rats, and could also lead to abnormal expression of thyroid hormone-related genes in the rat liver. However, DEP exposure did not seem to affect serum sex hormone levels, spermatogenesis or sperm quality in rats. The molecular interactions between DEP and thyroid hormone-related enzymes/proteins were investigated by molecular docking and molecular dynamics methods in silico. It was found that DEP could strongly interact with thyroid hormone biosynthesis, blood transport, receptor binding and metabolism-related enzymes/proteins, interfering with the production and signal regulation of thyroid hormones. In vivo and in silico experiments showed that DEP might be a potential thyroid hormone-disrupting chemical, and therefore, we need to be more cautious and rigorous regarding organophosphorus chemical exposure.

Organophosphorus pesticide triazophos: A new endocrine disruptor chemical of hypothalamus-pituitary-adrenal axis

The organophosphorus pesticide, triazophos (TAP) was banned to use in agriculture in several countries due to its high toxicity. However, TAP was still widely used and frequently detected in foods. Recently, many studies reported the endocrine-disrupting effect of pesticides, especially the hypothalamic-pituitary-thyroid and hypothalamic-pituitary-gonadal axis. In this study, adult male Wistar rats were exposed to TAP at the dose of 0.164 and 1.64 mg/kg bodyweight (~1/500th and 1/50th of LD₅₀) for 24 weeks and serum contents of hormones were measured. TAP exposure significantly reduced serum contents of adrenocorticotropic hormone, corticosterone and epinephrine in rats (p < .05), leading to the delay in glucose homeostasis during the insulin tolerance test and decrease in serum contents of total cholesterol, triglyceride and low density lipoprotein. Molecular docking results suggested TAP may be an antagonist of glucocorticoid receptor which decreased significantly in the liver of rats, resulting in the decreased expression of 11β-hydroxysteroid dehydrogenase 1 and PEPCK1. This study revealed that TAP is a potential endocrine disruptor, especially in the hypothalamus-pituitary-adrenal system and may disturb the metabolism by affecting glucocorticoid receptor. This study provided new evidence about the toxicity of TAP and it was necessary to strictly control the usage of TAP in food.

Assessment of the endocrine-disrupting effects of organophosphorus pesticide triazophos and its metabolites on endocrine hormones biosynthesis, transport and receptor binding in silico

Triazophos (TAP) was a widely used organophosphorus insecticide in developing countries. TAP could produce specific metabolites triazophos-oxon (TAPO) and 1-phenyl-3-hydroxy-1,2,4-triazole (PHT) and non-specific metabolites diethylthiophosphate (DETP) and diethylphosphate (DEP). The objective of this study involved computational approaches to discover potential mechanisms of molecular interaction of TAP and its major metabolites with endocrine hormone-related proteins using molecular docking in silico. We found that TAP, TAPO and DEP showed high binding affinity with more proteins and enzymes than PHT and DETP. TAP might interfere with the endocrine function of the adrenal gland, and TAP might also bind strongly with glucocorticoid receptors and thyroid hormone receptors. TAPO might disrupt the normal binding of androgen receptor, estrogen receptor, progesterone receptor and adrenergic receptor to their natural hormone ligands. DEP might affect biosynthesis of steroid hormones and thyroid hormones. Meanwhile, DEP might disrupt the binding and transport of thyroid hormones in the blood and the normal binding of thyroid hormones to their receptors. These results suggested that TAP and DEP might have endocrine disrupting activities and were potential endocrine disrupting chemicals. Our results provided further reference for the comprehensive evaluation of toxicity of organophosphorus chemicals and their metabolites.

Effects of Diethyl Phosphate, a Non-Specific Metabolite of Organophosphorus Pesticides, on Serum Lipid, Hormones, Inflammation, and Gut Microbiota

Organophosphorus pesticides (OPs) can be metabolized to diethyl phosphate (DEP) in the gut environment, which may affect the immune and endocrine systems and the microbiota. Correlations between OPs and diseases have been established by epidemiological studies, mainly based on the contents of their metabolites, including DEP, in the serum or urine. However, the effects of DEP require further study. Therefore, in this study, adult male rats were exposed to 0.08 or 0.13 mg/kg DEP for 20 weeks. Serum levels of hormones, lipids, and inflammatory cytokines as well as gut microbiota were measured. DEP significantly enriched opportunistic pathogens, including Paraprevotella, Parabacteroides, Alloprevotella, and Helicobacter, leading to a decrease in interleukin-6 (IL-6). Exposure to the high dose of DEP enriched the butyrate-producing genera, Alloprevotella and Intestinimonas, leading to an increase in estradiol and a resulting decrease in total triglycerides (TGs) and low-density lipoprotein cholesterol (LDL-C); meanwhile, DEP-induced increases in peptide tyrosine‒tyrosine (PYY) and ghrelin were attributed to the enrichment of short-chain fatty acid-producing Clostridium sensu stricto 1 and Lactobacillus. These findings indicate that measuring the effects of DEP is not a proxy for measuring the effects of its parent compounds.

Triazophos-induced toxicity in zebrafish: miRNA-217 inhibits nup43

Triazophos is a highly toxic organophosphorus pesticide, causing acute toxicity to brain tissue, and neurotoxicity and embryotoxicity to animals. Therefore, triazophos is considered as a public health problem due to its acute hazard index. MicroRNAs (miRNAs), a class of endogenous noncoding RNAs, can regulate the expression of target gene(s) by mediating mRNA cleavage or translational repression in organisms exposed to environmental chemicals. We found that nup43 is targeted by miR-217, which was significantly regulated in adult zebrafish (Danio rerio) exposed to triazophos (phenyl-1,2,4-triazolyl-3-(o,o-diethyl thionophosphate)). The expression of nup43 in both mRNA and protein levels was downregulated in a dose-dependent manner upon stimulation with triazophos. A dual luciferase reporter assay demonstrated that miR-217 interacted with the 3'-untranslated regions (3'-UTR) of nup43. The expression of nup43 in both mRNA and protein level was reduced in ZF4 cells when transfected with an miR-217 mimic, but increased when transfected with an miR-217 inhibitor. As a result, nup43 is targeted by miR-217 upon triazophos exposure. We suggest that miR-217 could be a potential toxicological biomarker for triazophos.

A non-competitive surface plasmon resonance immunosensor for rapid detection of triazophos residue in environmental and agricultural samples

The wide application of an organophosphate pesticide triazophos raises concern on the environmental pollution and the potential risk to human health. Thus, it is crucial to regularly monitor triazophos residue in the environment and agro-products. Herein we described a non-competitive immunoassay for trace detection of triazophos using a direct surface plasmon resonance (SPR) biosensor. Two anti-triazophos monoclonal antibodies (mAbs) were immobilized on the sensor chip and characterized by SPR-based kinetic analysis. The mAb with relatively slow dissociation rate was used for direct immunosensing of triazophos. The biosensor assay showed a high specificity and a low detection limit of 0.096ngmL^-1 to triazophos, with the linear detection range of 0.98-8.29ngmL^-1. Under the optimal condition, the sensor chip could be regenerated for 160cycles at least. Moreover, the sensitive method was applied to determine triazophos in the spiked environmental water and agricultural products, as well as in unknown real-life samples (including Chinese cabbage, cucumber, and apple). Desirable results demonstrated that the newly-developed immunosensor could be used as a rapid, convenient, and reliable tool to regularly monitor triazophos and meet the detection requirement of its maximum residue limits.

Synergistic Effects of Heavy Metals and Pesticides in Living Systems

There is a widespread repeated exposure of the population to the pesticides and heavy metals of occupational and environmental origin. Such population is forced to undergo continuous stress imposed by combined exposure of the heavy metals and different classes of the pesticides used in agricultural as well as health practices. The existing reports from several workers have indicated that heavy metals and pesticides in combination may lead more severe impact on the human health when compared to their individual effects. Such a combination of pesticides and heavy metals may also change or influence the detection of exposure. Several studies in past have shown the synergistic toxic effects of heavy metals and pesticides. Such evaluations have revealed the synergistic interactions of various heavy metals and pesticides in animals as well as humans. The aim of the present article is to provide a synthesis of existing knowledge on the synergistic effects of heavy metal and pesticides in living systems. The information included in this article may be useful for different environment protection agencies and policy makers to consider the combined effects of heavy metals and pesticides on humans while designing strategies toward environmental protection and safety regulations about human health.

Expression and Functional Properties of an Anti-Triazophos High-Affinity Single-Chain Variable Fragment Antibody with Specific Lambda Light Chain

Triazophos is a widely used organophosphorous insecticide that has potentially adverse effects to organisms. In the present study, a high-affinity single-chain variable fragment (scFv) antibody with specific lambda light chain was developed for residue monitoring. First, the specific variable regions were correctly amplified from a hybridoma cell line 8C10 that secreted monoclonal antibody (mAb) against triazophos. The regions were then assembled as scFv via splicing by overlap extension polymerase chain reaction. Subsequently, the recombinant anti-triazophos scFv-8C10 was successfully expressed in Escherichia coli strain HB2151 in soluble form, purified through immobilized metal ion affinity chromatography, and verified via Western blot and peptide mass fingerprinting analyses. Afterward, an indirect competitive enzyme-linked immunosorbent assay was established based on the purified anti-triazophos scFv-8C10 antibody. The assay exhibited properties similar to those based on the parent mAb, with a high sensitivity (IC50 of 1.73 ng/mL) to triazophos and no cross reaction for other organophosphorus pesticides; it was reliable in detecting triazophos residues in spiked water samples. Moreover, kinetic measurement using a surface plasmon resonance biosensor indicated that the purified scFv-8C10 antibody had a high affinity of 1.8 × 10(-10) M and exhibited good binding stability. Results indicated that the recombinant high-affinity scFv-8C10 antibody was an effective detection material that would be promising for monitoring triazophos residues in environment samples.

Oxidative stress induced by chlorine dioxide as an insecticidal factor to the Indian meal moth, Plodia interpunctella

A novel fumigant, chlorine dioxide (ClO2) is a commercial bleaching and disinfection agent. Recent study indicates its insecticidal activity. However, its mode of action to kill insects is yet to be understood. This study set up a hypothesis that an oxidative stress induced by ClO2 is a main factor to kill insects. The Indian meal moth, Plodia interpunctella, is a lepidopteran insect pest infesting various stored grains. Larvae of P. interpunctella were highly susceptible to ClO2 gas, which exhibited an acute toxicity. Physiological damages by ClO2 were observed in hemocytes. At high doses, the larvae of P. interpunctella suffered significant reduction of total hemocytes. At low doses, ClO2 impaired hemocyte behaviors. The cytotoxicity of ClO2 was further analyzed using two insect cell lines, where Sf9 cells were more susceptible to ClO2 than High Five cells. The cells treated with ClO2 produced reactive oxygen species (ROS). The produced ROS amounts increased with an increase of the treated ClO2 amount. However, the addition of an antioxidant, vitamin E, significantly attenuated the cytotoxicity of ClO2 in a dose-dependent manner. To support the oxidative stress induced by ClO2, two antioxidant genes (superoxide dismutase (SOD) and thioredoxin-peroxidase (Tpx)) were identified from P. interpunctella EST library using ortholog sequences of Bombyx mori. Both SOD and Tpx were expressed in larvae of P. interpunctella especially under oxidative stress induced by bacterial challenge. Exposure to ClO2 gas significantly induced the gene expression of both SOD and Tpx. RNA interference of SOD or Tpx using specific double stranded RNAs significantly enhanced the lethality of P. interpunctella to ClO2 gas treatment as well as to the bacterial challenge. These results suggest that ClO2 induces the production of insecticidal ROS, which results in a fatal oxidative stress in P. interpunctella.