High doses of GrassOut Max poses reproductive hazard by affecting male reproductive function and early embryogenesis in Swiss albino mice

Clethodim is a widely used and approved class II herbicide, with little information about its impact on the reproductive system. Herein, we investigated the male reproductive toxicity of clethodim using a mouse model. GrassOut Max (26% clethodim-equivalent) or 50 mg kg^-1 body weight analytical grade clethodim (≥90%) were given orally to male mice for 10 d in varying doses. All parameters were assessed at 35 d from the first day of treatment. Significant decrease in testicular weight, decreased germ cell population, elevated DNA damage in testicular cells and lower serum testosterone level was observed post clethodim-equivalent exposure. Epididymal spermatozoa were characterized with significant decrease in motility, elevated DNA damage, abnormal morphology, chromatin immaturity and, decreased acetylated-lysine of sperm proteins. In the testicular cells of clethodim-equivalent treated mice, the expression of Erβ and Gper was significantly higher. Proteomic analysis revealed lower metabolic activity, poor sperm-oocyte binding potential and defective mitochondrial electron transport in spermatozoa of clethodim-equivalent treated mice. Further, fertilizing ability of spermatozoa was compromised and resulted in defective preimplantation embryo development. Together, our data suggest that clethodim exposure risks male reproductive function and early embryogenesis in Swiss albino mice via endocrine disrupting function.

Haloxyfop-P-methyl induces developmental defects in zebrafish embryos through oxidative stress and anti-vasculogenesis

Haloxyfop-P-methyl, an aryloxyphenoxypropionate herbicide, is widely used to eliminate unwanted plants by inhibiting lipid synthesis and inducing oxidative stress. Since haloxyfop-P-methyl targets are limited within plants, few negative side effects on non-target crops have been reported. However, dissolved haloxyfop-P-methyl in rain or groundwater contaminates aquatic environments and affects marine ecosystems. In the present study, treatment with haloxyfop-P-methyl for 48 h induced developmental deficiencies in the eyes and bodies of the zebrafish embryos as a whole and was also linked to increases in the incidence of pericardial edema. Additionally, haloxyfop-P-methyl treatment decreased hatching ratio, embryo viability, and heart rate, while simultaneously increasing the expression levels of apoptotic and inflammatory genes. Moreover, haloxyfop-P-methyl hampered vasculogenesis in the embryos through down-regulation of functional genes, and disruption of vessel formation caused neurodegeneration in the olig2-positive notochord. Collectively, this study newly discovered the oxidative stress-related toxic mechanism of haloxyfop-P-methyl during embryonic development through anti-vasculogenesis, which suppresses neurogenesis of the notochord. This toxicity assessment of haloxyfop-P-methyl on embryogenesis may contribute to establishment of safety profiling of herbicide and to support hazard control in aquatic environment.

Exposure to Spectracide® causes behavioral deficits in Drosophila melanogaster: Insights from locomotor analysis and molecular modeling

This study was focused on gaining insights into the mechanism by which the herbicide- Spectracide®, induces oxidative stress and alters behavior in Drosophila melanogaster. Exposure to Spectracide® (50%) significantly (p < 0.05) reduced the negative geotaxis response, jumping behavior and dampened locomotor activity rhythm in adult flies compared to non-exposed flies. Protein carbonyl levels indicative of oxidative damage increased significantly coupled with down-regulation of Sniffer gene expression encoding carbonyl reductase (CR) and its activity in Spectracide®-exposed flies. In silico modeling analysis revealed that the active ingredients of Spectracide® (atrazine, diquat dibromide, fluazifop-p-butyl, and dicamba) have significant binding affinity to the active site of CR enzyme, with atrazine having comparatively greater affinity. Our results suggest a mechanism by which ingredients in Spectracide® induce oxidative damage by competitive binding to the active site of a protective enzyme and impair its ability to prevent damage to proteins thereby leading to deficits in locomotor behavior in Drosophila.

Mice exposure to haloxyfop-p-methyl ester at predicted environmentally relevant concentrations leads to anti-predatory response deficit

Although the efficiency of haloxyfop-p-methyl ester (HPME) as selective herbicide is acknowledged, its impact on non-target organisms is poorly known. It is not known whether the short exposure of mammals to low HPME concentrations (consistent with a realistic contamination scenario) poses risks to these animals. Thus, the aim of the current study is to evaluate the effects of HPME on the anti-predatory behavior of female Swiss mice exposed to it. The animals were divided in groups: non-exposed (control) and exposed (route: i.p., for 2 days) to different herbicide concentrations (2.7 × 10^-4 g/kg and 2.7 × 10^-2 g/kg of body weight), which were considered environmentally relevant predicted concentrations. The animals were subjected to the open field and elevated plus-maze tests; results showed that the HPME did not lead to anxiolytic or anxiety behavior, or to locomotive changes in the tested animals, fact that was confirmed through the Basso Mouse Scale for locomotion scores. On the other hand, animals exposed to the herbicide were incapable of recognizing the snake as potential predator. Animals in the control group, exposed to a real snake (Pantherophis guttatus) remained longer in the safety zone of the test device, presented lower frequency of self-grooming behaviors for a shorter period-of-time, besides showing longer freezing time, which was not observed in animals exposed to HPME. Therefore, our study indicates the ecotoxicological potential of the herbicide, since anti-predatory behavior disorders may affect preys' responses and population dynamics.

Herbicides diuron and fluazifop-p-butyl affect avoidance response and multixenobiotic resistance activity in earthworm Eisenia andrei

The usage of pesticides has been steadily increasing over the last decades, and among them herbicides are the most commonly used ones. Despite their main mode of action targeting plant organisms, they can also have adverse effects on non-target animal organisms. In soil ecosystems, earthworms play an important role due to their positive impacts on the soil functioning and they represent good model organisms in soil ecotoxicology. The aim of the present study was to assess the effects of two herbicides on several endpoints at different levels of biological organization in the earthworm Eisenia andrei. Diuron and fluazifop-p-butyl were selected for the investigation and their lethal concentrations were determined: LC₅₀ 48 h: 89.087 μg/cm² for diuron and 6.167 μg/cm² for fluazifop-p-butyl. Furthermore, measurements of enzymatic biomarkers (catalase (CAT), acetylcholinesterase (AChE), carboxylesterase (CES) and glutathione S-transferase (GST)), multixenobiotic resistance (MXR) activity and gene expression of antioxidative enzymes (only for fluazifop-p-butyl) were conducted. Enzymatic biomarker responses showed no significant differences compared to the control after the exposure to the investigated herbicides, whereas the MXR activity was significantly inhibited. The gene expression level of superoxide dismutase (sod) and glutathione S-transferase (gst) after fluazifop-p-butyl exposure showed a significant increase. Finally, avoidance behavior in soil was assessed and it was determined that both herbicides caused significant avoidance response. The obtained results show that both investigated herbicides significantly affect earthworms on different levels of biological organization. This emphasizes the importance of comprehensive ecotoxicological assessment of herbicide effects on non-target organisms at all organizational levels.

Environmental Chemicals and Aging

PURPOSE OF REVIEW

Innovations in agriculture and medicine as well as industrial and domestic technologies are essential for the growing and aging global population. These advances generally require the use of novel natural or synthetic chemical agents with the potential to affect human health. Here, we attempt to highlight environmental chemicals and select drugs with the potential to exacerbate aging by directly affecting molecular aging cascades focusing particular attention on the brain. Finally, we call attention to some potential fruitful areas of research, particularly with advanced molecular profiling that could aid in prevention or mitigation of environmental chemical toxic influences in the periphery and the brain.

RECENT FINDINGS

We briefly summarize new research and highlight a recent study designed to prospectively identify agrochemicals with the potential to induce neurological diseases and place these discoveries into the already rich neurodegeneration and aging literature. Collectively, the research reviewed briefly here highlight chemicals with the true potential to accelerate aging, particularly in the brain, by eliciting elevated free radical stress and mitochondrial dysfunction. We make general recommendations about improved methodological approaches toward identification and regulation of chemicals that are gerontogenic to the brain.

Impacts on the seagrass, Zostera nigricaulis, from the herbicide Fusilade Forte® used in the management of Spartina anglica infestations

The herbicide Fusilade Forte^® (FF) is widely applied in agricultural weed management and in the management of the invasive saltmarsh grass, Spartina anglica (ricegrass or cordgrass). FF (active ingredient fluazifop-P acid, FPA) is selective for poaceous grasses. Its primary mode of action is inhibition of the acetyl coenzyme-A carboxylase (ACCase) specific to this taxonomic group, and its secondary mode is by promotion of oxidative stress. FF is applied to S. anglica infestations in the intertidal zone, in proximity to seagrass meadows. Despite the potential for vital seagrass ecosystems to be exposed to FF, there is limited knowledge of any potential impacts. We investigated impacts of FPA on the endemic Australian seagrass, Zostera nigricaulis, measuring ACCase activity and parameters that reflect oxidative stress: photosynthetic performance, lipid peroxidation and photosynthetic pigment content. Seagrass was exposed to FF (0.01-10mgL^-1 FPA and a control) for 7d, followed by a 7-d recovery in uncontaminated seawater. An enzyme assay demonstrated that FPA ≤10mgL^-1 did not inhibit the activity of ACCase isolated from Z. nigricaulis, demonstrating that this seagrass is resistant to FF's primary mode of action. However, physiological impacts occurred following 7 days exposure to ≥0.1mgL^-1 FPA, including up to a 72% reduction in photosynthetic pigment concentration. After 7-d recovery, photosynthetic pigment content improved in treatment plants; however, treated plants exhibited higher levels of lipid peroxidation. This study demonstrates that while Z. nigricaulis is resistant to FF's primary mode of action, significant physiological impacts occur following 7 days exposure to ≥0.1mgL^-1 FPA. This study provides valuable information on the effects of FF on a non-target species that can better inform approaches to Spartina management in coastal seagrass ecosystems.

Hepatotoxicity, Nephrotoxicity and Oxidative Stress in Rat Testis Following Exposure to Haloxyfop-p-methyl Ester, an Aryloxyphenoxypropionate Herbicide

Haloxyfop-p-methyl ester (HPME) ((R)-2-{4-[3-chloro-5-(trifluoromethyl)-2-pyridyloxy]phenoxy}propionic acid), is a selective aryloxyphenoxypropionate (AOPP) herbicide. It exerts phytotoxicity through inhibition of lipid metabolism and induction of oxidative stress in susceptible plants. This study investigated the toxicological potentials of HPME in rats. Twenty-four male Wistar rats (170–210 g) were randomized into four groups (I–IV). Group I (control) received 1 mL of distilled water, while animals in Groups II, III and IV received 6.75, 13.5 and 27 mg/kg body weight HPME, respectively, for 21 days. There was a significant (p < 0.05) increase in renal and hepatic function biomarkers (urea, creatinine, total bilirubin, ALP, ALT, AST) in the plasma of treated animals compared to control. Levels of testicular antioxidants, ascorbic acid and glutathione, and activities of glutathione-S-transferase, superoxide dismutase and catalase were reduced significantly after 21 days of HPME administration in a dose-dependent manner. The testicular malondialdehyde level increased significantly in the HPME-treated rats relative to the control. A significant decrease in testicular lactate dehydrogenase, acid phosphatase and γ-glutamyl transferase was also observed in HPME-treated animals. Testicular histology revealed severe interstitial edema and sections of seminiferous tubules with necrotic and eroded germinal epithelium in the HPME-treated rats. Overall, data from this study suggest that HPME altered hepatic and renal function and induced oxidative stress and morphological changes in the testis of rats.