Concentrations Of Glyphosate Research Articles

Facile Fabrication of Amino-Functionalized Silicon Flakes for Removal of Organophosphorus Herbicide: In Silico Optimization

In the present study, a toxic herbicide (glyphosate) was remediated through adsorption using biogenic conversion of amino-functionalized silica nanoparticles (silica NPs). The glyphosate adsorption and silica NPs were characterized using kinetics, isotherm and thermodynamics models, pH zero point charge measurements, BET surface analysis, X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy/energy-dispersive X-ray spectroscopy and regeneration study. The adsorption data were optimized by ANN multi-layer perceptron and multiple linear regression. The equilibrium glyphosate adsorption data were fitted to Freundlich, Langmuir, Temkin and Dubinin-Radushkevich (D-R) isotherm models. The adsorption capacity values recorded for the Freundlich and Langmuir models were 233.34 L/mg and 212.76 mg/g, respectively, at the maximum saturation dose. The fast rate-determining kinetics data were described by a pseudo-second-order model at different concentrations. The thermodynamics parameters clearly revealed that the adsorption of glyphosate was endothermic and spontaneous in nature. Finally, the optimized conditions were recorded as follows: initial glyphosate concentration 39.99 mg/L, pH 12.66, dose 0.299 g, contact time 60 min, and temperature 100 °C, with 98.99% removal. More importantly, the silicon NPs were easily recovered in different media, with acetic acid medium showing excellent regeneration. The present findings suggest that silicon NPs are a promising adsorbent for glyphosate removal from aqueous solutions.

Palatability of glyphosate in ants: a field experiment reveals broad acceptance of highly polluted solutions in a Mediterranean ant.

Glyphosate is a systemic herbicide still used in many countries, though there are several known detrimental effects on animals. Previous studies concerning its effects on social insects are available, but they are primarily focused on honeybees; little is known about the interactions of this compound with ants. Here, we assessed whether different concentrations of glyphosate can be perceived by ant workers and to what extent. As a model species, we used the Mediterranean ant Crematogaster scutellaris, commonly found in agroecosystems. We performed 3000 individual tests of acceptance using ten different solutions of various concentrations of the herbicide. Half of the solutions contained added sucrose in order to test the possible masking effect of the sugar taste on glyphosate. We used comparable glyphosate concentrations to those previously used in other studies on social insects or suggested by the producer. We found that the acceptance of the solutions decreased as the concentration of the herbicide increased. However, a significant percentage of ants drank the solutions with concentrations up to dozens of times higher than those inducing toxic effects in bees. In light of these results, we urge further assessment of the effects of glyphosate on ants, particularly because the food ingested by workers is transferred to the brood and queens, posing a potential threat to the health of the entire colony. Surprisingly, we did not record any difference in acceptance between solutions with and without sugar; this point is discussed regarding drought stress.

Analysis of the presence of glyphosate in sediments from the hydrographic basin dam of the São João stream in the municipality of Porto Nacional, Tocantins

Agricultural production has been one of the activities that most affect the quality of fresh water, due to accelerated urbanization, as well as the growing agricultural production in the region such as corn and soy in order to meet the high consumption demanded by the population, such activities have influenced drastically hydrographic basin conditions due to the excessive use of pesticides. Among the consequences caused are soil erosion, silting, increased production of sediments as well as water turbidity. Through studies related to sediments, it was possible to notice that their structures retain most of the chemical products, through the processes of adsorption, infiltration, and sorption in the soil. This in fact resulted in a study to assess the quality of the São João stream hydrographic basin, which covers the city of Porto Nacional Tocantins, being the main source of surface supply. With the main objective of analyzing the manifestations of chemical products resulting from agricultural use through the collection of sediment samples from the São João stream dam to check the presence of glyphosate, in addition to soil particle size characterization, for particle size classification. From the results obtained in the laboratory, it was observed that the soil presented a high granulometric variation, which despite containing a small percentage of fines such as silt, most of the sample consists of medium sand, coarse sand and gravel responsible for 86.66 % of the total sample. The result obtained an average value of 0.02 μg / L. Then, the results were compared to the values specified by the environmental legislation, in its resolution 357/2005 of the National Environment Council. The values showed the manifestation of the herbicide present in the sample, contacting the vulnerability of water resources, as a result of the poor management of the hydrographic basin, in which the concentrations of agrochemical chemical glyphosate did not show results superior to those allowed by the CONAMA resolution 307/2005. However, due to the growing agricultural activity in the region, this must be periodically evaluated so that it does not reach alarming numbers, subsequently harming water quality.

A turn-on fluorescent nanoprobe based on N-doped silicon quantum dots for rapid determination of glyphosate.

N-Doped silicon quantum dots (N-SiQD) were synthesized using N-[3-(trimethoxysily)propyl]-ethylenediamine and citric acid as silicon source and reduction agent, respectively. The N-SiQD shows a strong blue fluorescence with a high quantum yield ofabout 53%. It is found that a selective static quenching process occurs between N-SiQDs and Cu2+. Glyphosate can inhibit this phenomenon and trigger the rapid fluorescence enhancement of the quenched N-SiQDs/Cu2+ system due to the specific interaction between Cu2+ and glyphosate. With such a design, a turn-on fluorescent nanoprobe based on N-SiQD/Cu2+ system was established for rapid determination of glyphosate. The determination signal of N-SiQD/Cu2+ was measured at the optimum emission wavelength of 460nm after excitation at 360nm. Under optimal conditions, the turn-on nanoprobe showed a linearrelationship between fluorescent response and glyphosate concentrations in therange 0.1 to 1μgmL-1. The limit of determination was calculated to 7.8ngmL-1 (3σ/S). Satisfactory recoveries were obtained inthe determination of spiked water samples, indicating the potential use forenvironmental monitoring. Graphical abstract Schematic representation of N-SiQD/Cu2+ system for glyphosate determination. Fluorescence quenching of N-SiQDs induced by copper ions and the succedent fluorescent "turn on" triggered by glyphosate.

Biodegradation capabilities of acclimated activated sludge towards glyphosate: Experimental study and kinetic modeling

The acclimation process of activated sludge from a wastewater treatment plant for degradation of glyphosate and its biodegradation kinetics were studied in a batch reactor. The parameters monitored included the concentrations of glyphosate, as well as aminomethylphosphonic acid (AMPA), its main metabolite, total organic carbon (TOC), pH, dissolved oxygen (DO) and biomass concentration. At the end of the acclimation process, glyphosate removal efficiency of the acclimated sludge was compared to the fresh sludge one. The results showed that the acclimation process highly increased degradation efficiency. Complete glyphosate removal has been achieved during kinetics experiments. Glyphosate removal kinetic of the acclimated sludge was modeled by Monod model that accurately fitted the experimental results with a maximum growth rate (μmax) of 0.34 h−1 and half-saturation constant (Ks) of 1600 mg L−1. Finally, a biodegradation pathway of glyphosate used as carbon source was proposed.

Nanostructured electrode using CMK-8/CuNPs platform for herbicide detection in environmental samples

A simple and sensitive nanostructured electrode was designed by electrodepositing copper nanoparticles (CuNPs) on a screen-printed carbon electrode (SPCE) modified with an ordered mesoporous carbon (CMK-8) in order to detect glyphosate (GLY) in river water samples. CMK-8 was immobilized onto an SPCE using chitosan polymer (CH) as a binder, followed by CuNPs electrodeposition. CuNPs/CMK-8-CH/SPCE was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, transmission electron microscopy, scanning electron microscopy, energy dispersive spectrometry, and N2 adsorption–desorption isotherms.CMK-8 has a high specific surface area, large pore volume, uniform mesostructure, good conductivity, and excellent electrochemical activity. This mesoporous carbon material provides the sensitivity for the indirectly electrochemical determination of GLY by square wave voltammetry. The anodic currents increased proportionally to the concentrations of GLY due to a complexation process. The detection limit achieved by the designed electrochemical device was 0.09 ng mL−1 with a linear range from 0.3 ng mL−1 to 19.75 ng mL−1 with intra and inter-assay coefficients of variation below 5%. This electrochemical platform represents an attractive strategy for on-site GLY determination in environmental samples.

Earthworms to improve glyphosate degradation in biobeds.

In this work, earthworm effect on the efficiency of biobeds for glyphosate degradation was studied. Three biomixtures with and without the addition of earthworms (Eisenia fetida species) were evaluated. The initial concentration of glyphosate was 1000mg/kg biomixture. Glyphosate and biological parameters were measured as a function of time. Earthworm survival, biomass, and reproduction were evaluated as well. All biomixtures that contain earthworms reached 90% of glyphosate degradation at 90days in comparison with the biomixtures without earthworms that reached 80% approximately at the same time. Also, within the biomixtures that contained earthworms, glyphosate degradation rate was significantly higher in the one made up with soil and wheat stubble (Ws-E) showing excellent capacity for aminomethylphosphonic acid (AMPA) degradation, the main metabolite of glyphosate degradation. In addition, a study performed after the vermiremediation process showed that E. fetida can tolerate high glyphosate concentration without modifications in its life traits. It can be concluded that the use of E. fetida within the biobeds is an excellent combination to improve glyphosate and AMPA removal.

Monocrystalline silicon/polyaniline/horseradish peroxidase enzyme electrode obtained by the electrodeposition method for the electrochemical detection of glyphosate

A silicon/polyaniline/horseradish peroxidase enzyme (n-Si/PANI/HRP) electrode was obtained by potentiostatic electrodeposition processes. PANI thin films were electropolymerized on a silicon substrate at different electric potentials, and an HRP enzyme was electrodeposited on the best PANI thin film. The best PANI thin film was obtained under electrodeposition conditions of + 1.00 V (vs. Ag/AgCl) and 900 s, and the immobilization of the HRP enzyme was performed at an electric potential of − 0.50 V (vs. Ag/AgCl). The n-Si/PANI- and n-Si/PANI/HRP electrodes were characterized using scanning electron microscopy and atomic force microscopy. The detection capacity of the glyphosate of the n-Si/PANI/HRP electrode with the best morphological characteristics was evaluated according to the electric current density responses from the oxidation of hydroquinone molecules in a solution containing different concentrations of glyphosate. The detection was performed because of the inhibition of the HRP enzyme activity by the glyphosate molecules in the solutions with a lower concentration limit of 5.44 μg L−1 over an electric potential range of + 0.65 to + 1.15 V (vs. Ag/AgCl).

A modified in-planta transformation technique to generate stable gain-in function transformants in a recalcitrant indica rice genotype

A tissue culture independent in-planta transformation technique is an alternate option to generate transgenics in crop cultivars recalcitrant for regeneration. The T0 plants generated by in-planta technique are chimeric hence very large number of T1 seeds needs to be screened to identify the putative transformants. Besides, low transformation efficiency and stable integration is another lacuna, because the T0 seedling explants are not subjected for selection. To overcome these constraints, a modified in-planta technique was developed in this study to generate gain-in-function activation tagged mutants in the background of a recalcitrant rice genotype, KMP-153. A binary vector was developed with three glyphosate selectable marker genes and 4X CaMV 35S enhancer elements for developing rice plants. Simultaneous expression of Glyphosate insensitive CP4-EPSPS with two other glyphosate degrading enzymes, PsAKR1 (Aldo–Keto reductases) and GO (Glycine Oxidase) substantially improved tolerance up to 100 ppm of glyphosate in the seedling bioassay system. Selecting the seedling explants and T1 generation seeds at higher concentration (100 ppm) of glyphosate resulted in recovering fewer transformants but with stable integration and expression of all the transgenes compared to those screened at lower levels of glyphosate. Further, T2 generation plants from these transgenic lines grown in contained nethouse conditions were tolerant when sprayed up to 1500 ppm concentrations of glyphosate. These transgenics showed substantial lower levels of shikimic acid compared to wild type plants treated with glyphosate signifies the expression of the transgenes and less inhibition of shikimic acid pathway by glyphosate. The proteins extracted from the transgenic plants showed significant degradation of glyphosate. The stable integration was confirmed through flanking sequence information and event specific PCR information. Our results clearly demonstrate that the modified in-planta technique is a potential transformation protocol to generate stable transformants in rice cultivars.

Can environmental concentrations of glyphosate affect survival and cause malformation in amphibians? Effects from a glyphosate-based herbicide on Physalaemus cuvieri and P. gracilis (Anura: Leptodactylidae).

Herbicides are the most common agrochemicals used in crops. Among them, glyphosate is the most widely applied in the world. Herbicides, especially organophosphates, have been shown to be hazardous to non-target species, including amphibians. The present study evaluated the acute and chronic effects of glyphosate-based herbicide (GBH), Roundup original® DI on tadpoles from two South American native species, Physalaemus cuvieri and P. gracilis. Spawnings were collected in the natural environment and maintained in the laboratory under controlled conditions. Acute and chronic toxicology trials began at stage 25 of Gosner (Herpetological 16:183-190, 1960). In an acute toxicity assay, seven GBH concentrations between 100 and 4500μg a.e./L were tested over 96h. For the chronic trials, tadpoles were subjected to both doses allowed by Brazilian legislation and to concentrations found in natural environment waters from Brazil and Argentina, between 65 and 1000μg a.e/L over 14days. Glyphosate had lethal effects on both studied species. Tadpoles showed shorter lengths and lower masses; that is, those that survived suffered chronic effects on growth and weight. The GBH maximum acceptable toxicant concentration for mortality and malformation was lower than the allowed level for Brazilian waters. The GBH tested in this study presented a high environmental and acute risk for the two studied species.

Effects of a glyphosate-based herbicide on the development and biochemical biomarkers of the freshwater copepod Notodiaptomus carteri (Lowndes, 1934).

In this work we analyzed the effects of Sulfosato Touchdown®, a glyphosate-based herbicide, on the ontogenic development and biochemical markers of the freshwater copepod Notodiaptomus carteri. A 30-days life-cycle experiment was carried out with three different glyphosate concentrations (0, 0.38, and 0.81mgL-1) to analyze the developmental time from nauplii to adult copepods and their individual growth. An additional 10-days experiment with the same glyphosate concentrations was designed to evaluate the energy reserves (glycogen, proteins and lipids) and the activity of three antioxidant enzymes, superoxide dismutase (SOD), catalase, and glutathione-S-transferase (GST) in adult copepods, separately for females and males. We found that the lowest glyphosate concentration increased the nauplii and total development time. The highest glyphosate concentration prevented copepods from reaching the adult stage, inhibited the growth of the first copepodite stage and increased the GST and SOD activity in adult females. According to our results, the presence of this herbicide in freshwater systems could impose a risk in the ecological role of copepods in nature. This study will contribute to propose the Notodiaptomus genus as model specie for monitoring purposes in the Neotropical aquatic systems.

Concentration Distribution and Analysis of Urinary Glyphosate and Its Metabolites in Occupationally Exposed Workers in Eastern China.

Background: There are few published studies concerning occupational exposure to glyphosate (GLY), and these are limited to spraying, horticulture and other agricultural aspects. Therefore, the concentration of glyphosate and its metabolite aminomethylphosphonic acid (AMPA), in the urine of workers exposed to glyphosate during glyphosate production was determined, and the relationship between internal (urinary glyphosate and AMPA concentration) and external exposure dose (time weighted average (TWA) value of glyphosate in the air of workplace) was analyzed. Methods: To avoid the influence of preparations, we selected people who were only involved in GLY production (without exposure to its preparations) as our research subjects. We collected 134 urine samples of workers exposed to GLY (prototype, not preparation). The urinary concentrations of GLY and AMPA (internal exposure dose) were detected by gas chromatography-mass spectrometry. The subjects’ exposure to the amount of GLY in the air (external dose) was determined using ion chromatography. Conventional statistical methods, including quartiles, t-tests and regression analysis, were applied for data processing. Results: An on-site investigation revealed that the workers involved in centrifugation, crystallization, drying, and packaging and feeding were exposed to GLY. The TWA value of GLY in the workshop air was <0.02 mg/m3–34.58 mg/m3. The detection rates of GLY and AMPA in the urine samples were 86.6% and 81.3%, respectively. The concentration of urinary GLY was <0.020–17.202 mg/L (median, 0.292 mg/L). The urinary AMPA concentration was <0.010 mg/L–2.730 mg/L (median, 0.068 mg/L). The geometric means were 0.262 mg/L and 0.072 mg/L for GLY and AMPA, respectively. There was a correlation between the urinary concentration of GLY and AMPA and the TWA value of exposed workers (correlation coefficient [r] = 0.914 and 0.683, respectively; p < 0.01). Furthermore, there was a correlation between the urinary concentration of GLY and AMPA in the exposure group (r = 0.736, p < 0.01). Conclusions: The urinary concentration of GLY and AMPA of workers was correlated with the TWA value of workers’ exposure, which could reflect the actual exposure of the workers.

Effects of Glyphosate on Locomotion and Anxiety‐like Behavior in Rats

Glyphosate is the active ingredient in several commercial herbicides. The development of glyphosate‐resistant seeds has led to an increase in the use of glyphosate in agriculture. This has resulted in the exposure of non‐agricultural lands and bodies of water to glyphosate. Though initially considered safe for mammals, recent studies in rats have shown that administration of glyphosate leads to alterations in locomotion and anxiety‐like behavior. These studies generally used unrealistically high concentrations of glyphosate. Therefore, the effects of a dose of glyphosate considered safe by the Environmental Protection Agency through drinking water remain unclear. To determine if these levels affect locomotion and anxiety‐like behavior, we provided rats with access ad libitum to glyphosate‐contaminated drinking water or filtered water for four weeks. Glyphosate‐contaminated water was prepared for a target dose of 1.75mg/kg of glyphosate daily. We hypothesize that intake of glyphosate‐contaminated drinking water will decrease locomotion and increase anxiety‐like behavior. Locomotion was assessed in an open field. We observed that glyphosate did not decrease the overall distance travelled (control: 30.67m, glyphosate: 23.70m; p=0.058) nor did it affect average speed (control: 0.102m/s, glyphosate: 0.079; p=0.058). Anxiety‐like behaviors were also measured in the open field. Here, glyphosate did not increase the amount of entries to the center (control: 25.5, glyphosate: 27.5; p=0.726) nor time spent in the center (control: 74.22s, glyphosate: 87.9; p=0.572). In conclusion, this dose and exposure time of glyphosate did not affect locomotion or anxiety‐like behavior. Future directions include performing immunohistochemistry to assess neuronal activity in brain regions involved in locomotion and anxiety‐like behaviors.Support or Funding InformationYoung Investigator grant (NARSAD) of the Brain &amp; Behavior Research Foundation, PRCTRC Pilot, NIGMS COBRE and RCMI8G12MD00760 to DS‐M; NSF PRCEN fellowships to CJR‐S, MC‐C, HH‐M, RR‐S and MR‐L, UPR Med Sci Campus Chancellor’s Office and School of Medicine Deanship.

Behavioural toxicity of environmental relevant concentrations of a glyphosate commercial formulation - RoundUp® UltraMax - During zebrafish embryogenesis

The use of herbicides with glyphosate as an active ingredient (a.i.) has increased dramatically in recent years, with its residues often being found in either soil or water. Nevertheless, concerns have arisen about its harmful side effects for both ecosystems and wildlife health. Therefore, the objective of this work was to assess the effects of a commercial formulation of glyphosate (RoundUp® UltraMax), at environmentally relevant concentrations on zebrafish embryos through a set of behavioural patterns. Zebrafish embryos were exposed to 0, 1, 2 and 5 μg a.i. mL−1 concentrations of the glyphosate formulation for 72 h (from 2.5 to 75 h post-fertilization (hpf)). After exposure, larvae were washed and allowed to develop until 144 hpf. At this point, the larvae behaviour was evaluated using a battery of tests to assess the general exploratory motility, escape-like responses, anxiety-related behaviours and social interactions. In addition, cortisol levels were assessed. No significant changes were observed relative to the exploratory behaviour in the standard open field. The anxiety-related behaviours were similar among groups, and no social interference was observed following exposure to these glyphosate concentrations. Likewise, cortisol levels remained similar among treatments. Still, the larvae exposed to 5 μg a.i. mL−1 did not react to the presence of an aversive stimulus, supporting glyphosate-induced changes in the sensory-motor coordination during development. In general, these results indicate a possible neurotoxic effect of this glyphosate-based formulation that should be further evaluated. In addition, the results obtained could impose a risk for wildlife sensitive species that should not be neglected.

Glyphosate and AMPA levels in human urine samples and their correlation with food consumption: results of the cross-sectional KarMeN study in Germany

Glyphosate (N-[phosphonomethyl]-glycine) is the most widely used herbicide worldwide. Due to health concerns about glyphosate exposure, its continued use is controversially discussed. Biomonitoring is an important tool in safety evaluation and this study aimed to determine exposure to glyphosate and its metabolite AMPA, in association with food consumption data, in participants of the cross-sectional KarMeN study (Germany). Glyphosate and AMPA levels were measured in 24-h urine samples from study participants (n = 301). For safety evaluation, the intake of glyphosate and AMPA was calculated based on urinary concentrations and checked against the EU acceptable daily intake (ADI) value for glyphosate. Urinary excretion of glyphosate and/or AMPA was correlated with food consumption data. 8.3% of the participants (n = 25) exhibited quantifiable concentrations (> 0.2 µg/L) of glyphosate and/or AMPA in their urine. In 66.5% of the samples, neither glyphosate (< 0.05 µg/L) nor AMPA (< 0.09 µg/L) was detected. The remaining subjects (n = 76) showed traces of glyphosate and/or AMPA. The calculated glyphosate and/or AMPA intake was far below the ADI of glyphosate. Significant, positive associations between urinary glyphosate excretion and consumption of pulses, or urinary AMPA excretion and mushroom intake were observed. Despite the widespread use of glyphosate, the exposure of the KarMeN population to glyphosate and AMPA was found to be very low. Based on the current risk assessment of glyphosate by EFSA, such exposure levels are not expected to pose any risk to human health. The detected associations with consuming certain foods are in line with reports on glyphosate and AMPA residues in food.

Glyphosate and AMPA concentrations in the respirable dust emitted experimentally by soil aggregates, shortly after herbicide application

The objective of this study was to analyze glyphosate- and aminomethylphosphonic acid (AMPA) concentrations in the respirable dust (RD) emitted by different soil aggregates, shortly after herbicide application in a field approach. The relationships of both glyphosate and AMPA in the aggregates with organic matter- (OM), total iron- (Fe), and extractable phosphorus contents (P) as well as with pHCaCl2 values were analyzed. An Kastanozem haplic of the Semiarid Pampas (Argentina) was analyzed 7 days after glyphosate application. The RD (particulate matter <10 mm in diameter, PM10) was generated and collected for the following aggregate-size fractions: <0.42 mm, 0.42 to 0.84 mm, 0.84 to 2 mm, 2 to 6.4 mm, 6.4 to 19.2 mm, and >19.2 mm. OM, P, Fe and pHCaCl2 were analyzed in the aggregate fractions, and glyphosate- and AMPA contents were measured both in RD and in the aggregate fractions. Glyphosate concentration varied between 16 mg kg−1 (aggregates <0.42 mm) and 4.7 mg kg−1 (aggregates >19.2 mm) and increased with decreasing size of the aggregates. Glyphosate concentration in RD varied between 48.5 mg kg−1 (aggregates <0.42 mm) and 17.8 mg kg−1 (aggregates >19.2 mm). Finest aggregates emitted RD with higher glyphosate concentrations. A positive relationship was determined between glyphosate in aggregates and glyphosate in RD (p < 0.05), indicating that aggregates with higher glyphosate concentration emitted a more glyphosate-enriched RD. Glyphosate in the aggregate fractions was not related to Fe, OM or pH of aggregates. Glyphosate- and P concentrations in aggregates were positively correlated. This is explained because both substances share a phosphonic acid functional group and they have similar reactivities in the soil. AMPA concentration varied between 130 mg kg−1 (aggregates >19.2 mm) and 307 mg kg−1 (aggregates <0.42 mm) in aggregates and between 527 ug kg−1 and 746 ug kg−1 in RD. AMPA concentrations in RD were not related to AMPA concentrations in aggregates. The contents of AMPA were higher than those of glyphosate in both, RD and aggregates, due to the longer persistence of AMPA in relation to glyphosate. In all cases, glyphosate- and AMPA concentrations were higher in RD than in the aggregates. Our results suggest that the RD emitted by agricultural soils has higher glyphosate- and AMPA concentrations than the bulk soil. These results encourage future investigations to elucidate if other pesticides (and the surfactants used in their formulations) are present in the RD emitted by agricultural soils. This information is necessary in order to evaluate the effects of the particulate matter emitted by agricultural soils on the whole ecosystem and the human health.

Pesticide-induced alteration in proteins of characterized soil microbiota revealed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE)

Beneficial soil bacteria including Pseudomonas fluorescens, Burkholderia, cepacia, Azotobacter vinelandii, Rhizobium leguminosarum and Bradyrhizobium japonicum identified by 16S rRNA gene sequence analysis tolerated maximum concentrations of glyphosate (herbicide) and kitazin (fungicide). Pesticides declined the phytohormone-synthesizing ability of PGPR strains. As an example, the higher (3X) level of kitazin reduced maximally IAA synthesizing ability of PGPR strains PS3, PSBB1, AZ2, RP1 and RV9 by 51, 28, 82, 35 and 59%, respectively, than control. Impact of different concentrations of glyphosate and kitazin on bacterial proteins differed considerably (p < 0.05). For instance, total protein content each of PS3 (111.3 μg mL−1), PSBB1 (80.2 μg mL−1), AZ2 (76.3 μg mL−1), RP1 (94.2 μg mL−1) and RV9 (62 μg mL−1) was maximally decreased by 34, 45, 85, 34 and 80%, respectively, at 3X doses of kitazin. Also, total whole-cell bacterial proteins revealed by SDS-PAGE declined in a concentration-dependent manner. As glyphosate and kitazin concentrations increased, protein bands were either decreased/disappeared or induced the formation of some new bands. For example, 400, 800 and 1200 μgmL−1 of kitazin-treated extract of P. fluorescens PS3 showed some new bands of around 200, 125, 90 and 70 kDa, whereas protein bands of 250, 150, 100, 75 and 50 kDa were vanished/disappeared. This study indicates that both glyphosate and kitazin are inhibitory to phytohormone production and bacterial protein synthesis mechanism and hence, provides baseline data that warrant use of pesticides in soil/rhizosphere where such bacterial communities are used as microbial inoculants.

Interaction between glyphosate and dissolved phosphorus on bacterial and eukaryotic communities from river biofilms

Since the capacity of river biofilms to degrade glyphosate has been proven to increase when the availability of dissolved phosphorus (P) in water decreases, the present study investigates the diversity responses of bacterial and eukaryotic microbial communities from biofilms in a search for glyphosate-degrader candidates. Glyphosate and P interactions were observed for eukaryotic communities, the highest community richness and diversity being preserved at low concentrations of glyphosate and P. This trend marked by glyphosate was also observed in the structure of eukaryotic communities. Therefore, phosphorus and glyphosate had a synergistic effect in decreasing the richness and diversity of eukaryotes species in biofilms. However, species richness and diversity in bacterial communities were not affected by glyphosate, though shifts in the structure of these communities were concomitant with the degradation of the herbicide. Bacterial communities capable of using glyphosate as P source were characterized by increases in the relative abundance of certain Bacteroidetes, Chloroflexi, Cyanobacteria, Planctomycetes and alpha-Proteobacteria members. Glyphosate-degrader candidates found in natural river biofilms can be further isolated for better understanding of glyphosate degradation pathways, and used as bioremediation strategies in heavily contaminated sites.

Glyphosate-based herbicide impairs energy metabolism and increases autophagy in C6 astroglioma cell line

ABSTRACTSeveral investigators demonstrated that glyphosate formulations produce neurotoxicity associated with oxidative stress, alterations in glutamatergic system, inhibition of acetylcholinesterase activity and mitochondrial dysfunction. However, the underlying molecular mechanisms following exposure to this herbicide on astrocytes are unclear. Thus, the aim of the present study was to determine the activity of enzymes related to energy metabolism, in addition to oxidative stress parameters, mitochondrial mass, nuclear area, and autophagy in astrocytes treated with a glyphosate-based herbicide. Our results showed that 24 h exposure to a glyphosate-based herbicide decreased (1) cell viability, (2) activities of mitochondrial respiratory chain enzymes and creatine kinase (CK), (3) mitochondrial mass, and (4) nuclear area in rat astroglioma cell line (C6 cells). However, non-protein thiol (NPSH) levels were increased but catalase activity was not changed in cells exposed to the herbicide at non-cytotoxic concentrations. Low glyphosate concentrations elevated content of cells positive to autophagy-related proteins. Nuclear factor erythroid 2-related factor (Nrf2), NAD(P)H dehydrogenase [quinone] 1 (NQO1) and PTEN-induced kinase 1 (PINK1) labeling were not markedly altered in cells exposed to glyphosate at the same concentrations that an increase in NPSH levels and positive cells to autophagy were found. It is conceivable that mitochondria and CK may be glyphosate-based herbicides targets. Further, autophagy induction and NPSH increase may be mechanisms initiated to avoid oxidative stress and cell death. However, more studies are needed to clarify the role of autophagy in astrocytes exposed to the herbicide and which components of the formulation might be triggering the effects observed here.

Biochemical and genotoxicity assessment of a polluted urban river using the native fish Astyanax altiparanae Garutti &amp; Britski (Teleostei, Characidae)

Agriculture residues and domestic effluents are contaminants that reach aquatic ecosystems leading to toxic effects to environment and human health. These contaminants impacting mainly developing countries, due to precarious treatment of effluents and lack of legislation in the use of pesticides. Perequê River (South of Brazil) is impacted by pesticides (mainly glyphosate) and domestic effluents. The aims of this study were to analyze the concentration of glyphosate in water and sediments of Perequê River; and to evaluate the sublethal effects of the river contamination in Astyanax altiparanae using biomarkers. A sampling of water, sediment and fish were carried out in Perequê River (November/2016). The samples were collected in two sites, site 1 (S1) that is located on agriculture area and water catchment point; and site 2 (S2) located on the area with a domestic effluents influence. Water and sediment samples were used to glyphosate quantification. Fish were collected and tissues (brain, muscle, liver) were used to biochemical and genetic biomarkers. Glyphosate were quantified in S1, which is impacted by agriculture. Alterations in the liver biomarkers were not observed between the sites. However, the decrease in the AChE activity was observed in the S2, showing that the mixture of contaminants (urban and agriculture contaminants) can lead to anticholinesterasic effects. The sublethal effects observed can be a threat of environmental and human health.