Ecotoxicological assessment of glyphosate-based herbicides: Effects on different organisms

Environmental concentrations of glyphosate through direct or parental exposure alter nervous system development and reduce the fertility rate in zebrafish

N-(phosphonomethyl)glycine (glyphosate) is the most widely used herbicide worldwide. Although it has been extensively studied, few studies use realistic environmental concentrations to assess its potential effects on fish embryos and larvae. This work aims to evaluate potential neurotoxic and reproductive effects of realistic concentrations of glyphosate in non-target aquatic species using zebrafish larvae. Biological and reproductive biomarkers (condition factor, hepatic and gonadic indices, and fertility rate) were evaluated for adults exposed to 0, 10, 100, and 1000 µg/L, while a transcriptomic comparison was carried out for larvae from both exposure scenarios at 1000 µg/L. The fertility rate of exposed parents decreased with increasing glyphosate concentration, while gonadosomatic (GSI) and hepatosomatic (HIS) indices of females treated with 100 µg/L glyphosate were significantly higher in glyphosate-exposed fish compared to the control group; however, glyphosate treatment did not significantly change GSI or HSI in males. Transcriptomic analysis in larvae showed that glyphosate could alter developmental and metabolic processes, targeting the nervous system in both exposure schemes. The ability of glyphosate to alter the development of the nervous system in larvae of exposed parents suggests that exposure to gametes could produce intergenerational alterations, with potential ecotoxicological implications that remain to be determined.

Effects of atrazine, diuron and glyphosate mixtures on zebrafish embryos: acute toxicity and oxidative stress responses

Synthetic pesticides are known for their toxic effects on non-target aquatic organisms. However, little is known about their effects when present in mixtures, which are closer to realistic exposure scenarios. Therefore, this study evaluates the toxicity of pesticides such as diuron, atrazine and glyphosate, individually and in combination, in zebrafish embryos, investigating their mechanisms of oxidative stress. The results revealed acute toxicity for diuron and atrazine, with LC50 values of 9.6 mg/L and 53.57 mg/L for 96-h-old zebrafish, respectively. On the other hand, no effect was observed for glyphosate alone at the maximum concentration tested (100 mg/L). The mixture of diuron and atrazine showed a synergistic effect, resulting in a decrease in the LC50 of each pesticide. Mixtures of diuron + glyphosate and atrazine + glyphosate were considered additive and antagonistic, respectively. All biomarkers analyzed (AChE, LDH, GST, CAT and GPx) showed significant changes. Furthermore, an increase in ROS production was observed in larvae exposed to individual and in the mixture composed of atrazine and diuron. These findings indicate that atrazine and diuron exhibit increased toxicity when combined, with their mechanisms of action-both in isolation and in mixtures-being at least partially linked to oxidative stress.

Controlled release of trifluralin herbicide using luminescent Vibrio-derived polyhydroxyalkanoate (PHA) microcapsules

The controlled release of herbicides using new and safe materials can mitigate environmental pollution. Polyhydroxyalkanoate (PHA) is a type of biopolymer that can be produced by various bacteria. It has properties that make it suitable for encapsulation and controlled release applications. A luminescent bacterium, Vibrio sp. VLC strain was used as the PHA producer in this study. Initially, the polymer was synthesized by the bacterium following optimization of the culture medium, resulting in an approximate yield of 25 %. Subsequently, the produced polymer was analyzed using TEM, FTIR, and H-NMR techniques. Microcapsules were produced using the emulsion method. FE-SEM imaging revealed spherical microcapsules with an average diameter of 0.5-2 μm. The herbicide loading content and encapsulation efficiency were determined to be 16.64 % and 66.56 %, respectively. The herbicidal effect of the microcapsules containing trifluralin was investigated using Amaranthus retroflexus and Setaria viridis plants, demonstrating a significant reduction in various parameters after application. Furthermore, the impact of encapsulated herbicide on soil microbial population was assessed, revealing a less negative effect compared to its free form. These findings suggest that the PHA from a luminescent vibrio holds promise as an eco-friendly, biodegradable, nontoxic material for the controlled release of herbicides.

Impact of glyphosate herbicide exposure on sperm motility, fertilization, and embryo-larval survival of pejerrey fish (Odontesthes bonariensis)

The herbicide glyphosate is widely used in agricultural practices around the world, can reach aquatic environments, and potentially impact non-target organisms. This study aimed to investigate the effects of glyphosate exposure (both as the active ingredient and its formulated product) on sperm quality, fertilization success, and development of pejerrey (Odontesthes bonariensis), a native freshwater fish species from Argentina. Results revealed a statistically significant increase in sperm motility at the highest concentration of the formulated product. In contrast, exposure to the active ingredient resulted in a decrease in certain motility parameters. Fertilization assays and embryonic development showed no notable effects in exposed groups. There were no effects in the morphology or temporal evolution of the embryonic stages, nor in the hatching rate. In contrast, larvae exposed to the formulated product exhibited a significant increase in mortality rates, reaching 100% mortality at the highest concentration within a few hours. These findings suggest differential susceptibility between embryos and larvae to glyphosate exposure and highlight the importance of simultaneously assessing the impacts of both the active ingredient and the entire formulation of glyphosate on freshwater fish reproduction and development.

A review of the influence of pH on toxicity testing of acidic environmental chemical pollutants in aquatic systems using zebrafish (Danio rerio) and glyphosate toxicity as a case study

Glyphosate is an acidic herbicide reported to contaminate water sources around the globe. Glyphosate alters the pH of a solution depending upon the concentration and buffering capacity of the solution in which it is present. Hence, toxicity observed in laboratory-based studies could be caused by the chemical or acidic pH if the solution is not adjusted to neutral conditions, confounding toxicity assessments. When reviewing zebrafish glyphosate toxicity studies, major discrepancies were noted among the published literature. Moreover, it was discovered that most of these studies did not mention pH or neutralization of the test solution. Thirty-six articles were identified when restricting the search from January 2009 through April 2024 to studies testing glyphosate toxicity (as glyphosate or glyphosate-based herbicides) in zebrafish and assessed for time of exposure, test concentrations, and mention or assessment of pH in exposure solutions. Additionally, toxicity curves for unadjusted pH and adjusted pH conditions for glyphosate were also determined in developing zebrafish from 1 to 120 hours post fertilization (hpf), to further clarify and support pH influence of glyphosate in these toxicity tests. Furthermore, a pH toxicity curve was established for the same developmental period to address if the divergence noted in the literature was based on glyphosate's influence on acidity of the exposure solution. Results showed that at concentrations greater than 10 ppm (mg/L), the pH of the water used in the experiments at chemistry parameters commonly used in zebrafish toxicity studies reduced to 5.5. As the glyphosate concentration increased, the pH continued to drop as low as 2.98. When comparing unneutralized and neutralized glyphosate solutions, the 120 hpf-LC50 without neutralization was close to 50 ppm, while minimal lethality was observed up to 1000 ppm in the neutralized solutions. Findings were then compared to the thirty-six zebrafish glyphosate toxicity studies for alignment of findings with glyphosate or pH toxicity. Eighteen of the studies included treatment concentrations less than 10 ppm with pH likely not to influence reported outcomes. Of the 18 remaining studies at higher concentrations likely to influence pH, only one reported neutralizing their exposure solutions. Two additional studies mentioned pH as a potential driving factor but did not repeat in neutral conditions. As a result, 17 of the 36 studies are observing primarily pH toxicity in the glyphosate assessments. Based on these findings, caution is warranted in interpreting results of acidic environmental contaminants in cases where pH of exposure solutions is not stated.

Green synthesis and evaluation of dual herb-extracted DHM-AgNPs: Antimicrobial efficacy and low ecotoxicity in agricultural and aquatic systems

Uncontrolled applications of weedicide and fertilizer can harm the soil ecology, and most significantly, earthworms are hazardous soil engineers. Thus, we aimed at the toxicity and histopathological alterations in the earthworm Eudrilus euginae following exposure to glyphosate (weedicide), urea (fertilizer), and environmentally friendly dual herb-mixed silver nanoparticles (DHM-AgNPs). The DHM-AgNPs were synthesized using a blend of Alfinia officinarum and Curcuma longa aqueous leaf extracts with 1 mM silver nitrate. The color change from yellow to brown after an hour of incubation was a significant indicator of successful DHM-AgNP synthesis. Characterization of the DHM-AgNPs using UV-Vis spectra indicated a surface plasmon resonance (SPR) peak at 430 nm. In addition to FT-IR spectroscopy and XRD analysis, SEM, TEM, and SEM investigations were performed to identify the DHM-AgNPs. The XPS analysis revealed the oxidation state and surface chemical composition, and Ag NP's specific surface area and degree of porosity were measured using BET. Furthermore, different concentrations of urea and glyphosate were administered to Artemia nauplii and E. euginae to assess their toxicity. The mortality rate for E. euginae exposed to a higher urea concentration (10 g/kg of soil) was 100%. In contrast, a % mortality rate of 83% was noted at 0.5 g/kg of soil. The maximum mortality (90 ± 0.64%) was observed at a 10 mL/kg/L concentration for glyphosate. In contrast, low mortality was noted in E. euginae and A. nauplii exposed with gradient concentrations of DHM-AgNPs compared to glyphosate and urea. As aquaculture and foodborne diseases are widespread, DHM-AgNPs showed significant anti-Vibrio activity against pathogenic Vibrio-related bacteria, inhibiting 80% at 100,100 μg/L, which is of great concern. This study suggests the potential use of DHM-AgNPs in field aqua and crops culture for eco-friendly pest control and anti-Vibrio activity without causing soil and environmental pollution. Further research is warranted to determine the efficacy, safety, and cost-effectiveness of DHM-AgNPs in aqua and agricultural practices.

Eco(geno)toxicity of an acaricidal formulation containing chlorpyrifos, cypermethrin, and fenthion on different plant models and Artemia salina L

The mixture of pesticides is widely employed in cattle farming to combat ectoparasite resistance, such as ticks. The commercial formulation COLOSSO FC30, which contains three active ingredients (Cypermethrin, Chlorpyrifos, and Fenthion), stands out due to its efficiency. However, animals exposed to this product may become vectors of potentially toxic molecules, possibly causing contamination in aquatic and terrestrial ecosystems. In light of this, this study evaluated the eco(geno)toxic potential of the commercial formulation COLOSSO FC30, using plants (Allium cepa L., Lactuca sativa L., Raphanus sativus L., Pennisetum glaucum L., and Triticum aestivum L.) and Artemia salina L. as model organisms. In the phytotoxicity test, the species were ranked in order of sensitivity to the commercial formulation as follows: P. glaucum > L. sativa > T. aestivum > R. sativus. The most sensitive parameters were root length (RL) and shoot length (SL) of seedlings. In the cytogenotoxicity test with A. cepa, cell division was decreased at concentrations from 0.351 mL L-1 in the meristematic region and root F1. Chromosomal aberrations and micronucleus were observed at all concentrations. In the test with A. salina, the IC50 after 24 h of exposure was 0.01207 mL L-1 of the commercial formulation. The results highlight the need for further research and regulations to understand and minimize the potential environmental impacts of COLOSSO FC30.

Effects of glyphosate-based herbicide on gut microbes and hepatopancreatic metabolism in Pomacea canaliculata

Roundup®, a prominent glyphosate-based herbicide (GBH), holds a significant position in the global market. However, studies of its effects on aquatic invertebrates, including molluscs are limited. Pomacea canaliculata, a large freshwater snail naturally thrives in agricultural environments where GBH is extensively employed. Our investigation involved assessing the impact of two concentrations of GBH (at concentrations of 19.98 mg/L and 59.94 mg/L, corresponding to 6 mg/L and 18 mg/L glyphosate) during a 96 h exposure experiment on the intestinal bacterial composition and metabolites of P. canaliculata. Analysis of the 16 S rRNA gene demonstrated a notable reduction in the alpha diversity of intestinal bacteria due to GBH exposure. Higher GBH concentration caused a significant shift in the relative abundance of dominant bacteria, such as Bacteroides and Paludibacter. We employed widely-targeted metabolomics analysis to analyze alterations in the hepatopancreatic metabolic profile as a consequence of GBH exposure. The shifts in metabolites primarily affected lipid, amino acid, and glucose metabolism, resulting in compromised immune and adaptive capacities in P. canaliculata. These results suggested that exposure to varying GBH concentrations perpetuates adverse effects on intestinal and hepatopancreatic health of P. canaliculata. This study provides an understanding of the negative effects of GBH on P. canaliculata and may sheds light on its potential implications for other molluscs.

Pesticide-induced alterations in zebrafish (Danio rerio) behavior, histology, DNA damage and mRNA expression: An integrated approach

To assess the impact of glyphosate and 2,4-D herbicides, as well as the insecticide imidacloprid, both individually and in combination, the gills of adult zebrafish were used due to their intimate interaction with chemicals diluted in water. Bioassays were performed exposing the animals to the different pesticides and their mixture for 96 h. The behavior of the fish was analyzed, a histological examination of the gills was carried out, and the genotoxic effects were also analyzed by means of the comet assay (CA) and the change in the expression profiles of genes involved in the pathways of the oxidative stress and cellular apoptosis. The length traveled and the average speed of the control fish, compared to those exposed to the pesticides and mainly those exposed to the mixture, were significantly greater. All the groups exposed individually exhibited a decrease in thigmotaxis time, indicating a reduction in the behavior of protecting themselves from predators. Histological analysis revealed significant differences in the structures of the gill tissues. The quantification of the histological lesions showed mild lesions in the fish exposed to imidacloprid, moderate to severe lesions for glyphosate, and severe lesions in the case of 2,4-D and the mixture of pesticides. The CA revealed the sensitivity of gill cells to DNA damage following exposure to glyphosate, 2,4-D, imidacloprid and the mixture. Finally, both genes involved in the oxidative stress pathway and those related to the cell apoptosis pathway were overexpressed, while the ogg1 gene, involved in DNA repair, was downregulated.

In vivo estrogenicity of glyphosate, its formulations, and AMPA on transgenic zebrafish (Danio rerio) embryos

In this study, the disrupting effects of glyphosate (GLY), aminomethylphosphonic acid (AMPA), and three glyphosate-based herbicides (GBHs) on vitellogenesis in a non-concentration-dependent manner are reported for the first time in 120 h of acute exposure of zebrafish at environmentally relevant concentrations. GBHs are commonly used worldwide in weed control management. Due to their extensive application, they frequently occur in aquatic ecosystems and may affect various organisms. The active substance GLY and its major by-product, AMPA, are the most thoroughly studied chemicals; however, the adverse effects of the complex formulas of GBHs with diverse and unknown content of co-formulants are still not sufficiently researched. This study focused on the embryotoxicity, sublethal malformations, and estrogenic potency of GLY, AMPA, and four commonly used GBHs on zebrafish embryos using a wild type and an estrogen-sensitive, transgenic zebrafish line (Tg(vtg1:mCherry)). After 120 h of exposition, AMPA did not cause acute toxicity, while the LC50 of GLY was 160 mg/L. The GBHs were more toxic with LC50 values ranging from 31 to 111 GLY active equivalent (a.e.) mg/L. Exposure to 0.35-2.8 mg/L GBHs led to sublethal abnormalities: typical symptoms were structural deformation of the lower jaw and anomalies in the olfactory region. Deformity rates were 10-30% in the treated groups. In vivo, fluorescently expressed vtg1 mCherry protein in embryonic liver was detected by a non-invasive microscopic method indicating estrogenic action through vitellogenin production by GLY, AMPA, and GBHs. To confirm the in vivo findings, RT-qPCR method was performed to determine the levels of the estrogenicity-related vtg1 mRNA. After 120 h of exposure to GLY, AMPA, and three GBHs at a concentration of 0.35 mg/L, the expression of vtg1 gene was significantly up-regulated. Our results highlight the risk that short-term GLY and GBH exposure can cause developmental malformations and disrupt the hormonal balance in zebrafish embryos.

Selection of aquatic microbiota exposed to the herbicides flufenacet and metazachlor

Herbicides are important, ubiquitous environmental contaminants, but little is known about their interaction with bacterial aquatic communities. Here, we sampled a protected natural freshwater habitat and characterised its microbiome in interaction with herbicides. We evolved the freshwater microbiomes in a microcosm assay of exposure (28 days) to flufenacet and metazachlor at environmental concentrations of 0.5, 5 and 50 μg L-1 . Inhibitory effects of herbicides were exemplarily assessed in cultured bacteria from the same pond (Pseudomonas alcaligenes, Paenibacillus amylolyticus and Microbacterium hominis). Findings were compared to long-term concentrations as provided by local authorities. Here, environmental concentrations reached up to 11 μg L-1 (flufenacet) and 76 μg L-1 (metazachlor). Bacteria were inhibited at minimum inhibitory concentrations far above these values; however, concentrations of 50 μg L-1 of flufenacet resulted in measurable growth impairment. While most herbicide-exposed microcosm assays did not differ from controls, Acidobacteria were selected at high environmental concentrations of herbicides. Alpha-diversity (e.g., taxonomic richness on phylum level) was reduced when aquatic microbiomes were exposed to 50 μg metazachlor or flufenacet. One environmental strain of P. alcaligenes showed resistance to high concentrations of flufenacet (50 g L-1 ). In total, this study reveals that ecologic imbalance due to herbicide use significantly impacts aquatic microbiomes.

Molecular and biochemical biomarkers in the American oyster Crassostrea virginica exposed to herbicide Roundup® at high temperature

Aquatic organisms are frequently exposed to various environmental stressors. Thus, the effects of high temperatures and herbicides on aquatic organisms are a major subject of interest. In this study, we studied the effects of short-term exposure (1 week) to Roundup®, a glyphosate-based herbicide (concentrations: 0.5 and 5 µg/L), on the morphology of gills, digestive glands, and connective tissues, and the expression of heat shock protein-70 (HSP70, a chaperone protein), cytochrome P450 (CYP450, a biomarker of environmental contaminants), dinitrophenyl protein (DNP, a biomarker of protein oxidation), nitrotyrosine protein (NTP, a biomarker of protein nitration), antioxidant enzymes such as superoxidase dismutase (SOD) and catalase (CAT) in tissues of American oyster, Crassostrea virginica (Gmelin, 1791) maintained at high temperature (30 °C). Histological analyses showed an increase in mucous production in the gills and digestive glands, and in hemocyte aggregation in the connective tissues as well as a structural change of lumen in the digestive glands of oysters exposed to Roundup. Immunohistochemical and quantitative RT-PCR analyses showed significant (P < 0.05) increases in HSP70, CYP450, DNP, NTP, CAT, and SOD mRNA and protein expressions in the tissues of oysters exposed to Roundup. Taken together, these results suggest that exposure to Roundup at high temperature induces overproduction of reactive oxygen species/reactive nitrogen species which in turn leads to altered prooxidant-antioxidant activity in oyster tissues. Moreover, our results provide new information on protein oxidation/nitration and antioxidant-dependent mechanisms for HSP70 and CYP450 regulations in oysters exposed to Roundup at high temperature.

Characterization of glyphosate-induced cardiovascular toxicity and apoptosis in zebrafish

Glyphosate, the most widely used herbicide, presents new hazards to human health. The developmental toxicity of glyphosate, especially its cardiovascular toxicity, needs to be closely monitored. To understand how glyphosate affects development, we performed toxicity tests on zebrafish embryos that were continuously exposed to glyphosate. The results indicated that glyphosate affected the overall development of zebrafish embryos, including mortality, hatching abnormalities, and decreased body length. At the same time, zebrafish embryos exposed to glyphosate exhibited cardiac malformations, including enlarged chambers, thinned ventricular walls, and rhythm disturbances. In addition, defective intersegmental vasculature occurred after glyphosate exposure, indicating impaired angiogenesis. Mechanistically, apoptosis clustered in the heart and vascular regions and levels of ATP and apoptosis-related genes including caspase-3, caspase-9, bax, and bcl-2 were altered. In summary, the data showed that cardiovascular toxicity caused by glyphosate exposure may be related to apoptosis. Our study provides evidence for a link between glyphosate exposure and cardiovascular developmental toxicity. This raises concerns regarding the health risks of the glyphosate.

Effects of the herbicide glyphosate on fish from embryos to adults: a review addressing behavior patterns and mechanisms behind them

The use of agrochemicals has grown in recent years following the increase in agricultural productivity, to eliminate weeds that can compromise crop yields. The intensive use of these products combined with the lack of treatment of agricultural wastewater is causing contamination of the natural environments, especially the aquatics. Glyphosate [N-(phosphonomethyl) glycine] is the most commonly used herbicide in agriculture worldwide. Studies have shown that this compound is toxic to a variety of fish species at the concentrations of environmental relevance. Glyphosate-based herbicides can affect fish biochemical, physiological, endocrine, and behavioral pathways. Changes in behaviors such as foraging, escaping from predators, and courtship can compromise the survival of species and even communities. The behavior patterns of fish has been shown to be a sensitive tool for risk assessment. In this sense, this review summarizes and discusses the toxic effects of glyphosate and its formulations on the behavior of fish in different life stages. Additionally, behavioral impairments were associated with other negative effects of glyphosate such as energy imbalance, stress responses, AChE inhibition, and physiological and endocrine disturbances, which are evidenced and described in the literature. Graphical abstract.

Effects of glyphosate on zebrafish: a systematic review and meta-analysis

Glyphosate herbicide is widely used in worldwide crop production. Consequently, its active ingredient, surfactants, and adjuvants commonly reach the aquatic ecosystem, thereby harming the biota. An investigation into how this herbicide affects aquatic species is important, especially in fish, as they have the ability to absorb and concentrate toxins. We aimed to evaluate the effects of glyphosate on the embryonic, larval and adult stages of zebrafish (Danio rerio), an appreciable organismal model. In this sense, we performed a meta-analysis using published articles from online databases (PubMed and ScienceDirect), which covered studies published until 2022. From a massive compilation of studies evaluating the effects of active substance glyphosate and Glyphosate-Based Herbicides (GBH) on zebrafish, we selected 36 studies used in downstream analyses. Overall, we report that glyphosate affects developmental stages and demonstrates toxicity and damage in zebrafish. We observed that embryos exposed to glyphosate exhibit increased mortality. There was also an increase in the number of morphological abnormalities related to yolk sac oedema, pericardial oedema, spinal curvature and body malformations, and a decrease in body size was observed. Furthermore, there was a decrease in the number of beats. The biochemical results demonstrated an increase in reactive oxygen species and antioxidant capacity against peroxyl radicals in the gills. The literature shows that glyphosate decreased the distance covered and the mean speed of the animals and increased the number of rotations. We concluded that glyphosate causes damage in the embryonic, larval and adult stages of this species. These results are valid for zebrafish and can be applied to other freshwater fish species. Graphical abstract.

Transcriptomic signaling in zebrafish (Danio rerio) embryos exposed to environmental concentrations of glyphosate

Glyphosate [N-(phosphonomethyl)glycine] is one of the most popular herbicides worldwide. Globally, the use of glyphosate is increasing, and its residues have been found in drinking water and food products. The data regarding the possible toxic effects of this herbicide are controversial. Therefore, the aim of this study was to evaluate the effects of glyphosate at environmental concentrations in zebrafish (Danio rerio) embryos. Embryos were exposed to 0, 1, 100, and 1,000 µg/L glyphosate for 96 h, and mortality, heart rate, and hatching rate were evaluated. After the experiment, RNA was extracted from the embryos for transcriptional analysis. No mortality was recorded, and exposure to 100 µg/L and 1,000 µg/L of glyphosate resulted in lower heart rates at 48 h. In addition, RNA-seq analysis revealed that glyphosate exposure induced subtle changes in gene transcription profiles. We found 30 differentially expressed genes; however, the highest glyphosate concentration (1,000 µg/L) induced the greatest number of differentially expressed genes involved in oocyte maturation, metabolic processes, histone deacetylation, and nervous system development.

In vitro and in vivo cytotoxicity assessment of glyphosate and imazethapyr-based herbicides and their association

Resistance to glyphosate herbicide has initiated usage of combined application of herbicides as a weed control measure. Imazethapyr-based herbicides associated with glyphosate herbicide seem to be an alternative to suppress weed resistance. The aim of this study was to examine the adverse effects of Glyphosate Atanor 48® (ATN) and Imazethapyr Plus Nortox® (IMZT) formulations in both single forms and mixtures using HepG2 cells and zebrafish early-life stages models. Data demonstrated cytotoxicity due to exposure to ATN, IMZT for both models, as follows: (1) ATN (0.5 mg/L), IMZT (5 mg/L), and M3 (0.05 mg/L ATN + 5 mg/L IMZT) increased cytotoxicity by disturbing the mitochondrial activity of HepG2 cells 24 hr after exposure; (2) ATN and IMZT (5 mg/L), and M3 (0.05 mg/L ATN + 5 mg/L IMZT) also decreased the integrity of the membrane of HepG2 cells after 24 hr incubation; (3) only ATN and IMZT (5 mg/L) in their single forms diminished the mitochondrial potential of zebrafish; (4) ATN (single form) at 0.5 mg/L induced apoptosis in zebrafish larvae. In conclusion, these herbicides in their single forms appeared to produce greater cytotoxicity to HepG2 cells and zebrafish compared to the herbicide mixtures.

Developmental toxicity of glyphosate on embryo-larval zebrafish (Danio rerio)

Glyphosate (GLY) induces developmental toxicity in fish, but research on the toxicity mechanism is limited. In this study, zebrafish embryos were exposed for 120 hpf to 0.7, 7, and 35 mg L-1 GLY. The results show that GLY treatment induced developmental toxicity in the fish, including premature hatching, reduced heartbeats, pericardial and yolk sac oedema, swim bladder deficiency, and shortened body length, which was possibly due to a significantly decreased triiodothyronine (T3)/thyroxine (T4) ratio and the abnormal expression patterns of hypothalamic-pituitary-thyroid (HPT) (crh, tshβ, tr α, tr β, and t tr ) and growth hormone/insulin-like growth factor (GH/IGF) axis-related genes (gh, ghrα, ghrβ, igf1, igf1rα, and igf1rβ) in larvae exposed to GLY. In addition, GLY exposure altered the levels of SOD and CAT, increased ROS, promoted malondialdehyde (MDA) content, and significantly altered the levels of endoplasmic reticulum (ER) stress signalling pathway factors (perk, eif2α, gadd34, atf4, ire1α, xbp1, atf6, hspa5, and chop), suggesting that GLY treatment induced oxidative injury and ER stress in the larvae. Further research showed that treatment with a higher concentration of GLY upregulated the levels of iNOS, IL-1β, and TNF-α while inhibiting the expression of IL-10 and TGF-β, suggesting that GLY causes an inflammatory reaction in the larvae. In addition, we also found that apoptosis was induced in the larvae, which was determined by acridine orange staining and abnormal expression of p53, caspase-3, -8, and -9. Taken together, our results demonstrate that GLY exposure altered the T3/T4 ratio, disturbed the expression patterns of HPT and GH/IGF axis-related genes, and induced oxidative and ER stress, inflammatory reactions, and apoptosis in the zebrafish larvae. This investigation contributes to improved understanding of the developmental toxicity mechanism of GLY in fish.

Toxic Effects of Glyphosate on the Nervous System: A Systematic Review

Glyphosate, a non-selective systemic biocide with broad-spectrum activity, is the most widely used herbicide in the world. It can persist in the environment for days or months, and its intensive and large-scale use can constitute a major environmental and health problem. In this systematic review, we investigate the current state of our knowledge related to the effects of this pesticide on the nervous system of various animal species and humans. The information provided indicates that exposure to glyphosate or its commercial formulations induces several neurotoxic effects. It has been shown that exposure to this pesticide during the early stages of life can seriously affect normal cell development by deregulating some of the signaling pathways involved in this process, leading to alterations in differentiation, neuronal growth, and myelination. Glyphosate also seems to exert a significant toxic effect on neurotransmission and to induce oxidative stress, neuroinflammation and mitochondrial dysfunction, processes that lead to neuronal death due to autophagy, necrosis, or apoptosis, as well as the appearance of behavioral and motor disorders. The doses of glyphosate that produce these neurotoxic effects vary widely but are lower than the limits set by regulatory agencies. Although there are important discrepancies between the analyzed findings, it is unequivocal that exposure to glyphosate produces important alterations in the structure and function of the nervous system of humans, rodents, fish, and invertebrates.

Phytotoxic and cytogenotoxic assessment of glyphosate on Lactuca sativa L

The active ingredient glyphosate is the most commercialized herbicide on the world market due to its capability in eliminating weeds. However, it can harm the development of non-target organisms and threaten environmental quality. This study analyzed the effects of potentially toxic concentrations of glyphosate on germination, growth, cell cycle and genomic stability of Lactuca sativa L., and identified the most sensitive variables for assessing the toxicity of this herbicide to this biomonitor. Seeds of L. sativa were germinated in Petri dishes containing a sheet of filter paper moistened with 5 mL of a concentration of glyphosate (1.34, 3.35, 6.70, 10.05, 13.40 mg L-1). Controls consisted of distilled water (negative) and 3 mg L-1 CuSO4 (positive). Macroscopic and microscopic variables were analyzed. The germination of L. sativa was not affected by the concentrations of glyphosate. Root length and shoot height of the plants and the mitotic index decreased from the lowest concentration tested on. The chromosomal anomaly index and frequency of micronuclei increased by 3.2 and 22 times, respectively, with the presence of the lowest concentration of glyphosate compared to the negative control. The observed phytotoxic and cytogenotoxic effects demonstrate the negative influence that glyphosate has on the development of L. sativa. Root length and microscopic variables showed the highest sensitivity. This study warns of the possible harmful effects that glyphosate can have on non-target organisms and suggests greater control over the use of this herbicide to mitigate its environmental impact.

Pesticide sensitivity of Nothobranchius neumanni, a temporary pond predator with a non-generic life-history

Pesticides are crucial to improve agricultural productivity, but often adversely affect surrounding aquatic systems and their fauna. To determine the environmental risk of pesticides, routine ecotoxicological tests are performed on several organisms, including standard fish models. However, these typically do not include fish species from variable habitats and with non-generic life-histories. In particular, inhabitants from temporary ponds such as annual killifish are conventionally understood to be resilient to natural stressors which could translate to higher pesticide resistance or, alternatively, trade-off with their resistance to pesticides and render them more sensitive than classic fish models. Using standard exposure tests, we assessed short-term toxicity effects of two commonly used pesticides, Roundup and cypermethrin, on the annual killifish Nothobranchius neumanni, and compared its sensitivity with that of classic fish models. For Roundup, we found a 72 h-LC₅₀ of 1.79 ± 0.11 mg/L, which is lower than the values reported for zebrafish, medaka, fathead minnow and rainbow trout, suggesting that N. neumanni is more sensitive to the compound. The opposite was true for cypermethrin, with a 72 h-LC₅₀ of 0.27 ± 0.03 mg/L. However, these LC₅₀-values do not deviate strongly from those reported for other fish species, supporting earlier findings in the congeneric N. furzeri that the sensitivity of annual killifish to pollutants is similar to that of classic fish models despite their assumed robustness to environmental stress.

Acute exposition to Roundup Transorb® induces systemic oxidative stress and alterations in the expression of newly sequenced genes in silverside fish (Odontesthes humensis)

Roundup Transorb® (RDT) is a glyphosate-based herbicide commonly used in agricultural practices worldwide. This herbicide exerts negative effects on the aquatic ecosystem and affects bioenergetic and detoxification pathways, oxidative stress, and cell damage in marine organisms. These effects might also occur at the transcriptional level; however, the expression of genes associated with oxidative stress has not been studied well. Odontesthes humensis is a native Brazilian aquatic species naturally distributed in the habitats affected by pesticides, including Roundup Transorb® (RDT). This study evaluated the toxic effects of short-term exposure to RDT on O. humensis. Moreover, the genes related to oxidative stress were sequenced and characterized, and their expressions in the gills, hepatopancreas, kidneys, and brain of the fish were quantified by quantitative reverse transcription-polymerase chain reaction. The animals were exposed to two environmentally relevant concentrations of RDT (2.07 and 3.68 mg L^-1) for 24 h. Lipid peroxidation, reactive oxygen species (ROS), DNA damage, and apoptosis in erythrocytes were quantified by flow cytometry. The expression of the target genes was modulated in most tissues in the presence of the highest tested concentration of RDT. In erythrocytes, the levels of lipid peroxidation, ROS, and DNA damage were increased in the presence of both the concentrations of RDT, whereas cell apoptosis was increased in the group exposed to 3.68 mg L^-1 RDT. In conclusion, acute exposure to RDT caused oxidative stress in the fish, induced negative effects on cells, and modulated the expression of genes related to the enzymatic antioxidant system in O. humensis.

The Influence of Herbicides to Marine Organisms Aliivibrio fischeri and Artemia salina

The aim of this work was to determine the toxic effect of the most used herbicides on marine organisms, the bacterium Aliivibrio fischeri, and the crustacean Artemia salina. The effect of these substances was evaluated using a luminescent bacterial test and an ecotoxicity test. The results showed that half maximal inhibitory concentration for A. fischeri is as follows: 15minIC50 (Roundup® Classic Pro) = 236 μg·L-1, 15minIC50 (Kaput® Premium) = 2475 μg·L-1, 15minIC50 (Banvel® 480 S) = 2637 μg·L-1, 15minIC50 (Lontrel 300) = 7596 μg·L-1, 15minIC50 (Finalsan®) = 64 μg·L-1, 15minIC50 (glyphosate) = 7934 μg·L-1, 15minIC50 (dicamba) = 15,937 μg·L-1, 15minIC50 (clopyralid) = 10,417 μg·L-1, 15minIC50 (nonanoic acid) = 16,040 μg·L-1. Median lethal concentrations for A. salina were determined as follows: LC50 (Roundup® Classic Pro) = 18 μg·L-1, LC50 (Kaput® Premium) = 19 μg·L-1, LC50 (Banvel® 480 S) = 2519 μg·L-1, LC50 (Lontrel 300) = 1796 μg·L-1, LC50 (Finalsan®) = 100 μg·L-1, LC50 (glyphosate) = 811 μg·L-1, LC50 (dicamba) = 3705 μg·L-1, LC50 (clopyralid) = 2800 μg·L-1, LC50 (nonanoic acid) = 7493 μg·L-1. These findings indicate the need to monitor the herbicides used for all environmental compartments.

Exposure to sublethal concentrations of the glyphosate-based herbicide Faena® increases sensitivity in the progeny of the American cladoceran Daphnia exilis (Herrick, 1895)

The use of herbicides has increased over the last decades. Glyphosate is the most widely used herbicide commercialized in more than 750 formulations. While information about glyphosate's toxicity on different non-target aquatic organisms has been vastly documented, we know little about the transgenerational effects in aquatic biota. This study determined the cross-generation effects produced by the glyphosate-based herbicide Faena® on the American cladoceran Daphnia exilis. Measured endpoints were survival, reproductive responses, metabolic biomarkers, and the size of neonates. D. exilis was exposed to glyphosate concentrations of 2.09, 2.49, and 3.15 (mg L-1) (as content in Faena®) during 21 days starting from neonates, at 25°C, 16:8 photoperiod, fed with 8 × 105 cells mL-1 of Pseudokirchneriella subcapitata. The LC50 was 4.22 mg L-1. Survival, accumulated progeny, and the number of clutches in the parental generation (P1) were significantly higher than those observed in the first generation (F1). Exposure to the herbicide completely inhibited reproduction in the F1. The size of the neonates varied among treatments and broods in P1; nevertheless, neonate size (body and total lengths, as well as body width) was significantly affected in F1. Toxic effects on the survival and reproduction of D. exilis were significantly increased in the F1 exposed to Faena®. Results warn about the augmented effect on progeny where parents were exposed to this herbicide. Multigenerational adverse effects could be expected in freshwater zooplankton exposed to Faena®. The frequently claimed low toxicity of glyphosate must be revised to control the indiscriminate use of this herbicide.

Identification of lncRNA expression profiles and analysis of ceRNA in the hippocampus of perinatal glyphosate-exposed mice

OBJECTIVE

In order to understand the role of long noncoding RNAs (lncRNAs) played in the mechanisms of glyphosate neurotoxicity in neuronal development.

METHODS

Perinatal glyphosate exposure (PGE) mouse model was constructed, and a lncRNA microarray was used to study the lncRNA expression changes in the hippocampus tissue of perinatal glyphosate exposure mice. Then we used GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) databases to analyze the function of the differentially expressed mRNAs and lncRNAs.

RESULTS

LncRNA microarray analysis revealed that 1759 lncRNAs and 759 mRNAs were differentially expressed in the perinatal glyphosate exposure (PGE) mice group (G group) compared with the normal control mice group (C group). The functions of the DEmRNAs are involved in the cellular response to hormone stimulus. The ceRNA analysis showed that some interaction networks existed, including (ENSMUST00000137546, ENSMUST00000160950)/(miR-34a-3p, miR-130a-3p)/(Il12b, Irf1). Further analysis of the target mRNAs of miRNAs indicated that the possible functions involved the neuroactive ligand-receptor interaction and calcium signaling pathway, which are involved in perinatal glyphosate exposure-induced neurotoxicity.

CONCLUSION

The aberrant expression of lncRNAs is related to the perinatal glyphosate-exposed neurotoxicity. These lncRNAs affect the target gene expression level, might by regulating neuroactive ligand-receptor interactions. The (ENSMUST00000137546, ENSMUST00000160950)/ (miRNA-34a-5p, miR-130a-3p) / mRNAs (e.g., Il12b, Irf1) interaction network may functions in perinatal glyphosate exposure-induced neurotoxicity.

Anti-angiogenic effects of beta-eudesmol and atractylodin in developing zebrafish embryos

Angiogenesis is the process of formation of new blood vessels which plays an essential role in the normal physiological development of the organs and systems. Several factors contribute to and regulate this process. Unregulated angiogenesis, however, is harmful and is usually found in tumors and cancerous cells. β-Eudesmol and atractylodin are sesquiterpenoid contents extracted from the rhizome of Atractylodes lancea (AL). Reports suggest potential anti-angiogenic activities of both compounds. In this study, the anti-angiogenic activities of both compounds were investigated using the well-established zebrafish in vivo model. Zebrafish embryos were treated with a series of concentrations (6.3, 12.5, 25, and 50 μM) of β-eudesmol and (6.3, 12.5, and 25 μM) of atractylodin up to 72 h post-fertilization. Assessment of the effects on phenotypic blood vessel development (sub-intestinal vessel intersection count) revealed that both the compounds inhibited vessel development, particularly at higher concentrations. At the genetic levels, only β-eudesmol significantly downregulated the expression of the Vegfaa gene and also its receptor Vegfr2. β-Eudesmol also affected the expression of Vegfaa protein in a concentration-dependent manner. Results indicate that β-eudesmol exerts anti-angiogenic property through inhibition of Vegfaa at both the gene and protein levels. However, atractylodin does not possess this property.

Glyphosate Herbicide Induces Changes in the Growth Pattern and Somatic Indices of Crossbred Red Tilapia (O. niloticus × O. mossambicus)

Simple Summary

In this study, a chronic, seven-week study of the effect of technical grade glyphosate on the toxicity parameters of crossbred red tilapia (O. niloticus × O. mossambicus) was carried out. The results show that the bodyweight index was the most sensitive toxicity parameter wherein a reduction in body weight was observed at 25 mg/L of glyphosate. Negative correlations between the glyphosate concentration and toxicity parameters such as specific growth rate (SGR), hepato-somatic index (HIS), and gonado-somatic index (GSI) were observed. The fish condition factor and feed conversion ratio were found to be unaffected at the highest glyphosate concentration tested (150 mg/L).

Abstract

The development of glyphosate-resistant genetically modified organisms (GMO) has increased the use of herbicide glyphosate by several magnitudes in recent years. It is now the most commonly used pesticide globally that affects aquatic habitats, especially fish. This study aims to add new knowledge on the effect of technical grade glyphosate on several toxicity parameters and to identify the most effective parameter in predicting technical grade glyphosate chronic toxicity (seven weeks) to fish, especially Malaysia’s heavily farmed red tilapia. The results show that a relatively high concentration of technical grade glyphosate is needed to induce significant changes in all tested parameters. However, the results also indicate that the bodyweight index is the most sensitive toxicity parameter in that a reduction in body weight was observed at 25 mg/L of glyphosate. Negative correlations between the glyphosate concentration and toxicity parameters such as specific growth rate (SGR), hepato-somatic index (HIS), and gonado-somatic index (GSI) were observed. The fish condition factor and feed conversion ratio were found not to be affected at the highest glyphosate concentration tested (150 mg/L). To conclude, crossbred red tilapia (O. niloticus × O. mossambicus) is one potential species for evaluating the toxic effects of technical grade glyphosate on fish.

Effects of commercial formulations of glyphosate on marine crustaceans and implications for risk assessment under temperature changes

Glyphosate-based formulations are the most commonly used herbicides worldwide with the risk of potential contamination of aquatic bodies. The present study assessed the response of four marine crustaceans to three different brands of herbicides Roundup®Platinum, Efesto® and Taifun® MK CL.T, under two selected temperatures of 20 °C and 30 °C. The harpacticoid copepod Tigriopus fulvus, the anostracan Artemia franciscana, the amphipod Corophium insidiosum and the isopod Sphaeroma serratum were chosen as testing organisms. Effects of herbicides and temperatures were assessed by estimating lethal concentrations. The results showed that the high temperature rises the toxicity of glyphosate with an increase of mortality of all the tested species. This is an important aspect for future risk assessments of pesticides under global climate change scenarios. Efesto® resulted the most toxic brand, showing C. insidiosum the most sensitive with 96 h-LC50 values of 3.25 mg/L acid equivalent (a.e.) at 30 °C and 7.94 mg/L a.e. at 20 °C followed by T. fulvus while A. franciscana and S. serratum were the less sensitive. This study provides important information for assessing the toxic effects of three different brands of glyphosate-based herbicides on non-target marine organisms suggesting that they should be carefully managed to minimize any negative impact on marine organisms.

Zebrafish (Danio rerio) using as model for genotoxicity and DNA repair assessments: Historical review, current status and trends

Genotoxic pollutants lead to both DNA damage and changes in cell repair mechanisms. Selecting suitable biomonitors is a fundamental step in genotoxicity studies. Thus, zebrafish have become a popular model used to assess the genotoxicity of different pollutants in recent years. They have orthologous genes with humans and hold almost all genes involved in different repair pathways. Therefore, the aim of the current study is to summarize the existing literature on zebrafish using as model system to assess the genotoxicity of different pollutants. Revised data have shown that comet assay is the main technique adopted in these studies. However, it is necessary standardizing the technique applied to zebrafish in order to enable better result interpretation and comparisons. Overall, pollutants lead to single-strand breaks (SSB), double-strand breaks (DSB), adduct formation, as well as to changes in the expression of genes involved in repair mechanisms. Although analyzing repair mechanisms is essential to better understand the genotoxic effects caused by pollutants, few studies have analyzed repair capacity. The current review reinforces the need of conducting further studies on the role played by repair pathways in zebrafish subjected to DNA damage. Revised data have shown that zebrafish are a suitable model to assess pollutant-induced genotoxicity.

Glyphosate and AMPA Induce Alterations in Expression of Genes Involved in Chromatin Architecture in Human Peripheral Blood Mononuclear Cells (In Vitro)

We have determined the effect of glyphosate and aminomethylphosphonic acid (AMPA) on expression of genes involved in chromatin architecture in human peripheral blood mononuclear cells (PBMCs). The cells were incubated with glyphosate and AMPA in the concentrations ranging from 0.5 to 100 μM and from 0.5, to 250 μM, respectively. The expression profile of the following genes by quantitative Real-Time PCR was evaluated: Genes involved in the DNA methylation (DNMT1, DNMT3A) and DNA demethylation process (TET3) and those involved in chromatin remodeling: genes involved in the modification of histone methylation (EHMT1, EHMT2) and genes involved in the modification of histone deacetylation (HDAC3, HDAC5). Gene profiling showed that glyphosate changed the expression of DNMT1, DMNT3A, and HDAC3, while AMPA changed the expression of DNMT1 and HDAC3. The results also revealed that glyphosate at lower concentrations than AMPA upregulated the expression of the tested genes. Both compounds studied altered expression of genes, which are characteristic for the regulation of transcriptionally inactive chromatin. However, the unknown activity of many other proteins involved in chromatin structure regulation prevents to carry out an unambiguous evaluation of the effect of tested xenobiotics on the studied process. Undoubtedly, we have observed that glyphosate and AMPA affect epigenetic processes that regulate chromatin architecture.

Roundup negatively impacts the behavior and nerve function of the Madagascar hissing cockroach (Gromphadorhina portentosa)

Glyphosate is the active ingredient in Roundup formulations. Glyphosate-based herbicides are used globally in agriculture, forestry, horticulture, and in urban settings. Glyphosate can persist for years in our soil, potentially impacting the soil-dwelling arthropods that are primary drivers of a suite of ecosystem services. Furthermore, although glyphosate is not generally classified as neurotoxic to insects, evidence suggests that it may cause nerve damage in other organisms. In a series of experiments, we used food to deliver environmentally realistic amounts of Roundup ready-to-use III, a common 2% glyphosate-based herbicide formulation that lists isopropylamine salt as its active ingredient, to Madagascar hissing cockroaches. We then assessed the impact of contamination on body mass, nerve health, and behavior. Contaminated food contained both 30.6 mg glyphosate and so-called inert ingredients. Food was refreshed weekly for 26-60 days, depending on the experiment. We found that consumption of contaminated food did not impact adult and juvenile survivorship or body weight. However, consumption of contaminated food decreased ventral nerve cord action-potential velocity by 32%, caused a 29% increase in respiration rate, and caused a 74.4% decrease in time spent on a motorized exercise wheel. Such changes in behavior may make cockroaches less capable of fulfilling their ecological service, such as pollinating or decomposing litter. Furthermore, their lack of coordination may make them more susceptible to predation, putting their population at risk. Given the decline of terrestrial insect abundance, understanding common risks to terrestrial insect populations has never been more critical. Results from our experiments add to the growing body of literature suggesting that this popular herbicide can act as a neurotoxin.

Thymol-Loaded Biogenic Silica Nanoparticles in an Aquatic Environment: The Impact of Particle Aggregation on Ecotoxicity

Thymol, a monoterpene phenol, is used as a natural biocide. To circumvent its chemical instability, we propose use of thymol-loaded biogenic silica nanoparticles (BSiO₂ #THY NPs); however, the toxicity of this system for aquatic organisms is unknown. Thus, the present study aimed to evaluate the toxicogenetic effects induced by thymol, BSiO₂ NP, and BSiO₂ #THY on Artemia salina and zebrafish (Danio rerio) early life stages. We also investigated the impact of BSiO₂ aggregation in different exposure media (saline and freshwater). Based on the median lethal concentration at 48 h (LC50_48h ), BSiO₂ #THY (LC50_48h  = 1.06 mg/L) presented similar toxic potential as thymol (LC50_48h  = 1.03 mg/L) for A. salina, showing that BSiO₂ had no influence on BSiO₂ #THY toxicity. Because BSiO₂ aggregated and sedimented faster in A. salina aqueous medium than in the other medium, this NP had lower interaction with this microcrustacean. Thus, BSiO₂ #THY toxicity for A. salina is probably due to the intrinsic toxicity of thymol. For zebrafish early life stages, BSiO₂ #THY (LC50_96h  = 13.13 mg/L) was more toxic than free thymol (LC50_96h  = 25.60 mg/L); however, BSiO₂ NP has no toxicity for zebrafish early life stages. The lower aggregation of BSiO₂ in the freshwater medium compared to the saline medium may have enhanced thymol's availability for this aquatic organism. Also, BSiO₂ #THY significantly induced sublethal effects as thymol, and both were genotoxic for zebrafish. In conclusion, although BSiO₂ #THY still needs improvements to ensure its safety for freshwater ecosystems, BSiO₂ NP seems to be a safe nanocarrier for agriculture. Environ Toxicol Chem 2021;40:333-341. © 2020 SETAC.

Gene expression response of the alga Fucus virsoides (Fucales, Ochrophyta) to glyphosate solution exposure

Fucus virsoides is an ecologically important canopy-forming brown algae endemic to the Adriatic Sea. Once widespread in marine coastal areas, this species underwent a rapid population decline and is now confined to small residual areas. Although the reasons behind this progressive disappearance are still a matter of debate, F. virsoides may suffer, like other macroalgae, from the potential toxic effects of glyphosate-based herbicides. Here, through a transcriptomic approach, we investigate the molecular basis of the high susceptibility of this species to glyphosate solution, previously observed at the morphological and eco-physiological levels. By simulating runoff event in a factorial experiment, we exposed F. virsoides to glyphosate (Roundup® 2.0), either alone or in association with nutrient enrichment, highlighting significant alterations of gene expression profiles that were already visible after three days of exposure. In particular, glyphosate exposure determined the near-complete expression shutdown of several genes involved in photosynthesis, protein synthesis and stress response molecular pathways. Curiously, these detrimental effects were partially mitigated by nutrient supplementation, which may explain the survival of relict population in confined areas with high nutrient inputs.

Screening of Allelochemicals in Miscanthus sacchariflorus Extracts and Assessment of Their Effects on Germination and Seedling Growth of Common Weeds

There is increasing interest in the application of bioherbicides because they are less destructive to the global ecosystem than synthetic herbicides. Research has focused on reducing the dependence upon synthetic herbicides by substituting them with environmentally and economically sustainable bioproducts. Allelopathic phytochemicals may be an efficient method for controlling weeds, benefitting both the environment and human health. This study addressed the allelopathic potential of Miscanthus sacchariflorus (MS) extracts on the germination, plant growth, biomass, and biochemical parameters (electrolyte leakage, photosynthetic pigments, and antioxidant enzyme activities) of weeds using laboratory and field experiments. Liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) showed the presence of 22 phenolic compounds, including Orientin, Luteolin, Veratric acid, Chlorogenic acid, Protocatechuic acid, p-Coumaric acid, and Ferulic acid. Leaf extracts of M. sacchariflorus either completely suppressed or partially reduced seed germination and affected the development of weed seedlings (root and shoot length), in a dose-dependent manner. Aqueous extracts of M. sacchariflorus reduced the fresh weight and dry weight, affected the photosynthetic pigment content (chlorophylls, carotenoids), influenced the electrolyte ion leakage, and stimulated the activity of antioxidant enzymes in a species-specific manner. Pearson's correlation analysis showed that the phenolic compound composition of M. sacchariflorus correlated with the variables tested, indicating that the phytochemicals present in the plant extracts of M. sacchariflorus are a potential source of bio-herbicides.

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.

The Effects of Glyphosate and Its Commercial Formulations to Marine Invertebrates: A Review

Glyphosate is the active ingredient of numerous commercial formulations of herbicides applied in different sectors, from agriculture to aquaculture. Due to its widespread use around the world, relatively high concentrations of glyphosate have been detected in soil and aquatic environments. The presence of glyphosate in aquatic ecosystems has aroused the attention of researchers because of its potential negative effects on living organisms, both animals and plants. In this context, this review intends to summarize results of studies aimed at evaluating the effects of glyphosate (both as active ingredient and component of commercial formulations) on marine invertebrates. Generally, data obtained in acute toxicity tests indicate that glyphosate and its commercial formulations are lethal at high concentrations (not environmentally realistic), whereas results of long-lasting experiments indicate that glyphosate can markedly affect biological responses of marine invertebrates. Consequently, more efforts should be addressed at evaluating chronic or sub-chronic effects of such substances to marine invertebrate species.

Interference of goethite in the effects of glyphosate and Roundup® on ZFL cell line

Goethite (α-FeOOH) brings important perspectives in environmental remediation, as, due to its physicochemical properties, this iron oxide can adsorb a wide variety of compounds, including glyphosate. This study aimed to evaluate the effects of goethite nanoparticles (NPs), glyphosate (Gly), Roundup® (Rd), and co-exposures (Gly + NPs and Rd + NPs) on zebrafish liver cell line (ZFL). ZFL cells were exposed to NPs (1, 10, and 100 mg L-1), Gly (3.6 mg L-1), Rd (10 mg L-1), and co-exposures (Gly + NPs and Rd + NPs), or only to saline for 1, 6, and 12 h. Cell viability was assessed by Trypan blue, MTT, and neutral red assays. The generation of reactive oxygen species and total antioxidant capacity were also determined, while genotoxicity was quantified by the comet assay. Both NPs and Rd in isolation produced cytotoxic effects at 6 h and genotoxic effects at 1 and 6 h. Rd + NPs resulted in synergistic effects, intensifying the toxicity. Cells exposed to Gly did not present toxic effects and Gly + NPs resulted in the suppression of toxic effects observed for NPs. The presence of other components in Roundup® seems to favor its toxicity compared to the active ingredient. In conclusion, according to the in vitro model, the concentrations used were not safe for the ZFL lineage.

Comparative acute toxicity of glyphosate-based herbicide (GBH) to Daphnia magna, Tisbe longicornis, and Emerita analoga

The aim of this work was to know the differential composition of the dissolved fraction of a glyphosate-based herbicide (GBH), commercialized as GLIFOPAC, when reaches different aquatic environments and its ecotoxicological effects on crustaceans species living in them. Daphnia magna, Tisbe longicornis, and Emerita analoga were exposed to glyphosate herbicide called GLIFOPAC (480 g L-1 of active ingredient or a.i.) at concentrations between 0.5 and 4.8 g a.i. L-1. Acute toxicity in D. magna (48 h-LC50), E. analoga (48 h-LC50), and T. longicornis (96 h-LC50) was studied. Chromatographic analysis of the GBH composition used and water (freshwater/sea water) polluted with GLIFOPAC were evaluated. Results reported acute toxicity (48-96 h-LC50) values for D. magna, E. analoga and T. longicornis of 27.4 mg L-1, 806.4 mg L-1, and 19.4 mg L-1, respectively. Chromatographic evaluation described around 45 substances of the GLIFOPAC composition, such as from the surfactant structures (aliphatic chain with esther/ether group), metabolites (AMPA), and other substances (glucofuranose, glucopyranoside, galactopyranose). This study evidenced differences in the GLIFOPAC composition in freshwater and marine water, which may differentiate the toxic response at the crustacean-level in each aquatic environment.

Toxicity testing of pesticides in zebrafish-a systematic review on chemicals and associated toxicological endpoints

The use of zebrafish (Danio rerio) has arisen as a promising biological platform for toxicity testing of pesticides such as herbicides, insecticides, and fungicides. Therefore, it is relevant to assess the use of zebrafish in models of exposure to investigate the diversity of pesticide-associated toxicity endpoints which have been reported. Thus, this review aimed to assess the recent literature on the use of zebrafish in pesticide toxicity studies to capture data on the types of pesticide used, classes of pesticides, and zebrafish life stages associated with toxicity endpoints and phenotypic observations. A total of 352 articles published between September 2012 and May 2019 were curated. The results show an increased trend in the use of zebrafish for testing the toxicity of pesticides, with a great diversity of pesticides (203) and chemical classes (58) with different applications (41) being used. Furthermore, experimental outcomes could be clustered in 13 toxicity endpoints, mainly developmental toxicity, oxidative stress, and neurotoxicity. Organophosphorus, pyrethroid, azole, and triazine were the most studied classes of pesticides and associated with various toxicity endpoints. Studies frequently opted for early life stages (embryos and larvae). Although there is an evident lack of standardization of nomenclatures and phenotypic alterations, the information gathered here highlights associations between (classes of) pesticides and endpoints, which can be used to relate mechanisms of action specific to certain classes of chemicals.

Identification and integrated analysis of glyphosate stress-responsive microRNAs, lncRNAs, and mRNAs in rice using genome-wide high-throughput sequencing

BACKGROUND

Glyphosate has become the most widely used herbicide in the world. Therefore, the development of new varieties of glyphosate-tolerant crops is a research focus of seed companies and researchers. The glyphosate stress-responsive genes were used for the development of genetically modified crops, while only the EPSPS gene has been used currently in the study on glyphosate-tolerance in rice. Therefore, it is essential and crucial to intensify the exploration of glyphosate stress-responsive genes, to not only acquire other glyphosate stress-responsive genes with clean intellectual property rights but also obtain non-transgenic glyphosate-tolerant rice varieties. This study is expected to elucidate the responses of miRNAs, lncRNAs, and mRNAs to glyphosate applications and the potential regulatory mechanisms in response to glyphosate stress in rice.

RESULTS

Leaves of the non-transgenic glyphosate-tolerant germplasm CA21 sprayed with 2 mg·ml- 1 glyphosate (GLY) and CA21 plants with no spray (CK) were collected for high-throughput sequencing analysis. A total of 1197 DEGs, 131 DELs, and 52 DEMs were identified in the GLY samples in relation to CK samples. Genes were significantly enriched for various biological processes involved in detoxification of plant response to stress. A total of 385 known miRNAs from 59 miRNA families and 94 novel miRNAs were identified. Degradome analysis led to the identification of 32 target genes, of which, the squamosa promoter-binding-like protein 12 (SPL12) was identified as a target of osa-miR156a_L + 1. The lncRNA-miRNA-mRNA regulatory network consisted of osa-miR156a_L + 1, two transcripts of SPL12 (LOC_Os06g49010.3 and LOC_Os06g49010.5), and 13 lncRNAs (e.g., MSTRG.244.1 and MSTRG.16577.1).

CONCLUSION

Large-scale expression changes in coding and noncoding RNA were observed in rice mainly due to its response to glyphosate. SPL12, osa-miR156, and lncRNAs (e.g., MSTRG.244.1 and MSTRG.16577.1) could be a novel ceRNA mechanism in response to glyphosate in rice by regulating transcription and metal ions binding. These findings provide a theoretical basis for breeding glyphosate-tolerant rice varieties and for further research on the biogenesis of glyphosate- tolerance in rice.

Acclimation alters glyphosate temperature-dependent toxicity: Implications for risk assessment under climate change

The evaluation of temperature-dependent chemical toxicity (TDCT) is imperative for future risk assessments of pesticides under global climate change scenarios. Few TDCT studies have so far considered the ability of organisms to acclimate to altered temperatures prior to pesticide exposure, although this may change their thermal tolerance range and hence their susceptibility to pesticide stress. The objective of this study was to evaluate the effect of temperature acclimation on the sensitivity of the cladoceran Ceriodaphnia silvestrii to Glyphosate. We used the shift in sensitivity of the organisms to Glyphosate when exposed to short term temperature changes as a proxy for the effect of the developmental acclimation on sensitivity. We observed that acclimation to higher temperatures reduces the sensitivity to Glyphosate when organisms are exposed to this pesticide in lower temperatures. Therefore, acclimation to high temperatures offers some protective effect against Glyphosate toxicity. We argue that pesticide risk assessments based on tests conducted at one standard temperature should be considered with care. Realistic risk assessments considering climate change scenarios should assess the mode of which organisms are exposed to temperature, therefore taking into consideration the potential effect of temperature acclimation on the sensitivity of a species to a toxicant.

Glyphosate but not Roundup® harms earthworms (Eisenia fetida)

Glyphosate is the active ingredient in Roundup® formulations. While multiple studies have documented the toxicity, environmental persistence, and tendency to spread for glyphosate and Roundup®, few studies have compared the toxicity of glyphosate-based formulations to the toxicity of pure glyphosate for soil invertebrates, which contact both the herbicide and the formulations. Hundreds of formulations exist; their inert ingredients are confidential; and glyphosate persists in our food, water, and soil. In this experiment, we held glyphosate type and concentration constant, varying only formulation. Using Roundup Ready-to-Use III®, Roundup Super Concentrate®, and pure glyphosate, we delivered 26.3 mg glyphosate in the form of isopropylamine salt per kg of soil to compost worms (Eisenia fetida). We found that worms living in soil spiked with pure glyphosate lost 14.8-25.9% of their biomass and survived a stress test for 22.2-33.3% less time than worms living in uncontaminated soil. Worms living in soil spiked with Roundup Ready-to-Use III® and Roundup Super Concentrate® did not lose body mass and survived the stress test as well as worms living in uncontaminated soil. No contaminant affected soil microbial or fungal biomass over the 40-day period of this experiment. We suggest that the nitrates and phosphates in the formulations offset the toxic effects of glyphosate by spurring microbial growth and speeding glyphosate degradation. We also found a 26.5-41.3% reduction in fungal biomass across all treatments over the course of this experiment, suggesting that the worms consumed fungi and spores.

Ecotoxicological hazard of a mixture of glyphosate and aminomethylphosphonic acid to the mussel Mytilus galloprovincialis (Lamarck 1819)

Assessment of the effects of chemical mixtures is a very important objective of the ecotoxicological risk assessment. This study was aimed at evaluating for the first time the effects of a mixture of glyphosate and its main breakdown product aminomethylphosphonic acid (AMPA) on various biomarkers in the mussel Mytilus galloprovincialis. Mussels were exposed for 7, 14 and 21 days to either 100 µg/L of glyphosate, 100 µg/L of AMPA or a mixture of both (100 + 100 µg/L). Various haemocyte parameters, such as total haemocyte counts, haemocyte diameter and volume, haemocyte proliferation, haemolymph lactate dehydrogenase activity and haemocyte lysate acid phosphatase activities were measured. In addition, the effects of exposure on the activity of antioxidant enzymes, acetylcholinesterase and glutathione-S-transferase were evaluated in gills and digestive gland from mussels. On the whole, this study demonstrated that the variables considered in the experimental plan, namely treatment, exposure time and their interaction, affect significantly biomarker responses in M. galloprovincialis. The effects of the mixture were comparable to those of the individual compounds, whereas their synergistic effects were occasionally observed, under the experimental conditions tested at least.

Glyphosate induces toxicity and modulates calcium and NO signaling in zebrafish embryos

Glyphosate, an herbicide used worldwide, has emerged as a pollutant. However, its toxic effects are debated by regulatory authorities. Therefore, it is essential to keep the use of such chemicals under continuous observation, and their effects must be re-evaluated. We used zebrafish embryos to evaluate the toxic effects of glyphosate and its mechanisms. We found that glyphosate induced significant toxicity in a time and concentration-dependent manner. We observed an LD50 of 66.04 ± 4.6 μg/mL after 48 h of exposure. Glyphosate significantly reduced the heartbeat in a time and concentration-dependent manner indicating cardiotoxicity. Selective downregulation of Cacana1C (L-type calcium channel) and ryr2a (Ryanodine receptor) genes along with selective upregulation of hspb11 (heat shock protein) gene was observed upon exposure to glyphosate indicating alterations in the calcium signaling. A reduction in the nitric oxide (NO) generation was also observed in the zebrafish embryos upon exposure to glyphosate. Our results indicate that glyphosate induces significant toxicity including cardiotoxicity in zebrafish embryos in a time and concentration-dependent manner. Further, cardiotoxicity may be due to changes in calcium and NO signaling.

Impact of the glyphosate-based commercial herbicide, its components and its metabolite AMPA on non-target aquatic organisms

Glyphosate (GLY) is the active ingredient of several herbicide formulations widely used to control weeds in agricultural and non-agricultural areas. Due to the intensive use of GLY-based herbicides and their direct application on soils, some of their components, including the active ingredient, may reach the aquatic environment through direct run-off and leaching. The present study assessed the acute toxicity and genotoxicity of the GLY-based formulation Atanor 48 (ATN) and its major constituents GLY, surfactant polyethoxylated tallow amine (POEA), as well as the main metabolite of GLY aminomethylphosphonic acid (AMPA) on non-target aquatic organisms. The toxic effects of these chemicals were evaluated in the fish embryo acute toxicity test with zebrafish (Danio rerio), while genotoxic effects were investigated in the comet assays with cells from zebrafish larvae and rainbow trout gonad-2 (RTG-2). GLY and AMPA caused no acute toxic effect, while ATN and POEA induced significant lethal effects in zebrafish (LC50-96 h 76.50 mg/L and 5.49 mg/L, respectively). All compounds were genotoxic in comet experiments with zebrafish larvae (LOEC 1.7 mg/L for GLY, ATN, AMPA and 0.4 mg/L for POEA). Unlike in vivo, only POEA induced DNA damage in RTG-2 cells (LOEC 1.6 mg/L), suggesting that it is a direct acting genotoxic agent. In summary, these data indicate that the lethal effects on zebrafish early-life stages can be ranked in the following order from most to least toxic: surfactant POEA > formulation ATN > active ingredient GLY ≈ metabolite AMPA. Genotoxic effects were observed in both RTG-2 cells (only POEA) and zebrafish (all test compounds) with the lowest tested concentrations. Therefore, it is important to evaluate different toxicological endpoints as well as use different non-target organisms to predict the hazards of GLY-based formulations and their components and breakdown product to aquatic biota.

Dose-dependent effects of a glyphosate commercial formulation - Roundup® UltraMax - on the early zebrafish embryogenesis

The use of herbicides with glyphosate as an active ingredient, the so-called glyphosate-based herbicides (GBH), has increased dramatically in recent years currently being the most widely used in the world. Therefore, glyphosate residues have been detected in water and soils near the application sites. Recent studies indicate that GBH may cause adverse effects on vertebrates although these have been attributed to the presence of adjuvants in the commercial formulations rather than to the sole compound. Accordingly, the objective of this work was to investigate the lethal and sub-lethal developmental effects, neurotoxic potential and oxidative stress responses of zebrafish embryos to Roundup® Ultramax (RU) exposure. Embryos were exposed during 72 h to 0, 2, 5, 8.5 μg a.i. mL-1 of RU. Increased mortality was observed in embryos exposed to concentrations above 8.5 μg a.i. mL-1 as well as increased number of malformations. Decreased heart rate and hatchability were also observed. By contrast, exposure to concentrations that do not evoke teratogenic outcomes induced a dose-dependent decrease of heart rate although not inducing significant developmental changes. However, histological changes were not observed in the larvae exposed to these concentrations. Moreover, the generation of reactive oxygen species, the antioxidant enzymes activities (SOD and CAT), the GST biotransformation activity, the glutathione levels (GSH and GSSG), the oxidative damage (MDA) and the acetylcholinesterase and lactate dehydrogenase were similar among groups following exposure. Overall, available evidence suggests a dose-dependent toxicological effect of this formulation at concentrations that are not routinely detected in the environment. However, additional studies should be performed to better understand the underlying molecular mechanisms in favor of this formulation.

Developmental and epigenetic effects of Roundup and glyphosate exposure on Japanese medaka (Oryzias latipes)

Roundup and other glyphosate-based herbicides are the most commonly used herbicides in the world, yet their effects on developing fish embryos are not clearly understood. The present study, therefore, examined developmental teratogenic effects and adult-onset reproductive effects of exposure to environmentally relevant concentrations of glyphosate and Roundup in Japanese medaka fish (Oryzias latipes). Hd-rR strain medaka embryos were exposed to 0.5 mg/L glyphosate, 0.5 mg/L and 5 mg/L Roundup (glyphosate acid equivalent) for the first 15 days of their embryonic life and then allowed to sexually mature without further exposure. Whole body tissue samples were collected at 15 days post fertilization (dpf) and brain and gonad samples were collected in mature adults. Hatching success and phenotypic abnormalities were recorded up until 15 dpf. Roundup (0.5 mg/L) and glyphosate decreased cumulative hatching success, while glyphosate exposure increased developmental abnormalities in medaka fry. Expression of the maintenance DNA methyltransferase gene Dnmt1 decreased, whereas expression of methylcytosine dioxygenase genes (Tet1, Tet2 and Tet3) increased in fry at 15 dpf suggesting that epigenetic alterations increased global DNA demethylation in the developing fry. Fecundity and fertilization efficiency were not altered due to exposure. Among the reproduction-related genes in the brain, kisspeptin receptor (Gpr54-1) expression was significantly reduced in females exposed to 0.5 mg/L and 5 mg/L Roundup, and Gpr54-2 was reduced in the 0.5 mg/L Roundup treatment group. No change in expression of these genes was observed in the male brain. In the testes, expression of Fshr and Arα was significantly reduced in medaka exposed to 0.5 mg/L Roundup and glyphosate, while the expression of Dmrt1 and Dnmt1 was reduced in medaka exposed to 0.5 mg/L glyphosate. No change in expression of these genes was observed in the ovaries. The present study demonstrates that Roundup and its active ingredient glyphosate can induce developmental, reproductive, and epigenetic effects in fish; suggesting that ecological species, mainly fish, could be at risk for endocrine disruption in glyphosate and Roundup-contaminated water bodies.

Assessment of Glyphosate Induced Epigenetic Transgenerational Inheritance of Pathologies and Sperm Epimutations: Generational Toxicology

Ancestral environmental exposures to a variety of factors and toxicants have been shown to promote the epigenetic transgenerational inheritance of adult onset disease. One of the most widely used agricultural pesticides worldwide is the herbicide glyphosate (N-(phosphonomethyl)glycine), commonly known as Roundup. There are an increasing number of conflicting reports regarding the direct exposure toxicity (risk) of glyphosate, but no rigorous investigations on the generational actions. The current study using a transient exposure of gestating F0 generation female rats found negligible impacts of glyphosate on the directly exposed F0 generation, or F1 generation offspring pathology. In contrast, dramatic increases in pathologies in the F2 generation grand-offspring, and F3 transgenerational great-grand-offspring were observed. The transgenerational pathologies observed include prostate disease, obesity, kidney disease, ovarian disease, and parturition (birth) abnormalities. Epigenetic analysis of the F1, F2 and F3 generation sperm identified differential DNA methylation regions (DMRs). A number of DMR associated genes were identified and previously shown to be involved in pathologies. Therefore, we propose glyphosate can induce the transgenerational inheritance of disease and germline (e.g. sperm) epimutations. Observations suggest the generational toxicology of glyphosate needs to be considered in the disease etiology of future generations.

Glyphosate affects haemocyte parameters in the clam Ruditapes philippinarum

This study was aimed at evaluating the effects of glyphosate on haemocyte parameters of the clam Ruditapes philippinarum. Clams were exposed for 7 days to differing glyphosate concentrations (10, 100 and 1000 μg/L) and various haemocyte parameters were measured, such as total haemocyte count (THC), haemocyte diameter and volume, haemocyte proliferation, haemolymph lactate dehydrogenase activity, haemocyte lysate lysozyme and acid phosphatase activities. Glyphosate reduced significantly THC values, while increased both diameter and volume of haemocytes. Exposure to the highest herbicide concentration increased significantly haemocyte proliferation. No significant effects on haemolymph lactate dehydrogenase and haemocyte lysate lysozyme activities were observed, whereas haemocyte lysate acid phosphatase activity resulted significantly increased in clams exposed at 100 and 1000 μg/L. On the whole, this study demonstrated that glyphosate influenced significantly haemocyte parameters in R. philippinarum.

Chromosome Missegregation and Aneuploidy Induction in Human Peripheral Blood Lymphocytes In vitro by Low Concentrations of Chlorpyrifos, Imidacloprid and α-Cypermethrin

Chlorpyrifos, imidacloprid, and α-cypermethrin are some of the most widely used insecticides in contemporary agriculture. However, their low-dose, nontarget genotoxic effects have not been extensively assayed. As one of the most relevant cancer biomarkers, we aimed to assess the aneuploidy due to chromosome missegregation during mitosis. To aim it we treated human lymphocytes in vitro with three concentrations of insecticides equivalents relevant for real scenario exposure assessed by regulatory agencies. We focused on chlorpyrifos as conventional and imidacloprid and α-cypermethrin as sustainable use insecticides. Cytokinesis-blocked micronucleus assay was performed coupled with fluorescence in situ hybridization (FISH) with directly labeled pancentromeric probes for chromosomes 9, 18, X and Y. None of the insecticides induced significant secondary DNA damage in terms of micronuclei (MN), nuclear buds (NB), or nucleoplasmic bridges (NPB). However, significant disbalances in chromosomes 9, 18, X and Y, and in insecticide-treated cells has been observed. According to recent studies, these disbalances in chromosome numbers may be atributted to defect sister chromatid cohesion which contribute to the increase of chromosome missegregation but not to micronuclei incidence. We conclude that tested insecticidal active substances exert chromosome missegregation effects at low concentrations, possibly by mechanism of sister chromatid cohesion. These findings may contribute to future risk assesments and understanding of insecticide mode of action on human genome. Environ. Mol. Mutagen. 60:72-84, 2019. © 2018 Wiley Periodicals, Inc.