Short exposure to glyphosate induces locomotor, craniofacial, and bone disorders in zebrafish (Danio rerio) embryos

ADB-FUBINACA-induced developmental toxicity, neurotoxicity, and cardiotoxicity in embryonic zebrafish (Danio rerio)

As an emerging pollutant, the synthetic cannabinoid N-(1-amino-3,3-dimethyl-1-oxobutan-2-yl)-1-(4-fluorobenzyl)-1H-indazole-3-carboxamide (ADB-FUBINACA) is widely abused and frequently detected in metropolitan wastewater. However, its effect on aquatic organisms remains unexplored. In this study, embryonic and larval zebrafish were exposed to sublethal concentrations of ADB-FUBINACA to assess its toxic effects via behavioral, biochemical, and metabolomic analyses. The observed morphological defects included reduced heartbeat, shorter body length, spinal deformation, and pericardial edema. Transgenic zebrafish exhibited cardiac developmental defects and apoptosis, indicating that cardiotoxicity is associated with dysregulated gene expression. Impaired motor activity and disrupted neuronal development suggested neurotoxicity. Elevated reactive oxygen species (ROS) and malondialdehyde (MDA) levels indicate oxidative stress, whereas transcriptional changes in immune-related genes reflect a dysregulated inflammatory response. Metabolomic analyses revealed disruptions in pathways related to alanine, purine, and pyrimidine metabolism, and arginine biosynthesis, which correlated with oxidative damage, cardiotoxicity, and neurodevelopmental effects. In conclusion, ADB-FUBINACA induces developmental toxicity in zebrafish embryos via oxidative stress and metabolic disruption, highlighting the potential environmental risks posed by this emerging pollutant.

The relationship between urinary glyphosate and all-cause and specific-cause mortality: a prospective study

Glyphosate (GLY) is a well-known herbicide with significant applications in both agriculture and non-agriculture. However, GLY overuse in recent years has resulted in detection of GLY residues in many crops, endangering human health and food safety. Our aim is to investigate the relationship between urinary GLY and mortality, as well as its influencing factors. The National Health and Nutrition Examination Survey (NHANES) data from 4740 American adults were examined. Fitted smooth curves, generalized summation models, and multiple logistic regression models were used to investigate the relationship between urinary GLY and mortality. To investigate potential regulatory elements between the two effects, perform subgroup analysis. During a median follow-up of 4.03 years, there were a total of 238 all-cause deaths, 75 cardiovascular disease (CVD) deaths and 52 cancer deaths. The urinary GLY is positively correlated with all-cause mortality. Each 1 ng/ml increase in urinary GLY was associated with a 40% increased risk of all-cause mortality (Hazard ratio (HR) 1.40, 95% confidence interval (CI) 1.09-1.80), and an 50% increased risk of all-cause mortality in High group compared with Low group (HR 1.50, 95% CI 1.05-2.14). In subgroup analysis, the association between urinary GLY and all-cause mortality was significantly modified by gender (P for interaction = 0.03), and the association between urinary GLY and cancer mortality was significantly modified by hypertension (P for interaction = 0.022). Higher urinary GLY seems to be associated with more all-cause death, and gender may affect this association. Furthermore, urine GLY may have a higher effect on cancer mortality in people without hypertension.

From repellent to risk: DEET's adverse effects on hormones and bone health in kids

INTRODUCTION

Early life bone accumulation, which predicts future fragility fracture risk, is intimately associated with sex hormones. N, N-diethyl-3-methylbenzamide (DEET) is the primary and most effective active ingredient widely used globally, especially among children and adolescents. However, the effects of DEET on sex hormones and bone mass remain unclear.

OBJECTIVE

We aimed to explore the adverse effects of DEET exposure on bone mass and to elucidate the potential mediating roles of sex hormones in children and adolescents.

METHODS

This cross-sectional study analyzed 864 children and adolescents from NHANES 2013-2016. Urinary 3-diethyl-carbamoyl benzoic acid (DCBA) was employed as a biomarker for DEET exposure. The study examined the relationships between DCBA, sex hormones, and bone mass, with a particular focus on evaluating the independent and serial mediation effects of sex hormones on DEET-bone mass associations.

RESULTS

Increased DCBA was associated with decreased testosterone (TT), estrogen (E2), and free androgen index (FAI), alongside an increase in sex hormone-binding globulin (SHBG) levels, particularly pronounced among subjects < 12 years [β% (95 % CI) = -0.081 (-0.144, -0.017), -0.064 (-0.114, -0.013), -0.101 (-0.177, -0.024), and 0.020 (-0.009, 0.048), respectively] and non-overweight subjects [β% (95 % CI) = -0.160 (-0.234, -0.086), -0.103 (-0.158, -0.048), -0.195 (-0.282, -0.107), and 0.035 (0.012, 0.058), respectively]. Negative dose-response relationships between DCBA and bone mass were observed in non-overweight participants [β% (95 % CI) = -0.011 (-0.018, -0.005) and -0.027 (-0.041, -0.013) for total bone mineral density (BMD) and total bone mineral content (BMC), respectively], and in children < 12 years for total BMC [β% (95 % CI) = -0.012 (-0.024, 0.000)]. Additionally, TT, E2, and SHBG were found to significantly and independently mediate 15.41 % to 79.84 % of the relationship between DCBA and bone mass. Furthermore, serial mediation effects among sex hormones were detected between TT, E2, and SHBG.

CONCLUSIONS

DEET exerts a detrimental effect on bone health by interfering with sex hormones in children and adolescents, warranting heightened public concern.

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.

Maternal exposure to glyphosate increased the risk of adverse neurodevelopmental outcomes in rodent offspring: A systematic review

The potential neurotoxicity of environmental contaminants, such as pesticides, is implicated in the etiology of neurodevelopmental disorders, particularly given the heightened vulnerability of the developing brain. Among these contaminants, glyphosate, a widely used herbicide, has been linked to alterations in neurodevelopment, though its precise neurotoxic mechanisms are not fully elucidated. In this context, our systematic review evaluates the impact of maternal exposure to glyphosate alone (GLY) or glyphosate-based-herbicide (GBH) on neurodevelopmental and behavioral outcomes in rodent offspring. This assessment encompasses a comprehensive examination of behavioral, biochemical, morphological, and genetic alterations resulting from perinatal glyphosate exposure. The Systematic review protocol was registered in the platform Open Science Framework (OSF) following the guidelines of the Systematic Review Center for Laboratory Animal Experimentation (SYRCLE). Our analysis demonstrate that glyphosate disrupts redox signaling, metabolic pathways, and neurotransmitter systems, thereby affecting brain architecture and function across genders and developmental stages in rodents. The results of this review elucidate the extensive neurochemical and behavioral disruptions attributed to glyphosate, highlighting the critical need for advanced neurodevelopmental risk assessment methodologies. Such refined evaluations are vital to inform targeted prevention and intervention strategies in the context of environmental neurotoxicants.

Molecular mechanisms of environmental pollutant-induced cartilage damage: from developmental disorders to osteoarthritis

The objective of the present study was to review the molecular mechanisms of the adverse effects of environmental pollutants on chondrocytes and extracellular matrix (ECM). Existing data demonstrate that both heavy metals, including cadmium (Cd), lead (Pb), and arsenic (As), as well as organic pollutants, including polychlorinated dioxins and furans (PCDD/Fs) and polychlorinated biphenyls (PCB), bisphenol A, phthalates, polycyclic aromatic hydrocarbons (PAH), pesticides, and certain other organic pollutants that target cartilage ontogeny and functioning. Overall, environmental pollutants reduce chondrocyte viability through the induction apoptosis, senescence, and inflammatory response, resulting in cell death and impaired ECM production. The effects of organic pollutants on chondrocyte development and viability were shown to be mediated by binding to the aryl hydrocarbon receptor (AhR) signaling and modulation of non-coding RNA expression. Adverse effects of pollutant exposures were observed in articular and growth plate chondrocytes. These mechanisms also damage chondrocyte precursors and subsequently hinder cartilage development. In addition, pollutant exposure was shown to impair chondrogenesis by inhibiting the expression of Sox9 and other regulators. Along with altered Runx2 signaling, these effects also contribute to impaired chondrocyte hypertrophy and chondrocyte-to-osteoblast trans-differentiation, resulting in altered endochondral ossification. Several organic pollutants including PCDD/Fs, PCBs and PAHs, were shown to induce transgenerational adverse effects on cartilage development and the resulting skeletal deformities. Despite of epidemiological evidence linking human environmental pollutant exposure to osteoarthritis or other cartilage pathologies, the data on the molecular mechanisms of adverse effects of environmental pollutant exposure on cartilage tissue were obtained from studies in laboratory rodents, fish, or cell cultures and should be carefully extrapolated to humans, although they clearly demonstrate that cartilage should be considered a putative target for environmental pollutant toxicity.

Exploring estrogen antagonism using CRISPR/Cas9 to generate specific mutants for each of the receptors

Endocrine disruptors are chemicals that have been in the spotlight for some time now. Their modulating action on endocrine signaling pathways made them a particularly interesting topic of research within the field of ecotoxicology. Traditionally, endocrine disrupting properties are studied using exposure to suspected chemicals. In recent years, a major breakthrough in biology has been the advent of targeted gene editing tools to directly assess the function of specific genes. Among these, the CRISPR/Cas9 method has accelerated progress across many disciplines in biology. This versatile tool allows to address antagonism differently, by directly inactivating the receptors targeted by endocrine disruptors. Here, we used the CRISPR/Cas9 method to knock out the different estrogen receptors in zebrafish and we assessed the potential effects this generates during development. We used a panel of biological tests generally used in zebrafish larvae to investigate exposure to compounds deemed as endocrine disrupting chemicals. We demonstrate that the absence of individual functional estrogen receptors (Esr1, Esr2b, or Gper1) does affect behavior, heart rate and overall development. Each mutant line was viable and could be grown to adulthood, the larvae tended to be morphologically grossly normal. A substantial fraction (70%) of the esr1 mutants presented severe craniofacial deformations, while the remaining 30% of esr1 mutants also had changes in behavior. esr2b mutants had significantly increased heart rate and significant impacts on craniofacial morphometrics. Finally, mutation of gper1 affected behavior, decreased standard length, and decreased bone mineralization as assessed in the opercle. Although the exact molecular mechanisms underlying these effects will require further investigations in the future, we added a new concept and new tools to explore and better understand the actions of the large group of endocrine disrupting chemicals found in our environment.

Decrypting the skeletal toxicity of vertebrates caused by environmental pollutants from an evolutionary perspective: From fish to mammals

The rapid development of modern society has led to an increasing severity in the generation of new pollutants and the significant emission of old pollutants, exerting considerable pressure on the ecological environment and posing a serious threat to both biological survival and human health. The skeletal system, as a vital supportive structure and functional unit in organisms, is pivotal in maintaining body shape, safeguarding internal organs, storing minerals, and facilitating blood cell production. Although previous studies have uncovered the toxic effects of pollutants on vertebrate skeletal systems, there is a lack of comprehensive literature reviews in this field. Hence, this paper systematically summarizes the toxic effects and mechanisms of environmental pollutants on the skeletons of vertebrates based on the evolutionary context from fish to mammals. Our findings reveal that current research mainly focuses on fish and mammals, and the identified impact mechanisms mainly involve the regulation of bone signaling pathways, oxidative stress response, endocrine system disorders, and immune system dysfunction. This study aims to provide a comprehensive and systematic understanding of research on skeletal toxicity, while also promoting further research and development in related fields.

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.

Maternal exposure of mice to glyphosate induces depression- and anxiety-like behavior in the offspring via alterations of the gut-brain axis

The past decade has been characterized by increased awareness and de-stigmatization of mental health issues, in particular the most common neuropsychiatric disorders depression and anxiety. Further, with growing understanding of neurodevelopmental disorders such as attention deficit and hyperactivity disorder and autism spectrum disorder, the number of diagnosed patients has increased. The pathogenesis of these behavioral disorders is multifactorial and early-life exposure to environmental chemicals has been proposed to be a relevant risk factor that might mediate these effects by disturbances on the gut-brain-axis. However, for glyphosate, the most widely used pesticide worldwide, there are only limited and inconsistent findings that link chronic low-dose exposure in particular during early life to neurobehavioral disorders. Here, we explored the impact of maternal oral glyphosate exposure (0.5 and 50 mg/kg body weight/day) during pregnancy and the lactational period on offspring's behavior, brain gene expression and gut microbiota using a cross-generational mouse model. Behavioral analyses revealed a depression- and anxiety-like behavior as well as social deficits most notably in adult female offspring of glyphosate-exposed dams. Furthermore, the expression of tryptophan hydroxylase 2, an enzyme discussed to be linked to behavioral problems, was reduced in the hippocampus of female offspring and correlated to a glyphosate-induced DNA hypermethylation of the gene. Moreover, maternal glyphosate exposure significantly altered the gut microbiota in the female offspring including a decreased abundance of Akkermansia and increased abundance of Alistipes and Blautia, bacteria involved in tryptophan metabolism and associated with depression- and anxiety-like disorders. Our results suggest that glyphosate might influence the gut-brain axis crosstalk following in-utero and lactational exposure. This study underlines the importance of understanding the impact of exposure to pesticides on the gut-brain axis and further emphasizes the need for microbiome analyses to be compulsorily included in health risk assessments of pesticides.

Developmental toxicity and estrogenicity of glyphosate in zebrafish in vivo and in silico studies

As the most heavily used herbicide globally, glyphosate (GLY) has been detected in a variety of environments and has raised concerns about its ecological and health effects. There is debate as to whether GLY may disrupt the endocrine system. Here, we investigated the developmental toxicity of GLY in zebrafish based on deep learning-enabled morphometric analysis (DLMA). In addition, the estrogenic activity of GLY was assessed by endocrine disruption prediction, docking study and in vivo experiments. Results showed that exposure to environmental concentrations of GLY negatively impacted zebrafish development, causing yolk edema and pericardial edema. Endocrine disruption prediction suggested that GLY may target estrogen receptors (ER). Molecular docking analysis revealed binding of GLY to three zebrafish ER. In vivo zebrafish experiment, GLY enhanced the protein levels of ERα and the mRNA levels of cyp19a, HSD17b1, vtg1, vtg2, esr1, esr2a and esr2b. These results suggest that GLY may act as an endocrine disruptor by targeting ER, which warrants further attention for its potential toxicity to aquatic animals.

GLYPHOSATE IMPACT on human health and the environment: Sustainable alternatives to replace it in Mexico

Glyphosate is a broad-spectrum, non-selective herbicide used to control weeds and protect agricultural crops, and it is classified as potentially carcinogenic by the International Agency for Research on Cancer. In Mexico, the use of pesticides is a common practice, including glyphosate. However, on December 31st, 2020, the Mexican government decreed the prohibition of this herbicide as of January 2024. In this review, we investigate the association between glyphosate and cancer risk and found that most of the studies focused using animals showing negative effects such as genotoxicity, cytotoxicity and neurotoxicity, some studies used cancer cell lines showing proliferative effects due to glyphosate exposure. To our knowledge, in Mexico, there are no scientific reports on the association of glyphosate with any type of cancer. In addition, we reviewed the toxicological effects of the herbicide glyphosate, and the specific case of the current situation of the use and environmental damage of this herbicide in Mexico. We found that few studies have been published on glyphosate, and that the largest number of publications are from the International Agency for Research on Cancer classification to date. Additionally, we provide data on glyphosate stimulation at low doses as a biostimulant in crops and analytical monitoring techniques for the detection of glyphosates in different matrices. Finally, we have tried to summarize the actions of the Mexican government to seek sustainable alternatives and replace the use of glyphosate, to obtain food free of this herbicide and take care of the health of the population and the environment.

Glyphosate induces autophagy in hepatic L8824 cell line through NO-mediated activation of RAS/RAF/MEK/ERK signaling pathway and energy metabolism disorders

Glyphosate is an herbicide commonly used worldwide, and its substantial use causes widespread pollution with runoff. However, research on glyphosate toxicity has mostly remained at the embryonic level and existing studies are limited. In the present study, we investigated whether glyphosate can induce autophagy in hepatic L8824 cells by regulating energy metabolism and rat sarcoma (RAS)/rapidly accelerated fibrosarcoma (RAF)/mitogen-activated extracellular signal-regulated kinase (MEK)/extracellular regulated protein kinases (ERK) signaling by activating nitric oxide (NO). First, we selected 0, 50, 200, and 500 μg/mL as the challenge doses, according to the inhibitory concentration of 50% (IC50) of glyphosate. The results showed that glyphosate exposure increased the enzyme activity of inducible nitric oxide synthase (iNOS), which in turn increased the NO content. The activity and expression of enzymes related to energy metabolism, such as hexokinase (HK)1, HK2, phosphofructokinase (PFK), phosphokinase (PK), succinate dehydrogenase (SDH), and nicotinamide adenine dinucleotide with hydrogen (NADH), were inhibited, and the RAS/RAF/MEK/ERK signaling pathway was activated. This led to the negative expression of mammalian target of rapamycin (mTOR) and P62 in hepatic L8824 cells and the activation of the autophagy marker genes microtubule-associated proteins light chain 3 (LC3) and Beclin1 to induce autophagy. The above results were dependent on glyphosate concentration. To verify whether autophagy can be excited by the RAS/RAF/MEK/ERK signaling pathway, we treated L8824 cells with the ERK inhibitor U0126 and found that the autophagy gene LC3 was reduced due to the inhibition of ERK, thus demonstrating the reliability of the results. In conclusion, our results demonstrate that glyphosate can induce autophagy in hepatic L8824 cells by activating NO, thus regulating energy metabolism and the RAS/RAF/MEK/ERK signaling pathway.

Molecular, morphological and behavioral alterations of zebrafish (Danio rerio) embryos/larvae after clorprenaline hydrochloride exposure

Chlorprenaline hydrochloride (CLOR) is a typical representative of β-adrenergic agonists that may be used illegally as a livestock feed additive and may have adverse impacts on the environment. In the present study, zebrafish embryos were exposed to CLOR to investigate its developmental toxicity and neurotoxicity. The results demonstrated that CLOR exposure led to adverse effects on developing zebrafish, such as morphological changes, a high heart rate, and increased body length, resulting in developmental toxicity. Moreover, the up-regulation of activities of superoxide dismutase (SOD) and catalase (CAT) and the enhancement of malondialdehyde (MDA) content illustrated that CLOR exposure activated oxidative stress in exposed zebrafish embryos. Meanwhile, CLOR exposure also caused alterations in locomotive behavior in zebrafish embryos, including an increase in acetylcholinesterase (AChE) activity. Quantitative polymerase chain reaction (QPCR) results showed that the transcription of genes related to the central nervous system (CNS) development, namely, mbp, syn2a, α1-tubulin, gap43, shha, and elavl3, indicated that CLOR exposure could lead to neurotoxicity in zebrafish embryos. These results showed that CLOR exposure could cause developmental neurotoxicity in the early stages of zebrafish development and that CLOR might induce neurotoxicity by altering the expression of neuro-developmental genes, elevating AChE activity, and activating oxidative stress.

Sublethal effects of the herbicides atrazine and glyphosate at environmentally relevant concentrations on South American catfish (Rhamdia quelen) embryos

The objective of this work was to evaluate the effects following exposure (96 h) of South American catfish (R. quelen) embryos to active ingredients and commercial formulations from atrazine and glyphosate, isolated and in mixtures, at environmentally relevant concentrations. While the survival rates were not affected, sublethal effects were evidenced after exposure. The most frequent deformities were fin damage and axial and thoracic damage. The mixture of active ingredients caused an increase in SOD and GST, differing from the treatment with the mixture of commercial formulations. The activity of AChE was significantly reduced following the treatment with the active ingredient atrazine and in the mixture of active ingredients. In general, herbicide mixtures were responsible for causing more toxic effects to R. quelen embryos. Therefore, these responses showed to be suitable biomarkers of herbicides' exposure, in addition to generating more environmentally relevant baseline data for re-stablishing safety levels of these substances in aquatic bodies.

2,4-di-tert-butylphenol exposure impairs osteogenic differentiation

2,4-di-tert-butylphenol (2,4-DTBP) is a synthetic antioxidant used in polyethylene crosspolymer (PEX) water distribution pipes and food-related plastics. 2,4-DTBP can leach from plastic materials and has been found in breast milk, cord blood, and placental tissue, giving rise to the concern that this compound may interfere with fetal development. The objective of this study is to assess the impacts of 2,4-DTBP on cellular differentiation. Human induced pluripotent stem (HiPS) cells were differentiated into osteoblasts or myoblasts over 40 days, and analyzed for markers of somite, dermomyotome, sclerotome, myoblast, and osteoblast development. When cultured as stem cells, 2,4-DTBP did not alter cell viability and expression of markers (NANOG, OCT4). However, upon differentiation into somite-like cells, 2,4-DTBP had reduced levels of MEOX1 and TBX6 transcripts, while NANOG and OCT4 were in turn upregulated in a dose-dependent manner. At the sclerotome-like stage, PAX9 mRNA decreased by 2-fold in the 0.5 μM and 1.0 μM 2,4-DTBP exposure groups. After 40 days of differentiation into an osteoblast-like lineage, exposure to 2,4-DTBP significantly reduced expression of the osteogenesis transcripts RUNX2 and OSX in a dose-dependent manner. Further, Alizarin Red staining of calcium deposits was decreased in the 0.5 μM and 1.0 μM treatment groups. In contrast, myogenesis was not affected by 2,4-DTBP exposure. Interestingly, KEAP1 expression was significantly increased in the sclerotomal-like cells, but decreased in the dermomytomal-like cells, which may suggest a mechanism of action. Overall, this study shows that 2,4-DTBP can delay key processes during sclerotome and osteoblast development, leading to a potential for bone developmental issues in exposed individuals.

Glyphosate-based herbicide (GBH) causes damage in embryo-larval stages of zebrafish (Danio rerio)

Glyphosate-Based Herbicides (GBH) show risks to the environment and also to aquatic organisms, such as fish. The present work aimed to evaluate the effects of GBH and Pure Glyphosate (PG) exposure on Danio rerio embryos at drinking water concentrations. Zebrafish embryos were exposed to 250, 500, and 1000 μg L^-1 of Roundup Original DI® and pure glyphosate for 96 h. Glyphosate concentration in water, parameters physicochemical water, survival, hatching rate, heart rate, malformations, behavior, and biomarkers were evaluated. We verified that at 6 h post-fertilization (hpf), animals exposed to GBH 500 showed decreased survival as compared to the control. The hatching rate increased in all groups exposed to GBH at 48 hpf as compared to the control group. The embryos exposed did not present changes in the spontaneous movement and touch response. Exposed groups to GBH demonstrated a higher number of malformations in fish embryos as compared to the control. Most malformations were: pericardial edema, yolk sac edema, body malformations, and curvature of the spine. In heart rate, bradycardia occurred in groups exposed, as predicted due to cardiac abnormalities. As biochemical endpoints, we observed a decrease in Glutathione S-transferase (GBH 250, GBH 500 and PG 250) and Acetylcholinesterase (GBH 250 and PG 250) activity. No differences were found between the groups in the concentration of protein, Total Antioxidant Capacity Against Peroxyl Radicals, Lipid peroxidation, Reactive Oxygen Species, Non-protein thiols, and Catalase. In conclusion, the damage in all evaluated stages of development was aggravated by survival and malformations. Therefore, the large-scale use of GBHs, coupled with the permissiveness of its presence could be the cause damage to the aquatic environment affecting the embryonic development of non-target organisms.

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.

Chronic dietary exposure to a glyphosate-based herbicide results in reversible increase early embryo mortality in chicken

Glyphosate (Gly) is the active molecule of non-selective herbicides used in conventional agriculture. Some evidence shows that exposure to Glyphosate-Based Herbicides (GBH) can affect both male and female fertility in animal models. However, few data exist on birds that can be easily exposed through their cereal-based diet. To our knowledge, there are no current studies on the effects of chronic dietary exposure to GBH and the potential reversibility on the fertility and embryo development in chickens. In our protocol, hens (32 weeks-old) were exposed to GBH (47 mg kg-1/day-1 glyphosate equivalent corresponding to half of the No-Observed-Adverse-Effect-Level (NOAEL) as defined by European Food Safety Authority in birds, GBH group (GBH), n = 75) or not (Control group (CT), n = 75) for 6 weeks. Then, both CT and GBH groups were fed for 5 more weeks without GBH exposure. During these two periods, we investigated the consequences on the egg performance and quality, fertilization rate, embryo development, and viability of offspring. Despite the accumulation of Gly and its metabolite aminomethylphosphonic acid (AMPA) in the hen blood plasma, the body weight and laying rate were similar in GBH and CT animals. We observed from the 4th day of exposure an accumulation of Gly (but not AMPA) only in the yolk of the eggs produced by the exposed hens. After artificial insemination of the hens followed by eggs incubation, we showed a strong significant early embryonic mortality level in GBH compared to CT animals (78 ± 2 % vs 2.5 ± 0.3 %, p < 0.0001) with embryo death mainly occurring on the third day of incubation. By using computed tomography (CT) and magnetic resonance imaging (MRI) tools, we noted a significant delay in the embryo development of GBH survivors at 15 days with a reduction by half of the embryo volume and some disturbances in the calculated volumes of the embryonic annexes. At 20 days of incubation, we showed a reduction in the length of the tibia and in the volume of the soft tissues whereas the skeleton volume was increased in GBH chicks. The vast majority of these phenotypes disappeared two weeks after an arrest of the GBH maternal dietary exposure. Taken together, the dietary chronic exposure of broiler hens to GBH at a Gly equivalent concentration lower than NOAEL induces an accumulation of Gly in the egg yolk resulting in severe early embryonic mortality and a delayed embryonic development in survivors that were abolished two weeks after the end of GBH exposure.

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.