An approach to clarify the effect mechanism of glyphosate on body malformations during embryonic development of zebrafish (Daino rerio)

Environmental safety and mode of action of a novel curcumin-based photolarvicide

Aedes aegypti is the vector of important diseases like dengue, zika, chikungunya, and yellow fever. Vector control is pivotal in combating the spread of these mosquito-borne illnesses. Photoactivable larvicide curcumin obtained from Curcuma longa Linnaeus has shown high potential for Ae. aegypti larvae control. However, the toxicity of this photosensitizer (PS) might jeopardize non-target aquatic organisms. The aim of this study was to evaluate the toxicity of this PS to Daphnia magna and Danio rerio, besides assessing its mode of action through larvae biochemical and histological studies. Three PS formulations were tested: PS in ethanol+DMSO, PS in sucrose, and PS in D-mannitol. The LC₅₀ of PS in ethanol+DMSO to D. rerio was 5.9 mg L^-1, while in D. magna the solvents were extremely toxic, and LC₅₀ was not estimated. The PS formulations in sugars were not toxic to neither of the organisms. Reactive oxygen species (ROS) were generated in D. magna exposed to 50 mg L^-1 of PS in D-mannitol, and D. rerio did not elicit this kind of response. D. magna feeding rates were not affected by the PS in D-mannitol. Concerning Ae. aegypti larvae, there were changes in reduced glutathione and protein levels, while catalase activity remained stable after exposure to PS in D-mannitol and sunlight. Histological changes were observed in larvae exposed to PS in sucrose and D-mannitol, most of them irreversible and deleterious. Our results show the feasibility of this photolarvicide use in Ae. aegypti larvae control and its safety to non-target organisms. These data are crucial to this original vector control approach implementation in public health policies.

Carbonic Anhydrase Sensitivity to Pesticides: Perspectives for Biomarker Development

Carbonic anhydrase (CA) is a widespread metalloenzyme playing a pivotal role in several physiological processes. Many studies have demonstrated the in vitro and in vivo sensitivity of CA to the exposure to several classes of pesticides in both humans and wildlife. This review aims to analyze and to discuss the literature available in this field, providing a comprehensive view useful to foresee perspectives for the development of novel CA-based pesticide biomarkers. The analysis of the available data highlighted the ability of several pesticide molecules to interact directly with the enzyme in humans and wildlife and to inhibit CA activity in vitro and in vivo, with possible alterations of key physiological functions. The analysis disclosed key areas of further research and, at the same time, identified some perspectives for the development of novel CA-based sensitive biomarkers to pesticide exposure, suitable to be used in several fields from human biomonitoring in occupational and environmental medicine to environmental monitoring on non-target species.

Nodularin induced oxidative stress contributes to developmental toxicity in zebrafish embryos

Nodularin (NOD) is a kind of cyanobacterial toxins. It is of concern due to elicit severe genotoxicity in humans and animals. The comprehensive evaluation of NOD-induced adverse effects in living organisms is urgently needed. This study is aimed to report the developmental toxicity and molecular mechanism using zebrafish embryos exposed to NOD. The embryonic toxicity induced by NOD is demonstrated by inhibition of embryo hatching, increase in mortality rate, abnormal heart rate, embryonic malformation as well as defects in angiogenesis and common cardinal vein remodeling. NOD triggered a decreased rate of angiogenesis through inhibiting endothelial cells migration. NOD induced embryonic cell apoptosis and DNA damage, which can be alleviated by antioxidant N-acetyl-L-cysteine. NOD significantly caused oxidative damage as indicated by changes in reactive oxygen species, superoxide dismutase, catalase, glutathione and malondialdehyde. NOD also altered the expression of vascular development-genes (DLL4, CDH5, VEGFA, VEGFC) and apoptosis-related genes (BAX, BCL-2, P53, CASPASE 3). Taken together, NOD induced adverse effect on zebrafish embryos development, which may be associated with oxidative stress and apoptosis through the activation of P53-BAX/BCL-2-CASPASE 3-mediated pathway.

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.

Cytotoxic evaluation of glyphosate, using Allium cepa L. as bioindicator

Glyphosate is a chemical compound used mainly as a broad spectrum herbicide, it is recognized for its proven effectiveness and easy handling. It represents more than 60% of the world market of non-selective herbicides and is used in both agricultural fields and family gardens. The present study was designed to test the cytogenotoxic potential of glyphosate using the Allium cepa test as toxicity bioindicator. Consequently, bulbs of A. cepa were exposed to different concentrations of glyphosate (5, 10, 15, 25 and 30 mgL-1) and a control (deionized water), for 72 h; root development was also studied in this period of time. The cytogenotoxic potential of glyphosate was determined by calculating the mitotic index (MI), cellular anomalies (CA) and registering the roots longitudinal growth at 24, 48 and 72 h. Regarding root development, a greater growth was observed in the control treatment in the three measurement times. The mitotic phases analysis, determined that the higher the concentration, the lower the mitotic index, in addition the inhibition of the telophase Mitotic Index (TMI) was observed in any of the concentrations. The results indicate that the exposure to glyphosate of A. cepa meristematic cells induces diverse types of chromosomal anomalies, such as micronuclei (MN), chromosome breaking (CB), nuclear notch (Nn), among others. Therefore, in demonstrates that glyphosate has a highly cytogenotoxic effect for any of the concentrations used.

The effects of n-butanol on oxidative stress and apoptosis in zebra fish (Danio rerio) larvae

In recent years, n-butanol has growing use in many areas, including the food industry. In this study, acute toxic effects of n-butanol to zebrafish (Danio rerio) larvae by applying different concentrations (10, 50, 250, 500, 750, 1000 and 1250 mg/L) to embryos were evaluated. For this purpose the data of oxidative stress, antioxidant - acetyl cholinesterase enzyme activities, malondialdehyde level and apoptosis were taken into consideration. At the end of the 96 h, antioxidant (Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx)) and acetylcholinesterase (AChE) enzyme activities were decreased, however lipid peroxidation level, apoptotic cells, and reactive oxygen species increased (p < .05). As a result, it has been observed that high concentrations of n-butanol with its amphiphilic structure causes quite intense toxic effects in zebrafish embryos.

Polystyrene nanoplastics (20 nm) are able to bioaccumulate and cause oxidative DNA damages in the brain tissue of zebrafish embryo (Danio rerio)

Nano-sized plastic particles formed from both daily use plastics and its debris have become a potential health and environmental problem due to features such as transportation through food webs and maternal transfer. Although many studies on the toxicity of plastics exist more detailed and molecular studies are needed to evaluate and review the effects of plastics especially in nano-size range. For this purpose, we have microinjected polystyrene nanoplastics (PNP) (20 nm) to the zebrafish embryo, which is one of the best model organisms for developmental toxicity studies, to simulate intake with food or maternal. Survival, hatching and malformations evaluated during the experimental period (120 h). Moreover, we have aimed to put forth the presence of reactive oxygen species (ROS) and apoptosis signalling accumulation in the body in addition to bioaccumulation of PNP and immunochemical toxicity (8-OHdG) on the brain of zebrafish larvae at the 120th hour. According to results, it has been demonstrated that 20 nm diameter PNP can reach the brain and bioaccumulate there, moreover lead to oxidative DNA damage in the brain regions where it bioaccumulates. Here we have also imaged the PNP from a vertebrate brain via transmission electron microscopy (TEM) for the first time. As a result of these, it has been detected increasing mortality and prevailing abnormalities in addition to excessive ROS and apoptosis in especially the brain. As a conclusion, obtained data have suggested that precautions, on the use and contamination of the plastic product, to be taken during both pregnancy and baby care/feeding are important for the health of the baby in future.

Biochemical and molecular impacts of glyphosate-based herbicide on the gills of common carp

Glyphosate (GLY)-based herbicide, one of the most widely used herbicides, might cause a series of environmental problems and pose a toxicological risk to aquatic organisms. However, data on the potential hazard and toxicity mechanism of GLY to fish gills are relatively scarce. In this study, a subacute toxicity test of common carp (Cyprinus carpio L.) treated with commercial GLY at 52.08 and 104.15 mg L-1 for 7 d was conducted. The results revealed that GLY exposure significantly inhibited Na+/K+-ATPase and increased AST and ALT activities in the fish gills. The biochemical assays results revealed that GLY treatment remarkably altered the transcriptional levels of HSP70 and HSP90; inhibited the activities of SOD, CAT, GPx, GR, and T-AOC; reduced the contents of GSH, but remarkably promoted MDA and PC contents, suggesting that GLY exposure induced oxidative stress and lipids and proteins damage in the carp gills. Further research revealed that GLY exposure also promoted expression of NF-κB, iNOS, IL-1β, IL-6, IL-8, and TNF-α; altered the levels of IL-10 and TGF-β, indicating that GLY exposure induced inflammatory response in the fish gills. Additionally, we found that GLY exposure activated apaf-1 and bax and inhibited bcl-2, induced caspase-9 and caspase-3 expression and caused remarkable histological damage in the fish gills. These results may further enriches the toxicity mechanistic theory of GLY to fish gills, which may be useful for the risk assessment of GLY and aquatic organism protection.

The effects of Roundup® in embryo development and energy metabolism of the zebrafish (Danio rerio)

Roundup® is currently the most widely used and sold agricultural pesticide in the world. The objective of this work was to investigate the effects of Roundup® on energy metabolism during zebrafish (Danio rerio) embryogenesis. The embryo toxicity test was performed for 96 h post-fertilisation and the sublethal concentration of Roundup® was defined as 58.3 mg/L, which resulted in failure to inflate the swim bladder. Biochemical assays were performed with viable embryos following glyphosate exposure, and no significant effects on protein, glucose, glycogen, triglyceride levels or the enzymatic activities of alanine aminotransferase and aspartate aminotransferase were observed. However, the activity of hexokinase was significantly altered following exposure to 11.7 mg/L Roundup®. Through molecular docking we have shown for the first time that the interactions of glucokinase and hexokinases 1 and 2 with glyphosate showed significant interactions in the active sites, corroborating the biochemical results of hexokinase activity in zebrafish exposed to the chemical. From the results of molecular docking interactions carried out on the Zfishglucok, ZfishHK1 and ZfishHK2 models with the glyphosate linker, it can be concluded that there are significant interactions between glyphosate and active sites of glucokinase and hexokinase 1 and 2 proteins. The present work suggests that Roundup® can induce problems in fish embryogenesis relating to the incapacity of swim bladder to inflate. This represents the first study demonstrating the interaction of glyphosate with hexokinase and its isoforms.

How glyphosate and its associated acidity affect early development in zebrafish (Danio rerio)

BACKGROUND

Glyphosate is among the most extensively used pesticides worldwide. Following the ongoing highly controversial debate on this compound, its potential impact on non-target organisms is a fundamental scientific issue. In its pure compound form, glyphosate is known for its acidic properties.

METHODS

We exposed zebrafish (Danio rerio) embryos to concentrations between 10 μM and 10 mM glyphosate in an unbuffered aqueous medium, as well as at pH 7, for 96 hours post fertilization (hpf). Furthermore, we investigated the effects of aqueous media in the range of pH 3 to 8, in comparison with 1 mM glyphosate treatment at the respective pH levels. Additionally, we exposed zebrafish to 7-deoxy-sedoheptulose (7dSh), another substance that interferes with the shikimate pathway by a mechanism analogous to that of glyphosate, at a concentration of one mM. The observed endpoints included mortality, the hatching rate, developmental delays at 24 hpf, the heart rate at 48 hpf and the malformation rate at 96 hpf. LC10/50, EC10 and, if reasonable, EC50 values were determined for unbuffered glyphosate.

RESULTS

The results revealed high mortalities in all treatments associated with low pH, including high concentrations of unbuffered glyphosate (>500 μM), low pH controls and glyphosate treatments with pH < 3.4. Sublethal endpoints like developmental delays and malformations occurred mainly at higher concentrations of unbuffered glyphosate. In contrast, effects on the hatching rate became particularly prominent in treatments at pH 7, showing that glyphosate significantly accelerates hatching compared with the control and 7dSh, even at the lowest tested concentration. Glyphosate also affected the heart rate, resulting in alterations both at pH 7 and, even more pronounced, in the unbuffered system. In higher concentrations, glyphosate tended to accelerate the heart rate in zebrafish embryos, again, when not masked by the decelerating influence of its low pH. At pH > 4, no mortality occurred, neither in the control nor in glyphosate treatments. At 1 mM, 7dSh did not induce any mortality, developmental delays or malformations; only slightly accelerated hatching and a decelerated heart rate were observed. Our results demonstrate that lethal impacts in zebrafish embryos can be attributed mainly to low pH, but we could also show a pH-independent effect of glyphosate on the development of zebrafish embryos on a sublethal level.

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.

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.

Zebrafish as a Model for Toxicological Perturbation of Yolk and Nutrition in the Early Embryo

PURPOSE OF REVIEW

Developmental toxicity assessments often focus on structural outcomes and overlook subtle metabolic differences which occur during the early embryonic period. Deviant embryonic nutrition can result in later-life disease, including diabetes, obesity, and cardiovascular disease. Prior to placenta-mediated nutrient exchange, the human embryo requires maternally supplied nutritional substrates for growth, called yolk. Here, we compare the biology of the human and zebrafish yolk and review examples of toxicant-mediated perturbation of yolk defects, composition, and utilization.

RECENT FINDINGS

Zebrafish embryos, like human embryos, have a protruding yolk sac that serves as a nutritional cache. Aberrant yolk morphology is a common qualitative finding in fish embryotoxicity studies, but quantitative assessment and characterization provides an opportunity to uncover mechanistic targets of toxicant effects on embryonic nutrition. The zebrafish and the study of its yolk sac is an excellent model for uncovering toxicant disruptions to early embryonic nutrition and has potential to discover mechanistic insights into the developmental origins of health and disease.

Disruption of oocyte maturation by selected environmental chemicals in zebrafish

Oocyte maturation can be a target of endocrine disruption by environmental chemicals capable of acting as hormone mimics, receptor blockers, and/or enzyme inhibitors. Six environmental chemicals (genistein, endosulfan, malathion, iprodione, carbaryl, and glyphosate) were selected to determine their ability to interfere with oocyte maturation in zebrafish. The translucent oocytes undergoing germinal vesicle (nucleus) breakdown (GVBD) were counted and expressed as a ratio of oocytes undergoing GVBD and total oocytes exposed. The GVBD increased significantly in oocytes exposed to 10 IU/ml to 100 IU/ml human chorionic gonadotropin (hCG). The lowest effective concentration of genistein that inhibited hCG-induced GVBD was 30 μM, while endosulfan inhibited it at 0.03 μM concentration. In addition, malathion inhibited hCG-induced GVBD at the lowest concentration of 60 μM. These inhibitory effects were likely due to the chemicals acting as estrogen mimics, induction of estrogen receptors, or increase in aromatase activity resulting in enhanced estrogen action. Fungicide iprodione, possibly acting as a progestin mimic, promoted hCG-induced GVBD at the lowest concentration of 20 μM, while the weed killer glyphosate inhibited hCG-induced GVBD starting at the 50 μM concentration. These results demonstrate the feasibility of using fully grown zebrafish oocytes arrested at the prophase I stage in an in vitro incubation system to evaluate the effects of a variety of environmental chemicals on oocyte maturation.

Maternal residential exposure to specific agricultural pesticide active ingredients and birth defects in a 2003-2005 North Carolina birth cohort

BACKGROUND

Previously we observed elevated odds ratios (ORs) for total pesticide exposure and 10 birth defects: three congenital heart defects and structural defects affecting the gastrointestinal, genitourinary and musculoskeletal systems. This analysis examines association of those defects with exposure to seven commonly applied pesticide active ingredients.

METHODS

Cases were live-born singleton infants from the North Carolina Birth Defects Monitoring Program linked to birth records for 2003-2005; noncases served as controls (total n = 304,906). Pesticide active ingredient exposure was assigned using a previously constructed metric based on crops within 500 m of residence, dates of pregnancy, and likely chemical application dates for each pesticide-crop combination. ORs (95% CI) were estimated with logistic regression for categories of exposure compared to unexposed. Models were adjusted for maternal race/ethnicity, age at delivery, education, marital status, and smoking status.

RESULTS

Associations varied by birth defect and pesticide combinations. For example, hypospadias was positively associated with exposures to 2,4-D (OR_{50th to <90th percentile} : 1.39 [1.18, 1.64]), mepiquat (OR_{50th to <90th percentile} : 1.10 [0.90, 1.34]), paraquat (OR_{50th to <90th} : 1.14 [0.93, 1.39]), and pendimethalin (OR_{50th to <90th} : 1.21 [1.01, 1.44]), but not S-metolachlor (OR_{50th to <90th} : 1.00 [0.81, 1.22]). Whereas atrial septal defects were positively associated with higher levels of exposure to glyphosate, cyhalothrin, S-metolachlor, mepiquat, and pendimethalin (ORs ranged from 1.22 to 1.35 for 50th to <90th exposures, and 1.72 to 2.09 for >90th exposures); associations with paraquat were null or inconsistent (OR 50th to <90th: 1.05 (0.87, 1.27).

CONCLUSION

Our results suggest differing patterns of association for birth defects with residential exposure to seven pesticide active ingredients in North Carolina.

Low-concentration exposure to glyphosate-based herbicide modulates the complexes of the mitochondrial respiratory chain and induces mitochondrial hyperpolarization in the Danio rerio brain

Glyphosate (N-phosphonomethyl-glycine) (GLY) is the active ingredient of the most used herbicides in the world. GLY is applied in formulated products known as glyphosate-based herbicides (GBH), which could induce effects that are not predicted by toxicity assays with pure GLY. This herbicide is classified as organophosphorus compound, which is known to induce neurotoxic effects. Although this compound is classified as non-neurotoxic by regulatory agencies, acute exposure to GBH causes neurological symptoms in humans. However, there is no consensus in relation to neurotoxic effects of GBH. Thus, the aim of this study was to investigate the neurotoxic effects of the GBH in the zebrafish Danio rerio, focusing on acute toxicity, the activity and transcript levels of mitochondrial respiratory chain complexes, mitochondrial membrane potential, reactive species (RS) formation, and behavioral repertoire. Adult zebrafish were exposed in vivo to three concentrations of GBH Scout®, which contained GLY in formulation (fGLY) (0.065, 1.0 and 10.0 mg L-1 fGLY) for 7 d, and an in vitro assay was performed using also pure GLY. Our results show that GBH induced in zebrafish brain a decrease in cell viability, inhibited mitochondrial complex enzymatic activity, modulated gene expression related to mitochondrial complexes, induced an increase in RS production, promoted hyperpolarization of mitochondrial membrane, and induced behavioral impairments. Together, our data contributes to the knowledge of the neurotoxic effects of GBH. Mitochondrial dysfunction has been recognized as a relevant cellular response that should not be disregarded. Moreover, this study pointed to the mitochondria as an important target of GBH.

Evaluation of apoptosis, oxidative stress responses, AChE activity and body malformations in zebrafish (Danio rerio) embryos exposed to deltamethrin

In this study, we observed the zebrafish embryo/larvae (Danio rerio) exposed to Deltamethrin (DM) used as pesticide in agricultural fields. We determined respectively, changes in body morphology, cell apoptosis, antioxidant enzyme (SOD, CAT, GPx) activities, MDA and acetylcholinesterase (AChE) levels after 96h of DM exposure. The embryos were exposed to 2.5 μg/l - 10 μg/l - 25 μg/l - 50 μg/l of DM concentration for 96 h. Survival and hatching rates, and body malformations were determined under a stereo microscope for in 24, 48, 72 and 96th hours. DM caused the cellular apoptosis and an increase in MDA levels while inhibiting SOD, CAT, GPx enzyme activities and AChE level (P < 0.05). In addition, pericardial edema, yolk sac edema, spinal cord curvature and body malformations were determined in the embryo by depending on the dose of pesticide. As conclusion it can be concluded that DM inhibits the antioxidant enzyme mechanism, increases the cellular apoptosis, malformations. This study may provide enable us for understanding toxic mechanisms of DM in zebrafish embryos.

The effects of Roundup on gametes and early development of common carp (Cyprinus carpio L)

To determine the effects of Roundup, a commercial formulation of glyphosate, gametes, and embryos of common carp (Cyprinus carpio L) was exposed to wide range of herbicide concentrations (0.0, 0.1, 0.5, 2.0, 5.0, 10.0, 20.0, and 50.0 mg/l). The obtained results showed different effects of Roundup on common carp gametes. Herbicide reduced swelling of eggs (but the effect was not concentration-related), while sperm showed low sensitivity to Roundup (time of spermatozoa motility was reduced in a significant way only at 20 mg/l, and at remaining concentrations, only a slight tendency was observed). During the embryonic development, Roundup caused a decrease of common carp embryonic survival (and the effect was concentration-related); however, it had no effect on development rate. During the embryogenesis, three types of embryo body malformation were observed: yolk sac edema, spine curvature, and shortening of body, but their frequencies were not associated with the presence or concentration of herbicide. However, Roundup affected quality of newly hatched larvae of common carp by increasing their mortality. No effect of herbicide on percentage of deformed larvae was observed but larvae hatched in water with Roundup tended to show more complex anomalies compared to those from the control. Obtained data showed that even low concentrations of this herbicide in waters can significantly reduce egg swelling, survival of embryos, and quality of fish larvae.

Effects of glyphosate on early life stages: comparison between Cyprinus carpio and Danio rerio

Glyphosate (N-(phosphonomethyl)glycine) is an active substance of many herbicides. According to literature studies, glyphosate residues and their metabolites have been commonly detected in surface waters and toxicological reports confirmed negative effects on living organisms. In this study, the acute embryo toxicity of glyphosate into two different fish species-common carp (Cyprinus carpio) and zebrafish (Danio rerio)-was investigated. Lethal endpoints, development disorder, and, in addition, other sublethal endpoints such as hatching rate, formation of somites, and development of eyes, spontaneous movement, heartbeat/blood circulation, pigmentation, and edema were recorded to indicate the mode of action of the toxic compound. Hatching retardation (p < 0.05) was observed in experimental groups of common carp exposed to glyphosate with significant statistical difference especially at the highest concentration after 72, 96, and 120 hpf. The significantly highest cumulative mortality at concentration of 50 mg/l was observed. In contrast, hatching stimulation was observed in embryos of zebrafish exposed to the highest concentration of glyphosate. The significantly highest cumulative mortality for zebrafish was observed only at concentration of 50 mg/l. Based on our results, early life stages of common carp are more sensitive in comparison to zebrafish to the toxic action of glyphosate.

A glyphosate micro-emulsion formulation displays teratogenicity in Xenopus laevis

Glyphosate is the active ingredient in broad-spectrum herbicide formulations used in agriculture, domestic area and aquatic weed control worldwide. Its market is growing steadily concurrently with the cultivation of glyphosate-tolerant transgenic crops and emergence of weeds less sensitive to glyphosate. Ephemeral and lentic waters near to agricultural lands, representing favorite habitats for amphibian reproduction and early life-stage development, may thus be contaminated by glyphosate based herbicides (GBHs) residues. Previous studies on larval anuran species highlighted increased mortality and growth effects after exposure to different GBHs in comparison to glyphosate itself, mainly because of the surfactants such as polyethoxylated tallow amine present in the formulations. Nevertheless, these conclusions are not completely fulfilled when the early development, characterized by primary organogenesis events, is considered. In this study, we compare the embryotoxicity of Roundup® Power 2.0, a new GBH formulation currently authorized in Italy, with that of technical grade glyphosate using the Frog Embryo Teratogenesis Assay-Xenopus (FETAX). Our results evidenced that glyphosate was not embryolethal and only at the highest concentration (50 mg a.e./L) caused edemas. Conversely, Roundup® Power 2.0 exhibited a 96 h LC50 of 24.78 mg a.e./L and a 96 h EC50 of 7.8 mg a.e./L. A Teratogenic Index of 3.4 was derived, pointing out the high teratogenic potential of the Roundup® Power 2.0. Specific concentration-dependent abnormal phenotypes, such as craniofacial alterations, microphthalmia, narrow eyes and forebrain regionalization defects were evidenced by gross malformation screening and histopathological analysis. These phenotypes are coherent with those evidenced in Xenopus laevis embryos injected with glyphosate, allowing us to hypothesize that the teratogenicity observed for Roundup® Power 2.0 may be related to the improved efficacy in delivering glyphosate to cells, guaranteed by the specific surfactant formulation. In conclusion, the differences in GBH formulations should be carefully considered by the authorities, since sub-lethal and/or long-term effects (e.g. teratogenicity) can be significantly modulated by the active ingredient salt type and concentration of the adjuvants. Finally, the mechanistic toxicity of glyphosate and GBHs are worthy of further research.

Immunofluorescence evaluation of 4-hydroxynonenal and 8-hydroxy-2-deoxyguanosine activation in zebrafish (Daino rerio) larvae brain exposed (microinjected) to propyl gallate

Propyl gallate (PG) is a chemical compound obtained by esterification of propanol with gallic acid. Due to its antioxidative properties, it is widely used in cosmetics and pharmaceutical industries as well as to protect the oils in foods such as butter, milk-based desserts, chewing gum, mayonnaise, meat, soups, cereals, spices and seasonings from rancidity. This study has been designed to assessment 8-OHdG and 4-HNE activity, and histopathological changes in the brain tissues of zebrafish larvae, which is a lecithotrophic organism, after 96 h of PG exposure via microinjecting to yolk sac of embryo. To this end, approximately 5 nL of various concentrations of PG (1, 10, and 50 ppm) has been injected into yolk sac of fertilized embryo (final exposure concentrations are 5, 50, 250 pg/egg) with micro manipulator system. After 96 h exposure time, propyl gallate caused immunofluorescence positivity of 8-OHdG and 4-HNE in the brain tissues of zebrafish larvae. PG was not effect brain tissue histopathological in low concentrations (1 and 10 ppm) but highest concentration (50 ppm) caused degenerative changes in brain. These results suggests that PG treatment could lead oxidative DNA damage by causing an increase 8-OHdG and 4-HNE activities. This strategy will enable us to better understand the mechanisms of propyl gallate in brain tissues of zebrafish larvae.

Developmental exposure to glyphosate-based herbicide and depressive-like behavior in adult offspring: Implication of glutamate excitotoxicity and oxidative stress

We have previously demonstrated that maternal exposure to glyphosate-based herbicide (GBH) leads to glutamate excitotoxicity in 15-day-old rat hippocampus. The present study was conducted in order to investigate the effects of subchronic exposure to GBH on some neurochemical and behavioral parameters in immature and adult offspring. Rats were exposed to 1% GBH in drinking water (corresponding to 0.36% of glyphosate) from gestational day 5 until postnatal day (PND)-15 or PND60. Results showed that GBH exposure during both prenatal and postnatal periods causes oxidative stress, affects cholinergic and glutamatergic neurotransmission in offspring hippocampus from immature and adult rats. The subchronic exposure to the pesticide decreased L-[14C]-glutamate uptake and increased 45Ca2+ influx in 60-day-old rat hippocampus, suggesting a persistent glutamate excitotoxicity from developmental period (PND15) to adulthood (PND60). Moreover, GBH exposure alters the serum levels of the astrocytic protein S100B. The effects of GBH exposure were associated with oxidative stress and depressive-like behavior in offspring on PND60, as demonstrated by the prolonged immobility time and decreased time of climbing observed in forced swimming test. The mechanisms underlying the GBH-induced neurotoxicity involve the NMDA receptor activation, impairment of cholinergic transmission, astrocyte dysfunction, ERK1/2 overactivation, decreased p65 NF-κB phosphorylation, which are associated with oxidative stress and glutamate excitotoxicity. These neurochemical events may contribute, at least in part, to the depressive-like behavior observed in adult offspring.