Effects of environmentally relevant sub-chronic atrazine concentrations on African clawed frog (Xenopus laevis) survival, growth and male gonad development

Does the atrazine increase animal mortality: Unraveling through a meta-analytic study

Atrazine is one of the most used herbicides in the world, although it is banned in several countries. Pollution of terrestrial and aquatic ecosystems represents a threat to non-target organisms, with various damages already reported in different species. However, there is controversy in studies on atrazine. The question of whether atrazine increases animal mortality is not yet clearly resolved. In this context, this study aimed to carry out a meta-analytic review, focusing on studies on environmental concentrations of the herbicide atrazine to evaluate its lethal effects on various animal species. We identified and analyzed 107 datasets through a selection process that used the Scopus, PubMed, and Web of Science (WoS) databases. A significant increase in the mortality rate of animals exposed to environmental concentrations of atrazine was observed. Nematodes, amphibians, molluscs, insects, and fish showed increased mortality after exposure to atrazine. Animals in the larval and juvenile stages showed greater susceptibility when exposed to different concentrations of atrazine. Furthermore, both commercial and pure formulations resulted in high mortality rates for exposed animals. Atrazine and other pesticides had a synergistic effect, increasing the risk of mortality in animals. There are still many gaps to be filled, and this study can serve as a basis for future regulations involving atrazine.

Estrogen contamination increases vulnerability of amphibians to the deadly chytrid fungus

Aquatic contaminants and infectious diseases are among the major drivers of global amphibian declines. However, the interaction of these factors is poorly explored and could better explain the amphibian crisis. We exposed males and females of the Brazilian Cururu Toad, Rhinella icterica, to an environmentally relevant concentration of the estrogen 17-alpha-ethinylestradiol (an emerging contaminant) and to the chytrid infection (Batrachochytrium dendrobatidis), in their combined and isolated forms, and the ecotoxicity was determined by multiple biomarkers: cutaneous, hematological, cardiac, hepatic, and gonadal analysis. Our results showed that Cururu toads had many physiological alterations in response to the chytrid infection, including the appearance of cutaneous Langerhans's cells, increased blood leukocytes, increased heart contraction force and tachycardia, increased hepatic melanomacrophage cells, which in turn led to gonadal atrophy. The estrogen, in turn, increased the susceptibility of the toads to the chytrid infection (higher Bd loads) and maximized the deleterious effects of the pathogen: reducing leukocytes, decreasing the contraction force, and causing greater tachycardia, increasing hepatic melanomacrophage cells, and leading to greater gonadal atrophy, which were more extreme in females. The exposure to estrogen also revealed important toxicodynamic pathways of this toxicant, as shown by the immunosuppression of exposed animals, and the induction of the first stages of feminization in males, which corroborates that the synthetic estrogen acts as an endocrine disruptor. Such an intricate relationship is unprecedented and reinforces the importance of studying the serious consequences that multiple environmental stressors can cause to aquatic populations.

Behavioral and biochemical consequences after chronic exposition to the herbicide atrazine in tadpoles

Atrazine (ATZ) is the third most sold herbicide in Brazil, occupying the seventh position between most widely used pesticides. Due to its easy outflow, low reactivity and solubility, moderate adsorption to organic matter and clay, and long soil persistence, residual herbicide can be identified after long periods following application, and its usage has been prohibited in diverse countries. Amphibians are important bioindicators to assess impact of pesticide like atrazine, due to having a partial aquatic life cycle. This study had as objective to assess the response of bullfrog (Lithobates catesbeianus) tadpoles when exposed to this herbicide. Animals were exposed for a total of 168h to following concentrations: negative control, 40 μg/L, 200 μg/L, 2000 μg/L, 20000 μg/L of ATZ. Analysis of swimming activity was performed, and biochemical profile was assessed by analysis of blood and plasma glucose levels, urea, creatinine, cholesterol, HDL, triglycerides, glutamic pyruvic transaminase (GPT), alkaline phosphatase (AP), calcium, total proteins, phenol, peroxidase and polyphenol oxidase activity. Results exhibited malnutrition, anemia, likely muscle mass loss, and hepatic damage, indicating that ATZ can lead to an increase in energy to maintain homeostasis for animal survival.

Effects of microplastics on the environmental behaviors of the herbicide atrazine in soil: Dissipation, adsorption, and bioconcentration

As an emerging contaminant in soil, the impact of microplastics (MPs) on the environmental behavior of other organic pollutants remains uncertain, potentially threatening the sustainability of agricultural production. In this study, the impact of two kinds of MPs on the environmental behaviors of herbicide atrazine in soil-plant system was investigated. The results showed that MPs significantly reduced the half-life 17.69 ∼ 21.86 days of atrazine in the soil, compared to the control group. Meanwhile, the introduction of MPs substantially increased atrazine adsorption. Additionally, MPs substantially enriched the diversity and functionality of soil microbiome, and the soil metabolic activity was stimulated. Regarding the crop growth, the accumulation of atrazine in maize were significantly decreased by approximately 48.4-78.5 % after exposure to MPs. In conclusion, this study reveals the impact of MPs on atrazine's environmental behaviors in soil and highlights their less effect on maize growth, providing valuable insights for managing MPs contamination in sustainable agriculture.

Effect of atrazine on testicular toxicity involves accommodative disorder of xenobiotic metabolizing enzymes system and testosterone synthesis in European quail (Coturnix coturnix)

Due to the wide use of atrazine (ATR), the concern has increased regarding the negative impact of ATR on reproduction. Nevertheless, the reproductive effects caused by different exposure concentrations and the severity of toxic damage are poorly understood. In organisms, ATR is metabolized and degraded through phase II enzyme systems, and changes in cytochrome P450 (CYP) enzymes may have a regulatory role in the harm of ATR. However, less information is available on the induction of CYPs by ATR in avian organisms, and even less on its effects on the testis. Birds are exposed to ATR mainly through food residues and contaminated water, the purpose of this study was to examine reproductive toxicity by different exposure concentrations and elaborate metabolic disorders caused by ATR in European quail (Coturnix coturnix). In this study, the quail were given ATR at 50 mg/kg, 250 mg/kg and 500 mg/kg by oral gavage for 45 days, and the testicular weight coefficients, histopathology and ultrastructure of testes, primary biochemical functions, sex steroid hormones, critical protein levels in the testosterone synthesis pathway, the expression of genes involved CYPs, gonad axis and nuclear receptors expression were investigated. Altogether, testicular coefficient decreased significantly in the high-dose group (1.22%) compared with the control group (3.03%) after 45 days of ATR exposure, and ATR is a potent CYP disruptor that acts through the NXRs and steroid receptor subfamily (APND, CAR, ERND and ERα) without a dose-dependent manner. Notably, ATR interfered with the homeostasis of hormones by triggering the expression of hormones on the gonad axis (LH and E2). These results suggest that exposure to ATR can cause testicular toxicity involving accommodative disorder of phase II enzyme and testosterone synthesis in European quail.

Influences of continuous and pulse atrazine exposure on intestinal flora and metabolites of Pelophylax nigromaculatus tadpoles

Atrazine, a widely used herbicide, has adverse effects on the growth and metabolism of amphibians. Due to the cyclical application use of the pesticide atrazine in agricultural production, atrazine concentrations in water occur in the form of pulses. However, knowledge of the effects of atrazine pulse exposure on the gut microbiota and metabolism of amphibians is limited. In this study, Pelophylax nigromaculatus tadpoles (Gs 26) were exposed to continuous and pulse atrazine (100 μg/L) for 60 days. The results showed that continuous exposure and pulse exposure had different effects on the diversity of gut microbiota. At the phyla level, pulse exposure significantly increased the relative abundance of Actinobacteria, and decreased the relative abundance of Firmicutes compared to continuous exposure. At the genus level, continuous and pulse exposure to atrazine significantly altered the relative abundance of Acetobacterium, Microbacterium, Bacteroides, Eulopiscium and Leuconostoc. Compared to continuous exposure, pulse exposure significantly increased the relative abundance of Microbacterium, and significantly decreased the relative abundance of Acetobacterium and Eplopiscium. In terms of metabolism, pulse exposure significantly increased the relative abundance of creatine, guanine, and inosine and significantly decreased the relative abundance of 3-hydroxysebacic acid, ganoderic acid F, hypoxanthine, and withaperuvin H compared to continuous exposure. Continuous and pulse exposure to atrazine significantly altered the relative abundance of metabolites of the pymidine metabolism, purine metabolism, beta-alanine metabolism and other pathways in the gut of P. nigromaculatus tadpoles. In addition, changes in most metabolites had a significant correlation with changes in gut microorganisms. In conclusion, our study confirmed that pulse exposure to atrazine has a greater effect on the composition of the gut microflora and the metabolism of P. nigromaculatus tadpoles than continuous exposure.

Xenopus laevis (Daudin, 1802) as a Model Organism for Bioscience: A Historic Review and Perspective

In vitro systems have been mainly promoted by authorities to sustain research by following the 3Rs principle, but continuously increasing amounts of evidence point out that in vivo experimentation is also of extreme relevance. Xenopus laevis, an anuran amphibian, is a significant model organism in the study of evolutionary developmental biology, toxicology, ethology, neurobiology, endocrinology, immunology and tumor biology; thanks to the recent development of genome editing, it has also acquired a relevant position in the field of genetics. For these reasons, X. laevis appears to be a powerful and alternative model to the zebrafish for environmental and biomedical studies. Its life cycle, as well as the possibility to obtain gametes from adults during the whole year and embryos by in vitro fertilization, allows experimental studies of several biological endpoints, such as gametogenesis, embryogenesis, larval growth, metamorphosis and, of course, the young and adult stages. Moreover, with respect to alternative invertebrate and even vertebrate animal models, the X. laevis genome displays a higher degree of similarity with that of mammals. Here, we have reviewed the main available literature on the use of X. laevis in the biosciences and, inspired by Feymann's revised view, "Plenty of room for biology at the bottom", suggest that X. laevis is a very useful model for all possible studies.

Atrazine contaminated sites and bullfrog tadpoles: evasive trends and biochemical consequences

Atrazine (ATZ) is one of the most used active principles in agricultural systems. This pesticide has the ability to easily accumulate in terrestrial and aquatic environments, causing impacts with chronic adverse effects. Avoidance tests are tests that seek to assess the concentration from which a given organism escapes, that is, migrates to another habitat. They are being used as a modality of innovative and minimally invasive ecotoxicological tests. Our objective was to evaluate the sensitivity and possible toxic effects of ATZ in bullfrog tadpoles (Lithobates catesbeianus), through avoidance tests and oxidative stress analyses. We performed the behavioral avoidance test lasting 12 h, with observations every 60 min in a linear multi-compartment system with seven compartments. Each compartment corresponded to a concentration: negative control, 1, 2, 20, 200, 2000, 20,000 µg L^-1. After the selection of habitat, organisms were forcedly maintained in the chosen concentrations for 48 h and then, metabolic effects were measured assessing the blood plasma amino acid profile and liver protein degradation. We also determined the effective concentrations of ATZ tested at 0 h and 48 h. The results showed that there was an effect of the treatment on the distribution of tadpoles, but not on the hours or on the combined effect (interaction). The biochemical analyses also showed a concentration-dependent relationship which caused significant toxic effects even in a short period of time. In conclusion, these frogs were able to avoid places with high concentrations of ATZ in the first hours of exposure, which suggests that in the natural environment these animals can migrate or avoid areas contaminated by this herbicide; however, depending on the selected concentration, serious biochemical consequences can occur.

Does atrazine induce changes in predator recognition, growth, morphology, and metamorphic traits of larval skipper frogs (Euphlyctis cyanophlyctis)?

Atrazine, an info disruptor, interferes with the olfaction of aquatic organisms by impairing the chemosensory system. Consequently, it affects behavior, physiology, and growth increases mortality and infections, and suppresses the immune system of aquatic animals. In this study, we wanted to determine the sensitivity of larval Euphlyctis cyanophlyctis to different concentrations of atrazine by assessing their antipredator behavior, growth, morphology, and metamorphic traits. The results indicate that exposure to atrazine did not affect the survival of tadpoles. However, it caused retarded growth at higher concentrations. Interestingly, the antipredator behavior of tadpoles toward conspecific alarm cues decreased in a dose-dependent manner with an increase in the concentration of atrazine. Tadpoles exposed to low concentrations of atrazine had deeper, wider bodies and tails while those exposed to higher concentrations had shallower and narrower bodies with shallower tail muscles. However, at low and moderate concentrations atrazine did not affect size at metamorphosis, it extended the larval duration at higher concentrations.

DNA methylation 6 mA and histone methylation involved in multi-/trans-generational reproductive effects in Caenorhabditis elegans induced by Atrazine

Atrazine (ATR), a widely used triazine herbicide, is an environmental endocrine disruptor that can cause health problems. However, whether there are multi/trans-generational reproductive impacts of ATR have not been studied. Therefore, in this study, Caenorhabditis elegans was used as a preferable model organism to identify the multi/trans-generational reproductive toxicity of ATR. Only parental C.elegans (P0) were exposed to different concentrations (0.0004-40 mg/L) for 48 h and the subsequent offspring (F1-F5) were grown under ATR-free conditions and ATR conditions.The results showed that ATR exposure during P0 decreased fecundity, including a reduction in fertilized eggs, oocytes, and ovulation rate, delayed gonadal development, and decreased the relative area of gonad arm and germ cell number. Furthermore, continuous ATR exposure (P0-F5) causes a significant increase in reproductive toxicity in subsequent generations, although no significant toxicity occurred in the P0 generation after exposure to environmental-related concentrations, suggesting that ATR exposure might have cumulative effects. Likewise, parental exposure to ATR caused transgenerational toxicity impairments. Interestingly, only reproductive toxicity, not development toxicity, was transmitted to several generations (F1-F4), and the F2 generation showed the most notable changes. QRT-PCR results showed that genes expression related to DNA methylation 6 mA (damt-1, nmad-1) and histone H3 methylation (mes-4, met-2, set-25, set-2, and utx-1) can also be passed on to offspring. The function of H3K4 and H3K9 methylation were explored by using loss-of-function mutants for set-2, set-25, and met-2. Transmissible reproductive toxicity was absent in met-2(n4256), set-2(ok952), and set-25(n5021) mutants, which suggests that the histone methyltransferases H3K4 and H3K9 activity are indispensable for the transgenerational effect of ATR. Finally, the downstream genes of DNA methylation and histone H3 methylation were determined. ATR upregulated the expression of ZC317.7, hsp-6, and hsp-60. Mitochondrial stress in parental generation dependent transcription 6 mA modifiers may establish these epigenetic marks in progeny.

The role of effect-based methods to address water quality monitoring in South Africa: a developing country's struggle

Water is an important resource, and it is a worldwide struggle to provide water of good quality to the whole population. Despite good governing laws and guidelines set in place to help protect the water resources and ensure it is of good quality for various consumers, the water quality in South Africa is worsening due to lack of management. The deteriorating infrastructure is becoming progressively worse, due to corruption and insufficient funds. The ever-increasing number of toxicants, as well as the identification of emerging chemicals of concern, are also challenges South Africa is facing. Chemical analysis cannot determine the total biological effect of a mixture of chemical compounds, but this shortcoming can be addressed by adding effect-based methods (EBMs) to water quality monitoring programmes. In this paper, the current status of water quality monitoring in South Africa is discussed, as well as the capacity of the country to add EBMs to its water quality monitoring programmes to protect and improve human and animal life. Created in Biorender.com.

Atrazine and estradiol effects on development of Acris blanchardi (Blanchard's cricket frog) exposed in outdoor enclosures

BACKGROUND

The herbicide atrazine has been proposed as a potential endocrine disrupting compound (EDC) for amphibians. Using atrazine concentrations below or at those typically found in surface waters (0.5, 5.0, 50 μg/L), we exposed Acris blanchardi (Blanchard's cricket frog) larvae throughout development until metamorphosis (i.e. Gosner stages 26-45). An additional 50 μg/L treatment (50s μg/L) was utilized where supplemented algae was added to control for indirect atrazine effects from reduced food sources. In addition to atrazine, experimental groups also included a negative control and two positive controls, 17β-estradiol (E2) at 2.3 and 25 μg/L. At 60 days post-metamorphosis, A. blanchardi metamorphs were euthanized for analysis of gross and histopathological development.

RESULTS

Atrazine did not significantly influence mortality (mean recovery of 54% across treatments), sex ratio, body mass (BM), snout-vent length (SVL), gonad size, nor gonad development of A. blanchardi. Females exposed to 50s μg/L atrazine had 29% less mass, were 10% shorter, and had a 29% lower mean ovary area (mm² ) as compared to negative controls, suggesting algae enrichment had a significant negative effect. Males exposed to estradiol (25 μg/L) showed an increased level of oviduct development. Ovary area was also significantly influenced by estradiol treatment at 2.3 and 25 μg/L.

CONCLUSION

Overall, estradiol had much less effect than predicted based on other model species (e.g. Xenopus laevis). Development of A. blanchardi, overall, was not affected by long-term exposure to environmentally relevant concentrations of atrazine. However, this species also was largely insensitive to exogenous estradiol in this test system. © 2022 Society of Chemical Industry.

Growth, biofilm formation and atrazine degrading gene (trzN) expression of Arthrobacter sp. DNS10 cultured with montmorillonite, kaolinite and goethite

The viable and degradation potential of the strains which adhered to soil minerals are essential for eliminating organic pollutants from soil. Herein, the interaction (growth, biofilm formation and survive) of Arthrobacter sp. DNS10, an atrazine degrading strain, with three kinds of typical soil minerals, such as montmorillonite, kaolinite and goethite, as well as the atrazine degradation gene (trzN) expression of the strain in the minerals system were studied. The results showed that montmorillonite had significant promotion effect on the growth of strain DNS10, followed by kaolinite, but goethite significantly inhibited the growth of strain DNS10. In contrast, goethite notably promoted the biofilm formation and there was less biofilm detected in montmorillonite containing system. The percentage of the survival bacteria in the biofilm that formed on montmorillonite, kaolinite and goethite was 53.8%, 40.8% and 28.2%. In addition, there were more reactive oxygen species (ROS) were detected in the cells that exposed to goethite than those of the cells exposed to kaolinite and montmorillonite. These results suggest that the electrostatic repulsion between kaolinite/montmorillonite and strain DNS10 prevents them from contacting each other and facilitates bacterial growth by allowing the strain to obtain more nutrients. Oppositely, the needle-like morphology of goethite might damage the strain DNS10 cell when they were combined by electrostatic attraction, and the goethite induced ROS also aggravate the cytotoxicity of goethite on strain DNS10. In addition, the relative transcription of trzN in the cells contacted with montmorillonite, kaolinite and goethite was 0.94-, 0.27- and 0.20- fold of the no mineral exposure treatment. Briefly, this research suggests that the minerals with different structure and/or physicochemical characteristics might cause various trend for the biofilm formation and degradation potential of the bacteria.

Toxicological effects, environmental behaviors and remediation technologies of herbicide atrazine in soil and sediment: A comprehensive review

Atrazine has become one of the most popular applied triazine herbicides in the world due to its high herbicidal efficiency and low price. With its large-dosage and long-term use on a global scale, atrazine can cause widespread and persistent contamination of soil and sediment. This review systematically evaluates the toxicological effects, environmental risks, environmental behaviors (adsorption, transport and transformation, and bioaccumulation) of atrazine, and the remediation technologies of atrazine-contaminated soil and sediment. For the adsorption behavior of atrazine on soil and sediment, the organic matter content plays an extremely important role in the adsorption process. Various models and equations such as the multi-media fugacity model and solute transport model are used to analyze the migration and transformation process of atrazine in soil and sediment. It is worth noting that certain transformation products of atrazine in the environment even have stronger toxicity and mobility than its parent. Among various remediation technologies, the combination of microbial remediation and phytoremediation for atrazine-contaminated soil and sediment has wide application prospects. Although other remediation technologies such as advanced oxidation processes (AOPs) can also efficiently remove atrazine from soil, some potential problems still need to be further clarified. Finally, some related challenges and prospects are proposed.

Biochemical and cellular responses of the freshwater mussel, Hyriopsis bialata, to the herbicide atrazine

The present study aimed to evaluate biochemical and cellular responses of the freshwater mussel, Hyriopsis bialata, to the herbicide atrazine (ATZ). The mussels were exposed to environmentally-relevant concentrations of ATZ (0, 0.02 and 0.2 mg/L) and a high concentration (2 mg/L) for 0, 7, 14, 21 and 28 days. Tissues comprising male and female gonads, digestive glands and gills were collected and assessed for ethoxyresorufin-O-deethylase (EROD) activity, glutathione S-transferase (GST) activity, multixenobiotic resistance mechanism (MXR), histopathological responses, DNA fragmentation and bioaccumulation of ATZ and its transformation derivatives, desethylatrazine (DEA) and desisopropylatrazine (DIA). Additionally, circulating estradiol levels were determined. It appeared that ATZ did not cause significant changes in activities of EROD, GST and MXR. There were no apparent ATZ-mediated histopathological effects in the tissues, with the exception of the male gonads exhibiting aberrant aggregation of germ cells in the ATZ-treated mussels. Contrarily, ATZ caused significant DNA fragmentation in all tissues of the treated animals in dose- and time-dependent manners. In general, the circulating estradiol levels were higher in the females than in the males. However, ATZ-treated animals did not show significant alterations in the hormonal levels, as compared with those of the untreated animals. Herein, we showed for the first time differentially spatiotemporal distribution patterns of bioaccumulation of ATZ, DEA and DIA, with ATZ and DEA detectable in the gonads of both sexes, DEA and DIA in the digestive glands and only DEA in the gills. The differential distribution patterns of bioaccumulation of ATZ and its derivatives among the tissues point to different pathways and tissue capacity in transforming ATZ into its transformation products. Taken together, the freshwater mussel H. bialata was resistant to ATZ likely due to their effective detoxification. However, using DNA damage as a potential biomarker, H. bialata is a promising candidate for biomonitoring aquatic toxicity.

Biodegradation of 4-nitroaniline by novel isolate Bacillus sp. strain AVPP64 in the presence of pesticides

In this study, Bacillus sp. strain AVPP64 was isolated from diuron-contaminated soil. It showed 4-nitroaniline (4-NA) degradation, pesticide tolerance, and self-nutrient integration via nitrogen (N)-fixation and phosphate (P)-solubilization. The rate constant (k) and half-life period (t_1/2) of 4-NA degradation in the aqueous medium inoculated with strain AVPP64 were observed to be 0.445 d^-1 and 1.55 d, respectively. Nevertheless, in the presence of chlorpyrifos, profenofos, atrazine and diuron pesticides, strain AVPP64 degraded 4-NA with t_1/2 values of 2.55 d, 2.26 d, 2.31 d and 3.54 d, respectively. The strain AVPP64 fixed 140 μg mL^-1 of N and solubilized 103 μg mL^-1 of P during the presence of 4-NA. In addition, strain AVPP64 produced significant amounts of plant growth-promoting metabolites like indole 3-acetic acid, siderophores, exo-polysaccharides and ammonia. In the presence of 4-NA and various pesticides, strain AVPP64 greatly increased the growth and biomass of Vigna radiata and Crotalaria juncea plants. These results revealed that Bacillus sp. strain AVPP64 can be used as an inoculum for bioremediation of 4-NA contaminated soil and sustainable crop production even when pesticides are present.

Degradation of the typical herbicide atrazine by UV/persulfate: kinetics and mechanisms

Atrazine (ATZ), a widely used herbicide, had received a significant amount of attention due to its widespread detection in aquatic environments as well as its potential risks to human health. UV/persulfate (PS) process is an emerging technology for degrading organic pollutants in water. Thus, the degradation of ATZ by a UV/PS process was investigated in this study. The results showed that the removal rate of ATZ was 98.4% with a PS dosage of 2 mg/L and an initial ATZ concentration of 0.1 mg/L. In addition, a relatively high degradation efficiency was obtained under pH = 7. However, the addition of humic acid (HA) reduced the removal rate of ATZ. Hydroxyl radicals (•OH) and sulfate radicals (•SO₄^-) respectively contributed to 21.7% and 29% of the ATZ degradation. The ATZ degradation pathway was proposed, and the main reactions of ATZ in this UV/PS process included dechlorination, demethylation, and deethylation. Moreover, the toxicity of ATZ and its degradation products was assessed using the Toxicity Estimation Software Tool (TEST), and the results showed that the toxicity of the ATZ solution was reduced after the UV/PS process. These results indicate that UV/PS shows good promise as a remediation technique for the treatment of persistent herbicides such as ATZ in contaminated water.

Heat/PMS Degradation of Atrazine: Theory and Kinetic Studies

The degradation effect of heat/peroxymonosulfate (PMS) on atrazine (ATZ) is studied. The results show that the heat/PMS degradation for ATZ is 96.28% at the moment that the phosphate buffer (PB) pH, temperature, PMS dosage, ATZ concentration, and reaction time are 7, 50 °C, 400 μmol/L, 2.5 μmol/L, and 60 min. A more alkaline PB is more likely to promote the breakdown of ATZ through heat/PMS, while the PB alone has a more acidic effect on the PMS than the partially alkaline solution. HO• and SO4−• coexisted within the heat/PMS scheme, and ATZ quantity degraded by HO• and SO4−• in PB with pH = 7, pH = 1.7~1. HCO3− makes it difficult for heat/PMS to degrade ATZ according to inorganic anion studies, while Cl− and NO3− accelerate the degradation and the acceleration effect of NO3− is more obvious. The kinetics of ATZ degradation via heat/PMS is quasi-first-order. Ethanol (ETA) with the identical concentration inhibited ATZ degradation slightly more than HCO3−, and both of them reduced the degradation rates of heat/PMS to 7.06% and 11.56%. The addition of Cl− and NO3− increased the maximum rate of ATZ degradation by heat/PMS by 62.94% and 189.31%.

Atrazine exposure and recovery alter the intestinal structure, bacterial composition and intestinal metabolites of male Pelophylax nigromaculatus

The pesticide atrazine poses a potential threat to the health of frogs living in farmland areas. The exposure concentration in traditional pesticide experiments is usually constant, while pesticide pollution in actual water may fluctuate due to periodic or seasonal application. We examined the effects of different concentrations of atrazine (50, 100 and 500 μg/L) over a 14-day exposure and a 7-day recovery on intestinal histology, bacterial composition and intestinal metabolites of male Pelophylax nigromaculatus. HE staining revealed that after a 14-day atrazine exposure, the 100 μg/L and 500 μg/L groups showed obvious cysts and significantly decreased intestinal crypt depth and villus height. After a 7-day recovery, the damaged intestine in the 100 μg/L group was partially recovered, while in the 500 μg/L exposure group there was no improvement. 16S rRNA gene analysis of intestinal bacteria showed that 500 μg/L atrazine exposure significantly caused a persistent decrease in bacterial α diversity. Compared to the control and other atrazine exposure groups, the 500 μg/L group showed significant changes in the relative abundance of predominant bacteria. In addition, most dominant bacteria in the 500 μg/L recovery group showed significant differences with the 50 μg/L and 100 μg/L recovery groups. Nontargeted metabolomics profiling based on UPLC/MS analysis showed that atrazine exposure and recovery induced changes in the intestinal metabolic profile. The changes in metabolites were mainly related to purine/pyrimidine metabolism, glycine, serine and threonine metabolism, and arginine and proline metabolism. In general, these pathways were closely related to energy metabolism and amino acid metabolism. These results suggest that the short-term exposure to 500 μg/L atrazine causes persistent harm to intestinal health. This study is an important step toward a better understanding of the toxic effects of atrazine exposure and recovery in frog intestines.

Current use pesticides in soil and air from two agricultural sites in South Africa: Implications for environmental fate and human exposure

Concerns about the possible negative impacts of current use pesticides (CUPs) for both the environment and human health have increased worldwide. However, the knowledge on the occurrence of CUPs in soil and air and the related human exposure in Africa is limited. This study investigated the presence of 30 CUPs in soil and air at two distinct agricultural sites in South Africa and estimated the human exposure and related risks to rural residents via soil ingestion and inhalation (using hazard quotients, hazard index and relative potency factors). We collected 12 soil and 14 air samples over seven days during the main pesticide application season in 2018. All samples were extracted, purified and analyzed by high-performance liquid chromatography coupled with tandem mass spectrometry. In soils, nine CUPs were found, with chlorpyrifos, carbaryl and tebuconazole having the highest concentrations (up to 63.6, 1.10 and 0.212 ng g^-1, respectively). In air, 16 CUPs were found, with carbaryl, tebuconazole and terbuthylazine having the highest levels (up to 25.0, 22.2 and 1.94 pg m^-3, respectively). Spatial differences were observed between the two sites for seven CUPs in air and two in soils. A large dominance towards the particulate phase was found for almost all CUPs, which could be related to mass transport kinetics limitations (non-equilibrium) following pesticide application. The estimated daily intake via soil ingestion and inhalation of individual pesticides ranged from 0.126 fg kg^-1 day^-1 (isoproturon) to 14.7 ng kg^-1 day^-1 (chlorpyrifos). Except for chlorpyrifos, soil ingestion generally represented a minor exposure pathway compared to inhalation (i.e. <5%). The pesticide environmental exposure largely differed between the residents of the two distinct agricultural sites in terms of levels and composition. The estimated human health risks due to soil ingestion and inhalation of pesticides were negligible although future studies should explore other relevant pathways.

The effect of atrazine on intestinal histology, microbial community and short chain fatty acids in Pelophylax nigromaculatus tadpoles

The intestine is the main organ for nutrient absorption in amphibians. It is sensitive to atrazine, which is a herbicide widely used in agricultural areas. At present, there is a lack of systematic research on the effect of atrazine on the amphibian intestine. In this study, we evaluated the effects of atrazine exposure (0, 50 μg/L, 100 μg/L, and 500 μg/L) for 20 days on intestinal histology, microbiota and short chain fatty acids in Pelophylax nigromaculatus tadpoles. Our research showed that 500 μg/L atrazine exposure significantly decreased the height of microvilli and epithelial cells, and altered the composition and diversity of intestinal microbiota in P. nigromaculatus tadpoles compared to the control. At the phylum level, the abundance of Bacteroidetes and Fusobacteria increased significantly, while that of Verrucomicrobia and Firmicutes decreased significantly in the 500 μg/L atrazine treatment group. At the genus level, Akkermansia and Lactococcus had significantly lower abundance in the 100 μg/L and 500 μg/L atrazine exposure group, while Cetobacterium was only detected in the 100 μg/L and 500 μg/L atrazine treated group. Also, function prediction of intestinal microbiota showed that atrazine treatment significantly changed the metabolism pathways of P. nigromaculatus tadpoles. In addition, 500 μg/L atrazine exposure changed the content of short chain fatty acids by significantly increasing the content of total SFCAs, butyric acid, and valeric acid, and decreasing the content of isovaleric acid in the intestine. Taken together, atrazine exposure could affect the intestinal histology and induce intestinal microbiota imbalance and metabolic disorder in amphibian tadpoles.

Herbicide atrazine exposure induce oxidative stress, immune dysfunction and WSSV proliferation in red swamp crayfish Procambarus clarkii

Atrazine is considered as a potential environmental endocrine disruptors and exhibits various toxic effects on animals. It has a great impact in the aquatic ecosystems, but there are few studies on its immunotoxicity in crustaceans. In the present study, the Procambarus clarkii were utilized to assess the immune toxicity after 0.5 mg/L and 5 mg/L atrazine exposure. A significant decrease in total hemocytes count (THC) was observed at 5 mg/L atrazine exposure throughout the experiment. The activities of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were significantly inhibited, but the content of reactive oxygen species (ROS) and malondialdehyde (MDA) were up-regulated, indicating the potential oxidative stress. The analysis of the integrated biomarker response (IBR) showed the induction of oxidative stress biomarkers and the inhibition of antioxidants. After 5 mg/L atrazine exposure for 144 h, the integrity of crayfish hepatopancreas was destroyed with disappeared connections between tubules and increased liver tubules vacuoles. The relative expression levels of different immune genes in hepatopancreas after atrazine exposure were measured. Most of these genes were suppressed and exhibited a certain dose-dependent effect. The results of crayfish white spot syndrome virus (WSSV) replication shown the amount of virus in muscle was significantly higher and exhibited a higher mortality rate at 5 mg/L group than other groups. The present study determined the impact of atrazine exposure on WSSV outbreaks, and also provide an important basis for further assessing the occurrence of pesticides on diseases of P. clarkii.

Effects of atrazine short-term exposure on jumping ability and intestinal microbiota diversity in male Pelophylax nigromaculatus adults

Atrazine, a common chemical pesticide, has toxicity to adult and juvenile amphibians in natural ecosystems; however, it is more common to study its effects on larvae instead of adults. This study assessed the impacts of atrazine in water through short-term exposure (7 days) on male black spotted frog (Pelophylax nigromaculatus) adults fed every day. The jumping ability, including jumping height, distance, time, and speed, was measured by 3D motion analysis software, and the intestinal content microbiota was determined by 16S rRNA amplicon sequencing with QIIME software. The results showed that male P. nigromaculatus exposure to 200 and 500 μg/L atrazine significantly increased jumping distance and jumping time compared to control groups. Conversely, 500 μg/L atrazine treatments significantly decreased the diversity and changed the composition and structure of intestinal content microflora in male P. nigromaculatus compared to control groups. At the phylum level, Chlamydiae was only detected in the control group, and Actinobacteria, Bacteroidetes, Firmicutes, Fusobacteria, and Proteobacteria were the dominant microflora in the atrazine treatment groups. At the genus level, the abundance of Lactobacillus and Weissella significantly increased in atrazine treatment groups compared to control groups. This study can provide a new framework based on movement behavior and intestinal microbiota to evaluate the response of amphibians to short-term exposure to environmental pollution.

Pesticide-induced multigenerational effects on amphibian reproduction and metabolism

Underlying drivers of species extinctions need to be better understood for effective conservation of biodiversity. Nearly half of all amphibian species are at risk of extinction, and pollution may be a significant threat as seasonal high-level agrochemical use overlaps with critical windows of larval development. The potential of environmental chemicals to reduce the fitness of future generations may have profound ecological and evolutionary implications. This study characterized effects of male developmental exposure to environmentally relevant concentrations of the anti-androgenic pesticide linuron over two generations of offspring in Xenopus tropicalis frogs. The adult male offspring of pesticide-exposed fathers (F1) showed reduced body size, decreased fertility, and signs of endocrine system disruption. Impacts were further propagated to the grand-offspring (F2), providing evidence of transgenerational effects in amphibians. The adult F2 males demonstrated increased weight and fat body palmitoleic-to-palmitic acid ratio, and decreased plasma glucose levels. The study provides important cross-species evidence of paternal epigenetic inheritance and pollutant-induced transgenerational toxicity, supporting a causal and complex role of environmental contamination in the ongoing species extinctions, particularly of amphibians.

The Atrazine Saga and its Importance to the Future of Toxicology, Science, and Environmental and Human Health

The herbicide atrazine is one of the most commonly used, well studied, and controversial pesticides on the planet. Much of the controversy involves the effects of atrazine on wildlife, particularly amphibians, and the ethically questionable decision making of members of industry, government, the legal system, and institutions of higher education, in most cases in an effort to "bend science," defined as manipulating research to advance economic, political, or ideological ends. In this Critical Perspective I provide a timeline of the most salient events in the history of the atrazine saga, which includes a multimillion-dollar smear campaign, lawsuits, investigative reporting, accusation of impropriety against the US Environmental Protection Agency, and a multibillion-dollar transaction. I argue that the atrazine controversy must be more than just a true story of cover-ups, bias, and vengeance. It must be used as an example of how manufacturing uncertainty and bending science can be exploited to delay undesired regulatory decisions and how greed and conflicts of interest-situations where personal or organizational considerations have compromised or biased professional judgment and objectivity-can affect environmental and public health and erode trust in the discipline of toxicology, science in general, and the honorable functioning of societies. Most importantly, I offer several recommendations that should help to 1) prevent the history of atrazine from repeating itself, 2) enhance the credibility and integrity of science, and 3) enrich human and environmental health. Environ Toxicol Chem 2021;40:1544-1558. © 2021 SETAC.

Aquaculture-derived distribution, partitioning, migration, and transformation of atrazine and its metabolites in seawater, sediment, and organisms from a typical semi-closed mariculture bay

Atrazine (ATR) is one of the most commonly used herbicides that could directly impair the growth and health of organisms in mariculture areas and adversely affect human health through the food chain. This study investigated the contaminant occurrence, migration, and transformation of ATR and three of its chlorinated metabolites, namely deethylatrazine (DEA), deisopropylatrazine (DIA), and didealkylatrazine (DDA), in surface seawater, sediment, and aquatic organisms from the Xiangshan Harbor. ATR was detected in all samples, while DIA and DDA were only respectively detected in aquatic and seawater samples. The distribution of ATR and its metabolites presented different patterns depending on the geographic location and showed a higher level in the aquaculture area than that in the non-aquaculture area. The bioaccumulation of ATR in aquaculture organisms showed that benthic organisms, such as Ditrema, and Sinonovacula constricta (Sin), had increased levels. The ecological risks indicated that ATR posed medium or high risks to algae in the water phase of the study area. The microcosm experiment showed that the main fate of ATR in the simulated microenvironment was sedimentation, which followed the first-order kinetic equation. The ATR in the sediment could be enriched 3-5 times in Sin, and its major metabolites were DEA and DIA.

Nicosulfuron inhibits atrazine biodegradation by Arthrobacter sp. DNS10:Influencing mechanisms insight from bacteria viability, gene transcription and reactive oxygen species production

Nicosulfuron is a sulfonylurea family herbicide which is commonly applied together with the triazine herbicide atrazine in agricultural practice. However, whether nicosulfuron can influence the biodegradation of atrazine is unclear. Therefore, the influence of nicosulfuron on atrazine removal as well as on cell viability and transcription of atrazine chlorohydrolase gene (trzN) in Arthrobacter sp. DNS10 was investigated in this study. Our results demonstrated that 76.0% of atrazine was degraded in the absence of nicosulfuron after 48h of culture, whereas 63.9, 49.1 and 42.6% was degraded in the presence of 1, 5, and 10 mg/L of nicosulfuron, respectively. Nicosulfuron also induced an increase in the level of intracellular reactive oxygen species (ROS), thereby damaging the cell membrane integrity and inhibiting the growth of the strain DNS10. Flow cytometry analysis revealed that the cell viability of strain DNS10 decreased with an increase in nicosulfuron concentration. The transcription of trzN in strain DNS10 exposed to the three described levels of nicosulfuron was 0.99, 0.72 and 0.52 times, respectively, that without nicosulfuron. In brief, nicosulfuron could inhibit atrazine removal efficiency by strain DNS10 by inducing the over-production of ROS which ultimately enhances the population of membrane-damaged cells, as well as reducing cell viability and trzN transcription. The outcomes of the present study provide new insights into the mechanism of nicosulfuron inhibition on atrazine biodegradation by strain DNS10.

Agrochemicals in freshwater systems and their potential as endocrine disrupting chemicals: A South African context

South Africa is the largest agrochemical user in sub-Saharan Africa, with over 3000 registered pesticide products. Although they reduce crop losses, these chemicals reach non-target aquatic environments via leaching, spray drift or run-off. In this review, attention is paid to legacy and current-use pesticides reported in literature for the freshwater environment of South Africa and to the extent these are linked to endocrine disruption. Although banned, residues of many legacy organochlorine pesticides (endosulfan and dichlorodiphenyltrichloroethane (DDT)) are still detected in South African watercourses and wildlife. Several current-use pesticides (triazine herbicides, glyphosate-based herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D) and chlorpyrifos) have also been reported. Agrochemicals can interfere with normal hormone function of non-target organism leading to various endocrine disrupting (ED) effects: intersex, reduced spermatogenesis, asymmetric urogenital papillae, testicular lesions and infertile eggs. Although studies investigating the occurrence of agrochemicals and/or ED effects in freshwater aquatic environments in South Africa have increased, few studies determined both the levels of agricultural pesticides present and associated ED effects. The majority of studies conducted are either laboratory-based employing in vitro or in vivo bioassays to determine ED effects of agrochemicals or studies that investigate environmental concentrations of pesticides. However, a combined approach of bioassays and chemical screening will provide a more comprehensive overview of agrochemical pollution of water systems in South Africa and the risks associated with long-term chronic exposure.

Xenopus in revealing developmental toxicity and modeling human diseases

The Xenopus model offers many advantages for investigation of the molecular, cellular, and behavioral mechanisms underlying embryo development. Moreover, Xenopus oocytes and embryos have been extensively used to study developmental toxicity and human diseases in response to various environmental chemicals. This review first summarizes recent advances in using Xenopus as a vertebrate model to study distinct types of tissue/organ development following exposure to environmental toxicants, chemical reagents, and pharmaceutical drugs. Then, the successful use of Xenopus as a model for diseases, including fetal alcohol spectrum disorders, autism, epilepsy, and cardiovascular disease, is reviewed. The potential application of Xenopus in genetic and chemical screening to protect against embryo deficits induced by chemical toxicants and related diseases is also discussed.

Qualitative assessment of 27 current-use pesticides in air at 20 sampling sites across Africa

Increasing use of current-use pesticides (CUPs) in Africa raises environmental and public health concerns. But there is a large uncertainty about their occurrence and the composition of pesticide mixtures on this continent. This paper investigates the presence of 27 CUPs in air across 20 sampling sites in Africa. 166 passive air samples, consisting of polyurethane foam (PUF), were collected in 12 African countries between 2010 and 2018. Samples were extracted with methanol and analyzed via high-performance liquid chromatography coupled with tandem mass spectrometry. The detection frequencies of CUPs per site were compared to land use patterns and sampling years, while their similarities were assessed using hierarchical cluster analysis. Overall, 24 CUPs were detected at least once. In 93% of all samples, at least one CUP was detected, while 78% of the samples had mixtures of two or more CUPs (median 3, interquartile range 5). Atrazine and chlorpyrifos were detected in 19 out of 20 sampling sites. Carbaryl, metazachlor, simazine, tebuconazole and terbuthylazine had the highest detection frequencies at sampling sites dominated by croplands. Across all the sampling years, 16 CUPs were present. Seven CUPs were newly detected from 2016 onwards (azinfos-methyl, dimetachlor, chlorsulfuron, chlortoluron, isoproturon, prochloraz and pyrazon), while metamitron was only present before 2012. Sites within a radius of about 200 km showed similarities in detected CUP mixtures across all samples. Our results show the presence of CUP mixtures across multiple agricultural and urban locations in Africa which requires further investigation of related environmental and human health risks.

Changes induced by atrazine in Clarias gariepinus provide insight into alterations in ovarian histoarchitecture and direct effects on oogenesis

Clarias gariepinus juveniles were exposed to environmentally relevant concentrations of 0 (control), 2.5, 25, 250 and 500 μg L^-1 atrazine in a quality-controlled 28-day laboratory procedure. Findings revealed a significant decrease in the levels of follicle-stimulating hormone, luteinizing hormone and prolactin relative to control (p < 0.05). Atrazine reduced the levels of testosterone while increasing the concentration of progesterone. Histologically, the control and treatments presented three stages of oocyte maturation: the chromatin nucleolar oocyte stage, early perinucleolar oocyte stage and the vitellogenic oocyte stage. However, in the ovaries of the treatment group with the lowest treatment concentration (2.5 μg L^-1), atretic oocytes with broken membranes invaded many of the dead ova and empty spaces. In other treatments (25, 250 and 500 μg L^-1), interfollicular spaces, vacuolation in oocyte formation, and dissolution of oocyte walls were observed. Disruption of the yolk vesicle and clumping of the cytoplasm in maturing oocytes was observed only at the highest atrazine concentration (500 μg L^-1). Gross alterations in ovarian histoarchitecture and reproductive hormone levels observed in this study showed interference with oogenesis which may result in reduced egg viability and fecundity in fish with ecological implications in water bodies exposed to atrazine even at reduced concentrations.

Comprehensive fitness evaluation of common carp (Cyprinus carpio L.) after twelve weeks of atrazine exposure

Atrazine is frequently detected in surface waters and negatively affect physiological function in aquatic organisms. Even though numerous authors have intensively studied its toxicity, only limited information concerning the long-term fish exposure is available. The aim of this study was evaluation of chronic exposure in common carp. Fish were exposed to a range of atrazine concentrations (0.3 - environmentally relevant concentration; 300; 1000; and 3000 µg/l) for twelve weeks. The potential impact of atrazine exposure was studied using various markers (behaviour; biometrical characteristics; haematological, biochemical and oxidative stress indices and histopathological changes). Most alterations were recorded at the highest concentration (3000 µg/l) which is probably due to a combined effect of both the herbicide exposure and intensive parasite infection development during second week. This group was cancelled after three weeks due to adverse health status, which partly confirmed atrazine immunotoxicity. Chronic exposure resulted in long-term reduction in feed intake followed by a significant decrease in body weight and morphological changes in gill at 1000 µg/l. At the same concentration, significant alterations in haematological (e.g. increase in erythrocyte, leukocyte, lymphocytes and neutrophil counts as well as decrease in monocyte counts) and biochemical (e.g. changes in enzyme activities; increase in glucose; decrease in ammonia) indices were documented, especially during first three weeks. Similar trend, but not so intensive, was observed at 300 µg/l. Moreover, significant changes were observed in various indicators of oxidative stress. These alterations were highly variable with both increasing and decreasing trends depending on dose and analysed tissue. Significant changes, especially in white blood profile, enzyme activities and oxidative stress indices, were proven even at 0.3 µg/l. Obtained results indicate that chronic atrazine exposure of common carp can negatively influence many indicators of health status such as behaviour, immune response, haematological and biochemical profile, oxidative stress indices and organ histopathology.

Distinct m6A methylome profiles in poly(A) RNA from Xenopus laevis testis and that treated with atrazine

Recent discovery of reversible N⁶-methyladenosine (m⁶A) methylation on messenger RNA (mRNA) and mapping of m⁶A methylomes in mammals, plant and yeast revealed potential regulatory functions of this RNA modification. However, the role of the m⁶A methylomes in amphibious is still poorly understood. Here, we examined the m⁶A transcriptome-wide profile in testis tissues of Xenopus laevis (X. laevis) with and without treatment with 100 μg/L atrazine (AZ) through m⁶A sequencing analysis using the latest Illumina HiSeq sequencer. The results revealed that m⁶A is a highly conserved modification of mRNA in X. laevis. Distinct from that in mammals, m⁶A in X. laevisis enriched around the stop codon and start codon, as is reported in plant. We then investigated the differential expression m⁶A in testes of AZ-exposed X. laevis and compared that with the X. laevis in the control group by m⁶A sequencing. The results indicated that AZ leads to altered expression profile in 1380 m⁶A modification sites (696 upregulated and 684 downregulated). KEGG pathway analysis indicates that the "NOD-like receptors", "tight junction", "Peroxisome proliferator-activated receptors", "adherens junctions", "Glycerophospholipid metabolism" and "Fatty acid biosynthesis" signaling pathways may be associated with abnormal testis development of X. laevis due to exposure to AZ. Analysis results showed a positive correlation between m⁶A modification and mRNA abundance, suggesting a regulatory role of m⁶A in amphibious gene expression. Our first report of m⁶A transcriptome-wide map of an amphibian species X. laevis presented here provides a starting roadmap for uncovering m⁶A functions that may affect/control amphibian testis development.

An overview of the potential impacts of atrazine in aquatic environments: Perspectives for tailored solutions based on nanotechnology

Atrazine is a pre- and post-emergence herbicide used to control weeds in many crops. It was introduced in the late 1950s, but its use has been controversial because of its high potential for environmental contamination. In agriculture, the implementation of sustainable practices can help in reducing the adverse effects atrazine. This review addresses aspects related to the impacts of atrazine in the environment, with focus on its effects on aquatic species, as well as the potential use of nanoencapsulation to decrease the impacts of atrazine. The application of atrazine leads to its dispersal beyond the immediate area, with possible contamination of soils, sediments, plantations, pastures, public supply reservoirs, groundwater, streams, lakes, rivers, seas, and even glaciers. In aquatic ecosystems, atrazine can alter the biota, consequently interfering in the food chains of many species, including benthic organisms. Nanoformulations loaded with atrazine have been developed as a way to reduce the adverse impacts of this herbicide in aquatic and terrestrial ecosystems. Ecotoxicological bioassays have shown that this nanoformulations can improve the targeted delivery of the active ingredient, resulting in decreased dosages to obtain the same effects as conventional formulations. However, more detailed analyses of the ecotoxicological potential of atrazine-based nanoherbicides need to be performed with representative species of different ecosystems.

Nuclear receptor AHR-mediated xenobiotic detoxification pathway involves in atrazine-induced nephrotoxicity in quail (Coturnix C. coturnix)

Atrazine (ATR), one of the most widely used pesticides in agricultural production, are gradually concerned due to potential ecosystem and health risks. Further, the induction of ATR nephrotoxicity and detoxification response is still unknown. To evaluate ATR-induced nephrotoxicity, quails were treated with 0, 50, 250 or 500 mg/kg ATR by gavage administration for 45 days. Histopathology indicated that ATR exposure caused renal tubular epithelial cell swelling and endoplasmic reticulum degeneration, suggesting that ATR exposure causes renal impairment even renal diseases. Notably, ATR interfered cytochrome P450 system (CYP450s) homeostasis by enhancing contents or activities of CYP450s (total CYP450, Cyt b5, AH, APND, NCR and ERND) and the expression of CYP450 isoforms (CYP1A, CYP1B, CYP2C and CYP3A). ATR triggered phase II detoxifying reaction, reflected by the elevated GSH level, GST activity and the up-regulation of GST isoforms (GSTa, GSTa3 and GSTt1) and GSH synthetase (GCLC). Moreover, ABC transporters were activated to expel ATR from the body by increasing expression of MRP1 and P-GP gene. Accompanying these alterations, the nuclear receptors (AHR, CAR and PXR) were activated by ATR in a dose-dependent manner. Analysis results of present study demonstrated that the induction of phase II detoxifying enzyme system and ABC transporters could be modulated by nuclear receptors response and CYP450s disturbance in low-dose ATR-treated quail. In conclusion, all data suggested that nuclear receptors AHR-mediated detoxification pathway was involved in ATR-induced nephrotoxicity. These results provided new evidence about the nephrotoxic effects of ATR on the response of biotransformation and detoxification system.

Comprehensive investigation of pesticides in Brazilian surface water by high resolution mass spectrometry screening and gas chromatography-mass spectrometry quantitative analysis

In this work, a comprehensive investigation on the occurrence of pesticides in the Paraná 3 hydrographic basin of Paraná State, Brazil, was made by application of wide-scope screening based on ultra-high performance liquid chromatography (LC) and gas chromatography (GC) both coupled to quadrupole time-of-flight mass spectrometry (QTOF MS). The use of two complementary techniques, such as GC-QTOF MS and LC-QTOF MS, allowed screening a large number of compounds with different polarity and volatility. This screening approach was applied to 17 samples, enabling the detection of fifty-two pesticides and six metabolites. In a second step, an specific research was made on the herbicide atrazine, one of the most frequent compounds in samples, and its major transformation products (TPs), which were quantitatively analyzed by dispersive liquid-liquid microextraction (DLLME) followed by GC-MS measurement. Twenty-one agricultural streams from the Paraná 3 hydrographic basin were sampled twice in 2017, each time along six successive weeks. Additional samples were also collected after rain events exceeding 10 mm. In total, 407 samples were quantitatively analyzed by DLLME/GC-MS. Atrazine concentrations did not exceed the maximum permitted concentration of 2 μg L^-1 according to Brazilian legislation, and only one surface water sample, collected after precipitation events, was slightly above this value (2.89 μg L^-1). The maximum concentrations for the TPs desethylatrazine and deisopropylatrazine were 0.80 and 1.22 μg L^-1, respectively. Based on the quantification results, a map was produced showing the occurrence of atrazine and its TPs in the area under study. This is the first time that the presence of agrochemicals is evaluated in the Paraná 3 hydrographic basin.

Interference with lactate metabolism by mmu-miR-320-3p via negatively regulating GLUT3 signaling in mouse Sertoli cells

Disruption of the nursery function in Sertoli cells (SCs) by reducing lactate production, a preferred energy substrate for developed germ cells (spermatocytes and spermatids), is tightly associated with spermatogenic failure such as SC-only syndrome (SCOS). However, whether this complicated pathogenesis is regulated by certain miRNAs at the post-transcriptional level remain fascinating but largely unknown. Here we show for the first time that mmu-miR-320-3p was exclusively expressed in murine SCs and this expression was significantly induced in busulphan-treated murine testis. The most efficient stimulatory germ cell types for the induction of apoptosis-elicited mmu-miR-320-3p expression were meiotic spermatocytes and haploid spermatids. Functionally, forced expression of the exogenous mmu-miR-320-3p in SCs compromises male fertility by causing oligozoospermia and defection of sperm mobility. Mechanistically, mmu-miR-320-3p negatively regulates lactate production of SCs by directly inhibiting glucose transporter 3 (GLUT3) expression. Thus, dysregulation of mmu-miR-320-3p/GLUT3 cascade and consequently of lactate deficiency may be a key molecular event contributing the germ cell loss by SC dysfunction. Future endeavor in the continuous investigation of this important circulating miRNA may shed novel insights into epigenetic regulation of SCs nursery function and the etiology of azoospermia, and offers novel therapeutic and prognostic targets for SCOS.