Endocrine disruption caused by oral administration of atrazine in European quail (Coturnix coturnix coturnix)

Pesticides exposure and compromised fitness in wild birds: Focusing on the reproductive endocrine disruption

Exposure of pesticides to wildlife species, especially on the aspect of endocrine disruption is of great concern. Wildlife species are more at risk to harmful exposures to the pesticides in their natural habitat through diet and several other means. Species at a higher tropic level in the food chain are more susceptible to the deleterious effects due to sequential biomagnifications of the pesticides/metabolites. Pesticides directly affect fitness of the species in the wild causing reproductive endocrine disruption impairing the hormones of the gonads and thyroid glands as reproduction is under the influence of cross regulations of these hormones. This review presents a comprehensive compilation of important literatures on the impact of the current use pesticides in disruption of both the hypothalamic-pituitary-gonadal and hypothalamic-pituitary-thyroid axes particularly in birds addressing impacts on the reproductive impairments and overall fitness. In addition to the epidemiological studies, laboratory investigations those provide supportive evidences of the probable mechanisms of disruption in the wild also have been incorporated in this review. To accurately predict the endocrine-disruption of the pesticides as well as to delineate the risk associated with potential cumulative effects, studies are to be more focused on the environmentally realistic exposure dose, mixture pesticide exposures and transgenerational effects. In addition, strategic screening/appropriate methodologies have to be developed to reveal the endocrine disruption potential of the contemporary use pesticides. Demand for adequate quantitative structure-activity relationships and insilico molecular docking studies for timely validation have been highlighted.

Heat detoxification of Jatropha cucas meal and its effect on productive and reproductive performance of quail

Jatropha is a large, multipurpose, drought-tolerant plant with many traits and great potential as a biofuel crop. It originates from Central America but is now distributed throughout the tropics, including Africa and Asia. The study determines whether the dietary inclusion of raw Jatropha cucas meal (RJM, 3.5%) had negative impacts on the reproductive and productive performances of male Japanese quail as well as whether these impacts could be mitigated by heating the jatropha meal at 100°C for 24 or 48 h (JH24 or JH48 respectively). One hundred twenty healthy mature male quails at the age of 12 wk were assigned randomly to 4 treatments. Every treatment had 6 replicates, with 5 birds per replicate. The RJM caused a considerable decline in fertility and a high mortality rate in quail, whereas heat-treated jatropha meal (JH24 or JH48) decreased these unwanted effects. The RJM significantly increased triglycerides, aspartate aminotransferase (AST), and alanine aminotransferase (ALT), while reducing total protein and albumin. These values returned to normal in the JH24 and JH48 groups. The RJM significantly reduced the testosterone and increased estradiol and hepatic content of vitellogenin (Vtg) and estrogen receptor alpha (ERα) while they were normal in JH48 group. Superoxide dismutase (SOD) and catalase (CAT) activities, and the reduced glutathione (GSH) content in testicular tissues were significantly reduced in the RJM group when compared to control. Protein carbonyl (PC), malondialdehyde (MDA), and 8-hydroxy 2 deoxyguanosine (8-OHdG) levels were significantly increased in the RJM group when compared to control. Heating of JM for 48 h reduced the 8-OHdG and MDA levels toward the control level better than JH24 and restored PC to normal. Based on the obtained results, The toxic components in JM could be eliminated through heat treatment, and extending the treatment duration to 48 h is recommended for transforming the potentially harmful jatropha meal into an alternative protein source for livestock nutrition.

Comprehensive analysis of differences of N6-methyladenosine of lncRNAs between atrazine-induced and normal Xenopus laevis testis

Background

Increasing evidence suggested N⁶-methyladenosine (m⁶A) modification is crucial for male germline development. However, m⁶A modification of lncRNAs gains a little attention in amphibians in recent years. Xenopus laevis (X. laevis) was chosen to be an ideal model organism for testing environmental endocrine disrupting chemicals (EDCs) exposure and resultant effects. Atrazine (AZ) as an endocrine disrupt can effect development of testis in amphibians. Our previous study revealed that m⁶A is a highly conserved modification across the species.

Results

The results of m⁶A sequences showed that m⁶A-methylated lncRNAs enriched in intergenic region in testes of X. laevis. We further examined the differential expression of lncRNAs m⁶A sites in testes of AZ-exposed and compared with that in animals from control group. The results indicated that up to 198 differentially methylated m⁶A sites were detected within 188 lncRNAs, in which 89 significantly up-methylated sites and 109 significantly down-methylated sites. Data from KEGG pathway analysis indicated that AZ-affected lncRNAs m⁶A sites were mainly involved in 10 pathways in which 3 mutual pathways were found in the result of differentially m⁶A-methylated mRNAs.

Conclusions

These findings suggested that differentially m⁶A-methylated lncRNAs and these 3 pathways may act on regulatory roles in abnormal testis development of AZ-exposed X. laevis. This study for the first time provides insights into the profile of lncRNAs m⁶A modifications in amphibian species.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41021-021-00223-0.

The impact of endocrine-disrupting chemical exposure in the mammalian hypothalamic-pituitary axis

The hypothalamic-pituitary axis (HP axis) plays a critical and integrative role in the endocrine system control to maintain homeostasis. The HP axis is responsible for the hormonal events necessary to regulate the thyroid, adrenal glands, gonads, somatic growth, among other functions. Endocrine-disrupting chemicals (EDCs) are a worldwide public health concern. There is growing evidence that exposure to EDCs such as bisphenol A (BPA), some phthalates, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and biphenyls (PBBs), dichlorodiphenyltrichloroethane (DDT), tributyltin (TBT), and atrazine (ATR), is associated with HP axis abnormalities. EDCs act on hormone receptors and their downstream signaling pathways and can interfere with hormone synthesis, metabolism, and actions. Because the HP axis function is particularly sensitive to endogenous hormonal changes, disruptions by EDCs can alter HP axis proper function, leading to important endocrine irregularities. Here, we review the evidence that EDCs could directly affect the mammalian HP axis function.

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.

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.

A Review on Recent Treatment Technology for Herbicide Atrazine in Contaminated Environment

Atrazine is a kind of triazine herbicide that is widely used for weed control due to its good weeding effect and low price. The study of atrazine removal from the environment is of great significance due to the stable structure, difficult degradation, long residence time in environment, and toxicity on the organism and human beings. Therefore, a number of processing technologies are developed and widely employed for atrazine degradation, such as adsorption, photochemical catalysis, biodegradation, etc. In this article, with our previous research work, the progresses of researches about the treatment technology of atrazine are systematically reviewed, which includes the four main aspects of physicochemical, chemical, biological, and material-microbial-integrated aspects. The advantages and disadvantages of various methods are summarized and the degradation mechanisms are also evaluated. Specially, recent advanced technologies, both plant-microbial remediation and the material-microbial-integrated method, have been highlighted on atrazine degradation. Among them, the plant-microbial remediation is based on the combined system of soil-plant-microbes, and the material-microbial-integrated method is based on the synergistic effect of materials and microorganisms. Additionally, future research needs to focus on the excellent removal effect and low environmental impact of functional materials, and the coordination processing of two or more technologies for atrazine removal is also highlighted.

Enhanced Photoelectrocatalytic Reduction and Removal of Atrazine: Effect of Co-Catalyst and Cathode Potential

Photoelectrocatalytic (PEC) reduction and removal of atrazine, one typical endocrine disruptor chemical, was achieved on Pd quantum dots modified TiO₂ nanotubes (PdQDs@TiO₂NTs) under regulating potentials. Compared with that on TiO₂NTs, the PEC reduction efficiency of atrazine on PdQDs@TiO₂NTs significantly increased, mainly attributed to the reduced electron transfer resistance, longer lifetime of the photogenerated electrons and the faster electron injection from the catalyst to atrazine in the solution. Meanwhile, PdQDs could also function as cocatalyst so that the electrocatalytic activity of PdQDs@TiO₂NTs was evidently improved. Moreover, the investigation indicated that the applied potential not only played important role in accelerating the separation of photogenerated electrons and holes, but also with the increment of the cathodic potential, the PEC reduction mechanism of atrazine underwent the variation of electro-assisted photocatalysis, synergetic photoelectro-catalysis, and photoassisted electro-catalysis. A highest atrazine PEC reduction efficiency was achieved as 99.5% on PdQDs@TiO₂NTs in about 5 h under the potential of -1.3 V vs. SCE, whereas the highest synergetic effect of photo- and electro- catalysis was achieved at a lower potential of -0.9 V vs. SCE.

A novel mechanism underlies atrazine toxicity in quails (Coturnix Coturnix coturnix): triggering ionic disorder via disruption of ATPases

The widely used atrazine has been reported to exhibit extensive ecological hazards. Due to the biological accumulation, atrazine elicits widespread toxic effects on different organisms. However, true proof for the mechanism of atrazine-induced toxicity is lacking. To determine the potential mechanism by which atrazine exerted toxic effects, quails were treated with atrazine (0, 50, 250 and 500 mg/kg) by gavage administration for 45 days. Atrazine significantly increased the histological alterations and serum creatine kinase, lactate dehydrogenase and choline esterase levels. A marked disorder in ionic (Na+, K+, Ca2+ and Mg2+)contents and the decrease of ATPases (Na+-K+-ATPase, Ca2+-ATPase, Mg2+-ATPase and Ca2+-Mg2+-ATPase) activities were observed in the heart and liver of atrazine-exposed quails. Of note, it was also observed that atrazine suppressed the transcription of Na+, K+ transfer associated genes (Na+-K+-ATPase subunits) and Ca2+ transfer associated genes (Ca2+-ATPase subunits, solute carriers) in heart and liver. In conclusion, atrazine induced cardiac and hepatic damage via causing the ionic disorder, triggering the transcription of the ion transporters and leading the histopathological and functional alternations in the heart and liver of quails. This study demonstrated atrazine significantly induced the ionic disorder via decreasing the ATPases activities and disturbing the transcription of the ion transporters.

Behavioral response and gene expression changes in fipronil-administered male Japanese quail (Coturnix japonica)

Fipronil is an important member of the phenylpyrazole group of insecticides and is widely used for various crops and vegetables to control insects, thereby exposing birds, animals, and humans to fipronil. Currently, there is limited information on the effects of fipronil exposure in Japanese quail. Therefore, our aim was to assess the reproductive toxicological effects of fipronil in the Japanese quail in a 15-day gavage study and then its recovery over a period of 60 days. Fipronil-administration led to significant losses in both feed intake and body weight. Whereas, the gonadosomatic index was not affected, and histological changes observed in the testes were reversible, particularly by day 45 and day 60 of recovery. Cloacal gland atrophy, reduced foam quantity and a reduction in fertility, sexual and aggressive behaviors, and serum testosterone with elevated estradiol (E2) hormone levels were also observed. All these changes gradually reversed during various recovery periods. Further, alterations in hepatic vitellogenin (Vtg) and estrogen receptor α (ERα) gene expression, assessed by quantitative polymerase chain reaction, were also observed. Specifically, ERα1 was induced after fipronil administration, while the Vtg transcript was elevated during both exposure and recovery periods. Our results showed that fipronil exposure has a profound negative influence on reproductive traits in the male Japanese quail and exhibits an estrogenic activity that can raise the incidence of infertility in males. Nevertheless, most of the changes could be reversed after a recovery period of 30-45 days.

Effects of Funnelliformis mosseae inoculation on alleviating atrazine damage in Canna indica L. var. flava Roxb

Atrazine residue in the environment continually damages plants and therefore requires immediate attention and effective development of methods for its decontamination. The effects of Funnelliformis mosseae inoculation on growth and physiology in atrazine-treated Canna indica L. var. flava Roxb. were investigated. At atrazine concentrations up to 15 mg L^-1, the growth of C. indica plants were negatively affected. Inoculation with F. mosseae alleviated the atrazine inhibition of plant growth and biomass. Furthermore, the chlorophyll content and root function increased under F. mosseae inoculation, and the oxidative stress of malondialdehyde, peroxidase, and superoxide dismutase activities induced by atrazine were also alleviated by F. mosseae inoculation. The removal rate of atrazine by untreated C. indica was significant, with removal rates of 20.5-55.3% by the end of a 14-day experiment; however, F. mosseae inoculation increased the removal rate to 35.6-75.1%. In conclusion, F. mosseae inoculation can alleviate the damage induced by atrazine in C. indica. Accordingly, C. indica inoculated with F. mosseae has excellent potential to be used in phytoremediation in habitats polluted by high atrazine concentrations.

Gene expression profiles in testis of developing male Xenopus laevis damaged by chronic exposure of atrazine

As a widely used herbicide, atrazine (AZ) has been extensively studied for its adverse effects on the reproductive system, especially feminization in male animals. However, the relationship of gene expression changes and associated toxicological endpoints remains unclear. In this study, developing Xenopus laevis tadpoles were exposed to concentration of AZ at 0.1, 1, 10 or 100 μg/L continuously. Compared with froglets in the control group, there were no significant differences in body length, body weight, liver weight and hepatosomatic index (HSI) of males in groups treated with AZ for 90 d. At 100 μg/L AZ treatment caused a significant reduction of gonad weight and gonadosomatic index (GSI) of males (p < 0.01). In addition, AZ at all dose levels caused testicular degeneration, especially in froglets from the groups with 0.1 and 100 μg/L which exhibited U-shaped dose-response trend. We further investigated the gene expression changes associated with the testicular degeneration induced by AZ. We found that the expression of 1165 genes was significantly altered with 616 upregulated and 549 downregulated compared to the expression profile of the control animals. KEGG analysis showed that genes which were significantly affected by AZ are mainly involved in arginine and proline metabolism, cell cycle, riboflavin metabolism, spliceosome, base excision repair and progesterone-mediated oocyte maturation pathway. Our results show that AZ may affect reproductive and immune systems by interference with the related gene expression changes during the male X. laevis development. The findings may help to clarify the feminization mechanisms of AZ in male X. laevis.

Intrinsic Clearance of Xenobiotic Chemicals by Liver Microsomes: Assessment of Trophic Magnification Potentials

The use of trophic magnification factors (TMFs) to characterize the bioaccumulation potentials of chemicals was encouraged; however, the method for the assessment of trophic magnification potentials is still lacking. We optimized the in vitro assays used for the measurement of intrinsic clearance in liver microsomes by incorporating benzo[a]pyrene (B(a)P) as a benchmark compound. The intrinsic clearance of 40 compounds was then measured in microsomes from fish (weevers) and birds (quail); the characteristics of the trophic transfer of these 40 compounds were previously investigated in an aquatic food web in Bohai in northern China. Chemicals that are biotransformed at a rate similar to or higher than that of B[a]P in the microsomes of both weevers and quail (in vitro intrinsic clearance values, CL; CL/CLB[a]P: 0.1 to 2.4) generally exhibited no significant trophic magnification or dilution in the food web (TMF ≈ 1 or < 1), whereas chemicals that are biotransformed at extremely slow rates compared with B[a]P (CL/CLB[a]P: 0 to 0.2) showed significant trophic magnification in the food web (TMF > 1). The in vitro intrinsic clearance values of the target chemicals were found to be consistent with their respective trophic transfer behavior in the aquatic food web. Significant negative correlations were also found between the TMFs and the intrinsic clearance values of all target chemicals obtained in microsomes from both weevers and quail. Multiple linear regression analysis showed that biotransformation rates (CL/CLB[a]P) are a more important factor compared with the lipophilicity of the chemicals (log Kow) in the assessment of the trophic magnification of chemicals in the aquatic food web.

Degradation of atrazine by UV/chlorine: Efficiency, influencing factors, and products

In this work, the degradation of atrazine by the combination of UV and chlorine (UV/chlorine) due to the formation of radicals during chlorine photolysis was systematically investigated in terms of efficiency, factors that influence the degradation kinetics, as well as oxidation products. It was found that the degradation efficiency of atrazine was enhanced by UV/chlorine compared to UV or chlorine alone. The degradation efficiency of atrazine was favorable at a lower pH, but was inhibited in the presence of natural organic matters. Meanwhile, the initial chlorine dosage, alkalinity, and chloride barely influenced the degradation efficiency under neutral pH conditions. The degradation of atrazine by UV/chlorine was inhibited in real waters (i.e., surface water and ground water) compared to in deionized water but was still more effective than UV alone. The oxidation products of atrazine resulting from de-alkylation, dechlorination-hydroxylation, alkylic-hydroxylation, alkylic-oxidation, alkylic-hydroxylation-dehydration, deamination-hydroxylation, and dechlorination-hydrogenation in UV/chlorine process were detected, which were slightly different from those formed in UV/H2O2 (commonly used UV-based advanced oxidation process). Particularly, the yields of three primary transformation products (desethyl-atrazine (DEA), desisopropyl-atrazine (DIA), and desethyl-desisopropyl-atrazine (DEIA)) were comparatively quantified in these two processes. The different trend of them formed in UV/chlorine system (DEA:DIA≈4) compared to that formed in UV/H2O2 system (DEA:DIA≈1) could be ascribed to the different reaction reactivities and mechanisms between HO• and Cl• with atrazine.

Atrazine triggers developmental abnormality of ovary and oviduct in quails (Coturnix Coturnix coturnix) via disruption of hypothalamo-pituitary-ovarian axis

There has been a gradual increase in production and consumption of atrazine (ATR) in agriculture to meet the population rising demands. Female reproduction is necessary for growth and maintenance of population. However, ATR impact on females and particularly ovarian developmental toxicity is less clear. The aim of this study was to define the pathways by which ATR exerted toxic effects on ovarian development of ovary and hypothalamo-pituitary-ovarian (HPO) axis. Female quails were dosed by oral gavage from sexual immaturity to maturity with 0, 50, 250 and 500 mg ATR/kg/d for 45 days. ATR had no effect on mortality but depressed feed intake and growth and influenced the biochemical parameters. Notably, the arrested development of ovaries and oviducts were observed in ATR-exposed quails. The circulating concentrations of E2, P, LH and PRL were unregulated and FSH and T was downregulated in ATR-treated quails. The mRNA expression of GnRH in hypothalamo and LH in pituitary and FSH in ovary was downregulated significantly by ATR exposure and FSH and PRL in pituitary were upregulated. ATR exposure upregulated the level of P450scc, P450arom, 3β-HSD and 17β-HSD in ovary and downregulated ERβ expression in female quails. However, ATR did not change ERα expression in ovary. This study provides new insights regarding female productive toxicology of ATR exposure. Ovary and oviduct in sexually maturing females were target organs of ATR-induced developmental toxicity. We propose that ATR-induced developmental abnormality of ovary and oviduct is associated with disruption of gonadal hormone balance and HPO axis in female quails.

Assessing atrazine-induced toxicities in Bufo bufo gargarizans Cantor

Atrazine (AZ), a widely used herbicide has drawn attentions for its potential impacts on amphibians. This study aims to investigate the toxicity of AZ in Bufo bufo gargarizans Cantor (B. bufo gargarizans), a species of toad commonly found in China and countries in East Asia. We treated tadpoles with 0.1, 1, 10 and 100 μg/L AZ for 85 days and examined related parameters. The results showed that the mortality of the toads in the treatment group increased dramatically in a U-shaped dose-response relationship. The hindlimb extension and metamorphosis rate of the toads were significantly inhibited by AZ at 10 and 100 μg/L. Under the same condition, there were significant progressive changes in the testicular structures. Moreover, we found that AZ has no significant effects on growth, sex ratios, gonadal morphology, forelimb emergence and histology in the ovaries. Our results support the idea that environmental contaminants including AZ may be relevant to global amphibian decline.

Chlorotriazines do not activate the aryl hydrocarbon receptor, the oestrogen receptor or the thyroid receptor in in vitro assays

Atrazine, prometryn, propazine and simazine are chlorotriazines that are commonly employed as herbicides. However, their use is a major cause of concern, due to their reported endocrine disrupting effects in different taxa. Data from studies on the molecular and cellular processes underlying the hormonal action of these substances are contradictory. The ability of these chlorotriazines and the atrazine metabolites, desethyl-s-chlorotriazine and desisopropyl-s-chlorotriazine, to trigger responses mediated by the oestrogen receptor (ER), aryl hydrocarbon receptor (AhR) and thyroid receptor (TR), was studied by using in vitro approaches. Transcriptional activation assays were applied to observe the activation of ER and TR. The induction of ethoxyresorufin-O-deethylase (EROD) activity in the RTG-2 cell line served as an indicator of AhR activation. No responses were found in any of the assays, with any of the six chlorotriazines tested. Our observations indicate that the chlorotriazines tested are unlikely to cause their endocrine effects via these receptors.