Unraveling the different toxic effect of flufenoxuron on the thyroid endocrine system of the Mongolia racerunner (Eremias Argus) at different stages

Sirtuin 3-mediated deacetylation of superoxide dismutase 2 ameliorates sodium fluoride-induced mitochondrial dysfunction in porcine oocytes

Fluoride exerts detrimental effects on germ cells and increases the infertility rate in women. Nevertheless, the precise mechanisms behind the developmental abnormalities caused by fluoride in oocytes remain poorly comprehended. The current study, we established mitochondrial damage model in oocytes via 50 μg/mL sodium fluoride (NaF) supplementation. We then examined the effects of honokiol in preventing mitochondrial deficits caused by NaF and investigated the mechanisms through which honokiol protects oocytes. The findings investigated that NaF increased levels of mitochondrial reactive oxygen species (mtROS) and hindered mitochondrial function, as evidenced by the dissipation of mitochondrial membrane potential, abnormal expression of mitochondrial DNA copy numbers, and mtDNA harm in oocytes. mtROS scavenging using Mito-TEMPO alleviated oxidative damage in mitochondria and restored the oocyte developmental competence. Superoxide dismutase 2 (SOD2) acetylation was significantly increased, whereas sirtuin 3 (SIRT3) expression was decreased in NaF-treated oocytes. The addition of honokiol helped in the deacetylation of SOD2 at K122 through SIRT3, resulting in the removal of excessive mtROS and the recovery of mitochondrial function. Therefore, SIRT3/SOD2 pathway aids honokiol in mitigating fluoride-induced mitochondrial dysfunction. Overall, honokiol improved the mitochondrial harm caused by NaF by controlling mtROS and mitochondrial function, with the SIRT3/SOD2 pathway having an important function. These findings suggest honokiol as a potential therapeutic strategy for NaF-induced oocyte development and mitochondrial deficits.

Application of machine learning to predict the inhibitory activity of organic chemicals on thyroid stimulating hormone receptor

With the promotion of carbon neutrality, it is also important to synchronously promote the assessment and sustainable management of chemicals so as to protect public health. Humans and animals are possibly exposed to endocrine disruptors that have inhibitory effects on thyroid stimulating hormone receptor (TSHR). As such, it is important to identify chemicals that inhibit TSHR and to develop models to predict their inhibitory activity. In this study, 5952 compounds derived from a cyclic adenosine monophosphate (cAMP) analysis, a key signaling pathway in thyrocytes, were used to establish a binary classification model comparing methods that included random forest (RF), extreme gradient boosting (XGB), and logistic regression (LR). The prediction model based on RF showed the highest identification accuracy for revealing chemicals that may inhibit TSHR. For the RF model, recall was calculated at 0.89, balance accuracy was 0.85, and its receiver operating characteristic (ROC) curve-area under (AUC) was 0.92, indicating that the model had very high predictive capacity. The lowest CDocker energy (CE) and CDocker interaction energy (CIE) for chemicals and TSHR were determined and were subsequently introduced into the predictive model as descriptors. A regression model, extreme gradient boosting-Regression (XGBR), was successfully established yielding an R² = 0.65 to predict inhibitory activity for active compounds. Parameters that included dissociation characteristics, molecular structure, and binding energy were all key factors in the predictive model. We demonstrate that QSAR models are useful approaches, not only for identifying chemicals that inhibit TSHR, but for predicting inhibitory activity of active compounds.

Toxicological effects of acute prothioconazole and prothioconazole-desthio administration on liver in male Chinese lizards (Eremias argus)

Prothioconazole (PTC) is a high effective systemic fungicide, and one of its major metabolites is prothioconazole-desthio (PTC-d). Because of its wildly use in the farmland of China, the local eco-toxicological effects of PTC as well as PTC-d are needed to be concerned. This study investigated hepatoxicity of Chinese lizards (Eremias argus), a local non-target organism, after single dose oral treated (100 mg kg^-1 BW) through pathological, enzyme activity and gene expression analysis. PTC treatment caused ballooning and PTC-d treatment led to macrovesicular steatosis of hepatocyte. The elevation of serum indexes, including the activities of aspartate aminotransferase (AST), alkaline phosphatase (ALP) and alanine aminotransferase (ALT), further confirmed the hepatic injury. PTC and PTC-d treatments altered oxidative status reflected by the inhibition of superoxide dismutase (SOD) activity , meanwhile, the stimulation of catalase (CAT) activity, glutathione peroxidase (GPx) activity and malondialdehyde (MDA) content. The mRNA expression changes of apoptosis-related factors and cytokines genes, including Bax, Bcl-2, TNF-α, NF-κB, Caspase-3 and Nrf2, deeply uncovered the potential mechanism of hepatotoxicity caused by PTC and PTC-d. In brief, the results indicated that both of these two compounds altered oxidative status, then were likely to trigger caspase-3 by affecting the ratio of pro- and anti-apoptotic factors which belong to intrinsic apoptosis pathway. Specifically, more serious impacts were induced by PTC-d than its parent compound. This study is the first to provide specific insight into potential hepatotoxicity resulted from PTC and PTC-d in male Chinese lizards.

Lambda-cyhalothrin and its common metabolite differentially modulate thyroid disruption effects in Chinese lizards (Eremias argus)

Although the thyroid effects of pyrethroids on non-target organisms have been well studied, research on the toxic effects of pyrethorid metabolites is still limited. In this study, a type of representative Chinese lizards was used as the model and exposed to environmentally relevant concentrations of lambda-cyhalothrin (LCT) and 3-phenoxybenzoic acid (PBA) through cultivation on 3 and 15 μg/g soil to evaluate and compare their disruption effects on lizard hypothalamus-pituitary-thyroid (HPT) axis. The alterations occurred in lizards were examined through histopathology analyses, hormone level and gene expression measurements, the molecular binding interactions were analyzed in silico as well. The results showed that LCT exposure increased the plasma triiodothyronine (T3), thyroxine (T4) levels and the follicular epithelium heights of thyroid glands, whereas PBA induced no or much less degree of alterations. The ugt and dio2 gene expression in lizard liver was significantly up-regulated by LCT, but PBA caused less or opposite effects. The in silico homology simulation illustrated that LCT binds to TRα in the similar way of T3, while PBA binds to TRβ in the same manner of T3. The results demonstrated that both LCT and its metabolite-PBA could disrupt lizard HPT axis but through distinct mechanisms. The information would facilitate the comprehensive environmental safety assessment of pyrethroids.

Flufenoxuron disturbs early pregnancy in pigs via induction of cell death with ER-mitochondrial dysfunction

The use of pesticides can result in unintended side effects, such as environmental pollution and animal diseases; in serious cases, it may cause abortion. Flufenoxuron is an inhibitor of chitin synthesis that is used widely as a pesticide on farmland. It is difficult to break down and therefore accumulates in the body, and has also been detected in breast milk. Moreover, the effects of flufenoxuron in pregnancy remain elusive. Therefore, we investigated the effects of flufenoxuron on early pregnancy. Our results suggested that flufenoxuron inhibits cell development and cell cycle progression in porcine trophectoderm (pTr) cell and porcine endometrial luminal epithelial (pLE) cell lines through the repression of signal transduction pathways. Flufenoxuron induced programmed cell death through DNA fragmentation and apoptotic signals. In addition, flufenoxuron induced ROS production, ER stress, and mitochondrial malfunction; consequently, the cytosolic and mitochondrial calcium levels were increased. Expression of proteins on the ER-mitochondrial axis was increased by flufenoxuron. Cell migration was decreased by flufenoxuron treatment between pLE and pTr cells. In addition, the expression of pregnancy-related genes was decreased flufenoxuron. Collectively, our results indicated that flufenoxuron may be harmful to livestock and women in the early stages of pregnancy.

Environmental relevant concentration of λ-cyhalothrin and 3-phenoxybenzoic acid caused endocrine-disrupting effects on male lizards (Eremias argus)

In the present study, the endocrine toxicity of LCT and PBA was investigated through exposure to Eremias argus for two weeks under environmental relevant concentration. RNA-sequencing identified 4442 and 4653 differentially expressed genes in lizard liver after LCT and PBA exposure. Four differentially expressed genes (hsd17β, ar, sult, ugt) related with hypothalamic-pituitary-gonadal axis were quantified by qPCR. The expression of genes associated with HPG axis in different tissues differed significantly. In LCT treatment group, ar, cyp17 and hsd3β genes involved in testosterone synthesis and transportation were significantly decreased in lizard testes, and the spermatogensis was inhibited in the testes, which indicated the anti-androgenic activity of LCT. After PBA exposure, the genes related with estradiol synthesis, transportation and metabolism, such as hsd17β, erα, ugt in lizard liver were important biomarkers and the significant decrease of estradiol level was highly correlated with hsd17β, erα, ugt gene expressions. The relative high binding affinity of PBA with ERα further demonstrated the anti-estrogenic activity of PBA. Our results elucidate the different toxic mechanism of LCT and PBA on lizard endocrine system at environmental relevant concentration. Pyrethroids metabolism may cause more seriously toxicity rather than detoxification.

Photosynthesis Inhibiting Effects of Pesticides on Sweet Pepper Leaves

Although a large number of pesticides of different compositions are regularly used in agriculture, the impact of pesticides on the physiology of field crops is not well understood. Pesticides can produce negative effects on crop physiology―especially on photosynthesis―leading to a potential decrease in both the growth and the yield of crops. To investigate these potential effects in greenhouse sweet peppers, the effect of 20 insecticides and 2 fungicides (each sprayed with a wetting agent) on the photosynthesis of sweet pepper leaves was analyzed. Among these pesticides, nine caused significant reductions in photosynthetic activity. The effects were observed in distinctive ways—either as a transitory drop of the photosynthetic-rate values, which was observed at two hours after the treatment and was found to have recovered after 24 h, or as a sustained reduction of these values, which remained substantial over a number of days. The results of this study suggest that the production of a crop may substantially benefit when the frequent use of pesticides can be substituted with alternative pest control methods (e.g., biological control). Our results advocate further investigation of the potential impact of pesticides, either alone or in combination, on the photosynthesis of crop plants.

Toxicity of pesticides in lizards

Many threats exist to reptile populations, environmental pollutants being one of them. Lizards and other reptiles are usually not taken into consideration in environmental risk assessments, with the use of surrogate species for their estimates. Unfortunately, not all pesticides have the same effects in the reptile species and on these surrogates, birds and mammals, some being more toxic in lizards. This difference brings the need to evaluate their toxicity in lizards to safeguard its protection. Studies in the last decades involving contaminants’ toxicity in lizard species have increased, thus we proposed to gather these information in this comprehensive review. Through searches in databases about the toxicity of pesticides in lizards, 16 scientific articles were found. Most studies investigated locomotor performance, histopathology, oxidative stress, neurotoxicology, and genetic damage from diverse pesticides with different modes of action. Progress has been made to acquire data on lizard ecotoxicology and more research is needed to cover more variables, such as studies in the embryologic stage and different pesticides.

Dose-dependent effects of flufenoxuron on thyroid system of mature female lizards (Eremias argus) and their offspring

More and more studies are focusing on toxic effect of pesticides on lizards. However, the responses of different life-stage lizards to pesticides have not been reported. In this study, according to RNA-seq library data, thyroxine 5'-deiodinase activity showed significant difference between mature and immature lizard liver. In addition, triiodothyronine (T3) level in immature lizard serum was higher than that in mature lizard serum. Thus, we investigated the thyroid disruption of flufenoxuron with different concentrations (0, 5, 20 mg/kg) to both mature lizards and their offspring. No significant differences were observed in immature lizard body weight compared between control and exposure groups while the body weight of mature lizards was significantly decreased after flufenoxuron exposure. Moreover, the levels of thyroid hormones and the expression of thyroid related genes changed with exposure concentration of flufenoxuron and exhibited different regulation mechanism between mature and immature lizards. In immature lizard liver, trα, trβ, dio1 and ugt genes controlled the thyroid hormone levels interfered by flufenoxuron. In contrast, the thyroxine (T4) pathway in mature lizard liver was significantly disrupted especially by 20 mg/kg flufenoxuron exposure. This study elucidated the different thyroid disruption effects of flufenoxuron to lizards based on different exposure doses and lizard life stages.

Enantioselective Elimination and Gonadal Disruption of Lambda-Cyhalothrin on Lizards ( Eremias argus)

In this study, the different metabolic pathways of lambda-cyhalothrin (LCT) enantiomers in Eremias argus feces and enantioselective disruption on hypothalamus-pituitary-gonad (HPG) system were investigated. After 7 days oral exposure to LCT enantiomers, the concentration of 3-phenoxybenzoic acid (PBA), hydroxylated and sulfated LCT were higher in the (+)-LCT exposure group than that in the (-)-LCT exposure group, which indicated a higher metabolic rate of (+)-LCT than (-)-LCT. Although no significant differences were seen on lizard body weight after enantiomers' exposure, the gonadosomatic index was dramatically decreased. The testicular impacts such as increased seminiferous tubule diameters were only observed in the (+)-LCT exposure group. Consistent with this result, the expression of ar gene in the (+)-LCT exposure was significantly higher than that in the (-)-LCT exposure group. In addition, the stronger binding affinity of AR with (+)-LCT further demonstrated the more serious disruption of (+)-LCT on lizard HPG axis than (-)-LCT. This study first elucidated the metabolic pathway and endocrine effects of LCT in lizards at enantiomeric level and provided some evidence for lizard population decline.

The body burden and thyroid disruption in lizards (Eremias argus) living in benzoylurea pesticides-contaminated soil

Dermal exposure is regarded as a potentially significant but understudied route for pesticides uptake in terrestrial reptiles. In this study, a native Chinese lizard was exposed to control, diflubenzuron or flufenoxuron contaminated soil (1.5 mg kg^-1) for 35 days. Tissue distribution, liver lesions, thyroid hormone levels and transcription of most target genes were examined. The half-lives of diflubenzuron and flufenoxuron in the soil were 118.9 and 231.8 days, respectively. The accumulation of flufenoxuron in the liver, brain, kidney, heart, plasma and skin (1.4-35.4 mg kg^-1) were higher than that of diflubenzuron (0-1.7 mg kg^-1) at all time points. The skin permeability factor of flufenoxuron was more than 20-fold greater than that of diflubenzuron at the end of exposure. However, the liver was more vulnerable in the diflubenzuron exposure group. The alterations of triiodothyronine (T3) and thyroxine (T4) level after diflubenzuron or flufenoxuron exposure were accompanied with the changes in the transcription of target genes involved not only in hypothalamus-pituitary-thyroid (HPT) axis (sult, dio2, trα and udp) but also in metabolism system (cyp1a and ahr). These results indicated that flufenoxuron produced greater body burdens to lizards through dermal exposure, whereas both diflubenzuron and flufenoxuron have the potential to disturb metabolism and thyroid endocrine system.

Stereoselective degradation and thyroid endocrine disruption of lambda-cyhalothrin in lizards (Eremias argus) following oral exposure

The disturbance of the thyroid system and elimination of chiral pyrethroid pesticides with respect to enantioselectivity in reptiles have so far received limited attention by research. In this study, bioaccumulation, thyroid gland lesions, thyroid hormone levels, and hypothalamus-pituitary-thyroid axis-related gene expression in male Eremias argus were investigated after three weeks oral administration of lambda-cyhalothrin (LCT) enantiomers. In the lizard liver, the concentration of LCT was negatively correlated with the metabolite-3-phenoxybenzoic acid (PBA) level during 21 days of exposure. (+)-LCT exposure induced a higher thyroid follicular epithelium height than (-)-LCT exposure. The thyroxine levels were increased in both treated groups while only (+)-LCT exposure induced a significant change in the triiodothyronine (T3) level. In addition, the expressions of hypothalamus-pituitary-thyroid axis-related genes including thyroid hormone receptors (trs), deiodinases (dios), uridinediphosphate glucuronosyltransferase (udp), and sulfotransferase (sult) were up-regulated after exposure to the two enantiomers. (+)-LCT treatment resulted in higher expression of trs and (-)-LCT exposure led to greater stimulation of dios in the liver, which indicated PBA-induced antagonism on thyroid hormone receptors and LCT-induced disruption of thyroxine (T4) deiodination. The results suggest the (-)-LCT exposure causes higher residual level in lizard liver while induces less disruption on lizard thyroid activity than (+)-LCT.

Oral and dermal diflubenzuron exposure causes a hypothalamic-pituitary-thyroid (HPT) axis disturbance in the Mongolian racerunner (Eremias argus)

Diflubenzuron (DFB) is a potential endocrine-disrupting chemical. However, its thyroid endocrine effect on reptiles has not been reported. In this study, immature lizards (Eremias argus) were exposed to 20 mg kg^-1 DFB once a week for 42 days through oral or dermal routes. Their body weight, plasma thyroid hormone levels, thyroid gland histology and the transcription of hypothalamic-pituitary-thyroid (HPT) axis-related genes in different tissues were assessed to explore the effects of DFB on the HPT axis of lizards. The body weight decreased significantly only after the dermal exposure to DFB. Triiodothyronine (T3) to thyroxine (T4) ratio in the male plasma also significantly increased after the dermal exposure. After oral exposure, the activity of thyroid gland was positively related to the thyroid hormone levels. Furthermore, the alterations in thyroid hormone levels affected the HPT axis-related gene expression, which was tissue dependent and sexually selected. The thyroid hormone receptor genes (trα and trβ) in the brain and thyroid were more sensitive to oral exposure. However, only the dermal treatment affected the trα, trβ and type 2 deiodinase (dio2) genes in the male liver. These results suggest that DFB exposure caused sex-specific changes in the thyroid function of lizards, and the dermal treatment may be an important route for the risk assessment of reptiles.