Tissue distribution, metabolism and hepatic tissue injury in Chinese lizards (Eremias argus) after a single oral administration of lambda-cyhalothrin

Negative effects on the adaptive strategies of the lizards (Eremias argus) under starvation after exposure to Glufosinate-ammonium

Herbicide exposure poses a higher risk to reptiles due to their frequent contact with soil. Besides, food restriction is also a common environmental pressure that can seriously affect the survival of reptiles. The adaptive strategies of reptiles in the face of emerging herbicide pollution and food shortage challenges are not yet known. Therefore, Eremias Argus (a kind of small reptile) was selected as the model to simulate the real scenario of food shortage in lizards, aiming to explore the comprehensive impact of glufosinate-ammonium (GLA: an emerging herbicide) and food restriction on lizards. The results revealed that lizards often regulate their physiological and biochemical activities through body thermal selection and tend to choose lower body temperature, reduce digestibility, and actively participate in fat energy mobilization to avoid oxidative damage in the state of hunger, finally in order to achieve homeostasis. However, herbicide GLA disrupted the lizards' efforts to resist the stress of food shortage and interfered with the normal thermoregulation and energy mobilization strategies of lizards facing starvation. The results of this study would improve our understanding of the impacts of Lizards under extreme stresses, help supplement reptile toxicology data and provide scientific basis for the risk assessment of herbicide GLA.

Absorption, distribution, metabolism, and elimination of epoxiconazole enantiomers in lizards (Eremias argus)

Epoxiconazole (EPX) is a world widely used chiral triazole fungicide in the agriculture field. The excessive application of this triazole may cause damage to lizards. However, limited information is known about the toxicokinetics of EPX on lizards. Our study aimed to investigate the enantioselective absorption, distribution, metabolism, and elimination (ADME) of EPX in lizards following low and high dose exposure (10 and 100 mg kg-1 bodyweitht (bw)). The results demonstrated that (+)-EPX was easier absorbed than (-)-EPX in lizard plasma. Both (+)-EPX and (-)-EPX were detected in the liver, gonad, kidney, skin, brain, and intestine, with (+)-EPX preferentially distributed in these tissues. The elimination of (-)-EPX was faster than that of (+)-EPX in lizard liver and kidney in the high dose groups. Chiral conversion was found between EPX enantiomers in lizard skin. Simultaneously, five metabolites including M2, M4, M10, M18 and M19 were detected in lizard liver and kidney after EPX enantiomers exposure. The relative concentrations of M2, M4, and M10 were higher in the liver and kidney of (-)-EPX groups than those produced from (+)-EPX groups. The metabolic enzymes CYP3A4 and SULT1A1 primarily mediated enantioselective metabolism of EPX. The conclusions drawn from this study significantly enhance our understanding of the enantioselective behaviors of chiral triazole fungicides in reptiles, offering essential guidance for assessing the risks associated with different enantiomers of triazole fungicides.

Ecophysiological responses of Liolaemus arambarensis juveniles to experimental temperature variations

Climate change increasingly influences the loss of biodiversity, especially in ectothermic organisms, which depend on environmental temperatures to obtain heat and regulate their life cycle. Studies that aim to understand the impact of temperature variation are important to better understand the possible impacts generated on the homeostasis of ectothermic organisms. Our objective was to characterize the responses of juvenile Liolaemus arambarensis lizards to abrupt changes in temperature, quantifying markers of body condition, intermediary and hormonal metabolism and oxidative balance. We collected 45 juvenile individuals of L. arambarensis (winter: 20 and summer: 25) in Barra do Ribeiro, Brazil. We transported the animals to the laboratory, where they were acclimatized for five days at a temperature of 20 °C, then divided and exposed to temperatures of 10 °C, 20 °C, 30 °C and 40 °C for 24 h. After exposure, the animals were euthanized and the brain, caudal muscle, thigh, and liver tissues were extracted for quantification of biomarkers of metabolism (glycogen and total proteins) and oxidative balance (acetylcholinesterase, superoxide dismutase, catalase, glutathione-S-transferase and lipoperoxidation) and plasma for corticosterone quantification. The results show that L. arambarensis is susceptible to sudden temperature variations, where higher temperatures caused greater activity of antioxidant enzymes, increased lipoperoxidation and higher plasma levels of corticosterone in animals eliminated in winter. The present study demonstrated that abrupt changes in temperature could significantly modify the homeostatic mechanisms of animals, which could lead to oxidative stress and a potential trade-off between survival and growth/reproduction. In this context, the organism mobilizes energy resources for survival, with possible damage to growth and reproduction. Demonstrate that a change in temperature can be a potential factor in extinction for a species given the profile of global climate change.

Oxidative stress and mitochondrial damage in lambda-cyhalothrin toxicity: A comprehensive review of antioxidant mechanisms

Lambda-cyhalothrin, also known as cyhalothrin, is an efficient, broad-spectrum, quick-acting pyrethroid insecticide and acaricide and the most powerful pyrethroid insecticide in the world. However, there is increasing evidence that lambda-cyhalothrin is closely related to a variety of toxicity drawbacks (hepatotoxicity, nephrotoxicity, neurotoxicity and reproductive toxicity, among others) in non-target organisms, and oxidative stress seems to be the main mechanism of toxicity. This manuscript reviews the oxidative and mitochondrial damage induced by lambda-cyhalothrin and the signalling pathways involved in this process, indicating that oxidative stress occupies an important position in lambda-cyhalothrin toxicity. The mechanism of antioxidants to alleviate the toxicity of lambda-cyhalothrin is also discussed. In addition, the metabolites of lambda-cyhalothrin and the major metabolic enzymes involved in metabolic reactions are summarized. This review article reveals a key mechanism of lambda-cyhalothrin toxicity-oxidative damage and suggests that the use of antioxidants seems to be an effective method for preventing toxicity.

Mutagenicity, hepatotoxicity, and neurotoxicity of glyphosate and fipronil commercial formulations in Amazon turtles neonates (Podocnemis expansa)

Pesticides are considered one of the main causes of the population decline of reptiles worldwide, with freshwater turtles being particularly susceptible to aquatic contamination. In this context, we investigated the potential mutagenic, hepatotoxic, and neurotoxic effects in neonates of Podocnemis expansa exposed to substrate contaminated with different concentrations of glyphosate and/or fipronil during embryonic development. Eggs collected from the natural environment were artificially incubated in sand moistened with pure water, water added with glyphosate Atar 48® at concentrations of 65 and 6500 μg/L (groups G1 and G2, respectively), water added with fipronil Regent® 800WG at 4 and 400 μg/L (groups F1 and F2, respectively) and, water added with the combination of 65 μg/L glyphosate and 4 μg/L fipronil or with 6500 μg/L glyphosate and 400 μg/L fipronil (groups GF1 and GF2, respectively). For mutagenicity analysis, we evaluated the frequency of micronuclei (MN) and other erythrocyte nuclear abnormalities (ENAs), while for evaluation of hepatotoxicity and neurotoxicity, livers and encephalon were analyzed for histopathological alterations. Exposure to pesticides, alone or in combination, increased the frequency of erythrocyte nuclear abnormalities, particularly blebbed nuclei, moved nuclei, and notched nuclei. Individuals exposed to fipronil exhibited congestion and inflammatory infiltrate in their liver tissue, while, in the encephalon, congestion, and necrosis were present. Our study confirms that the incubation of eggs in substrate polluted with glyphosate and fipronil causes histopathological damage and mutagenic alteration in P. expansa, highlighting the importance of using different biomarkers to evaluate the ecotoxicological effects of these pesticides, especially in oviparous animals.

Temperature-Dependent Bioaccumulation, Metabolism, and Hepatotoxicity of Flufiprole in Lizards (Eremias argus)

As a phenylpyrazole insecticide, flufiprole is an important substitute for fipronil in the agricultural field of China. However, its bioaccumulation and metabolism in terrestrial organisms especially in the lizards living in the agricultural area have rarely been investigated. As an ectothermic animal, lizards are also sensitive to temperature changes. Considering global warming, this study measured bioaccumulation, metabolism, and hepatotoxicity of flufiprole in the Chinese native lizard (Eremias argus) under different temperature stresses. Lizards exposed to flufiprole-contaminated soil adsorbed flufiprole through the skin and flufiprole was preferred to accumulate in lizard liver and brain. The oxidation product fipronil sulfone was the main metabolite of flufiprole in both lizard liver and human liver microsomes, which were mainly metabolized by lizard CYP3A19 or human CYP3A4. The fipronil sulfone concentration increased with increased temperature in lizard tissues. In addition, more serious oxidative damage was shown under higher temperature as the glutathione (GSH), malondialdehyde (MDA), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in lizards increased with increased temperature after flufiprole exposure. Flufiprole exposure also induced lizard liver lesions, and these lesions became more serious in the higher-temperature groups. This study provided new insights into the risk assessment of flufiprole in lizards under global warming.

Processes involved in biochemical response to pesticides by lizard Podarcis siculus (Rafinesque-Schmaltz, 1810) – A field study

Although reptiles are non-target organisms of pesticide applications, their ecological niche and trophic role suggest that the use of these compounds in agriculture can have toxicological effects on them. Our recent field study on Italian wall lizard Podarcis siculus in hazelnut orchards evidenced that the use of pesticides-mixtures, consisting of thiophanate-methyl (TM), tebuconazole (TEB), deltamethrin (DM), lambda-cyhalothrin (LCT), besides copper sulphate, induced an increase of the total antioxidant capacity toward hydroxyl radicals and caused DNA damage; however, it did not cause neurotoxicity, and did not induce the glutathione-S-transferases' activities. These results raised some questions which were answered in this study by carrying out analyses on 4 biomarkers and 5 chemical substances in the tissues of non-target organisms coming from treated fields: cytochrome P450, catalase, total glutathione, and malondialdehyde, TM, TEB, DM, LCT and Cu. Our results highlighted a partial accumulation of different chemicals, the involvement of two important mechanisms of defence, and some cellular damages after exposure to the considered pesticides. In details, 1) LCT and DM were not accumulated in lizard muscle, copper remained at basal levels, whereas TM and TEB were uptaken with a partial metabolization of TM; 2) the cytochrome P450 and the catalase were involved in lizard biochemical responses to pesticides-mixtures used for "conventional" farming treatment; 3) "conventional" treatment with pesticides caused damage to lipids, besides DNA, probably related to the excess of hydroxyl radicals.

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.

Enantioselective accumulation, elimination and metabolism of fenbuconazole in lizards (Eremias argus)

The enantioselective accumulation, elimination and metabolism of fenbuconazole in lizards were determined following a single-dose (25 mg/kg^bw) exposure to racemic or enantiomeric fenbuconazole. Accumulation of fenbuconazole was found in lizard fat with rac-form > enantiopure enantiomers. The enantiomer fractions (EFs) were higher than 0.5 in the blood, while EFs were less than 0.5 in the liver, brain, skin and stomach. There was conversion from (+)-fenbuconazole to (-)-fenbuconazole in lizard liver and conversion from (-)-fenbuconazole to (+)-fenbuconazole in lizard liver and blood. The results showed that enantioselective accumulation appeared in lizards, but the direction varied among blood and different tissues. The elimination half-lives (t_1/2) of (+)-fenbuconazole were higher than those of (-)-fenbuconazole in the blood and liver, suggesting that (-)-fenbuconazole eliminated faster than (+)-fenbuconazole in these tissues. In addition, both (+)-fenbuconazole and (-)-fenbuconazole eliminated faster in the liver and stomach exposed to racemate than those exposed to enantiopure enantiomers. On the contrary, the form of racemate decreased the elimination rate of fenbuconazole in lizard fat. Synergistic elimination may occur when two enantiomers coexisted in lizard liver and stomach, while the racemate produced antagonistic elimination in lizard fat. Simultaneously, three metabolites, RH-6467, RH-9029&RH-9030 and keto-mchlorophenol, were discovered in lizard liver. Only two metabolites, RH-6467 and RH-9029&RH-9030, were found in lizard blood. RH-9029&RH-9030 were the major metabolites. The discovered enantiomers of (+)-fenbuconazole metabolites were different from those of (-)-fenbuconazole. The findings of this study may provide a better understanding of the enantioselective behaviors of chiral triazole fungicides in reptiles.

Enantioselective disposition and metabolic products of isofenphos-methyl in rats and the hepatotoxic effects

Isofenphos-methyl (IFP), a chiral organophosphorus pesticide, is one of the main chemicals used to control underground insects and nematodes. Recently, the use of IFP on vegetables and fruits has been prohibited due to its high toxicity. In this study, we investigated the enantioselective distribution and metabolism of IFP and its metabolites, namely, isofenphos-methyl oxon (IFPO) and isocarbophos oxon (ICPO), in male Sprague Dawley (SD) rats. Forty eight hours (48 h) after exposure, ICPO was the main detectable compound in blood (up to 75%) and urine (up to 77%), and we found that (S)-ICPO was significantly more stable than (R)-ICPO (p < 0.05). Therefore, (S)-ICPO was proposed as a suitable candidate biomarker for the biomonitoring of IFP in human urine and blood. After 48 h exposure, 21.2-41.0%, 4.1-15.1%, and 8.6-18.7% of dosed IFP was detected in the liver of racemic, R and S enantiomer-exposed rats, respectively, and R-IFP and R-IFPO showed a faster degradation (p < 0.05). Our results showed that after one week of consecutive exposure to IFP, ICPO was accumulated in the liver of rats in both racemic and enantiopure groups (no difference between the groups, p > 0.05). We found that cytochrome P450 (CYP) (i.e. CYP2C11, CYP2D2 and CYP3A2 enzymes and carboxylesterases) is responsible for the enantioselective metabolism of IFP in liver. In addition, rats exposed to (S)-IFP exhibited hepatic lipid peroxidation, liver inflammation and hepatic fibrosis. This study provides useful information and a reference for the biomonitoring and risk assessment of IFP and organophosphorus pesticide exposure.

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.

Lizards as model organisms to evaluate environmental contamination and biomonitoring

Environmental contamination is reaching ever higher levels and affecting several animal populations, including humans. In this context, studies are being developed to monitor and evaluate this environmental problem using bioindicators organisms, in addition to testing the toxicity of contaminants in the laboratory. In this perspective, reptiles are ideal animals for these types of studies, considering that they are ectothermic and have a slower metabolism directly influencing their recovery power, and therefore, they are more sensitive to xenobiotic effects. Among reptiles, lizards are animals that adapt to various environmental conditions, even being found in areas with arid characteristics. Therefore, a literature review was conducted in this study regarding the use of lizards as models for ecotoxicological studies, including biomonitoring, carried out in the last 10 years, with the aim of evaluating them as bioindicators in Brazilian semi-arid region. Studies were found involving ten lizard families, among which the most investigated was Lacertidae. The studies were classified into two categories: organic contaminants (pesticides, petroleum by-products, and explosives) and inorganic contaminants (metals such as zinc, lead and aluminum, and radionuclides). Contaminants directly contributed to DNA damage and to increasing the frequency of micronuclei in exposed animals, histopathological effects, and oxidative stress. The performed analysis highlights the usefulness of lizards as environmental biomonitors. However, the response profile is dependent on the exposure level and route, in addition to the environmental scenario analyzed. Therefore, future studies aimed at evaluating environmental contaminants are required under exposure conditions more related to the environmental reality to be studied.

Myclobutanil accumulation, transcriptional alteration, and tissue injury in lizards (Eremias argus) treated with myclobutanil enantiomers

Enantioselective toxicokinetics, accumulation, and toxicity of myclobutanil were investigated by oral exposure of myclobutanil enantiomers to lizards. After a single oral administration, the absorption half-lives ( [Formula: see text] ) and elimination half-lives (t_1/2k) were in the range of 0.133-14.828 and 3.641-17.682 h, respectively. The absorption and elimination half-lives of (+)-myclobutanil showed no significant differences from those of (-)-myclobutanil in lizard blood, whereas preferential enrichment of (-)-enantiomer was observed in the liver, fat, skin, intestine, lung and kidney. In the bioaccumulation experiments, the residue of (-)-myclobutanil was detected in most tissues at 7, 14, and 28 days, while (+)-myclobutanil was found only in lizard skin, at a concentration lower than that of (-)-myclobutanil. Thus, (-)-myclobutanil was preferentially accumulated in lizards. The transcriptional responses of metabolic enzyme genes indicated that cytochrome P450 1a1 (cyp1a1), cyp2d3, cyp2d6, cyp3a4 and cyp3a7 played a crucial role in the metabolism of (+)-myclobutanil, whereas cyp1a1, cyp2d3, cyp2d6, cyp2c8, and cyp3a4 contributed to the metabolism of (-)-myclobutanil. The difference in metabolism pathways may be a reason for the enantioselectivity of myclobutanil in lizard. Myclobutanil also affected the expression of antioxidant enzyme genes, and the (+)-myclobutanil treatment might produce higher oxidative stress in lizard liver when compared with its antipode. Hepatic histopathological changes such as hepatocellular hypertrophy, nuclear pyknosis, vacuolation, and non-zonal macrovesicular lipid accumulation were observed in the liver of lizards for both (+)-myclobutanil and (-)-myclobutanil treatments. Thus, myclobutanil could affect lizard liver upon multiple exposure. The findings of this study provide specific insights into the enantioselective metabolism and toxicity of chiral triazole fungicides in lizards.

Comparative toxicokinetics and tissue distribution of prothioconazole and prothioconazole-desthio in Chinese lizards (Eremias argus) and transcriptional responses of metabolic-related genes

Prothioconazole (PTC) is a widely used triazolinthione fungicide with low toxicity and short residual period. However, its desulfurization metabolite, prothioconazole-desthio (PTC-d), is more persistent and has higher toxicity in terrestrial animals. In this study, the toxicokinetics (TK) and tissue distribution of PTC and PTC-d in Chinese lizards (Eremias argus) were measured following single oral dose (100 mg kg^-1 body weight) treatments. TK parameters indicated that PTC was more rapidly absorbed than PTC-d, as indicated by its shorter time to reach peak concentrations in most tissues. Furthermore, the relative bioavailability of PTC in lizards was lower than that of PTC-d. Compared with PTC, PTC-d preferentially accumulated in lizards, as reflected by longer half-life of PTC-d. During the distribution process, PTC-d generated in vivo was transported from other tissues and was deposited in the skin and tail, where PTC-d may be excreted by exuviation or tail detachment. Preferential enrichment of S-enantiomer of both PTC and PTC-d were observed in all tissues. Hepatic cytochrome P450 gene expression measurement revealed that cyp1a5 and cyp3a28 exhibited the strongest responses in both treatment groups. In addition, the opposite responses of cyp2k4 in different treatment groups may indicate that this enzyme caused differences in the rates of metabolism of the two chemicals. This study compared the TK profile of PTC and its desulfurization metabolite PTC-d in lizards and demonstrated that the desulfurization of PTC could increase its ecological risk due to the higher bioavailability and persistence of PTC-d.

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.

Enantioselective Distribution, Degradation, and Metabolite Formation of Myclobutanil and Transcriptional Responses of Metabolic-Related Genes in Rats

Myclobutanil (MT), a chiral fungicide, can be metabolized enantioselectively in organisms. In this work, the associated absorption, distribution, metabolism and transcriptional responses of MT in rats were determined following a single-dose (10 mg·kg^-1 body weight) exposure to rac-, (+)- or (-)-MT. The enantiomer fractions (EFs) were less than 0.5 with time in the liver, kidney, heart, lung, and testis, suggesting preferential enrichment of (-)-MT in these tissues. Furthermore, there was conversion of (+)-form to (-)-form in the liver and kidney after 6 h exposure to enantiopure (+)-MT. Enrichment and degradation of the two enantiomers differed between rac-MT and MT-enantiomers groups, suggesting that MT bioaccumulation is enantiomer-specific. Interestingly, the degradation half-life of MT in the liver with rac-MT treatment was shorter than that with both MT-enantiomer treatments. One reason may be that the gene expression levels of cytochrome P450 1a2 ( cyp1a2) and cyp3a2 genes in livers treated with rac-MT were the highest among the three exposure groups. In addition, a positive correlation between the expression of cyp2e1 and cyp3a2 genes and rac-MT concentration was found in livers exposed to rac-MT. Simultaneously, five chiral metabolites were detected, and the enantiomers of three metabolites, RH-9090, RH-9089, and M2, were separated. The detected enantiomers of (+)-MT metabolites were in complete contrast with those of (-)-MT metabolites. According to the results, a metabolic pathway of MT in male rats was proposed, which included the following five metabolites: RH-9089, RH-9090, RH-9090 Sulfate, M1, and M2. The possible metabolic enzymes were marked in the pathway. The findings of this study provide more specific insights into the enantioselective metabolic mechanism of chiral triazole fungicides.

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.

Tropidurus torquatus (Squamata: Tropiduridae) as a bioindicator of heavy metal (aluminum and zinc) pollution in Vila Velha, Brazil

Urbanization is responsible for numerous environmental changes including pollution. Information on the susceptibility of reptiles to environmental contaminants is relatively scarce. Tropidurus torquatus represents a potential bioindicator of heavy metal pollution. Levels of heavy metals in tissues from T. torquatus depend on bioavailability and vary among different populations. The aim of this study was to determine the heavy metal concentration in liver and fat tissue of T. torquatus from three distinct populations in the state of Espírito Santo, Brazil. The study areas included coastal rocky outcrops, dunes, and mountain rocky outcrops; each area had a different climate, vegetation, and level of anthropogenic influence. Fifty-one individuals were captured. Biometrics and sexes were determined, and stomach contents were identified. The tissue samples were digested with nitric acid and analyzed via inductively coupled plasma optical emission spectrometry (ICP-OES) for aluminum (Al), arsenic (As), barium (Ba), cadmium (Cd), chromium (Cr), copper (Cu), lithium (Li), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), strontium (Sr), titanium (Ti), vanadium (V), and zinc (Zn) contents. The concentration of zinc in Tropidurus torquatus was higher in liver than in fat tissue (432 ± 1380 mg kg^-1), and that of aluminum was higher in fat tissue (765 ± 1455 mg.kg^-1). The animals' diet may be related to heavy metal contamination. The study suggests that T. torquatus could be used for soil biomonitoring with liver as a bioindicator for aluminum contamination and fat tissue as a bioindicator for zinc contamination. Graphical abstract ᅟ.

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.

Tissue distribution and toxicity effects of myclobutanil enantiomers in lizards (Eremias argus)

In recent years, serious environmental pollution has caused a decrease in the abundance of many species worldwide. Reptiles are the most diverse group of terrestrial vertebrates. There are large amounts of toxicological data available regarding myclobutanil, but the adverse effects of myclobutanil on lizards has not been widely reported. In this study, treatment groups were orally administered a single-dose of myclobutanil (20mg/kg body weight (bw)). Subsequently, it was found that there were differences in myclobutanil levels between the different tissues and concentrations also changed with degradation time. The tissue concentrations of myclobutanil decreased in the order of: stomach > liver > lung > blood > testis > kidney > heart > brain. Based on our results, the liver and testis were considered to be the main target organs in lizards, indicating that the myclobutanil could induce potential hepatic and reproductive toxicity on lizards. Meanwhile, it was also demonstrated that the toxic effects of myclobutanil was different in different species, and the distribution of different pesticides in lizards were different.

The tissue distribution, metabolism and hepatotoxicity of benzoylurea pesticides in male Eremias argus after a single oral administration

Benzoylurea pesticides (BPUs) are widely used to control the locust, but the toxicokinetics and hepatotoxicity of BPUs in lizards have not been investigated. In this study, the tissue distribution, metabolism and liver toxicity of diflubenzuron and flufenoxuron were assessed in the Eremias argus following a single oral exposure. Diflubenzuron preferred to accumulate in the fat and brain (>1.0 mg kg^-1) and was rapidly eliminate in other tissues. In the liver, 4-chloroaniline was one of diflubenzuron metabolites, although with a concentration less than 0.05% of the accumulated diflubenzuron. No significant difference was observed in the liver histopathology between the control and diflubenzuron exposure group. The expressions of Cyp1a and Ahr gene which control the cell apoptosis were also equal to the control level. After flufenoxuron exposure, biomodal phenomenon was observed in the liver, skin, brain, gonad, kidney, heart and blood circulation was an important route for the flufenoxuron penetration. The concentrations of flufenoxuron in all tissues were greater than 1.0 mg kg^-1 at 168 h. The excretion of flufenoxuron in the faeces was 1.5 fold higher than diflubenzuron. The hepatocytes in the flufenoxuron treated group showed vacuolation of cytoplasm and decreased nucleus. In addition, the Cyp1a and Ahr genes were significantly up-regulated in the flufenoxuron exposure group. These results suggested that the higher hepatotoxicity of flufenoxuron may be attributed to the higher residual level in the lizard tissues and the Cyp1a and Ahr genes can serve as biomarkers to assess the liver toxicity.

The impact of land use intensity and associated pesticide applications on fitness and enzymatic activity in reptiles-A field study

Environmental pollution and habitat loss are described as underlying causes for population declines in reptiles and especially affect species in agricultural landscapes. Studies dealing with effects of pesticide exposure on reptiles are limited, mainly addressing the orders Testudines and Crocodylia, but largely neglecting the most diverse reptile order Squamata (lizards and snakes). As a consequence, information regarding effects on their organisms, as well as exposure probability and pesticide uptake in the Reptilia has to be considered rather uncharted. We here ask how pesticide applications affect a widely distributed, synanthropic squamate species in Europe. We studied the common wall lizard (Podarcis muralis) with regard to enzymatic biomarkers of pesticide exposure (Glutathione-S-Transferase, Glutathione Reductase, Acetylcholinesterase) and body condition. Lizards were sampled from wild populations, along an exposure gradient (three exposed sites with differing land use intensity and one reference site). Our results suggest both dermal and oral uptake of pesticide formulations, with the former being especially relevant during the first two days after a pesticide application. Enzymatic activity slightly differed between exposure gradients, while showing overall similar patterns. Body condition of lizards decreased with increasing pesticide exposure. Furthermore, gender distribution was particularly skewed in favor to males within exposed sample sites. Although reptiles are not target organisms of pesticide applications, many species do come into contact with them, and most probably suffer from dermal and oral uptake. Thus, we believe it is indispensable for reptiles to be integrated in risk assessments in order to improve conservation practice.

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

Flufenoxuron is a widely used pesticide to inhibit the synthesis of chitin during insect development and its effect on the growth of lizards has been little addressed. The hypothalamus-pituitary-thyroid (HPT) axis plays an important role on the development of lizards. In this study, the lizards at different development stages (proliferation and resting stages) were exposed to flufenoxuron for 21 days. The plasma thyroid hormone levels, thyroid gland histopathology and expression profiles of thyroid hormone receptors (trα, trβ), deiodinases (dio1, dio2), and transthyretin (ttr) genes were measured to evaluated the toxic effect of flufenoxuron on the HPT axis at different stages. The flufenoxuron exposure showed more seriously effect on the triiodothyronine (T3) level at resting phase than that at proliferation stage. The follicle epithelium cell height in the thyroid was only significantly increased when the exposed male lizards were at proliferation stage. The alteration of HPT axis-related genes expression was gender and tissue dependent after flufenoxuron treatment. The lizards exposed to flufenoxuron showed that the trα, trβ, dio1, dio2, and ttr genes in the female liver were more sensitive at the proliferation stage than that at the resting stage. In the male brain, the expressions of trα, trβ, dio1, and dio2 gene were significant decreased at proliferation stage while significant increased at resting stage after flufenoxuron exposure. Therefore, the thyroid endocrine system of lizards could be affected by the flufenoxuron exposure and the different development stage should also be considered when study the toxic effect of contaminants on the lizards.