Vinclozolin affects the interrenal system of the rare minnow (Gobiocypris rarus)

Effect of Pesticide Vinclozolin Toxicity Exposure on Cardiac Oxidative Stress and Myocardial Damage

(1) Background: Vinclozolin is a popular fungicide used in fruit, ornamental plants, and vegetable crops. It has recently been seen that prolonged exposure to VZN can cause human or animal health damage to various organs, but little is known to date about its cardiovascular effects. In this study, we addressed the chronic effects of VZN on the myocardium and the enzymes involved in the cardiovascular function. (2) Methods: The animals were divided into four groups: group 1 served as the control, group 2 received 1 mg/kg of VZN by gavage, group 3 received 30 mg/kg of VZN by gavage, and group 4 received 100 mg/kg of VZN by gavage, for 30 days. (3) Results: Results showed that 100 mg/kg VZN markedly increased the plasma concentration of cardiac markers (CK-MB, cTnT, ANP, BNP). Moreover, compared to the control group, VZN treatment decreased the activity of SOD, CAT, and GPx, and downregulated the mRNA expression levels of Nrf2. Furthermore, collagen deposition was amplified owing to 100 mg/kg VZN cardiotoxicity. This harmful effect was confirmed by a histological study using hematoxylin and eosin (H&E) and Masson's trichrome staining. (4) Conclusion: Overall, our results proved the cardiotoxicity caused by chronic exposure to VZN.

Effects of chronic exposure to the fungicide vinclozolin on gut microbiota community in an aquatic turtle

Environmental issues associated with the widespread use of agricultural chemicals are being seriously concerned. Of them, toxicological impacts of fungicides in aquatic organisms are often overlooked. Here, soft-shelled turtle (Pelodiscus sinensis) hatchlings were exposed to different concentrations of vinclozolin (0, 5, 50, 500 and 5000 μg/L) for 60 days to investigate the impact of fungicide exposure on their gut microbial composition and diversity. Vinclozolin exposure significantly affected the composition of the gut microbiota in hatchling turtles. Unexpectedly, gut bacterial diversity and richness of vinclozolin-exposed turtles (but not for the 5000 μg/L-exposed group) were relatively higher than control ones. At the phylum level, the abundance of Firmicutes was decreased, while that of Proteobacteria was increased in high-concentration groups. At the genus level, some bacterial genera including Cellulosilyticum, Romboutsia and Clostridium_sensu_stricto, were significantly changed after vinclozolin exposure; and some uniquely observed in high-concentration groups. Gene function predictions showed that genes related to amino acid metabolism were less abundant, while those related to energy metabolism more abundant in high-concentration groups. The prevalence of some pathogens inevitably affected gut health status of vinclozolin-exposed turtles. Such gut microbiota dysbiosis might be potentially linked with hepatic metabolite changes induced by vinclozolin exposure.

Functional and hepatic metabolite changes in aquatic turtle hatchlings exposed to the anti-androgenic fungicide vinclozolin

Many man-made chemicals that are released into water bodies in agricultural landscapes have been identified as endocrine disruptors and can cause serious impacts on the growth and survival of aquatic species living in these environments. However, very little attention has been paid to their toxicological effects in cultured non-fish species, such as aquatic turtles. We exposed hatchlings of the Chinese soft-shelled turtle (Pelodiscus sinensis) to different concentrations of vinclozolin (0, 5, 50 and 500 μg/L) for 60 days to assess physiological and metabolic impacts of this fungicide. Despite no death occurrence, hatchling turtles exposed to the highest concentration of vinclozolin consumed less food, grew more slowly (resulting in smaller body size after exposure) and performed more poorly in behavioral swimming tests than controls and turtles exposed to lower concentrations. Hepatic metabolite profiles acquired via liquid chromatography-mass spectrometry (LC-MS) revealed multiple metabolic perturbations related to amino acid, lipid, and fatty acid metabolism in animals exposed to environmentally relevant concentrations. Specifically, many critical metabolites involved in energy-related metabolic pathways (such as some intermediates in the tricarboxylic acid cycle, lactate, and some amino acids) were present in livers of hatchling turtles exposed vinclozolin, though at lower concentrations, reflecting energy metabolism dysregulation induced by exposure to this fungicide. Overall, our results suggest that the changes in growth and behavioral performances caused by chronic vinclozolin exposure may be associated with internal physiological and metabolic disorders mediated at the biochemical level.

Embryonic exposure to pentabromobenzene inhibited the inflation of posterior swim bladder in zebrafish larvae

The emerging flame retardants pentabromobenzene (PBB) has been frequently detected in recent years and may pose exposure risks to wild animals and human beings. In this study, the inflation of posterior swim bladder of zebrafish larvae was used as an endpoint to study the developmental toxicity and putative mechanisms associated with PBB toxicity. Our results showed that embryonic exposure to PBB could significantly inhibit the inflation of posterior swim bladders. Reduced T3 levels and transcriptional changes of crh and pomc were observed in PBB treated zebrafish larvae at 120 hpf. However, key regulators of thyroid and adrenocortical system involved in the synthesis (tsh), biological conversion (ugt1ab, dio2) and functional regulation (trα, trβ, gr) showed no significant changes. Further data revealed that prlra was the only gene that was altered among the detected genes at 96 h post fertilization (hpf). At 120 hpf, the morphology of swim bladder indicated deflation in treatments at 0.25 μM and higher. In addition, the mRNA levels of anxa5, prlra, prlrb, atp1b2 and slc12a10 were all significantly changed at 120 hpf. Taken together, we suppose that embryonic exposure to PBB inhibited the inflation of swim bladder in zebrafish probably via prlra mediated pathways. The observed changes of thyroid and adrenocortical parameters might be indirect effects evoked by PBB exposure. Overall, our results provide important data and indications for future toxicological study and risk assessment of the emerging flame retardants PBB.

Pentachlorophenol affected both reproductive and interrenal systems: In silico and in vivo evidence

The present study investigated the effects on reproductive and interrenal system by pentachlorophenol (PCP) using in silico and in vivo assays. Molecular docking results indicated interacting potency of PCP with steroid receptors (ERα, ERβ, AR, GR) but not Cytochrome P450 enzymes (CYPs). In the in vivo assay, sexually matured rare minnow (Gobiocypris rarus) was exposed to environmental relevant concentrations of PCP (0, 0.5, 5, 50 μg L^-1). In male fish, 14-d exposure caused up-regulation of mRNA levels of hepatic erα, erβ, ar, gr, vtg and gonadal erα, vtg, ar, dmrt1, providing evidence for agonistic activities for steroid receptors by PCP. The up-regulated mRNA of gnrh, crf, pomc in the brain also indicated feed-forward responses of the hypothalamic-pituitary-gonadal/interrenal (HPG/I) axis. However, at 28th d the feed-forward response of the HPG axis seemed eased back and the HPI axis showed negative feedback responses. Corresponding changes including increases of plasma steroid hormones, inhibition of spermatogenesis, and decreased RSI were observed in male fish upon 28-d exposure to PCP. In the females, a transition from feed-forward responses to negative feedbacks of the HPG/I axis was also indicated by the transcriptional profiles at 14th and 28th day. Corresponding changes including increased E2, T and decreased C levels, degenerated ovaries, and decreased GSI and RSI were also observed. Overall, we concluded that PCP could interfere with steroid receptors, evoke responses of HPG/I axis, and finally result in adverse effects on reproductive and interrenal system in rare minnow at environmental relevant concentrations.

Mechanistic study of chlordecone-induced endocrine disruption: Based on an adverse outcome pathway network

The adverse outcome pathway (AOP) framework could be helpful for chemical risk assessment and mechanistic research. The aim of the present study was to unravel the mechanism of chlordecone-induced endocrine disruption by illustrating the main molecular initiating event (MIE)/perturbations responsible for the observed effects. In silico simulations were performed to predict the MIE(s), and the results pointed to agonistic interaction with estrogen receptors (ERα, ERβ), androgen receptor (AR), cytochrome P450 (CYP19A) by chlordecone. In vivo endocrine disruptions were evaluated in rare minnow (Gobiocypris rarus) exposed to 0.01, 0.1, 1 and 10 μg L(-1) chlordecone from 2 h post-fertilization until sexually mature. In the females, increases of vitellogenin (vtg) mRNA levels in liver and gonad, plasma estradiol (E2), testosterone (T) and E2/T, and renalsomatic index confirmed the role of agonism of ER and CYP19A as MIEs, but the decreased gonadosomatic index, degenerated ovaries as well as the feed-forward response pointed to other potential but important MIEs and corresponding AOPs. In the males, increased E2/T ratio, increased testis vtg mRNA levels and occurrence of intersex confirmed the roles of agonism of ERα and CYP19A as main MIEs in chlordecone-induced endocrine disruptions. Our results also fetches out the limit of AOPs in predicting the adverse outcomes and explaining the mechanism of chemicals at present, thus reflected a critical need for expanding AOPs and AOP network before using it in chemical risk assessment.

Transcriptome profiling analysis of rare minnow (Gobiocypris rarus) gills after waterborne cadmium exposure

Rare minnow (Gobiocypris rarus) is a widely used experimental fish in risk assessments of aquatic pollutants in China. Cadmium (Cd) is one of the most toxic heavy metals in the world; however, few studies have used fish gills, a multi-functional organ. In this study, we characterized the differential expression of adult female rare minnow gills after sub-chronic waterborne Cd (75μg/L CdCl2) exposure for 35d. A total of 452 genes (209 up-regulated and 243 down-regulated) were identified by gene expression profiling using RNA-Seq before and after treatment. Of these differentially expressed genes, 75, 21, and 54 differentially expressed genes are related to ion transport, oxidation-reduction processes, and the immune response, respectively. The results of GO and KEGG enrichment analyses, together with the altered transcript levels of major histocompatibility complex (MHC) class I and class II molecules and the significant increases in the levels of serum tumor necrosis factor α (TNF-α), interleukin 1β (IL1β) and nuclear factor-κB (NF-κB), indicated a disruption of the immune system, particularly the induction of inflammation and autoimmunity. The significant down-regulation of coagulation factor XIII A1 polypeptide (F13A1), tripartite motif-containing protein 21 (TRIM21), and Golgi-associated plant pathogenesis-related protein (GAPr) during both acute (≤96h) and sub-chronic (35d) waterborne Cd exposure, as well as their dosage dependence, suggested that these three genes could be used as sensitive biomarkers for aquatic Cd risk assessment.

Morphological alterations in the freshwater rotifer Brachionus calyciflorus Pallas 1766 (Rotifera: Monogononta) caused by vinclozolin chronic exposure

Vinclozolin (VZ) is a dicarboximide fungicide widely used on fruits, vegetables and wines, effective against fungi plagues. In this study we characterized the effects of VZ using a 4-day reproductive chronic assay with the freshwater rotifer Brachionus calyciflorus. The assay included observations of several features of asexual and sexual reproduction. Our results indicate that VZ: (a) increased asexual and sexual reproduction, (b) caused severe abnormality in females and (c) these abnormalities were inherited by sexual and asexual reproduction. At 1.2 mg/L three abnormal females were found out of 457 total females (0.66 %). This low percentage is consistent and reproducible according to further analysis, where we increased the number of replicates and total females exposed to 1.2 mg/L of VZ, and found 18 abnormal females out of 2868 total females (0.63 % abnormality). Interestingly, abnormal females found at 5.6 mg/L VZ exposure, were able to show mating behavior. Our results suggest that VZ behaves as a strong endocrine disruptor whose effects show the characteristic inverted-U-shape exposure concentration response curve regarding the intrinsic population increase and the percentage of abnormalities as endpoints.

The stepwise behavioral responses: behavioral adjustment of the Chinese rare minnow (Gobiocypris rarus) in the exposure of carbamate pesticides

In order to illustrate the behavioral regulation in environmental stress, the behavioral responses of the Chinese rare minnow (Gobiocypris rarus) to arprocarb, carbofuran, and oxamyl were analyzed with an online monitoring system. The Self-Organizing Map (SOM) was used to define the patterns of the behavioral data obtained from treatments at concentrations of 0.1 toxic unit (TU), 1 TU, 2 TU, 5 TU, 10 TU, and 20 TU and a control. In certain cases, differences among the carbamate pesticides (CPs) tested were observed. The profiles of behavioral strength (BS) in SOM varied according to the concentration used. The time of the first significant decrease of the BS varied inversely with the CP concentrations. The results suggested that the behavioral regulation in the stepwise behavioral responses (SBR) was evident. The primary movement behaviors shown by the SBR model included no effect, stimulation, acclimation, adjustment (readjustment), and toxic effect, especially at the lower concentrations. However, higher stress (10 TU and 20 TU) might limit the function of the behavioral adjustment produced by the intrinsic response mechanisms. It was concluded that SBR, which were affected by both the concentration and the exposure time, could be used as a suitable indicator in the ecotoxicological risk assessment of CPs.

Toxicity of pesticide and fertilizer mixtures simulating corn production to eggs of snapping turtles (Chelydra serpentina)

Many reptiles oviposit in soils associated with agricultural landscapes. We evaluated the toxicity of a pesticide and fertilizer regime similar to those used in corn production in Ontario on the survivorship of exposed snapping turtle (Chelydra serpentina) eggs. The herbicides atrazine, dimethenamid, and glyphosate, the pyrethroid insecticide tefluthrin, and the fertilizer ammonia, were applied to clean soil, both as partial mixtures within chemical classes, as well as complete mixtures. Eggs were incubated in the soil in a garden plot in which these mixtures were applied at a typical field application rate, and higher rates. Otherwise, the eggs were unmanipulated and were subject to ambient temperature and weather conditions. Eggs were also exposed at male producing temperatures in the laboratory in covered bins in the same soil, where there was less opportunity for loss through volatilization or leaching. Egg mortality was 100% at 10× the typical field application rate of the complete mixture, both with and without tefluthrin. At typical field application rates, hatching success ranged between 91.7 and 95.8%. Eggs exposed only to herbicides were not negatively affected at any application rates. Although fertilizer treatments at typical field application rates did not affect eggs, mortality was remarkably higher at three times this rate, and 100% at higher rates. The frequency of deformities of hatchlings was elevated at the highest application rate of the insecticide tefluthrin. The majority of the toxicity of the mixture was not due to the herbicides or insecticide, but was due to the ammonia fertilizer. At typical field application rates, the chemical regime associated with corn production does not appear to have any detrimental impacts upon turtle egg development; however toxicity dramatically increases if this threshold is passed.