Bisphenol A Induces a Distinct Transcriptome Profile in the Male Fish of the Marine Medaka Oryzias javanicus

Negligible additive effect of environmental concentrations of fragmented polyethylene terephthalate microplastics on the growth and reproductive performance of Java medaka exposed to 17β-estradiol and bisphenol A

To investigate whether environmental concentrations of fragmented polyethylene terephthalate (PET) microplastics (MPs) have additional or combined effects on endocrine-disrupting activity, Java medaka (Oryzias javanicus) were exposed to 17β-estradiol (E2; 5, 10, 50, and 100 ng L-1), bisphenol A (BPA; 5, 10, 50, and 100 µg L-1), and E2 and BPA combined with PET MPs (1 and 100 particles L-1) for 200 days. The growth parameters, such as body length and weight, were significantly decreased by the highest concentrations of E2 and BPA. A significant reduction in egg production was observed in female fish exposed to BPA, with an additive toxic effect of PET MPs. A female-biased sex ratio was observed in fish exposed to both chemicals. Exposure to E2 significantly increased the hepatosomatic index (HSI) in both sexes, while no significant effect was observed in the gonadosomatic index (GSI). Exposure to BPA significantly increased the HSI in female fish and decreased the GSI in both sexes of fish. An additive effect of PET MPs was observed on the GSI value of female exposed to BPA. Significant elevations in vitellogenin (VTG) levels were observed in both sexes due to exposure to E2 and BPA. Additive effects of PET MPs were observed on VTG levels in males exposed to E2 and BPA. Taken together, even long-term treatment with PET MPs induced only a negligible additive effect on the endocrine-disrupting activity in Java medaka at environmentally relevant concentrations.

Effects of primary leachates of conventional and alternative plastics in Cyprinodon variegatus fish larvae: Endocrine disruption and toxicological responses

The inclusion of hazardous substances in the formulation of plastics raises significant concerns, particularly, if those substances are released as primary leachates during plastic degradation and/or fragmentation. In this sense, the production of degradable plastics holding deleterious additives can increase the release of harmful substances into the environment. Additionally, the effects of primary leachates of "eco-friendly" materials remain unexplored. To address this, we performed exposures to primary leachates of alternative polymers, and commercial bags to verify possible responses associated with endocrine disruption and/or activation of the detoxification pathway in larvae of the marine fish model Cyprinodon variegatus. The chemical characterization evidenced a great number of additives in the formulation of the materials analyzed in this study. Those include, except for the PLA sample, relevant levels of the hazardous phthalates DEHP and DiBP. Regarding the effects on marine fish larvae, exposure to leachates from alternative polymers (10 g/L) PHB and PHBV produced remarkable mortality (100%). While the exposure to bag leachates of all tested materials (1 and 10 g/L) produced alterations in biomarkers for steroidogenic and detoxification pathways. To a lesser extent (10 g/L), three materials produced significant alterations in estrogenic biomarkers (Home-compostable bag 1, LDPE and Recycled PE bags). Although the alterations in gene expression were not directly correlated to the amount of DEHP or DiBP, we can conclude that primary leachates of "eco-friendly" bags are harmful to marine vertebrates.

Obesity III: Obesogen assays: Limitations, strengths, and new directions

There is increasing evidence of a role for environmental contaminants in disrupting metabolic health in both humans and animals. Despite a growing need for well-understood models for evaluating adipogenic and potential obesogenic contaminants, there has been a reliance on decades-old in vitro models that have not been appropriately managed by cell line providers. There has been a quick rise in available in vitro models in the last ten years, including commercial availability of human mesenchymal stem cell and preadipocyte models; these models require more comprehensive validation but demonstrate real promise in improved translation to human metabolic health. There is also progress in developing three-dimensional and co-culture techniques that allow for the interrogation of a more physiologically relevant state. While diverse rodent models exist for evaluating putative obesogenic and/or adipogenic chemicals in a physiologically relevant context, increasing capabilities have been identified for alternative model organisms such as Drosophila, C. elegans, zebrafish, and medaka in metabolic health testing. These models have several appreciable advantages, including most notably their size, rapid development, large brood sizes, and ease of high-resolution lipid accumulation imaging throughout the organisms. They are anticipated to expand the capabilities of metabolic health research, particularly when coupled with emerging obesogen evaluation techniques as described herein.

Bisphenol A disturbs hepatic apolipoprotein A1 expression and cholesterol metabolism in rare minnow Gobiocypris rarus

Bisphenol A (BPA) is a well-known plasticizer, which is widely distributed in the aquatic environment. Lots of studies showed that BPA could lead to lipid metabolism disorder in fish, but few studies studied the mechanism from the perspective of lipid transport. Apolipoprotein A1 (ApoA1) is the main component of high-density lipoprotein (HDL), and plays important roles in reverse cholesterol transport (RCT). In this study, we investigated the effect and molecular mechanism of BPA on ApoA1 and its effect on cholesterol in adult male rare minnow. Results showed that BPA could disturb hepatic ApoA1 expression through regulating Esrrg recruitment and DNA methylation in its promoter region, and ultimately up-regulated ApoA1 protein levels. The increased hepatic ApoA1 improved HDL-C levels, enhanced RCT, and disrupted cholesterol levels. The present study reveals the effect and mechanism of BPA on fish cholesterol metabolism from the perspective of cholesterol transport.

Bisphenol A induces hepatic triglyceride level in adult male rare minnow Gobiocypris rarus

Bisphenol A (BPA), an endocrine disruptor, exist in almost all waters. In the present study, we expose adult male Gobiocypris rarus rare minnow to 15 μg/L BPA to study the effect BPA on fish hepatic lipid metabolism. Following 1, 3 and 5 weeks exposure, the liver tissue of rare minnow was separated. The change of the hepatic morphology, hepatosomatic index, lipid composition and expression of lipid metabolism related genes were analyzed through paraffin section, oil red O staining, lipidomic analysis, and quantitative real-time PCR. BPA can cause significant hepatic lipid deposition in male rare minnow, leading to an increase in triglyceride (TG) level (1.84-22.87-fold), but it is also accompanied by a decrease in diglyceride level (1.67-4.78-fold). The expression of lipid metabolism related genes showed that BPA exposure can up-regulate TG synthesis related genes expression, and down-regulate TG degradation genes expression. Expression of TG transport related genes were also disrupted by BPA. It suggests that BPA can up-regulate rare minnow hepatic TG level through multi-path, and ultimately lead to lipid accumulation in the liver. The results of the present study enrich the mechanisms of environmental endocrine disruptors affecting lipid accumulation in fish.

Acute toxicity of Bisphenol A (BPA) to tropical marine and estuarine species from different trophic groups

BPA is chemical pollutant of very high concern due to its toxicity to the environment and risks for human health. Environmental concern consists in BPA entrance into aquatic ecosystems due to acute and chronic toxicity to invertebrates and vertebrates. This study aimed to determine acute BPA toxicity to tropical estuarine-marine species of four trophic levels and integrate BPA toxicity values using species sensitivity distribution (SSD) analysis. Our hypothesis is that BPA toxicity increases towards higher trophic levels. Microalga (Tetraselmis sp.), zooplanktonic grazer (Artemia salina), deposit-feeder invertebrate (Heleobia australis), and omnivorous fish (Poecilia vivipara) were chosen as experimental models. Tetraselmis sp. showed the highest BPA tolerance, without a concentration-dependent response. Species sensitivity have increased from A. salina (LC_50,96h = 107.2 mg L^-1), followed by H. australis (LC_50,96h = 11.53.5 mg L^-1), to P. vivipara (LC_50,96h = 3.5 mg L^-1). Despite the toxicity hierarchy towards trophic levels, which partially supported our hypothesis, SSD did not evidence a clear pattern among estuarine-marine trophic groups. Our study disclosed the sensitivity of not yet investigated species to BPA and, in an integrative way, highlighted BPA toxic effects at different trophic levels. Although estimated acute hazardous concentration (HC5 = 1.18 mg L^-1) for estuarine and marine species was higher than environmentally relevant concentrations, sublethal adverse effects induced by BPA exposure may lead to unbalances in population levels and consequently affect the ecological functioning of tropical coastal systems.

Benzo[a]pyrene constrains embryo development via oxidative stress induction and modulates the transcriptional responses of molecular biomarkers in the marine medaka Oryzias javanicus

Embryos from the marine medaka fish Oryzias javanicus were treated with eight concentrations of benzo[a]pyrene (BaP) (0.001, 0.01, 0.1, 1, 2, 5, 10, or 20 μg L^--1) after they had been fertilized. Significant mortality and hatching delays were detected in embryos that had been exposed to 10 and 20 μg L^-1 BaP for 4 weeks. The mortality rate after hatching was higher in the medaka that had been previously exposed to > 2 μg L^-1 BaP. Significant elevations in intracellular reactive oxygen species and malondialdehyde contents were measured and the mRNA expressions of the antioxidant defense system genes (gst, sod, cat, and gpx) increased in the embryos exposed to 10 and 20 μg L^-1 BaP for 1 week. The hsp70, ahr, and cyp1a transcriptional responses were also significantly upregulated in the exposed groups after 1 week. The alterations to the in vivo parameters and molecular components suggested that waterborne BaP had a toxic effect on marine medaka embryos. Finally, fin defects, spinal curvature, and cardiac edema were highly induced when the embryos were exposed to > 5 μg L^-1 BaP.

Oxidative stress, ion concentration change and immune response in gills of common carp (Cyprinus carpio) under long-term exposure to bisphenol A

Bisphenol A (BPA) is a well-known phenolic environmental estrogen, widely distributed in the aquatic environment, which poses a toxic risk to the health of aquatic organisms. This study aimed to assess the effect of BPA on common carp gills by analyzing oxidative stress, ion equilibrium and immune response. Fish were exposed to five concentrations of BPA (0, 0.01, 0.1, 0.5, and 2 mg/L) for 30 days. Then gills were collected to assay biochemical parameters and gene expression. The results showed that BPA could decrease the levels of total antioxidant capacity (T-AOC), catalase (CAT), glutathione (GSH) and glutathione S-transferase (GST) and increase the levels of superoxide dismutase (SOD), malondialdehyde (MDA) and 8-hydroxy-2 deoxyguanosine (8-OHdG). The gene expression showed that BPA (2 mg/L) could affect the nuclear erythroid 2-related factor 2 (nrf2) signaling pathway, upregulate the gene expression of nrf2 and heme oxygenase 1 (ho-1). Meanwhile, BPA was found to change the activity of Na⁺/K⁺ ATPase, and increased the concentrations of Na⁺ and Ca²⁺ in gills of common carp. Also, high BPA concentration (0.5 or 2 mg/L) exposure increased the activity of alkaline phosphatase (AKP), blocked mRNA level of lysozyme-c (c-lyz), activated Toll-like receptors (TLRs) signaling pathway, enhanced the mRNA levels of toll-like receptor 2 (tlr2), receptor 4 (tlr4), myeloid differentiation factor 88 (myd88), interferon regulatory factor 3 (irf3), interleukin 1β (il-1β), interleukin 6 (il-6) and interleukin 10 (il-10). Overall, these results suggested that high BPA could induce oxidative damage, ion imbalance, immunosuppression and inflammatory response in gills of common carp.

Skeletal Muscle Lipidomics as a New Tool to Determine Altered Lipid Homeostasis in Fish Exposed to Urban and Industrial Wastewaters

This work applies ultrahigh performance liquid chromatography coupled with high-resolution mass spectrometry (UPLC-HRMS) to characterize for the first time the lipidome of the skeletal muscle of two fish species (Barbus meridionalis, Squalius laietanus) collected in a Mediterranean River affected by urban and industrial wastewater outflows. The untargeted analysis allowed a clear separation of the lipidome of fish from polluted and reference sites; phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), and their lyso and ether-linked forms were among the distinctive features. The targeted analysis consistently detected a decrease in PC-plasmalogens (36:4, 36:6, 38:6) and highly unsaturated PCs (36:5, 36:6, 38:6, 40:6, 40:7) and an increase in plasmanyl-PCs (36:5, 38:5), lyso-PCs (16:1, 18:1, 22:4) and cholesteryl esters (CEs) (16:0, 18:0, 20:4) in fish from polluted sites. These lipid profiles were indicative of oxidative stress and dysregulation of cholesterol homeostasis in fish from polluted sites. This methodology represents a promising tool for the development of novel noninvasive diagnostic methods based on muscle tissue biopsies to assess the effects of water pollution in wildlife.

Lipid Metabolism Alteration by Endocrine Disruptors in Animal Models: An Overview

Exposure to potential Endocrine Disrupting Chemicals (EDCs) pose a documented risk to both wildlife and human health. Many studies so far described declining sperm counts, genital malformations, early puberty onset, highlighting the negative impact on reproduction caused by the exposure to many anthropogenic chemicals. In the last years, increasing evidence suggested that these compounds, other than altering reproduction, affect metabolism and induce the onset of obesity and metabolic disorders. According to the "environmental obesogens" hypothesis, evidence exists that exposure to potential EDCs during critical periods when adipocytes are differentiating, and organs are developing, can induce diseases that manifest later in the life. This review summarizes the effects occurring at the hepatic level in different animal models, describing morphological alterations and changes of molecular pathways elicited by the toxicant exposure. Results currently available demonstrated that these chemicals impair normal metabolic processes via interaction with members of the nuclear receptor superfamily, including steroid hormone receptors, thyroid hormone receptors, retinoid X receptors, peroxisome proliferator-activated receptors, liver X receptors, and farnesoid X receptors. In addition, novel results revealed that EDC exposure can either affect circadian rhythms as well as up-regulate the expression of signals belonging to the endocannabinoid system, in both cases leading to a remarkable increase of lipid accumulation. These results warrant further research and increase the interest toward the identification of new mechanisms for EDC metabolic alterations. The last part of this review article condenses recent evidences on the ability of potential EDCs to cause "transgenerational effects" by a single prenatal or early life exposure. On this regard, there is compelling evidence that epigenetic modifications link developmental environmental insults to adult disease susceptibility. This review will contribute to summarize the mechanisms underlying the insurgence of EDC-induced metabolic alterations as well as to build integrated strategies for their better management. In fact, despite the large number of results obtained so far, there is still a great demand for the development of frameworks that can integrate mechanistic and toxicological/epidemiological observations. This would increase legal and governmental institution awareness on this critical environmental issue responsible for negative consequences in both wild species and human health.