Effects of developmental exposure to individual and combined PFAS on development and behavioral stress responses in larval zebrafish

Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic chemicals known for their widespread use and persistence in the environment. Laboratory and epidemiological studies investigating these compounds have signaled their neurotoxic and endocrine-disrupting propensities, prompting further research into their effects on behavioral stress responses and their potential role as risk factors for stress-related disorders such as anxiety and depression. This study elucidates the ramifications of early developmental exposures to individual and combined PFAS on the development and behavioral stress responses of larval zebrafish (Danio rerio), an established model in toxicological research. Wild-type zebrafish embryos were enzymatically dechorionated and exposed to PFOS, PFOA, PFHxS, and PFHxA between 6 and 120 h post-fertilization (hpf). We targeted environmentally relevant concentrations stemming from the USEPA 2016 Hazard Advisory Limit (HAL, 0.07 μg/L) and folds higher (0.35, 0.7, 1.75, and 3.5 μg/L). Evaluations at 120 hpf encompassed mortality, overall development, developmental defects, and larval activity both at baseline stress levels and following exposure to acute stressors (acoustic and visual). Larval exposure to PFOA, PFOS, or PFHxS (0.07 μg/L or higher) elicited significant increases in mortality rates, which capped at 23.1%. Exposure to individual chemicals resulted in limited effects on overall development but increased the prevalence of developmental defects in the body axis, swim bladder, pigmentation, and eyes, as well as the prevalence of yolk sac and pericardial edemas. Larval activity at baseline stress levels and following exposure to acute stimuli was significantly altered. Combined exposure to all four chemicals intensified the breadth of developmental and behavioral alterations, suggesting possible additive or synergistic effects. Our findings shed light on the developmental and neurobehavioral disturbances associated with developmental exposure to PFAS at environmentally relevant concentrations, the added risks of combined exposures to these chemicals, and their possible role as environmental risk factors for stress-related disorders.

Initial assessment of the toxicologic effects of leachates from 3-dimensional (3-D) printed objects on sperm quality in two model fish species

The use of 3-dimensional (3-D) printing is gaining popularity in life sciences and driving innovation in fields including aquatic sperm cryopreservation. Yet, little is known about the effects leachates from these objects may have on biological systems. In this study, we investigated if exposure to leachates from 3-D printed objects fabricated from different photo-curable resins could affect sperm quality in two model fish species, zebrafish (Danio rerio) and goldfish (Carassius auratus). Leachates were collected following contact periods of 10 min and 22 h with objects manufactured using a mask LCD resin printer and three different commercially available resins (i.e., standard, eco-friendly, and impact-resistant). Sperm cells were exposed to the leachates for 18 min, and parameters related to sperm motility, cell count, and membrane integrity were evaluated. All experiments were blinded. Leachate originating from contact with impact-resistant resin for 10 min significantly reduced the cell count of zebrafish sperm, while leachate originating from contact with standard resin for 22 h significantly increased the beat cross frequency of goldfish sperm. The changes were not observed across species and no adverse effects were recorded in percent motility, velocity, amplitude of lateral head movement, or membrane integrity of sperm. Our findings demonstrate that exposure to leachates from certain 3-D printed resins can affect sperm quality, while other resins may support sperm quality evaluation. Further investigations are warranted to assess other parameters, effects, and their biological relevance for a variety of aquatic species.

Fluorescent Reporter Zebrafish Line for Estrogenic Compound Screening Generated Using a CRISPR/Cas9-Mediated Knock-in System

An increasing number of compounds in our diet and environment are being identified as estrogenic, causing serious and detrimental effects on human, animal, and ecosystem health. Time- and cost-effective biological tools to detect and screen these compounds with potential high-throughput capabilities are in ever-growing demand. We generated a knock-in zebrafish transgenic line with enhanced green fluorescent protein (EGFP) driven by the regulatory region upstream of vitellogenin 1 (vtg1), a well-studied biomarker for estrogenic exposure, using CRISPR/Cas9 technology. Exposure to 17β-estradiol (E2: 0-625 nM) starting at 4-h post-fertilization in dechorionated embryos resulted in the significant induction of hepatic EGFP with ≥5 nM E2 as early as 3-days post-fertilization. Concentration- and time-dependent increase in the percentage of hepatic EGFP-positive larvae and extent of fluorescence expression, categorized into 3 expression levels, were observed with E2 exposure. A strong correlation between the levels of EGFP mRNA, vtg1 mRNA, and EGFP fluorescence levels were detected. Image analysis of the area and intensity of hepatic EGFP fluorescence resulted in high-fidelity quantitative measures that could be used in automated screening applications. In addition, exposure to bisphenol A (0-30 μM) resulted in quantitative responses showing promise for the use of this transgenic line to assess estrogenic activity of endocrine-disrupting chemicals. These results demonstrate that this novel knock-in zebrafish reporter allows for distinct screening of in vivo estrogenic effects, endpoints of which can be used for laboratory testing of samples for estimation of possible human and environmental risks.

Sex-specific endocrine-disrupting effects of three halogenated chemicals in Japanese medaka

Several halogenated chemicals are found in an array of products that can cause endocrine disruption. Human studies have shown that endocrine responses are sex specific, with females more likely to develop hypothyroidism and males more likely to have reproductive impairment. The objective of this study was to assess sex differences on thyroid and estrogenic effects after exposure of Japanese medaka (Oryzias latipes, SK2MC) to halogenated compounds. This strain is an excellent model for these studies as sex can be determined non-destructively a few hours postfertilization. Medaka embryos were exposed to sublethal concentrations of Tris(1,3-dichloro-2-propyl) phosphate (TDCPP, 0.019 mg/L), perfluorooctanoic acid (PFOA, 4.7 mg/L) and its next generation alternative, perfluorobutyric acid (PFBA, 137 mg/L). Methimazole (inhibits thyroid hormone synthesis) and the thyroid hormone triiodothyronine served as reference controls. Fish were exposed throughout embryo development until 10 days postfertilization. Females displayed significantly larger swim bladders (which are under thyroid hormone control) after exposure to all chemicals with the exception of triiodothyronine, which caused the opposite effect. Females exposed to TDCPP and PFOA had increased expression of vitellogenin and exposure to PFOA upregulated expression of multiple thyroid-related genes. Upregulation of estrogenic-regulated genes after exposure to TDCPP, PFOA and methimazole was only observed in males. Overall, our results suggest that females and males show an estrogenic response when exposed to these halogenated chemicals and that females appear more susceptible to thyroid-induced swim bladder dysfunction compared with males. These results further confirm the importance of considering sex effects when assessing the toxicity of endocrine-disrupting compounds.

Molecular signaling pathways elicited by 17α-ethinylestradiol in Japanese medaka male larvae undergoing gonadal differentiation

Estrogenic contaminants released into water bodies are potentially affecting the reproduction of aquatic organisms. Exposure to 17α-ethinylestradiol (EE2), a synthetic estrogen agonist commonly found in sewage effluents, has been shown to cause gonadal changes in male gonochoristic fish ranging from gonadal intersex to complete sex reversal. Although these gonadal changes have been well studied in Japanese medaka Oryzias latipes, the molecular mechanisms behind them are poorly understood. Our objective was to study the signaling pathways elicited by exposure to different concentrations of EE2 in this species. Embryos and larvae were sexed by the presence of leucophores and dmy expression (only in males). Male medaka were exposed to two EE2 concentrations (30 and 300 ng/L) during their gonadal differentiation period (7-22 dpf). The transcriptome of larvae was analyzed using RNA sequencing followed by pathway analysis. Genes involved in sex differentiation and gonadal development (e.g., cldn19, ctbp1, hsd17b4) showed a female-like expression pattern in EE2-exposed males with some genes changing in expression in an EE2 concentration-dependent manner. However, not all genes known to be involved in sex differentiation and gonadal development (e.g., wnt4b) were altered by EE2. Several of the prominently affected signaling pathways involved genes associated with steroidogenesis, steroid receptor signaling and steroid metabolism, such as cyp2b3, cyp3b40, cyp1a, hsd17b4. We also report on novel genes and pathways affected that might play a role in gonadal changes, including several genes associated with FXR/RXR and LXR/RXR activation networks. This study is the first to examine the transcriptomic changes in male fish resulting from exposure to EE2 during the gonadal differentiation period, providing new insights on the signaling pathways involved in the development of gonadal changes in gonochoristic fish.

Correction: Utilizing FBR to produce olefins from CO reduction using Fe–Mn nanoparticles on reduced graphene oxide catalysts and comparing the performance with SBR

Correction for ‘Utilizing FBR to produce olefins from CO reduction using Fe–Mn nanoparticles on reduced graphene oxide catalysts and comparing the performance with SBR’ by AL-Hassan Nasser et al., RSC Adv., 2018, 8, 42415–42423.

Gender differences in Egyptian patients hospitalized with heart failure: insights from the European Society of Cardiology Heart Failure Long-Term Registry

Aims

This analysis evaluates gender differences in the Egyptian cohort of patients hospitalized for acute heart failure (AHF) in the European Society of Cardiology Heart Failure Long‐Term Registry.

Methods and results

From April 2011 to September 2014, 1634 patients hospitalized with AHF were enrolled by 20 hospitals all over Egypt. Of these patients, 1112 (68%) patients were male and 522 (32%) were female. Women presented with a higher admission systolic blood pressure and resting heart rate. Compared with men, women had a higher body mass index (32.5 ± 9.0 vs. 29.3 ± 4.9, P < 0.001), more frequent atrial fibrillation (34.7% vs. 22.4%, P < 0.001), and anaemia defined by haemoglobin < 12 g/dL (83.1% vs. 58.4%, P < 0.001). Women were more likely to present with heart failure with preserved ejection fraction (29.7% vs. 10.6%, P < 0.001). Women had more frequent diabetes mellitus (48.1% vs. 41.6%, P < 0.05) and hypertension (48.7% vs. 39.3%, P < 0.001) than had men, whereas smoking was rare among them (8.8% vs. 82.9%, P < 0.005). There was no significant difference in the primary aetiology of heart failure between both sexes. ACE inhibitors, beta‐blockers, mineralocorticoid receptor antagonists, antiplatelets, statins, and nitrates were less frequently prescribed to women, whereas they more often received digoxin, amiodarone, anticoagulants, and calcium channel blockers. There was no significant difference in in‐hospital (5.7% vs. 4.6%, P = 0.39) and 1 year mortality (27.9% vs. 25.9%, P = 0.48) between women and men, respectively.

Conclusions

Men and women with AHF differ significantly in baseline clinical characteristics and management but not in adverse outcomes. These findings emphasize the importance of individualized management and need for more comprehensive recruitment of women in clinical trials.

Utilizing FBR to produce olefins from CO reduction using Fe–Mn nanoparticles on reduced graphene oxide catalysts and comparing the performance with SBR

Mn was used as a promoter for Fe nanoparticles (NPs) loaded on reduced graphene oxide (rGO). The prepared catalysts were the unpromoted Fe/rGO catalysts along with two Mn promoted catalysts FeMn16 and FeMn29. These catalysts were used as Fischer–Tropsch catalysts in a Fixed Bed Reactor (FBR). The operating conditions of the reactor, namely temperature, pressure and space velocity, were varied to evaluate the catalyst performance and the olefin productivity. The olefins were produced in maximum yields of 34.5% and 31.3% with FeMn29 at 320 and 340 °C respectively. The ratio of light to heavy olefins was three times higher at 340 °C. The catalysts showed good stability up to 50 h of interrupted operation while varying the conditions at each interruption. The performance of the catalysts in the FBR was compared with a previous investigation carried out in an SBR under identical conditions with the same catalysts. The FBR was found to be more Mn tolerant than the SBR, giving very high conversion activity with high Mn concentrations (FeMn29). The FBR produced olefins in much higher yields than the SBR. The SBR was more selective to light olefins at low temperatures and high Mn loading levels, while the FBR produced light olefins at higher selectivities at high temperatures and high Mn concentrations.

Producing olefin rich products from the FTS reaction in both FBR and SBR reactors using Fe–Mn/rGO catalysts.

Thyroid disrupting effects of halogenated and next generation chemicals on the swim bladder development of zebrafish

Endocrine disrupting chemicals (EDCs) can alter thyroid function and adversely affect growth and development. Halogenated compounds, such as perfluorinated chemicals commonly used in food packaging, and brominated flame retardants used in a broad range of products from clothing to electronics, can act as thyroid disruptors. Due to the adverse effects of these compounds, there is a need for the development of safer next generation chemicals. The objective of this study was to test the thyroid disruption potential of old use and next generation halogenated chemicals. Zebrafish embryos were exposed to three old use compounds, perfluorooctanoic acid (PFOA), tetrabromobisphenol A (TBBPA) and tris (1,3-dichloro-2-propyl) phosphate (TDCPP) and two next generation chemicals, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxdie (DOPO) and perfluorobutyric acid (PFBA). Sub-chronic (0-6days post fertilization (dpf)) and chronic (0-28dpf) exposures were conducted at 1% of the concentration known to kill 50% (LC₅₀) of the population. Changes in the surface area of the swim bladder as well as in expression levels of genes involved in the thyroid control of swim bladder inflation were measured. At 6dpf, zebrafish exposed to all halogenated chemicals, both old use and next generation, had smaller posterior swim bladder and increased expression in the gene encoding thyroid peroxidase, tpo and the genes encoding two swim bladder surfactant proteins, sp-a and sp-c. These results mirrored the effects of thyroid hormone-exposed positive controls. Fish exposed to a TPO inhibitor (methimazole, MMI) had a decrease in tpo expression levels at 28dpf. Effects on the anterior swim bladder at 28dpf, after exposure to MMI as well as both old and new halogenated chemicals, were the same, i.e., absence of SB in ∼50% of fish, which were also of smaller body size. Overall, our results suggest thyroid disruption by the halogenated compounds tested via the swim bladder surfactant system. However, with the exception of TBBPA and TDCPP, the concentrations tested (∼5-137ppm) are not likely to be found in the environment.