The combined toxicity of ultra-small SiO2 nanoparticles and bisphenol A (BPA) in the development of zebrafish

Toxic endpoints or ubiquitous expression?

This opinion article questions the underlying causes of malformations observed in early developmental stages of zebrafish exposed to a range of chemicals. The research focuses on determining whether these developmental abnormalities arise due to the inherent sensitivity of zebrafish to chemical exposure or if they are related to the ubiquitous expression of certain genes within the zebrafish genome. By analysing different studies on zebrafish embryos to various chemical agents and analysing the resulting malformations, the study aims to differentiate between the effects of chemical sensitivity and the role of gene expression in developmental disruptions. Findings from this investigation will contribute to a deeper understanding of the mechanisms driving developmental toxicity in zebrafish, with implications for broader environmental and genetic research.

Metabolic disrupting chemicals in the intestine: the need for biologically relevant models: Zebrafish: what can we learn from this small environment-sensitive fish?

Although the concept of endocrine disruptors first appeared almost 30 years ago, the relatively recent involvement of these substances in the etiology of metabolic pathologies (obesity, diabetes, hepatic steatosis, etc.) has given rise to the concept of Metabolic Disrupting Chemicals (MDCs). Organs such as the liver and adipose tissue have been well studied in the context of metabolic disruption by these substances. The intestine, however, has been relatively unexplored despite its close link with these organs. In vivo models are useful for the study of the effects of MDCs in the intestine and, in addition, allow investigations into interactions with the rest of the organism. In the latter respect, the zebrafish is an animal model which is used increasingly for the characterization of endocrine disruptors and its use as a model for assessing effects on the intestine will, no doubt, expand. This review aims to highlight the importance of the intestine in metabolism and present the zebrafish as a relevant alternative model for investigating the effect of pollutants in the intestine by focusing, in particular, on cytochrome P450 3A (CYP3A), one of the major molecular players in endogenous and MDCs metabolism in the gut.

Comparative toxicological assessment of 2 bisphenols using a systems approach: evaluation of the behavioral and transcriptomic responses of Danio rerio to bisphenol A and tetrabromobisphenol A

The zebrafish (Danio rerio) is becoming a critical component of new approach methods (NAMs) in chemical risk assessment. As a whole organism in vitro NAM, the zebrafish model offers significant advantages over individual cell-line testing, including toxicokinetic and toxicodynamic competencies. A transcriptomic approach not only allows for insight into mechanism of action for both apical endpoints and unobservable adverse outcomes, but also changes in gene expression induced by lower, environmentally relevant concentrations. In this study, we used a larval zebrafish model to assess the behavioral and transcriptomic alterations caused by subphenotypic concentrations of 2 chemicals with the same structural backbone, the endocrine-disrupting chemicals bisphenol A and tetrabromobisphenol A. Following assessment of behavioral toxicity, we used a transcriptomic approach to identify molecular pathways associated with previously described phenotypes. We also determined the transcriptomic point of departure for each chemical by modeling gene expression changes as continuous systems which allows for the identification of a single concentration at which toxic effects can be predicted. This can then be investigated with confirmatory cell-based testing in an integrated approach to testing and assessment to determine risk to human health and the environment with greater confidence. This paper demonstrates the impact of using a multi-faceted approach for evaluating the physiological and neurotoxic effects of exposure to structurally related chemicals. By comparing phenotypic effects with transcriptomic outcomes, we were able to differentiate, characterize, and rank the toxicities of related bisphenols, which demonstrates methodological advantages unique to the larval zebrafish NAM.

Sensitivity and reusability of a simple microbial fuel cell-based sensor for detecting bisphenol A in wastewater

Polycarbonate plastic processing wastewater contains high concentrations of bisphenol A (BPA), requiring a real-time technology to monitor wastewater containing BPA. Since the activity of electrogenic microorganisms on the anode surface of the microbial fuel cell (MFC) sensor is inhibited by exposure to contaminants, the toxicity of contaminants in wastewater can be determined by observing the variation in voltage output from the MFC sensor. The simple MFC sensor that is developed in this work exhibited a significant decrease in voltage output in BPA-containing wastewater concentration of 5-100 mg/L. Sensitivity analysis revealed that the voltage change (ΔV) was strongly correlated with the BPA concentration, with R² as high as 0.97. This study was the first to investigate the number of repeated uses of the MFC sensor, using sodium acetate as the regeneration solution for the MFC sensor, leading to a successful recovery of detection performance. However, as the number of uses increased (up to the third or fourth use), the ΔV of the MFC sensor for BPA gradually decreased and the sensitivity decreased significantly from 0.238 mV/mg/L to 0.027 mV/mg/L. In the low BPA concentration range (≦20 mg/L), the MFC sensor can be reused up to 5 times, demonstrating that the proposed MFC sensor can be reused. Microorganisms contribute to the power generation of the MFC sensor, which can be exploited in the detection of pollutants, enabling the determination of wastewater toxicity and providing early warnings of thereof. Conventional MFC sensors are complex and lack the ability to explore repeated use, so they are not easily applied to actual wastewater detection. The proposed MFC sensor has many advantages such as simplicity, rapid detection, and reusability, solving the problem of the high cost of using disposable MFC sensors and making them feasible for practical use.

Characterization and preliminary safety evaluation of nano-SiO2 isolated from instant coffee

The physiological and toxicological evaluation of nano-silicon dioxide (nano-SiO2) particles in food is important for ensuring food safety. In this study, nano-SiO2 particles isolated from five brands of instant coffee, were structurally characterized using transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, dynamic light scattering, and zeta potential analyses. Their toxicity was assessed by measuring cell viability, membrane integrity, and reactive oxygen species (ROS) levels in model gastrointestinal cells (GES-1 and Caco-2). Additionally, mortality, deformity rate, heart rate and death of whole zebra fish embryos were measured. The five types of nano-SiO2 samples comprised amorphous particles with a purity of approximately 99%, which met the food additive standard. Considering that the original particle size ranged from 10 to 50 nm, the samples were classified as nano-SiO2 food additives. Nano-SiO2 did not significantly impact the activity of GES-1 or Caco-2 cells, and no significant cell membrane damage was observed (Caco-2 cells exhibited mild micro damage); however, a slight increase in intracellular RPS levels was detected. Moreover, nano-SiO2 was found to cause head deformity, pericardial edema, yolk sac edema and tail bending. Collectively, the results show that nano-SiO2 time- and dose-dependently affects GES-1 and Caco-2 cell viability, as well as the mortality, heart rate, and abnormality rate of zebra fish embryos. Specifically, a high concentration (≥ 200 μg/mL) and long exposure time (≥ 48 h) of food additive nano-SiO2 affected GES-1, Caco-2 cells, and the gastrointestinal tract in zebra fish embryos.