Cytotoxic impacts of treated electroplating industrial effluent and the comparative effect of their metal components (Zn, Hg, and Zn+Hg) on Danio rerio gill (DrG) cell line

Heterogeneous Single-Cell Distribution of Trace-Level Metal Mixtures in Tetrahymena thermophila Using Mass Cytometry

The uptake of heavy metals by unicellular organisms can lead to the bioaccumulation of these metals in higher organisms, detrimentally affecting organismal health and ultimately impacts the ecosystems. By studying the uptake and accumulation of heavy metals in unicellular organisms, we gain insights into potential risks associated with low-dose heavy metal exposure in aquatic environments. Thus, to investigate the accumulation characteristics of Mo, Ag, Cd, Sn, Sb, Hg, Tl, and Pb mixtures in single Tetrahymena thermophila cells, we developed a label-free approach for the simultaneous absolute quantification of multiple metals in a single cell using mass cytometry. Our results demonstrated the dynamic changes in metal concentrations in T. thermophila, and the competition between metals in uptake and excretory pathways resulted in heterogeneous accumulation and bioconcentration of these metals. Additionally, our findings revealed the limited capacity of T. thermophila to excrete Cd and Hg, suggesting a higher risk for T. thermophila cells when exposed to Cd and Hg over an extended period. Therefore, the current study provides valuable data for a more comprehensive understanding of the impact of low-dose heavy metals on aquatic ecosystems.

BIF-induced ROS-mediated cytotoxicity and genotoxicity in embryonic cell culture of Daphnia magna

Bifenthrin (BIF) is a widely used synthetic pyrethroid insecticide that poses significant risks to the environment, particularly to aquatic ecosystems. In the present study, the cytotoxic and genotoxic effects of BIF on Daphnia magna cells were evaluated using in vitro methods. To achieve this, we developed a novel embryonic cell culture system from D.magna using Modified Schneider's Insect Medium (MSIM), which demonstrated remarkable viability for over two months. The lethal concentration 50 (LC50) values of BIF were determined using this cell culture system through XTT (2,3-bis-(2‑methoxy-4-nitro-5-sulphenyl)-(2H)-tetrazolium-5-carboxanilide)assays, yielding values of 7.4 µg/mL and 4.3 µg/mL for 24 h and 48 h exposures, respectively. A fluorometric intracellular reactive oxygen species (ROS) assay was employed to measure ROS production, revealing that BIF exposure induced oxidative stress in a dose-dependent manner. The activities of Glutathione peroxidase (GPx), glutathione (GSH), and glutathione-S-transferase (GST) were significantly reduced, indicating oxidative damage. Co-treatment with N-acetylcysteine(NAC) mitigated these effects, restoring antioxidant enzyme activity and reducing (ROS) levels. Gene expression analysis via quantitative real-time PCR (qPCR) showed upregulation of stress-related genes (hsp70, hsp90) and antioxidant genes (Mn/ZnSod, cat) following exposure to LC50 concentrations of BIF. However, prolonged exposure led to a downregulation of these genes, suggesting cumulative effects over time. The comet assay confirmed that BIF caused genotoxicity, as evidenced by significant increases in comet and tail lengths. Co-treatment with NAC effectively mitigated these genotoxic effects. This study highlighted the cytotoxic and genotoxic potential of BIF in aquatic organisms and suggested the need for environmentally friendly pest control strategies. Also, the findings confirmed the reliability of D. magna embryonic cell cultures for assessing the toxicological effects of environmental pollutants, offering new possibilities for in vitro toxicity testing at cellular and molecular levels.

Establishment of a cell culture from Daphnia magna as an in vitro model for (eco)toxicology assays: Case study using Bisphenol A as a representative cytotoxic and endocrine disrupting chemical

Bisphenol A (BPA) is a widely used industrial compound found in polycarbonate plastics, epoxy resin, and various polymer materials, leading to its ubiquitous presence in the environment. The toxicity of BPA to aquatic organisms has been well documented following in vivo exposure scenarios, with known cytotoxic and endocrine-disrupting effects. As such, BPA was used in this study as a well-characterized chemical to implement more ethical and resource-efficient scientific practices in toxicity testing through new approach methods (NAMs). Due to the frequent use of Daphnia spp. as a model organism in toxicology, we developed an in vitro cell culture system from Daphnia magna embryos, with optimized medium to support cell longevity. The cultures were maintained for up to two months, demonstrating their stability and suitability for cytotoxicity studies. Using this novel system, lethal concentration 50 (LC50) values were determined at the 24 and 48 h time points following BPA exposure. Subsequently, oxidative stress, endocrine disruption, and DNA damage were assessed through gene expression, activity assays, and a comet assay in BPA-exposed cells. LC50 values of 52 µM and 20 µM BPA were calculated after 24 and 48 h exposures, respectively. BPA cells exposed to 20 and 52 µM had significantly increased GSH, GPx, and GST activity levels. mRNA expression analysis revealed significant upregulations in the expression of hsp70, hsp90, gst, gpx, vtg1, and cyp4, with downregulations of sod, cat, and ecr following BPA exposure. Furthermore, comet assays showed a significantly higher level of DNA damage induced by BPA compared to controls, with greater comet and tail lengths. This study established a novel in vitro Daphnia model, using BPA as a case study for determining toxic effects, further highlighting the importance and applicability of utilizing alternative methods in ecotoxicological research through reducing animal use.

Toxicity assessment of DMSO extracts of environmental aged beached plastics using human cell lines

Plastic products contain complex mixtures of chemical compounds that are incorporated into polymers to improve material properties. Besides the intentional chemical additives, other compounds including residual monomers and non-intentionnaly added substances (NIAS) as well as sorbed pollutants are usually also present in aged plastic. Since most of these substances are only loosely bound to the polymer via non-covalently interactions, i.e., van der Waals forces, they may leach to the surrounding environment. Although there is increasing knowledge about toxicity of weathered plastic to aquatic organisms, only little is known about how plastic associated chemicals affect human health. Seafood consumption is one of the routes of human exposure to microplastics. The aim of this study was to evaluate the ability of naturally aged plastic associated chemicals to induce harmful effects to human health via the consumption of MP-contaminated seafood. Human colorectal adenocarcinoma Caco-2 and human hepatocyte carcinoma HepG2 cells were selected as model of the colon and liver cells respectively. They are known for their high capacity to metabolize organic contaminants. Both cell lines were exposed to DMSO extracts of different plastics to investigate the effects of chemicals on cell viability, oxidative stress induction and genotoxicity. In addition, the estrogenic effects of DMSO-extracts were evaluated using an estrogen-dependent reporter gene assay in T47D-Kbluc human breast cancer cells. Chemical profiles of the DMSO extracts were polymer-dependent, with polyvinyl chloride (PVC) highly contaminated with metals while polypropylene (PP) contained the lowest concentration of metals. Organic pollutants, including polycyclic aromatic hydrocarbons, were mainly found in PVC, high density polyethylene (HDPE) and PP extracts, whereas other extracted plastics had less (PP) to no organic contamination (polyethylene terephthalate PET). PVC was the most toxic plastic inducing cytotoxicity for both cell lines. DNA damage was observed for Caco-2 cells exposure to HDPE, PVC and nylon. Reactive oxygen species were induced only with nylon extracts in intestinal cells. No toxicity was observed for PP and PET and none of the tested plastics had any estrogenic effect. Our results demonstrate that some environmental aged plastic material released a variety of known and unknown chemical compounds some of which are toxic in vitro and contribute to the knowledge on adverse human health effects of plastics.

Effects of blood metal(loid) concentrations on genomic damages in sharks

The use of effect biomarkers has contributed to the understanding of the sublethal effects of contaminants on different organisms. However, the analysis of genotoxic markers as an indicator of organism and environmental health in sharks is underexplored. Thus, the present study investigated the relationship between the genomic damage frequency in erythrocytes and metal(loid) concentrations in whole blood of three shark species (Galeocerdo cuvier, Negaprion brevirostris and Ginglymostoma cirratum), taking into account climatic seasonality. The results showed that G. cuvier, an apex predator, presented the highest total erythrocyte genomic damage frequencies together with the highest mean whole blood concentrations of Al, Cd, Cr, Fe, Mn, Ni, Pb and Zn. The shark N. brevirostris also presented high levels of metal(loid), indicating a greater susceptibility to these contaminants in species that preferentially feed on fish. In contrast, G. cirratum, a mesopredator, presented the lowest erythrocyte damage frequencies and whole blood metal(loid) concentrations. The presence of micronuclei was the most responsive biomarker, and Al, As and Zn had an important effect on the genomic damage frequencies for all species evaluated. Zn concentration influenced the binucleated cells frequencies and Al concentration had an effect on the total damage and micronuclei frequencies in G. cuvier and N. brevirostris. Binucleated cells and blebbed nuclei frequencies were affected by As concentration, especially in G. cirratum, while showing a strong and positive correlation with most of the metals analyzed. Nonetheless, baseline levels of metal(loid) blood concentrations and erythrocyte genomic damage frequencies in sharks have not yet been established. Therefore, minimum risk levels of blood contaminants concentrations on the health of these animals have also not been determined. However, the high genomic instability observed in sharks is of concern considering the current health status of these animals, as well as the quality of the environment studied.

Complexation-based selectivity of organic phosphonates adsorption from high-salinity water by neodymium-doped nanocomposite

Organic phosphonates have been widely used in various industries and are ubiquitous in wastewaters, and efficient removal of phosphonates is still a challenge for the conventional processes because of the severe interferences from the complex water constitutions. Herein, an Nd-based nanocomposite (HNdO@PsAX) was fabricated by immobilizing hydrated neodymium oxide (HNdO) nanoparticles inside a polystyrene anion exchanger (PsAX) to remove phosphonates from high-salinity aqueous media. Batch experiments demonstrated that HNdO@PsAX had an excellent adsorption capacity (∼90.5 mg P/g-Nd) towards a typical phosphonate (1-hydrox-yethylidene-1,1-diphosphonic acid, HEDP) from the background of 8 g/L NaCl, whereas negligible HEDP adsorption was achieved by PsAX. Attractively, various coexisting substances (humic acid, phosphate, citrate, EDTA, metal ligands, and anions) exerted negligible effects on the HEDP adsorption by HNdO@PsAX under high salinity. FT-IR and XPS analyses revealed that the inner-sphere complexation between HEDP and the immobilized HNdO nanoparticles is responsible for HEDP adsorption. Fixed-bed experiments further verified that HNdO@PsAX was capable of successively treating more than 4500 bed volumes (BV) of a synthetic high-salinity wastewater (1.0 mg P/L of HEDP), whereas only ∼2 BV of effective treatment capacity was received by PsAX. The exhausted HNdO@PsAX was amenable to a complete regeneration by a binary NaOHNaCl solution without significant loss in capacity. The capability in removing other organic phosphonates and treating a real electroplating wastewater by HNdO@PsAX was further validated. Generally, HNdO@PsAX exhibited a great potential in efficiently removing phosphonates from high-salinity wastewater.

Assessment of the water quality and toxicity effects on zebrafish (Danio rerio) of a stream near a phosphorus chemical plant in Guizhou Province, southwestern China

To reveal the influence of the phosphorus chemical industry (PCI) on regional water environmental quality and safety, the water quality and ecotoxicological effects of a stream near a phosphorus chemical plant (PCP) in Guizhou Province, southwestern China, were investigated based on water samples collected from the stream. The results showed that the average concentrations of NH3-N, TN, P, F-, Hg, Mn, and Ni were 3.14 mg/L, 30.09 mg/L, 3.34 mg/L, 1.18 mg/L, 1.06 μg/L, 45.82 μg/L, and 11.30 μg/L, respectively. The overall water quality of the stream was in the heavily polluted category, and NH3-N, TN, P, F-, and Hg were the main pollution factors. The degree of pollution was in the order of rainy period > transitional period > dry period, and the most polluted sample site was 1100 m from the PCP. After 28 days of exposure to stream water, there was no significant change in the growth parameters of zebrafish. The gills of zebrafish showed a small amount of epithelial cell detachment and a small amount of inflammatory cell infiltration, and the liver tissue displayed a large amount of hepatocyte degeneration with loose and lightly stained cytoplasm. Compared with the control group, the %DNA in tail, tail length, tail moment, and olive tail moment were significantly increased (p < 0.05), indicating that the water sample caused DNA damage in the peripheral blood erythrocytes of zebrafish. The stream water in the PCI area was found to be polluted and exhibited significant toxicity to zebrafish, which could pose a threat to regional ecological security.

Establishment of a cell line derived from the gills of Gymnocypris przewalskii, an endemic Schizothoracine fish from Qinghai Lake of Tibet Plateau

Gymnocypris przewalskii (Naked carp), a native teleost, plays an important role in maintaining the ecological balance of Lake Qinghai (altitude, 3.2 km), the largest saline lake in China. In this study, a new gill cell line from G. przewalskii was developed using the explant technique and named as GPG. This cell line was maintained in Dulbecco's Modified Eagle Medium (DMEM) (high glucose), supplemented with 15% fetal bovine serum (FBS), and was successfully subcultured up to 32 passages. Meanwhile, this cell line was also authenticated by sequencing the mitochondrial cytochrome C oxidase subunit I (COI) and 16S rRNA genes and by chromosome analysis. With the Cytomegalovirus (CMV) promoter, the GPG cell line could express green fluorescent protein (GFP) at about 5% transfection efficiency. MTT test showed that Clostridium botulinum toxin (BTX) was toxic to the cell line. After cryopreservation with 10% dimethyl sulfoxide (DMSO), this cell line could be successfully revived at an efficiency over 70%. This study revealed that the GPG cell line could be used as materials for physio-chemical investigation of G. przewalskii and also provided a tool for gene function study and toxicological reaction in vitro.

Toxicological assessment of functional polymer with single-walled carbon nanotubes in zebrafish embryos and its gill cell line

Carbon nanotubes (CNTs) have been widely used in developing polymer hybrid coatings for anticorrosive application. In the present study, poly [(3,5-dimethyl-lH-pyrazole-1-yl) methyl methacrylate-co-glycidyl methacrylate] (PyM) was prepared by solution polymerization. Single-wall carbon nanotubes (SWCNT) were incorporated in the PyM by solution blending technique at different proportions. The PyM and its SWCNT (PyM-SWCNT) nanocomposites were characterized by FT-IR spectroscopy, X-Ray Diffraction, FE-SEM and HR-TEM. Different concentrations of PyM or PyM-SWCNT prepared in the present study were assessed separately for their toxicity by in vivo and in vitro assays using zebrafish embryos and gill cell line of zebrafish (DrG), respectively. The nanocomposites at the concentration of 400 μg ml^-1 of PyM in 1.0% of SWCNT was found to be non-toxic and recommended for anticorrosive application whereas the nanocomposites with above 1% of SWCNT was found to be toxic. The nanocomposites with 1.5% of SWCNT delayed the hatching rate of eggs, decreased survival rate and heart beat in zebrafish embryos, and induced the morphological changes in DrG cells. Gene expression studies revealed that PyM-SWCNT with high concentration of SWCNT induced oxidative stress by activating ROS generations in zebrafish embryos and DrG cells. The immersion study of uncoated and coated with recommended concentration of PyM-SWCNT on mild steel (MS) in sea water was studied using FE-SEM and EDS, and the results showed effective corrosion protection without leaching behaviour. The nanocomposites with novel polymer in the present study may be used in the industry for anticorrosive purpose.