Dopaminergic and serotoninergic neurotoxicity of lanthanide phosphate (TbPO4) in developing zebrafish.

Rare earth elements (REEs) are exploited for global use in manufacturing. Such activities result in their release into the environment and the transformation into more stable phosphate deposition. The objective of this study was to evaluate molecular and behavioral changes of zebrafish exposed to the synthesized terbium phosphate (TbPO4) at concentrations of 10, 20, and 50 mg/L and to determine its potential for neurotoxicity. Metabolomics related to neurotransmitters, and assessment of transcripts and proteins were conducted to uncover the molecular mechanisms underlying TbPO4 with emphasis on neurotransmitter systems. Exposure to 20 mg/L TbPO4 induced larval hyperactivity and perturbed the cholinergic system in zebrafish. Based on metabolomics related to neurotransmitters, dopamine (DA), serotonin (5-HT), and many of their precursors and metabolites were decreased in abundance by TbPO4. In addition, the expression levels of transcripts related to the synthesis, transport, receptor binding, and metabolism of DA and 5-HT were analyzed at the mRNA and protein levels. Transcript and protein levels for tyrosine hydroxylase (TH), the rate-limiting enzyme for DA synthesis, were down-regulated in larval fish. Monoamine oxidase (MAO), an enzyme that catabolizes monoamines DA and 5-HT, was also reduced in mRNA abundance. We hypothesize that DA synthesis and monoamine metabolism are associated with behavioral alterations. This study elucidates putative mechanisms and exposure risks to wildlife and humans by characterizing phosphatic REE-induced neurotoxicity in developing zebrafish.

Ultrasensitive and Rapid Visual Detection of Escherichia coli O157:H7 Based on RAA-CRISPR/Cas12a System.

Escherichia coli (E. coli) O157:H7 is a major foodborne and waterborne pathogen that can threaten human health. Due to its high toxicity at low concentrations, it is crucial to establish a time-saving and highly sensitive in situ detection method. Herein, we developed a rapid, ultrasensitive, and visualized method for detecting E. coli O157:H7 based on a combination of Recombinase-Aided Amplification (RAA) and CRISPR/Cas12a technology. The CRISPR/Cas12a-based system was pre-amplified using the RAA method, which showed high sensitivity and enabled detecting as low as ~1 CFU/mL (fluorescence method) and 1 × 102 CFU/mL (lateral flow assay) of E. coli O157:H7, which was much lower than the detection limit of the traditional real-time PCR technology (103 CFU/mL) and ELISA (104~107 CFU/mL). In addition, we demonstrated that this method still has good applicability in practical samples by simulating the detection in real milk and drinking water samples. Importantly, our RAA-CRISPR/Cas12a detection system could complete the overall process (including extraction, amplification, and detection) within 55 min under optimized conditions, which is faster than most other reported sensors, which take several hours to several days. The signal readout could also be visualized by fluorescence generated with a handheld UV lamp or a naked-eye-detected lateral flow assay depending on the DNA reporters used. Because of the advantages of being fast, having high sensitivity, and not requiring sophisticated equipment, this method has a promising application prospect for in situ detection of trace amounts of pathogens.

Novel Microbial Palladium Nanoparticles with a High Photothermal Effect for Antibacterial Applications.

Novel biocompatible palladium nanoparticles (Pd-NPs) have been prepared by microorganisms via Bacillus megaterium Y-4. It was demonstrated that ultrasonication treatment of biologically reduced Pd-NPs impart a much higher absorption in NIR regions and a better photothermal conversion efficiency to the material. The as-prepared material showed excellent biocompatibility and antibacterial activity under NIR irradiation. In less than 10 min, the disinfection efficiency for a low dosage of Pd-NPs (20 mg/L) was 99.99% toward both Staphylococcus aureus and Escherichia coli. The exclusive and even dispersed microbial Pd-NPs display a high efficiency of photothermal conversion under the irradiation of NIR, which endows them with excellent antibacterial activity in a low dosage.

Nonmonotonic effect of CuO nanoparticles on medium-chain carboxylates production from waste activated sludge.

The growing applications of CuO nanoparticles (NPs) in industrial and agriculture has increased their concentrations in wastewater and subsequently accumulated in waste activated sludge (WAS), raising concerns about their impact on reutilization of WAS, especially on the medium-chain carboxylates (MCCs) production from anaerobic fermentation of WAS. Here we showed that CuO NPs at 10-50 mg/g-TS can significantly inhibit MCCs production, and reactive oxygen species generation was revealed to be the key factor linked to the phenomena. At lower CuO NPs concentrations (0.5-2.5 mg/g-TS), however, MCCs production was enhanced, with a maximum level of 37% compared to the control. The combination of molecular approaches and metaproteomic analysis revealed that although low dosage CuO NPs (2.5 mg/g-TS) weakly inhibited chain elongation process, they displayed contributive characteristics both in WAS solubilization and transport/metabolism of carbohydrate. These results demonstrated that the complex microbial processes for MCCs production in the anaerobic fermentation of WAS can be affected by CuO NPs in a dosage-dependent manner via regulating microbial protein expression level. Our findings can provide new insights into the influence of CuO NPs on anaerobic fermentation process and shed light on the treatment option for the resource utilization of CuO NPs polluted WAS.

Construction of K and Tb Co-doped MnO2 nanoparticles for enhanced oxidation and detoxication of organic dye waste.

Developing low-cost and efficient materials for dye pollutant removal under mild condition remains a great challenge. Here K+ and Tb3+ co-doped porous MnO2 (K-Tb-MnO2) nanoparticles with tailored properties including crystal structure, surface area and catalytic activity have been synthesized. Experimental results reveal that K-Tb-MnO2 nanoparticle has higher specific surface area, Mn3+ content and surface oxygen vacancies than pristine MnO2 nanoparticle and single-doped MnO2 materials, showing the uniqueness of dual-doped metal ions. Using methyl blue (MB) as a model pollutant, its removal efficiency by K-Tb-MnO2 nanoparticles within 5 min is 93.6%, which is 18, 8.3, and 2.9 times higher than that of MnO2, K-MnO2, and Tb-MnO2 nanomaterials, respectively. Oxalic acid triggered MnO2 material dissolving assay and FT-IR spectrum suggested that remarkable performance of K-Tb-MnO2 nanoparticle toward MB removal can be attributed to a combined effect of adsorption (16% MB removal) and catalytic degradation (84% MB removal). Moreover, K-Tb-MnO2 nanoparticle mediated MB degradation is demonstrated to be a combination of non-radical oxidation by Mn3+ and radical-participated degradation, with 1O2 as the main species. And the intermediates and pathways of MB degradation were studied by liquid chromatography-mass spectrometry. Importantly, cell viability experiment suggests that the toxicity of MB dye could be efficiently alleviated after the treatment with K-Tb-MnO2 nanoparticle. These results demonstrate the great potential of the novel K-Tb-MnO2 particles to be used as a highly effective nanomaterials to reduce the risk of dye wastes toward the environment and human health.

A TbPO4-based capturer for environmental extracellular antibiotic genes by interrogating lanthanide phosphates nanoneedles.

Accurate determination of antibiotic resistance genes (ARGs) in environmental DNA molecules (eDNA) is challenging owing to its low abundance in the aquatic environment. Here we report a facile and cost-efficient approach to extract trace amount of eDNAs in the aquatic environment using LnPO4 nanomaterials. Among the nanomaterials, less crystalline TbPO4 nanoneedles was identified as the most prominent candidate for long stranded DNA and short stranded DNA with adsorption efficiency above 97%. The adsorbed DNA was washed off from TbPO4 nanoneedles by optimized eluant (85% PBS, 15% EtOH, 4 g/L glycine, pH 10.0) with an optimal DNA recovery of 78.83%. Our approach showed a comparable or better eDNA extraction efficiency than a commercial extraction method for different environmental samples, but 89% less cost. The high purity of the extracted eDNA was demonstrated by a high A260/280 ratio. Using qPCR experiment, the occurrence of six common ARGs in the eDNA were detected with abundance ranging from 4.06 × 103 to 3.51 × 109 copies/L in river samples. This specific DNA capturer is valuable for the evaluation of spatial and temporal dynamic of ARGs pollution to provide insight into the potential risk with regard to the human health.

Di(2-ethylhexyl) phthalate induces apoptosis through mitochondrial pathway in GC-2spd cells.

Di(2-ethylhexyl) phthalate (DEHP), a plasticizer of synthetic polymers, is a well-known endocrine disrupting chemical (EDC) and reproductive toxicant. Addressing the unclear mechanism of DEHP-induced reproductive dysfunction, this study used GC-2spd cells to investigate the molecular mechanism involved in the DEHP-induced toxicity in the male reproductive system. The results indicated that the apoptotic cell death was significantly induced by DEHP exposure over 100 µM. Furthermore, DEHP treatment could induce oxidative stress in GC-2spd cells involving in the decrease of superoxide dismutase (SOD) activity (200 µM) and glutathione peroxidase (GSH-Px) activity (50 and 100 µM). In addition, DEHP induction also caused the elevated ratios of Bax/Bcl-2, release of cytochrome c and decomposition of procaspase-3 and procaspase-9 in GC-2spd cells. Taken together, our work provided the evidence that DEHP exposure might induce apoptosis of GC-2spd cells via mitochondria pathway mediated by oxidative stress. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1055-1064, 2017.

Di-(2-ethylhexyl) phthalate induces apoptosis of GC-2spd cells via TR4/Bcl-2 pathway.

Di-(2-ethylhexyl) phthalate (DEHP) is a widely used environmental endocrine disruptor. Many studies have reported that DEHP exposure causes reproductive toxicity and cells apoptosis. However, the mechanism by which DEHP exposure causes male reproductive toxicity remains unknown. This study investigated the role of the testicular orphan nuclear receptor4 (TR4)/Bcl-2 pathway in apoptosis induced by DEHP, which resulted in reproductive damage. To elucidate the mechanism underpinning the male reproductive toxicity of DEHP, we sought to investigate apoptotic effects, expression levels of TR4/Bcl-2 pathway in GC-2spd cells, including TR4, Bcl-2 and caspase-3. GC-2spd cells were exposed to various concentrations of DEHP (0, 50, 100, or 200µM). The results indicated that, with the increase of the concentrations of DEHP, the survival rate of cell decreased gradually. DEHP exposure at over 100µM significantly induced apoptotic cell death. DEHP decreased SOD and GSH-Px activity in 200µM group. Compared to the control group, the mRNA levels of caspase-3 increased significantly, however, Bcl-2 mRNA decreased (P<0.05). In addition, there was a significant reduction in TR4, Bcl-2 and procaspase-3 protein levels. Taken together, these results lead us to speculate that in vitro exposure to DEHP might induce apoptosis in GC-2spd cells through the TR4/Bcl-2 pathway.