Tetrabromobisphenol A induces neuronal cytotoxicity by inhibiting PINK1-Parkin-mediated mitophagy via upregulating ATF3 expression.

Tetrabromobisphenol A (TBBPA), as a widely used brominated flame retardant, has been implicated as a potential neurotoxicant. However, the mechanism of TBBPA-induced neurotoxicity has not been fully elucidated yet. In this study, using mouse hippocampal neuron cell HT22 as the in vitro model, the neuronal cytotoxicity of TBBPA and the mechanism by focusing on mitophagy have been studied. We found that neuronal cytotoxic effects were indeed induced by TBBPA exposure at concentrations of >20 µM for 24 h, including decreased cell viability (to 92.38 % at 20 µM; 18.25 % at 80 µM), enhanced ROS (enhanced 53.26 % at IC50 of 60 µM, compared with that in the control group) and mitochondrial ROS (mtROS) levels (enhanced 24.12 % at 60 µM), reduced mitochondrial membrane potential (MMP) (decreased 33.60 % at 60 µM). As a protective mechanism in cells, autophagy was initiated; however, mitophagy was inhibited, where PINK1 (PINK1-Parkin activation is critical in the depolarized MMP-induced mitophagy) expression was found to be repressed and decreased, further leading to the failure of Parkin recruitment to the damaged mitochondria. Mitophagy activator, nicotinamide mononucleotide (ß-NMN) that activates the PINK1-Parkin pathway, could alleviate TBBPA-induced mitophagy deficiency and further reduce the neuronal cytotoxicity, demonstrating that TBBPA-induced PINK1-Parkin-mediated mitophagy deficiency contributed to the neuronal cytotoxicity. Furthermore, we found TBBPA caused the upregulation of Atf3 (activating transcription factor 3) gene transcription and expression levels, alongside reduced Pink1 levels; whereas enhanced Pink1 transcript levels were observed after ATF3 depletion even under TBBPA treatment, demonstrating TBBPA-induced overexpression of ATF3 should be responsible for the reduced PINK1 expression. Therefore, for the first time, here we demonstrate that TBBPA can inhibit PINK1-Parkin-mediated mitophagy via upregulating ATF3 expression, which further contributes to its neuronal cytotoxicity. This study should be able to improve our understanding of the mechanism of TBBPA-induced neuronal cytotoxicity.

Super-adsorbent microspheres based on a triallyl isocyanurate-maleic anhydride copolymer for the removal of organic pollutants from water.

Owing to the frequent occurrence of diclofenac sodium (DS) in fresh aquatic environments and its potential toxicity towards living organisms, the effective removal of DS has attracted worldwide attention. Herein, a green and efficient strategy to fabricate crosslinked microspheres with interconnected mesoporous structures and abundant adsorption active sites was developed. With this strategy, triallyl isocyanurate (TAIC)-maleic anhydride (MAH) copolymer microspheres (TMs) with a diameter of 1.19-1.35 µm were first prepared by self-stabilized precipitation (2SP) polymerization, and the TMs possess a large amount reactive anhydride groups (62.5-71.8 mol%), a specific surface area of 51.6-182.4 m2 g-1 and a mesoporous structure (average pore size: 3.4-3.8 nm). Then the TMs were further functionalized with polyethylenimine (PEI) to give rise to cationic microspheres (Cat-TMs), which showed excellent adsorption performance to DS with a rapid adsorption rate (reached equilibrium within 30 min), a very high equilibrium adsorption capacity (1421 mg g-1) and excellent recyclability. The pseudo-second-order model and Langmuir model were a good fit for the adsorption kinetic and isotherm process, respectively. Furthermore, due to the high cation density (4.291 mmol g-1) and excellent pH buffer capacity of Cat-TMs, the adsorption capacity can be maintained at a high level within the pH range of 6-10. The regenerated Cat-TMs showed only a slight loss (<5%) in the adsorption capacity even after 5 adsorption-desorption cycles. In short, Cat-TMs can be considered as a highly promising adsorbent for the rapid and ultra-efficient removal of anionic organic contaminants and have significant potential to be applied in wastewater treatment.

Facile Surface Functionalization of Cyclic Olefin Copolymer Film with Anhydride Groups for Protein Microarray Fabrication.

Immobilization of protein at high efficiency is a challenge for fabricating polymer-based protein chips. Here, a simple but effective approach was developed to fabricate a cyclic olefin copolymer (COC)-based protein microarray with a high immobilization density. In this strategy, poly(maleic anhydride-co-vinyl acetate) (poly(MAH-co-VAc)) brushes were facilely attached on the COC surface via UV-induced graft copolymerization. The introduction of poly(MAH-co-VAc) brushes resulted in an obvious increase in the surface roughness of COC. The functionalized COC showed little reduction in transparency compared with pristine COC, indicating that the photografting treatment did not alter its optical property. The graft density of the anhydride groups on the modified COC could be tuned from 0.46 to 3.2 µmol/cm2. The immobilization efficiency of immunoglobulin G (IgG) on functionalized COC reached 88% due to the high reactivity between anhydride groups and amine groups of IgGs. An immunoassay experiment demonstrated that the microarray showed high sensitivity to the target analyte.

Layered Co-Immobilization of ß-Glucosidase and Cellulase on Polymer Film by Visible-Light-Induced Graft Polymerization.

Exploring a suitable immobilization strategy to improve catalytic efficiency and reusability of cellulase is of great importance to lowering the cost and promoting the industrialization of cellulose-derived bioethanol. In this work, a layered structure with a thin PEG hydrogel as the inner layer and sodium polyacrylate (PAANa) brush as the outer layer was fabricated on low density polyethylene (LDPE) film by visible-light-induced graft polymerization. Two enzymes, ß-glucosidase (BG) and cellulase, were separately coimmobilized onto this hierarchical film. As supplementary to cellulase for improving catalytic efficiency, BG was in situ entrapped into the inner PEG hydrogel layer during the graft polymerization from the LDPE surface. After graft polymerization of sodium acrylate on the PEG hydrogel layer was reinitiated, cellulase was covalently attached on the outer PAANa brush layer. Owing to the mild reaction condition (visible-light irradiation and room temperature), the immobilized BG could retain a high activity after the graft polymerization. The immobilization did not alter the optimal pH and temperature of BG or the optimal temperature of cellulase. However, the optimal pH of cellulase shifts to 5.0 after immobilization. Compared with the original activity of single cellulase system and isolated BG/cellulase immobilization system, the dual-enzyme system exhibited 82% and 20% increase in catalytic activity, respectively. The dual-enzyme system could maintain 93% of carboxymethylcellulose sodium salt (CMC) activity after repeating 10 cycles of hydrolysis and 89% of filter paper activity after 6 cycles relative to original activity, exhibiting excellent reusability. This layer coimmobilization system of BG and cellulase on the polymer film displays tremendous potential for practical application in a biorefinery.

[Investigation on snails Achatina fulica and Pomacea canaliculata infected with Angiostrongylus cantonensis in Panyu region of Guangzhou City].

OBJECTIVE: To understand the natural infection status of Angiostrongylus cantonensis in snails Achatina fulica and Pomacea canaliculata from Panyu region of Guangzhou City. METHODS: The snails Achatina fulica and Pomacea canaliculata captured from the field were digested with the artificial stomach fluid. The third-stage larvae of A. cantonensis were examined and counted under a microscope. The collected third-stage larvae were used to infect SD rats. RESULTS: A total of 367 Achatina fulica and 357 Pomacea canaliculata were examined. The infection rate of A. cantonensis in Achatina fulica was 22.62%, with a mean intensity of 57.00 larvae per positive snail. The infection rate of A. cantonensis in Pomacea canaliculata was 3.08%, with a mean intensity of 1.64 larvae per positive snail. The infection rates of A. cantonensis in Achatina fulica from Dagang, Shiqi, Hualong, and Lanhe towns and Nansha District, were 13.33%, 15.00%, 20.93%, 73.68% and 8.41%, respectively. Those in Pomacea canaliculata were 5.88%, 2.88%, 1.89%, 0% and 3.96%, respectively. CONCLUSIONS: A. cantonensis infection exists in Achatina fulica and Pomacea canaliculata from Panyu region of Guangzhou City, and the infection in Achatina fulica is more serious than that in Pomacea canaliculata. The infection rates of the snails among five sites are different.