Optimization of electrochemical regeneration of intercalated MXene for the adsorptive removal of ciprofloxacin: Prospective mechanism.

2D-Ti3C2Tx MXene nanosheets intercalated with sodium ions (SI-Ti3C2Tx) were synthesized and utilized in simultaneous adsorption and electrochemical regeneration with ciprofloxacin (CPX). The primary focus of this study is to investigate the long-term stability of SI-Ti3C2Tx MXene and to propose the underlying regeneration mechanisms. The successful synthesis of Ti3AlC2, Ti3C2Tx MXene, and SI-Ti3C2Tx MXene was confirmed using X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. Electrochemical regeneration parameters such as charge passed, regeneration time, current density, and electrolyte composition were optimized with values of 787.5 C g-1, 7.5 min, 10 mA cm-2, and 2.5w/v% sodium chloride, respectively, enabling the complete regeneration of the SI-Ti3C2Tx MXene. In addition, the electrochemical regeneration significantly enhanced CPX removal from the SI-Ti3C2Tx MXene owing to partial amorphization, disorderliness, increased functional groups, delamination, and defect creation in the structure. Thus, the synthesized nano-adsorbent has proven helpful in practical water treatment with optimized electrochemical regeneration processes.

Enhanced biodegradation of perfluorooctanoic acid in a dual biocatalyzed microbial electrosynthesis system.

The toxic perfluorooctanoic acid (PFOA) is widely spread in terrestrial and aquatic habitats owing to its resistance to conventional degradation processes. Advanced techniques to degrade PFOA requires drastic conditions with high energy cost. In this study, we investigated PFOA biodegradation in a simple dual biocatalyzed microbial electrosynthesis system (MES). Different PFOA loadings (1, 5, and 10 ppm) were tested and a biodegradation of 91% was observed within 120 h. Propionate production improved and short-carbon-chain PFOA intermediates were detected, which confirmed PFOA biodegradation. However, the current density decreased, indicating an inhibitory effect of PFOA. High-throughput biofilm analysis revealed that PFOA regulated the microbial flora. Microbial community analysis showed enrichment of the more resilient and PFOA adaptive microbes, including Methanosarcina and Petrimonas. Our study promotes the potential use of dual biocatalyzed MES system as an environment-friendly and inexpensive method to remediate PFOA and provides a new direction for bioremediation research.

Development of new tools to study membrane-anchored mammalian Atg8 proteins.

ABBREVIATIONS: A:C autophagic membrane:cytosol; ALS amyotrophic lateral sclerosis; ATG4 autophagy related 4; Atg8 autophagy related 8; BafA1 bafilomycin A1; BNIP3L/Nix BCL2 interacting protein 3 like; CALCOCO2/NDP52 calcium binding and coiled-coil domain 2; EBSS Earle's balanced salt solution; GABARAP GABA type A receptor-associated protein; GST glutathione S transferase; HKO hexa knockout; Kd dissociation constant; LIR LC3-interacting region; MAP1LC3/LC3 microtubule associated protein 1 light chain 3; NLS nuclear localization signal/sequence; PE phosphatidylethanolamine; SpHfl1 Schizosaccharomyces pombeorganic solute transmembrane transporter; SQSTM1/p62 SQSTM1/p62; TARDBP/TDP-43 TAR DNA binding protein; TKO triple knockout.

Apnoeic oxygenation using transnasal humidified rapid-insufflation ventilatory exchange during rigid bronchoscopy: a report of four cases.

General anaesthesia with a muscle relaxant is usually performed for rigid bronchoscopy (RB), but ventilation is challenging due to large amounts of leakage. Optiflow™ supplies 100% humidified, warmed oxygen at a rate of up to 70 l/min and this high flow rate may overcome the leakage problem. This case report describes four patients that were scheduled for RB. The lung lesions were all located below the carina, so a bronchial tube was inserted under general anaesthesia. Once a large amount of leakage was confirmed by manual ventilation, Optiflow™ was connected to the bronchial tube (flow rate, 70 l/min). All of the ports of the bronchoscopy were left open to prevent the risk of outlet obstruction. Oxygenation was well maintained with stable vital signs throughout the procedures, which took up to 34 min without airway intervention. There were no occurrences of cardiac arrhythmia or changes in the electrocardiograms. Respiratory acidosis recovered after emergence, which was confirmed by arterial blood gas analysis in all cases. Apnoeic oxygenation using Optiflow™ was applied successfully during RB. Applying Optiflow™ could make cases of difficult ventilation during RB much easier for the anaesthetist. Larger studies need to demonstrate the efficacy and safety of this technique.

LIR motifs and the membrane-targeting domain are complementary in the function of RavZ.

The bacterial effector protein RavZ is secreted by the intracellular pathogen Legionella pneumophila and inhibits host autophagy through an irreversible deconjugation of mammalian ATG8 (mATG8) proteins from autophagosome membranes. However, the roles of the LC3 interacting region (LIR) motifs in RavZ function remain unclear. In this study, we show that a membrane-targeting (MT) domain or the LIR motifs of RavZ play major or minor roles in RavZ function. A RavZ mutant that does not bind to mATG8 delipidated all forms of mATG8-phosphatidylethanolamine (PE) as efficiently as did wild-type RavZ. However, a RavZ mutant with a deletion of the MT domain selectively delipidated mATG8-PE less efficiently than did wild-type RavZ. Taken together, our results suggest that the effects of LIR motifs and the MT domain on RavZ activity are complementary and work through independent pathways. [BMB Reports 2019; 52(12): 700-705].

Monitoring LC3- or GABARAP-positive autophagic membranes using modified RavZ-based probes.

Xenophagy is a selective lysosomal degradation pathway for invading pathogens in host cells. However, invading bacteria also develop survival mechanisms to inhibit host autophagy. RavZ is a protein secreted by Legionella that irreversibly delipidates mammalian autophagy-related protein 8 (mATG8) on autophagic membranes in host cells via efficient autophagic membrane targeting. In this study, we leveraged the autophagic membrane-targeting mechanism of RavZ and generated a new autophagosome probe by replacing the catalytic domain of RavZ with GFP. This probe is efficiently localized to mATG8-positive autophagic membranes via a synergistic combination between mATG8 protein-binding mediated by the LC3-interacting region (LIR) motifs and phosphoinositide-3-phosphate (PI3P) binding mediated by the membrane-targeting (MT) domain. Furthermore, the membrane association activity of this new probe with an MT domain was more efficient than that of probes with a hydrophobic domain that were previously used in LIR-based autophagosome sensors. Finally, by substituting the LIR motifs of RavZ with selective LIR motifs from Fyco1 or ULK2, we developed new probes for detecting LC3A/B- or GABARAP subfamily-positive autophagic membranes, respectively. We propose that these new RavZ-based sensors will be useful for monitoring and studying the function of mATG8-positive autophagic membranes in different cellular contexts for autophagy research.

Development of GABARAP family protein-sensitive LIR-based probes for neuronal autophagy.

Autophagy allows for lysosomal cellular degradation of cytosolic components. In particular, neuronal autophagy is essential for cellular homeostasis and neuronal survival and is tightly regulated by several autophagy-related (ATG) proteins in post-mitotic neurons. Among these ATG proteins, the LC3/GABARAP proteins are known to regulate autophagosome biogenesis/maturation and cargo recognition. However, little is known about the role of GABARAP family proteins in neuronal autophagy despite their abundant expression in post-mitotic neurons. We have previously developed HyD (Hydrophobic Domain)-LIR (LC3-interacting region)-based autophagosome markers. In this study, to monitor GABARAP family proteins in autophagosomes of post-mitotic neurons, we improved the sensitivity of the probes for specifically detecting endogenous GABARAP family proteins by adding one more LIR motif to the LIR probes. We have tested the efficiency of two different LIRs, from ULK2 and Stbd1, in regard to their cellular localization to autophagosomes. HyD-2xLIR(ULK2)-GFP and HyD-2xLIR(Stbd1)-GFP demonstrated specific localization to GABARAP-positive autophagosomes relative to LC3B-positive autophagosomes in MEF/HeLa cells in an autophagy-dependent manner. Indeed, HyD-2xLIR(Stbd1)-GFP could efficiently detect GABARAP-positive autophagosomes in cultured cortical neurons. Our improved GABARAP-sensitive probes will contribute toward understanding the specific role of GABARAP family proteins in regard to neuronal autophagy.