Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, 91198, Gif-sur-Yvette, France.
Published: September 2020
AI Article Synopsis
Article Abstract
Heavy metal contamination is a serious environmental problem. Understanding the toxicity mechanisms may allow to lower concentration of metals in the metal-based antimicrobial treatments of crops, and reduce metal content in soil and groundwater. Here, we investigate the interplay between metal efflux systems and the superoxide dismutase (SOD) in the purple bacterium Rubrivivax gelatinosus and other bacteria through analysis of the impact of metal accumulation. Exposure of the Cd -efflux mutant ΔcadA to Cd caused an increase in the amount and activity of the cytosolic Fe-Sod SodB, thereby suggesting a role of SodB in the protection against Cd . In support of this conclusion, inactivation of sodB gene in the ΔcadA cells alleviated detoxification of superoxide and enhanced Cd toxicity. Similar findings were described in the Cu -efflux mutant with Cu . Induction of the Mn-Sod or Fe-Sod in response to metals in other bacteria, including Escherichia coli, Pseudomonas aeruginosa, Pseudomonas putida, Vibrio cholera and Bacillus subtilis, was also shown. Both excess Cd or Cu and superoxide can damage [4Fe-4S] clusters. The additive effect of metal and superoxide on the [4Fe-4S] could therefore explain the hypersensitive phenotype in mutants lacking SOD and the efflux ATPase. These findings underscore that ROS defence system becomes decisive for bacterial survival under metal excess.
In this study, ex-situ catalytic pyrolysis of oxygen-containing polycarbonate (PC) was conducted to prepare carbon nanotubes (CNTs) and H-rich syngas. This study examined the influence of the active metal components (Ni and Fe), catalyst pre-reduction, and pre-deoxygenation of pyrolysis volatiles on the catalytic performance and mechanism. Results show that the reductive constituents in pyrolysis volatiles make it difficult to reduce the Fe oxides, thus hindering the CNTs growth on Fe catalysts, compared to Ni catalysts.
This paper describes the use of the layered conductive metal-organic framework (MOF) (nickel)-(hexahydroxytriphenylene) [Ni(HHTP)] as a model system for understanding the process of self-assembly within this class of materials. We confirm and quantify experimentally the role of the oxidant in the synthetic process. Monitoring the deposition of Ni(HHTP) with infrared spectroscopy revealed that MOF formation is characterized by an initial induction period, followed by linear growth with respect to time.
The cross talk and power consumption of the 2 × 2 optical switch is a key metric in the design of large-scale photonic integrated circuits (PICs). We build a theoretical model of a 2 × 2 Mach-Zehnder interferometer (MZI) optical switch, taking into account both imbalances in the arm loss and the coupler splitting ratio. The splitting ratio imbalance requirement for a given switch cross talk is summarized, which provides a guideline for the switch design.
University Lyon, Université Claude Bernard Lyon 1, CNRS UMR-5261, INSERM U-1315, Institut NeuroMyoGène - Pathophysiology and Genetics of Neuron and Muscle , Lyon, France.
The potential pathogenic role of disturbed Ca2+ homeostasis in Duchenne muscular dystrophy (DMD) remains a complex, unsettled issue. We used muscle fibers isolated from 3-mo-old DMDmdx rats to further investigate the case. Most DMDmdx fibers exhibited no sign of trophic or morphology distinction as compared with WT fibers and mitochondria and t-tubule membrane networks also showed no stringent discrepancy.
Zn-based biodegradable metals (BMs) are regarded as revolutionary biomaterials for bone implants. However, their clinical application is limited by insufficient mechanical properties, delayed degradation, and overdose-induced Zn toxicity. Herein, innovative multi-material additive manufacturing (MMAM) is deployed to construct a Zn/titanium (Ti) hetero-structured composite.
