An atypical GdpP enzyme linking cyclic nucleotide metabolism to osmotic tolerance and gene regulation in Mycoplasma bovis

Nucleotide second messengers play an important role in bacterial adaptation to environmental changes. Recent evidence suggests that some of these regulatory molecular pathways were conserved upon the degenerative evolution of the wall-less mycoplasmas. We have recently reported the occurrence of a phosphodiesterase (PDE) in the ruminant pathogen Mycoplasma bovis, which was involved in c-di-AMP metabolism. In the present study, we demonstrate that the genome of this mycoplasma species encodes a PDE of the GdpP family with atypical DHH domains. Characterization of M. bovis GdpP (MbovGdpP) revealed a multifunctional PDE with unusual nanoRNase and single-stranded DNase activities. The alarmone ppGpp was found unable to inhibit c-di-NMP degradation by MbovGdpP but efficiently blocked its nanoRNase activity. Remarkably, MbovGdpP was found critical for the osmotic tolerance of M. bovis under K+ and Na+ conditions. Transcriptomic analyses further revealed the biological importance of MbovGdpP in tRNA biosynthesis, pyruvate metabolism, and several steps in genetic information processing. This study is an important step in understanding the role of PDE and nucleotide second messengers in the biology of a minimal bacterial pathogen

Application as absorbents of natural and functionalized Brazilian bentonite in Pb2+ adsorption: Equilibrium, kinetic, pH, and thermodynamic effects

AbstractThe capacities of natural and modified Brazilian bentonite samples as adsorbents to remove lead were investigated under several conditions in batch and column methods. The raw material, natural bentonite, was modified by anchorament of 3-aminopropyltrietoxisilane (APS) and 3,2-aminoethylaminopropyltrimetoxisilane (AEAPS) in the surface of component minerals of bentonite sample. Adsorption behavior of three bentonite types was strongly depending on pH of adsorbate solution, contact time adsorbent/adsorbate, and initial concentration of metal. The maximum adsorption capacities of bentonite types were 20.6843, 27.6524, and 29.5413mgg−1 for natural, bentonite functionalized by APS, and bentonite functionalized by AEAPS, respectively. The results were confirmed by column method and show that the adsorption process of materials accorded with Sips and Langmuir isotherm models. The pseudo-second-order model simulation was also introduced to reveal the principles of the lead removal. The exothermic enthalpic values reflected a favorable energetic process for lead atoms anchored in the material surfaces. The original and modified bentonite samples were characterized by elemental analysis, scanning electron microscopy, and X-ray diffraction powder. The negative Gibbs free energy results supported the spontaneity of three adsorption reactions with Pb2+

Design of mine-used intrinsically safe wireless through-the-earth communication system

The paper introduced structure and key technologies of mine-used intrinsically safe wireless through-the-earth communication system，and analyzed working principle of the system. The system uses low-frequency electromagnetic radiation technology, digital communication technology and intrinsically safe power supply technology, which has characteristics of smaller volume, lighter weight and easy operation. The test results of prototype show that the system has realized two-way through-the-earth communication for 50 m with communication rate of about 150 bit/s and bit error rate of no larger than 0.2 %, and has a certain practical valu

Fabriction of ZnO Nanorods with Strong UV Absorption and Different Hydrophobicity on Foamed Nickel under Different Hydrothermal Conditions

ZnO nanorods have been grown on the surface of foamed nickel by a two-step method. Firstly, a layer of ZnO seed is sputtered on the surface of the foamed nickel by magnetron sputtering, and then the hydrothermal method is used to grow ZnO nanorods at different conditions (solution concentration, reaction time and reaction temperature). The results show that the morphology of ZnO nanorods is closely related to the solution concentration, reaction time, and reaction temperature. The energy band structure formed by the foamed nickel and ZnO seed layers and the growth mechanism of ZnO nanorods are discussed. The samples are characterized by Energy dispersive spectrometer (EDS), X-ray diffraction (XRD), and Raman spectroscopy. The absorption characteristics of samples to light are characterized by ultraviolet-to-visible (UV⁻VIS) absorption. The hydrophilicity of the samples is characterized by the static contact angle. By analyzing the performance characteristics of the samples at different conditions, we finally obtained the optimal growth parameters. At the optimal parameters, the morphology of the grown nanorods is regular, the ultraviolet band has strong absorption, and the surface of the samples forms a superhydrophobic surface

Antinociceptive effects of AGAP, a recombinant neurotoxic polypeptide: Possible involvement of the tetrodotoxin-resistant sodium channels in small dorsal root ganglia neurons

Antitumor-analgesic peptide（AGAP）is a novel recombinant polypeptide. The primary study showed that AGAP 1.0 mg/kg exhibited strong analgesic and antitumor effects. The tail vein administration of AGAP potently reduced pain behaviors in mice induced by intraplantar injection of formalin or intraperitoneal injection of acetic acid, without affecting basal pain perception. To further assess the mechanisms of AGAP, the effects of AGAP on sodium channels were assessed using the whole-cell patch clamp recordings in dorsal root ganglia (DRG) neurons. The results showed that AGAP (3-1000 nM) inhibited the sodium currents in small-diameter DRG neurons in a dose-dependent manner. 1000 nM AGAP could inhibit the current density-voltage relationship curve of sodium channels in a voltage-dependent manner and negatively shift the activation curves. 1000 nM AGAP could reduce the tetrodotoxin-resistant (TTX-R) sodium currents by 42.8% in small-diameter DRG neurons. Further analysis revealed that AGAP potently inhibited NaV1.8 currents by 59.4%, and negatively shifted the activation and inactivation kinetics. 1000 nM AGAP also reduced the NaV1.9 currents by 33.7%, but had no significant effect on activation and inactivation kinetics. Thus, our results demonstrated that submicromolar concentrations of AGAP inhibited TTX-R sodium channel in rat small-diameter DRG neurons. It is concluded that these new results may better explain, at least in part, the analgesic properties of this polypeptide

High Quality Factor, High Sensitivity Metamaterial Graphene—Perfect Absorber Based on Critical Coupling Theory and Impedance Matching

By means of critical coupling and impedance matching theory, we have numerically simulated the perfect absorption of monolayer graphene. Through the critical coupling effect and impedance matching, we studied a perfect single-band absorption of the monolayer graphene and obtained high quality factor (Q-factor = 664.2) absorption spectrum which has an absorbance close to 100% in the near infrared region. The position of the absorption spectrum can be adjusted by changing the ratio between the radii of the elliptic cylinder air hole and the structural period. The sensitivity of the absorber can be achieved S = 342.7 nm/RIU (RIU is the per refractive index unit) and FOM = 199.2 (FOM is the figure of merit), which has great potential for development on biosensors. We believe that our research will have good application prospects in graphene photonic devices and optoelectronic devices

Fabrication of ZnO@Ag@Ag3PO4 Ternary Heterojunction: Superhydrophilic Properties, Antireflection and Photocatalytic Properties

A ZnO seed layer was formed on the fluorine-doped tin oxide substrate by magnetron sputtering, and then a ZnO nanorod was grown on the ZnO seed layer by a hydrothermal method. Next, we prepared a single-crystal Ag seed layer by magnetron sputtering to form a ZnO@Ag composite heterostructure. Finally, Ag3PO4 crystals were grown on the Ag seed layer by a stepwise deposition method to obtain a ZnO@Ag@Ag3PO4 ternary heterojunction. The composite heterostructure of the material has super strong hydrophilicity and can be combined with water-soluble pollutants very well. Besides, it has excellent anti-reflection performance, which can absorb light from all angles. When Ag exists in the heterojunction, it can effectively improve the separation of photo-generated electrons and holes, and improve the photoelectric conversion performance. Based on the above characteristics, this nano-heterostructure can be used in the fields of solar cells, sensors, light-emitting devices, and photocatalysis