Does reduced usage of antibiotics in livestock production mitigate the spread of antibiotic resistance in soil, earthworm guts, and the phyllosphere?

The overuse of antibiotics in animal husbandry is widespread and believed to significantly contribute to the selection of antibiotic resistance genes (ARGs) in animals. Thus, there is a global drive to reduce antibiotic use in the agricultural sector. However, it has not been established whether a reduction in the use of antibiotics in livestock production would be effective in reducing the spread of ARGs. A microcosm approach was used to determine how the addition of manure with either reduced antibiotic levels or with typical antibiotic levels could affect the spread of antibiotic resistance genes between soil, earthworms and the phyllosphere. When compared to the control soil, earthworm and phyllosphere samples had the greater increase in ARG abundance in conventional manure treatments (P < 0.05). Reduced antibiotic manure also enriched the abundance of ARGs in the phyllosphere and soil but not earthworm guts when compared to the control (P < 0.05). In both soil and earthworm guts, the enrichment of ARGs was lower in reduced antibiotic manure than in conventional manure. This study has identified bacterial transfer through the soil-earthworm-phyllosphere system as a potential means to spread ARGs between habitats after fertilization with livestock derived manures

catena-Poly[diaqua­tris(μ3-biphenyl-2,2-dicarboxyl­ato)disamarium(III)]

The title compound, [Sm2(C14H8O4)3(H2O)2]n, is composed of one-dimensional chains and is isostructural with previously reported compounds [Wang et al. (2003 ▶). Eur. J. Inorg. Chem. pp. 1355–1360]. The asymmetric unit contains two Sm atoms, each of which lies on a crystallographic twofold axis. Both crystallographically independent Sm atoms are coordinated by eight O atoms in a distorted dodeca­hedral arrangement. The polymeric chains run along [001]. Adjacent chains are connected through π–π inter­actions [centroid–centroid distance = 3.450 (2) Å], forming a two-dimensional supra­molecular network

Poly[[tetra­aqua­bis[μ4-2,2′-(p-phenyl­ene­di­oxy)diacetato][μ2-2,2′-(p-phenyl­ene­di­oxy)diacetato]dierbium(III)] hexa­hydrate]

The asymmetric unit of the title compound, [Er2(C10H8O6)3(H2O)4]·6H2O, comprises one Er3+ ion, one and a half 2,2′-(p-phenyl­enedi­oxy)diacetate (hqda) ligands, two coordinated water mol­ecules and three uncoordinated water mol­ecules. The Er3+ ion is nine-coordinated by seven O atoms from hqda ligands and two O atoms from water mol­ecules. In the title compound, there are two types of crystallographically independent ligands: one with an inversion center in the middle of the ligand is chelating on both ends of the ligand towards each one Er center; the other hqda ligands are bridging-chelating on one side, and bridging on the other end of the ligand. Two adjacent Er3+ ions are thus chelated and bridged by –COO groups from hqda ligands in three coordination modes (briding–chelating, bridging and chelating). These building blocks are linked by OOC—CH2O—C6H4—OCH2—COO spacers, forming two-dimensional neutral layers. Adjacent layers are linked by O—H⋯O hydrogen-bonding inter­actions, forming a three-dimensional supermolecular network

Observation of Majorana fermions with spin selective Andreev reflection in the vortex of topological superconductor

Majorana fermion (MF) whose antiparticle is itself has been predicted in condensed matter systems. Signatures of the MFs have been reported as zero energy modes in various systems. More definitive evidences are highly desired to verify the existence of the MF. Very recently, theory has predicted MFs to induce spin selective Andreev reflection (SSAR), a novel magnetic property which can be used to detect the MFs. Here we report the first observation of the SSAR from MFs inside vortices in Bi2Te3/NbSe2 hetero-structure, in which topological superconductivity was previously established. By using spin-polarized scanning tunneling microscopy/spectroscopy (STM/STS), we show that the zero-bias peak of the tunneling differential conductance at the vortex center is substantially higher when the tip polarization and the external magnetic field are parallel than anti-parallel to each other. Such strong spin dependence of the tunneling is absent away from the vortex center, or in a conventional superconductor. The observed spin dependent tunneling effect is a direct evidence for the SSAR from MFs, fully consistent with theoretical analyses. Our work provides definitive evidences of MFs and will stimulate the MFs research on their novel physical properties, hence a step towards their statistics and application in quantum computing.Comment: 4 figures 15 page

Vasorelaxant Effect of a New Hydrogen Sulfide-Nitric Oxide Conjugated Donor in Isolated Rat Aortic Rings through cGMP Pathway

Endothelium-dependent vasorelaxant injury leads to a lot of cardiovascular diseases. Both hydrogen sulfide (H2S) and nitric oxide (NO) are gasotransmitters, which play a critical role in regulating vascular tone. However, the interaction between H2S and NO in vasorelaxation is still unclear. ZYZ-803 was a novel H2S and NO conjugated donor developed by H2S-releasing moiety (S-propyl-L-cysteine (SPRC)) and NO-releasing moiety (furoxan). ZYZ-803 could time- and dose-dependently relax the sustained contraction induced by PE in rat aortic rings, with potencies of 1.5- to 100-fold greater than that of furoxan and SPRC. Inhibition of the generations of H2S and NO with respective inhibitors abolished the vasorelaxant effect of ZYZ-803. ZYZ-803 increased cGMP level and the activity of vasodilator stimulated phosphoprotein (VASP) in aortic rings, and those effects could be suppressed by the inhibitory generation of H2S and NO. Both the inhibitor of protein kinase G (KT5823) and the inhibitor of KATP channel (glibenclamide) suppressed the vasorelaxant effect of ZYZ-803. Our results demonstrated that H2S and NO generation from ZYZ-803 cooperatively regulated vascular tone through cGMP pathway, which indicated that ZYZ-803 had therapeutic potential in cardiovascular diseases

Regulation of Matrix Metalloproteinase-2 Secretion from Scleral Fibroblasts and Retinal Pigment Epithelial Cells by miR-29a

. Purpose. To identify an effective method to prevent myopia progression by characterizing the regulation of matrix metalloproteinase-(MMP-) 2 expression and its secretion from scleral fibroblasts and retinal pigment epithelium (RPE) cells by miR-29a. Methods. The effects of miR-29a on the growth of scleral fibroblasts and RPE cells were assessed using the cell counting kit-8. The changes in MMP-2 mRNA levels in scleral fibroblasts and RPE cells after transfection with miR-29a mimics or inhibitor were measured by quantitative PCR. Enzyme-linked immunosorbent assays were used to determine the changes in MMP-2 secretion from scleral fibroblasts and RPE cells after transfection with miR-29a mimics or inhibitor. Results. The miR-29a mimics or inhibitor did not significantly alter the growth of scleral fibroblasts or RPE cells at 24, 48, or 72 hours after transfection. MMP-2 mRNA levels were significantly decreased in scleral fibroblasts and RPE cells transfected with the miR-29a mimics. The secretion of MMP-2 by scleral fibroblasts and RPE cells was significantly decreased in cells transfected with the miR-29a mimics. Conclusions. Suppression of scleral fibroblast and RPE cell expression and secretion of MMP-2 by miR-29a can be used as a therapeutic target for the prevention and treatment of myopia

An ultra-sensitive and easy-to-use assay for sensing human UGT1A1 activities in biological systems

The human UDP-glucuronosyltransferase 1A1 (UGT1A1), one of the most essential conjugative enzymes, is responsible for the metabolism and detoxification of bilirubin and other endogenous substances, as well as many different xenobiotic compounds. Deciphering UGT1A1 relevance to human diseases and characterizing the effects of small molecules on the activities of UGT1A1 requires reliable tools for probing the function of this key enzyme in complex biological matrices. Herein, an easy-to-use assay for highly-selective and sensitive monitoring of UGT1A1 activities in various biological matrices, using liquid chromatography with fluorescence detection (LC-FD), has been developed and validated. The newly developed LC-FD based assay has been confirmed in terms of sensitivity, specificity, precision, quantitative linear range and stability. One of its main advantages is lowering the limits of detection and quantification by about 100-fold in comparison to the previous assay that used the same probe substrate, enabling reliable quantification of lower amounts of active enzyme than any other method. The precision test demonstrated that both intra- and inter-day variations for this assay were less than 5.5%. Furthermore, the newly developed assay has also been successfully used to screen and characterize the regulatory effects of small molecules on the expression level of UGT1A1 in living cells. Overall, an easy-to-use LC-FD based assay has been developed for ultra-sensitive UGT1A1 activities measurements in various biological systems, providing an inexpensive and practical approach for exploring the role of UGT1A1 in human diseases, interactions with xenobiotics, and characterization modulatory effects of small molecules on this conjugative enzyme. (c) 2020 Xi'an Jiaotong University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Peer reviewe

Long-Wavelength AIE-Based Fluorescent Probes for Mitochondria-Targeted Imaging and Photodynamic Therapy of Hepatoma Cells

With this research, we have developed two long-wavelength theranostic probes (DCMT and DCMC) with aggregation-induced emission (AIE)-based properties for image-guided photodynamic therapy (PDT) of hepatoma cells. Introduction of a triphenylamine or carbazole group to a dicyanomethylene-4H-pyran dye with long-wavelength fluorescence emission produces the AIE-based probes, which were subsequently modified with triphenyl-phosphonium cation for actively targeting the mitochondria of hepatoma cells. Solution-based experiments show that the probes exhibit a mixed photophysical mechanism of twisted-intramolecular charge transfer and AIE at different aggregation states. The molecular aggregation of the probes also leads to an enhanced ability for oxygen photosensitization, suggesting their potential for PDT of cancer cells. Our subsequent cell-based assays show that the probes localize in the mitochondria of hepatoma cells and the use of light leads to cell death through the intracellular production of reactive oxygen species. </p