Agdc1p - a gallic acid decarboxylase involved in the degradation of tannic acid in the yeast Blastobotrys (Arxula) adeninivorans

Tannins and hydroxylated aromatic acids, such as gallic acid (3,4,5-trihydroxybenzoic acid), are plant secondary metabolites which protect plants against herbivores and plant-associated microorganisms. Some microbes, such as the yeast Arxula adeninivorans are resistant to these antimicrobial substances and are able to use tannins and gallic acid as carbon sources. In this study, the Arxula gallic acid decarboxylase (Agdc1p) which degrades gallic acid to pyrogallol was characterized and its function in tannin catabolism analyzed. The enzyme has a higher affinity for gallic acid (Km -0.7 ± 0.2 mM, kcat -42.0 ± 8.2 s-1) than to protocatechuic acid (3,4-dihydroxybenzoic acid) (Km -3.2 ± 0.2 mM, kcat -44.0 ± 3.2 s-1). Other hydroxylated aromatic acids, such as 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid and 2,5-dihydroxybenzoic acid are not gallic acid decarboxylase substrates. A. adeninivorans G1212/YRC102-AYNI1-AGDC1, which expresses the AGDC1 gene under the control of the strong nitrate inducible AYNI1 promoter achieved a maximum gallic acid decarboxylase activity of 1064.4 U/l and 97.5 U/g of dry cell weight in yeast grown in minimal medium with nitrate as nitrogen source and glucose as carbon source. In the same medium, gallic acid decarboxylase activity was not detected for the control strain G1212/YRC102 with AGDC1 expression under the control of the endogenous promoter. Gene expression analysis showed that AGDC1 is induced by gallic acid and protocatechuic acid. In contrast to G1212/YRC102-AYNI1-AGDC1 and G1212/YRC102, A. adeninivorans G1234 [δagdc1] is not able to grow on medium with gallic acid as carbon source but can grow in presence of protocatechuic acid. This confirms that Agdc1p plays an essential role in the tannic acid catabolism and could be useful in the production of catechol and cis, cis-muconic acid. However, the protocatechuic acid catabolism via Agdc1p to catechol seems to be not the only degradation pathway

Fast, ultrasensitive detection of reactive oxygen species using a carbon nanotube based-electrocatalytic intracellular sensor

Herein, we report a highly sensitive electrocatalytic sensor-cell construct that can electrochemically communicate with the internal environment of immune cells (e.g., macrophages) via the selective monitoring of a particular reactive oxygen species (ROS), hydrogen peroxide. The sensor, which is based on vertically aligned single-walled carbon nanotubes functionalized with an osmium electrocatalyst, enabled the unprecedented detection of a local intracellular “pulse” of ROS on a short second time scale in response to bacterial endotoxin (lipopolysaccharide-LPS) stimulation. Our studies have shown that this initial pulse of ROS is dependent on NADPH oxidase (NOX) and toll like receptor 4 (TLR4). The results suggest that bacteria can induce a rapid intracellular pulse of ROS in macrophages that initiates the classical innate immune response of these cells to infection

Comparing the effectiveness of hyperspectral imaging and Raman spectroscopy:A case study on Armenian manuscripts

Additional file 1. Additional Figures S1–S5 and Tables S1, S2

Simulation of guided wave inspections using hybrid modal/finite element formulation: Application to a SHM system for pipe monitoring with complex geometries

Conference of 10th International Workshop on Structural Health Monitoring: System Reliability for Verification and Implementation, IWSHM 2015 ; Conference Date: 1 September 2015 Through 3 September 2015; Conference Code:115766International audienceModels for guided wave inspection are developed at CEA-LIST in the CIVA software platform. They are based on a numerical approach combining a modal description in regular parts of wave guides (plates, pipes, or guides of arbitrary crosssection like rails) and a Finite Element (FE) computation, in the vicinity of flaws or guide irregularities. It enables the simulation of the interaction of guided waves with complex defects such as a flaw of arbitrary shape, corrosion, delamination or cracks. This approach is applied here to various industrial configurations. Modes are computed thanks to the Semi-Analytical Finite Element (SAFE) method in each uniform portion of the waveguide, whereas a FE computation is performed in each region surrounding a defect or a local variation of waveguide shape. Several scattering matrices can then be associated in series in the frequency domain. This offers the possibility to deal with several defects in series. Finally, a mode matching technique has been recently used to get the scattering matrix of a complete pipe elbow. The different models are set in the frequency domain so an inverse Fourier transform is finally applied to determine the temporal signal measured by the sensor. A numerical study involving all these models is presented on a SHM system for pipe inspections in order to detect defects located after an elbow. Parametric studies are proposed in order to illustrate the simulation capabilities of this set of numerical tools

Transfer from Microorganisms to Electrodes for Green Electricity?

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Hybrid modal/fe simulation of guided waves inspections

39th Annual Review of Progress in Quantative Nondestructive Evaluation (QNDE), Denver, CO, JUL 15-20, 2012International audienceA hybrid numerical method coupling a modal description in regular parts of the waveguides and a Finite Element computation in the vicinity of guide perturbations has been developed several years ago. This approach enables the simulation of complex defects interaction and the computation of the wave field generated by a source located inside the waveguide or on its surface. A study combining generation and interaction of guided waves through a complex structure is presented

New models for ultrasonic guided wave inspections in CIVA

Conference of 52nd Annual Conference of the British Institute of Non-Destructive Testing 2013, BINDT 2013 ; Conference Date: 10 September 2013 Through 12 September 2013; Conference Code:107049International audienceModels for ultrasonic guided wave NDT are developed at CEA LIST and integrated into the CIVA platform. Models already available in CIVA 10 deal with plates and cylindrical guides, possibly multilayered. Mode computation, radiated field from different type of transducers (contact with or without wedge, surrounding or surrounded arrays in pipes) and response of a NDT examination in pulse-echo or pitch-catch configurations for a crack orthogonal to the guide axis are proposed. These models are now extended to deal with guides of arbitrary section with planar extrusion, modes being computed with the Semi-Analytical Finite Element (SAFE) method. A hybrid SAFE-Finite Element method has also been integrated to compute the response of a flaw of arbitrary shape, a weld or a complex junction. These new models as well as their validations are presented and discussed

New perspectives on iron uptake in eukaryotes

© 2018 Sherman, Jovanovic, Stolnik, Baronian, Downard and Rawson. All eukaryotic organisms require iron to function. Malfunctions within iron homeostasis have a range of physiological consequences, and can lead to the development of pathological conditions that can result in an excess of non-transferrin bound iron (NTBI). Despite extensive understanding of iron homeostasis, the links between the "macroscopic" transport of iron across biological barriers (cellular membranes) and the chemistry of redox changes that drive these processes still needs elucidating. This review draws conclusions from the current literature, and describes some of the underlying biophysical and biochemical processes that occur in iron homeostasis. By first taking a broad view of iron uptake within the gut and subsequent delivery to tissues, in addition to describing the transferrin and non-transferrin mediated components of these processes, we provide a base of knowledge from which we further explore NTBI uptake. We provide concise up-to-date information of the transplasma electron transport systems (tPMETSs) involved within NTBI uptake, and highlight how these systems are not only involved within NTBI uptake for detoxification but also may play a role within the reduction of metabolic stress through regeneration of intracellular NAD(P)H/NAD(P)+ levels. Furthermore, we illuminate the thermodynamics that governs iron transport, namely the redox potential cascade and electrochemical behavior of key components of the electron transport systems that facilitate the movement of electrons across the plasma membrane to the extracellular compartment. We also take account of kinetic changes that occur to transport iron into the cell, namely membrane dipole change and their consequent effects within membrane structure that act to facilitate transport of ions

Titanium tungsten coatings for bioelectrochemical applications

This paper presents an assessment of titanium tungsten (TiW) coatings and their applicability as components of biosensing systems. The focus is put on using TiW as an electromechanical interface layer between carbon nanotube (CNT) forests and silicon nanograss (SiNG) cell scaffolds. Cytotoxicity, applicability to plasma-enhanced chemical vapor deposition (PECVD) of aligned CNT forests, and electrochemical performance are investigated. Experiments include culturing of NIH3T3 mouse embryonic fibroblast cells on TiW coated silicon scaffolds, CNT growth on TiW substrates with nickel catalyst, and cyclic voltammetric investigation with PBS-buffered potassium hexacyanoferrate (II/III)