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Oxygen sensing

Ana Morales-Menchén, Federico Navarro-García, José P Guirao-Abad, Elvira Román, Daniel Prieto, Ioana V Coman, Jesús Pla, Rebeca Alonso-Monge
Certain yeasts secrete peptides known as killer toxins or mycocins with a deleterious effect on sensitive yeasts or filamentous fungi, a common phenomenon in environmental species. In a recent work, different Debaryomyces hansenii ( Dh ) strains isolated from a wide variety of cheeses were identified as producing killer toxins active against Candida albicans and Candida tropicalis . We have analyzed the killer activity of these toxins in C. albicans mutants defective in MAPK signaling pathways and found that the lack of the MAPK Hog1 (but not Cek1 or Mkc1) renders cells hypersensitive to Dh mycocins while mutants lacking other upstream elements of the pathway behave as the wild type strain...
2018: Frontiers in Cellular and Infection Microbiology
Masahito Asada, Hassan Hakimi, Shin-Ichiro Kawazu
In recent years, genetically encoded fluorescent probes have allowed a dramatic advancement in time-lapse imaging, enabling this imaging modality to be used to investigate intracellular events in several apicomplexan parasite species. In this study, we constructed a plasmid vector to stably express a genetically encoded H2 O2 sensor probe called HyPer in Babesia bovis. The HyPer-transfected parasite population was successfully developed and subjected to a time-lapse imaging analysis under in vitro culture conditions...
May 15, 2018: Veterinary Parasitology
Ying Shi, Li Liu, Yuanyuan Yu, Yijuan Long, Huzhi Zheng
Nanomaterials have triggered tremendous interest to mimick peroxidase but rarely attention has been paid to small molecules. Herein we first found that acidic amino acids including l-glutamic acid (L-Glu) and l-aspartic acid (L-Asp) exhibited an intrinsic peroxidase-like activity, endowing acidic amino acids with the capability of catalysing the oxidation of the peroxidase substrates 3,3',5,5'-tetramethylbenzidine (TMB) to produce color reaction in the presence of H2 O2 . Reaction mechanism was further investigated by means of electron spin resonance spectroscopy (ESR), enzyme kinetics assay and quantum theoretical calculations, to verify and provide a good deal of insight into the catalytic process...
May 8, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Zhuang Lv, Liang Zou, Huanjie Wei, Shujuan Liu, Wei Huang, Qiang Zhao
It is very meaningful to develop bifunctional therapeutic agents which can monitor the tumor hypoxia in real time as well as maintain good photodynamic therapy (PDT) effect under hypoxia. To achieve it, herein, a series of hydrophilic phosphorescent starburst Pt(II) porphyrins as bifunctional therapeutic agents for simultaneous tumor hypoxia imaging and highly efficient PDT have been rationally designed and synthesized. They have been obtained by using Pt(II) porphyrins as the functional core and cationic oligofluorenes as the arms...
May 17, 2018: ACS Applied Materials & Interfaces
Gwyn A Beattie, Bridget M Hatfield, Haili Dong, Regina S McGrane
Plants collect, concentrate, and conduct light throughout their tissues, thus enhancing light availability to their resident microbes. This review explores the role of photosensing in the biology of plant-associated bacteria and fungi, including the molecular mechanisms of red-light sensing by phytochromes and blue-light sensing by LOV (light-oxygen-voltage)-domain proteins in these microbes. Bacteriophytochromes function as major drivers of the bacterial transcriptome and mediate light-regulated suppression of virulence, motility, and conjugation in some phytopathogens and light-regulated induction of the photosynthetic apparatus in a stem-nodulating symbiont...
May 16, 2018: Annual Review of Phytopathology
Gregory M Palmer, Hengtao Zhang, Chen-Ting Lee, Husam Mikati, Joseph A Herbert, Marlee Krieger, Jesko von Windheim, Dave Koester, Daniel Stevenson, Daniel J Rocke, Ramon Esclamado, Alaatin Erkanli, Nirmala Ramanujam, Mark W Dewhirst, Walter T Lee
Diffuse reflectance spectroscopy (DRS) represents a quantitative, noninvasive, nondestructive means of assessing vascular oxygenation, vascularity, and structural properties. However, it is known that such measurements can be influenced by the effects of pressure, which is a major concern for reproducible and operator-independent assessment of tissues. Second, regular calibration is a necessary component of quantitative DRS to account for factors such as lamp decay and fiber bending. Without a means of reliably controlling for these factors, the accuracy of any such assessments will be reduced, and potentially biased...
May 2018: Journal of Biomedical Optics
Rukiye Ayranci, Fatma Ozturk Kirbay, Dilek Odaci Demirkol, Metin Ak, Suna Timur
Simple, rapid and effective fluorescence sensing platform have been fabricated using fluorescent conducting polymer surface. For this purpose, a rhodamine based electroactive monomer (RDC) and a functional group containing monomer (SNS) have been copolymerized to develop a conducting polymer based sensor platform having a fluorescence and enzyme-binding surface on ITO electrode. The proposed fluorescence sensing mechanism for detection glucose is related to the consumption of dissolved oxygen at double layer of the electrode which is fluorescence quenching agent by glucose-GOx reaction...
May 16, 2018: Methods and Applications in Fluorescence
Jaehoon Jeong, Makram Essafi, Chulyeon Lee, Meriam Haoues, Mohamed Fethi Diouani, Hwajeong Kim, Youngkyoo Kim
Here we report that superoxide, one of the hazardous reactive oxygen species (ROS), can be quickly detected by flexible organic field-effect transistors (OFETs) with the polyphenol-embedded conjugated polymer micro-channels. Rutin, one of the abundant polyphenols found in a variety of plants, was employed as a sensing molecule and embedded in the poly(3-hexylthiophene) (P3HT) matrix. The rutin-embedded P3HT layers showed randomly distributed micro-domains, which became bigger as the rutin content increased...
April 27, 2018: Journal of Hazardous Materials
Sergio Colangiuli, Ana Rodríguez, María Ángeles Sanromán, Francisco J Deive
The definition of halophiles as "the coming stars of industrial biotechnology" in a recent review demands new research efforts for their efficient production at bioreactor scale. In this sense, the scarcity of information about halolipases production has furthered the research on the viability of Halomonas sp. LM1C culture in a mechanically stirred bioreactor. The operating conditions have been optimized by means of a Central Composite Face-Centered (CCFC) design. The operation at low aerations (0...
May 4, 2018: Bioresource Technology
Charles W Hespen, Joel J Bruegger, Yirui Guo, Michael A Marletta
Heme nitric oxide/oxygen sensing (H-NOX) domains are direct NO sensors that regulate a variety of biological functions in both bacteria and eukaryotes. Previous work on H-NOX proteins has shown that upon NO binding, a conformational change occurs along two glycine residues on adjacent helices (termed the glycine hinge). Despite the apparent importance of the glycine hinge, it is not fully conserved in all H-NOX domains. Several H-NOX sensors from the family Flavobacteriaceae contain a native alanine substitution in one of the hinge residues...
May 14, 2018: ACS Chemical Biology
E R Taylor
If extraterrestrials exist in the depths of cosmic space, and are capable of interstellar communications, even space flight, there is no requirement that they be humanoid in form. However, certain humanoid capabilities would be advantageous for tool fashioning and critical to operating space craft as well as functioning under the disparate extreme conditions under which they may be forced to operate. They would have to be "gas breathing". The reasonable assumption that life based upon the same elements as Earth life requiring water stems from the unique properties of water that no other similar low molecular weight nonmetal hydride offers...
May 2018: Life Sciences in Space Research
Tetsuhiro Tanaka, Kai-Uwe Eckardt
Cardiovascular disease is a common and serious complication in patients with chronic kidney disease (CKD). One of the fundamental functions of the cardiovascular system is oxygen delivery, therefore cardiovascular disease inherently is linked to insufficient tissue oxygenation. Advances in our knowledge of cellular oxygen sensing by a family of prolyl hydroxylases (PHDs) and their role in regulating hypoxia-inducible factors (HIFs) have led to the discovery of PHD inhibitors as HIF stabilizers. Several small-molecule PHD inhibitors are currently in clinical trials for the treatment of anemia in CKD...
May 2018: Seminars in Nephrology
Jamila Boudaden, Matthias Steinmaßl, Hanns-Erik Endres, Andreas Drost, Ignaz Eisele, Christoph Kutter, Peter Müller-Buschbaum
The development of humidity sensors with simple transduction principles attracts considerable interest by both scientific researchers and industrial companies. Capacitive humidity sensors, based on polyimide sensing material with different thickness and surface morphologies, are prepared. The surface morphology of the sensing layer is varied from flat to rough and then to nanostructure called nanograss by using an oxygen plasma etch process. The relative humidity (RH) sensor selectively responds to the presence of water vapor by a capacitance change...
May 11, 2018: Sensors
Eda Aydindogan, Emine Guler Celik, Dilek Odaci Demirkol, Shuhei Yamada, Takeshi Endo, Suna Timur, Yusuf Yagci
A novel catechol bearing polypeptide (CtP) was synthesized and used as a component of electrochemical biosensor involving both enzymatic activity and affinity-based sensing systems. Glucose oxidase (GOx) and Anti-Immunoglobulin G (Anti-IgG) were selected as model biorecognition elements for the selective analysis of glucose and IgG. Step by step surface modifications were followed using various techniques such as cyclic voltammetry (CV) and electrochemical impedance spectrometry (EIS) as well as X-Ray photoelectron spectroscopy (XPS)...
May 11, 2018: Biomacromolecules
Jan-Marino Ramirez, Liza Severs, Sanja C Ramirez, Ibis M Agosto-Marlin
Mammals must continuously regulate the levels of O2 and CO2 , which is particularly important for the brain. Failure to maintain adequate O2 /CO2 homeostasis has been associated with numerous disorders including sleep apnea, Rett syndrome, and sudden infant death syndrome (SIDS). But, O2 /CO2 homeostasis poses major regulatory challenges, even in the healthy brain. Neuronal activities change in a differentiated, spatially and temporally complex manner, which is reflected in equally complex changes in O2 demand...
May 9, 2018: Journal of Physiology
C Bento
INTRODUCTION: Congenital Erythrocytosis (CE) represents a rare and heterogeneous clinical entity. It is caused by deregulated erythropoiesis where red blood cell overproduction results in elevated hemoglobin and hematocrit levels. CE may either be primary or secondary to elevated erythropoietin concentrations. The only known form of primary CE is caused by mutations in the EPOR gene. Secondary CE can be a consequence of tissue hypoxia, being caused by congenital defects such as hemoglobin variants with increased oxygen affinity, due to mutations in the α- or β-globin genes (HBB, HBA2, HBA1), or due to mutations in the BPGM gene...
May 2018: International Journal of Laboratory Hematology
Khaled A Selim, Florian Haase, Marcus D Hartmann, Martin Hagemann, Karl Forchhammer
Cyanobacteria are phototrophic prokaryotes that evolved oxygenic photosynthesis ∼2.7 billion y ago and are presently responsible for ∼10% of total global photosynthetic production. To cope with the evolutionary pressure of dropping ambient CO2 concentrations, they evolved a CO2 -concentrating mechanism (CCM) to augment intracellular inorganic carbon (Ci ) levels for efficient CO2 fixation. However, how cyanobacteria sense the fluctuation in Ci is poorly understood. Here we present biochemical, structural, and physiological insights into SbtB, a unique PII -like signaling protein, which provides new insights into Ci sensing...
May 7, 2018: Proceedings of the National Academy of Sciences of the United States of America
A Damm, E Paul-Limoges, E Haghighi, C Simmer, F Morsdorf, F D Schneider, C van der Tol, M Migliavacca, U Rascher
Vegetation is a highly dynamic component of the Earth surface and substantially alters the water cycle. Particularly the process of oxygenic plant photosynthesis determines vegetation connecting the water and carbon cycle and causing various interactions and feedbacks across Earth spheres. While vegetation impacts the water cycle, it reacts to changing water availability via functional, biochemical and structural responses. Unravelling the resulting complex feedbacks and interactions between the plant-water system and environmental change is essential for any modelling approaches and predictions, but still insufficiently understood due to currently missing observations...
April 25, 2018: Journal of Plant Physiology
Chi Kwan Tsang, Miao Chen, Xin Cheng, Yanmei Qi, Yin Chen, Ishani Das, Xiaoxing Li, Brinda Vallat, Li-Wu Fu, Chao-Nan Qian, Hui-Yun Wang, Eileen White, Stephen K Burley, X F Steven Zheng
Nutrients are not only organic compounds fueling bioenergetics and biosynthesis, but also key chemical signals controlling growth and metabolism. Nutrients enormously impact the production of reactive oxygen species (ROS), which play essential roles in normal physiology and diseases. How nutrient signaling is integrated with redox regulation is an interesting, but not fully understood, question. Herein, we report that superoxide dismutase 1 (SOD1) is a conserved component of the mechanistic target of rapamycin complex 1 (mTORC1) nutrient signaling...
May 3, 2018: Molecular Cell
Caroline A Kelly, Malco Cruz-Romero, Joseph P Kerry, Dmitri P Papkovsky
The commercially-available optical oxygen-sensing system Optech-O₂ Platinum was applied to nondestructively assess the in situ performance of bulk, vacuum-packaged raw beef in three ~300 kg containers. Twenty sensors were attached to the inner surface of the standard bin-contained laminate bag (10 on the front and back sides), such that after filling with meat and sealing under vacuum, the sensors were accessible for optical interrogation with the external reader device. After filling and sealing each bag, the sensors were measured repetitively and nondestructively over a 15-day storage period at 1 °C, thus tracking residual oxygen distribution in the bag and changes during storage...
May 2, 2018: Sensors
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