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Oxygen sensing

Leandro P Ravaro, Tiago R Almeida, Rodrigo Q Albuquerque, Andrea S S de Camargo
The polynuclear complex Cu4I4py4 has been largely studied in solution and in the powder form due to its interesting luminescent properties, which are largely dependent on temperature and pressure. In this work, we present the synthesis of the complex and its wet impregnation in a mesoporous silica host obtained by sol-gel methodology. For optimized loadings, the well-dispersed guest molecules exhibit strong interaction with molecular oxygen, resulting in a significant quenching of the luminescence. The process is highly reversible with a Stern-Volmer constant of Ksv = 33...
October 17, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Natalie C Sadler, Hans C Bernstein, Matthew R Melnicki, Moiz A Charania, Eric A Hill, Lindsey N Anderson, Matthew E Monroe, Richard D Smith, Alexander S Beliaev, Aaron T Wright
: Photobiologically synthesized hydrogen (H2) gas is carbon-neutral to produce and clean to combust, making it an ideal biofuel. Cyanothece sp. ATCC 51142 is a cyanobacterium capable of performing simultaneous oxygenic photosynthesis and H2 production, a highly perplexing phenomenon because H2 evolving enzymes are O2-sensitive. We employed a systems-level in vivo chemoproteomic profiling approach to explore the cellular dynamics of protein thiol redox, and how thiol redox mediates the function of the dinitrogenase NifHDK, an enzyme complex capable of aerobic hydrogenase activity...
October 14, 2016: Applied and Environmental Microbiology
Marina Villanueva-Paz, Mario D Cordero, Ana Delgado Pavón, Beatriz Castejón Vega, David Cotán, Mario De la Mata, Manuel Oropesa-Ávila, Elizabet Alcocer-Gomez, Isabel de Lavera, Juan Garrido-Maraver, José Carrascosa, Ana Paula Zaderenko, Jordi Muntané, Manuel de Miguel, José Antonio Sánchez-Alcázar
Systemic treatments for hepatocellular carcinoma (HCC) have been largely unsuccessful. This study investigated the antitumoral activity of Amitriptyline, a tricyclic antidepressant, in hepatoma cells. Amitriptyline-induced toxicity involved early mitophagy activation that subsequently switched to apoptosis. Amitriptyline induced mitochondria dysfunction and oxidative stress in HepG2 cells. Amitriptyline specifically inhibited mitochondrial complex III activity that is associated with decreased mitochondrial membrane potential (∆Ψm) and increased reactive oxygen species (ROS) production...
July 2016: Genes & Cancer
Saiprasad Ramnarayanan, Chandrashekara Kyathanahalli, Judith Ingles, Miejung Park-York, Pancharatnam Jeyasuria, Jennifer C Condon
There is considerable evidence that implicates oxidative stress in the pathophysiology of human pregnancy complications. However the role and the mechanism of maintaining an anti-oxidant pro-survival uterine environment during normal pregnancy is largely unresolved. Herein we report the highly active uterine unfolded protein response plays a key role in promoting anti-oxidant activity in the uterine myocyte across gestation. The unfolded protein response senses the accumulation of misfolded proteins in the endoplasmic reticulum (ER) and activates a signaling network that consists of the transmembrane protein kinase eukaryotic translation initiation factor 2 alpha kinase 3/PKR-like-ER kinase (EIF2AK3), which acts to decrease protein translation levels allowing for a lowered need for protein folding during periods of ER stress...
October 12, 2016: Biology of Reproduction
Daniel Gruneberg, Felipe A Montellano, Konstanze Plaschke, Lexiao Li, Hugo H Marti, Reiner Kunze
Episodes of cerebral hypoxia/ischemia increase the risk of dementia, which is associated with impaired learning and memory. Previous studies in rodent models of dementia indicated a favorable effect of the hypoxia-inducible factor (HIF) targets VEGF (vascular endothelial growth factor) and erythropoietin (Epo). In the present study we thus investigated whether activation of the entire adaptive HIF pathway in neurons by cell-specific deletion of the HIF suppressor prolyl-4-hydroxylase 2 (PHD2) improves cognitive abilities in young (3months) and old (18-28months) mice suffering from chronic brain hypoperfusion...
October 5, 2016: Experimental Neurology
S F A Rahman, N A Yusof, U Hashim, R Hushiarian, M Nuzaihan M N, M N Hamidon, R M Zawawi, M F M Fathil
Dengue Virus (DENV) has become one of the most serious arthropod-borne viral diseases, causing death globally. The existing methods for DENV detection suffer from the late stage treatment due to antibodies-based detection which is feasible only after five days following the onset of the illness. Here, we demonstrated the highly effective molecular electronic based detection utilizing silicon nanowire (SiNW) integrated with standard complementary metal-oxide-semiconductor (CMOS) process as a sensing device for detecting deoxyribonucleic acid (DNA) related to DENV in an early stage diagnosis...
October 26, 2016: Analytica Chimica Acta
Doron Shkolnik, Hillel Fromm
Optimization of water foraging by plants is partially achieved by the ability of roots to direct growth towards high water potential, a phenomenon termed hydrotropism. In contrast to gravitropism and phototropism, which require auxin redistribution, as suggested by the Cholodny-Went theory, hydrotropism is not mediated by the phytohormone auxin, which raises questions about the mechanism underlying this tropic response. Here we specify the open questions in this field of research and discuss the possible interactions of abscisic acid, calcium and reactive oxygen species as part of a dynamic system of sensing water potential in the root tip, transmission of the signal to the root elongation zone and promoting root curvature towards water...
November 2016: Plant Science: An International Journal of Experimental Plant Biology
Do-Kyun Kwon, Su Jeong Lee, Jae-Min Myoung
In this work, vertically aligned zinc oxide (ZnO) nanorod (NR)-based flexible ultraviolet (UV) photodetectors were successfully fabricated on a polyimide (PI) substrate with a copper (Cu) nanowire (NW) electrode. To enhance the flexibility and sensing properties, the entangled networks of Cu NWs were applied to UV photodetectors as a flexible electrode. Here, Cu NWs have a high conductivity with a low cost compared to other metals to achieve a Schottky contact with ZnO NRs. Moreover, because of forming a network structure, the surface of the sensing material has a large contact area with oxygen molecules, resulting in a faster response time...
September 22, 2016: Nanoscale
Tino Colombi, Serge Braun, Thomas Keller, Achim Walter
The structure of compacted soils is characterised by decreased (macro-)porosity, which leads to increased mechanical impedance and decreased fluid transport rates, resulting in reduced root growth and crop productivity. Particularly in soils with high mechanical impedance, macropores can be used by roots as pathways of least resistance. This study investigated how different soil physical states relate to whole plant growth and whether roots grow towards spots with favourable soil physical conditions. Experiments were conducted under controlled and field conditions...
October 3, 2016: Science of the Total Environment
(no author information available yet)
Gregg L. Semenza, MD, PhD; Peter J. Ratcliffe, MD; and William G. Kaelin Jr., MD, will share the 2016 Albert Lasker Basic Medical Research Award. Bestowed by the Lasker Foundation, the award recognizes their discovery of the pathway that cells use to sense and adapt to changes in availability of oxygen. Such changes can play a role in cancer progression and the development of other medical conditions.
October 5, 2016: Cancer Discovery
Di Yan, Christian Domes, Robert Domes, Timea Frosch, Jürgen Popp, Mathias W Pletz, Torsten Frosch
Fiber enhanced resonance Raman spectroscopy (FERS) is introduced for chemically selective and ultrasensitive analysis of the biomolecules hematin, hemoglobin, biliverdin, and bilirubin. The abilities for analyzing whole intact, oxygenated erythrocytes are proven, demonstrating the potential for the diagnosis of red blood cell related diseases, such as different types of anemia and hemolytic disorders. The optical fiber enables an efficient light-guiding within a miniaturized sample volume of only a few micro-liters and provides a tremendously improved analytical sensitivity (LODs of 0...
October 17, 2016: Analyst
A Parmigiani, A V Budanov
Sestrins are a family of stress-responsive genes that have evolved to attenuate damage induced by stress caused to the cell. By virtue of their antioxidant activity, protein products of Sestrin genes prevent the accumulation of reactive oxygen species within the cell, thereby attenuating the detrimental effects of oxidative stress. In parallel, Sestrins participate in several signaling pathways that control the activity of the target of rapamycin protein kinase (TOR). TOR is a crucial sensor of intracellular and extracellular conditions that promotes cell growth and anabolism when nutrients and growth factors are abundant...
2016: International Review of Cell and Molecular Biology
Zsuzsanna Kolbert, Nóra Lehotai, Árpád Molnár, Gábor Feigl
Elevated levels of selenium (Se) cause toxicity in non-accumulator plant species. The primary reasons for toxic Se effect have been considered to be selenoprotein accumulation and oxidative stress. However, based on our recent paper in Plant Cell Reports and previous literature data we suggest that disturbances in the homeostasis of both reactive oxygen and nitrogen species result in selenium-induced nitro-oxidative stress, contributing to toxicity. The most characteristic symptom of Se exposure is the inhibited root elongation which is partly caused by hormonal disturbances...
October 3, 2016: Plant Signaling & Behavior
Peiguang Hu, Limei Chen, Xiongwu Kang, Shaowei Chen
Noble metal nanoparticles represent a unique class of functional nanomaterials with physical and chemical properties that deviate markedly from those of their atomic and bulk forms. In order to stabilize the nanoparticles and further manipulate the materials properties, surface functionalization with organic molecules has been utilized as a powerful tool. Among those, mercapto derivatives have been used extensively as the ligands of choice for nanoparticle surface functionalization by taking advantage of the strong affinity of thiol moieties to transition metal surfaces forming (polar) metal-thiolate linkages...
October 3, 2016: Accounts of Chemical Research
Zdeněk Petrášek, Juan M Bolivar, Bernd Nidetzky
The dependence of the luminescence lifetime on the probe environment is the basis of a range of sensing techniques. The major advantage of using the lifetime as the sensitive parameter is its independence on the probe concentration. However, the instrumentation for lifetime measurements is complex, generally requiring time-resolved excitation and detection. Here, we present a simple method for the measurement of luminescence lifetimes on the microsecond scale based on variable excitation time determined by the scanning velocity...
October 12, 2016: Analytical Chemistry
Xiang Xiao, Wen-Wen Zhu, Qiu-Yue Liu, Hang Yuan, Wen-Wei Li, Li-Jun Wu, Qian Li, Han-Qing Yu
The release of nanomaterials into the environment, due to their massive production and application today, has caused ecological and health safety concerns. Semiconductor photocatalysts like TiO2 exhibit cytotoxicity to bacterial cells when exposed to UV irradiation. However, information about their impacts on individual or group bacterial behaviors is limited. In this work, the biofilm formation of Escherichia coli K12 in the presence of TiO2 with and without UV irradiation was investigated and biofilm formation was found not to be affected under the sole application of TiO2 or UV irradiation...
October 13, 2016: Environmental Science & Technology
Damien Maura, Ronen Hazan, Tomoe Kitao, Alicia E Ballok, Laurence G Rahme
Pseudomonas aeruginosa defies eradication by antibiotics and is responsible for acute and chronic human infections due to a wide variety of virulence factors. Currently, it is believed that MvfR (PqsR) controls the expression of many of these factors indirectly via the pqs and phnAB operons. Here we provide strong evidence that MvfR may also bind and directly regulate the expression of additional 35 loci across the P. aeruginosa genome, including major regulators and virulence factors, such as the quorum sensing (QS) regulators lasR and rhlR, and genes involved in protein secretion, translation, and response to oxidative stress...
September 28, 2016: Scientific Reports
Xin-Chun Huang, Yuko Inoue-Aono, Yuji Moriyasu, Pei-Ying Hsieh, Wei-Ming Tu, Shae-Chien Hsiao, Wan-Neng Jane, Hsin-Yun Hsu
Autophagy is a self-protection process against reactive oxygen species (ROS). The intracellular level of ROS increased when cells were cultured under nutrient starvation. Antioxidants such as glutathione and ascorbic acid play an important role in ROS removal. However, the cellular redox state in the autophagic pathway is still unclear. Herein, we developed a new redox-sensitive probe with a disulfide-linked silica scaffold to enable the sensing of the reduction environment in cell organelles. This redox-responsive silica nanoprobe (ReSiN) could penetrate the plant cell wall and release fluorescent molecules in response to redox states...
October 6, 2016: Analytical Chemistry
Chang Lu, Po-Jung Jimmy Huang, Biwu Liu, Yibin Ying, Juewen Liu
Fluorescently labeled DNA adsorbed on graphene oxide (GO) is a well-established sensing platform for detecting a diverse range of analytes. GO is a loosely defined material and its oxygen content may vary depending on the condition of preparation. Sometimes, a further reduction step is intentionally performed to decrease the oxygen content, and the resulting material is called reduced GO (rGO). In this study, DNA adsorption and desorption from GO and rGO is systematically compared. Under the same salt concentration, DNA adsorbs slightly faster with a 2...
October 6, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Atsushi Matsuzawa
Reactive oxygen species (ROS) are not only cytotoxic products from external and internal environment, but also important mediators of redox signaling. Therefore, thioredoxin (Trx) as an antioxidant maintains the balance of the thiol-related redox status, and also plays pivotal roles in the regulation of redox signaling. Trx senses and responds to environmental oxidative stress and ROS generated by cellular respiration, metabolism, and immune response, and then modulates the redox status, function, and activity of its target signaling proteins...
September 22, 2016: Archives of Biochemistry and Biophysics
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