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Yang Wang, Jianwei Lu, Tao Ren, Saddam Hussain, Chen Guo, Sen Wang, Rihuan Cong, Xiaokun Li
The increasing food demands from an expanding population necessitate global efforts to increase crop production and ensure food security. The rate of nitrogen (N) fertilizer application is strongly related to crop yield. However, although the application of N fertilizer significantly increases the number of tillers in rice, late emerging tillers usually produce lower yields compared with early emerging tillers. Understanding the physiological constraints of late emerging rice tillers is critical for further increasing rice grain yields...
March 2017: AoB Plants
Jorge Royes, Víctor Polo, Santiago Uriel, Luis Oriol, Milagros Piñol, Rosa M Tejedor
Chiral photoinduction in a photoresponsive gel based on an achiral 2D architecture with high geometric anisotropy and low roughness has been investigated. Circularly polarized light (CPL) was used as a chiral source and an azobenzene chromophore was employed as a chiral trigger. The chiral photoinduction was studied by evaluating the preferential excitation of enantiomeric conformers of the azobenzene units. Crystallographic data and density functional theory (DFT) calculations show how chirality is transferred to the achiral azomaterials as a result of the combination of chiral photochemistry and supramolecular interactions...
May 19, 2017: Physical Chemistry Chemical Physics: PCCP
Lukasz Kowalik, James K Chen
Developmental biology has been continually shaped by technological advances, evolving from a descriptive science into one immersed in molecular and cellular mechanisms. Most recently, genome sequencing and 'omics' profiling have provided developmental biologists with a wealth of genetic and biochemical information; however, fully translating this knowledge into functional understanding will require new experimental capabilities. Photoactivatable probes have emerged as particularly valuable tools for investigating developmental mechanisms, as they can enable rapid, specific manipulations of DNA, RNA, proteins, and cells with spatiotemporal precision...
May 17, 2017: Nature Chemical Biology
Rebecca J Rapf, Russell J Perkins, Barry K Carpenter, Veronica Vaida
The aqueous phase photochemistry of pyruvic acid, an important oxidation product of isoprene, is known to generate larger oligomeric species that may contribute to the formation of secondary organic aerosol in the atmosphere. Using high resolution negative mode electrospray ionization mass spectrometry, the aqueous photochemistry of dilute solutions of pyruvic acid (10, 1, and 0.5 mM) under anaerobic conditions was investigated. Even at the lowest concentration, covalently-bonded dimers and trimers of pyruvic acid were observed as photochemical products...
May 16, 2017: Journal of Physical Chemistry. A
Christian Brackmann, Bo Zhou, Per Samuelsson, Vladimir A Alekseev, Alexander A Konnov, Zhongshan Li, Marcus Aldén
A new scheme for NH2 detection by means of laser-induced fluorescence (LIF) with excitation around wavelength 385nm, accessible using the second harmonic of a solid-state Alexandrite laser, is presented. Detection of NH2 was confirmed by identification of corresponding lines in fluorescence excitation spectra measured in premixed NH3-air flames and on NH2 radicals generated through NH3 photolysis in a nonreactive flow at ambient conditions. Moreover, spectral simulations allow for tentative NH2 line identification...
May 4, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Keiji Fushimi, Masahiko Ikeuchi, Rei Narikawa
This article highlights the paper by Rockwell et al. in the current issue of Photochemistry and Photobiology. Rockwell et al. describe the discovery of novel two-Cys photocycles within the "expanded red/green" (XRG) cyanobacteriochrome (CBCR) lineage. Comprehensive phylogenetic analysis revealed that several XRG CBCRs possess a second Cys residue in the DXCF (Asp-Xaa-Cys-Phe) motif conserved among the DXCF CBCR lineage. Spectral studies identified that these CBCRs showed green/blue or ultraviolet/blue reversible photoconversion abilities...
May 2017: Photochemistry and Photobiology
Margarita V Rodionova, Sergei K Zharmukhamedov, Mehmet Sayım Karacan, Kubra Begum Venedik, Alexandr V Shitov, Turgay Tunç, Serhat Mamaş, Vladimir D Kreslavski, Nurcan Karacan, Vyacheslav V Klimov, Suleyman I Allakhverdiev
Increasing inefficiency of production of important agricultural plants raises one of the biggest problems in the modern world. Herbicide application is still the best method of weed management. Traditional herbicides blocking only one of the plant metabolic pathways is ineffective due to the rapid growth of herbicide-resistant weeds. The synthesis of novel compounds effectively suppressing several metabolic processes, and therefore achieving the synergism effect would serve as the alternative approach to weed problem...
May 11, 2017: Photosynthesis Research
Chizhu Ding, Zibiao Li
The most common methods used for drug administrations are pills, injections, lotions and suppositories. The preferred means is oral dosage forms as it is simple, painless and self-administered. However, the drugs are usually degraded within gastrointestinal tract or not absorbed in sufficient quality to be effective. Over the years, a variety of other administration means have evolved to show specific advantages for particular agents and certain diseases. In this review, various nano-delivery systems consisting of different covalent linkages to conjugate the therapeutic molecules as well as those that carry the unmodified drug molecules by encapsulating or complexation are summarized, including ester, amide/peptide, disulfide, hydrazone, hypoxia-activated and self-immolative linkages...
July 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Rebecca J Rapf, Russell J Perkins, Haishen Yang, Garret M Miyake, Barry K Carpenter, Veronica Vaida
The aqueous phase photochemistry of a series of amphiphilic α-keto acids with differing linear alkyl chain lengths was investigated, demonstrating the ability of sunlight-initiated reactions to build molecular complexity under environmentally relevant conditions. We show that the photochemical reaction mechanisms for α-keto acids in aqueous solution are robust and generalizable across alkyl chain lengths. The organic radicals generated during photolysis are indiscriminate, leading to a large mixture of photoproducts that are observed using high-resolution electrospray ionization mass spectrometry, but these products are identifiable following literature photochemical mechanisms...
May 16, 2017: Journal of the American Chemical Society
Si Wu, Hans-Jürgen Butt
Near-infrared (NIR) light is better suited than ultraviolet (UV) light for biomedical applications because it penetrates deeper into tissue and causes less photodamage to biological systems. The use of NIR light to control biointerfaces has attracted increasing interest. Here, we review NIR photoreactions at interfaces based on upconverting nanoparticles (UCNPs). UCNPs can convert NIR light to UV or visible light, which can then induce photoreactions of photosensitive compounds. This process is referred to as UCNP-assisted photochemistry...
May 8, 2017: Physical Chemistry Chemical Physics: PCCP
K Chekanov, E Schastnaya, A Solovchenko, E Lobakova
The atmospheric CO2 level is limiting for growth of phototrophic organisms such as microalgae, so CO2 enrichment boosts the growth and photosynthesis of microalgal cultures. Still, excessive CO2 injection might inhibit photosynthesis of microalgae. We investigated the effect of continuous sparging of the cultures of Haematococcus pluvialis BM 1 (IPPAS H-2018) (Chlorophyceae), the richest natural source of the value-added pigment astaxanthin. H. pluvialis cultures with CO2-enriched air-gas mixtures (with CO2 level from the atmospheric to 20%) on growth and astaxanthin accumulation in the microalga...
April 27, 2017: Journal of Photochemistry and Photobiology. B, Biology
Jayakumar Bose, Rana Munns, Sergey Shabala, Matthew Gilliham, Barry Pogson, Stephen D Tyerman
Salt stress impacts multiple aspects of plant metabolism and physiology. For instance it inhibits photosynthesis through stomatal limitation, causes excessive accumulation of sodium and chloride in chloroplasts, and disturbs chloroplast potassium homeostasis. Most research on salt stress has focused primarily on cytosolic ion homeostasis with few studies of how salt stress affects chloroplast ion homeostasis. This review asks the question whether membrane-transport processes and ionic relations are differentially regulated between glycophyte and halophyte chloroplasts and whether this contributes to the superior salt tolerance of halophytes...
May 2, 2017: Journal of Experimental Botany
Boris Wezisla, Jörg Lindner, Ujjal Das, Alexander C Filippou, Peter Vöhringer
The eminent role of metallacyclobutadienes as catalytic intermediates in organic synthesis and polymer chemistry is widely acknowledged. In contrast, their photochemistry is as yet entirely unexplored. Herein, the photo-induced primary processes of a ferracyclobutadiene tricarbonyl complex in solution are revealed by femtosecond mid-infrared spectroscopy. The time-resolved vibrational spectra expose an ultrafast substitution of a basal CO ligand by a solvent molecule in a consecutive dissociation-association mechanism...
May 4, 2017: Angewandte Chemie
Emma E Blackham, Kevin I Booker-Milburn
A short, 5-step total synthesis of (±)-3-demethoxyerythratidinone from a simple pyrrole derivative is described. Features include the formation of gram quantities of a key tricylic aziridine from a challenging photochemical cascade reaction through the use of flow photochemistry. The final step involved a highly unusual Heck cyclization whereby ligand control enabled efficient formation of the natural product in 69 % yield from the minor isomer present in an equilibrating mixture of labile enamines.
June 1, 2017: Angewandte Chemie
Sofia Kajouj, Lionel Marcélis, Vincent Lemaur, David Beljonne, Cécile Moucheron
Polyazaaromatic ruthenium(ii) complexes have been largely studied over the last decades, particularly in the scope of the biological applications, for the development of new diagnostic and phototherapeutic agents. In this context, Ru(ii) complexes able to react with biomolecules upon excitation are of great interest. Photo-oxidizing Ru(ii) complexes based on π-deficient ligands, such as bpz (2,2'-bypyrazine) and TAP (1,4,5,8-tetraazaphenathrene), were designed to allow a photo-induced electron transfer (PET) to take place in presence of biomolecules, thanks to their highly photo-oxidizing (3)MLCT state...
May 4, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Alex R Jones
Biologically active derivatives of vitamin B12 are organometallic cobalt-corrinoid complexes crucial for the healthy function of humans, animals and microbes. Their role as cofactors to numerous, thermally-driven metabolic enzymes is well described, and varies depending on the nature of the upper axial ligand. This ligand also significantly influences the photophysics and photochemistry of B12. In this Perspective I will discuss the various aspects of B12 photochemistry, from its dynamic spin chemistry to the considerable potential it has for biotechnology applications...
May 2, 2017: Photochemical & Photobiological Sciences
Emilie M F Billaud, Elnaz Shahbazali, Muneer Ahamed, Frederik Cleeren, Timothy Noël, Michel Koole, Alfons Verbruggen, Volker Hessel, Guy Bormans
Pretargeted PET imaging has emerged as an effective two-step in vivo approach that combines the superior affinity and selectivity of antibodies with the rapid pharmacokinetics and favorable dosimetry of smaller molecules radiolabeled with short-lived radionuclides. This approach can be based on the bioorthogonal inverse-electron-demand Diels-Alder (IEDDA) reaction between tetrazines and trans-cyclooctene (TCO) derivatives. We aimed to develop new [(18)F]TCO-dienophiles with high reactivity for IEDDA reactions, and favorable in vivo stability and pharmacokinetics...
February 1, 2017: Chemical Science
Andrew M Hartley, Harley L Worthy, Samuel C Reddington, Pierre J Rizkallah, D Dafydd Jones
Through the genetic incorporation of a single phenyl azide group into superfolder GFP (sfGFP) at residue 148 we provide a molecular description of how this highly versatile chemical handle can be used to positively switch protein function in vitro and in vivo via either photochemistry or bioconjugation. Replacement of H148 with p-azido-l-phenylalanine (azF) blue shifts the major excitation peak ∼90 nm by disrupting the H-bond and proton transfer network that defines the chromophore charged state. Bioorthogonal click modification with a simple dibenzylcyclooctyne or UV irradiation shifts the neutral-anionic chromophore equilibrium, switching fluorescence to the optimal ∼490 nm excitation...
October 1, 2016: Chemical Science
Qifan Liu, Zhuang Wu, Jian Xu, Yan Lu, Hongmin Li, Xiaoqing Zeng
Methylsulfoxide radicals CH3SOx (x = 1-4) are key reactive sulfur species (RSS) in the atmospheric oxidation of volatile organic sulfur compounds (VOSCs). Through flash vacuum pyrolysis (FVP) of trifluoromethanesulfinic acid methyl ester CF3S(O)OCH3 at 1000 K, the methoxysulfinyl radical CH3OSO has been generated in the gas phase and subsequently characterized in cryogenic N2, Ar, and Ne matrices by IR spectroscopy. Upon 266 nm laser irradiation, CH3OSO efficiently isomerizes to the less stable methylsulfonyl radical CH3SO2 in matrices without noticeable decomposition...
May 4, 2017: Journal of Physical Chemistry. A
Victoria S Meadows
Oxygenic photosynthesis is Earth's dominant metabolism, having evolved to harvest the largest expected energy source at the surface of most terrestrial habitable zone planets. Using CO2 and H2O-molecules that are expected to be abundant and widespread on habitable terrestrial planets-oxygenic photosynthesis is plausible as a significant planetary process with a global impact. Photosynthetic O2 has long been considered particularly robust as a sign of life on a habitable exoplanet, due to the lack of known "false positives"-geological or photochemical processes that could also produce large quantities of stable O2...
April 26, 2017: Astrobiology
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