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ChemistryOpen Jun 2022The increasing application of positron emission tomography (PET) in nuclear medicine has stimulated the extensive development of a multitude of novel and versatile... (Review)
Review
The increasing application of positron emission tomography (PET) in nuclear medicine has stimulated the extensive development of a multitude of novel and versatile techniques to introduce fluorine-18, especially for the radiolabelling of biologically or pharmacologically active molecules. Taking into consideration that the introduction of fluorine-18 (t =109.8 min) mostly proceeds under harsh conditions, radiolabelling of such molecules represents a challenge and is of enormous interest. Ideally, it should proceed in a regioselective manner under mild physiological conditions, in an acceptable time span, with high yields and high specific activities. Special attention has been drawn to 2-fluoroethyl and 3-fluoropropyl groups, which are often the active sites of radiofluorinated compounds. Precursors containing an ammonium leaving group - such as a strained azetidinium or aziridinium moiety - can help to overcome these obstacles leading to a convenient and mild introduction of [ F]fluoride with high radiochemical yields.
Topics: Ammonium Compounds; Positron-Emission Tomography; Radiochemistry; Radiopharmaceuticals; Tomography, X-Ray Computed
PubMed: 35736542
DOI: 10.1002/open.202200039 -
Nature Communications Feb 2022The impacts of enhanced nitrogen (N) deposition on the global forest carbon (C) sink and other ecosystem services may depend on whether N is deposited in reduced...
The impacts of enhanced nitrogen (N) deposition on the global forest carbon (C) sink and other ecosystem services may depend on whether N is deposited in reduced (mainly as ammonium) or oxidized forms (mainly as nitrate) and the subsequent fate of each. However, the fates of the two key reactive N forms and their contributions to forest C sinks are unclear. Here, we analyze results from 13 ecosystem-scale paired N-labelling experiments in temperate, subtropical, and tropical forests. Results show that total ecosystem N retention is similar for ammonium and nitrate, but plants take up more labelled nitrate ([Formula: see text]%) ([Formula: see text]) than ammonium ([Formula: see text]%) while soils retain more ammonium ([Formula: see text]%) than nitrate ([Formula: see text]%). We estimate that the N deposition-induced C sink in forests in the 2010s is [Formula: see text] Pg C yr, higher than previous estimates because of a larger role for oxidized N and greater rates of global N deposition.
Topics: Ammonium Compounds; Carbon Sequestration; Environment; Environmental Restoration and Remediation; Forests; Nitrates; Nitrogen Isotopes; Nitrogen Oxides; Soil; Trees
PubMed: 35169118
DOI: 10.1038/s41467-022-28345-1 -
Journal of Experimental Botany Jul 2020The enzymatic controlled metabolic processes in cells occur at their optimized pH ranges, therefore cellular pH homeostasis is fundamental for life. In plants, the... (Review)
Review
The enzymatic controlled metabolic processes in cells occur at their optimized pH ranges, therefore cellular pH homeostasis is fundamental for life. In plants, the nitrogen (N) source for uptake and assimilation, mainly in the forms of nitrate (NO3-) and ammonium (NH4+) quantitatively dominates the anion and cation equilibrium and the pH balance in cells. Here we review ionic and pH homeostasis in plant cells and regulation by N source from the rhizosphere to extra- and intracellular pH regulation for short- and long-distance N distribution and during N assimilation. In the process of N transport across membranes for uptake and compartmentation, both proton pumps and proton-coupled N transporters are essential, and their proton-binding sites may sense changes of apoplastic or intracellular pH. In addition, during N assimilation, carbon skeletons are required to synthesize amino acids, thus the combination of NO3- or NH4+ transport and assimilation results in different net charge and numbers of protons in plant cells. Efficient maintenance of N-controlled cellular pH homeostasis may improve N uptake and use efficiency, as well as enhance the resistance to abiotic stresses.
Topics: Ammonium Compounds; Homeostasis; Hydrogen-Ion Concentration; Nitrates; Nitrogen; Plant Physiological Phenomena
PubMed: 32206788
DOI: 10.1093/jxb/eraa150 -
International Journal of Molecular... Aug 2021Nitrogen is an important factor limiting the growth and yield of rice. However, the excessive application of nitrogen will lead to water eutrophication and economic... (Review)
Review
Nitrogen is an important factor limiting the growth and yield of rice. However, the excessive application of nitrogen will lead to water eutrophication and economic costs. To create rice varieties with high nitrogen use efficiency (NUE) has always been an arduous task in rice breeding. The processes for improving NUE include nitrogen uptake, nitrogen transport from root to shoot, nitrogen assimilation, and nitrogen redistribution, with each step being indispensable to the improvement of NUE. Here, we summarize the effects of absorption, transport, and metabolism of nitrate, ammonium, and amino acids on NUE, as well as the role of hormones in improving rice NUE. Our discussion provide insight for further research in the future.
Topics: Amino Acids; Ammonium Compounds; Gene Regulatory Networks; Genetic Variation; Nitrates; Nitrogen; Oryza; Plant Growth Regulators
PubMed: 34445746
DOI: 10.3390/ijms22169040 -
Molecules (Basel, Switzerland) May 2020Nosocomial infections, which greatly increase morbidity among hospitalized patients, together with growing antibiotic resistance still encourage many researchers to...
Nosocomial infections, which greatly increase morbidity among hospitalized patients, together with growing antibiotic resistance still encourage many researchers to search for novel antimicrobial compounds. Picolinium salts with different lengths of alkyl chains (C, C, C) were prepared by Menshutkin-like reaction and evaluated with respect to their biological activity, i.e., lipophilicity and critical micellar concentration. Picolinium salts with C and C side chains achieved similar or even better results when in terms of antimicrobial efficacy than benzalkoniums; notably, their fungicidal efficiency was substantially more potent. The position of the methyl substituent on the aromatic ring does not seem to affect antimicrobial activity, in contrast to the effect of length of the -alkyl chain. Concurrently, picolinium salts exhibited satisfactory low cytotoxicity against mammalian cells, i.e., lower than that of benzalkonium compounds, which are considered as safe.
Topics: Animals; Anti-Bacterial Agents; Anti-Infective Agents; Antiviral Agents; CHO Cells; Candida; Cell Survival; Cricetulus; Fungi; Gram-Negative Bacteria; Gram-Positive Bacteria; Herpesvirus 3, Human; Microbial Sensitivity Tests; Picolinic Acids; Quaternary Ammonium Compounds; Structure-Activity Relationship; Surface-Active Agents
PubMed: 32403238
DOI: 10.3390/molecules25092254 -
Antimicrobial Resistance and Infection... Apr 2023Due to the substantial increase in the use of disinfectants containing quaternary ammonion compounds (QACs) in healthcare and community settings during the COVID-19... (Review)
Review
BACKGROUND
Due to the substantial increase in the use of disinfectants containing quaternary ammonion compounds (QACs) in healthcare and community settings during the COVID-19 pandemic, there is increased concern that heavy use might cause bacteria to develop resistance to QACs or contribute to antibiotic resistance. The purpose of this review is to briefly discuss the mechanisms of QAC tolerance and resistance, laboratory-based evidence of tolerance and resistance, their occurrence in healthcare and other real-world settings, and the possible impact of QAC use on antibiotic resistance.
METHODS
A literature search was conducted using the PubMed database. The search was limited to English language articles dealing with tolerance or resistance to QACs present in disinfectants or antiseptics, and potential impact on antibiotic resistance. The review covered the period from 2000 to mid-Jan 2023.
RESULTS
Mechanisms of QAC tolerance or resistance include innate bacterial cell wall structure, changes in cell membrane structure and function, efflux pumps, biofilm formation, and QAC degradation. In vitro studies have helped elucidate how bacteria can develop tolerance or resistance to QACs and antibiotics. While relatively uncommon, multiple episodes of contaminated in-use disinfectants and antiseptics, which are often due to inappropriate use of products, have caused outbreaks of healthcare-associated infections. Several studies have identified a correlation between benzalkonium chloride (BAC) tolerance and clinically-defined antibiotic resistance. The occurrence of mobile genetic determinants carrying multiple genes that encode for QAC or antibiotic tolerance raises the concern that widespread QAC use might facilitate the emergence of antibiotic resistance. Despite some evidence from laboratory-based studies, there is insufficient evidence in real-world settings to conclude that frequent use of QAC disinfectants and antiseptics has promoted widespread emergence of antibiotic resistance.
CONCLUSIONS
Laboratory studies have identified multiple mechanisms by which bacteria can develop tolerance or resistance to QACs and antibiotics. De novo development of tolerance or resistance in real-world settings is uncommon. Increased attention to proper use of disinfectants is needed to prevent contamination of QAC disinfectants. Additional research is needed to answer many questions and concerns related to use of QAC disinfectants and their potential impact on antibiotic resistance.
Topics: Humans; Disinfectants; Anti-Infective Agents, Local; Ammonium Compounds; Quaternary Ammonium Compounds; Pandemics; COVID-19; Drug Resistance, Microbial; Bacteria; Anti-Bacterial Agents
PubMed: 37055844
DOI: 10.1186/s13756-023-01241-z -
Plant & Cell Physiology Sep 2021Nitrogen is the most important macroelement required for the composition of key molecules, such as nucleic acids, proteins and other organic compounds. As sessile... (Review)
Review
Nitrogen is the most important macroelement required for the composition of key molecules, such as nucleic acids, proteins and other organic compounds. As sessile organisms, plants have evolved sophisticated mechanisms to acquire nitrogen for their normal growth and development. Besides the transcriptional and translational regulation of nitrogen uptake, assimilation, remobilization and signal transduction, posttranslational modifications (PTMs) are shown to participate in these processes in plants. In addition to alterations in protein abundance, PTMs may dramatically increase the complexity of the proteome without the concomitant changes in gene transcription and have emerged as an important type of protein regulation in terms of protein function, subcellular localization and protein activity and stability. Herein, we briefly summarize recent advances on the posttranslational regulation of nitrogen uptake, assimilation, remobilization and nitrogen signaling and discuss the underlying mechanisms of PTMs as well as the signal output of such PTMs. Understanding these regulation mechanisms will provide novel insights for improving the nitrogen use efficiency of plants.
Topics: Ammonium Compounds; Anion Transport Proteins; Nitrate Transporters; Nitrogen; Phosphorylation; Plant Proteins; Plants; Protein Processing, Post-Translational; Signal Transduction; Ubiquitination
PubMed: 33493288
DOI: 10.1093/pcp/pcab008 -
Physiologia Plantarum Nov 2021The simultaneous presence of different N-forms in the rhizosphere leads to beneficial effects on nitrogen (N) nutrition in plants. Although widely used as fertilizers,...
The simultaneous presence of different N-forms in the rhizosphere leads to beneficial effects on nitrogen (N) nutrition in plants. Although widely used as fertilizers, the occurrence of cross connection between urea and ammonium nutrition has been scarcely studied in plants. Maize fed with a mixture of urea and ammonium displayed a better N-uptake efficiency than ammonium- or urea-fed plants (Buoso et al., Plant Physiol Biochem, 2021a; 162: 613-623). Through multiomic approaches, we provide the molecular characterization of maize response to urea and ammonium nutrition. Several transporters and enzymes involved in N-nutrition were upregulated by all three N-treatments (urea, ammonium, or urea and ammonium). Already after 1 day of treatment, the availability of different N-forms induced specific transcriptomic and metabolomic responses. The combination of urea and ammonium induced a prompt assimilation of N, characterized by high levels of some amino acids in shoots. Moreover, ZmAMT1.1a, ZmGLN1;2, ZmGLN1;5, ZmGOT1, and ZmGOT3, as well transcripts involved in glycolysis-TCA cycle were induced in roots by urea and ammonium mixture. Depending on N-form, even changes in the composition of phytohormones were observed in maize. This study paves the way to formulate guidelines for the optimization of N fertilization to improve N-use efficiency in maize and therefore limit N-losses in the environment.
Topics: Ammonium Compounds; Fertilizers; Gene Expression Regulation, Plant; Nitrogen; Plant Roots; Transcriptome; Urea; Zea mays
PubMed: 34245168
DOI: 10.1111/ppl.13493 -
Ecotoxicology and Environmental Safety Dec 2020Disinfectant quaternary ammonium compounds (Quats) have diverse uses in a variety of consumer and commercial products, particularly cleaning products. With the emergence... (Review)
Review
Disinfectant quaternary ammonium compounds (Quats) have diverse uses in a variety of consumer and commercial products, particularly cleaning products. With the emergence of the COVID-19 pandemic, they have become a primary tool to inactivate the SARS-CoV-2 virus on surfaces. Disinfectant Quats have very low vapor pressure, and following the use phase of the products in which they are found, disposal is typically "down-the-drain" to wastewater treatment systems. Consequently, the potential for the greatest environmental effect is to the aquatic environment, from treated effluent, and potentially to soils, which might be amended with wastewater biosolids. Among the earliest used and still common disinfectant Quats are the alkyl dimethyl benzyl ammonium chloride (ADBAC) compounds and the dialkyl dimethyl ammonium chloride (DDAC) compounds. They are cationic surfactants often found in consumer and commercial surface cleaners. Because of their biocidal properties, disinfectant Quats are heavily regulated for human and environmental safety around the world. Consequently, there is a robust database of information regarding the ecological hazards and environmental fate of ADBAC and DDAC; however, some of the data presented are from unpublished studies that have been submitted to and reviewed by regulatory agencies (i.e., EPA and European Chemicals Agency) to support antimicrobial product registration. We summarize the available environmental fate data and the acute and chronic aquatic ecotoxicity data for freshwater species, including algae, invertebrates, fish, and plants using peer-reviewed literature and unpublished data submitted to and summarized by regulatory agencies. The lower limit of the range of the ecotoxicity data for disinfectant Quats tends to be lower than that for other surface active agents, such as nonionic or anionic surfactants. However, ecotoxicity is mitigated by environmental fate characteristics, the data for which we also summarize, including high biodegradability and a strong tendency to sorb to wastewater biosolids, sediment, and soil. As a result, disinfectant Quats are largely removed during wastewater treatment, and those residues discharged in treated effluent are likely to rapidly bind to suspended solids or sediments, thus mitigating their toxicity.
Topics: Animals; Aquatic Organisms; Biodegradation, Environmental; COVID-19; Disinfectants; Ecotoxicology; Humans; Pandemics; Quaternary Ammonium Compounds; Risk Assessment; SARS-CoV-2; Wastewater; Water Pollutants, Chemical; Water Purification
PubMed: 32890921
DOI: 10.1016/j.ecoenv.2020.111116 -
Current Biology : CB Jun 2022Plants need at least 13 different nutrients to maintain optimal growth. Nitrogen and phosphorus, from the Greek 'phôs' (meaning 'light') and 'phoros' (meaning...
Plants need at least 13 different nutrients to maintain optimal growth. Nitrogen and phosphorus, from the Greek 'phôs' (meaning 'light') and 'phoros' (meaning 'bearer'), are the main nutrients limiting plant growth in both agricultural and natural ecosystems. Agriculture has relied heavily since the mid 1950s on the use of synthetic ammonium- and phosphorus-based fertilizers to increase crop productivity. While industrial synthesis of ammonium relies on the chemical conversion of atmospheric nitrogen, phosphorus is mined from finite reserves concentrated in a few countries. Considering our current dependence on phosphorus fertilizers for food production and the geopolitical aspects associated with current resources, it will be important to develop technologies enabling the maintenance of high crop yield with reduced fertilizer input. This will require an in-depth knowledge on the various pathways that enable plants to acquire phosphorus from the soil and maximize its economical use for growth and reproduction. In this primer, we give an overview of the factors limiting phosphorus acquisition by plants and highlight various pathways and strategies plants have evolved at the level of development, metabolism and signal transduction to adapt to phosphorus deficiency.
Topics: Agriculture; Ammonium Compounds; Ecosystem; Fertilizers; Nitrogen; Phosphates; Phosphorus; Plants; Soil
PubMed: 35728542
DOI: 10.1016/j.cub.2022.03.073