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Food Chemistry Nov 2022In an attempt to investigate the carbonyl-trapping abilities of 5-alkylresorcinols, this study describes the role of these compounds in inhibiting the formation of the...
In an attempt to investigate the carbonyl-trapping abilities of 5-alkylresorcinols, this study describes the role of these compounds in inhibiting the formation of the 2,5-dialkylpyridines (5-ethyl-2-methylpyridine, 5-butyl-2-propylpyridine, and 5-hexyl-2-pentylpyridine) produced by 2-alkenals (crotonaldehyde, 2-hexenal, and 2-octenal) in the presence of ammonia. 5-Alkylresorcinols (as well as orcinol and olivetol) inhibited the formation of pyridines to an extend that depended on the 2-alkenal involved and the reaction conditions. This inhibition was consequence of the trapping of 2-alkenals by the phenolics. Thus, the major adducts produced between the C21:0 alkylresorcinol and crotonaldehyde were isolated and characterized by nuclear magnetic resonance (NMR) and mass spectrometry (MS). These results confirm that, in addition to their free radical scavenging abilities, 5-alkylresorcinols also trap reactive carbonyls. Because trapped carbonyls are involved in the formation of flavors and processing-induced antioxidants, 5-alkylresorcinols might be implied in some of the observed differences between whole and refined grain products.
Topics: Ammonia; Magnetic Resonance Spectroscopy; Mass Spectrometry; Phenols
PubMed: 35661596
DOI: 10.1016/j.foodchem.2022.133372 -
Applied and Environmental Microbiology Apr 2020Ammonia monooxygenase (AMO) is a key nitrogen-transforming enzyme belonging to the same copper-dependent membrane monooxygenase family (CuMMO) as the particulate methane...
Ammonia monooxygenase (AMO) is a key nitrogen-transforming enzyme belonging to the same copper-dependent membrane monooxygenase family (CuMMO) as the particulate methane monooxygenase (pMMO). The AMO from ammonia-oxidizing archaea (AOA) is very divergent from both the AMO of ammonia-oxidizing bacteria (AOB) and the pMMO from methanotrophs, and little is known about the structure or substrate range of the archaeal AMO. This study compares inhibition by C to C linear 1-alkynes of AMO from two phylogenetically distinct strains of AOA, " Nitrosocosmicus franklandus" C13 and " Nitrosotalea sinensis" Nd2, with AMO from and pMMO from (Bath). An increased sensitivity of the archaeal AMO to short-chain-length alkynes (≤C) appeared to be conserved across AOA lineages. Similarities in C to C alkyne inhibition profiles between AMO from AOA and pMMO from suggested that the archaeal AMO has a narrower substrate range than AMO. Inhibition of AMO from " Nitrosocosmicus franklandus" and by the aromatic alkyne phenylacetylene was also investigated. Kinetic data revealed that the mechanisms by which phenylacetylene inhibits " Nitrosocosmicus franklandus" and are different, indicating differences in the AMO active site between AOA and AOB. Phenylacetylene was found to be a specific and irreversible inhibitor of AMO from " Nitrosocosmicus franklandus," and it does not compete with NH for binding at the active site. Archaeal and bacterial ammonia oxidizers (AOA and AOB, respectively) initiate nitrification by oxidizing ammonia to hydroxylamine, a reaction catalyzed by ammonia monooxygenase (AMO). AMO enzyme is difficult to purify in its active form, and its structure and biochemistry remain largely unexplored. The bacterial AMO and the closely related particulate methane monooxygenase (pMMO) have a broad range of hydrocarbon cooxidation substrates. This study provides insights into the AMO of previously unstudied archaeal genera, by comparing the response of the archaeal AMO, a bacterial AMO, and pMMO to inhibition by linear 1-alkynes and the aromatic alkyne, phenylacetylene. Reduced sensitivity to inhibition by larger alkynes suggests that the archaeal AMO has a narrower hydrocarbon substrate range than the bacterial AMO, as previously reported for other genera of AOA. Phenylacetylene inhibited the archaeal and bacterial AMOs at different thresholds and by different mechanisms of inhibition, highlighting structural differences between the two forms of monooxygenase.
Topics: Alkynes; Ammonia; Archaea; Oxidoreductases
PubMed: 32086308
DOI: 10.1128/AEM.02388-19 -
Ecotoxicology and Environmental Safety Aug 2022Anthropogenic factors and climate change have serious effects on the aquatic ecosystem and aquaculture. Among water pollutants, ammonia has the greatest impact on...
Anthropogenic factors and climate change have serious effects on the aquatic ecosystem and aquaculture. Among water pollutants, ammonia has the greatest impact on aquaculture organisms such as penaeid shrimp because it makes them more susceptible to infections. In this study, we explored the effects of ammonia stress (0, 50, 100, and 150 mg/L) on the molecular structure and functions of the multifunctional respiratory protein hemocyanin (HMC) in Penaeus vannamei. While the mRNA expression of Penaeus vannamei hemocyanin (PvHMC) was up-regulated after ammonia stress, both plasma hemocyanin protein and oxyhemocyanin (OxyHMC) levels decreased. Moreover, ammonia stress changed the molecular structure of hemocyanin, modulated the expression of protein phosphatase 2 A (PP2A) and casein kinase 2α (CK2α) to regulate the phosphorylation modification of hemocyanin, and enhanced its degradation into fragments by trypsin. Under moderate ammonia stress conditions, hemocyanin also undergoes glycosylation to improve its in vitro antibacterial activity and binding with Gram-negative (Vibrio parahaemolyticus) and Gram-positive (Staphylococcus aureus) bacteria, albeit differently. The current findings indicate that P. vannamei hemocyanin undergoes adaptive molecular modifications under ammonia stress enabling the shrimp to survive and counteract the consequences of the stress.
Topics: Ammonia; Animals; Ecosystem; Hemocyanins; Penaeidae; Vibrio parahaemolyticus
PubMed: 36068754
DOI: 10.1016/j.ecoenv.2022.113827 -
International Journal of Molecular... Jul 2021Ammonia is a well-known example of a two-state system and must be described in quantum-mechanical terms. In this article, we will explain the tunneling phenomenon that... (Review)
Review
Ammonia is a well-known example of a two-state system and must be described in quantum-mechanical terms. In this article, we will explain the tunneling phenomenon that occurs in ammonia molecules from the perspective of trajectory-based quantum dynamics, rather than the usual quantum probability perspective. The tunneling of the nitrogen atom through the potential barrier in ammonia is not merely a probability problem; there are underlying reasons and mechanisms explaining why and how the tunneling in ammonia can happen. Under the framework of quantum Hamilton mechanics, the tunneling motion of the nitrogen atom in ammonia can be described deterministically in terms of the quantum trajectories of the nitrogen atom and the quantum forces applied. The vibrations of the nitrogen atom about its two equilibrium positions are analyzed in terms of its quantum trajectories, which are solved from the Hamilton equations of motion. The vibration periods are then computed by the quantum trajectories and compared with the experimental measurements.
Topics: Ammonia; Molecular Dynamics Simulation; Quantum Theory
PubMed: 34361046
DOI: 10.3390/ijms22158282 -
Ecotoxicology and Environmental Safety Sep 2022Ammonia is one of the most important toxic metabolites in the intestine of animals. It can cause intestinal damage and associated intestinal diseases through different...
Ammonia is one of the most important toxic metabolites in the intestine of animals. It can cause intestinal damage and associated intestinal diseases through different endogenous or exogenous stimuli. However, the definition of harmful ammonia concentration and the molecular mechanism of ammonia - induced intestinal epithelial injury remain unclear. In this study, we found that the viability of porcine IPEC-J2 intestinal epithelial cells significantly decreased with the increase of NHCl dose (20-80 mM). Ammonia (40 mM NHCl) increased the expression level of ammonia transporter RHCG and disrupted the intestinal barrier function of IPEC-J2 cells by reducing the expression levels of the tight junction molecules ZO-1 and Claudin-1. Ammonia caused elevated levels of ROS and apoptosis in IPEC-J2 cells. This was manifested by decreased activity of antioxidant enzymes SOD and GPx, decreased mitochondrial membrane potential, and increased cytoplasmic Ca concentration. In addition, the expression levels of apoptosis-related molecules Caspase-9, Caspase-3, Fas, Caspase-8, p53 and Bax were increased, the expression level of anti-apoptotic molecule Bcl-2 was decreased. Moreover, the antioxidant NAC (N-acetyl-L-cysteamine) effectively alleviated ammonia-induced cytotoxicity, reduced ROS level, Ca concentration, and the apoptosis of IPEC-J2 cells. The results suggest that ammonia-induced excess ROS triggered apoptosis through mitochondrial pathway, death receptor pathway and DNA damage. This study can provide reference and theoretical basis for the definition of harmful ammonia concentration in pig intestine and the effect and mechanism of ammonia on pig intestinal health.
Topics: Ammonia; Animals; Antioxidants; Apoptosis; Cell Line; Epithelial Cells; Intestines; Reactive Oxygen Species; Swine
PubMed: 36037632
DOI: 10.1016/j.ecoenv.2022.114006 -
Water Research Oct 2022A shift from the acetoclastic to the hydrogenotrophic pathway in methanogenesis under ammonia inhibition is a common observation in anaerobic digestion. However, there...
A shift from the acetoclastic to the hydrogenotrophic pathway in methanogenesis under ammonia inhibition is a common observation in anaerobic digestion. However, there are still considerable knowledge gaps concerning the differential ammonia tolerance of acetoclastic and hydrogenotrophic methanogens (AMs and HMs), their responses to different ammonia species (NH, NH), and their recoverability after ammonia inhibition. With the successful enrichment of mesophilic AMs and HMs cultures, this study aimed at addressing the above knowledge gaps through batch inhibition/recovery tests and kinetic modeling under varying total ammonia (TAN, 0.2-10 g N/L) and pH (7.0-8.5) conditions. The results showed that the tolerance level of HMs to free ammonia (FAN, IC=1345 mg N/L) and NH (IC=6050 mg N/L) was nearly 11 times and 3 times those of AMs (NH, IC=123 mg N/L; NH, IC=2133 mg N/L), respectively. Consistent with general belief, the AMs were more impacted by FAN. However, the HMs were more adversely affected by NH when the pH was ≤8.0. A low TAN (1.0-4.0 g N/L) could cause irreversible inhibition of the AMs due to significant cell death, whereas the activity of HMs could be fully or even over recovered from severe ammonia stress (FAN≤ 0.9 g N/L or TAN≤10 g N/L; pH ≤8.0). The different tolerance responses of AMs and HMs might be associated with the cell morphology, multiple energy-converting systems, and Gibbs free energy from substrate-level phosphorylation.
Topics: Ammonia; Anaerobiosis; Bioreactors; Euryarchaeota; Methane
PubMed: 36099760
DOI: 10.1016/j.watres.2022.119029 -
Journal of Environmental Sciences... Apr 2023Ammonia, a common toxic gas, is not only one of the main causes of haze, but also can enter respiratory tract and directly affect the health of humans and animals. Pig...
Ammonia, a common toxic gas, is not only one of the main causes of haze, but also can enter respiratory tract and directly affect the health of humans and animals. Pig was used as an animal model for exploring the molecular mechanism and dose effect of ammonia toxicity to lung. In this study, the apoptosis of type II alveolar epithelial cells was observed in high ammonia exposure group using transmission electron microscopy. Gene and protein expression analysis using transcriptome sequencing and western blot showed that low ammonia exposure induced T-cell-involved proinflammatory response, but high ammonia exposure repressed the expression of DNA repair-related genes and affected ion transport. Moreover, high ammonia exposure significantly increased 8-hydroxy-2-deoxyguanosine (8-OHdG) level, meaning DNA oxidative damage occurred. In addition, both low and high ammonia exposure caused oxidative stress in pig lungs. Integrated analysis of transcriptome and metabolome revealed that the up-regulation of LDHB and ND2 took part in high ammonia exposure-affected pyruvate metabolism and oxidative phosphorylation progress, respectively. Inclusion, oxidative stress mediated ammonia-induced proinflammatory response and apoptosis of porcine lungs. These findings may provide new insights for understanding the ammonia toxicity to workers in livestock farms and chemical fertilizer plants.
Topics: Humans; Swine; Animals; Ammonia; Oxidative Stress; Apoptosis; 8-Hydroxy-2'-Deoxyguanosine; Lung
PubMed: 36503793
DOI: 10.1016/j.jes.2022.05.005 -
Annual Review of Physiology 2007Acid-base homeostasis to a great extent relies on renal ammonia metabolism. In the past several years, seminal studies have generated important new insights into the... (Review)
Review
Acid-base homeostasis to a great extent relies on renal ammonia metabolism. In the past several years, seminal studies have generated important new insights into the mechanisms of renal ammonia transport. In particular, the theory that ammonia transport occurs almost exclusively through nonionic NH(3) diffusion and NH(4)(+) trapping has given way to a model postulating that a variety of proteins specifically transport NH(3) and NH(4)(+) and that this transport is critical for normal ammonia metabolism. Many of these proteins transport primarily H(+) or K(+) but also transport NH(4)(+). Nonerythroid Rh glycoproteins transport ammonia and may represent critical facilitators of ammonia transport in the kidney. This review discusses the underlying aspects of renal ammonia transport as well as specific proteins with important roles in renal ammonia transport.
Topics: Ammonia; Animals; Biological Transport, Active; Carrier Proteins; Humans; Kidney
PubMed: 17002591
DOI: 10.1146/annurev.physiol.69.040705.142215 -
Journal of Hazardous Materials Mar 2023Anthropogenic acidification of water is an on-going environmental disaster for freshwater fishes. Fishes rely on ammonia excretion to eliminate the excess acid and...
Anthropogenic acidification of water is an on-going environmental disaster for freshwater fishes. Fishes rely on ammonia excretion to eliminate the excess acid and mitigate the harmful effects; however, it remains largely unknown how ammoniagenesis occurs and is coordinated with ammonia excretion upon acidic stress. Medaka (Oryzias latipes) was used to examine the effects of acidic stress on ammonia production and excretion. We reveal an undiscovered ammonia-producing cell type that is rich in glutaminase (GLS) and located adjacent to the ammonia-excreting ionocytes, Na/H exchanger (NHE) cells, in the gills. The gills, comparing with other ammoniagenetic organs, is the quickest to respond to the acidic stress by triggering GLS-dependent ammonia production. The unique division of labor between GLS and NHE cells in the gills allows medaka to simultaneously upregulate GLS activity and ammonia excretion shortly after exposure to acidic environments. Pharmacological experiment with a GLS inhibitor abolished the activated ammonia excretion, further suggesting the essential role of the unique feature in the responses to acidic stress. Our study shades light on a novel physiological mechanism to timely and efficiently mitigate adverse effects of acidification, providing a new way to assess the impact of on-going environmental acidification on fish.
Topics: Animals; Oryzias; Ammonia; Sodium-Hydrogen Exchangers; Fresh Water; Gills
PubMed: 36502720
DOI: 10.1016/j.jhazmat.2022.130539 -
Proceedings of the National Academy of... Aug 2022Archaeal membrane lipids are widely used for paleotemperature reconstructions, yet these molecular fossils also bear rich information about ecology and evolution of...
Archaeal membrane lipids are widely used for paleotemperature reconstructions, yet these molecular fossils also bear rich information about ecology and evolution of marine ammonia-oxidizing archaea (AOA). Here we identified thermal and nonthermal behaviors of archaeal glycerol dialkyl glycerol tetraethers (GDGTs) by comparing the GDGT-based temperature index (TEX) to the ratio of GDGTs with two and three cyclopentane rings (GDGT-2/GDGT-3). Thermal-dependent biosynthesis should increase TEX and decrease GDGT-2/GDGT-3 when the ambient temperature increases. This presumed temperature-dependent (PTD) trend is observed in GDGTs derived from cultures of thermophilic and mesophilic AOA. The distribution of GDGTs in suspended particulate matter (SPM) and sediments collected from above the pycnocline-shallow water samples-also follows the PTD trend. These similar GDGT distributions between AOA cultures and shallow water environmental samples reflect shallow ecotypes of marine AOA. While there are currently no cultures of deep AOA clades, GDGTs derived from deep water SPM and marine sediment samples exhibit nonthermal behavior deviating from the PTD trend. The presence of deep AOA increases the GDGT-2/GDGT-3 ratio and distorts the temperature-controlled correlation between GDGT-2/GDGT-3 and TEX. We then used Gaussian mixture models to statistically characterize these diagnostic patterns of modern AOA ecology from paleo-GDGT records to infer the evolution of marine AOA from the Mid-Mesozoic to the present. Long-term GDGT-2/GDGT-3 trends suggest a suppression of today's deep water marine AOA during the Mesozoic-early Cenozoic greenhouse climates. Our analysis provides invaluable insights into the evolutionary timeline and the expansion of AOA niches associated with major oceanographic and climate changes.
Topics: Ammonia; Archaea; Diglycerides; Evolution, Molecular; Membrane Lipids; Oxidation-Reduction; Phylogeny; Water
PubMed: 35905325
DOI: 10.1073/pnas.2123193119