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Water Research Nov 2022The toxic effect of unionized ammonia (NH) on aquatic organisms is receiving increasing attention due to the excessive nitrogen discharge to various surface waters....
The toxic effect of unionized ammonia (NH) on aquatic organisms is receiving increasing attention due to the excessive nitrogen discharge to various surface waters. Researches have suggested the scale-dependence of NH toxicity, being lower in field than under lab conditions. Such scale-dependence of toxicity is a big challenge to water quality criteria setting as the results solely from lab tests might not apply to natural ecosystems. Therefore, it is necessary to explore the underlying mechanism to understand the difference of toxicity across various spatial scales. In this study, we used the widely distributed gastropod Bellamya aeruginosa as the test animal and performed two 192-h microcosm experiments. Each experiment included a control and an ammonia addition treatment: N0(LC) & N+(LC), N0(LC) & N+(LC) (96-h LC = 0.8 mg NHN/L, 96-h LC = 18.1 mg NHN/L). Besides water-only, three potential key components (food, sediment, and submersed macrophytes) were included in the various treatments to mimic different complexity levels of aquatic ecosystems (Water, Water + Food, Water + Sediment, Water + Sediment + Macrophytes). The results showed that: 1) food directly improved the survival and growth of gastropods under expected lethal concentration of ammonia (96-h concentration of NHN = LC of the 96-h acute test); 2) sediment and macrophyte quickly decreased the ammonia concentration, mainly by sediment adsorption and macrophyte uptake, to alleviate the ammonia stress to gastropods and permitted them to survive and grow under expected lethal concentration of ammonia (96-h concentration of NHN = LC∼LC of the 96-h acute test); 3) sediment and macrophyte also provided additional food for gastropods; 4) under extremely high ammonia stress (i.e., 96-h LC, food was left uneaten and macrophyte died, and gastropods could, therefore, not be released from ammonia stress. Our results demonstrate that under moderate ammonia stress, the introduction of extra ecosystem elements (food, sediment, and macrophytes) significantly improved the survival and growth of gastropods, mainly by enhancing their tolerance and by quickly decreasing the NH concentration and thus toxicity. However, these introduced elements had little effect at very high concentration of ammonia (i.e., 96-h LC). Our findings add to the understanding of the reasons behind the previous observed scale-dependent toxicity of NH on aquatic organisms and contribute to better decisions on the role of NH in relation to water quality management.
Topics: Animals; Ecosystem; Ammonia; Aquatic Organisms; Nitrogen; Water Pollutants, Chemical
PubMed: 36323203
DOI: 10.1016/j.watres.2022.119266 -
Ecotoxicology and Environmental Safety Oct 2022Ammonia pollutants were usually found in aquatic environments is due to urban sewage, industrial wastewater discharge, and agricultural runoff and concentrations as high...
Ammonia pollutants were usually found in aquatic environments is due to urban sewage, industrial wastewater discharge, and agricultural runoff and concentrations as high as 180 mg/L (NH) have been reported in rivers. High ammonia levels are known to impair multiple tissue and cell functions and cause fish death. Although ammonia is a potent neurotoxin, how sublethal concentrations of ammonia influence the central nervous system (CNS) and the complex behaviors of fish is still unclear. In the present study, we demonstrated that acute sublethal ammonia exposure can change social behavior of adult zebrafish. The exposure to 90 mg /L of (NH) for 4 h induced a strong fear response and lower shoaling cohesion; exposure to 180 mg /L of (NH) for 4 h reduced the aggressiveness, and social recognition, while the anxiety, social preference, learning, and short-term memory were not affected. Messenger RNA expressions of glutaminase and glutamate dehydrogenase in the brain were induced, suggesting that ammonia exposure altered glutamate neurotransmitters in the CNS. Our findings in zebrafish provided delicate information of ammonia neurotoxicity in complex higher-order social behaviors, which has not been revealed previously. In conclusion, sublethal and acute ammonia exposure can change specific behaviors of fish, which might lead to reductions in individual and population fitness levels.
Topics: Ammonia; Animals; Anxiety; Cognition; Glutamate Dehydrogenase; Glutamates; Glutaminase; Neurotoxins; RNA, Messenger; Sewage; Social Behavior; Wastewater; Water Pollutants, Chemical; Zebrafish
PubMed: 36108432
DOI: 10.1016/j.ecoenv.2022.114058 -
NPJ Systems Biology and Applications Dec 2022The kidney plays a critical role in excreting ammonia during metabolic acidosis and liver failure. The mechanisms behind this process have been poorly explored. The...
The kidney plays a critical role in excreting ammonia during metabolic acidosis and liver failure. The mechanisms behind this process have been poorly explored. The present study combines results of in vivo experiments of increased total ammoniagenesis with systems biology modeling, in which eight rats were fed an amino acid-rich diet (HD group) and eight a normal chow diet (AL group). We developed a method based on elementary mode analysis to study changes in amino acid flux occurring across the kidney in increased ammoniagenesis. Elementary modes represent minimal feasible metabolic paths in steady state. The model was used to predict amino acid fluxes in healthy and pre-hyperammonemic conditions, which were compared to experimental fluxes in rats. First, we found that total renal ammoniagenesis increased from 264 ± 68 to 612 ± 87 nmol (100 g body weight) min in the HD group (P = 0.021) and a concomitated upregulation of NKCC2 ammonia and other transporters in the kidney. In the kidney metabolic model, the best predictions were obtained with ammonia transport as an objective. Other objectives resulting in a fair correlation with the measured fluxes (correlation coefficient >0.5) were growth, protein uptake, urea excretion, and lysine and phenylalanine transport. These predictions were improved when specific gene expression data were considered in HD conditions, suggesting a role for the mitochondrial glycine pathway. Further studies are needed to determine if regulation through the mitochondrial glycine pathway and ammonia transporters can be modulated and how to use the kidney as a therapeutic target in hyperammonemia.
Topics: Rats; Animals; Ammonia; Kidney; Amino Acids; Acidosis; Glycine
PubMed: 36539425
DOI: 10.1038/s41540-022-00257-2 -
Chemical Reviews Jun 2020Nitrogen fixation, the six-electron/six-proton reduction of N, to give NH, is one of the most challenging and important chemical transformations. Notwithstanding the... (Review)
Review
Nitrogen fixation, the six-electron/six-proton reduction of N, to give NH, is one of the most challenging and important chemical transformations. Notwithstanding the barriers associated with this reaction, significant progress has been made in developing molecular complexes that reduce N into its bioavailable form, NH. This progress is driven by the dual aims of better understanding biological nitrogenases and improving upon industrial nitrogen fixation. In this review, we highlight both mechanistic understanding of nitrogen fixation that has been developed, as well as advances in yields, efficiencies, and rates that make molecular alternatives to nitrogen fixation increasingly appealing. We begin with a historical discussion of N functionalization chemistry that traverses a timeline of events leading up to the discovery of the first molecular catalyst system and follow with a comprehensive overview of d-block compounds that have been targeted as catalysts up to and including 2019. We end with a summary of lessons learned from this significant research effort and last offer a discussion of key remaining challenges in the field.
Topics: Ammonia; Carbon; Catalysis; Ferric Compounds; Hydrazines; Iron; Molybdenum; Nitrogen; Nitrogen Fixation
PubMed: 32352271
DOI: 10.1021/acs.chemrev.9b00638 -
American Journal of Physiology. Cell... Feb 2020Whether SLC4A11 transports ammonia and its potential mode of ammonia transport (, NH, or NH-2H transport have been proposed) are controversial. In the absence of...
Whether SLC4A11 transports ammonia and its potential mode of ammonia transport (, NH, or NH-2H transport have been proposed) are controversial. In the absence of ammonia, whether SLC4A11 mediates significant conductive H(OH) transport is also controversial. The present study was performed to determine the mechanism of human SLC4A11 ammonia transport and whether the transporter mediates conductive H(OH) transport in the absence of ammonia. We quantitated H flux by monitoring changes in intracellular pH (pH) and measured whole cell currents in patch-clamp studies of HEK293 cells expressing the transporter in the absence and presence of NHCl. Our results demonstrate that SLC4A11 mediated conductive H(OH) transport that was stimulated by raising the extracellular pH (pH). Ammonia-induced HEK293 whole cell currents were also stimulated by an increase in pH. In studies using increasing NHCl concentrations with equal extracellular and intracellular concentrations, the shift in the reversal potential () due to the addition of ammonia was compatible with NH-H transport competing with H(OH) rather than NH-nH ( ≥ 2) transport. The increase in equivalent H(OH) flux observed in the presence of a transcellular H gradient was also compatible with SLC4A11-mediated NH-H flux. The NH versus data fit a theoretical model suggesting that NH-H and H(OH) competitively interact with the transporter. Studies of mutant SLC4A11 constructs in the putative SLC4A11 ion coordination site showed that both H(OH) transport and ammonia-induced whole cell currents were blocked suggesting that the H(OH) and NH-H transport processes share common features involving the SLC4A11 transport mechanism.
Topics: Ammonia; Anion Transport Proteins; Antiporters; Bicarbonates; Cell Line; HEK293 Cells; Humans; Hydrogen-Ion Concentration; Ion Transport; Sodium
PubMed: 31774702
DOI: 10.1152/ajpcell.00425.2019 -
MBio Jun 2022Microbial nitrification is a critical process governing nitrogen availability in aquatic systems. Freshwater nitrifiers have received little attention, leaving many...
Microbial nitrification is a critical process governing nitrogen availability in aquatic systems. Freshwater nitrifiers have received little attention, leaving many unanswered questions about their taxonomic distribution, functional potential, and ecological interactions. Here, we reconstructed genomes to infer the metabolism and ecology of free-living picoplanktonic nitrifiers across the Laurentian Great Lakes, a connected series of five of Earth's largest lakes. Surprisingly, ammonia-oxidizing bacteria (AOB) related to dominated over ammonia-oxidizing archaea (AOA) at nearly all stations, with distinct ecotypes prevailing in the transparent, oligotrophic upper lakes compared to Lakes Erie and Ontario. Unexpectedly, one ecotype of encodes proteorhodopsin, which could enhance survival under conditions where ammonia oxidation is inhibited or substrate limited. Nitrite-oxidizing bacteria (NOB) " Nitrotoga" and fluctuated in dominance, with the latter prevailing in deeper, less-productive basins. Genome reconstructions reveal highly reduced genomes and features consistent with genome streamlining, along with diverse adaptations to sunlight and oxidative stress and widespread capacity for organic nitrogen use. Our findings expand the known functional diversity of nitrifiers and establish their ecological genomics in large lake ecosystems. By elucidating links between microbial biodiversity and biogeochemical cycling, our work also informs ecosystem models of the Laurentian Great Lakes, a critical freshwater resource experiencing rapid environmental change. Microorganisms play critical roles in Earth's nitrogen cycle. In lakes, microorganisms called nitrifiers derive energy from reduced nitrogen compounds. In doing so, they transform nitrogen into a form that can ultimately be lost to the atmosphere by a process called denitrification, which helps mitigate nitrogen pollution from fertilizer runoff and sewage. Despite their importance, freshwater nitrifiers are virtually unexplored. To understand their diversity and function, we reconstructed genomes of freshwater nitrifiers across some of Earth's largest freshwater lakes, the Laurentian Great Lakes. We discovered several new species of nitrifiers specialized for clear low-nutrient waters and distinct species in comparatively turbid Lake Erie. Surprisingly, one species may be able to harness light energy by using a protein called proteorhodopsin, despite the fact that nitrifiers typically live in deep dark water. Our work reveals the unique biodiversity of the Great Lakes and fills key gaps in our knowledge of an important microbial group, the nitrifiers.
Topics: Ammonia; Archaea; Bacteria; Ecosystem; Genome; Lakes; Nitrification; Nitrogen; Oxidation-Reduction; Phylogeny; Rhodopsins, Microbial
PubMed: 35435701
DOI: 10.1128/mbio.02379-21 -
The ISME Journal Sep 2022Chemolithoautotrophic nitrite-oxidising bacteria (NOB) of the genus Nitrospira contribute to nitrification in diverse natural environments and engineered systems....
Chemolithoautotrophic nitrite-oxidising bacteria (NOB) of the genus Nitrospira contribute to nitrification in diverse natural environments and engineered systems. Nitrospira are thought to be well-adapted to substrate limitation owing to their high affinity for nitrite and capacity to use alternative energy sources. Here, we demonstrate that the canonical nitrite oxidiser Nitrospira moscoviensis oxidises hydrogen (H) below atmospheric levels using a high-affinity group 2a nickel-iron hydrogenase [K = 32 nM]. Atmospheric H oxidation occurred under both nitrite-replete and nitrite-deplete conditions, suggesting low-potential electrons derived from H oxidation promote nitrite-dependent growth and enable survival during nitrite limitation. Proteomic analyses confirmed the hydrogenase was abundant under both conditions and indicated extensive metabolic changes occur to reduce energy expenditure and growth under nitrite-deplete conditions. Thermodynamic modelling revealed that H oxidation theoretically generates higher power yield than nitrite oxidation at low substrate concentrations and significantly contributes to growth at elevated nitrite concentrations. Collectively, this study suggests atmospheric H oxidation enhances the growth and survival of NOB amid variability of nitrite supply, extends the phenomenon of atmospheric H oxidation to an eighth phylum (Nitrospirota), and reveals unexpected new links between the global hydrogen and nitrogen cycles. Long classified as obligate nitrite oxidisers, our findings suggest H may primarily support growth and survival of certain NOB in natural environments.
Topics: Ammonia; Bacteria; Hydrogen; Nitrification; Nitrites; Oxidation-Reduction; Proteomics
PubMed: 35752717
DOI: 10.1038/s41396-022-01265-0 -
Biosensors Jun 2022Breath sensor technology can be used in medical diagnostics. This study aimed to build a device to measure the level of hydrogen sulfide, ammonia, acetone and alcohol in...
Breath sensor technology can be used in medical diagnostics. This study aimed to build a device to measure the level of hydrogen sulfide, ammonia, acetone and alcohol in exhaled breath of patients as well as healthy individuals. The purpose was to determine the efficacy of these gases for detection of obstructive lung disease. This study was conducted on a total of 105 subjects, where 60 subjects were patients of obstructive lung disease and 45 subjects were healthy individuals. Patients were screened by means of the Pulmonary Function Test (PFT) by a pulmonologist. The gases present in the exhaled breath of all subjects were measured. The level of ammonia (32.29 ± 20.83 ppb), (68.83 ± 35.25 ppb), hydrogen sulfide (0.50 ± 0.26 ppm), (62.71 ± 22.20 ppb), and acetone (103.49 ± 35.01 ppb), (0.66 ± 0.31 ppm) in exhaled breath were significantly different (p < 0.05) between obstructive lung disease patients and healthy individuals, except alcohol, with a p-value greater than 0.05. Positive correlation was found between ammonia w.r.t Forced Expiratory Volume in 1 s (FEV1) (r = 0.74), Forced Vital Capacity (FVC) (r = 0.61) and Forced Expiratory Flow (FEF) (r = 0.63) and hydrogen sulfide w.r.t FEV1 (r = 0.54), FVC (r = 0.41) and FEF (r = 0.37). Whereas, weak correlation was found for acetone and alcohol w.r.t FEV1, FVC and PEF. Therefore, the level of ammonia and hydrogen sulfide are useful breath markers for detection of obstructive lung disease.
Topics: Acetone; Ammonia; Breath Tests; Humans; Hydrogen Sulfide; Lung Diseases, Obstructive
PubMed: 35735555
DOI: 10.3390/bios12060409 -
Scientific Reports May 2021Ammonia has a cytotoxic effect and can therefore be used as a selection agent for enrichment of zone I hepatocytes. However, it has not yet been determined whether...
Ammonia has a cytotoxic effect and can therefore be used as a selection agent for enrichment of zone I hepatocytes. However, it has not yet been determined whether ammonia-treated hepatocyte-like cells are able to proliferate in vitro. In this study, we employed an ammonia selection strategy to purify hepatocyte-like cells that were differentiated from human embryonic stem cells (ESCs) and from induced pluripotent stem cells (iPSCs). The resistance to cytotoxicity or cell death by ammonia is likely attributable to the metabolism of ammonia in the cells. In addition to ammonia metabolism-related genes, ammonia-selected hepatocytes showed increased expression of the cytochrome P450 genes. Additionally, the ammonia-selected cells achieved immortality or at least an equivalent life span to human pluripotent stem cells without affecting expression of the liver-associated genes. Ammonia treatment in combination with in vitro propagation is useful for obtaining large quantities of hepatocytes.
Topics: Ammonia; Animals; Cell Proliferation; Cells, Cultured; Embryonic Stem Cells; Hepatocytes; Humans; Induced Pluripotent Stem Cells; Mice
PubMed: 34059723
DOI: 10.1038/s41598-021-90708-3 -
Effects of ammonia on growth performance, lipid metabolism and cecal microbial community of rabbits.PloS One 2021This study was designed to investigate the effect of ammonia on growth performance, lipid metabolism and intestinal flora of rabbits. A total of 150 female IRA rabbits...
This study was designed to investigate the effect of ammonia on growth performance, lipid metabolism and intestinal flora of rabbits. A total of 150 female IRA rabbits (35-days-old) were randomly divided into three groups including 0 ppm (CG), 10 ppm (LAC) and 30 ppm ammonia (HAC) groups for a period of 28 days. The average daily weight gain (ADG) of rabbits was significantly reduced in LAC (-17.11%; p < 0.001) and HAC groups (-17.46%; p < 0.001) as compared with the CG. Serum concentration of high density lipoprotein (HDL) and glucose (Glu) were increased in LAC (+80.95%; +45.99; p < 0.05) and HAC groups (+219.05%; +45.89; p < 0.001), while apolipoprotein A1 (apoA1) was decreased in LAC (-58.49%; p < 0.001) and HAC groups (-36.92%; p < 0.001). The structural integrity of cecum was damaged, and the thickness of mucosa and serosa were significantly decreased in LAC and HAC. The acetate, butyrate and propionate level of cecal chyme were reduced in HAC group (-21.67%; -19.82%; -30.81%; p < 0.05). Microbial diversity and burden of Firmicutes were significantly decreased, while that of pathogenic bacteria, such as Bacteroidetes, Clostridium and Proteobacteria were increased in ammonia treated groups. Spearman's correlation confirmed that burden of Ruminococcaceae_NK4A214_group showed significantly negative correlation with acetic acid (r = -0.67; p < 0.001) while Barnesiellaceae_unclassified showed significantly positive correlation with propionic acid (r = 0.50; p < 0.001). In conclusion, ammonia treatment was responsible for an imbalance of intestinal flora, which affected lipid metabolism and damaged intestinal barrier of rabbits, resulting in low growth performance due to lipid metabolism dysfunction.
Topics: Ammonia; Animal Feed; Animals; Cecum; Female; Lipid Metabolism; Microbiota; Rabbits
PubMed: 34191811
DOI: 10.1371/journal.pone.0252065