scholarly journals Enhanced nitrous oxide production in denitrifying Dechloromonas aromatica strain RCB under salt and alkaline conditions

2018 ◽  
Author(s):  
Heejoo Han ◽  
Bongkeun Song ◽  
Min Joon Song ◽  
Sukhwan Yoon
Keyword(s):  
Nitrous Oxide ◽  
Environmental Changes ◽  
Environmental Parameters ◽  
Stress Conditions ◽  
Lag Phase ◽  
Alkaline Stress ◽  
Nitrous Oxide Production ◽  
Consumption Rates ◽  
Alkaline Conditions ◽  
Dechloromonas Aromatica

Salinity and pH are important environmental parameters with direct and indirect impacts on the viability and metabolic activities of microorganisms. In this study, the effects of salt and alkaline stresses on the kinetic balance between nitrous oxide (N2O) production and consumption in the denitrification pathway of Dechloromonas aromatica strain RCB were examined. N2O accumulated transiently only in insignificant amounts at low salinity (≤0.5% NaCl) and circumneutral pH (7.0 and 7.5). Incubation at 0.7% salinity resulted in substantially longer lag phase and slower growth rate, along with the increase in the amounts of transiently accumulated N2O (15.8±2.8 μmoles N2O-N/vessel). Incubation at pH 8.0 severely inhibited growth and resulted in permanent accumulation of 29.9±1.3 μmoles N2O-N/vessel from reduction of 151±20 μmoles NO3-. The transcription analyses observed decreased nosZ/(nirS1+nirS2) ratios coinciding with N2O accumulation. The N2O consumption rates of resting D. aromatica cells subjected to the salt and alkaline stress conditions were significantly lower than the rates of N2O production from NO2- reduction at N2O / NO2- concentration of 0.1 mM, but not at a higher concentration (1.0 mM). These results indicate that alteration in N2O consumption kinetics was another cause of enhanced N2O production observed under the stress conditions. The findings in this study suggest that canonical denitrifiers may become a significant N2O source when faced with abrupt environmental changes.

scholarly journals Physiological and Biochemical Responses of Jerusalem Artichoke Seedlings to Mixed Salt-Alkali Stress Conditions

2015 ◽  
Vol 43 (2) ◽  
pp. 473-478 ◽  
Author(s):  
Shuai SHAO ◽  
Mingming QI ◽  
Shuang TAO ◽  
Jixiang LIN ◽  
Yingnan WANG ◽  
...  
Keyword(s):  
Seedling Growth ◽  
Jerusalem Artichoke ◽  
Soil Salinization ◽  
Stress Conditions ◽  
Energy Crop ◽  
Alkaline Stress ◽  
Alkali Stress ◽  
Mixed Salt ◽  
Effective Utilization ◽  
Alkaline Conditions

Soil salinization and alkalization frequently co-occur in the grassland, but little information exists concerning the mixed effects of salt-alkaline stress on plant. Jerusalem artichoke is an economically and ecologically important energy crop and also considered as a salt-tolerant species. In this study, we investigated the effects of 12 mixed salt-alkaline conditions on the seedling growth and responses of Jerusalem artichoke to such conditions. The results showed that the seedling growth decreased with the increasing salinity and pH, and the destructive effects were more markedly under the interactions of highest salinity and pH. The Na+, Mg2+ and Ca2+ concentrations were all increased with the increasing salinity and pH, but the K+ kept stable. The Cl- concentration increased when the treatment without alkali salts, and the NO3– and H2PO4- concentrations were decreased with the increasing salinity. Jerusalem artichoke seedlings enhanced organic acids and proline to supply the shortage of inorganic anions and cope with osmotic stress from the high Na+ concentration. Above results show that the toxicity effects of the interactions of salt stress and alkali stress on plant is much greater than that only salt or alkali stress. A better understanding of the seedlings of Jerusalem artichoke under mixed salt-alkali stress conditions should facilitate the effective utilization of this species under such complex environment in Northeast China.

scholarly journals Thiol-based switching mechanisms of stress-sensing chaperones

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Kathrin Ulrich ◽  
Blanche Schwappach ◽  
Ursula Jakob
Keyword(s):  
Oxidative Stress ◽  
Environmental Changes ◽  
Stress Conditions ◽  
Stress Exposure ◽  
Atp Levels ◽  
Protein Functions ◽  
Activation Mechanisms ◽  
Client Proteins ◽  
Stress Sensing ◽  
Redox Switches

AbstractThiol-based redox switches evolved as efficient post-translational regulatory mechanisms that enable individual proteins to rapidly respond to sudden environmental changes. While some protein functions need to be switched off to save resources and avoid potentially error-prone processes, protective functions become essential and need to be switched on. In this review, we focus on thiol-based activation mechanisms of stress-sensing chaperones. Upon stress exposure, these chaperones convert into high affinity binding platforms for unfolding proteins and protect cells against the accumulation of potentially toxic protein aggregates. Their chaperone activity is independent of ATP, a feature that becomes especially important under oxidative stress conditions, where cellular ATP levels drop and canonical ATP-dependent chaperones no longer operate. Vice versa, reductive inactivation and substrate release require the restoration of ATP levels, which ensures refolding of client proteins by ATP-dependent foldases. We will give an overview over the different strategies that cells evolved to rapidly increase the pool of ATP-independent chaperones upon oxidative stress and provide mechanistic insights into how stress conditions are used to convert abundant cellular proteins into ATP-independent holding chaperones.

Nitrous oxide production in two forested watersheds exhibiting symptoms of nitrogen saturation

1998 ◽  
Vol 28 (11) ◽  
pp. 1723-1732 ◽  
Author(s):  
William T Peterjohn ◽  
Richard J McGervey ◽  
Alan J Sexstone ◽  
Martin J Christ ◽  
Cassie J Foster ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Nitrogen Saturation ◽  
N Cycling ◽  
Woody Vegetation ◽  
N Saturation ◽  
Relative Importance ◽  
Forested Watersheds ◽  
Total N ◽  
Nitrous Oxide Production ◽  
Poorly Drained Soils

A major concern about N saturation is that it may increase the production of a strong greenhouse gas, nitrous oxide (N2O). We measured N2O production in two forested watersheds, a young, fertilized forest (WS 3) and an older, unfertilized forest (WS 4), to (i) assess the importance of N2O production in forests showing symptoms of N saturation; (ii) estimate the contribution of chemoautrophic nitrification to total N2O production; and (iii) examine the relative importance of factors that may control N2O production. During the study period, mean monthly rates of N2O production (3.41-11.42 µ N ·m-2·h-1) were consistent with measurements from other well-drained forest soils but were much lower than measurements from N-rich sites with poorly drained soils. Chemoautotrophic nitrification was important in both watersheds, accounting for 60% (WS 3) and 40% (WS 4) of total N2O production. In WS 3, N2O production was enhanced by additions of CaCO3 and may be constrained by low soil pH. In WS 4, N2O production on south-facing slopes was exceptionally low, constrained by low NO3 availability, and associated with a distinct assemblage of woody vegetation. From this observation, we hypothesize that differences in vegetation can influence N cycling rates and susceptibility to N saturation.

scholarly journals Low nitrous oxide production through nitrifier-denitrification in intermittent-feed high-rate nitritation reactors

2017 ◽  
Vol 123 ◽  
pp. 429-438 ◽  
Author(s):  
Qingxian Su ◽  
Chun Ma ◽  
Carlos Domingo-Félez ◽  
Anne Sofie Kiil ◽  
Bo Thamdrup ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
High Rate ◽  
Oxide Production ◽  
Nitrifier Denitrification ◽  
Nitrous Oxide Production

scholarly journals Variability in larval gut pH regulation defines sensitivity to ocean acidification in six species of the Ambulacraria superphylum

2017 ◽  
Vol 284 (1864) ◽  
pp. 20171066 ◽  
Author(s):  
Marian Hu ◽  
Yung-Che Tseng ◽  
Yi-Hsien Su ◽  
Etienne Lein ◽  
Hae-Gyeong Lee ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Large Scale ◽  
Environmental Changes ◽  
Ph Regulation ◽  
Gastric Ph ◽  
Differential Sensitivity ◽  
Larval Stages ◽  
Regulatory Systems ◽  
Alkaline Conditions ◽  
Gut Ph

The unusual rate and extent of environmental changes due to human activities may exceed the capacity of marine organisms to deal with this phenomenon. The identification of physiological systems that set the tolerance limits and their potential for phenotypic buffering in the most vulnerable ontogenetic stages become increasingly important to make large-scale projections. Here, we demonstrate that the differential sensitivity of non-calcifying Ambulacraria (echinoderms and hemichordates) larvae towards simulated ocean acidification is dictated by the physiology of their digestive systems. Gastric pH regulation upon experimental ocean acidification was compared in six species of the superphylum Ambulacraria. We observed a strong correlation between sensitivity to ocean acidification and the ability to regulate gut pH. Surprisingly, species with tightly regulated gastric pH were more sensitive to ocean acidification. This study provides evidence that strict maintenance of highly alkaline conditions in the larval gut of Ambulacraria early life stages may dictate their sensitivity to decreases in seawater pH. These findings highlight the importance of identifying and understanding pH regulatory systems in marine larval stages that may contribute to substantial energetic challenges under near-future ocean acidification scenarios.

scholarly journals Abscisic Acid Priming Creates Alkaline Tolerance in Alfalfa Seedlings (Medicago sativa L.)

Agriculture ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 608
Author(s):  
Tian-Jiao Wei ◽  
Ming-Ming Wang ◽  
Yang-Yang Jin ◽  
Guo-Hui Zhang ◽  
Miao Liu ◽  
...  
Keyword(s):  
Abscisic Acid ◽  
Molecular Mechanisms ◽  
Leaf Damage ◽  
Alkaline Stress ◽  
Acid Pretreatment ◽  
Solution Ph ◽  
Expression Of Genes ◽  
Alkaline Tolerance ◽  
Alkaline Conditions ◽  
Medicago Sativa L

Soil alkalization triggers ion toxicity and osmotic and alkaline (high pH) stresses in plants, damaging their growth and productivity. Therefore, we investigated whether priming with abscisic acid (ABA) increases the tolerance of alfalfa seedlings to alkaline stress, and then examined the underlying molecular mechanisms. Alfalfa seedlings were pretreated with ABA (10 μM) for 16 h and then subjected to alkaline stress using a 15 mM Na2CO3 solution (pH 10.87). Compared with the control, ABA pretreatment significantly alleviated leaf damage and improved the fresh weight, water content, and survival rate of alfalfa seedlings under alkaline conditions. Abscisic acid pretreatment reduced accumulation of reactive oxygen species (ROS), increased activities of the antioxidant enzymes superoxide dismutase (SOD) and peroxidase (POD), maintained higher ratios of K+/Na+, Ca2+/Na+, and Mg2+/Na+, and increased accumulation of proline. In addition, ABA upregulated the expression of genes involved in proline biosynthesis (P5CS) and the sequestration of Na+ in vacuoles (NHX1 and AVP) under alkaline conditions. Abscisic acid priming increased tolerance to alkaline stress by maintaining homeostasis of ROS and metal ions and upregulating osmoprotection and the expression of stress tolerance-related genes.

Validation of Analytical Methods for Tacrolimus Determination in Poly(ε-caprolactone) Nanocapsules and Identification of Drug Degradation Products

2021 ◽  
Vol 21 (12) ◽  
pp. 5920-5928
Author(s):  
Guilherme A. Camargo ◽  
Amanda M. Lyra ◽  
Fernanda M. Barboza ◽  
Barbara C. Fiorin ◽  
Flávio L. Beltrame ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
High Performance ◽  
Degradation Products ◽  
Multiple Reaction Monitoring ◽  
Forced Degradation ◽  
Alkaline Stress ◽  
Drug Degradation ◽  
Relative Standard ◽  
Polymeric Nanocapsules ◽  
Alkaline Conditions

The aim of this paper was to use chromatographic tools for validating an analytical method for the tacrolimus (TAC) determination in polymeric nanocapsules and for identifying the drug degradation products after alkaline stress. A rapid Ultra-High-Performance Liquid Chromatography coupled with photo-diode array (UHPLC-PDA) method was successfully performed using the following chromatographic conditions: the Shimadzu Shim-pack XR-ODS III C18 column (100 mm×2.00 mm, 2.2 μm), the mobile phase consisting of methanol and acidified ultrapure water (89:11 v/v), the flow rate of 0.55 mL·min−1, and the ultraviolet (UV) detection at 235 nm. This method was validated as per International Council for Harmonisation (ICH) guidelines. In addition, a TAC forced degradation assay was carried out after alkaline stress and its degradation products were investigated using Liquid Chromatography coupled tandem mass spectroscopy (LC-MS/MS). The calibration curve was linear in the range of 100.0–300.0 μg·mL−1 (r >0.9999). Accuracy was confirmed by the TAC recovery of 96.55 to 98.19%. Precision (intraday and interday) were demonstrated by relative standard deviation lower than 0.89% and 3.25%, respectively. Selectivity and robustness were also proved. The method developed it was successfully applied to quantify TAC from polymeric nanocapsules, showing a high loading efficiency rate (>96.47%). The main drug degradation product observed in a multiple reaction monitoring (MRM) experiment was m/z 844, confirming the susceptibility of TAC under alkaline conditions; this finding was first time described.

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