scholarly journals The hypoxia-reoxygenation stress in plants

2020 ◽  
Author(s):  
José León ◽  
Mari Cruz Castillo ◽  
Beatriz Gayubas
Keyword(s):  
Cell Damage ◽  
Global Climate ◽  
Atmospheric Conditions ◽  
Post Translational Modifications ◽  
Molecular Events ◽  
Proteolytic Pathway ◽  
Adverse Environmental Conditions ◽  
Regulatory Functions ◽  
O2 Sensing ◽  
Hypoxia Reoxygenation

Abstract Plants are very plastic in adapting growth and development to changing adverse environmental conditions. This feature will be essential for plants to survive climate changes characterized by extreme temperatures and rainfall. Although plants require molecular oxygen (O2) to live, they can overcome transient low O2 conditions (hypoxia) until return to standard 21% O2 atmospheric conditions (normoxia). After heavy rainfall, submerged plants in flooded lands undergo transient hypoxia until water recedes and normoxia is recovered. The accumulated information on the physiological and molecular events occurring during the hypoxia phase contrasts with the limited knowledge on the reoxygenation process after hypoxia, which has been often overlooked in many studies in plants. Phenotypic alterations during recovery are due to potentiated oxidative stress generated by simultaneous reoxygenation and reillumination leading to cell damage. Besides processes like N-degron proteolytic pathway-mediated O2 sensing, or mitochondria-driven metabolic alterations, other molecular events controlling gene expression have been recently proposed as key regulators of hypoxia and reoxygenation. RNA regulatory functions, chromatin remodeling, protein synthesis and post-translational modifications must all be deeply studied in the next years to improve our knowledge on hypoxia-reoxygenation transition in plants, a topic with relevance in agricultural biotechnology in the context of global climate change.

O2-. release by activated Kupffer cells upon hypoxia-reoxygenation

1991 ◽  
Vol 261 (4) ◽  
pp. G602-G607 ◽  
Author(s):  
B. Rymsa ◽  
J. F. Wang ◽  
H. de Groot
Keyword(s):  
Nadph Oxidase ◽  
Kupffer Cells ◽  
Cell Injury ◽  
Cell Damage ◽  
Primary Cultures ◽  
Time Lag ◽  
Specific Inhibitor ◽  
Significant Difference ◽  
Reoxygenation Injury ◽  
Hypoxia Reoxygenation

Primary cultures of rat liver Kupffer cells generated large amounts of superoxide anion radical (O2-.) when subjected to reoxygenation after a hypoxic period of at least 2 h. O2-. formation reached its maximum rate of approximately 25 nmol/10(6) cells within 1 h after reoxygenation. Two to four hours after reoxygenation, the number of injured cells began to increase and after 10 h approximately 60% of the cells were dead. During the period of O2-. release no significant difference in cell viability was observed between reoxygenated and hypoxically incubated cells, indicating a distinct time lag between O2-. release and onset of cell damage. Addition of diphenyliodonium, a specific inhibitor of the neutrophilic NADPH oxidase, to the Kupffer cells just before reoxygenation diminished both O2-. formation and cell injury up to 70%. Reoxygenation injury was completely prevented when superoxide dismutase and catalase were added immediately before reoxygenation. The results indicate that Kupffer cells subjected to hypoxia-reoxygenation generate a burst of reactive oxygen species and that this kind of "activation," probably by activating the NADPH oxidase, contributes to the self-destruction of the cells.

scholarly journals A biogenic secondary organic aerosol source of cirrus ice nucleating particles

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Martin J. Wolf ◽  
Yue Zhang ◽  
Maria A. Zawadowicz ◽  
Megan Goodell ◽  
Karl Froyd ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Secondary Organic Aerosol ◽  
Global Climate ◽  
Compositional Analysis ◽  
Field Measurements ◽  
Organic Aerosol ◽  
Cloud Formation ◽  
Ambient Atmosphere ◽  
Atmospheric Conditions ◽  
Mass Fractions

Abstract Atmospheric ice nucleating particles (INPs) influence global climate by altering cloud formation, lifetime, and precipitation efficiency. The role of secondary organic aerosol (SOA) material as a source of INPs in the ambient atmosphere has not been well defined. Here, we demonstrate the potential for biogenic SOA to activate as depositional INPs in the upper troposphere by combining field measurements with laboratory experiments. Ambient INPs were measured in a remote mountaintop location at –46 °C and an ice supersaturation of 30% with concentrations ranging from 0.1 to 70 L–1. Concentrations of depositional INPs were positively correlated with the mass fractions and loadings of isoprene-derived secondary organic aerosols. Compositional analysis of ice residuals showed that ambient particles with isoprene-derived SOA material can act as depositional ice nuclei. Laboratory experiments further demonstrated the ability of isoprene-derived SOA to nucleate ice under a range of atmospheric conditions. We further show that ambient concentrations of isoprene-derived SOA can be competitive with other INP sources. This demonstrates that isoprene and potentially other biogenically-derived SOA materials could influence cirrus formation and properties.

scholarly journals Strong asymmetry of hemispheric climates during MIS-13 inferred from correlating China loess and Antarctica ice records

2009 ◽  
Vol 5 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Z. T. Guo ◽  
A. Berger ◽  
Q. Z. Yin ◽  
L. Qin
Keyword(s):  
Northern Hemisphere ◽  
Asian Indian ◽  
Global Climate ◽  
Global Scale ◽  
Atmospheric Conditions ◽  
Inter Tropical Convergence Zone ◽  
Asian Winter Monsoon ◽  
Northern Summer ◽  
Northern High Latitude ◽  
Strong Asymmetry

Abstract. We correlate the China loess and Antarctica ice records to address the inter-hemispheric climate link over the past 800 ka. The results show a broad coupling between Asian and Antarctic climates at the glacial-interglacial scale. However, a number of decoupled aspects are revealed, among which marine isotope stage (MIS) 13 exhibits a strong anomaly compared with the other interglacials. It is characterized by unusually positive benthic oxygen (δ18O) and carbon isotope (δ13C) values in the world oceans, cooler Antarctic temperature, lower summer sea surface temperature in the South Atlantic, lower CO2 and CH4 concentrations, but by extremely strong Asian, Indian and African summer monsoons, weakest Asian winter monsoon, and lowest Asian dust and iron fluxes. Pervasive warm conditions were also evidenced by the records from northern high-latitude regions. These consistently indicate a warmer Northern Hemisphere and a cooler Southern Hemisphere, and hence a strong asymmetry of hemispheric climates during MIS-13. Similar anomalies of lesser extents also occurred during MIS-11 and MIS-5e. Thus, MIS-13 provides a case that the Northern Hemisphere experienced a substantial warming under relatively low concentrations of greenhouse gases. It suggests that the global climate system possesses a natural variability that is not predictable from the simple response of northern summer insolation and atmospheric CO2 changes. During MIS-13, both hemispheres responded in different ways leading to anomalous continental, marine and atmospheric conditions at the global scale. The correlations also suggest that the marine δ18O record is not always a reliable indicator of the northern ice-volume changes, and that the asymmetry of hemispheric climates is one of the prominent factors controlling the strength of Asian, Indian and African monsoon circulations, most likely through modulating the position of the inter-tropical convergence zone (ITCZ) and land-sea thermal contrasts.

scholarly journals Seasonal changes in the altitudinal distribution of nocturnally migrating birds during autumn migration

2015 ◽  
Vol 2 (12) ◽  
pp. 150347 ◽  
Author(s):  
Frank A. La Sorte ◽  
Wesley M. Hochachka ◽  
Andrew Farnsworth ◽  
Daniel Sheldon ◽  
Benjamin M. Van Doren ◽  
...  
Keyword(s):  
Migratory Birds ◽  
Global Climate ◽  
Polar Front ◽  
Migratory Bird ◽  
Atmospheric Conditions ◽  
Altitudinal Distribution ◽  
Long Distance ◽  
Bird Populations ◽  
Intermediate Distance ◽  
Migrating Birds

Wind plays a significant role in the flight altitudes selected by nocturnally migrating birds. At mid-latitudes in the Northern Hemisphere, atmospheric conditions are dictated by the polar-front jet stream, whose amplitude increases in the autumn. One consequence for migratory birds is that the region’s prevailing westerly winds become progressively stronger at higher migration altitudes. We expect this seasonality in wind speed to result in migrants occupying progressively lower flight altitudes, which we test using density estimates of nocturnal migrants at 100 m altitudinal intervals from 12 weather surveillance radar stations located in the northeastern USA. Contrary to our expectations, median migration altitudes deviated little across the season, and the variance was lower during the middle of the season and higher during the beginning and especially the end of the season. Early-season migrants included small- to intermediate-sized long-distance migrants in the orders Charadriiformes and Passeriformes, and late-season migrants included large-bodied and intermediate-distance migrants in the order Anseriformes. Therefore, seasonality in the composition of migratory species, and related variation in migration strategies and behaviours, resulted in a convex–concave bounded distribution of migration altitudes. Our results provide a basis for assessing the implications for migratory bird populations of changes in mid-latitude atmospheric conditions probably occurring under global climate change.

scholarly journals Antarctic regional modelling of atmospheric, sea-ice and oceanic processes and validation with observations

2000 ◽  
Vol 31 ◽  
pp. 348-352 ◽  
Author(s):  
David A. Bailey ◽  
Amanda H. Lynch
Keyword(s):  
Sea Ice ◽  
Global Climate ◽  
Regional Climate ◽  
Climate System ◽  
The Arctic ◽  
Small Scale ◽  
Atmospheric Conditions ◽  
Regional Modelling ◽  
Climate System Model ◽  
The Antarctic

AbstractHigh-latitude interactions of local-scale processes in the atmosphere-ice-ocean system have effects on the local, Antarctic and global climate. Phenomena including polynyas and leads are examples of such interactions which, when combined, have a significant impact on larger scales. These small-scale features, which are typically parameterized in global models, can be explicitly simulated using high-resolution regional climate system models. As such, the study of these interactions is well suited to a regional model approach and is considered here using the Arctic Regional Climate System Model (ARCSyM). This model has been used for many simulations in the Arctic, and is now implemented for the Antarctic. Observations of such processes in the Antarctic are limited, which makes model validation difficult. However, using the best available observations for an annual cycle, we have determined a suite of model parameterization which allows us to reasonably simulate the Antarctic climate. This work considers a fine-resolution (20 km) simulation in the Cosmonaut Sea region, with the eventual goal of elucidating the mechanisms in the formation and maintenance of the sensible-heat polynya which is a regular occurrence in this area. It was found in an atmosphere-sea-ice simulation that the ocean plays an important role in regulating the sea-ice cover in this region in compensating for the cold atmospheric conditions.

scholarly journals γ-Aminobutyrate (GABA) Regulated Plant Defense: Mechanisms and Opportunities

Plants ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1939
Author(s):  
Barry J. Shelp ◽  
Morteza Soleimani Aghdam ◽  
Edward J. Flaherty
Keyword(s):  
Biotic Stress ◽  
Metal Tolerance ◽  
Genetic Manipulation ◽  
Cell Damage ◽  
Global Climate ◽  
Heavy Metal Tolerance ◽  
Hypoxia Tolerance ◽  
K Channel ◽  
Enzymatic Antioxidants ◽  
Protein Amino Acid

Global climate change and associated adverse abiotic and biotic stress conditions affect plant growth and development, and agricultural sustainability in general. Abiotic and biotic stresses reduce respiration and associated energy generation in mitochondria, resulting in the elevated production of reactive oxygen species (ROS), which are employed to transmit cellular signaling information in response to the changing conditions. Excessive ROS accumulation can contribute to cell damage and death. Production of the non-protein amino acid γ-aminobutyrate (GABA) is also stimulated, resulting in partial restoration of respiratory processes and energy production. Accumulated GABA can bind directly to the aluminum-activated malate transporter and the guard cell outward rectifying K+ channel, thereby improving drought and hypoxia tolerance, respectively. Genetic manipulation of GABA metabolism and receptors, respectively, reveal positive relationships between GABA levels and abiotic/biotic stress tolerance, and between malate efflux from the root and heavy metal tolerance. The application of exogenous GABA is associated with lower ROS levels, enhanced membrane stability, changes in the levels of non-enzymatic and enzymatic antioxidants, and crosstalk among phytohormones. Exogenous GABA may be an effective and sustainable tolerance strategy against multiple stresses under field conditions.

scholarly journals Molecular engineering of an efficient four-domain DAF-MCP chimera reveals the presence of functional modularity in RCA proteins

2019 ◽  
Vol 116 (20) ◽  
pp. 9953-9958 ◽  
Author(s):  
Hemendra Singh Panwar ◽  
Hina Ojha ◽  
Payel Ghosh ◽  
Sagar H. Barage ◽  
Sunil Raut ◽  
...  
Keyword(s):  
Complement Activation ◽  
Cell Damage ◽  
Alternative Pathway ◽  
Molecular Engineering ◽  
Dual Function ◽  
Complement Control Protein ◽  
Regulators Of Complement Activation ◽  
Functional Units ◽  
Regulatory Functions ◽  
The Complement System

The complement system is highly efficient in targeting pathogens, but lack of its apposite regulation results in host-cell damage, which is linked to diseases. Thus, complement activation is tightly regulated by a series of proteins, which primarily belong to the regulators of complement activation (RCA) family. Structurally, these proteins are composed of repeating complement control protein (CCP) domains where two to four successive domains contribute to the regulatory functions termed decay-accelerating activity (DAA) and cofactor activity (CFA). However, the precise constitution of the functional units and whether these units can be joined to form a larger composition with dual function have not been demonstrated. Herein, we have parsed the functional units for DAA and CFA by constructing chimeras of the decay-accelerating factor (DAF) that exhibits DAA and membrane cofactor protein (MCP) that exhibits CFA. We show that in a four-CCP framework, a functional unit for each of the regulatory activities is formed by only two successive CCPs wherein each participates in the function, albeit CCP2 has a bipartite function. Additionally, optimal activity requires C-terminal domains that enhance the avidity of the molecule for C3b/C4b. Furthermore, by composing a four-CCP DAF-MCP chimera with robust CFA (for C3b and C4b) and DAA (for classical and alternative pathway C3 convertases), named decay cofactor protein, we show that CCP functional units can be linked to design a dual-activity regulator. These data indicate that the regulatory determinants for these two biological processes are distinct and modular in nature.

scholarly journals Epigenetic Mechanisms of Inflammasome Regulation

2020 ◽  
Vol 21 (16) ◽  
pp. 5758 ◽  
Author(s):  
Giulia Poli ◽  
Consuelo Fabi ◽  
Marina Maria Bellet ◽  
Claudio Costantini ◽  
Luisa Nunziangeli ◽  
...  
Keyword(s):  
Noncoding Rna ◽  
Molecular Mechanisms ◽  
Fungal Infections ◽  
Cell Damage ◽  
Epigenetic Mechanisms ◽  
Cpg Dna ◽  
Post Translational Modifications ◽  
Inflammatory Pathways ◽  
Complementary Mechanism

The innate immune system represents the host’s first-line defense against pathogens, dead cells or environmental factors. One of the most important inflammatory pathways is represented by the activation of the NOD-like receptor (NLR) protein family. Some NLRs induce the assembly of large caspase-1-activating complexes called inflammasomes. Different types of inflammasomes have been identified that can respond to distinct bacterial, viral or fungal infections; sterile cell damage or other stressors, such as metabolic imbalances. Epigenetic regulation has been recently suggested to provide a complementary mechanism to control inflammasome activity. This regulation can be exerted through at least three main mechanisms, including CpG DNA methylation, histones post-translational modifications and noncoding RNA expression. The repression or promotion of expression of different inflammasomes (NLRP1, NLRP2, NLRP3, NLRP4, NLRP6, NLRP7, NLRP12 and AIM2) through epigenetic mechanisms determines the development of pathologies with variable severity. For example, our team recently explored the role of microRNAs (miRNAs) targeting and modulating the components of the inflammasome as potential biomarkers in bladder cancer and during therapy. This suggests that the epigenetic control of inflammasome-related genes could represent a potential target for further investigations of molecular mechanisms regulating inflammatory pathways.

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