THE EFFECTS OF NITRATE, AMMONIUM AND TEMPERATURE ON NITRATE REDUCTASE ACTIVITY IN SPHAGNUM SPECIES
1Department of Botany, The University, Manchester M13 9PL, UK.
The New Phytologist
|April 20, 2021
Summary
Nitrate reductase activity in Sphagnum mosses is influenced by nitrogen availability. Ammonium can repress enzyme activity, suggesting complex interactions affecting nitrate uptake and assimilation.
Area of Science:
- Plant Physiology
- Environmental Science
- Biochemistry
Background:
- Nitrate reductase is a key enzyme in nitrogen assimilation.
- Sphagnum mosses are important in ombrotrophic ecosystems.
- Understanding nitrogen effects on enzyme activity is crucial for ecological monitoring.
Purpose of the Study:
- To investigate the impact of inorganic nitrogen on nitrate reductase activity in Sphagnum species.
- To determine how nitrate and ammonium availability affect enzyme induction and repression.
- To assess the potential of nitrate reductase activity as a bioindicator for atmospheric nitrate deposition.
Main Methods:
- Field and laboratory experiments were conducted.
- Nitrate reductase activity was measured in Sphagnum capillifolium and Sphagnum fuscum.
- Plants were subjected to varying concentrations and frequencies of nitrate and ammonium treatments.
Main Results:
- Nitrate reductase activity was highest in the moss capitulum and decreased down the stem.
- Enzyme activity was substrate-inducible, correlating with nitrate concentration.
- Repeated ammonium application repressed nitrate reductase activity, potentially affecting nitrate uptake and assimilation.
Conclusions:
- Nitrogen availability, particularly ammonium, significantly impacts nitrate reductase activity in Sphagnum.
- The interaction between nitrate and ammonium supply influences enzyme induction patterns.
- Nitrate reductase activity shows potential as a bioindicator for monitoring atmospheric nitrogen deposition in ombrotrophic environments.
Related Concept Videos
01:22Inorganic Nitrogen Assimilation
224
Nitrogen is an essential element in biological systems, forming a crucial component of proteins, nucleic acids, and other cellular constituents. Many bacteria and archaea acquire nitrogen in the form of nitrate (NO₃⁻) or ammonia (NH₃), which are then assimilated into biomolecules through specific enzymatic pathways.Assimilatory Nitrate ReductionWhen nitrate enters the cell, it undergoes a two-step reduction process known as assimilatory nitrate reduction. Initially, the enzyme...
224
01:202° Amines to N-Nitrosamines: Reaction with NaNO2
4.8K
Secondary amines react with nitrous acid to form N-nitrosamines, as depicted in Figure 1. Nitrous acid, a weak and unstable acid, is formed in situ from an aqueous solution of sodium nitrite and strong acids, such as hydrochloric acid or sulfuric acid, in cold conditions. In the presence of an acid, the nitrous acid gets protonated. The subsequent loss of water results in the formation of the electrophile known as nitrosonium ion.
4.8K
01:27Factors Influencing Microbial Growth: Temperature
636
Microorganisms display remarkable adaptations, enabling them to thrive in diverse ecological niches across a wide range of temperatures. Temperature profoundly influences microbial growth by affecting enzymatic activity, membrane fluidity, and other cellular processes.Each microorganism operates within a specific temperature range defined by three cardinal points: minimum, optimum, and maximum. Below the minimum temperature, membranes lose fluidity, halting transport processes. Above the...
636
02:45Responses to Heat and Cold Stress
14.1K
Every organism has an optimum temperature range within which healthy growth and physiological functioning can occur. At the ends of this range, there will be a minimum and maximum temperature that interrupt biological processes.
14.1K
01:21Hyperthermophilic Bacteria
207
Domain Bacteria includes some unique hyperthermophilic species. They exhibit remarkable adaptations that enable survival in extreme environments.Thermotoga species are rod-shaped, gram-negative, non-sporulating hyperthermophiles that form a sheath-like envelope called a toga. They ferment sugars or starch, producing lactate, acetate, CO₂, and H₂, and can also grow via anaerobic respiration using H₂ and ferric iron. Found in hot springs and hydrothermal vents, over 20% of their...
207
01:15Metabolism of Chemolithotrophs
410
Chemolithotrophs are microorganisms that obtain energy by oxidizing inorganic molecules such as hydrogen gas (H₂), ammonia (NH₃), reduced sulfur compounds (H₂S, S²⁻), and ferrous iron (Fe²⁺). Unlike heterotrophic organisms that rely on organic carbon, chemolithotrophs transfer electrons from these inorganic donors to the electron transport chain (ETC), generating a proton motive force (PMF) that drives ATP synthesis through oxidative phosphorylation.
410