Reduced N‐Limitation and Increased In‐Stream Productivity of Autotrophic Biofilms 5 and 15 Years After Severe Wildfire

2021 ◽  
Author(s):  
Allison E. Rhea ◽  
Tim P. Covino ◽  
Charles C. Rhoades
Keyword(s):  
N Limitation ◽  
Autotrophic Biofilms ◽  
Stream Productivity

Modulation of photosynthesis and inorganic carbon acquisition in a marine microalga by nitrogen, iron, and light availability

2005 ◽  
Vol 83 (7) ◽  
pp. 917-928 ◽  
Author(s):  
Erica B Young ◽  
John Beardall
Keyword(s):  
Inorganic Carbon ◽  
Dunaliella Tertiolecta ◽  
Initial Slope ◽  
Carbon Concentrating Mechanism ◽  
High Affinity ◽  
N Limitation ◽  
Marine Microalga ◽  
Concentrating Mechanism ◽  
Energy Limitation ◽  
Use Efficiency

The marine microalga Dunaliella tertiolecta Butcher expresses a high affinity for dissolved inorganic carbon (DIC) through a carbon-concentrating mechanism (CCM), known to be influenced by CO2 availability and instantaneous light supply. However, the regulation by light and nutrient supply during growth is less understood, although N and Fe limitation impose an energy limitation by compromising the photosynthetic apparatus. Dunaliella tertiolecta was grown under steady-state conditions of limited light, N, and Fe availability, and the affinity for DIC was measured under saturating light. High affinity DIC uptake capacity was maintained by D. tertiolecta under all growth-limiting conditions, but was modulated in response to the limiting resource. Affinity of photosynthesis for DIC(k0.5) was significantly reduced in cells grown under low light, both in turbidostats and in batch culture (p ≤ 0.03), although cell-normalized Pmax was not significantly affected. In contrast, N and Fe limitation resulted in a significant reduction in cell chlorophyll, Pmax, and maximum photosystem II quantum yield (Fv/Fm), but the affinity for DIC was enhanced with increasing N or Fe stress. While the affinity for DIC improved with increasing N stress (k0.5 < 17.8 µM at µ = 0.27 d–1 versus k0.5 > 26 µM at µ ≥ 0.77 d–1), light use efficiency (α) was impaired under N limitation, suggesting a trade-off between light harvesting capacity and active DIC uptake. Stable C isotope analysis of Fe-limited cells confirmed a lower fractionation by the most Fe-limited cells, consistent with the k0.5 data and more active DIC acquisition (δ13C = –19.56 at µ = 0.27 d–1 cf. δ13C = –26.28 at µ = 0.77 d–1). Assessment of affinity for DIC using k0.5 was supported by the close fit of P versus DIC curves to Michaelis–Menten kinetics; with the high DIC affinity of D. tertiolecta, there was poor resolution in the initial slope of the P versus DIC curve as a parameter of affinity for DIC. Enhanced DIC uptake efficiency under Fe and N limitation may relate to improved resource-use efficiency conferred by CCM activity.Key words: algae, carbon-concentrating mechanism, iron, light, nitrogen, nutrient limitation, photosynthesis.

Interactive effects of nitrogen and irradiance on growth and partitioning of dry mass and nitrogen in young tomato plants

2002 ◽  
Vol 29 (11) ◽  
pp. 1319 ◽  
Author(s):  
Corine C. de Groot ◽  
Leo F. M. Marcelis ◽  
Riki van den Boogaard ◽  
Hans Lambers
Keyword(s):  
Leaf Area ◽  
Dry Mass ◽  
High Irradiance ◽  
Interactive Effects ◽  
Tomato Plants ◽  
N Limitation ◽  
N Supply ◽  
N Concentration ◽  
Growth Irradiance ◽  
Dry Mass Partitioning

The interactive effects of irradiance and N on growth of young tomato plants (Lycopersicon esculentum Mill.) were studied. Plants were grown at 70 or 300 μmol photons m–2 s–1, hereafter referred to as 'low' and 'high' irradiance, and at a range of exponential N supply rates (70–370 mg g–1 d–1) or at a constant concentration in the nutrient solution of 12 mM NO3–. At both irradiance levels, leaf area ratio was more important than net assimilation rate (NAR) in explaining effects of N on growth at mild N limitation. However, at severe N limitation, NAR became the most important parameter, as indicated by calculated growth response coefficients. Furthermore, this study shows that N supply and growth irradiance interacted strongly. The decrease of specific leaf area with increasing N limitation and increasing growth irradiance correlated with increasing leaf dry mass percentage and starch concentration. Furthermore, at low irradiance, plants partitioned more dry mass to the stem. Dry mass partitioning to roots increased with decreasing plant N concentration, and this relation appeared to be independent of irradiance. Shading increased plant N concentration and decreased dry mass partitioning to roots. Also, the relationship between plant N concentration and N partitioning to different plant organs was largely independent of growth irradiance.

scholarly journals Emiliania huxleyi endures N-limitation with an efficient metabolic budgeting and effective ATP synthesis

BMC Genomics ◽  
2014 ◽  
Vol 15 (1) ◽  
pp. 1051 ◽  
Author(s):  
Sebastian D Rokitta ◽  
Peter Von Dassow ◽  
Björn Rost ◽  
Uwe John
Keyword(s):  
Atp Synthesis ◽  
Emiliania Huxleyi ◽  
N Limitation

scholarly journals Influence of N-limitation on Malic Enzyme Isoforms and Lipogenesis of Cunninghamella bainieri 2A1

2014 ◽  
Vol 67 (1) ◽  
Author(s):  
Aidil Abdul Hamid ◽  
Shuwahida Shuib ◽  
Ekhlass M. Taha ◽  
Othman Omar ◽  
Mohd Sahaid Khalil ◽  
...  
Keyword(s):  
Lipid Content ◽  
Lipid Accumulation ◽  
Malic Enzyme ◽  
Lipid Synthesis ◽  
Lower Activity ◽  
Ammonium Tartrate ◽  
Ammonium Ions ◽  
Activity Staining ◽  
N Limitation ◽  
Enzyme Isoforms

The influence of the presence of ammonium ions in growth culture on malic enzyme (ME) isoforms activity and lipogenesis in Cunninghamella bainieri 2A1 was investigated. The fungus was cultivated in a nitrogen-limiting medium for 120 h at 30oC under two conditions. One of the cultures was intermittently fed with ammonium tartrate to maintain the ammonium concentrations above 0.5 g/L. The second culture was performed without any feeding to allow N limitation, thus promoting lipid accumulation. Activity staining of ME isoforms was carried out for both cultures. The culture which was not intermittently fed with ammonium tartrate achieved a maximum lipid content of 35% (g/g biomass) at 48 h. This culture possessed five ME isoforms (A, B, C, D and E) with isoform E showing a parallel correlation to lipid accumulation profile. In contrast, intensity of bands representing isoform D decreased as lipid accumulated. No appreciable differences of all other isoforms were observed. However, the culture which was intermittently fed with ammonium tartrate, accumulated only up to 16% lipid (g/g biomass). All isoforms were present but with a more pronounced activity of isoform D and a lower activity of isoform E was observed. These findings support further evidence that isoform E is the key isoform for lipid synthesis in C. bainieri 2A1.

The role of N2 fixation in alleviating N limitation in wetland metaphyton: enzymatic, isotopic, and elemental evidence

2007 ◽  
Vol 84 (2) ◽  
pp. 207-218 ◽  
Author(s):  
J. Thad Scott ◽  
Robert D. Doyle ◽  
Jeffrey A. Back ◽  
S. I. Dworkin
Keyword(s):  
N2 Fixation ◽  
N Limitation

Rising CO2 and warming lead to declining global canopy demand for nitrogen

2021 ◽  
Author(s):  
Ning Dong ◽  
Iain Colin Prentice ◽  
Ian Wright ◽  
Xiangzhong Luo ◽  
Nick Smith
Keyword(s):  
Photosynthetic Capacity ◽  
Carbon Uptake ◽  
Global Pattern ◽  
N Limitation ◽  
The Past ◽  
Global Trend ◽  
Green Vegetation ◽  
Leaf Level ◽  
New Perspective ◽  
N Demand

&lt;div&gt; &lt;p&gt;Nitrogen (N) limitation constrains the magnitude of terrestrial carbon uptake in response to CO&lt;sub&gt;2&amp;#160;&lt;/sub&gt;fertilization and climate change. However, the trajectory of N demand, and how it is influenced by continuing changes in CO&lt;sub&gt;2&amp;#160;&lt;/sub&gt;and climate, is incompletely understood. We estimate recent changes in global canopy N demand based on a well-tested optimality hypothesis for the control of photosynthetic capacity (&lt;em&gt;V&lt;/em&gt;&lt;sub&gt;cmax&lt;/sub&gt;). The predicted global pattern of optimal leaf-level &lt;em&gt;V&lt;/em&gt;&lt;sub&gt;cmax&amp;#160;&lt;/sub&gt;is similar to the pattern derived from remotely sensed chlorophyll retrievals. Over the period from 1982 to 2015, rising CO&lt;sub&gt;2&amp;#173; &lt;/sub&gt;and warming both contributed to decreasing leaf-level N demand. Widespread increases in green vegetation cover over the same period (especially in high latitudes) imply increasing total canopy N demand. The net global trend is, nonetheless, a decrease in total canopy N demand. This work provides a new perspective on the past, present and future of the global terrestrial N cycle.&lt;/p&gt; &lt;/div&gt;

scholarly journals Genome-Wide Differential DNA Methylation and miRNA Expression Profiling Reveals Epigenetic Regulatory Mechanisms Underlying Nitrogen-Limitation-Triggered Adaptation and Use Efficiency Enhancement in Allotetraploid Rapeseed

2020 ◽  
Vol 21 (22) ◽  
pp. 8453
Author(s):  
Ying-peng Hua ◽  
Ting Zhou ◽  
Jin-yong Huang ◽  
Cai-peng Yue ◽  
Hai-xing Song ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Epigenetic Modification ◽  
Lateral Roots ◽  
Regulatory Mechanisms ◽  
Crop Species ◽  
N Limitation ◽  
Genome Wide ◽  
Differentially Methylated Genes ◽  
N Metabolism ◽  
Use Efficiency

Improving crop nitrogen (N) limitation adaptation (NLA) is a core approach to enhance N use efficiency (NUE) and reduce N fertilizer application. Rapeseed has a high demand for N nutrients for optimal plant growth and seed production, but it exhibits low NUE. Epigenetic modification, such as DNA methylation and modification from small RNAs, is key to plant adaptive responses to various stresses. However, epigenetic regulatory mechanisms underlying NLA and NUE remain elusive in allotetraploid B. napus. In this study, we identified overaccumulated carbohydrate, and improved primary and lateral roots in rapeseed plants under N limitation, which resulted in decreased plant nitrate concentrations, enhanced root-to-shoot N translocation, and increased NUE. Transcriptomics and RT-qPCR assays revealed that N limitation induced the expression of NRT1.1, NRT1.5, NRT1.7, NRT2.1/NAR2.1, and Gln1;1, and repressed the transcriptional levels of CLCa, NRT1.8, and NIA1. High-resolution whole genome bisulfite sequencing characterized 5094 differentially methylated genes involving ubiquitin-mediated proteolysis, N recycling, and phytohormone metabolism under N limitation. Hypermethylation/hypomethylation in promoter regions or gene bodies of some key N-metabolism genes might be involved in their transcriptional regulation by N limitation. Genome-wide miRNA sequencing identified 224 N limitation-responsive differentially expressed miRNAs regulating leaf development, amino acid metabolism, and plant hormone signal transduction. Furthermore, degradome sequencing and RT-qPCR assays revealed the miR827-NLA pathway regulating limited N-induced leaf senescence as well as the miR171-SCL6 and miR160-ARF17 pathways regulating root growth under N deficiency. Our study provides a comprehensive insight into the epigenetic regulatory mechanisms underlying rapeseed NLA, and it will be helpful for genetic engineering of NUE in crop species through epigenetic modification of some N metabolism-associated genes.

Shifting stream planform state decreases stream productivity yet increases riparian animal production

Oecologia ◽  
2018 ◽  
Vol 187 (1) ◽  
pp. 167-180 ◽  
Author(s):  
Michael P. Venarsky ◽  
David M. Walters ◽  
Robert O. Hall ◽  
Bridget Livers ◽  
Ellen Wohl
Keyword(s):  
Animal Production ◽  
Stream Productivity

Nutrient-related selection mechanisms in marine phytoplankton communities and the impact of eutrophication on the planktonic food web

1995 ◽  
Vol 32 (4) ◽  
pp. 63-75 ◽  
Author(s):  
R. Riegman
Keyword(s):  
Algal Blooms ◽  
Algal Biomass ◽  
Resource Competition ◽  
Water Quality Management ◽  
Algal Species ◽  
Marine Phytoplankton ◽  
Commercial Fish ◽  
N Limitation ◽  
Phytoplankton Communities ◽  
The Impact

A general increase in nutrient discharges during the last few decades has caused various changes in the algal community structure along the European continental coast. Coincidentally and maybe consequently, the foodweb structure and functioning has altered in local areas causing various phenomena like oxygen depletion, mortality of groups of organisms, foam on beaches, and an increase in the productivity of benthic communities and some commercial fish species. The observed increases in algal biomass and shifts in species composition are discussed in relation to the involved key mechanisms: resource competition and selective grazing. Along the Dutch coastal zone of the North Sea eutrophication has caused a doubling of the yearly averaged algal biomass during the past three decades. The sudden appearance of Phaeocystis summer blooms coincided with a shift from P-limitation towards N-limitation in the Dutch coastal area due to a stronger increase in P-discharge relative to the increase in N-discharge. Competition experiments in continuous cultures showed Phaeocystis to become dominant under N-limitation. Additionally, the large Phaeocystis colonies, which can reach a diameter up to one centimetre, escape from microzooplankton grazing. A computer model is presented which demonstrates a shift from bottom-up towards top-down control if the pelagic environment becomes eutrophicated. Implementation of this concept in a size-differential phytoplankton control model generates the prediction that algal blooms are dominated by species that escape from grazing by those zooplankton species which have a high potential numerical response. In marine environments these are microzooplankton species. These organisms mainly feed on cyanobacteria, prochlorophytes and some nano-algal species. One of the consequences for foodweb structure and the carbon fluxes in marine foodwebs is that eutrophication will lead to the dominance of poorly edible algal species. Eutrophication favours the downward transport of carbon and nutrients towards the sediments not only due to higher algal biomasses but also as a consequence of a shift towards larger algal species with higher sedimentation characteristics. An example is given how these new insights can be used for water quality management purposes.

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