Nitrate uptake in marine phytoplankton: Energy sources and the interaction with carbon fixation

1975 ◽  
Vol 32 (1) ◽  
pp. 77-84 ◽  
Author(s):  
P. G. Falkowski ◽  
D. P. Stone
Keyword(s):  
Nitrate Uptake ◽  
Carbon Fixation ◽  
Marine Phytoplankton ◽  
Energy Sources

scholarly journals Effect of incubation time and substrate concentration on N-uptake rates by phytoplankton in the Bay of Bengal

2005 ◽  
Vol 2 (5) ◽  
pp. 1331-1352
Author(s):  
S. Kumar ◽  
R. Ramesh ◽  
S. Sardesai ◽  
M. S. Sheshshayee
Keyword(s):  
Incubation Time ◽  
Uptake Rate ◽  
Nitrate Uptake ◽  
N Uptake ◽  
Marine Phytoplankton ◽  
Total Production ◽  
New Production ◽  
Urea Uptake ◽  
Uptake Rates

Abstract. We report here the results of three experiments, which are slight variations of the 15N method (JGOFS protocol) for determination of new production. The first two test the effect of (i) duration of incubation time and (ii) concentration of tracer added on the uptake rates of various N-species (nitrate, ammonium and urea) by marine phytoplankton; while the third compares in situ and deck incubations from dawn to dusk. Results indicate that nitrate uptake can be underestimated by experiments where incubation times shorter than 4h or when more than 10% of the ambient concentration of nitrate is added prior to incubation. The f-ratio increases from 0.28 to 0.42 when the incubation time increases from two to four hours. This may be due to the observed increase in the uptake rate of nitrate and decrease in the urea uptake rate. Unlike ammonium [y{=}2.07x{-}0.002\\, (r2=0.55)] and urea uptakes [y{=}1.88x{+}0.004 (r2=0.88)], the nitrate uptake decreases as the concentration of the substrate (x) increases, showing a negative correlation [y{=}-0.76x+0.05 (r2=0.86)], possibly due to production of glutamine, which might suppress nitrate uptake. This leads to decline in the f-ratio from 0.47 to 0.10, when concentration of tracer varies from 0.01 to 0.04μ M. The column integrated total productions are 519 mg C m-2 d-1 and 251 mg C m-2 d-1 for in situ and deck incubations, respectively. The 14C based production at the same location is ~200 mg C m-2 d-1, which is in closer agreement to the 15N based total production measured by deck incubation.

Cycles, Compartments, and Polymerization

2019 ◽  
Author(s):  
David W. Deamer
Keyword(s):  
Genetic Information ◽  
Hydrothermal Vents ◽  
Carbon Fixation ◽  
Energy Sources ◽  
Hydrothermal Conditions ◽  
Biologically Relevant ◽  
Cellular Life ◽  
Primitive Metabolism ◽  
Chain Lengths ◽  
Design Experiments

The two quotes in the epigraph, in juxtaposition, always make me smile, and I tried to keep them in mind while writing this chapter. The first eight chapters of this book have the effect of eliminating the impossible by investigating the facts to which Twain is referring. Perhaps he would consider them trifling, but I doubt that Twain ever performed an experiment to test an idea. Every working scientist knows that science is not just a set of facts but is also a set of questions. The best way to begin answering a question is to pose a hypothesis and that hypothesis begins as a conjecture. Only when we have a hypothesis, can we design experiments to test it, and if we are lucky, the results of those experiments lead us a little closer to the truth. This chapter summarizes facts that lead to an alternative scenario for life’s origin in freshwater hydrothermal conditions rather than a marine origin in saltwater hydrothermal vents. As stated in the introduction to this book, when assumptions are part of the story they will be made explicit so that the logic that arises from them will be clear. What follows in this overview is a list of ten prerequisites we assume are necessary for cellular life to begin, followed by eight assumptions underlying the scenario to be presented here. Prerequisite conditions for life to begin: Dilute solutions of potential reactants are available, together with a process by which they can be sufficiently concentrated to react. Energy sources available in the environment can drive reactions such as carbon fixation, primitive metabolism, and polymerization. Products of reactions accumulate within the site rather than dispersing into the bulk phase environment. Amphiphiles assemble into membranous compartments over the range of temperatures, salt concentrations, and pH values related to each site. Biologically relevant polymers are synthesized with chain lengths sufficient to act as catalysts or incorporate genetic information. A plausible physical mechanism can produce encapsulated polymers as protocells then subject them to combinatorial selection. Organic solutes in aqueous solutions become biochemical solutes within protocells and then substrates supporting a primitive metabolism.

Response of marine phytoplankton to nitrogen deficiency: Decreased nitrate uptake vs enhanced ammonium uptake

1982 ◽  
Vol 70 (1) ◽  
pp. 13-19 ◽  
Author(s):  
Q. Dortch ◽  
J. R. Clayton ◽  
S. S. Thoreson ◽  
S. L. Bressler ◽  
S. I. Ahmed
Keyword(s):  
Nitrate Uptake ◽  
Nitrogen Deficiency ◽  
Marine Phytoplankton ◽  
Ammonium Uptake

scholarly journals Ultra-trace determination of domoic acid in the Ebro Delta estuary by SPE-HILIC-HRMS

2020 ◽  
Vol 12 (15) ◽  
pp. 1966-1974
Author(s):  
Cristina Bosch-Orea ◽  
Josep Sanchís ◽  
Damiá Barceló ◽  
Marinella Farré
Keyword(s):  
Food Web ◽  
Domoic Acid ◽  
Carbon Fixation ◽  
Marine Phytoplankton ◽  
Trace Determination ◽  
Considerable Part ◽  
Marine Food Web ◽  
Marine Food ◽  
Ultra Trace

Marine phytoplankton, such as diatoms, are responsible for a considerable part of carbon fixation and form the basis of the marine food web.

Ultraviolet radiation stimulated activity of extracellular carbonic anhydrase in the marine diatom Skeletonema costatum

2009 ◽  
Vol 36 (2) ◽  
pp. 137 ◽  
Author(s):  
Hongyan Wu ◽  
Kunshan Gao
Keyword(s):  
Carbonic Anhydrase ◽  
Ultraviolet Radiation ◽  
Uv Radiation ◽  
Carbon Fixation ◽  
Skeletonema Costatum ◽  
Marine Phytoplankton ◽  
Marine Diatom ◽  
Redox Activity ◽  
Photosynthetic Carbon Fixation ◽  
Photosynthetic Carbon

Previous studies have shown that reduced levels of solar UV radiation (280–400 nm) can enhance photosynthetic carbon fixation of marine phytoplankton, but the mechanisms are not known. The supply of CO2 for photosynthesis is facilitated by extracellular (periplasmic) carbonic anhydrase (CAe) in most marine phytoplankton species. The present study showed that the CAe activity of Skeletonema costatum (Greville) Cleve was stimulated when treated with UV-A (320–395 nm) or UV-A + UV-B (295–320 nm) in addition to visible radiation. The presence of UV-A and UV-B enhanced the activity by 28% and 24%, respectively, at a low irradiance (PAR 161, UV-A 28, UV-B 0.9 W m−2) and by 21% and 19%, respectively, at a high irradiance (PAR 328, UV-A 58, UV-B 1.9 W m−2) level after exposure for 1 h. Ultraviolet radiation stimulated CAe activity contributed up to 6% of the photosynthetic carbon fixation as a result of the enhanced supply of CO2, as revealed using the CAe inhibitor (acetazolamide). As a result, there was less inhibition of photosynthetic carbon fixation compared with the apparent quantum yield of PSII. The UV radiation stimulated CAe activity coincided with the enhanced redox activity at the plasma membrane in the presence of UV-A and/or UV-B. The present study showed that UV radiation can enhance CAe activity, which plays an important role in counteracting UV inhibition of photosynthesis.

Best Practice in Low-Carbon Community Planning

2012 ◽  
Vol 450-451 ◽  
pp. 1082-1085
Author(s):  
Qiao Ling Luo ◽  
Qing Ming Zhan
Keyword(s):  
Best Practice ◽  
Carbon Fixation ◽  
Renewable Energy Sources ◽  
Green Building ◽  
Community Planning ◽  
Building Design ◽  
Theory And Practice ◽  
Energy Sources ◽  
Low Carbon ◽  
Green Building Design

This paper discusses the theory and practice of low-carbon communities. The paper suggests that the following points should be considered when constructing a low-carbon community: (1) mixed-functions; (2) public transport; (3) carbon fixation through forestry; (4) green building design; (5) water recycling; (6) energy-saving building design and the use of renewable energy sources.

scholarly journals Proteomics of Carbon Fixation Energy Sources in Halothiobacillus neapolitanus

2019 ◽  
Vol 73 ◽  
Author(s):  
Jonathan Hunter ◽  
Maria Marasco ◽  
Ilerioluwa Sowande ◽  
Newton Hilliard
Keyword(s):  
Carbon Fixation ◽  
Energy Sources ◽  
Halothiobacillus Neapolitanus

scholarly journals Physiological and biochemical responses of <i>Emiliania huxleyi</i> to ocean acidification and warming are modulated by UV radiation

2017 ◽  
Author(s):  
Shanying Tong ◽  
David A. Hutchins ◽  
Kunshan Gao
Keyword(s):  
Ocean Acidification ◽  
Uv Radiation ◽  
Carbon Fixation ◽  
Co2 Concentration ◽  
Emiliania Huxleyi ◽  
Marine Phytoplankton ◽  
Negative Effects ◽  
Photosynthetic Carbon Fixation ◽  
Photosynthetic Carbon ◽  
Increasing Temperature

Abstract. Marine phytoplankton such as bloom-forming, calcite-producing coccolithophores, are naturally exposed to solar UV radiation (UVR, 280–400 nm) in the ocean's upper mixed layers. Nevertheless, effects of increasing CO2-induced ocean acidification and warming have rarely been investigated in the presence of UVR. We examined calcification and photosynthetic carbon fixation performance in the most cosmopolitan coccolithophorid, Emiliania huxleyi, grown under high (1000 μatm, HC; pHT: 7.70) and low (400 μatm, LC; pHT: 8.02) CO2 levels, at 15 °C (LT), 20 °C (MT) and 24 °C (HT) with or without UVR. The HC treatment didn't affect photosynthetic carbon fixation at 15 °C, but significantly enhanced it with increasing temperature. Exposure to UVR inhibited photosynthesis, with higher inhibition by UVA (320–395 nm) than UVB (295–320 nm), except in the HC and 24 °C-grown cells, in which UVB caused more inhibition than UVA. Reduced thickness of the coccolith layer in the HC-grown cells appeared to be responsible for the UV-induced inhibition, and an increased repair rate of UVA-derived damage in the HCHT-grown cells could be responsible for lowered UVA-induced inhibition. While calcification was reduced with the elevated CO2 concentration, exposure to UVB or UVA affected it differentially, with the former inhibiting and the latter enhancing it. UVA-induced stimulation of calcification was higher in the HC-grown cells at 15 and 20 °C, whereas at 24 °C, observed enhancement was not significant. The calcification to photosynthesis ratio (Cal / Pho ratio) was lower in the HC treatment, and increasing temperature also lowered the value. However, at 20 and 24 °C, exposures to UVR significantly increased the Cal / Pho ratio, especially in HC-grown cells, by up to 100 %. This implies that UVR can counteract the negative effects of the greenhouse treatment on the Cal / Pho ratio, and so may be a key stressor when considering the impacts of future greenhouse conditions on E. huxleyi.

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