A culture system enabling in situ determination of net and gross photosynthesis, O2 evolution, N assimilation, and C2H2 reduction in cyanobacteria

1985 ◽  
Vol 63 (6) ◽  
pp. 1025-1030 ◽  
Author(s):  
David H. Turpin ◽  
David B. Layzell
Keyword(s):  
Steady State ◽  
Culture System ◽  
Gas Analysis ◽  
O2 Evolution ◽  
Chlorophyll Contents ◽  
Gross Photosynthesis ◽  
Carbon And Nitrogen ◽  
N Assimilation ◽  
C Assimilation

A chemostat culture system is described in which measurements of rates associated with carbon and nitrogen assimilation may be made in in situ steady-state cultures of N2-fixing cyanobacteria. Net C and N assimilations were determined from the steady-state cellular carbon and nitrogen contents and the steady-state growth rate of the cultures. O2 evolution in the light and short-term 14C assimilation were measured simultaneously in unperturbed culture cuvettes. 14C assimilation was linear with time through the origin over the 20-min sampling period, thereby providing a measure of gross photosynthesis. C2H2 reduction was measured within the culture cuvette using an open gas analysis system. Steady-state rates of C2H2 reduction were obtained within 10 min and remained constant for up to 1 h. Preliminary results showed that at similar growth rates (0.018–0.019 h−1) cultures grown on [Formula: see text] and N2 contained heterocysts, were smaller, and had higher chlorophyll contents than cells grown on NH3. Corresponding gross photosynthesis was 1.6 to 1.8 times higher than net photosynthesis in [Formula: see text] and N2-grown cells; however, for NH3-grown cells the ratio of gross photosynthesis:net photosynthesis was close to unity. These results are discussed with reference to the energetic costs associated with N assimilation in cyanobacteria.

scholarly journals Measuring and modelling the isotopic composition of soil respiration: insights from a grassland tracer experiment

2011 ◽  
Vol 8 (5) ◽  
pp. 1333-1350 ◽  
Author(s):  
U. Gamnitzer ◽  
A. B. Moyes ◽  
D. R. Bowling ◽  
H. Schnyder
Keyword(s):  
Steady State ◽  
Isotopic Composition ◽  
Transport Model ◽  
Tracer Experiment ◽  
Atmospheric Co2 ◽  
Soil Co2 ◽  
Soil Air ◽  
Co2 Transport ◽  
Atmosphere System

Abstract. The carbon isotopic composition (δ13C) of CO2 efflux (δ13Cefflux) from soil is generally interpreted to represent the actual isotopic composition of the respiratory source (δ13CRs). However, soils contain a large CO2 pool in air-filled pores. This pool receives CO2 from belowground respiration and exchanges CO2 with the atmosphere (via diffusion and advection) and the soil liquid phase (via dissolution). Natural or artificial modification of δ13C of atmospheric CO2 (δ13Catm) or δ13CRs causes isotopic disequilibria in the soil-atmosphere system. Such disequilibria generate divergence of δ13Cefflux from δ13CRs (termed "disequilibrium effect"). Here, we use a soil CO2 transport model and data from a 13CO2/12CO2 tracer experiment to quantify the disequilibrium between δ13Cefflux and δ13CRs in ecosystem respiration. The model accounted for diffusion of CO2 in soil air, advection of soil air, dissolution of CO2 in soil water, and belowground and aboveground respiration of both 12CO2 and 13CO2 isotopologues. The tracer data were obtained in a grassland ecosystem exposed to a δ13Catm of −46.9 ‰ during daytime for 2 weeks. Nighttime δ13Cefflux from the ecosystem was estimated with three independent methods: a laboratory-based cuvette system, in-situ steady-state open chambers, and in-situ closed chambers. Earlier work has shown that the δ13Cefflux measurements of the laboratory-based and steady-state systems were consistent, and likely reflected δ13CRs. Conversely, the δ13Cefflux measured using the closed chamber technique differed from these by −11.2 ‰. Most of this disequilibrium effect (9.5 ‰) was predicted by the CO2 transport model. Isotopic disequilibria in the soil-chamber system were introduced by changing δ13Catm in the chamber headspace at the onset of the measurements. When dissolution was excluded, the simulated disequilibrium effect was only 3.6 ‰. Dissolution delayed the isotopic equilibration between soil CO2 and the atmosphere, as the storage capacity for labelled CO2 in water-filled soil pores was 18 times that of soil air. These mechanisms are potentially relevant for many studies of δ13CRs in soils and ecosystems, including FACE experiments and chamber studies in natural conditions. Isotopic disequilibria in the soil-atmosphere system may result from temporal variation in δ13CRs or diurnal changes in the mole fraction and δ13C of atmospheric CO2. Dissolution effects are most important under alkaline conditions.

Active oxygen species in the liver of rats submitted to chronic hypobaric hypoxia

1993 ◽  
Vol 264 (6) ◽  
pp. C1395-C1400 ◽  
Author(s):  
L. E. Costa ◽  
S. Llesuy ◽  
A. Boveris
Keyword(s):  
Steady State ◽  
Singlet Oxygen ◽  
Active Oxygen Species ◽  
Liver Mitochondria ◽  
Active Oxygen ◽  
Female Rats ◽  
H2o2 Production ◽  
Oxygen Species ◽  
State Concentration

The spontaneous in situ liver chemiluminescence of female rats submitted to 4,400 m (simulated altitude) for 2 mo and of their corresponding controls at sea level was determined as an approach to the measurement of the intracellular steady-state concentrations of singlet oxygen and oxygen free radicals. Spontaneous liver chemiluminescence was decreased by approximately 40% in hypoxic rats, whereas CCl4-induced chemiluminescence was unchanged. Liver mitochondria isolated from hypoxic rats showed a 53% decreased rate of H2O2 production and an increased content of cytochrome b (36%), with normal content of cytochromes c1, c, and a-a3. Superoxide dismutase showed a 26% decrease in activity, whereas catalase and glutathione peroxidase activities were not significantly decreased by this extent of hypoxia. Cytochrome P-450 and glutathione contents were unchanged. There were no significant differences in the hydroperoxide-initiated chemiluminescence (an estimation of tissue chain-breaker antioxidants) of homogenates, mitochondria, and microsomes. Results suggest that in chronic hypoxia there is a lower rate of generation of active oxygen species in liver, leading to a decreased steady-state concentration of singlet oxygen.

scholarly journals Assimilation of Particular Organic Matter and Dissolved Organic or Inorganic Compounds by Cribroelphidium selseyense (Foraminifera)

2021 ◽  
Vol 8 ◽  
Author(s):  
Michael Lintner ◽  
Bianca Lintner ◽  
Wolfgang Wanek ◽  
Sarina Schmidt ◽  
Nina Keul ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Isotope Labeling ◽  
Inorganic Compounds ◽  
Algal Species ◽  
Food Sources ◽  
The Baltic Sea ◽  
Carbon And Nitrogen ◽  
Freeze Dried ◽  
N Assimilation ◽  
The Baltic

Marine carbon and nitrogen processing through microorganisms’ metabolism is an important aspect of the global element cycles. For that purpose, we used foraminifera to analyze the element turnover with different algae food sources. In the Baltic Sea, benthic foraminifera are quite common and therefore it is important to understand their metabolism. Especially, Cribroelphidium selseyense, also occurring in the Baltic Sea, has often been used for laboratory feeding experiments to test their effect on carbon or nitrogen turnover. Therefore, foraminifera were collected from the Kiel Fjord and fed with six different algal species in two qualities (freeze-dried algae vs. fresh algae, all 13C- and 15N-labeled). Also, labeled dissolved inorganic C and N compounds and glucose were offered to the foraminifera to test direct assimilation of dissolved compounds (carbon and nitrogen) from the water column. Our experiments showed that after 15 days of incubation, there were highly significant differences in isotope labeling in foraminifera fed with fresh algae and dry algae, depending on algal species. Further, different algal species led to different 13C and 15N enrichment in the studied foraminifera, highlighting a feeding preference for one diatom species and an Eustigmatophyte. A significant carbon assimilation from HCO3– was observed after 7 days of incubation. The N assimilation from NH4+ was significantly higher than for NO3– as an inorganic N source. The uptake of glucose showed a lag phase, which was often observed during past experiments, where foraminifera were in a steady state and showed no food uptake at regular intervals. These results highlight the importance of food quality on the feeding behavior and metabolic pathways for further studies of foraminiferal nutrition and nutrient cycling.

scholarly journals First in situ estimations of small phytoplankton carbon and nitrogen uptake rates in the Kara, Laptev, and East Siberian seas

2018 ◽  
Author(s):  
Bhavya P. Sadanandan ◽  
Jang Han Lee ◽  
Ho Won Lee ◽  
Jae Joong Kaang ◽  
Jae Hyung Lee ◽  
...  
Keyword(s):  
Sea Ice ◽  
Nitrogen Uptake ◽  
N Uptake ◽  
Total Carbon ◽  
The Arctic ◽  
Carbon And Nitrogen ◽  
Uptake Rates ◽  
Wide Range ◽  
Small Phytoplankton

Abstract. Carbon and nitrogen uptake rates by small phytoplankton (0.7–5 μm) in the Kara, Laptev, and East Siberian seas in the Arctic Ocean were quantified using in situ isotope labelling experiments for the first time as part of the NABOS (Nansen and Amundsen Basins Observational System) program during August 21 to September 22, 2013. The depth integrated C, NO3−, and NH4+ uptake rates by small phytoplankton showed a wide range from 0.54 to 15.96 mg C m−2 h−1, 0.05 to 1.02 and 0.11 to 3.73 mg N m−2 h−1, respectively. The contributions of small phytoplankton towards the total C, NO3−, and NH4+ was varied from 24 to 89 %, 32 to 89 %, and 28 to 89 %, respectively. The turnover times for NO3− and NH4+ by small phytoplankton during the present study point towards the longer residence times (years) of the nutrients in the deeper waters, particularly for NO3−. Relatively, higher C and N uptake rates by small phytoplankton obtained during the present study at locations with less sea ice concentrations points towards the possibility of small phytoplankton thrive under sea ice retreat under warming conditions. The high contributions of small phytoplankton towards the total carbon and nitrogen uptake rates suggest capability of small size autotrophs to withstand in the adverse hydrographic conditions introduced by climate change.

Phase Transformation Behavior and Stability of LiNiO 2 Cathode Material for Li‐Ion Batteries Obtained from In Situ Gas Analysis and Operando X‐Ray Diffraction

ChemSusChem ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 2240-2250 ◽  
Author(s):  
Lea de Biasi ◽  
Alexander Schiele ◽  
Maria Roca‐Ayats ◽  
Grecia Garcia ◽  
Torsten Brezesinski ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Cathode Material ◽  
Gas Analysis ◽  
Li Ion Batteries ◽  
X Ray Diffraction ◽  
Transformation Behavior ◽  
X Ray ◽  
Phase Transformation Behavior ◽  
Li Ion
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