Effect of light and CO2 on inorganic carbon uptake in the invasive aquatic CAM-plant Crassula helmsii

2010 ◽  
Vol 37 (8) ◽  
pp. 737 ◽  
Author(s):  
Signe Koch Klavsen ◽  
Stephen C. Maberly
Keyword(s):  
Native Species ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
High Light ◽  
Photosynthetic Rates ◽  
Co2 Compensation Point ◽  
Low Co2 ◽  
Co2 Concentrations ◽  
Invasive Aquatic Plant ◽  
Effect Of Light

Crassula helmsii (T. Kirk) Cockayne is an invasive aquatic plant in Europe that can suppress many native species because it can grow at a large range of dissolved inorganic carbon concentrations and light levels. One reason for its ecological success may be the possession of a regulated Crassulacean Acid Metabolism (CAM), which allows aquatic macrophytes to take up CO2 in the night in addition to the daytime. The effect of light and CO2 on the regulation of CAM and photosynthesis in C. helmsii was investigated to characterise how physiological acclimation may confer this ecological flexibility. After 3 weeks of growth at high light (230 µmol photon m–2 s–1), C. helmsii displayed 2.8 times higher CAM at low compared with high CO2 (22 v. 230 mmol m–3). CAM was absent in plants grown at low light (23 µmol photon m–2 s–1) at both CO2 concentrations. The observed regulation patterns are consistent with CAM acting as a carbon conserving mechanism. For C. helmsii grown at high light and low CO2, mean photosynthetic rates were relatively high at low concentrations of CO2 and were on average 80 and 102 µmol O2 g–1 DW h–1 at CO2 concentrations of 3 and 22 mmol m–3 CO2, which, together with mean final pH values of 9.01 in the pH drift, indicate a low CO2 compensation point (<3 mmol m–3) but do not indicate use of bicarbonate as an additional source of exogenous inorganic carbon. The relatively high photosynthetic rates during the entire daytime were caused by internally derived CAM-CO2 and uptake from the external medium. During decarboxylation, CO2 generated from CAM contributed up to 29% to photosynthesis, whereas over a day the contribution to the carbon balance was ≤13%. The flexible adjustment of CAM and the ability to maintain photosynthesis at very low external CO2 concentrations, partly by making use of internally generated CO2 via CAM, may contribute to the broad ecological niche of C. helmsii.

Photosynthetic utilisation of inorganic carbon and its regulation in the marine diatom Skeletonema costatum

2004 ◽  
Vol 31 (10) ◽  
pp. 1027 ◽  
Author(s):  
Xiongwen Chen ◽  
Kunshan Gao
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Skeletonema Costatum ◽  
Co2 Concentration ◽  
Marine Diatom ◽  
Disulfonic Acid ◽  
High Co2 ◽  
Low Co2 ◽  
Diatom Skeletonema Costatum ◽  
Very High

Photosynthetic uptake of inorganic carbon and regulation of photosynthetic CO2 affinity were investigated in Skeletonema costatum (Grev.) Cleve. The pH independence of K1/2(CO2) values indicated that algae grown at either ambient (12 μmol L–1) or low (3 μmol L–1) CO2 predominantly took up CO2 from the medium. The lower pH compensation point (9.12) and insensitivity of photosynthetic rate to di-isothiocyanatostilbene disulfonic acid (DIDS) indicated that the alga had poor capacity for direct HCO3– utilisation. Photosynthetic CO2 affinity is regulated by the concentration of CO2 rather than HCO3–, CO32– or total dissolved inorganic carbon (DIC) in the medium. The response of photosynthetic CO2 affinity to changes in CO2 concentration was most sensitive within the range 3–48 μmol L–1 CO2. Light was required for the induction of photosynthetic CO2 affinity, but not for its repression, when cells were shifted between high (126 μmol L–1) and ambient (12 μmol L–1) CO2. The time needed for cells grown at high CO2 (126 μmol L–1) to fully develop photosynthetic CO2 affinity at ambient CO2 was approximately 2 h, but acclimation to low or very low CO2 levels (3 and 1.3 μmol L–1, respectively) took more than 10 h. Cells grown at low CO2 (3 μmol L–1) required approximately 10 h for repression of all photosynthetic CO2 affinity when transferred to ambient or high CO2 (12 or 126 μmol L–1, respectively), and more than 10 h at very high CO2 (392 μmol L–1).

Photoinhibition of Respiration in Epilithic Periphyton

1987 ◽  
Vol 44 (S1) ◽  
pp. s150-s153 ◽  
Author(s):  
R. W. Graham ◽  
M. A. Turner
Keyword(s):  
Sulfuric Acid ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Dark Respiration ◽  
Gross Photosynthesis ◽  
Dark Control ◽  
Low Concentrations ◽  
Effect Of Light

To determine whether respiration in the light was equal to respiration in the dark we examined epilithic periphyton from a lake acidified experimentally with sulfuric acid. Because of the low concentrations of dissolved inorganic carbon, we could use both 12C and 14C uptake techniques. Using the 14C technique we could correct for residual photosynthesis in samples treated with the photosynthetic inhibitor DCMU (3-(3,4-dichlorophenyl)-1,1-dsmethyiurea). DCMU did not alter rates of dark respiration. However, respiration of DCMU-treated samples in the light was less than in the dark (P < 0.01). This photoinhibition of respiration was about 40% of dark control values. If we had calculated gross photosynthesis for the specific conditions of this experiment, but assumed incorrectly that light and dark respiration were equal, we would have overestimated gross photosynthesis by about 30%. Thus, if the ratio of respiration to photosynthesis is high, researchers will have to evaluate the effect of light on respiration to better estimate gross photosynthesis. The technique we describe, of monitoring both 12C and 14C flux in DCMU-treated samples in the light, will provide an underestimate of respiration in the light.

Variability in the benefits of ocean acidification to photosynthetic rates of macroalgae without CO2-concentrating mechanisms

2020 ◽  
Vol 71 (3) ◽  
pp. 275 ◽  
Author(s):  
C. E. Cornwall ◽  
C. L. Hurd
Keyword(s):  
Ocean Acidification ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Surface Seawater ◽  
Seaweed Species ◽  
Photosynthetic Rates ◽  
Uptake Rates ◽  
Carbon Dioxide Co2 ◽  
Co2 Concentrating Mechanisms ◽  
Emissions Scenario

Increasing concentrations of surface-seawater carbon dioxide (CO2) (ocean acidification) could favour seaweed species that currently are limited for dissolved inorganic carbon (DIC). Among them, those that are unable to use CO2-concentrating mechanisms (CCMs) to actively uptake bicarbonate (HCO3–) across the plasmalemma are most likely to benefit. Here, we assess how the DIC uptake and photosynthetic rates of three rhodophytes without CCMs respond to four seawater CO2 concentrations representing pre-industrial (280μatm), present-day (400μatm), representative concentration pathway (RCP) emissions scenario 8.52050 (650μatm) and RCP 8.52100 (1000μatm). We demonstrated that the photosynthetic rates of only one species increase between the preindustrial and end-of-century scenarios, but because of differing photosynthetic quotients (DIC taken up relative to O2 evolved), all three increase their DIC uptake rates from pre-industrial or present-day scenarios to the end-of-century scenario. These variable, but generally beneficial, responses highlight that not all species without CCMs will respond to ocean acidification uniformly. This supports past assessments that, on average, this group will likely benefit from the impacts of ocean acidification. However, more concerted efforts are now required to assess whether similar benefits to photosynthetic rates and DIC uptake are also observed in chlorophytes and ochrophytes without CCMs.

scholarly journals Ubiquity and functional uniformity in CO2 concentrating mechanisms in multiple phyla of Bacteria is suggested by a diversity and prevalence of genes encoding candidate dissolved inorganic carbon transporters

2020 ◽  
Vol 367 (13) ◽  
Author(s):  
Kathleen M Scott ◽  
Tara L Harmer ◽  
Bradford J Gemmell ◽  
Andrew M Kramer ◽  
Markus Sutter ◽  
...  
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Extreme Environments ◽  
Bacterial Genomes ◽  
Low Co2 ◽  
Transporter Family ◽  
Genes Encoding ◽  
Co2 Concentrating Mechanisms ◽  
Biological Component ◽  
Global Carbon

ABSTRACT Autotrophic microorganisms catalyze the entry of dissolved inorganic carbon (DIC; = CO2 + HCO3− + CO32−) into the biological component of the global carbon cycle, despite dramatic differences in DIC abundance and composition in their sometimes extreme environments. “Cyanobacteria” are known to have CO2 concentrating mechanisms (CCMs) to facilitate growth under low CO2 conditions. These CCMs consist of carboxysomes, containing enzymes ribulose 1,5-bisphosphate oxygenase and carbonic anhydrase, partnered to DIC transporters. CCMs and their DIC transporters have been studied in a handful of other prokaryotes, but it was not known how common CCMs were beyond “Cyanobacteria”. Since it had previously been noted that genes encoding potential transporters were found neighboring carboxysome loci, α-carboxysome loci were gathered from bacterial genomes, and potential transporter genes neighboring these loci are described here. Members of transporter families whose members all transport DIC (CHC, MDT and Sbt) were common in these neighborhoods, as were members of the SulP transporter family, many of which transport DIC. 109 of 115 taxa with carboxysome loci have some form of DIC transporter encoded in their genomes, suggesting that CCMs consisting of carboxysomes and DIC transporters are widespread not only among “Cyanobacteria”, but also among members of “Proteobacteria” and “Actinobacteria”.

Oxygen photoreduction and its effect on CO2 accumulation and assimilation in air-grown cells of Synechococcus UTEX 625

1997 ◽  
Vol 75 (2) ◽  
pp. 274-283 ◽  
Author(s):  
Qinglin Li ◽  
David Thomas Canvin
Keyword(s):  
Light Intensity ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Reducing Power ◽  
High Light Intensity ◽  
High Light ◽  
Anaerobic Conditions ◽  
Key Words Cyanobacteria ◽  
Spectrometric Measurements ◽  
Oxygen Photoreduction

Mass spectrometric measurements of 16O2, 18O2, and 13CO2 were used to measure the rates of gross O2 evolution, O2 uptake, and CO2 assimilation in relation to light intensity, temperature, pH, and O2 concentration by air-grown cells of the cyanobacterium Synechococcus UTEX 625. CO2 fixation and O2 photoreduction increased with increased light intensity and, although CO2 fixation was saturated at 250 μmol ∙ m−2 ∙ s−1, O2 photoreduction was not saturated until about 550 μmol ∙ m−2 ∙ s−1. At high light intensity addition of inorganic carbon to the cells stimulated O2 photoreduction 2-fold when CO2, fixation was allowed and 5-fold when CO2, fixation was inhibited with iodoacetamide. The ability of O2, to act as an acceptor of photosynthetically generated reducing power was dependent upon the O2 concentration, and the substrate concentration required for half maximum rate (K½(O2)) was 53.2 ± 4.2 μM (mean ± SD, n = 3). The Q10 for oxygen photoreduction was about 2. A certain amount (10%) of O2 appeared to be required for maximum photosynthesis, as photosynthesis was inhibited under anaerobic conditions, especially at high light intensity. The point of inhibition is unknown but it seemed unlikely to be on CO2 transport or the concentration of intracellular dissolved inorganic carbon (Ci), as the rate of initial CO2 transport was enhanced and the intracellular Q1 pool increased in size under anaerobic conditions. Key words: cyanobacteria, photosynthesis, Ci concentrating mechanism, inorganic carbon pool, O2 photoreduction, electron transport, temperature.

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