Carbon Dioxide and the Regulation of Photosynthesis: Activities of Photosynthetic Enzymes and Carbonate Dehydratase (Carbonic Anhydrase) in Chlorella after Growth or Adaption in Different Carbon Dioxide Concentrations

1977 ◽  
Vol 4 (1) ◽  
pp. 87 ◽  
Author(s):  
M.L Reed ◽  
D Graham
Keyword(s):  
Carbon Dioxide ◽  
Carbonic Anhydrase ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Chlorella Pyrenoidosa ◽  
Pentose Phosphate ◽  
Fructose Bisphosphate ◽  
Carbon Dioxide Concentrations ◽  
Ribulosebisphosphate Carboxylase ◽  
High Concentrations ◽  
Fraction I

The unicellular green alga Chlorella pyrenoidosa, after growth in air or 5 % (v/v) CO*2, has markedly differing rates of photosynthesis in the presence of very low concentrations of CO*2. It was proposed that the differences could be accounted for by differences in the activities of ribulosebisphosphate carboxylase or other enzymes of the reductive pentose phosphate pathway. This hypothesis was tested and it was shown that between the two types of cells there were no significant differences in the activities of ribulosebisphosphate carboxylase (EC 4.1.1.39), phosphoenolpyruvate carboxylase (EC 4.1.1.31), phosphoenolpyruvate carboxykinase (ATP) (EC 4.1.1.49), glyceraldehyde-phosphate dehydrogenase (NADP) (EC 1.2.1.9), hexosebisphosphatase (EC 3.1.3.11), fructose-bisphosphate aldolase (EC 4.1.2.13), ribosephosphate isomerase (EC 5.3.1.6) and phosphoribulokinase (EC 2.7.1.19). There was also no difference between air-grown and 5% CO*2-grown cells in the content of fraction I protein isolated by disc gel electrophoresis and measured by a colorimetric procedure. A fivefold or sixfold increase in rate of photosynthesis occurs during about 90 min when 5% CO*2-grown Chlorella is illuminated in the presence of a very low CO*2 concentration (approximately 1 �M free CO*2, which is about one-tenth the concentration of CO*2 in distilled water in equilibrium with air). During this increase, the only photosynthetic enzyme to change in activity was carbonate dehydratase (carbonic anhydrase, EC 4.2.1.1). This enzyme was absent from cells grown with 5% CO*2 but was present in air-grown cells. The enzyme appears to be induced by low CO*2 concentrations and repressed by high concentrations. It was concluded that carbonate dehydratase plays a major regulatory role in photosynthesis in Chlorella at low CO*2 concentrations.

THE ESTABLISHMENT OF CARBON DIOXIDE CONCENTRATION GRADIENTS IN ONTARIO WOODLANDS

1966 ◽  
Vol 44 (3) ◽  
pp. 321-329 ◽  
Author(s):  
J. H. Sparling ◽  
M. Alt
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Concentration ◽  
Gas Analyzer ◽  
Concentration Gradients ◽  
Carbon Dioxide Concentrations ◽  
High Concentrations ◽  
Infrared Gas Analyzer

Carbon dioxide concentrations were measured in a number of Ontario woodlands with an infrared gas analyzer. Little evidence of season variation in the concentration of carbon dioxide was obtained. Measurements over 24-hour periods revealed the existence of high concentrations, frequently exceeding 500 p.p.m. at night during midsummer. The high concentrations dropped rapidly at sunrise.The existence of extreme stratification of carbon dioxide which had been reported by earlier workers was not confirmed.

Metabolism of [14C]glucose by postimplantation mouse embryos in vitro

Development ◽  
1983 ◽  
Vol 74 (1) ◽  
pp. 133-142 ◽  
Author(s):  
J. R. Clough ◽  
D. G. Whittingham
Keyword(s):  
Carbon Dioxide ◽  
Lactate Production ◽  
Inhibitory Effect ◽  
Defined Medium ◽  
Pentose Phosphate ◽  
Mouse Embryos ◽  
Co2 Production ◽  
Discernible Effect ◽  
High Concentrations

Carbon dioxide and lactate production from [14C]glucose were measured for post-implantation mouse embryos aged 6 to 9½ days post coitum in static cultures with a defined medium. The rate of metabolism increased rapidly and paralleled the increase in protein content indicating a fairly uniform rate of metabolism throughout the period. At all stages studied more than 90% of the glucose utilized was converted to lactate. Over a quarter of carbon dioxide produced was derived from the C-1 position resulting in high C-1: C-6 ratios, indicating that the Pentose Phosphate Shunt is a major oxidative pathway. The influence of various culture condition on CO2 production showed that high concentrations of glucose did not affect glucose utilization whilst high lactate concentrations had a significant inhibitory effect. Pyruvate had no discernible effect.

scholarly journals Properties of pyruvate kinase and phosphoenolpyruvate carboxykinase in relation to the direction and regulation of phosphoenolpyruvate metabolism in muscles of the frog and marine invertebrates

1978 ◽  
Vol 174 (3) ◽  
pp. 979-987 ◽  
Author(s):  
Victor A. Zammit ◽  
Eric A. Newsholme
Keyword(s):  
Pyruvate Kinase ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Marine Invertebrates ◽  
Adductor Muscle ◽  
Sea Anemone ◽  
Anaerobic Conditions ◽  
Fructose Bisphosphate ◽  
Low Concentrations ◽  
Optimum Ph ◽  
Hill Coefficients

1. The properties of pyruvate kinase and, if present, phosphoenolpyruvate carboxykinase from the muscles of the sea anemone, scallop, oyster, crab, lobster and frog were investigated. 2. In general, the properties of pyruvate kinase from all muscles were similar, except for those of the enzyme from the oyster (adductor muscle); the pH optima were between 7.1 and 7.4, whereas that for oyster was 8.2; fructose bisphosphate lowered the optimum pH of the oyster enzyme from 8.2 to 7.1, but it had no effect on the enzymes from other muscles. Hill coefficients for the effect of the concentration of phosphoenolpyruvate were close to unity in the absence of added alanine for the enzymes from all muscles except oyster adductor muscle; it was 1.5 for this enzyme. Alanine inhibited the enzyme from all muscles except the frog; this inhibition was relieved by fructose bisphosphate. Low concentrations of alanine were very effective with the enzyme from the oyster (50% inhibition was observed at 0.4mm). Fructose bisphosphate activated the enzyme from all muscles, but extremely low concentrations were effective with the oyster enzyme (0.13μm produced 50% activation). 3. In general, the properties of phosphoenolpyruvate carboxykinase from the sea anemone and oyster muscles are similar: the Km values for phosphoenolpyruvate are low (0.10 and 0.13mm); the enzymes require Mn2+ in addition to Mg2+ for activity; and ITP inhibits the enzymes and the inhibition is relieved by alanine. These latter compounds had no effect on enzymes from other muscles. 4. It is suggested that changes in concentrations of fructose bisphosphate, alanine and ITP produce a coordinated mechanism of control of the activities of pyruvate kinase and phosphoenolpyruvate carboxykinase in the sea anemone and oyster muscles, which ensures that phosphoenolpyruvate is converted into oxaloacetate and then into succinate in these muscles under anaerobic conditions. 5. It is suggested that in the muscles of the crab, lobster and frog, phosphoenolpyruvate carboxykinase catalyses the conversion of oxaloacetate into phosphoenolpyruvate. This may be part of a pathway for the oxidation of some amino acids in these muscles.

scholarly journals Snowfall-albedo feedbacks could have led to deglaciation of snowball Earth starting from mid-latitudes

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Philipp de Vrese ◽  
Tobias Stacke ◽  
Jeremy Caves Rugenstein ◽  
Jason Goodman ◽  
Victor Brovkin
Keyword(s):  
Carbon Dioxide ◽  
Atmospheric Carbon Dioxide ◽  
Climate Models ◽  
Hydrological Cycle ◽  
High Surface ◽  
Dust Deposition ◽  
Carbon Dioxide Concentrations ◽  
Maximum Temperatures ◽  
Carbon Dioxide Levels ◽  
Earth’S Climate

AbstractSimple and complex climate models suggest a hard snowball – a completely ice-covered planet – is one of the steady-states of Earth’s climate. However, a seemingly insurmountable challenge to the hard-snowball hypothesis lies in the difficulty in explaining how the planet could have exited the glaciated state within a realistic range of atmospheric carbon dioxide concentrations. Here, we use simulations with the Earth system model MPI-ESM to demonstrate that terminal deglaciation could have been triggered by high dust deposition fluxes. In these simulations, deglaciation is not initiated in the tropics, where a strong hydrological cycle constantly regenerates fresh snow at the surface, which limits the dust accumulation and snow aging, resulting in a high surface albedo. Instead, comparatively low precipitation rates in the mid-latitudes in combination with high maximum temperatures facilitate lower albedos and snow dynamics that – for extreme dust fluxes – trigger deglaciation even at present-day carbon dioxide levels.

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