The role of transmembrane solute flux in regulation of CO2 fixation in chloroplasts

1983 ◽  
Vol 11 (1) ◽  
pp. 74-76 ◽  
Author(s):  
R. C. LEEGOOD ◽  
D. A. WALKER
Keyword(s):  
Co2 Fixation ◽  
Solute Flux

The role of temperate trees and forests in CO2 fixation

Vegetatio ◽  
1995 ◽  
Vol 121 (1-2) ◽  
pp. 157-174 ◽  
Author(s):  
Paul G. Jarvis
Keyword(s):  
Co2 Fixation ◽  
Temperate Trees

The role of temperature in the regulation of the circadian rhythm of CO2 fixation in Bryophyllum fedtschenkoi

Planta ◽  
1995 ◽  
Vol 196 (2) ◽  
Author(s):  
PamelaJ. Carter ◽  
MalcolmB. Wilkins ◽  
HughG. Nimmo ◽  
CharlesA. Fewson
Keyword(s):  
Circadian Rhythm ◽  
Co2 Fixation

Phloem water relations and root growth

2000 ◽  
Vol 27 (6) ◽  
pp. 539 ◽  
Author(s):  
Jeremy Pritchard ◽  
Sam Winch ◽  
Nick Gould
Keyword(s):  
Cell Expansion ◽  
Control Point ◽  
Turgor Pressure ◽  
Significant Proportion ◽  
Physiological Data ◽  
Solute Flux ◽  
Root Cells ◽  
Cell Turgor ◽  
The Relationship

In this paper the biophysical basis of cell expansion is described, paying particular attention to the waterrelations that underpin the process. The connection of growing root cells to the rest of the plant will be addressed and possible control points in the hardware identified. Examples of environmental modification of root extension, and therefore water and solute import, are given, and the relationship with current accepted theories of solute translocation discussed. The opportunities for delivery of solutes and water to be regulated by the growing root itself will be considered, in particular the dual role of cell wall loosening in decreasing both sink cell turgor and water potential. We conclude that a significant proportion of the water for cell expansion can enter growing root cells through the phloem. The physiological data presented rule out alterations in the turgor pressure difference between sieve element and cell as a modulator of solute flux. The plasmodesmata are identified as the major control point of solute flux along the symplastic pathway.

scholarly journals Thioester synthesis through geoelectrochemical CO2 fixation on Ni sulfides

2020 ◽  
Author(s):  
Norio Kitadai ◽  
Ryuhei Nakamura ◽  
Masahiro Yamamoto ◽  
Satoshi Okada ◽  
Wataru Takahagi ◽  
...  
Keyword(s):  
Origin Of Life ◽  
Room Temperature ◽  
Nickel Sulfide ◽  
Co2 Fixation ◽  
Hydrothermal Systems ◽  
Co Dehydrogenase ◽  
Enzymatic Process ◽  
Electrochemical Condition ◽  
Co2 Electroreduction

Abstract Thioester synthesis by CO dehydrogenase/acetyl-CoA synthase is among the most ancient autotrophic metabolisms. Although the preceding prebiotic CO2 fixation routes to thioesters are often suggested, none has any experimentally supported evidence. Here we demonstrate that, under an electrochemical condition realizable in early ocean hydrothermal systems, nickel sulfide (NiS) gradually reduces to Ni0, while accumulating surface-bound CO due to CO2 electroreduction. The resultant partially reduced NiS facilitates thioester (S-methyl thioacetate) formation from CO and methanethiol even at room temperature and neutral pH. This thioester formation can further be enhanced up to a selectivity of 56% by NiS coprecipitating with FeS or CoS. Considering the central role of Ni in the enzymatic process mentioned above, our demonstrated thioester synthesis with the partially reduced NiS could have a direct implication to the autotrophic origin of life.

scholarly journals Thioester Synthesis through Geoelectrochemical CO2 Fixation on Ni Sulfides

2020 ◽  
Author(s):  
Norio Kitadai ◽  
Ryuhei Nakamura ◽  
Masahiro Yamamoto ◽  
Satoshi Okada ◽  
Wataru Takahagi ◽  
...  
Keyword(s):  
Origin Of Life ◽  
Room Temperature ◽  
Nickel Sulfide ◽  
Co2 Fixation ◽  
Hydrothermal Systems ◽  
Co Dehydrogenase ◽  
Enzymatic Process ◽  
Electrochemical Condition ◽  
Co2 Electroreduction

Thioester synthesis by CO dehydrogenase/acetyl-CoA synthase is among the most ancient autotrophic metabolisms. Although the preceding prebiotic CO2 fixation routes to thioesters are often suggested, none has any experimentally supported evidence. Here we demonstrate that, under an electrochemical condition realizable in early ocean hydrothermal systems, nickel sulfide (NiS) gradually reduces to Ni0, while accumulating surface-bound CO due to CO2 electroreduction. The resultant partially reduced NiS facilitates thioester (S-methyl thioacetate) formation from CO and methanethiol even at room temperature and neutral pH. This thioester formation can further be enhanced up to a selectivity of 56% by NiS coprecipitating with FeS or CoS. Considering the central role of Ni in the enzymatic process mentioned above, our demonstrated thioester synthesis with the partially reduced NiS could have a direct implication to the autotrophic origin of life.<br>

scholarly journals Release and fixation of CO2 by guinea-pig kidney tubules metabolizing aspartate

1992 ◽  
Vol 284 (3) ◽  
pp. 697-703
Author(s):  
G Martin ◽  
C Michoudet ◽  
N Vincent ◽  
G Baverel
Keyword(s):  
Guinea Pig ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Co2 Fixation ◽  
Carbon Oxidation ◽  
Kidney Tubules ◽  
Pig Kidney ◽  
Glutamine Synthesis ◽  
Oxoglutarate Dehydrogenase

1. The metabolism of L-[U-14C]aspartate, L-[1-14C]aspartate and L-[4-14C]aspartate was studied in isolated guinea-pig kidney tubules. 2. Oxidation of C-1 plus that of C-4 of aspartate accounted for 90-92% of the CO2 released from aspartate, whereas oxidation of the inner carbon atoms of aspartate (which occurs beyond the 2-oxoglutarate dehydrogenase step) represented only 8-10% of aspartate carbon oxidation. 3. The formation of [1-14C]glutamine and [1-14C]glutamate from [1-14C]aspartate and [4-14C]aspartate indicated that about one-third of the oxaloacetate synthesized from aspartate underwent randomization at the level of fumarate. 4. With [U-14C]aspartate as substrate, the percentage of the C-1 of glutamate and glutamine found radiolabelled after 60 min of incubation was 92.7% and 47.5% in the absence and the presence of bicarbonate respectively. 5. That CO2 fixation occurred at high rates in the presence of bicarbonate was demonstrated by incubating tubules with aspartate plus [14C]bicarbonate; under this condition, the label fixed was found in C-1 of glutamate, glutamine and aspartate, as well as in C-4 of aspartate, demonstrating not only randomization of aspartate carbon but also aspartate resynthesis secondary to oxaloacetate cycling via phosphoenolpyruvate carboxykinase, pyruvate kinase and pyruvate carboxylase. 6. The importance of CO2 fixation in glutamine synthesis from aspartate is discussed in relation to the possible role of the guinea-pig kidney in systemic acid-base regulation in vivo.

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