Photosynthetic carbon metabolism of isolated spinach mesophyll cells was characterized under conditions favoring photorespiratory (PR; 0.04% CO(2) and 20% O(2)) and nonphotorespiratory (NPR; 0.2% CO(2) and 2% O(2)) metabolism, as well as intermediate conditions. Comparisons were made between the metabolic effects of extracellularly supplied NH(4) (+) and intracellular NH(4) (+), produced primar...

Carbox dioxide fixation studies were conducted with rapidly growing JA-1 sarcoma cells in vitro. Isotope was isolated in asparagine, aspartic acid, glutamic acid, and glutamine. Chemical degradation of these compounds suggested three sites of fixation. They were carbon dioxide condensation with (a) pyruvic acid, (6) propionyl CoA, and (c) a three-carbon fragment such as the isopropyl carbons of...

Carbox dioxide fixation studies were conducted with rapidly growing JA-1 sarcoma cells in vitro. Isotope was isolated in asparagine, aspartic acid, glutamic acid, and glutamine. Chemical degradation of these compounds suggested three sites of fixation. They were carbon dioxide condensation with (a) pyruvic acid, (6) propionyl CoA, and (c) a three-carbon fragment such as the isopropyl carbons of...

Several lines of evidence indicate that biotin is involved in the biological fixation of carbon dioxide. Lardy, Potter, and Elvehjem (1) have demonstrated that the biotin requirement of Lactobacillus arabinosus is partially replaceable by oxalacetate and that the growth stimulation of this organism by carbon dioxide is evident only when biotin is present. From microbiological studies with antim...

Because the nature of the main resource that limits bacterioplankton (e.g. organic carbon [C] or phosphorus [P]) has biogeochemical implications concerning organic C accumulation in freshwater ecosystems, empirical knowledge is needed concerning how bacteria respond to these two resources, available alone or together. We performed field experiments of resource manipulation (2×2 factorial design...

The succulent Kalanchoe blossfeldiana v. Poel. var Tom Thumb was treated on long and short photoperiods for 6 weeks during which short day plants developed thicker leaves, flowered prolifically, and exhibited extensive net dark fixation of carbon dioxide. In contrast, long day plants remained vegetative and did not develop thicker leaves or exhibit net carbon dioxide dark fixation. When examine...

In vitro studies of dark (14)CO(2) fixation with isolated cell aggregates of Kalanchoë fedtschenkoi showed that malate synthesized after 20 sec is predominantly (85 to 92%) labeled at carbon 4, while after 20 min only 65 to 69% of the radioactivity was located in this position. The intramolecular labeling pattern of malate could not be changed by supplementing the cells with carboxylation react...

Phytoplankton have a crucial role in the conversion of greenhouse gas sources and sinks natural water bodies, such as lakes, rivers, oceans. In response to environmental changes, phytoplankton adapt by altering their carbon utilization strategies, which affect fixation rates fluxes at water–air interface. This paper classifies summarizes main strategies terms acquisition, metabolism, emission. ...

1. BARTLEY, WV. and DAVIEs, R. E. Active transport of ions by subcellular particles. Biochem. Jour. 57: 37-49. 1954. 2. BULEN, W. A., VARNER, J. E. and BURRELL, R. C. Separation of organic acids from plant tissues. Anal. Chem. 24: 187-190. 1952. 3. GRAHAM, J. S. D. and YOUNG, L. C. T. Fixation of carbon dioxide in particulate preparations from barley roots. Plant Physiol. 34: 520-526. 1959. 4. ...

Thermodynamics impose a major constraint on the structure of metabolic pathways. Here, we use carbon fixation pathways to demonstrate how thermodynamics shape the structure of pathways and determine the cellular resources they consume. We analyze the energetic profile of prototypical reactions and show that each reaction type displays a characteristic change in Gibbs energy. Specifically, altho...