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Potential of arid zone vegetation as a source of substrates

Description: Three aspects of the potential of vegetation in arid zones as a source of substrates are discussed. The first includes the limitations on efficiency of conversion of solar energy to the stored chemical energy of biomass in green plants, and the subsequent biochemical pathways of carbon dioxide fixation and biosynthesis. Second is the potential of plants endogenous to arid zones. Finally, the use of covered agriculture or controlled environmental agriculture (CEA) is considered both in its present form and in terms of possible extenion to the large scale production of stable crops. (JGB)
Date: November 1, 1977
Creator: Bassham, J.A.
Partner: UNT Libraries Government Documents Department


Description: Biosynthesis begins with photosynthesis. Green plants and other photosynthetic organisms use the energy of absorbed visible light to make organic compounds from inorganic compounds. These organic compounds are the starting point for all other biosynthetic pathways. The products of photosynthesis provide not only the substrate material but also chemical energy for all subsequent biosynthesis. For example, nonphotosynthetic organisms making fats from sugars would first break down the sugars to smaller organic molecules. Some of the smaller molecules might be oxidized with O{sub 2} to CO{sub 2} and water. These reactions are accompanied by a release of chemical energy because O{sub 2} and sugar have a high chemical potential energy towards conversion to CO{sub 2} and H{sub 2}O. In a biochemical system only part of this energy would be released as heat. The heat would be used to bring about the conversion of certain enzymic cofactors to their more energetic forms. These cofactors would then enter into specific enzymic reactions in such a way as to supply energy to drive reactions in the direction of fat synthesis. Fats would be formed from the small organic molecules resulting from the breakdown of sugars. Thus sugar, a photosynthetic product, can supply both the energy and the material for the biosynthesis of fats.
Date: October 1, 1960
Creator: Bassham, J.A. & Calvin, Melvin
Partner: UNT Libraries Government Documents Department


Description: The directions for preparing the following acids from labeled acetic acid on a 1 to 20 millimole scale is presented: Succinic acid, malic acid, fumaric acid and tartaric acid. Two methods for preparing the succinic acid are detailed.
Date: June 12, 1951
Creator: Jorgensen, E.C.; Bassham, J.A.; Calvin, M. & Tolbert, B.M.
Partner: UNT Libraries Government Documents Department

Formation of Radioactive Citrulline During PhotosyntheticC14O2-Fixation by Blue-Green Algae

Description: Citrilline has been isolated and identified from extracts of Nostoc muscorum. All members of the Cyanophyceae hitherto investigated show a relatively large amount of the CO fixed during photosynthesis in citrulline (ranging as high as 20% in Nostoc) when compared to the trace amounts found in the Chlorophyceae. Nostoc also has the ability to fix C{sup 14} in citrulline during dark fixation, but at a rate slower than in light. As no free urea or arginine was found in Nostoc, it is likely that citrulline is functioning in reactions other than those leading to arginine and urea synthesis. Other possible functions for citrulline are briefly discussed.
Date: August 28, 1956
Creator: Linko, Pekka; Holm-Hansen, O.; Bassham, J.A. & Calvin, M.
Partner: UNT Libraries Government Documents Department

The Relationship Between the Metabolic Pools of Photosynthetic andRespiratory Intermediates

Description: Using radioactive carbon dioxide, an attempt has been made to distinguish the various pools of intermediary metabolism which may be physically or chemically separate within the cell. Some correlation between the structural elements of the cells and these pools appears possible.
Date: July 1, 1958
Creator: Moses, V.; Calvin, M.; Holm-Hansen, O. & Bassham, J.A.
Partner: UNT Libraries Government Documents Department


Description: The metabolism of C{sup 14} labeled glycolic acid by Scenedesmus has been studied using radiochromatographic techniques for the separation and identification of products. When the pH of the medium was 2.8, appreciable assimilation occurred. The products were identical to those observed in C{sup 14}O{sub 2} photosynthesis. A major reaction anaerobically in the dark resulted in incorporation of C{sup 14} in almost equal amounts in the glycine and serine reservoirs. When the algae were illuminated, a diminution in the amount of glycine was observed.
Date: September 11, 1950
Creator: Schou, L.; Benson, A.A.; Bassham, J.A. & Calvin, M.
Partner: UNT Libraries Government Documents Department


Description: Although there has been considerable progress toward an understanding of the processes of photosyntehsis in recent years, the advances have been followed rather lcosely by symposia, monographs and reviews of the subject matter, particularly during the last three years. In view of the comprehensive coverage it would appear that the present review might very well be limited to a discussion of certain subjects of special interest to the authors and some with which they are especially familiar. These are (1) the extensive discussion by Warburg and his co-workers of their proposal for the existence of a light induced oxygen absorption (and corresponding carbon dioxide evolution) which can amount to three or four times the net oxygen evolution by the same light; and (2) the discovery of the early participation of 7 and 5 carbon sugars in carbon dioxide reduction in photosyntehsis together with some observations on the kinetics of the metabolic transformations. While it is true that a considerable number of significant publications have appears in other aspects of photosynthesis (the Hill reaction and its coupling with carbon dioxide reduction; photochemistry of chlorophyll and related synthetic materials as model reactions in relatively simple defined physical systems; transfer of light energy within the pigment systems) it is felt that they represent confirmation and extension of ideas which have already been discussed in a variety of earlier reviews and that a re-evaluation of them might very well be postponed until a later time.
Date: March 1, 1952
Creator: Calvin, M.; Bassham, J.A.; Benson, A.A. & Massini, P.
Partner: UNT Libraries Government Documents Department


Description: The conclusions which have been drawn from the results of C{sup 14}O{sub 2} fixation experiments with a variety of plants are developed in this paper. The evidence for thermochemical reduction of carbon dioxide fixation intermediates is presented and the results are interpreted from such a viewpoint.
Date: April 1, 1950
Creator: Calvin, M.; Bassham, J .A.; Benson, A.A.; Lynch, V.; Ouellet, C.; Schou, L. et al.
Partner: UNT Libraries Government Documents Department

The Path of Carbon in Photosynthesis. XIV.

Description: It seems hardly necessary to repeat to an audience of this kind the importance of the process known as photosynthesis in the interaction and the interdependence of organisms and in the very existence of life as we know it. This process by which green plants are able to capture electromagnetic energy in the form of sunlight and transform it into stored chemical energy in the form of a wide variety of reduced (relative to carbon dioxide) carbon compounds provides the only major source of energy for the maintenance and propagation of all life.
Date: June 30, 1951
Creator: Calvin, Melvin; Bassham, J.A.; Benson, A.A.; Kawaguchi, S.; Lynch, V.H.; Stepka, W. et al.
Partner: UNT Libraries Government Documents Department

The Path of Carbon in Photosynthesis, XV. Ribulose andSedoheptulose

Description: The intermediates of carbon dioxide reduction by plants include phosphorylated derivatives of hydroxy acids and sugars. Their identification becane possible when the use of labeled carbon dioxide permitted discrimination between the earliest products and the many other components of photosynthetic tissues. A number of compounds were identified by virtue of the chemical and physical properties of the radioactive compounds in tracer amounts and by direct comparison of these properties with those of suspected known metabolic intermediates. It became apparent that several labeled compounds found in short exposures to radioactive carbon dioxide were not substances previously identified as metabolic intermediates. Two phosphate esters in particular were observed in the products of the first few seconds of steady-state photosynthesis by all the photosynthetic microorganisms and higher plants examined in this laboratory. These esters have been isolated by paper chromatography in tracer quantities and enzymatically hydrolyzed to give two sugars, ribulose and sedoheptulose. This paper contains a description of the chemical identification of these sugars and some observations and suggestions regarding the function of their esters. The general importance of these compounds in photosynthesis was surmized before their identification. The products of photosynthesis with C{sup 14}O{sub 2} by each plant included phosphate esters of the same two then unknown compounds in addition to those of the expected glucose, fructose, dihydroxyacetone and glyceric acid. As the time of steady-state photosynthesis in C{sup 14}O{sub 2} decreased, the fractions of total fixed radiocarbon in the esters of the two unidentified compounds increased.
Date: January 1, 1952
Creator: Benson, A.A.; Bassham, J.A.; Calvin, M.; Hall, A.G.; Hirsch, H.; Kawaguchi, S. et al.
Partner: UNT Libraries Government Documents Department

The Path of Carbon in Photosynthesis. XXI. The Cyclic Regenerationof Carbon Dioxide Acceptor

Description: Photosynthesizing plants have been exposed to C{sup 14}O{sub 2} for short periods of time (0.4 to 15 sec.) and the products of carbon dioxide reduction analyzed by paper chromatography and radio autography. Methods have been developed for the degradation of ribulose and sedoheptulose. These sugars, obtained as their phosphate esters from the above C{sup 14}O{sub 2} exposures and from other experiments, have been degraded and their distribution of radiocarbon determined. The distribution of radiocarbon in these sugars, and other data, indicate that sedoheptulose phosphate and ribulose diphosphates are formed during photosynthesis from triose and hexose phosphates, the latter being synthesized, in turn, by the reduction of 3-phosphoglyceric acid.
Date: October 1, 1953
Creator: Bassham, J.A.; Benson, A.A.; Kay, Lorel D.; Harris, Anne Z.; Wilson, A.T. & Calvin, M.
Partner: UNT Libraries Government Documents Department

The Path of Carbon in Photosynthesis. XVII. Phosphorus Compoundsas Intermediates in Photosynthesis

Description: Studies of carbon dioxide fixation in green plants using the C{sup 14} isotope have shown that in very short times phosphoglyceric acid contains most of the radioactivity. The tracer is present almost entirely in the carboxyl group. The importance of organic phosphates in the subsequent metabolism of phosphoglyceric acid can be seen from the accompanying photographs.
Date: July 8, 1952
Creator: Buchanan, J.G.; Bassham, J.A.; Benson, A.A.; Bradley, D.F.; Calvin, M.; Daus, L.L. et al.
Partner: UNT Libraries Government Documents Department