Path Of Carbon In Photosynthesis Research Articles

Source of 12C in Calvin-Benson cycle intermediates and isoprene emitted from plant leaves fed with 13CO2.

Feeding 14CO2 was crucial to uncovering the path of carbon in photosynthesis. Feeding 13CO2 to photosynthesizing leaves emitting isoprene has been used to develop hypotheses about the sources of carbon for the methylerythritol 4-phosphate pathway, which makes the precursors for terpene synthesis in chloroplasts and bacteria. Both photosynthesis and isoprene studies found that products label very quickly (<10 min) up to 80-90% but the last 10-20% of labeling requires hours indicating a source of 12C during photosynthesis and isoprene emission. Furthermore, studies with isoprene showed that the proportion of slow label could vary significantly. This was interpreted as a variable contribution of carbon from sources other than the Calvin-Benson cycle (CBC) feeding the methylerythritol 4-phosphate pathway. Here, we measured the degree of label in isoprene and photosynthetic metabolites 20 min after beginning to feed 13CO2. Isoprene labeling was the same as labeling of photosynthesis intermediates. High temperature reduced the label in isoprene and photosynthesis intermediates by the same amount indicating no role for alternative carbon sources for isoprene. A model assuming glucose, fructose, and/or sucrose reenters the CBC as ribulose 5-phosphate through a cytosolic shunt involving glucose 6-phosphate dehydrogenase was consistent with the observations.

Benson-Bassham-Calvin cycle contribution to the organic life on our planet

The review is devoted to the outstanding contributions to the path of carbon in photosynthesis by Professor Emeritus Andrew A. Benson, on the occasion of his death at the age of 97, on January 16, 2015. Benson is the legendary co-discoverer of the photosynthetic reductive pentose phosphate cycle, known to every student of photosynthesis as the Benson-Bassham-Calvin cycle. This pathway evolved into the dominant assimilation mechanism for atmospheric carbon into metabolites. The fundamental ecological and biochemical optimization and evolutionary stability of this mechanism unfolded elegantly in Benson’s hands, as he was the first to recognize the building blocks for the synthesis of essential organic compounds that satisfy the energetic needs and demands of most life forms. Photosynthetic carbon metabolism together with other energy and oxidative reactions and secondary biosynthetic processes are critical for the formation of organic matter; and, thereby, the Benson-Bassham-Calvin cycle ensures maintenance of the biosphere.

Andrew Benson honored on birthday № 97

We present a brief account of the 97th birthday celebration of Andrew A. Benson, a scientific legend who is known, among other contributions, for his pioneering work on the path of carbon in photosynthesis (the Calvin-Benson cycle).

The Path of Carbon in Photosynthesis: How to Discover a Biochemical Pathway

This paper traces the discovery of the so-called Calvin–Benson cycle of photosynthesis, that is, the cyclic sequence of reactions through which the reduction of carbon dioxide to carbohydrates is accomplished in the green organs of plants. This pathway, which herein is understood to be the model of a mechanism, was elucidated by a research team of the University of California at Berkeley in the years 1946–1954. The sequence of working hypotheses is described, with a focus on the methodology and heuristic strategies of the research group. While it has often been underlined that the group’s innovative mixture of new techniques (radiotracers and paper chromatography) was the secret of its success, this paper describes how these techniques were applied: it transpires that the group combined the classic difference test, the interpretation of which was guided by additional heuristic assumptions and mechanistic thinking, with a specific kind of analogical inference, namely, the transfer of causal knowledge from one context to another.

Last days in the old radiation laboratory (ORL), Berkeley, California, 1954

Govindjee, the founding editor of the Historical Corner of Photosynthesis Research, invited me 3 years ago to tell the story of why I left Melvin Calvin’s laboratory in the mid 1950s long before the 1961 Nobel Prize in Chemistry was awarded to Calvin for the path of carbon in photosynthesis. I have already written my scientific perspective on this topic (see Benson (Photosynth Res 73:29–49, 2002); also see Bassham (Photosynth Res 76:35–52, 2003) as he was also a major player in this research). Here, I present my recollections of my last days in the old radiation laboratory (ORL) at Berkeley, California. References have been added by Govindjee for the benefit of the readers.

Celebrating Andrew Alm Benson’s 93rd birthday

We celebrate Andy Benson's 93rd birthday on September 24, 2010 through this Editorial. This short account about Andy Benson should serve as a prelude to the short article that Andy has written for the entire photosynthesis community, which gives a glimpse of why he left the field of the "path of carbon in photosynthesis," when he had already discovered, together with Melvin Calvin, James Alan Bassham, and others, most of the major steps in what we now call the Calvin-Benson cycle.

The Path of Carbon in Photosynthesis. XXV. Plant and Algal Growth Responses to Glycopyranosides

ABSTRACT Substituted glycopyranosides were applied to various plant species as foliar and root treatments, with and without nutrient supplements, and growth was compared to untreated or nutrient controls. When formulated with specific fertilizers, particularly available nitrogen, methyl and ethyl glycopyranosides significantly enhanced the overall growth of vascular plants compared to controls provided with the same nutrients. In contrast, vascular plants treated with alkylglycopyranosides without nutrients showed growth equivalent to that of untreated controls. Nitrogen-supplemented alkylglycopyranosides provided as foliar applications of 100 mM, or as root treatments between 35 and 50 mM, consistently enhanced root and shoot productivity. In addition to the vascular plant species tested, the brown alga Laminaria saccharina exhibited significant growth enhancement over nutrient controls when treated with alkylglycopyranosides supplemented with nutrients, especially under low irradiance. Overall, these results indicate that growth of photosynthetic organisms is enhanced by exogenous alkylglycopyranosides supplemented with nitrogen and micronutrients, but not by alkylglycopyranosides alone.

Professor Andrew A. Benson: inspirational mentor

An active sea-going scientist, Professor Andrew A. Benson has an acclaimed reputation for innovative biochemistry, whether he is studying the path of carbon in photosynthesis, the lipid metabolism of biological membranes, the metabolism of arsenic in aquatic plants or calcitonin production in spawning salmon—to name only four of his thousand interests! He infects everyone whom he meets with his enthusiasm for scientific exploration, and the joys of discovery, whether his own or that of others. This engagement with others has allowed him to become a truly memorable mentor, particularly among the Australian science community, and he is treasured for it. Back in the early 1960s, after working with pioneers in radioactive carbon in the UC Berkeley’s Lawrence Radiation Laboratory to isolate the first products of carbon dioxide fixation in photosynthesis (Benson 2002)—truly brilliant achievements—Professor Benson moved to the Scripps Institution of Oceanography at La Jolla, California, where he became the founding chair of the Marine Biology Department, and later Director of the Physiological Research Laboratory and associate Director of the Institution. In keeping with his wide interests, the objective of his Marine Biology group was to understand the fundamental problems of biology and medicine, through a better understanding of marine organisms and the manner in which they adapt to life in the sea. Molecular, biochemical, physiological and ecological characteristics of marine plants, animals, and bacteria were all utilized in this search. This approach was stimulated by the aquisition of the research vessel RV Alpha Helix in 1966, a national facility, funded by the US National Science foundation, but managed by Scripps. Professors Benson and Scholander were intimately involved in the planning and devising of its scientific programmes. The facilities of this floating laboratory attracted many collaborating investigators from American and foreign institutions, and it was planned that the vessel would take groups of medical scientists and biologists to far corners of the marine world where they could learn from nature and each other. No longer scientists would be limited to the study of rats, mice and rabbits in their laboratories. They could find more specialized biological systems in the sea for understanding human disorders and problems (Benson 1992). The maiden voyage from Scripps to the Australian Great Barrier Reef in 1966 was no exception. This ‘‘Billabong’’ expedition had many objectives, including the study of reef symbioses between microscopic algae and reef building corals and Tridacna clams, salt and water regulation of mangroves, neurophysiologial studies of marine invertebrates, temperature regulation of reptiles, and physiological investigations of the ‘‘mermaid’’ sirenians—the gentle dugongs. I was to join Scripps cruise leader Professor Francis Haxo with a brief to identify the photosynthetic pigments of the phylogenetically unknown golden brown algae living symbiotically within reef animals, for which I had just developed a new micro-method. However, my first personal encounter with Professor Andy Benson was not on the Alpha Helix but on the remote air-field in far north Queensland adjacent to Princess Charlotte Bay (Fig. 1) when I was en route from Sydney to the ship to join her 1966 maiden voyage. Disembarking from the tiny twin-engined Cessna aircraft of the Bush Pilots Airways, I was greeted on the ‘‘air-field’’—a rough Queensland S. W. Jeffrey (&) CSIRO Division of Marine and Atmospheric Research, GPO Box 1538, Hobart, TAS 7001, Australia e-mail: shirley.jeffrey@csiro.au

A re-investigation of the path of carbon in photosynthesis utilizing GC/MS methodology. Unequivocal verification of the participation of octulose phosphates in the pathway

A GC/EIMS/SIM methodology has been developed to re-examine the path of carbon in photosynthesis. Exposing isolated spinach chloroplasts to 13CO2 on a solid support for a defined period followed by quenching and work-up provided a mixture of labelled sugar phosphates. After enzymatic dephosphorylation and derivatization, the Mox-TMS sugars were analysed using the above method. The purpose of the study was to try to calculate the atom% enrichment of 13C in as many of the individual carbons in each of the derivatized sugars as was practical using diagnostic fragment ions. In the event, only one 45 s experiment provided sufficient data to enable a range of enrichment values to be calculated. This confirmed that D-glycero-D-altro-octulose phosphate was present in the chloroplasts and was heavily labelled in the C4, C5 and C6 positions, in keeping with the hypothesis that it had an inclusive role and a labelling pattern consistent with a new modified pathway of carbon in photosynthesis.

The early history of32P as a radioactive tracer in biochemical research: A personal memoir

The concept of using radioactive isotopes as "tracers" of chemical conversions was conceived and developed by inorganic chemist Georg de Hevesy (Nobel Laureate in Chemistry 1943). In 1935, he began to apply the technique to various biological processes using (32) P, and his experiments revealed the dynamic character of physiology and metabolism. Following de Hevesy's lead, Samuel Ruben (University of California, Berkeley) exploited (32) P in 1937-38 for investigation of phospholipid metabolism. Between 1937 and 1940, Ruben and colleague Martin Kamen spearheaded tracer studies in various biological systems using (32) P, short-lived (11) C, and other radioactive isotopes. During this period, Kamen was responsible for cyclotron-produced radioactive tracers and was able to sustain de Hevesy's research by supplying him with (32) P. In 1940, Ruben and Kamen discovered long-lived (14) C, which later proved to be a very powerful tool for analysis of complex biochemical processes, such as the path of carbon in photosynthesis. Between 1946 and 1950, (32) P was used in studies of bacteriophage replication and photosynthetic metabolism. This memoir surveys the history of these early investigations.

Paving the path.

Fortuitous preparation and experiences led to the opportunity to use radioactive carbon dioxides to discern the path of carbon in photosynthesis. The search for the CO2 acceptor led to recognition of the growth stimulatory effect of methanol and its derivatives. With the techniques developed, radiochromatographic exploration led to discovery of major membrane lipids containing phosphorus, sulfur, and arsenic.

Following the path of carbon in photosynthesis: a personal story.

Chronological recognition of the intermediates and mechanisms involved in photosynthetic carbon dioxide fixation is delineated. Sam Ruben and Martin Kamen's development of application of radioactive carbon for the study of carbon dioxide fixation provided impetus and techniques for following the path of carbon in photosynthesis. Discovery The identity of the primary carboxylation enzyme and its identity with the major protein of photosynthetic tissues ('Fraction 1' protein of Sam Wildman) is reviewed. Memories are dimmed by sixty years of exciting discoveries exploration in newer fields [see Benson 2002 (Annu Rev Plant Biol 53: 1-25), for research and perspectives beyond the early Berkeley days].

Mass spectrometric studies of the path of carbon in photosynthesis: positional isotopic analysis of 13C‐labelled C4 to C7 sugar phosphates

The (EIMS) electron ionization mass spectrometric fragmentation patterns of the methoxime- and ethoxime-trimethylsilyl (TMS) derivatives of C(4) to C(7) sugars involved as phosphates in the Calvin pathway of photosynthesis in plants were analysed by gas chromatography/EIMS using specifically labelled (13)C analogs. In general, most but not all of the major ions in the mass spectra arise from single carbon-carbon bond cleavages of the straight-chain derivatives. The results confirm that GC/MS of the alkoxime-TMS derivatives is a viable method for measuring (13)C incorporations at individual carbon atoms in each of the sugar phosphates during photosynthetic experiments with (13)CO(2).

Paving the path

The Path of Carbon in Photosynthesis evolved in the minds of Sam Ruben and Martin Kamen as they followed incorporation of radioactive 11CO2 in their many experiments, 1938 to 1942. With the concepts and collaboration of C. B. van Niel it became clear that reduction of CO2 can occur in the dark and may require processes similar to bacterial systems. It could not involve the century-old A. von Baeyer theory's photochemical reduction of CO2 adsorbed on chlorophyll which had guided decades of painstaking efforts, of R. Willstatter and A. Stoll and many others, in vain searches for formaldehyde. In 1942 Sam Ruben gave me all of his home-made 14CO2 to look for the first steps of the path of carbon in photosynthesis. Measurements were tedious and activities low but progress was real. Liquid-liquid partition of the radioactivity indicated chemical properties of the products and their derivatives. Interrupted by the war and Sam Ruben?s tragic accidental death, I accepted Melvin Calvin's invitation to continue The Path and we established our lab in the Old Radiation Laboratory next to Ernest Lawrence's cyclotron. Pre-illuminated algae rapidly reduced 14CO2 in the dark! Simple 'partition'-based separations on paper chromatograms extended the earlier methodology. Sedoheptulose and ribulose made surprise appearances. Soon it became clear that Nature had selected ribulose bisphosphate as its universal CO2 acceptor molecule. Finally, our isolation of carboxydismutase in 1954 revealed its identity with Sam Wildman's Fraction 1 protein. The Path was paved with one of this planet's major proteins!

The path of carbon in photosynthesis: improved crop yields with methanol.

Foliar sprays of aqueous 10-50% methanol increased growth and development of C3 crop plants in arid environments. The effects of low levels (< 1 ml per plant) of methanol were observed for weeks after the brief time necessary for its rapid metabolism. Within several hours, foliar treatment with methanol resulted in increased turgidity. Plants treated with nutrient-supplemented methanol showed up to 100% increases in yields when maintained under direct sunlight in desert agriculture. In the shade and when winter crops were treated with methanol, plants showed no improvement of growth. When repeatedly treated with nutrient-supplemented methanol, shaded plants showed symptoms of toxicity. Repeated methanol treatments with glycine caused increased turgidity and stimulated plant growth without injury under indirect sunlight, but indoors with artificial illumination, foliar damage developed after 48 hr. Addition of glycerophosphate to glycine/methanol solutions allowed treatment of artificially illuminated plants indoors without injury. Plants with C4 metabolism showed no increase in productivity by methanol treatment. Plants given many applications of aqueous methanol showed symptoms of nutrient deficiency. Supplementation with a source of nitrogen sustained growth, eliminating symptoms of deficiency. Adjustment of carbon/nitrogen ratios was undertaken in the field by decreasing the source of nitrogen in the final application, resulting in early maturation; concomitantly, irrigation requirements were reduced.

Mass spectrometric studies of the path of carbon in photosynthesis: Positional isotopic analysis of 13C‐labelled 2‐octulose phosphates

AbstractThe electron impact mass spectrometric fragmentation patterns of the per‐O‐trimethylsilyl (TMS) and alkoxime‐TMS derivatives of D‐glycerol‐D‐altro and D‐glycerol‐D‐ido‐octuloses were fully analysed using seven specifically labelled 13C analogues. Many of the more intense‐ ions in the spectra of the per‐O‐TMS furanose and pyranose derivatives have more than one origin. On the other hand, the mass spectra of the straight‐chain methoxime and ethoxime hepta‐O‐TMS derivatives contain ions each of which in general originares from a single cleavage process. This makes gas chromatography/mass spectrometry of the aikoxime‐TMS derivatives a suitable method for monitoring 13C incorporations at individual carbon atoms in the corresponding octulose phosphates during photosynthesis experiments with 13CO2.

The path of carbon in photosynthesis—Back to the future

F ive to ten billion tons of carbon dioxide from fossil-fuel based energy production and from deforestation burnoff are entering the atmosphere annually. Suggested solutions to this massive accumulation include alternate energy sources, energy conservation, massive reforestation and, in the long term, increased use of natural carbon dioxide reservoirs such as the oceans. Relatively neglected in global planning efforts are the opportunities which may lie in the genetic engineering of the two key enzymes in photosynthetic carbon dioxide fixation, phosphoribulokinase (PRK) and ribulosebisphosphate carboxylase/oxygenase (Rubisco). Even the smallest increase in the efficiency of CO 2 fixation by Rubisco would remove significant amounts of CO 2 from the atmosphere. (A 1% increase on a worldwide basis would theoretically fix 1.5.109 additional tons of CO 2 per year. It is estimated that 1.5.1011 tons of CO 2 are sequestered annually by photosynthesis.) Present funding in this area is modest by any standards and it is surprising that a concerted research program to achieve both an understanding and enhancement of the Rubisco reaction has not been implemented nor, perhaps, even seriously considered at a national level. With this in mind, the purpose of this review is to detail the background and research which led to the first isolation and characterization

The Path of Carbon in Photosynthesis by Chlamydomonas segnis Adapting to Low and High Carbon Dioxide Tension

Summary The kinetics of 14 C-incorporation into the major intermediates of the C2 photorespiratory carbon oxidation (C2PCO) and the C3 photosynthetic carbon reduction (C3PCR) cycles, and into C4 compounds were determined in Chlamydomonas segnis during photosynthesis at sub-optimal concentration of inorganic carbon. These and the level of carbonic anhydrase (CA) activity were compared in zoospores, at mid G 1 -phase of the cell cycle, adapting (i.e. for 4h) and adapted (i.e. for many generations) to air and 5 % CO 2 . The results indicated that the suppression of the C2PCO cycle was an early event in the process of zoospore adaptation to air and was accompanied by a limited 14 C-incorporation into malate and aspartate. The 14 C in these acids did not exceed 14 % of the total 14 C recovered in early photosynthates. This and the lack of 14 C flow from C4 acids to the intermediates of the C3PCR cycle provided evidence that the C4 pathway was absent in zoospores capable of suppressing the C2PCO cycle. However, the ratio of 14 C in malate and aspartate to that in glycolate and glycine after 5–10 s photosynthesis was higher (2.26–2.72) in zoospores adapting or adapted to 5 % CO 2 than to air (1.35–1.46). The high C4/C2 ratio in such zoospores with an active C2PCO cycle could be explained in terms of their ability to refix photorespiratory CO 2 via β-carboxylation. In zoospores adapting to air, the acquisition of a relatively high level fo CA activity appeared to be unnecessary for the stimulation of the C3PCR cycle.

The Effect of Inhibitors on the Path of Carbon in Photosynthesis by Chlorella at Low Partial Pressures of CO2

Methylamine has previously been shown to uncouple phosphorylation in isolated chloroplasts. Results presented here are consistent with its having a similar action in Chlorella. It both stimulates oxygen production and inhibits carbon dioxide fixation. It markedly affects the distribution of carbon within the photosynthetic carbon reduction cycle at low partial pressures of carbon dioxide, decreasing the amount of sugar diphosphates and increasing that of PGA. The production of glycollate and glycine is diminished in the presence of methylamine but there is little effect on sucrose.

The Effect of Inhibitors on the Path of Carbon in Photosynthesis by Chlorella at Low Partial Pressures of CO2

The Effect of Inhibitors on the Path of Carbon in Photosynthesis by Chlorella at Low Partial Pressures of CO2