Running Head: Control and Adjustment of the Rate of Photosynthesis Above Present CO(sub 2) Levels; FINAL

International Nuclear Information System (INIS)

Ball, J. Timothy

1996-01-01

The adjustment of photosynthesis to different environmental conditions and especially to elevated CO(sub 2) is often characterized in terms of changes in the processes that establish (limit) the net CO(sub 2) assimilation rate. At slightly above present ambient pCO(sub 2) light-saturated photosynthetic responses to CO(sub 2) depart limitation by the catalytic capacity of tissue rubisco content. An hypothesis attributing this departure to limited thylakoid reaction/electron transport capacity is widely accepted, although we find no experimental evidence in the literature supporting this proposition.. The results of several tests point to the conclusion that the capacity of the thyiakoid reactions cannot be generally responsible for the deviation from rubisco limitation. This conclusion leaves a significant gap in the interpretation of gas exchange responses to CO(sub 2). Since the inputs to the photosynthetic carbon reduction cycle (CO(sub 2) and photon-capture/electron-transport products) do not limit photosynthesis on the shoulder of the A=f(c(sub i)) curve, the control of photosynthesis can be characterized as: due to feedback. Several characteristics of gas exchange and fluorescence that occur when steady-states in this region are perturbed by changes in CO(sub 2) or O(sub 2) suggest significant regulation by conditions other than directly by substrate RuBP levels. A strong candidate to explain these responses is the triose-phosphate flux/ inorganic phosphate regulatory sequence, although not all of the gas exchange characteristics expected with ''TPU-limitation'' are present (e.g. oxygen-insensitive photosynthesis). Interest in nitrogen allocation between rubisco and light capture/electron transport as the basis for photosynthetic adjustment to elevated CO(sub 2) may need to be reconsidered as a result of these findings. Contributors to the feedback regulation of photosynthesis (which may include sucrose phosphate synthase and fructose bisphosphatase activities

DOE final technical report 3/1997 to 2/2005

International Nuclear Information System (INIS)

Gross, Franz L.

2005-01-01

DOE final technical report 3/1997 to 2/2005 This grant supported basic theoretical research into the derivation (from relativistic field theories) of relativistic equations for few body systems, with practical applications to the properties of 2 and 3 nucleon systems and to the nature of few-quark systems

77 FR 47495 - Final Priority; Technical Assistance on State Data Collection, Analysis, and Reporting-National...

Science.gov (United States)

2012-08-08

... Priority; Technical Assistance on State Data Collection, Analysis, and Reporting--National IDEA Technical... 34 CFR Chapter III [CFDA Number 84.373Z] Final Priority; Technical Assistance on State Data Collection, Analysis, and Reporting--National IDEA Technical Assistance Center on Early Childhood...

Technical area status report for low-level mixed waste final waste forms

International Nuclear Information System (INIS)

Mayberry, J.L.; DeWitt, L.M.; Darnell, R.

1993-08-01

The Final Waste Forms (FWF) Technical Area Status Report (TASR) Working Group, the Vitrification Working Group (WG), and the Performance Standards Working Group were established as subgroups to the FWF Technical Support Group (TSG). The FWF TASR WG is comprised of technical representatives from most of the major DOE sites, the Nuclear Regulatory Commission (NRC), the EPA Office of Solid Waste, and the EPA's Risk Reduction Engineering Laboratory (RREL). The primary activity of the FWF TASR Working Group was to investigate and report on the current status of FWFs for LLNM in this TASR. The FWF TASR Working Group determined the current status of the development of various waste forms described above by reviewing selected articles and technical reports, summarizing data, and establishing an initial set of FWF characteristics to be used in evaluating candidate FWFS; these characteristics are summarized in Section 2. After an initial review of available information, the FWF TASR Working Group chose to study the following groups of final waste forms: hydraulic cement, sulfur polymer cement, glass, ceramic, and organic binders. The organic binders included polyethylene, bitumen, vinyl ester styrene, epoxy, and urea formaldehyde. Section 3 provides a description of each final waste form. Based on the literature review, the gaps and deficiencies in information were summarized, and conclusions and recommendations were established. The information and data presented in this TASR are intended to assist the FWF Production and Assessment TSG in evaluating the Technical Task Plans (TTPs) submitted to DOE EM-50, and thus provide DOE with the necessary information for their FWF decision-making process. This FWF TASR will also assist the DOE and the MWIP in establishing the most acceptable final waste forms for the various LLMW streams stored at DOE facilities

76 FR 18624 - Research, Technical Assistance and Training Programs: Notice of Final Circular

Science.gov (United States)

2011-04-04

... to FTA Circular 6100.1D, Research and Technical Assistance Training Program: Application Instructions... DEPARTMENT OF TRANSPORTATION Federal Transit Administration Research, Technical Assistance and Training Programs: Notice of Final Circular AGENCY: Federal Transit Administration (FTA), DOT. ACTION...

AIMES Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Katz, Daniel S [Univ. of Illinois, Urbana-Champaign, IL (United States). National Center for Supercomputing Applications (NCSA); Jha, Shantenu [Rutgers Univ., New Brunswick, NJ (United States); Weissman, Jon [Univ. of Minnesota, Minneapolis, MN (United States); Turilli, Matteo [Rutgers Univ., New Brunswick, NJ (United States)

2017-01-31

This is the final technical report for the AIMES project. Many important advances in science and engineering are due to large-scale distributed computing. Notwithstanding this reliance, we are still learning how to design and deploy large-scale production Distributed Computing Infrastructures (DCI). This is evidenced by missing design principles for DCI, and an absence of generally acceptable and usable distributed computing abstractions. The AIMES project was conceived against this backdrop, following on the heels of a comprehensive survey of scientific distributed applications. AIMES laid the foundations to address the tripartite challenge of dynamic resource management, integrating information, and portable and interoperable distributed applications. Four abstractions were defined and implemented: skeleton, resource bundle, pilot, and execution strategy. The four abstractions were implemented into software modules and then aggregated into the AIMES middleware. This middleware successfully integrates information across the application layer (skeletons) and resource layer (Bundles), derives a suitable execution strategy for the given skeleton and enacts its execution by means of pilots on one or more resources, depending on the application requirements, and resource availabilities and capabilities.

NCSU reactor sharing program. Final technical report

International Nuclear Information System (INIS)

Perez, P.B.

1997-01-01

The Nuclear Reactor Program at North Carolina State University provides the PULSTAR Research Reactor and associated facilities to eligible institutions with support, in part, from the Department of Energy Reactor Sharing Program. Participation in the NCSU Reactor Sharing Program continues to increase steadily with visitors ranging from advance high school physics and chemistry students to Ph.D. level research from neighboring universities. This report is the Final Technical Report for the DOE award reference number DE-FG05-95NE38136 which covers the period September 30, 1995 through September 30, 1996

Anoxygenic Photosynthesis Controls Oxygenic Photosynthesis in a Cyanobacterium from a Sulfidic Spring

KAUST Repository

Klatt, Judith M.; Alnajjar, Mohammad Ahmad; Yilmaz, Pelin; Lavik, Gaute; de Beer, Dirk; Polerecky, Lubos

2015-01-01

Before the Earth's complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39, in which this versatility is still conserved, and we show that the transition between the two photosynthetic modes follows a surprisingly simple kinetic regulation controlled by this organism's affinity for H2S. Specifically, oxygenic photosynthesis is performed in addition to anoxygenic photosynthesis only when H2S becomes limiting and its concentration decreases below a threshold that increases predictably with the available ambient light. The carbon-based growth rates during oxygenic and anoxygenic photosynthesis were similar. However, Pseudanabaena FS39 additionally assimilated NO3 - during anoxygenic photosynthesis. Thus, the transition between anoxygenic and oxygenic photosynthesis was accompanied by a shift of the C/N ratio of the total bulk biomass. These mechanisms offer new insights into the way in which, despite nutrient limitation in the oxic photic zone in the mid-Proterozoic oceans, versatile cyanobacteria might have promoted oxygenic photosynthesis and total primary productivity, a key step that enabled the complete oxygenation of our planet and the subsequent diversification of life.

Anoxygenic Photosynthesis Controls Oxygenic Photosynthesis in a Cyanobacterium from a Sulfidic Spring

KAUST Repository

Klatt, Judith M.

2015-03-15

Before the Earth\\'s complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39, in which this versatility is still conserved, and we show that the transition between the two photosynthetic modes follows a surprisingly simple kinetic regulation controlled by this organism\\'s affinity for H2S. Specifically, oxygenic photosynthesis is performed in addition to anoxygenic photosynthesis only when H2S becomes limiting and its concentration decreases below a threshold that increases predictably with the available ambient light. The carbon-based growth rates during oxygenic and anoxygenic photosynthesis were similar. However, Pseudanabaena FS39 additionally assimilated NO3 - during anoxygenic photosynthesis. Thus, the transition between anoxygenic and oxygenic photosynthesis was accompanied by a shift of the C/N ratio of the total bulk biomass. These mechanisms offer new insights into the way in which, despite nutrient limitation in the oxic photic zone in the mid-Proterozoic oceans, versatile cyanobacteria might have promoted oxygenic photosynthesis and total primary productivity, a key step that enabled the complete oxygenation of our planet and the subsequent diversification of life.

Photosynthesis in the Archean era.

Science.gov (United States)

Olson, John M

2006-05-01

The earliest reductant for photosynthesis may have been H2. The carbon isotope composition measured in graphite from the 3.8-Ga Isua Supercrustal Belt in Greenland is attributed to H2-driven photosynthesis, rather than to oxygenic photosynthesis as there would have been no evolutionary pressure for oxygenic photosynthesis in the presence of H2. Anoxygenic photosynthesis may also be responsible for the filamentous mats found in the 3.4-Ga Buck Reef Chert in South Africa. Another early reductant was probably H2S. Eventually the supply of H2 in the atmosphere was likely to have been attenuated by the production of CH4 by methanogens, and the supply of H2S was likely to have been restricted to special environments near volcanos. Evaporites, possible stromatolites, and possible microfossils found in the 3.5-Ga Warrawoona Megasequence in Australia are attributed to sulfur-driven photosynthesis. Proteobacteria and protocyanobacteria are assumed to have evolved to use ferrous iron as reductant sometime around 3.0 Ga or earlier. This type of photosynthesis could have produced banded iron formations similar to those produced by oxygenic photosynthesis. Microfossils, stromatolites, and chemical biomarkers in Australia and South Africa show that cyanobacteria containing chlorophyll a and carrying out oxygenic photosynthesis appeared by 2.8 Ga, but the oxygen level in the atmosphere did not begin to increase until about 2.3 Ga.

Improving Photosynthesis

Science.gov (United States)

Evans, John R.

2013-01-01

Photosynthesis is the basis of plant growth, and improving photosynthesis can contribute toward greater food security in the coming decades as world population increases. Multiple targets have been identified that could be manipulated to increase crop photosynthesis. The most important target is Rubisco because it catalyses both carboxylation and oxygenation reactions and the majority of responses of photosynthesis to light, CO2, and temperature are reflected in its kinetic properties. Oxygenase activity can be reduced either by concentrating CO2 around Rubisco or by modifying the kinetic properties of Rubisco. The C4 photosynthetic pathway is a CO2-concentrating mechanism that generally enables C4 plants to achieve greater efficiency in their use of light, nitrogen, and water than C3 plants. To capitalize on these advantages, attempts have been made to engineer the C4 pathway into C3 rice (Oryza sativa). A simpler approach is to transfer bicarbonate transporters from cyanobacteria into chloroplasts and prevent CO2 leakage. Recent technological breakthroughs now allow higher plant Rubisco to be engineered and assembled successfully in planta. Novel amino acid sequences can be introduced that have been impossible to reach via normal evolution, potentially enlarging the range of kinetic properties and breaking free from the constraints associated with covariation that have been observed between certain kinetic parameters. Capturing the promise of improved photosynthesis in greater yield potential will require continued efforts to improve carbon allocation within the plant as well as to maintain grain quality and resistance to disease and lodging. PMID:23812345

The social acceptance of artificial photosynthesis: towards a conceptual framework

Science.gov (United States)

Sovacool, Benjamin K.; Gross, Allan

2015-01-01

Advancements in artificial photosynthesis have the potential to radically transform how societies convert and use energy. Their successful development, however, hinges not only on technical breakthroughs, but also acceptance and adoption by energy users. This article introduces a conceptual framework enabling analysts, planners and even investors to determine environments where artificial photosynthesis may thrive, and those where it may struggle. Drawn from work looking at the barriers and acceptance of solar photovoltaic and wind energy systems, the article proposes that social acceptance has multiple dimensions—socio-political, community and market—that must be met holistically in order for investors and users to embrace new technologies. The article argues that any future market acceptance for artificial photosynthesis will depend upon the prevalence of nine factors, which create conducive environments; the lack of the conditions engenders environments where they will likely be rejected. The conditions are (i) strong institutional capacity; (ii) political commitment; (iii) favourable legal and regulatory frameworks; (iv) competitive installation and/or production costs; (v) mechanisms for information and feedback; (vi) access to financing; (vii) prolific community and/or individual ownership and use; (viii) participatory project siting; and (ix) recognition of externalities or positive public image. PMID:26052424

Anoxygenic photosynthesis controls oxygenic photosynthesis in a cyanobacterium from a sulfidic spring.

Science.gov (United States)

Klatt, Judith M; Al-Najjar, Mohammad A A; Yilmaz, Pelin; Lavik, Gaute; de Beer, Dirk; Polerecky, Lubos

2015-03-01

Before the Earth's complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39, in which this versatility is still conserved, and we show that the transition between the two photosynthetic modes follows a surprisingly simple kinetic regulation controlled by this organism's affinity for H2S. Specifically, oxygenic photosynthesis is performed in addition to anoxygenic photosynthesis only when H2S becomes limiting and its concentration decreases below a threshold that increases predictably with the available ambient light. The carbon-based growth rates during oxygenic and anoxygenic photosynthesis were similar. However, Pseudanabaena FS39 additionally assimilated NO3 (-) during anoxygenic photosynthesis. Thus, the transition between anoxygenic and oxygenic photosynthesis was accompanied by a shift of the C/N ratio of the total bulk biomass. These mechanisms offer new insights into the way in which, despite nutrient limitation in the oxic photic zone in the mid-Proterozoic oceans, versatile cyanobacteria might have promoted oxygenic photosynthesis and total primary productivity, a key step that enabled the complete oxygenation of our planet and the subsequent diversification of life. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Five Lectures on Photosynthesis

International Nuclear Information System (INIS)

Broda, E.

1979-01-01

These five lectures were held by E. Broda during the International Symposium on Alternative Energies, in September 1979. Lecture 1 – The Great Physicists and Photosynthesis; Lecture 2 – The Influence of Photosynthesis on the Biosphere. Past, Present and Future; Lecture 3 – The Origin of Photosynthesis; Lecture 4 – The Evolution from Photosynthetic Bacteria to Plants; Lecture 5 – Respiration and Photorespiration. (nowak)

High energy physics research. Final technical report, 1957--1994

International Nuclear Information System (INIS)

Williams, H.H.

1995-01-01

This is the final technical report to the Department of Energy on High Energy Physics at the University of Pennsylvania. It discusses research conducted in the following areas: neutrino astrophysics and cosmology; string theory; electroweak and collider physics; supergravity; cp violation and baryogenesis; particle cosmology; collider detector at Fermilab; the sudbury neutrino observatory; B-physics; particle physics in nuclei; and advanced electronics and detector development

High energy physics research. Final technical report, 1957--1994

Energy Technology Data Exchange (ETDEWEB)

Williams, H.H.

1995-10-01

This is the final technical report to the Department of Energy on High Energy Physics at the University of Pennsylvania. It discusses research conducted in the following areas: neutrino astrophysics and cosmology; string theory; electroweak and collider physics; supergravity; cp violation and baryogenesis; particle cosmology; collider detector at Fermilab; the sudbury neutrino observatory; B-physics; particle physics in nuclei; and advanced electronics and detector development.

Fruit photosynthesis in Satsuma mandarin.

Science.gov (United States)

Hiratsuka, Shin; Suzuki, Mayu; Nishimura, Hiroshi; Nada, Kazuyoshi

2015-12-01

To clarify detailed characteristics of fruit photosynthesis, possible gas exchange pathway and photosynthetic response to different environments were investigated in Satsuma mandarin (Citrus unshiu). About 300 mm(-2) stomata were present on fruit surface during young stages (∼10-30 mm diameter fruit) and each stoma increased in size until approximately 88 days after full bloom (DAFB), while the stomata collapsed steadily thereafter; more than 50% stomata deformed at 153 DAFB. The transpiration rate of the fruit appeared to match with stoma development and its intactness rather than the density. Gross photosynthetic rate of the rind increased gradually with increasing CO2 up to 500 ppm but decreased at higher concentrations, which may resemble C4 photosynthesis. In contrast, leaf photosynthesis increased constantly with CO2 increment. Although both fruit and leaf photosynthesis were accelerated by rising photosynthetic photon flux density (PPFD), fruit photosynthesis was greater under considerably lower PPFD from 13.5 to 68 μmolm(-2)s(-1). Thus, Satsuma mandarin fruit appears to incorporate CO2 through fully developed and non-collapsed stomata, and subject it to fruit photosynthesis, which may be characterized as intermediate status among C3, C4 and shade plant photosynthesis. The device of fruit photosynthesis may develop differently from its leaf to capture CO2 efficiently. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Teaching Photosynthesis with ELL Students

Science.gov (United States)

Piper, Susan; Shaw, Edward Lewis, Jr.

2010-01-01

Although the teaching of photosynthesis occurs yearly in elementary classrooms, one thing that makes it challenging is the inclusion of English language learners (ELLs). This article presents several activities for teaching and assessing of photosynthesis in a third grade classroom. The activities incorporate the photosynthesis content, teaching…

Technical approach to finalizing sensible soil cleanup levels at the Fernald Environmental Management Project

International Nuclear Information System (INIS)

Carr, D.; Hertel, B.; Jewett, M.; Janke, R.; Conner, B.

1996-01-01

The remedial strategy for addressing contaminated environmental media was recently finalized for the US Department of Energy's (DOE) Fernald Environmental Management Project (FEMP) following almost 10 years of detailed technical analysis. The FEMP represents one of the first major nuclear facilities to successfully complete the Remedial Investigation/Feasibility Study (RI/FS) phase of the environmental restoration process. A critical element of this success was the establishment of sensible cleanup levels for contaminated soil and groundwater both on and off the FEMP property. These cleanup levels were derived based upon a strict application of Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) regulations and guidance, coupled with positive input from the regulatory agencies and the local community regarding projected future land uses for the site. The approach for establishing the cleanup levels was based upon a Feasibility Study (FS) strategy that examined a bounding range of viable future land uses for the site. Within each land use, the cost and technical implications of a range of health-protective cleanup levels for the environmental media were analyzed. Technical considerations in driving these cleanup levels included: direct exposure routes to viable human receptors; cross- media impacts to air, surface water, and groundwater; technical practicality of attaining the levels; volume of affected media; impact to sensitive environmental receptors or ecosystems; and cost. This paper will discuss the technical approach used to support the finalization of the cleanup levels for the site. The final cleanup levels provide the last remaining significant piece to the puzzle of establishing a final site-wide remedial strategy for the FEMP, and positions the facility for the expedient completion of site-wide remedial activities

Audit of Wolf Creek Generating Station, Unit 1 technical specifications. Final technical evaluation report

International Nuclear Information System (INIS)

Stromberg, H.M.

1985-07-01

This document was prepared for the Nuclear Regulatory Commission (NRC) to assist them in determining whether the Wolf Creek Generating Station Unit 1 Technical Specifications (T/S), which govern plant systems configurations and operations, are in conformance with the assumptions of the Final Safety Analysis Report (FSAR) as amended, the requirements of the Safety Evaluation Report (SER) as supplemented, and the Comments and Responses to the Wolf Creek Technical Specification Draft Inspection Report. A comparative audit of the FSAR as amended, the SER as supplemented, and the Draft Inspection Report was performed with the Wolf Creek T/S. Several discrepancies were identified and subsequently resolved through discussions with the cognizant NRC reviewer, NRC staff reviewers and/or utility representatives. The Wolf Creek Generating Station Unit 1 T/S, to the extent reviewed, are in conformance with the FSAR, SER, and Draft Inspection Report

The Evolution of Photosynthesis

International Nuclear Information System (INIS)

Broda, E.

1976-01-01

This Review was written by Engelbert Broda, an Austrian Chemist and Physicist, on February the 10th 1976. The merits of the inductive and the deductive approach in tracing the pathways of evolution are discussed. Using the latter approach, it is concluded that photosynthesis followed fermentation as a method of obtaining energy-rich compounds, especially ATP. Photosynthesis probably arose by utilization of membranes for bioenergetic processes. Originally photosynthesis served photophosphorylation (ATP production), later reducing power was also made, either by open-ended, light-powered, electron flow or driven by ATP; ultimate electron donors were at first hydrogen or sulfur compounds, and later water, the last-named capability Was acquired by prokaryotic algae the earliest plants, similar to the recent blue-greens. When free oxygen entered the atmosphere for the first time, various forms of respiration (oxidative phosphorylation) became possible. Mechanistically, respiration evolved from photosynthesis (‘conversion hypotheses’). Prokaryotic algae are probably the ancestors of the chloroplasts in the eukaryotes, In the evolution of the eukaryotes, not much change in the basic processes of photosynthesis occurred.(author)

78 FR 12955 - Final Requirements, Definitions, and Selection Criteria-Native American Career and Technical...

Science.gov (United States)

2013-02-26

... career and technical education programs (20 U.S.C. 2326(e)). This notice does not preclude us from... DEPARTMENT OF EDUCATION 34 CFR Chapter IV [Docket ID ED-2012-OVAE-0053] Final Requirements, Definitions, and Selection Criteria--Native American Career and Technical Education Program (NACTEP) [Catalog...

Photosynthesis in Hydrogen-Dominated Atmospheres

Science.gov (United States)

Bains, William; Seager, Sara; Zsom, Andras

2014-01-01

The diversity of extrasolar planets discovered in the last decade shows that we should not be constrained to look for life in environments similar to early or present-day Earth. Super-Earth exoplanets are being discovered with increasing frequency, and some will be able to retain a stable, hydrogen-dominated atmosphere. We explore the possibilities for photosynthesis on a rocky planet with a thin H2-dominated atmosphere. If a rocky, H2-dominated planet harbors life, then that life is likely to convert atmospheric carbon into methane. Outgassing may also build an atmosphere in which methane is the principal carbon species. We describe the possible chemical routes for photosynthesis starting from methane and show that less energy and lower energy photons could drive CH4-based photosynthesis as compared with CO2-based photosynthesis. We find that a by-product biosignature gas is likely to be H2, which is not distinct from the hydrogen already present in the environment. Ammonia is a potential biosignature gas of hydrogenic photosynthesis that is unlikely to be generated abiologically. We suggest that the evolution of methane-based photosynthesis is at least as likely as the evolution of anoxygenic photosynthesis on Earth and may support the evolution of complex life. PMID:25411926

Photosynthesis in Hydrogen-Dominated Atmospheres

Directory of Open Access Journals (Sweden)

William Bains

2014-11-01

Full Text Available The diversity of extrasolar planets discovered in the last decade shows that we should not be constrained to look for life in environments similar to early or present-day Earth. Super-Earth exoplanets are being discovered with increasing frequency, and some will be able to retain a stable, hydrogen-dominated atmosphere. We explore the possibilities for photosynthesis on a rocky planet with a thin H2-dominated atmosphere. If a rocky, H2-dominated planet harbors life, then that life is likely to convert atmospheric carbon into methane. Outgassing may also build an atmosphere in which methane is the principal carbon species. We describe the possible chemical routes for photosynthesis starting from methane and show that less energy and lower energy photons could drive CH4-based photosynthesis as compared with CO2-based photosynthesis. We find that a by-product biosignature gas is likely to be H2, which is not distinct from the hydrogen already present in the environment. Ammonia is a potential biosignature gas of hydrogenic photosynthesis that is unlikely to be generated abiologically. We suggest that the evolution of methane-based photosynthesis is at least as likely as the evolution of anoxygenic photosynthesis on Earth and may support the evolution of complex life.

Technical planning activity: Final report

Energy Technology Data Exchange (ETDEWEB)

1987-01-01

In April 1985, the US Department of Energy's (DOE's) Office of Fusion Energy commissioned the Technical Planning Activity (TPA). The purpose of this activity was to develop a technical planning methodology and prepare technical plans in support of the strategic and policy framework of the Magnetic Fusion Program Plan issued by DOE in February 1985. Although this report represents the views of only the US magnetic fusion community, it is international in scope in the sense that the technical plans contained herein describe the full scope of the tasks that are prerequisites for the commercialization of fusion energy. The TPA has developed a well-structured methodology that includes detailed definitions of technical issues, definitions of program areas and elements, statements of research and development objectives, identification of key decision points and milestones, and descriptions of facility requirements.

Technical planning activity: Final report

International Nuclear Information System (INIS)

1987-01-01

In April 1985, the US Department of Energy's (DOE's) Office of Fusion Energy commissioned the Technical Planning Activity (TPA). The purpose of this activity was to develop a technical planning methodology and prepare technical plans in support of the strategic and policy framework of the Magnetic Fusion Program Plan issued by DOE in February 1985. Although this report represents the views of only the US magnetic fusion community, it is international in scope in the sense that the technical plans contained herein describe the full scope of the tasks that are prerequisites for the commercialization of fusion energy. The TPA has developed a well-structured methodology that includes detailed definitions of technical issues, definitions of program areas and elements, statements of research and development objectives, identification of key decision points and milestones, and descriptions of facility requirements

Technical area status report for low-level mixed waste final waste forms. Volume 1

Energy Technology Data Exchange (ETDEWEB)

Mayberry, J.L.; DeWitt, L.M. [Science Applications International Corp., Idaho Falls, ID (United States); Darnell, R. [EG and G Idaho, Inc., Idaho Falls, ID (United States)] [and others

1993-08-01

The Final Waste Forms (FWF) Technical Area Status Report (TASR) Working Group, the Vitrification Working Group (WG), and the Performance Standards Working Group were established as subgroups to the FWF Technical Support Group (TSG). The FWF TASR WG is comprised of technical representatives from most of the major DOE sites, the Nuclear Regulatory Commission (NRC), the EPA Office of Solid Waste, and the EPA`s Risk Reduction Engineering Laboratory (RREL). The primary activity of the FWF TASR Working Group was to investigate and report on the current status of FWFs for LLNM in this TASR. The FWF TASR Working Group determined the current status of the development of various waste forms described above by reviewing selected articles and technical reports, summarizing data, and establishing an initial set of FWF characteristics to be used in evaluating candidate FWFS; these characteristics are summarized in Section 2. After an initial review of available information, the FWF TASR Working Group chose to study the following groups of final waste forms: hydraulic cement, sulfur polymer cement, glass, ceramic, and organic binders. The organic binders included polyethylene, bitumen, vinyl ester styrene, epoxy, and urea formaldehyde. Section 3 provides a description of each final waste form. Based on the literature review, the gaps and deficiencies in information were summarized, and conclusions and recommendations were established. The information and data presented in this TASR are intended to assist the FWF Production and Assessment TSG in evaluating the Technical Task Plans (TTPs) submitted to DOE EM-50, and thus provide DOE with the necessary information for their FWF decision-making process. This FWF TASR will also assist the DOE and the MWIP in establishing the most acceptable final waste forms for the various LLMW streams stored at DOE facilities.

77 FR 30512 - Native American Career and Technical Education Program; Final Waivers and Extension of Project...

Science.gov (United States)

2012-05-23

... DEPARTMENT OF EDUCATION Native American Career and Technical Education Program; Final Waivers and... American Career and Technical Education Program Catalog of Federal Domestic Assistance (CFDA) Number: 84... and Technical Education Program (NACTEP), the Secretary waives 34 CFR 75.250 and 75.261(c)(2) in order...

"Type Ia Supernovae: Tools for Studying Dark Energy" Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Woosley, Stan [Lick Observatory, San Jose, CA (United States); Kasen, Dan [Univ. of California, Berkeley, CA (United States)

2017-05-10

Final technical report for project "Type Ia Supernovae: Tools for the Study of Dark Energy" awarded jointly to scientists at the University of California, Santa Cruz and Berkeley, for computer modeling, theory and data analysis relevant to the use of Type Ia supernovae as standard candles for cosmology.

PHOTOSYNTHESIS

Energy Technology Data Exchange (ETDEWEB)

Bryant, Donald A. [Pennsylvania State Univ., University Park, PA (United States)

2002-06-21

The Gordon Research Conference (GRC) on PHOTOSYNTHESIS was held at Roger Williams University, Bristol, RI. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

Key technical issues associated with a method of pulse compression. Final technical report

International Nuclear Information System (INIS)

Hunter, R.O. Jr.

1980-06-01

Key technical issues for angular multiplexing as a method of pulse compression in a 100 KJ KrF laser have been studied. Environmental issues studied include seismic vibrations man-made vibrations, air propagation, turbulence, and thermal gradient-induced density fluctuations. These studies have been incorporated in the design of mirror mounts and an alignment system, both of which are reported. A design study and performance analysis of the final amplifier have been undertaken. The pulse compression optical train has been designed and assessed as to its performance. Individual components are described and analytical relationships between the optical component size, surface quality, damage threshold and final focus properties are derived. The optical train primary aberrations are obtained and a method for aberration minimization is presented. Cost algorithms for the mirrors, mounts, and electrical hardware are integrated into a cost model to determine system costs as a function of pulse length, aperture size, and spot size

The Michigan high-level radioactive waste program: Final technical progress report

International Nuclear Information System (INIS)

1987-01-01

This report comprises the state of Michigan's final technical report on the location of a proposed high-level radioactive waste disposal site. Included are a list of Michigan's efforts to review the DOE proposal and a detailed report on the application of geographic information systems analysis techniques to the review process

Final Technical Report, Wind Generator Project (Ann Arbor)

Energy Technology Data Exchange (ETDEWEB)

Geisler, Nathan [City of Ann Arbor, MI (United States)

2017-03-20

A Final Technical Report (57 pages) describing educational exhibits and devices focused on wind energy, and related outreach activities and programs. Project partnership includes the City of Ann Arbor, MI and the Ann Arbor Hands-on Museum, along with additional sub-recipients, and U.S. Department of Energy/Office of Energy Efficiency and Renewable Energy (EERE). Report relays key milestones and sub-tasks as well as numerous graphics and images of five (5) transportable wind energy demonstration devices and five (5) wind energy exhibits designed and constructed between 2014 and 2016 for transport and use by the Ann Arbor Hands-on Museum.

Photosynthesis solutions to enhance productivity.

Science.gov (United States)

Foyer, Christine H; Ruban, Alexander V; Nixon, Peter J

2017-09-26

The concept that photosynthesis is a highly inefficient process in terms of conversion of light energy into biomass is embedded in the literature. It is only in the past decade that the processes limiting photosynthetic efficiency have been understood to an extent that allows a step change in our ability to manipulate light energy assimilation into carbon gain. We can therefore envisage that future increases in the grain yield potential of our major crops may depend largely on increasing the efficiency of photosynthesis. The papers in this issue provide new insights into the nature of current limitations on photosynthesis and identify new targets that can be used for crop improvement, together with information on the impacts of a changing environment on the productivity of photosynthesis on land and in our oceans.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'. © 2017 The Author(s).

Artificial Photosynthesis: Beyond Mimicking Nature

International Nuclear Information System (INIS)

Dau, Holger; Fujita, Etsuko; Sun, Licheng

2017-01-01

In this Editorial, Guest Editors Holger Dau, Etsuko Fujita, and Licheng Sun introduce the Special Issue of ChemSusChem on “Artificial Photosynthesis for Sustainable Fuels”. Here, they discuss the need for non-fossil based fuels, introduce both biological and artificial photosynthesis, and outline various important concepts in artificial photosynthesis, including molecular and solid-state catalysts for water oxidation and hydrogen evolution, catalytic CO 2 reduction, and photoelectrochemical systems.

Annual cycle of Scots pine photosynthesis

Directory of Open Access Journals (Sweden)

P. Hari

2017-12-01

Full Text Available Photosynthesis, i.e. the assimilation of atmospheric carbon to organic molecules with the help of solar energy, is a fundamental and well-understood process. Here, we connect theoretically the fundamental concepts affecting C3 photosynthesis with the main environmental drivers (ambient temperature and solar light intensity, using six axioms based on physiological and physical knowledge, and yield straightforward and simple mathematical equations. The light and carbon reactions in photosynthesis are based on the coherent operation of the photosynthetic machinery, which is formed of a complicated chain of enzymes, membrane pumps and pigments. A powerful biochemical regulation system has emerged through evolution to match photosynthesis with the annual cycle of solar light and temperature. The action of the biochemical regulation system generates the annual cycle of photosynthesis and emergent properties, the state of the photosynthetic machinery and the efficiency of photosynthesis. The state and the efficiency of the photosynthetic machinery is dynamically changing due to biosynthesis and decomposition of the molecules. The mathematical analysis of the system, defined by the very fundamental concepts and axioms, resulted in exact predictions of the behaviour of daily and annual patterns in photosynthesis. We tested the predictions with extensive field measurements of Scots pine (Pinus sylvestris L. photosynthesis on a branch scale in northern Finland. Our theory gained strong support through rigorous testing.

Annual cycle of Scots pine photosynthesis

Science.gov (United States)

Hari, Pertti; Kerminen, Veli-Matti; Kulmala, Liisa; Kulmala, Markku; Noe, Steffen; Petäjä, Tuukka; Vanhatalo, Anni; Bäck, Jaana

2017-12-01

Photosynthesis, i.e. the assimilation of atmospheric carbon to organic molecules with the help of solar energy, is a fundamental and well-understood process. Here, we connect theoretically the fundamental concepts affecting C3 photosynthesis with the main environmental drivers (ambient temperature and solar light intensity), using six axioms based on physiological and physical knowledge, and yield straightforward and simple mathematical equations. The light and carbon reactions in photosynthesis are based on the coherent operation of the photosynthetic machinery, which is formed of a complicated chain of enzymes, membrane pumps and pigments. A powerful biochemical regulation system has emerged through evolution to match photosynthesis with the annual cycle of solar light and temperature. The action of the biochemical regulation system generates the annual cycle of photosynthesis and emergent properties, the state of the photosynthetic machinery and the efficiency of photosynthesis. The state and the efficiency of the photosynthetic machinery is dynamically changing due to biosynthesis and decomposition of the molecules. The mathematical analysis of the system, defined by the very fundamental concepts and axioms, resulted in exact predictions of the behaviour of daily and annual patterns in photosynthesis. We tested the predictions with extensive field measurements of Scots pine (Pinus sylvestris L.) photosynthesis on a branch scale in northern Finland. Our theory gained strong support through rigorous testing.

Final Scientific/Technical Report – BISfuel EFRC

Energy Technology Data Exchange (ETDEWEB)

Gust, Devens

2015-07-13

The vast majority of the country’s energy needs are met with fossil fuels in the form of natural gas, coal and oil. The use of these fossil fuels contributes to climate change, the unequal distribution of fossil fuel deposits in the earth leads to geopolitical and economic problems, and eventually, fossil fuels will be exhausted. Thus, a renewable, widely distributed, environmentally benign, and inexpensive substitute large enough to meet the needs of society is required. Solar energy meets these criteria. Solar energy may be converted to electricity by photovoltaics, but the need for a continuous energy supply and high-density energy requirements for transportation necessitate technology for storage of energy from sunlight in a fuel. Cost-effective technologies for solar fuel production do not exist, prompting the need for new fundamental science. Fuel production requires not only energy, but also a source of electrons and precursor materials suitable for reduction to useful fuels. Given the immense magnitude of the human energy requirement, the most reasonable source of electrons is water oxidation, and suitable precursor materials are hydrogen ions (for hydrogen gas production) and carbon dioxide (for production of reduced carbon fuels such as methane or methanol). Natural photosynthesis is the only proven “technology” for solar fuel production. It harvests solar energy on a magnitude much larger than that necessary to fill human needs, and has done so for billions of years, creating fossil fuels along the way. BISfuel has approached the design of a complete system for solar water oxidation and hydrogen production by applying the fundamental principles of photosynthesis to the construction of synthetic components and their incorporation into an operational unit. In this artificial photosynthetic approach, the functional blueprint of photosynthesis is followed using non-biological materials. BISfuel brought together a group of investigators from the

Photosynthesis in high definition

Science.gov (United States)

Hilton, Timothy W.

2018-01-01

Photosynthesis is the foundation for almost all known life, but quantifying it at scales above a single plant is difficult. A new satellite illuminates plants' molecular machinery at much-improved spatial resolution, taking us one step closer to combined `inside-outside' insights into large-scale photosynthesis.

Iowa Hill Pumped Storage Project Investigations - Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Hanson, David [Sacramento Municipal Unitlity District, Sacramento, CA (United States)

2016-07-01

This Final Technical Report is a summary of the activities and outcome of the Department of Energy (DOE) Assistance Agreement DE-EE0005414 with the Sacramento Municipal Utility District (SMUD). The Assistance Agreement was created in 2012 to support investigations into the Iowa Hill Pumped-storage Project (Project), a new development that would add an additional 400 MW of capacity to SMUD’s existing 688MW Upper American River Hydroelectric Project (UARP) in the Sierra Nevada mountains east of Sacramento, California.

Admiralty Inlet Pilot Tidal Project Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Collar, Craig [Public Utility District No. 1 of Snohomish County, Everett, WA (United States)

2015-09-14

This document represents the final report for the Admiralty Inlet Pilot Tidal Project, located in Puget Sound, Washington, United States. The Project purpose was to license, permit, and install a grid-connected deep-water tidal turbine array (two turbines) to be used as a platform to gather operational and environmental data on tidal energy generation. The data could then be used to better inform the viability of commercial tidal energy generation from technical, economic, social, and environmental standpoints. This data would serve as a critical step towards the responsible advancement of commercial scale tidal energy in the United States and around the world. In late 2014, Project activities were discontinued due to escalating costs, and the DOE award was terminated in early 2015. Permitting, licensing, and engineering design activities were completed under this award. Final design, deployment, operation, and monitoring were not completed. This report discusses the results and accomplishments achieved under the subject award.

77 FR 30514 - Native Hawaiian Career and Technical Education Program; Final Waiver and Extension of Project Period

Science.gov (United States)

2012-05-23

... DEPARTMENT OF EDUCATION Native Hawaiian Career and Technical Education Program; Final Waiver and... Career and Technical Education Program Catalog of Federal Domestic Assistance (CFDA) Number: 84.259A... Technical Education Program (NHCTEP), the Secretary hereby waives 34 CFR 75.261(c)(2) in order to extend the...

Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Schuur, Edward [Northern Arizona Univ., Flagstaff, AZ (United States); Luo, Yiqi [Univ. of Oklahoma, Norman, OK (United States)

2016-12-01

This final grant report is a continuation of the final grant report submitted for DE-SC0006982 as the Principle Investigator (Schuur) relocated from the University of Florida to Northern Arizona University. This report summarizes the original project goals, as well as includes new project activities that were completed in the final period of the project.

Elements Required for an Efficient NADP-Malic Enzyme Type C4 Photosynthesis1[C][W][OPEN

Science.gov (United States)

Wang, Yu; Long, Stephen P.; Zhu, Xin-Guang

2014-01-01

C4 photosynthesis has higher light, nitrogen, and water use efficiencies than C3 photosynthesis. Although the basic anatomical, cellular, and biochemical features of C4 photosynthesis are well understood, the quantitative significance of each element of C4 photosynthesis to the high photosynthetic efficiency are not well defined. Here, we addressed this question by developing and using a systems model of C4 photosynthesis, which includes not only the Calvin-Benson cycle, starch synthesis, sucrose synthesis, C4 shuttle, and CO2 leakage, but also photorespiration and metabolite transport between the bundle sheath cells and mesophyll cells. The model effectively simulated the CO2 uptake rates, and the changes of metabolite concentrations under varied CO2 and light levels. Analyses show that triose phosphate transport and CO2 leakage can help maintain a high photosynthetic rate by balancing ATP and NADPH amounts in bundle sheath cells and mesophyll cells. Finally, we used the model to define the optimal enzyme properties and a blueprint for C4 engineering. As such, this model provides a theoretical framework for guiding C4 engineering and studying C4 photosynthesis in general. PMID:24521879

Characterization of the radon source in North-Central Florida. Final report part 1 -- Final project report; Final report part 2 -- Technical report

International Nuclear Information System (INIS)

1997-01-01

This report contains two separate parts: Characterization of the Radon Source in North-Central Florida (final report part 1 -- final project report); and Characterization of the Radon Source in North-Central Florida (technical report). The objectives were to characterize the radon 222 source in a region having a demonstrated elevated indoor radon potential and having geology, lithology, and climate that are different from those in other regions of the U.S. where radon is being studied. Radon availability and transport in this region were described. Approaches for predicting the radon potential of lands in this region were developed

Dynamic photosynthesis in different environmental conditions.

Science.gov (United States)

Kaiser, Elias; Morales, Alejandro; Harbinson, Jeremy; Kromdijk, Johannes; Heuvelink, Ep; Marcelis, Leo F M

2015-05-01

Incident irradiance on plant leaves often fluctuates, causing dynamic photosynthesis. Whereas steady-state photosynthetic responses to environmental factors have been extensively studied, knowledge of dynamic modulation of photosynthesis remains scarce and scattered. This review addresses this discrepancy by summarizing available data and identifying the research questions necessary to advance our understanding of interactions between environmental factors and dynamic behaviour of photosynthesis using a mechanistic framework. Firstly, dynamic photosynthesis is separated into sub-processes related to proton and electron transport, non-photochemical quenching, control of metabolite flux through the Calvin cycle (activation states of Rubisco and RuBP regeneration, and post-illumination metabolite turnover), and control of CO₂ supply to Rubisco (stomatal and mesophyll conductance changes). Secondly, the modulation of dynamic photosynthesis and its sub-processes by environmental factors is described. Increases in ambient CO₂ concentration and temperature (up to ~35°C) enhance rates of photosynthetic induction and decrease its loss, facilitating more efficient dynamic photosynthesis. Depending on the sensitivity of stomatal conductance, dynamic photosynthesis may additionally be modulated by air humidity. Major knowledge gaps exist regarding environmental modulation of loss of photosynthetic induction, dynamic changes in mesophyll conductance, and the extent of limitations imposed by stomatal conductance for different species and environmental conditions. The study of mutants or genetic transformants for specific processes under various environmental conditions could provide significant progress in understanding the control of dynamic photosynthesis. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Clean Energy Works Oregon Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Jacob, Andria [City of Portland; Cyr, Shirley [Clean Energy Works

2013-12-31

In April 2010, the City of Portland received a $20 million award from the U.S. Department of Energy, as part of the Energy Efficiency and Conservation Block Grant program. This award was appropriated under the American Recovery and Reinvestment Act (ARRA), passed by President Obama in 2009. DOE’s program became known as the Better Buildings Neighborhood Program (BBNP). The BBNP grant objectives directed the City of Portland Bureau of Planning and Sustainability (BPS) as the primary grantee to expand the BPS-led pilot program, Clean Energy Works Portland, into Clean Energy Works Oregon (CEWO), with the mission to deliver thousands of home energy retrofits, create jobs, save energy and reduce carbon dioxide emissions.The Final Technical Report explores the successes and lessons learned from the first 3 years of program implementation.

Energy Impact Illinois - Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Olson, Daniel [Senior Energy Efficiency Planner; Plagman, Emily [Senior Energy Planner; Silberhorn, Joey-Lin [Energy Efficiency Program Assistant

2014-02-18

Energy Impact Illinois (EI2) is an alliance of government organizations, nonprofits, and regional utility companies led by the Chicago Metropolitan Agency for Planning (CMAP) that is dedicated to helping communities in the Chicago metropolitan area become more energy efficient. Originally organized as the Chicago Region Retrofit Ramp-Up (CR3), EI2 became part of the nationwide Better Buildings Neighborhood Program (BBNP) in May 2010 after receiving a $25 million award from the U.S. Department of Energy (DOE) authorized through the American Recovery and Reinvestment Act of 2009 (ARRA). The program’s primary goal was to fund initiatives that mitigate barriers to energy efficiency retrofitting activities across residential, multifamily, and commercial building sectors in the seven-county CMAP region and to help to build a sustainable energy efficiency marketplace. The EI2 Final Technical Report provides a detailed review of the strategies, implementation methods, challenges, lessons learned, and final results of the EI2 program during the initial grant period from 2010-2013. During the program period, EI2 successfully increased direct retrofit activity in the region and was able to make a broader impact on the energy efficiency market in the Chicago region. As the period of performance for the initial grant comes to an end, EI2’s legacy raises the bar for the region in terms of helping homeowners and building owners to take action on the continually complex issue of energy efficiency.

Carotenoids and Photosynthesis.

Science.gov (United States)

Hashimoto, Hideki; Uragami, Chiasa; Cogdell, Richard J

2016-01-01

Carotenoids are ubiquitous and essential pigments in photosynthesis. They absorb in the blue-green region of the solar spectrum and transfer the absorbed energy to (bacterio-)chlorophylls, and so expand the wavelength range of light that is able to drive photosynthesis. This is an example of singlet-singlet energy transfer, and so carotenoids serve to enhance the overall efficiency of photosynthetic light reactions. Carotenoids also act to protect photosynthetic organisms from the harmful effects of excess exposure to light. Triplet-triplet energy transfer from chlorophylls to carotenoids plays a key role in this photoprotective reaction. In the light-harvesting pigment-protein complexes from purple photosynthetic bacteria and chlorophytes, carotenoids have an additional role of structural stabilization of those complexes. In this article we review what is currently known about how carotenoids discharge these functions. The molecular architecture of photosynthetic systems will be outlined first to provide a basis from which to describe carotenoid photochemistry, which underlies most of their important functions in photosynthesis.

Predicting photosynthesis and transpiration responses to ozone: decoupling modeled photosynthesis and stomatal conductance

Directory of Open Access Journals (Sweden)

D. Lombardozzi

2012-08-01

Full Text Available Plants exchange greenhouse gases carbon dioxide and water with the atmosphere through the processes of photosynthesis and transpiration, making them essential in climate regulation. Carbon dioxide and water exchange are typically coupled through the control of stomatal conductance, and the parameterization in many models often predict conductance based on photosynthesis values. Some environmental conditions, like exposure to high ozone (O₃ concentrations, alter photosynthesis independent of stomatal conductance, so models that couple these processes cannot accurately predict both. The goals of this study were to test direct and indirect photosynthesis and stomatal conductance modifications based on O₃ damage to tulip poplar (Liriodendron tulipifera in a coupled Farquhar/Ball-Berry model. The same modifications were then tested in the Community Land Model (CLM to determine the impacts on gross primary productivity (GPP and transpiration at a constant O₃ concentration of 100 parts per billion (ppb. Modifying the V_cmax parameter and directly modifying stomatal conductance best predicts photosynthesis and stomatal conductance responses to chronic O₃ over a range of environmental conditions. On a global scale, directly modifying conductance reduces the effect of O₃ on both transpiration and GPP compared to indirectly modifying conductance, particularly in the tropics. The results of this study suggest that independently modifying stomatal conductance can improve the ability of models to predict hydrologic cycling, and therefore improve future climate predictions.

Final Technical Report for DE-FG02-98ER45737

Energy Technology Data Exchange (ETDEWEB)

Ade, Harald W.

2018-04-24

Final Technical Report For DOE Grant No. DE-FG02-98ER45737 Development of a Scanning Transmission X-Ray Microscope Polymer Thin Films and Self Assembled Monolayers: Pattern Formation and Surface Interactions NEXAFS Microscopy and Resonant Scattering of Polymeric Materials Organic Heterojunction Devices: Structure, Composition, and Performance at <20 nm Resolution Fundamental Science of High Open Circuit Voltage Excitonic Solar Cells Control of Interface- and Mesoscopic Structure in High Performance Organic Solar Cells: Towards a Predictive Device Paradigm

Can miscanthus C4 photosynthesis compete with festulolium C3 photosynthesis in a temperate climate?

DEFF Research Database (Denmark)

Jiao, Xiurong; Kørup, Kirsten; Andersen, Mathias Neumann

2017-01-01

Miscanthus, a perennial grass with C4 photosynthesis, is regarded as a promising energy crop due to its high biomass productivity. Compared with other C4 species, most miscanthus genotypes have high cold tolerances at 14 °C. However, in temperate climates, temperatures below 14 °C are common...... at each temperature level and still maintained photosynthesis after growing for a longer period at 6/4 °C. Only two of five measured miscanthus genotypes increased photosynthesis immediately after the temperature was raised again. The photosynthetic capacity of festulolium was significantly higher at 10...

Summary report of the final technical meeting on 'International Reactor Dosimetry File: IRDF-2002'

International Nuclear Information System (INIS)

Griffin, Patrick J.; Paviotti-Corcuera, R.

2003-10-01

Presentations, recommendations and conclusions of the Final Technical Meeting on 'International Reactor Dosimetry File: IRDF-2002' are summarized in this report. The main aims of this meeting were to discuss scientific and technical matters related to reactor dosimetry and to assign responsibilities for the preparation of the final version of the IRDF- 2002 library and the associated TECDOC. Tasks were assigned and deadlines were agreed. Participants emphasized that accurate and complete nuclear data for reactor dosimetry are essential to improve the assessment accuracies for reactor pressure vessel service lifetimes in nuclear power plants, as well as for other neutron metrology applications such as boron neutron capture therapy, therapeutic use of medical isotopes, nuclear physics measurements, and reactor safety applications. (author)

Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Eggeman, Tim [ZeaChem Inc., Lakewood, CO (United States); O' Neill, Brian [ZeaChem Inc., Lakewood, CO (United States)

2016-08-17

ZeaChem Inc. and US DOE successfully demonstrated the ZeaChem process for producing sugars and ethanol from high-impact biomass feedstocks. The project was executed over a 5-year period under a $31.25 million cooperative agreement (80:20 Federal:ZeaChem cost share). The project was managed by dividing it into three budget periods. Activities during Budget Period 1 were limited to planning, permitting, and other pre-construction planning. Budget Period 2 activities included engineering, procurement, construction, commissioning, start-up and initial operations through the Independent Engineer Test Runs. The scope of construction was limited to the Chem Frac and Hydrogenolysis units, as the Core Facility was already in place. Construction was complete in December 2012, and the first cellulosic ethanol was produced in February 2013. Additional operational test runs were conducted during Budget Period 3 (completed June 2015) using hybrid poplar, corn stover, and wheat straw feedstocks, resulting in the production of cellulosic ethanol and various other biorefinery intermediates. The research adds to the understanding of the Chem Frac and Hydrogenolysis technologies in that the technical performance of each unit was measured, and the resulting data and operational experience can be used as the basis for engineering designs, thus mitigating risks for deployment in future commercial facilities. The Chem Frac unit was initially designed to be operated as two-stage dilute acid hydrolysis, with first stage conditions selected to remove the hemicellulose fraction of the feedstock, and the second stage conditions selected to remove the cellulose fraction. While the Chem Frac unit met or exceeded the design capacity of 10 ton(dry)/day, the technical effectiveness of the Chem Frac unit was below expectations in its initial two-stage dilute acid configuration. The sugars yields were low, the sugars were dilute, and the sugars had poor fermentability caused by excessive inhibitors

Photosynthesis research in the USSR

Energy Technology Data Exchange (ETDEWEB)

Hall, D.O.

1979-09-27

Current research programs in photosynthesis in the USSR are described. Some of the programs include: (1) research on hydrogenases; (2) computer facilities (3) photochemical reduction of low potential compounds; (4) hydrogen-producing systems using model pigment systems; (5) stabilization of chloroplast membranes; (6) construction of fuel cells using immobilized enzymes; (7) carbon, hydrogen, and nitrogen metabolism of photosynthetic bacteria; (8) methane producing bacteria; (9) growth of photosynthetic bacteria under dark and light conditions; (10) efficiency of photosynthesis and plant productivity; (11) biomass as a future source of energy; (12) mycology; (13) isolation of photosystems; and (14) factors limiting photosynthesis in the leaf. (DC)

DE-FG02-04ER63746 FinalTechnicalReport

Energy Technology Data Exchange (ETDEWEB)

Lidstrom, M.E.

2009-09-05

This is the final technical report for a project involving the study of stress response systems in the radiation-resistant bacterium, Deinococcus radiodurans. Three stresses of importance for a mixed waste treatment strain were studied, heat shock, solvent shock, and phosphate starvation. In each case, specific genes involved in the ability to survive the stress were identified using a systems biology approach, and analysis of mutants was used to understand mechanisms. This study has led to increased understanding of the ways in which a potential treatment strain could be manipulated to survive multiple stresses for treatment of mixed wastes.

Physiological and Environmental Aspects of Photosynthesis

OpenAIRE

Ricardo Alfredo Kluge; Universidade de São Paulo; Jaqueline V. Tezotto-Uliana; Universidade de São Paulo; Paula P. M. da Silva; Universidade de São Paulo

2015-01-01

Undoubtedly, photosynthesis is one of the most important process for the life planet maintenance. The sun releases radiant energy that is able to boost the photosynthetic apparatus of the plants, which produce carbohydrates that will be used in the respiration. Among the most important reactions of photosynthesis is the release of oxygen, essential for respiration, which happens in photosystem II. The products generated in the first phase of photosynthesis or photochemical phase (ATP and NADP...

Mathematics Intensive Summer Session (MISS). Final technical report

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-11-01

This final technical report appears in two parts: the report for the 1995 summer MISS program and the report for the 1996 summer MISS program. Copies of the US Department of Energy Pre-Freshman Enrichment Program 1995 Entry Form and 1996 Entry Form completed by all participants were sent to the Oak Ridge Institute for Science and Education in the fall of 1995 and 1996 respectively. Those forms are on file should they be needed. Attached also is a copy of the Summary of ideas for panel discussions, problem-solving sessions, or small group discussions presented at the Department of Energy Oak Ridge Institute for Science and Education Pre-Freshman Enrichment Program Project Directors Meeting held in San Antonio, TX, November 12--14, 1995.

Microclimate, canopy structure and photosynthesis in canopies of three contrasting temperate forage grasses. III. Canopy photosynthesis, individual leaf photosynthesis and the distribution of current assimilate

Energy Technology Data Exchange (ETDEWEB)

Sheehy, J E

1977-01-01

The rates of canopy and individual leaf photosynthesis and /sup 14/C distribution for three temperate forage grasses Lolium perenne cv. S24, L. perenne cv. Reveille and Festuca arundinacea cv. S170 were determined in the field during a summer growth period. Canopy photosynthesis declined as the growth period progressed, reflecting a decline in the photosynthetic capacity of successive youngest fully expanded leaves. The decline in the maximum photosynthetic capacity of the canopies was correlated with a decline in their quantum efficiencies at low irradiance. Changes in canopy structure resulted in changes in canopy net photosynthesis and dark respiration. No clear relationships between changes in the environment and changes in canopy net photosynthesis and dark respiration were established. The relative distributions of /sup 14/C in the shoots of the varieties gave a good indication of the amount of dry matter per ground area in the varieties. 21 references, 4 figures, 1 table.

Technical and economic assessment of solar hybrid repowering. Final report

Energy Technology Data Exchange (ETDEWEB)

None

1978-09-01

Public Service Company of New Mexico (PNM) has performed a Technical and Economic Assessment of Solar Hybrid Repowering under funding by the Department of Energy (DOE), the Electric Power Research Institute (EPRI), Western Energy Supply and Transmission (WEST) Associates, and a number of southwestern utilities. Solar hybrid repowering involves placement of solar hardware adjacent to and connected to existing gas- and oil-fueled electric generation units to displace some of or all the fossil fuel normally used during daylight hours. The subject study assesses the technical economic viability of the solar hybrid repowering concept within the southwestern United States and the PNM system. This document is a final report on the study and its results. The study was divided into the six primary tasks to allow a systematic investigation of the concept: (1) market survey and cost/benefit analysis, (2) study unit selection, (3) conceptual design and cost estimates, (4) unit economic analysis, (5) program planning, future phases, and (6) program management. Reeves Station No. 2 at Albuquerque, New Mexico, was selected for repowering with a design goal of 50 percent (25 MWe). The solar system design is based on the 10 MW solar central receiver pilot plant preliminary design for Barstow, California. SAN--1608-4-2 contains the technical drawings. (WHK)

Potential photosynthesis of crop surfaces.

NARCIS (Netherlands)

Wit, de C.T.

1959-01-01

A formula for calculating the potential photosynthesis of a closed crop surface is proposed, assuming that the leaves of the crop are not arranged in any definite direction. In the Netherlands, values for potential photosynthesis vary from 290 kg. CH2O/ha./day in June to 50 kg./ha./day in December.

University of Maryland component of the Center for Multiscale Plasma Dynamics: Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Dorland, William [University of Maryland

2014-11-18

The Center for Multiscale Plasma Dynamics (CMPD) was a five-year Fusion Science Center. The University of Maryland (UMD) and UCLA were the host universities. This final technical report describes the physics results from the UMD CMPD.

Leaf absorbance and photosynthesis

Science.gov (United States)

Schurer, Kees

1994-01-01

The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Bohdan W. Oppenheim; Rudolf Marloth

2007-10-26

Executive Summary The document contains Final Technical Report on the Industrial Assessment Center Program at Loyola Marymount University in Los Angeles, covering the contract period of 9/1/2002 to 11/30/2006, under the contract DE-FC36-02GO 12073. The Report describes six required program tasks, as follows: TASK 1 is a summary of the assessments performed over the life of the award: 77 assessments were performed, 595 AR were recommended, covering a very broad range of manufacturing plants. TASK 2 is a description of the efforts to promote and increase the adoption of assessment recommendations and employ innovative methods to assist in accomplishing these goals. The LMU IAC has been very successful in accomplishing the program goals, including implemented savings of $5,141,895 in energy, $10,045,411 in productivity and $30,719 in waste, for a total of $15,218,025. This represents 44% of the recommended savings of $34,896,392. TASK 3 is a description of the efforts promoting the IAC Program and enhancing recruitment efforts for new clients and expanded geographic coverage. LMU IAC has been very successful recruiting new clients covering Southern California. Every year, the intended number of clients was recruited. TASK 4 describes the educational opportunities, training, and other related activities for IAC students. A total of 38 students graduated from the program, including 2-3 graduate students every semester, and the remainder undergraduate students, mostly from the Mechanical Engineering Department. The students received formal weekly training in energy (75%) and productivity (25). All students underwent extensive safety training. All students praised the IAC experience very highly. TASK 5 describes the coordination and integration of the Center activities with other Center and IAC Program activities, and DOE programs. LMU IAC worked closely with MIT, and SDSU IAC and SFSU IAC, and enthusiastically supported the SEN activities. TASK 6 describes other tasks

Could photosynthesis function on Proxima Centauri b?

Science.gov (United States)

Ritchie, Raymond J.; Larkum, Anthony W. D.; Ribas, Ignasi

2018-04-01

Could oxygenic and/or anoxygenic photosynthesis exist on planet Proxima Centauri b? Proxima Centauri (spectral type - M5.5 V, 3050 K) is a red dwarf, whereas the Sun is type G2 V (5780 K). The light regimes on Earth and Proxima Centauri b are compared with estimates of the planet's suitability for Chlorophyll a (Chl a) and Chl d-based oxygenic photosynthesis and for bacteriochlorophyll (BChl)-based anoxygenic photosynthesis. Proxima Centauri b has low irradiance in the oxygenic photosynthesis range (400-749 nm: 64-132 µmol quanta m-2 s-1). Much larger amounts of light would be available for BChl-based anoxygenic photosynthesis (350-1100 nm: 724-1538 µmol quanta m-2 s-1). We estimated primary production under these light regimes. We used the oxygenic algae Synechocystis PCC6803, Prochlorothrix hollandica, Acaryochloris marina, Chlorella vulgaris, Rhodomonas sp. and Phaeodactylum tricornutum and the anoxygenic photosynthetic bacteria Rhodopseudomonas palustris (BChl a), Afifella marina (BChl a), Thermochromatium tepidum (BChl a), Chlorobaculum tepidum (BChl a + c) and Blastochloris viridis (BChl b) as representative photosynthetic organisms. Proxima Centauri b has only ~3% of the PAR (400-700 nm) of Earth irradiance, but we found that potential gross photosynthesis (P g) on Proxima Centauri b could be surprisingly high (oxygenic photosynthesis: earth ~0.8 gC m-2 h-1 Proxima Centauri b ~0.14 gC m-2 h-1). The proportion of PAR irradiance useable by oxygenic photosynthetic organisms (the sum of Blue + Red irradiance) is similar for the Earth and Proxima Centauri b. The oxygenic photic zone would be only ~10 m deep in water compared with ~200 m on Earth. The P g of an anoxic Earth (gC m-2 h-1) is ~0.34-0.59 (land) and could be as high as ~0.29-0.44 on Proxima Centauri b. 1 m of water does not affect oxygenic or anoxygenic photosynthesis on Earth, but on Proxima Centauri b oxygenic P g is reduced by ~50%. Effective elimination of near IR limits P g by photosynthetic

Estimating phytoplankton photosynthesis by active fluorescence

Energy Technology Data Exchange (ETDEWEB)

Falkowski, P.G.; Kolber, Z.

1992-01-01

Photosynthesis can be described by target theory, At low photon flux densities, photosynthesis is a linear function of irradiance (I), The number of reaction centers (n), their effective absorption capture cross section {sigma}, and a quantum yield {phi}. As photosynthesis becomes increasingly light saturated, an increased fraction of reaction centers close. At light saturation the maximum photosynthetic rate is given as the product of the number of reaction centers (n) and their maximum electron transport rate (I/{tau}). Using active fluorometry it is possible to measure non-destructively and in real time the fraction of open or closed reaction centers under ambient irradiance conditions in situ, as well as {sigma} and {phi} {tau} can be readily, calculated from knowledge of the light saturation parameter, I{sub k} (which can be deduced by in situ by active fluorescence measurements) and {sigma}. We built a pump and probe fluorometer, which is interfaced with a CTD. The instrument measures the fluorescence yield of a weak probe flash preceding (f{sub 0}) and succeeding (f{sub 0}) a saturating pump flash. Profiles of the these fluorescence yields are used to derive the instantaneous rate of gross photosynthesis in natural phytoplankton communities without any incubation. Correlations with short-term simulated in situ radiocarbon measurements are extremely high. The average slope between photosynthesis derived from fluorescence and that measured by radiocarbon is 1.15 and corresponds to the average photosynthetic quotient. The intercept is about 15% of the maximum radiocarbon uptake and corresponds to the average net community respiration. Profiles of photosynthesis and sections showing the variability in its composite parameters reveal a significant effect of nutrient availability on biomass specific rates of photosynthesis in the ocean.

Estimating phytoplankton photosynthesis by active fluorescence

Energy Technology Data Exchange (ETDEWEB)

Falkowski, P.G.; Kolber, Z.

1992-10-01

Photosynthesis can be described by target theory, At low photon flux densities, photosynthesis is a linear function of irradiance (I), The number of reaction centers (n), their effective absorption capture cross section {sigma}, and a quantum yield {phi}. As photosynthesis becomes increasingly light saturated, an increased fraction of reaction centers close. At light saturation the maximum photosynthetic rate is given as the product of the number of reaction centers (n) and their maximum electron transport rate (I/{tau}). Using active fluorometry it is possible to measure non-destructively and in real time the fraction of open or closed reaction centers under ambient irradiance conditions in situ, as well as {sigma} and {phi} {tau} can be readily, calculated from knowledge of the light saturation parameter, I{sub k} (which can be deduced by in situ by active fluorescence measurements) and {sigma}. We built a pump and probe fluorometer, which is interfaced with a CTD. The instrument measures the fluorescence yield of a weak probe flash preceding (f{sub 0}) and succeeding (f{sub 0}) a saturating pump flash. Profiles of the these fluorescence yields are used to derive the instantaneous rate of gross photosynthesis in natural phytoplankton communities without any incubation. Correlations with short-term simulated in situ radiocarbon measurements are extremely high. The average slope between photosynthesis derived from fluorescence and that measured by radiocarbon is 1.15 and corresponds to the average photosynthetic quotient. The intercept is about 15% of the maximum radiocarbon uptake and corresponds to the average net community respiration. Profiles of photosynthesis and sections showing the variability in its composite parameters reveal a significant effect of nutrient availability on biomass specific rates of photosynthesis in the ocean.

Cadmium against higher plant photosynthesis - a variety of effects and where do they possibly come from?

International Nuclear Information System (INIS)

Krupa, Z.

1999-01-01

The complexity of in vivo toxic effects of Cd on higher plants makes almost impossible an accurate distinction between direct and indirect mechanisms of its action on the photosynthetic apparatus. We, therefore, postulate that multiple Cd effects on plant physiological and metabolic processes may finally be focused on photosynthesis. This would also explain the phenomenon that only a small fraction of Cd entering chloroplasts may cause such disastrous changes in their structure and function. In return, the inhibition of photosynthesis affects numerous metabolic pathways dependent on the primary carbon metabolism. (orig.)

Photosynthesis energy factory: analysis, synthesis, and demonstration. Final report

Energy Technology Data Exchange (ETDEWEB)

1978-11-01

This quantitative assessment of the potential of a combined dry-land Energy Plantation, wood-fired power plant, and algae wastewater treatment system demonstrates the cost-effectiveness of recycling certain by-products and effluents from one subsystem to another. Designed to produce algae up to the limit of the amount of carbon in municipal wastewater, the algae pond provides a positive cash credit, resulting mainly from the wastewater treatment credit, which may be used to reduce the cost of the Photosynthesis Energy Factory (PEF)-generated electricity. The algae pond also produces fertilizer, which reduces the cost of the biomass produced on the Energy Plantation, and some gas. The cost of electricity was as low as 35 mills per kilowatt-hour for a typical municipally-owned PEF consisting of a 65-MWe power plant, a 144-acre algae pond, and a 33,000-acre Energy Plantation. Using only conventional or near-term technology, the most cost-effective algae pond for a PEF is the carbon-limited secondary treatment system. This system does not recycle CO/sub 2/ from the flue gas. Analysis of the Energy Plantation subsystem at 15 sites revealed that plantations of 24,000 to 36,000 acres produce biomass at the lowest cost per ton. The following sites are recommended for more detailed evaluation as potential demonstration sites: Pensacola, Florida; Jamestown, New York; Knoxville, Tennessee; Martinsville, Virginia, and Greenwood, South Carolina. A major possible extension of the PEF concept is to include the possibility for irrigation.

Evaluation of Routine Atmospheric Sounding Measurements using Unmanned Systems (ERASMUS): Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

de Boer, Gijs [Univ. of Colorado, Boulder, CO (United States); Lawrence, Dale [Univ. of Colorado, Boulder, CO (United States); Palo, Scott [Univ. of Colorado, Boulder, CO (United States); Argrow, Brian [Univ. of Colorado, Boulder, CO (United States); LoDolce, Gabriel [Univ. of Colorado, Boulder, CO (United States); Curry, Nathan [Univ. of Colorado, Boulder, CO (United States); Weibel, Douglas [Univ. of Colorado, Boulder, CO (United States); Finamore, William [Univ. of Colorado, Boulder, CO (United States); D' Amore, Phillip [Univ. of Colorado, Boulder, CO (United States); Borenstein, Steven [Univ. of Colorado, Boulder, CO (United States); Nichols, Tevis [Univ. of Colorado, Boulder, CO (United States); Elston, Jack [Blackswift Technologies, Boulder, CO (United States); Ivey, Mark [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bendure, Albert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schmid, Beat [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Long, Charles [Univ. of Colorado, Boulder, CO (United States); Telg, Hagen [Univ. of Colorado, Boulder, CO (United States); Gao, Ru-Shan [National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States); Hock, Terry [National Center for Atmospheric Research, Boulder, CO (United States); Bland, Geoff [NASA Ames Research Center (ARC), Moffett Field, Mountain View, CA (United States)

2017-03-29

This final technical report details activities undertaken as part of the referenced project. Included is information on the preparation of aircraft for deployment to Alaska, summaries of the three deployments covered under this project, and a brief description of the dataset and science directions pursued. Additionally, we provide information on lessons learned, publications, and presentations resulting from this work.

Proteomic approaches in research of cyanobacterial photosynthesis.

Science.gov (United States)

Battchikova, Natalia; Angeleri, Martina; Aro, Eva-Mari

2015-10-01

Oxygenic photosynthesis in cyanobacteria, algae, and plants is carried out by a fabulous pigment-protein machinery that is amazingly complicated in structure and function. Many different approaches have been undertaken to characterize the most important aspects of photosynthesis, and proteomics has become the essential component in this research. Here we describe various methods which have been used in proteomic research of cyanobacteria, and demonstrate how proteomics is implemented into on-going studies of photosynthesis in cyanobacterial cells.

Final Technical Report for contract number DE-FG02-05ER15670

Energy Technology Data Exchange (ETDEWEB)

Glazebrook, Jane [Univ. of Minnesota, Minneapolis, MN (United States)

2016-02-29

This is the final technical report for contract number DE-FG02-05ER15670. The project is now complete, and results of the project have been published. Two papers were published based on work done in the last three-year funding period. The DOIs of these papers are included below. The abstracts of the papers, providing summaries of the work, are included in the body of the report.

The Center for the Study of Early Events in Photosynthesis. Final report, September 1, 1988--August 31, 1994

Energy Technology Data Exchange (ETDEWEB)

Orr, L.A.

1994-12-31

The ASU Center for the Study of Early Events in Photosynthesis was established in 1988 with funding through a five-year grant from the USDA/DOE/NSF Plant Science Center program and a grant from the NSF Biological Facilities program. Its scientific objective is to elucidate the basic principles that govern photosynthetic energy collection and storage. Understanding these principles is vital to mankind, as photosynthesis provides most of our food, fiber and energy needs. The Center attempts to fulfill this objective through research of the highest standard, coupled inextricably with quality education at the undergraduate, graduate and postdoctoral levels. These goals are met via a network of collaborative, interdisciplinary research groups comprising 100 personnel within the Department of Chemistry and Biochemistry, the Department of Botany, and the Department of Physics and Astronomy. The work of these research groups is facilitated by the Center through a variety of important infrastructural functions.

INTERACTIVE ILUSTRATION FOR PHOTOSYNTHESIS TEACHING

Directory of Open Access Journals (Sweden)

M.R. Pereira

2004-05-01

Full Text Available Computational resources became the major tool in the challenge of making high education moreeasy and motivating. Complex Biochemical pathways can now be presented in interactive and three-dimensional animations. One of the most complex (detailed and interesting metabolic pathway thatstudents must understand in biochemical courses is photosynthesis. The light-dependent reactionsare of special interest since they involve many dierent kinds of mechanisms, as light absorptionby membrane complexes, proteins movement inside membranes, reactions of water hydrolysis, andelectrons ow; making it dicult to understand by static bi-dimensional representations.The resources of animation and ActionScript programming were used to make an interactive ani-mation of photosynthesis, which at some times even simulates three-dimensionality. The animationbegins with a leaf and progressively zooms in, until we have a scheme of a tylakoyd membrane, whereeach of the dierent steps of the pathway can be clicked to reveal a more detailed scheme of it. Whereappropriate, the energy graphs are shown side by side with the reactions. The electron is representedwith a face, so it can be shown to be stressing while going up in the energy graphs. Finally, there isa simplied version of the whole pathway, to illustrate how it all goes together.The objective is to help professors on teaching the subject in regular classes, since currently allthe explanations are omitted. In a future version, texts will be added to each step so it can beself-explicative to the students, helping them even on home or on-line learning.

Technical and logistic provisions for the delivery of radioactive wastes in the final repository Konrad

International Nuclear Information System (INIS)

Poeppinghaus, Jens

2013-01-01

The beginning of radioactive waste delivery to the final repository Konrad is planned for 2019. The main issue for the technical and logistic provisions is the development of a concept for the transport of the licensed radioactive waste containers to the site, including a turning concept for cylindrical waste forms and planning, construction and manufacture of transport equipment. Further issues include a logistic concept considering specific boundary conditions as administrative processes, priorities, special features of the delivering institutions and technical requirements of the repository.

Global Analysis of Photosynthesis Transcriptional Regulatory Networks

Science.gov (United States)

Imam, Saheed; Noguera, Daniel R.; Donohue, Timothy J.

2014-01-01

Photosynthesis is a crucial biological process that depends on the interplay of many components. This work analyzed the gene targets for 4 transcription factors: FnrL, PrrA, CrpK and MppG (RSP_2888), which are known or predicted to control photosynthesis in Rhodobacter sphaeroides. Chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) identified 52 operons under direct control of FnrL, illustrating its regulatory role in photosynthesis, iron homeostasis, nitrogen metabolism and regulation of sRNA synthesis. Using global gene expression analysis combined with ChIP-seq, we mapped the regulons of PrrA, CrpK and MppG. PrrA regulates ∼34 operons encoding mainly photosynthesis and electron transport functions, while CrpK, a previously uncharacterized Crp-family protein, regulates genes involved in photosynthesis and maintenance of iron homeostasis. Furthermore, CrpK and FnrL share similar DNA binding determinants, possibly explaining our observation of the ability of CrpK to partially compensate for the growth defects of a ΔFnrL mutant. We show that the Rrf2 family protein, MppG, plays an important role in photopigment biosynthesis, as part of an incoherent feed-forward loop with PrrA. Our results reveal a previously unrealized, high degree of combinatorial regulation of photosynthetic genes and significant cross-talk between their transcriptional regulators, while illustrating previously unidentified links between photosynthesis and the maintenance of iron homeostasis. PMID:25503406

Global analysis of photosynthesis transcriptional regulatory networks.

Directory of Open Access Journals (Sweden)

Saheed Imam

2014-12-01

Full Text Available Photosynthesis is a crucial biological process that depends on the interplay of many components. This work analyzed the gene targets for 4 transcription factors: FnrL, PrrA, CrpK and MppG (RSP_2888, which are known or predicted to control photosynthesis in Rhodobacter sphaeroides. Chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq identified 52 operons under direct control of FnrL, illustrating its regulatory role in photosynthesis, iron homeostasis, nitrogen metabolism and regulation of sRNA synthesis. Using global gene expression analysis combined with ChIP-seq, we mapped the regulons of PrrA, CrpK and MppG. PrrA regulates ∼34 operons encoding mainly photosynthesis and electron transport functions, while CrpK, a previously uncharacterized Crp-family protein, regulates genes involved in photosynthesis and maintenance of iron homeostasis. Furthermore, CrpK and FnrL share similar DNA binding determinants, possibly explaining our observation of the ability of CrpK to partially compensate for the growth defects of a ΔFnrL mutant. We show that the Rrf2 family protein, MppG, plays an important role in photopigment biosynthesis, as part of an incoherent feed-forward loop with PrrA. Our results reveal a previously unrealized, high degree of combinatorial regulation of photosynthetic genes and significant cross-talk between their transcriptional regulators, while illustrating previously unidentified links between photosynthesis and the maintenance of iron homeostasis.

Model systems in photosynthesis research

International Nuclear Information System (INIS)

Katz, J.J.; Hindman, J.C.

1981-01-01

After a general discussion of model studies in photosynthesis research, three recently developed model systems are described. The current status of covalently linked chlorophyll pairs as models for P700 and P865 is first briefly reviewed. Mg-tris(pyrochlorophyllide)1,1,1-tris(hydroxymethyl) ethane triester in its folded configuration is then discussed as a rudimentary antenna-photoreaction center model. Finally, self-assembled chlorophyll systems that contain a mixture of monomeric, oligomeric and special pair chlorophyll are shown to have fluorescence emission characteristics that resemble thoe of intact Tribonema aequale at room temperature in that both show fluorescence emission at 675 and 695 nm. In the self-assembled systems the wavelength of the emitted fluorescence depends on the wavelength of excitation, arguing that energy transfer between different chlorophyll species in these systems may be more complex than previously suspected

Reintroducing Photosynthesis

Science.gov (United States)

Vila, F.; Sanz, A.

2012-01-01

This article reports on conceptual difficulties related to photosynthesis and respiratory metabolism of a Plant Physiology course for undergraduate students that could hinder their better learning of metabolic processes. A survey of results obtained in this area during the last 10 academic years was performed, as well as a specific test, aimed to…

Correlated charge-changing uion-atom collisions. Final Technical Report

International Nuclear Information System (INIS)

John Tanis

2005-01-01

This document comprises the final technical report for atomic collisions research supported by DOE grant No. DE-FG02-87ER13778 from September 1, 2001 through August 31, 2004. The research involved the experimental investigation of excitation and charge-changing processes occurring in ion-atom and ion-molecule collisions. Major emphases of the study were: (1) interference effects resulting from coherent electron emission in H2, (2) production of doubly vacant K-shell (hollow ion) states due to electron correlation, and (3) formation of long-lived metastable states in electron transfer processes. During the period of the grant, this research resulted in 23 publications, 12 invited presentations, and 39 contributed presentations at national and international meetings and other institutions. Brief summaries of the completed research are presented below

FERMI(at)Elettra FEL Design Technical Optimization Final Report

International Nuclear Information System (INIS)

Fawley, William; Penn, Gregory; Allaria, Enrico; De Ninno, Giovanni; Graves, William

2006-01-01

This is the final report of the FEL Design Group for the Technical Optimization Study for the FERMI(at)ELETTRA project. The FERMI(at)ELETTRA project is based on the principle of harmonic upshifting of an initial ''seed'' signal in a single pass, FEL amplifier employing multiple undulators. There are a number of FEL physics principles which underlie this approach to obtaining short wavelength output: (1) the energy modulation of the electron beam via the resonant interaction with an external laser seed (2) the use of a chromatic dispersive section to then develop a strong density modulation with large harmonic overtones (3) the production of coherent radiation by the microbunched beam in a downstream radiator. Within the context of the FERMI project, we discuss each of these elements in turn

Toward a mechanistic modeling of nitrogen limitation for photosynthesis

Science.gov (United States)

Xu, C.; Fisher, R. A.; Travis, B. J.; Wilson, C. J.; McDowell, N. G.

2011-12-01

The nitrogen limitation is an important regulator for vegetation growth and global carbon cycle. Most current ecosystem process models simulate nitrogen effects on photosynthesis based on a prescribed relationship between leaf nitrogen and photosynthesis; however, there is a large amount of variability in this relationship with different light, temperature, nitrogen availability and CO2 conditions, which can affect the reliability of photosynthesis prediction under future climate conditions. To account for the variability in nitrogen-photosynthesis relationship under different environmental conditions, in this study, we developed a mechanistic model of nitrogen limitation for photosynthesis based on nitrogen trade-offs among light absorption, electron transport, carboxylization and carbon sink. Our model shows that strategies of nitrogen storage allocation as determined by tradeoff among growth and persistence is a key factor contributing to the variability in relationship between leaf nitrogen and photosynthesis. Nitrogen fertilization substantially increases the proportion of nitrogen in storage for coniferous trees but much less for deciduous trees, suggesting that coniferous trees allocate more nitrogen toward persistence compared to deciduous trees. The CO2 fertilization will cause lower nitrogen allocation for carboxylization but higher nitrogen allocation for storage, which leads to a weaker relationship between leaf nitrogen and maximum photosynthesis rate. Lower radiation will cause higher nitrogen allocation for light absorption and electron transport but less nitrogen allocation for carboxylyzation and storage, which also leads to weaker relationship between leaf nitrogen and maximum photosynthesis rate. At the same time, lower growing temperature will cause higher nitrogen allocation for carboxylyzation but lower allocation for light absorption, electron transport and storage, which leads to a stronger relationship between leaf nitrogen and maximum

The role of carbonic anhydrase in C₄ photosynthesis

Energy Technology Data Exchange (ETDEWEB)

Studer, Anthony [Life Sciences Research Foundation, Baltimore, MD (United States)

2015-10-01

Current pressures on the global food supply have accelerated the urgency for a second green revolution using novel and sustainable approaches to increase crop yield and efficiency. This proposal outlines experiments to address fundamental questions regarding the biology of C₄ photosynthesis, the method of carbon fixation utilized by the most productive food, feed and bioenergy crops. Carbonic anhydrase (CA) has been implicated in multiple cellular functions including nitrogen metabolism, water use efficiency, and photosynthesis. CA catalyzes the first dedicated step in C₄ photosynthesis, the hydration of CO₂ into bicarbonate, and is potentially rate limiting in C₄ grasses. Using insertional mutagenesis, we have generated CA mutants in maize, and propose the characterization of these mutants using phenotypic, physiological, and transcriptomic profiling to assay the plant’s response to altered CA activity. In addition, florescent protein tagging experiments will be employed to study the subcellular localization of CA paralogs, providing critical data for modeling carbon fixation in C₄ plants. Finally, I propose parallel experiments in Setaria viridis to explore its relevance as model C₄ grass. Using a multifaceted approach, this proposal addresses important questions in basic biology, as well as the need for translation research in response to looming global food challenges.

SIMS study on statistics and environmental factors in health. Final technical report to Department of Energy

International Nuclear Information System (INIS)

1982-07-01

This final technical report to DOE consists of five individual technical reports and one working paper by members of the SIMS Study at Stanford. Research topics include testing goodness-of-fit for the distribution of errors in regression models, mathematical models of cancer and their use in risk assessment, pollutant standards index (Psi), osteosarcomas among beagles exposed to 239 Plutonium, air pollution and respiratory disease, and models of human exposure to air pollution. Individual summaries of the six reports are indexed separately

Final Technical Report DOE/GO/13142-1

Energy Technology Data Exchange (ETDEWEB)

Patrick Mulvihill; Quang Nguyen

2010-09-15

This research adds to the understanding of the areas of residual starch and biomass conversion to alcohol, by providing data from pilot plant equipment of larger scale than the minimum required to give commercially scalable data. Instrumentation and control is in place to capture the information produced, for economic and technical evaluation. The impact of rheology, recycle streams, and residence time distributions on the technical and economic performance can be assessed. Various processes can be compared technically and economically because the pilot plants are readily modifiable. Several technologies for residual starch yield improvement have been identified, implemented, and patent applications filed. Various biomass-to-ethanol processes have been compared and one selected for technical optimization and commercialization. The technical and economic feasibility of the current simplified biomass conversion process is being confirmed by intensive pilot plant efforts as of this writing. Optimization of the feedstock handling and pretreatment is occurring to increase the alcohol yield above the minimum commercially viable level already demonstrated. Samples of biomass residue and reactor blowdown condensate are being collected to determine the technical and economic performance of the high-water-recycle waste treatment system being considered for the process. The project is of benefit to the public because it is advancing the efforts to achieve low-cost fermentable substrates for conversion to transportation fuels. This process combines the hydrolysis of agricultural residues with novel enzymes and organisms to convert the sugars released to transportation fuels. The process development is taking place at a scale allowing commercial development to proceed at a rapid pace.

Community photosynthesis of aquatic macrophytes

DEFF Research Database (Denmark)

Binzer, T.; Sand-Jensen, K.; Middelboe, A. L.

2006-01-01

We compared 190 photosynthesis-irradiance (P-E) experiments with single- and multispecies communities of macroalgae and vascular plants from freshwater and marine habitats. We found a typical hyperbolic P-E relation in all communities and no sign of photosaturation or photoinhibition of photosynt......We compared 190 photosynthesis-irradiance (P-E) experiments with single- and multispecies communities of macroalgae and vascular plants from freshwater and marine habitats. We found a typical hyperbolic P-E relation in all communities and no sign of photosaturation or photoinhibition...

Physiological basis of genetic variation in leaf photosynthesis among rice (Oryza sativa L.) introgression lines under drought and well-watered conditions

Science.gov (United States)

Yin, Xinyou

2012-01-01

To understand the physiological basis of genetic variation and resulting quantitative trait loci (QTLs) for photosynthesis in a rice (Oryza sativa L.) introgression line population, 13 lines were studied under drought and well-watered conditions, at flowering and grain filling. Simultaneous gas exchange and chlorophyll fluorescence measurements were conducted at various levels of incident irradiance and ambient CO2 to estimate parameters of a model that dissects photosynthesis into stomatal conductance (g s), mesophyll conductance (g m), electron transport capacity (J max), and Rubisco carboxylation capacity (V cmax). Significant genetic variation in these parameters was found, although drought and leaf age accounted for larger proportions of the total variation. Genetic variation in light-saturated photosynthesis and transpiration efficiency (TE) were mainly associated with variation in g s and g m. One previously mapped major QTL of photosynthesis was associated with variation in g s and g m, but also in J max and V cmax at flowering. Thus, g s and g m, which were demonstrated in the literature to be responsible for environmental variation in photosynthesis, were found also to be associated with genetic variation in photosynthesis. Furthermore, relationships between these parameters and leaf nitrogen or dry matter per unit area, which were previously found across environmental treatments, were shown to be valid for variation across genotypes. Finally, the extent to which photosynthesis rate and TE can be improved was evaluated. Virtual ideotypes were estimated to have 17.0% higher photosynthesis and 25.1% higher TE compared with the best genotype investigated. This analysis using introgression lines highlights possibilities of improving both photosynthesis and TE within the same genetic background. PMID:22888131

Enhancing (crop) plant photosynthesis by introducing novel genetic diversity.

Science.gov (United States)

Dann, Marcel; Leister, Dario

2017-09-26

Although some elements of the photosynthetic light reactions might appear to be ideal, the overall efficiency of light conversion to biomass has not been optimized during evolution. Because crop plants are depleted of genetic diversity for photosynthesis, efforts to enhance its efficiency with respect to light conversion to yield must generate new variation. In principle, three sources of natural variation are available: (i) rare diversity within extant higher plant species, (ii) photosynthetic variants from algae, and (iii) reconstruction of no longer extant types of plant photosynthesis. Here, we argue for a novel approach that outsources crop photosynthesis to a cyanobacterium that is amenable to adaptive evolution. This system offers numerous advantages, including a short generation time, virtually unlimited population sizes and high mutation rates, together with a versatile toolbox for genetic manipulation. On such a synthetic bacterial platform, 10 000 years of (crop) plant evolution can be recapitulated within weeks. Limitations of this system arise from its unicellular nature, which cannot reproduce all aspects of crop photosynthesis. But successful establishment of such a bacterial host for crop photosynthesis promises not only to enhance the performance of eukaryotic photosynthesis but will also reveal novel facets of the molecular basis of photosynthetic flexibility.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'. © 2017 The Author(s).

Hydrogen Production from Water by Photosynthesis System I for Use as Fuel in Energy Conversion Devices (a.k.a. Understanding Photosystem I as a Biomolecular Reactor for Energy Conversion)

Science.gov (United States)

2014-04-01

Hydrogen Production from Water by Photosynthesis System I for Use as Fuel in Energy Conversion Devices (a.k.a. Understanding Photosystem I as...Laboratory Adelphi, MD 20783-1197 ARL-TR-6904 April 2014 Hydrogen Production from Water by Photosynthesis System I for Use as Fuel in Energy...Final 3. DATES COVERED (From - To) 10/1/2010–10/1/2013 4. TITLE AND SUBTITLE Hydrogen Production from Water by Photosynthesis System I for Use as Fuel

CARBON DIOXIDE MITIGATION THROUGH CONTROLLED PHOTOSYNTHESIS; FINAL

International Nuclear Information System (INIS)

Unknown

2000-01-01

This research was undertaken to meet the need for a robust portfolio of carbon management options to ensure continued use of coal in electrical power generation. In response to this need, the Ohio Coal Research Center at Ohio University developed a novel technique to control the emissions of CO(sub 2) from fossil-fired power plants by growing organisms capable of converting CO(sub 2) to complex sugars through the process of photosynthesis. Once harvested, the organisms could be used in the production of fertilizer, as a biomass fuel, or fermented to produce alcohols. In this work, a mesophilic organism, Nostoc 86-3, was examined with respect to the use of thermophilic algae to recycle CO(sub 2) from scrubbed stack gases. The organisms were grown on stationary surfaces to facilitate algal stability and promote light distribution. The testing done throughout the year examined properties of CO(sub 2) concentration, temperature, light intensity, and light duration on process viability and the growth of the Nostoc. The results indicate that the Nostoc species is suitable only in a temperature range below 125 F, which may be practical given flue gas cooling. Further, results indicate that high lighting levels are not suitable for this organism, as bleaching occurs and growth rates are inhibited. Similarly, the organisms do not respond well to extended lighting durations, requiring a significant (greater than eight hour) dark cycle on a consistent basis. Other results indicate a relative insensitivity to CO(sub 2) levels between 7-12% and CO levels as high as 800 ppm. Other significant results alluded to previously, relate to the development of the overall process. Two processes developed during the year offer tremendous potential to enhance process viability. First, integration of solar collection and distribution technology from Oak Ridge laboratories could provide a significant space savings and enhanced use of solar energy. Second, the use of translating slug flow

Soil Temperature Triggers the Onset of Photosynthesis in Korean Pine

Science.gov (United States)

Wu, Jiabing; Guan, Dexin; Yuan, Fenhui; Wang, Anzhi; Jin, Changjie

2013-01-01

In forest ecosystems, the onset of spring photosynthesis may have an important influence on the annual carbon balance. However, triggers for the onset of photosynthesis have yet to be clearly identified, especially for temperate evergreen conifers. The effects of climatic factors on recovery of photosynthetic capacity in a Korean pine forest were investigated in the field. No photosynthesis was detectable when the soil temperature was below 0°C even if the air temperature was far beyond 15°C. The onset of photosynthesis and sap flow was coincident with the time of soil thawing. The rates of recovery of photosynthetic capacity highly fluctuated with air temperature after onset of photosynthesis, and intermittent frost events remarkably inhibited the photosynthetic capacity of the needles. The results suggest that earlier soil thawing is more important than air temperature increases in triggering the onset of photosynthesis in Korean pine in temperate zones under global warming scenarios. PMID:23755227

DOE FINAL TECHNICAL REPORT RP

Energy Technology Data Exchange (ETDEWEB)

RUSS PETERMAN

2012-01-01

The City of Georgetown Utility Systems (GUS) patnered with the private sector, the American Public Power Association (APPA) and Southwestern University to design, construct, test and monitor a solar co-generation system directly connected to the GUS electric distribution system. This report consists of the Primary Technical Report and 3 attachments.

Energy conversion in natural and artificial photosynthesis.

Science.gov (United States)

McConnell, Iain; Li, Gonghu; Brudvig, Gary W

2010-05-28

Modern civilization is dependent upon fossil fuels, a nonrenewable energy source originally provided by the storage of solar energy. Fossil-fuel dependence has severe consequences, including energy security issues and greenhouse gas emissions. The consequences of fossil-fuel dependence could be avoided by fuel-producing artificial systems that mimic natural photosynthesis, directly converting solar energy to fuel. This review describes the three key components of solar energy conversion in photosynthesis: light harvesting, charge separation, and catalysis. These processes are compared in natural and in artificial systems. Such a comparison can assist in understanding the general principles of photosynthesis and in developing working devices, including photoelectrochemical cells, for solar energy conversion. 2010 Elsevier Ltd. All rights reserved.

New Concept of Photosynthesis

Directory of Open Access Journals (Sweden)

Komissarov Gennadiy Germanovich

2014-12-01

Full Text Available The history of the formation of a new concept of photosynthesis proposed by the author is considered for the period since 1966 to 2013. Its essence consists in the following facts: the photosynthetic oxygen (hydrogen source is not water, but exo- and endogenous hydrogen peroxide; thermal energy is a necessary part of the photosynthetic process; along with the carbon dioxide the air (oxygen, inert gases is included in the photosynthetic equation. The mechanism of the photovoltaic (Becquerel effect in films of chlorophyll and its synthetic analogue - phthalocyanine are briefly touched upon in the article. The article presents the works on artificial photosynthesis performed in the laboratory of Photobionics of N.N. Semenov Institute of Chemical Physics, RAS.

Technical support document for the surface disposal of sewage sludge. Final report

International Nuclear Information System (INIS)

1992-11-01

The document provides the technical background and justification for the U.S. Environmental Protection Agency's (EPA) final regulation (40 CFR Part 503) covering the surface disposal of sewage sludge. The document summarizes current practices in land application and presents data supporting the risk assessment methodology used to derive human health and environmental risk-based limits for contaminants in sewage sludge placed on surface disposal sites. The management practices associated with surface disposal are outlined and the different pathways by which contaminants reach highly-exposed individuals (HEIs) through surface disposal are discussed

Technical support document for the surface disposal of sewage sludge. Final report

Energy Technology Data Exchange (ETDEWEB)

1992-11-01

The document provides the technical background and justification for the U.S. Environmental Protection Agency's (EPA) final regulation (40 CFR Part 503) covering the surface disposal of sewage sludge. The document summarizes current practices in land application and presents data supporting the risk assessment methodology used to derive human health and environmental risk-based limits for contaminants in sewage sludge placed on surface disposal sites. The management practices associated with surface disposal are outlined and the different pathways by which contaminants reach highly-exposed individuals (HEIs) through surface disposal are discussed.

Techniques in studies of photosynthesis

International Nuclear Information System (INIS)

Kumarasinghe, K.S.

1990-01-01

The use of both stable and radioactive isotopes has led to major advances in the understanding of the basic mechanisms of photosynthesis. An early use of isotopic material in photosynthetic investigations was the demonstration using 18 O, that O 2 evolved in photosynthesis was derived from water rather than from CO 2 . When the long-lived isotope of carbon, 14 C, became available in 1945, its use, coupled with two-dimensional chromatography developed a few years earlier, enabled Calvin and Benson (1948) to devise experiments to elucidate the pathway of photosynthetic 14 CO 2 fixation, 12 refs, 6 figs, 10 tabs

The paleobiological record of photosynthesis.

Science.gov (United States)

William Schopf, J

2011-01-01

Fossil evidence of photosynthesis, documented in Precambrian sediments by microbially laminated stromatolites, cyanobacterial microscopic fossils, and carbon isotopic data consistent with the presence of Rubisco-mediated CO2-fixation, extends from the present to ~3,500 million years ago. Such data, however, do not resolve time of origin of O2-producing photoautotrophy from its anoxygenic, bacterial, evolutionary precursor. Though it is well established that Earth's ecosystem has been based on autotrophy since its very early stages, the time of origin of oxygenic photosynthesis, more than 2,450 million years ago, has yet to be established.

Technical assistance contractor Management Plan. Final [report

Energy Technology Data Exchange (ETDEWEB)

1993-09-01

The Technical Assistance Contractor (TAC) for the Uranium Mill Tailings Remedial Action (UMTRA) Project comprises Jacobs Engineering Group Inc. (JEG) and its major teaming partners [Roy F. Weston, Inc. (RFW), Sergent, Hauskins & Beckwith Agra, Inc. (SHB Agra), and Geraghty & Miller, Inc. (G&M)]. The first three companies have worked together effectively on the UMTRA Project for more than 10 years. With the initiation of the UMTRA Groundwater Project in April 1991, a need arose to increase the TAC`s groundwater technical breadth and depth, so G&M was brought in to augment the team`s capabilities. The TAC contract`s scope is to provide technical, analytical, environmental, engineering, design, inspection, and management support services to the US Department of Energy (DOE) for both surface and groundwater projects. The TAC team continues to support the DOE in completing surface remedial actions and initiating groundwater remediation work for start-up, characterization, design, construction oversight, and remedial operations. A key feature of the TAC`s management approach is the extensive set of communication systems implemented for the UMTRA Project. These systems assist all functional disciplines in performing UMTRA Project tasks associated with management, technical support, administrative support, and financial/project controls.

Experimental Program Final Technical Progress Report: 15 February 2007 to 30 September 2012

Energy Technology Data Exchange (ETDEWEB)

Kinney, Edward R. [University of Colorado, Boulder, CO

2014-09-12

This is the final technical report of the grant DE-FG02-04ER41301 to the University of Colorado at Boulder entitled "Intermediate Energy Nuclear Physics" and describes the results of our funded activities during the period 15 February 2007 to 30 September 2012. These activities were primarily carried out at Fermilab, RHIC, and the German lab DESY. Significant advances in these experiments were carried out by members of the Colorado group and are described in detail.

Challenges in Understanding Photosynthesis in a University Introductory Biosciences Class

Science.gov (United States)

Södervik, Ilona; Virtanen, Viivi; Mikkilä-Erdmann, Mirjamaija

2015-01-01

University students' understanding of photosynthesis was examined in a large introductory biosciences class. The focus of this study was to first examine the conceptions of photosynthesis among students in class and then to investigate how a certain type of text could enhance students' understanding of photosynthesis. The study was based on pre-…

Identification and characterization of nuclear genes involved in photosynthesis in Populus

Science.gov (United States)

2014-01-01

Background The gap between the real and potential photosynthetic rate under field conditions suggests that photosynthesis could potentially be improved. Nuclear genes provide possible targets for improving photosynthetic efficiency. Hence, genome-wide identification and characterization of the nuclear genes affecting photosynthetic traits in woody plants would provide key insights on genetic regulation of photosynthesis and identify candidate processes for improvement of photosynthesis. Results Using microarray and bulked segregant analysis strategies, we identified differentially expressed nuclear genes for photosynthesis traits in a segregating population of poplar. We identified 515 differentially expressed genes in this population (FC ≥ 2 or FC ≤ 0.5, P photosynthesis by the nuclear genome mainly involves transport, metabolism and response to stimulus functions. Conclusions This study provides new genome-scale strategies for the discovery of potential candidate genes affecting photosynthesis in Populus, and for identification of the functions of genes involved in regulation of photosynthesis. This work also suggests that improving photosynthetic efficiency under field conditions will require the consideration of multiple factors, such as stress responses. PMID:24673936

[Experimental study on crop photosynthesis, transpiration and high efficient water use].

Science.gov (United States)

Wang, Huixiao; Liu, Changming

2003-10-01

It is well known that the development of water-saving agriculture is a strategic choice for getting rid of the crisis of water shortage. In this paper, the crop photosynthesis, transpiration, stomatic behavior, and their affecting factors were studied in view of increasing the crop water use efficiency. The experimental results showed that there was a parabola relationship between photosynthesis and transpiration. The transpiration at the maximum photosynthesis was a critical value, above which, transpiration was the luxurious part. The luxurious transpiration could be controlled without affecting photosynthetic production. It is possible that the measures for increasing stomatic resistance and preventing transpiration could save water, and improve photosynthesis and yield as well. The photosynthesis rate increased with photosynthetic active radiation, and the light saturation point for photosynthesis existed. The light saturation point of dry treatment was much lower than that of wet treatment, and the relationship between transpiration and radiation was linear. When the photosynthetic active radiation was bigger than 1,000 mumol.m-2.s-1, some treatments could be carried out for decreasing transpiration and improving photosynthesis.

Technical Report - FINAL

Energy Technology Data Exchange (ETDEWEB)

Barbara Luke, Director, UNLV Engineering Geophysics Laboratory

2007-04-25

Improve understanding of the earthquake hazard in the Las Vegas Valley and to assess the state of preparedness of the area's population and structures for the next big earthquake. 1. Enhance the seismic monitoring network in the Las Vegas Valley 2. Improve understanding of deep basin structure through active-source seismic refraction and reflection testing 3. Improve understanding of dynamic response of shallow sediments through seismic testing and correlations with lithology 4. Develop credible earthquake scenarios by laboratory and field studies, literature review and analyses 5. Refine ground motion expectations around the Las Vegas Valley through simulations 6. Assess current building standards in light of improved understanding of hazards 7. Perform risk assessment for structures and infrastructures, with emphasis on lifelines and critical structures 8. Encourage and facilitate broad and open technical interchange regarding earthquake safety in southern Nevada and efforts to inform citizens of earthquake hazards and mitigation opportunities

An Approach to Developing Independent Learning and Non-Technical Skills Amongst Final Year Mining Engineering Students

Science.gov (United States)

Knobbs, C. G.; Grayson, D. J.

2012-01-01

There is mounting evidence to show that engineers need more than technical skills to succeed in industry. This paper describes a curriculum innovation in which so-called "soft" skills, specifically inter-personal and intra-personal skills, were integrated into a final year mining engineering course. The instructional approach was…

Final Technical Report for SISGR: Ultrafast Molecular Scale Chemical Imaging

Energy Technology Data Exchange (ETDEWEB)

Hersam, Mark C. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Guest, Jeffrey R. [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Guisinger, Nathan P. [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Hla, Saw Wai [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Schatz, George C. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Seideman, Tamar [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Van Duyne, Richard P. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry

2017-04-10

The Northwestern-Argonne SISGR program utilized newly developed instrumentation and techniques including integrated ultra-high vacuum tip-enhanced Raman spectroscopy/scanning tunneling microscopy (UHV-TERS/STM) and surface-enhanced femtosecond stimulated Raman scattering (SE-FSRS) to advance the spatial and temporal resolution of chemical imaging for the study of photoinduced dynamics of molecules on plasmonically active surfaces. An accompanying theory program addressed modeling of charge transfer processes using constrained density functional theory (DFT) in addition to modeling of SE-FSRS, thereby providing a detailed description of the excited state dynamics. This interdisciplinary and highly collaborative research resulted in 62 publications with ~ 48% of them being co-authored by multiple SISGR team members. A summary of the scientific accomplishments from this SISGR program is provided in this final technical report.

Secondary Students' Interpretations of Photosynthesis and Plant Nutrition.

Science.gov (United States)

Ozay, Esra; Oztas, Haydar

2003-01-01

Studies misconceptions held by grade 9 students (14-15-years old) in Turkey about photosynthesis and plant nutrition. Uses a questionnaire to test students' conceptions and reports conflicting and often incorrect ideas about photosynthesis, respiration, and energy flow in plants. Suggests that there are difficulties in changing students' prior…

Aerosol-induced thermal effects increase modelled terrestrial photosynthesis and transpiration

International Nuclear Information System (INIS)

Steiner, Allison L.; Chameides, W.L.

2005-01-01

Previous studies suggest that the radiative effects of atmospheric aerosols (reducing total radiation while increasing the diffuse fraction) can enhance terrestrial productivity. Here, simulations using a regional climate/terrestrial biosphere model suggest that atmospheric aerosols could also enhance terrestrial photosynthesis and transpiration through an interaction between solar radiation, leaf temperature and stomatal conductance. During midday, clear-sky conditions, sunlit-leaf temperatures can exceed the optimum for photosynthesis, depressing both photosynthesis and transpiration. Aerosols decrease surface solar radiation, thereby reducing leaf temperatures and enhancing sunlit-leaf photosynthesis and transpiration. This modelling study finds that, under certain conditions, this thermal response of aerosols can have a greater impact on photosynthesis and transpiration than the radiative response. This implies that a full understanding of the impact of aerosols on climate and the global carbon cycle requires consideration of the biophysical responses of terrestrial vegetation as well as atmospheric radiative and thermodynamic effects

Elevated CO2 increases photosynthesis in fluctuating irradiance regardless of photosynthetic induction state

NARCIS (Netherlands)

Kaiser, Elias; Zhou, Dianfan; Heuvelink, Ep; Harbinson, Jeremy; Morales Sierra, A.; Marcelis, Leo F.M.

2017-01-01

Leaves are often exposed to fluctuating irradiance, which limits assimilation. Elevated CO2 enhances dynamic photosynthesis (i.e. photosynthesis in fluctuating irradiance) beyond its effects on steady-state photosynthesis rates. Studying the role of CO2 in dynamic photosynthesis is important for

Gaps in knowledge and data driving uncertainty in models of photosynthesis.

Science.gov (United States)

Dietze, Michael C

2014-02-01

Regional and global models of the terrestrial biosphere depend critically on models of photosynthesis when predicting impacts of global change. This paper focuses on identifying the primary data needs of these models, what scales drive uncertainty, and how to improve measurements. Overall, there is a need for an open, cross-discipline database on leaf-level photosynthesis in general, and response curves in particular. The parameters in photosynthetic models are not constant through time, space, or canopy position but there is a need for a better understanding of whether relationships with drivers, such as leaf nitrogen, are themselves scale dependent. Across time scales, as ecosystem models become more sophisticated in their representations of succession they needs to be able to approximate sunfleck responses to capture understory growth and survival. At both high and low latitudes, photosynthetic data are inadequate in general and there is a particular need to better understand thermal acclimation. Simple models of acclimation suggest that shifts in optimal temperature are important. However, there is little advantage to synoptic-scale responses and circadian rhythms may be more beneficial than acclimation over shorter timescales. At high latitudes, there is a need for a better understanding of low-temperature photosynthetic limits, while at low latitudes the need is for a better understanding of phosphorus limitations on photosynthesis. In terms of sampling, measuring multivariate photosynthetic response surfaces are potentially more efficient and more accurate than traditional univariate response curves. Finally, there is a need for greater community involvement in model validation and model-data synthesis.

Models for estimating photosynthesis parameters from in situ production profiles

Science.gov (United States)

Kovač, Žarko; Platt, Trevor; Sathyendranath, Shubha; Antunović, Suzana

2017-12-01

The rate of carbon assimilation in phytoplankton primary production models is mathematically prescribed with photosynthesis irradiance functions, which convert a light flux (energy) into a material flux (carbon). Information on this rate is contained in photosynthesis parameters: the initial slope and the assimilation number. The exactness of parameter values is crucial for precise calculation of primary production. Here we use a model of the daily production profile based on a suite of photosynthesis irradiance functions and extract photosynthesis parameters from in situ measured daily production profiles at the Hawaii Ocean Time-series station Aloha. For each function we recover parameter values, establish parameter distributions and quantify model skill. We observe that the choice of the photosynthesis irradiance function to estimate the photosynthesis parameters affects the magnitudes of parameter values as recovered from in situ profiles. We also tackle the problem of parameter exchange amongst the models and the effect it has on model performance. All models displayed little or no bias prior to parameter exchange, but significant bias following parameter exchange. The best model performance resulted from using optimal parameter values. Model formulation was extended further by accounting for spectral effects and deriving a spectral analytical solution for the daily production profile. The daily production profile was also formulated with time dependent growing biomass governed by a growth equation. The work on parameter recovery was further extended by exploring how to extract photosynthesis parameters from information on watercolumn production. It was demonstrated how to estimate parameter values based on a linearization of the full analytical solution for normalized watercolumn production and from the solution itself, without linearization. The paper complements previous works on photosynthesis irradiance models by analysing the skill and consistency of

DIMEC - Final Report

DEFF Research Database (Denmark)

Conrad, Finn

1997-01-01

Final report of the research project DIMEC - Danish InfoMechatronic Control supported by the Danish Technical Research Council, STVF.......Final report of the research project DIMEC - Danish InfoMechatronic Control supported by the Danish Technical Research Council, STVF....

Photosynthesis and the world food problem

Directory of Open Access Journals (Sweden)

Jerzy Poskuta

2014-01-01

Full Text Available Studies in the field of photosynthesis are particularly predisposed to play an important role in the solving of the main problem of today food for the world's growing population. The article presents data on the rate of population increase, the size of food production and yields of the most important crop plants. The relationship between the photosynthetic productivity of C3 and C4 plants and their yields is discussed. The problem of the rising atmospheric CO2 concentration and its influence on photosynthesis, photorespiration and accumulation of plant biomass is presented.

Final Technical Report: Hydrogen Codes and Standards Outreach

Energy Technology Data Exchange (ETDEWEB)

Hall, Karen I.

2007-05-12

This project contributed significantly to the development of new codes and standards, both domestically and internationally. The NHA collaborated with codes and standards development organizations to identify technical areas of expertise that would be required to produce the codes and standards that industry and DOE felt were required to facilitate commercialization of hydrogen and fuel cell technologies and infrastructure. NHA staff participated directly in technical committees and working groups where issues could be discussed with the appropriate industry groups. In other cases, the NHA recommended specific industry experts to serve on technical committees and working groups where the need for this specific industry expertise would be on-going, and where this approach was likely to contribute to timely completion of the effort. The project also facilitated dialog between codes and standards development organizations, hydrogen and fuel cell experts, the government and national labs, researchers, code officials, industry associations, as well as the public regarding the timeframes for needed codes and standards, industry consensus on technical issues, procedures for implementing changes, and general principles of hydrogen safety. The project facilitated hands-on learning, as participants in several NHA workshops and technical meetings were able to experience hydrogen vehicles, witness hydrogen refueling demonstrations, see metal hydride storage cartridges in operation, and view other hydrogen energy products.

Photosynthesis 2008 Gordon Research Conferences - June 22-27, 2008

Energy Technology Data Exchange (ETDEWEB)

Willem Vermaas

2009-08-28

Photosynthesis is the most prevalent, natural way to convert solar energy to chemical energy in living systems, and is a major mechanism to ameliorate rising CO2 levels in the atmosphere and to contribute to sustainable biofuels production. Photosynthesis is a particularly interdisciplinary field of research, with contributions from plant and microbial physiology, biochemistry, spectroscopy, etc. The Photosynthesis GRC is a venue by which scientists with expertise in complementary approaches such as solar energy conversion, molecular mechanisms of electron transfer, and 'systems biology' (molecular physiology) of photosynthetic organisms come together to exchange data and ideas and to forge new collaborations. The 2008 Photosynthesis GRC will focus on important new findings related to, for example: (1) function, structure, assembly, degradation, motility and regulation of photosynthetic complexes; (2) energy and electron transfer in photosynthetic systems; regulation and rate limitations; (3) synthesis, degradation and regulation of cofactors (pigments, etc.); (4) functional, structural and regulatory interactions between photosynthesis and the physiology of the organism; (5) organisms with unusual photosynthetic properties, and insights from metagenomics and evolution; and (6) bioenergy strategies involving solar energy conversion, and practical applications for photosynthetic organisms.

Scientific Conceptions of Photosynthesis among Primary School Pupils and Student Teachers of Biology

Directory of Open Access Journals (Sweden)

Darja Skribe Dimec

2017-03-01

Full Text Available Photosynthesis is the most important biochemical process on Earth. Most living beings depend on it directly or indirectly. Knowledge about photosynthesis enables us to understand how the world functions as an ecosystem and how photosynthesis acts as a bridge between the non-living and living worlds. It is, therefore, understandable that photosynthesis is included in national curricula around the world. The practice unfortunately shows that students at all school levels mostly learn about photosynthesis by rote. Consequently, they have difficulties understanding this vital process. Research also shows many misconceptions in relation to photosynthesis among students of different ages. Based on these, the main aim of our study was to explore the scientific conceptions about photosynthesis held by primary school pupils and student teachers of biology. Data were collected using a questionnaire containing seven biology content questions. The sample consisted of 634 participants, 427 primary school pupils (aged 11–14, and 207 student teachers of biology (aged 20–23. We found that the populations of primary school pupils and student teachers of biology differ greatly concerning scientific conceptions of photosynthesis. The student teachers showed good and complex understanding of photosynthesis, while pupils showed some misconceptions (location of chlorophyll and photosynthesis in a plant, transformation of energy in photosynthesis. Analysis of the development of scientific conceptions about photosynthesis with age showed that there is very little progress among primary school pupils and none among biology student teachers. More involvement of student teachers of biology in practical work at primary schools during their study was suggested to make student teachers aware of, and better understand pupils’ misconceptions.

General lighting requirements for photosynthesis

Energy Technology Data Exchange (ETDEWEB)

Geiger, D.R. [Univ. of Dayton, OH (United States)

1994-12-31

A review of the general lighting requirements for photosynthesis reveals that four aspects of light are important: irradiance, quality, timing and duration. These properties of light affect photosynthesis by providing the energy that drives carbon assimilation as well as by exerting control over physiology, structure and morphology of plants. Irradiance, expressed as energy flux, W m{sup -2}, or photon irradiance, {mu}mol m{sup -2} s{sup -1}, determines the rate at which energy is being delivered to the photosynthetic reaction centers. Spectral quality, the wavelength composition of light, is important because photons differ in their probability of being absorbed by the light harvesting complex and hence their ability to drive carbon assimilation. Also the various light receptors for light-mediated regulation of plant form and physiology have characteristic absorption spectra and hence photons differ in their effectiveness for eliciting responses. Duration is important because both carbon assimilation and regulation are affected by the total energy or integrated irradiance delivered during a given period. Many processes associated with photosynthesis are time-dependent, increasing or decreasing with duration. Timing is important because the effectiveness of light in the regulation of plant processes varies with the phase of the diumal cycle as determined by the plant`s time-measuring mechanisms.

Technical support document for land application of sewage sludge. Volume 1. Final report

International Nuclear Information System (INIS)

Jones, A.; Beyer, L.; Rookwood, M.; Pacenka, J.; Bergin, J.

1992-11-01

The document provides the technical background and justification for the U.S. Environmental Protection Agency's (EPA) final regulation (40 CFR Part 503) covering the land application of sewage sludge. The document summarizes current practices in land application and presents data supporting the risk assessment methodology used to derive human health and environmental risk-based limits for contaminants in land applied sewage sludge. The management practices associated with land application are outlined and the different pathways by which contaminants reach highly-exposed individuals (HEIs) through land application are discussed

Manganese and the Evolution of Photosynthesis

Science.gov (United States)

Fischer, Woodward W.; Hemp, James; Johnson, Jena E.

2015-09-01

Oxygenic photosynthesis is the most important bioenergetic event in the history of our planet—it evolved once within the Cyanobacteria, and remained largely unchanged as it was transferred to algae and plants via endosymbiosis. Manganese plays a fundamental role in this history because it lends the critical redox behavior of the water-oxidizing complex of photosystem II. Constraints from the photoassembly of the Mn-bearing water-oxidizing complex fuel the hypothesis that Mn(II) once played a key role as an electron donor for anoxygenic photosynthesis prior to the evolution of oxygenic photosynthesis. Here we review the growing body of geological and geochemical evidence from the Archean and Paleoproterozoic sedimentary records that supports this idea and demonstrates that the oxidative branch of the Mn cycle switched on prior to the rise of oxygen. This Mn-oxidizing phototrophy hypothesis also receives support from the biological record of extant phototrophs, and can be made more explicit by leveraging constraints from structural biology and biochemistry of photosystem II in Cyanobacteria. These observations highlight that water-splitting in photosystem II evolved independently from a homodimeric ancestral type II reaction center capable of high potential photosynthesis and Mn(II) oxidation, which is required by the presence of homologous redox-active tyrosines in the modern heterodimer. The ancestral homodimer reaction center also evolved a C-terminal extension that sterically precluded standard phototrophic electron donors like cytochrome c, cupredoxins, or high-potential iron-sulfur proteins, and could only complete direct oxidation of small molecules like Mn2+, and ultimately water.

Photosynthesis down-regulation precedes carbohydrate accumulation under sink limitation in Citrus.

Science.gov (United States)

Nebauer, Sergio G; Renau-Morata, Begoña; Guardiola, José Luis; Molina, Rosa-Victoria

2011-02-01

Photosynthesis down-regulation due to an imbalance between sources and sinks in Citrus leaves could be mediated by excessive accumulation of carbohydrates. However, there is limited understanding of the physiological role of soluble and insoluble carbohydrates in photosynthesis regulation and the elements triggering the down-regulation process. In this work, the role of non-structural carbohydrates in the regulation of photosynthesis under a broad spectrum of source-sink relationships has been investigated in the Salustiana sweet orange. Soluble sugar and starch accumulation in leaves, induced by girdling experiments, did not induce down-regulation of the photosynthetic rate in the presence of sinks (fruits). The leaf-to-fruit ratio did not modulate photosynthesis but allocation of photoassimilates to the fruits. The lack of strong sink activity led to a decrease in the photosynthetic rate and starch accumulation in leaves. However, photosynthesis down-regulation due to an excess of total soluble sugars or starch was discarded because photosynthesis and stomatal conductance reduction occurred prior to any significant accumulation of these carbohydrates. Gas exchange and fluorescence parameters suggested biochemical limitations to photosynthesis. In addition, the expression of carbon metabolism-related genes was altered within 24 h when strong sinks were removed. Sucrose synthesis and export genes were inhibited, whereas the expression of ADP-glucose pyrophosphorylase was increased to cope with the excess of assimilates. In conclusion, changes in starch and soluble sugar turnover, but not sugar content per se, could provide the signal for photosynthesis regulation. In these conditions, non-stomatal limitations strongly inhibited the photosynthetic rate prior to any significant increase in carbohydrate levels.

Artificial photosynthesis combines biology with technology for sustainable energy transformation

Science.gov (United States)

Moore, Thomas A.; Moore, Ana L.; Gust, Devens

2013-03-01

Photosynthesis supports the biosphere. Currently, human activity appropriates about one fourth of terrestrial photosynthetic net primary production (NPP) to support our GDP and nutrition. The cost to Earth systems of "our cut" of NPP is thought to be rapidly driving several Earth systems outside of bounds that were established on the geological time scale. Even with a fundamental realignment of human priorities, changing the unsustainable trajectory of the anthropocene will require reengineering photosynthesis to more efficiently meet human needs. Artificial photosynthetic systems are envisioned that can both supply renewable fuels and serve as platforms for exploring redesign strategies for photosynthesis. These strategies can be used in the nascent field of synthetic biology to make vast, much needed improvements in the biomass production efficiency of photosynthesis.

Photosynthesis: The Path of Carbon in Photosynthesis and the Primary Quantum Conversion Act of Photosynthesis

Science.gov (United States)

Calvin, Melvin

1952-11-22

This constitutes a review of the path of carbon in photosynthesis as it has been elaborated through the summer of 1952, with particular attention focused on those aspects of carbon metabolism and its variation which have led to some direct information regarding the primary quantum conversion act. An introduction to the arguments which have been adduced in support of the idea that chlorophyll is a physical sensitizer handing its excitation on to thioctic acid, a compound containing a strained 1, 2 -dithiolcyclopentane ring, is given.

Underwater Photosynthesis of Submerged Plants – Recent Advances and Methods

Science.gov (United States)

Pedersen, Ole; Colmer, Timothy D.; Sand-Jensen, Kaj

2013-01-01

We describe the general background and the recent advances in research on underwater photosynthesis of leaf segments, whole communities, and plant dominated aquatic ecosystems and present contemporary methods tailor made to quantify photosynthesis and carbon fixation under water. The majority of studies of aquatic photosynthesis have been carried out with detached leaves or thalli and this selectiveness influences the perception of the regulation of aquatic photosynthesis. We thus recommend assessing the influence of inorganic carbon and temperature on natural aquatic communities of variable density in addition to studying detached leaves in the scenarios of rising CO2 and temperature. Moreover, a growing number of researchers are interested in tolerance of terrestrial plants during flooding as torrential rains sometimes result in overland floods that inundate terrestrial plants. We propose to undertake studies to elucidate the importance of leaf acclimation of terrestrial plants to facilitate gas exchange and light utilization under water as these acclimations influence underwater photosynthesis as well as internal aeration of plant tissues during submergence. PMID:23734154

Increased sink strength offsets the inhibitory effect of sucrose on sugarcane photosynthesis.

Science.gov (United States)

Ribeiro, Rafael V; Machado, Eduardo C; Magalhães Filho, José R; Lobo, Ana Karla M; Martins, Márcio O; Silveira, Joaquim A G; Yin, Xinyou; Struik, Paul C

2017-01-01

Spraying sucrose inhibits photosynthesis by impairing Rubisco activity and stomatal conductance (g s ), whereas increasing sink demand by partially darkening the plant stimulates sugarcane photosynthesis. We hypothesized that the stimulatory effect of darkness can offset the inhibitory effect of exogenous sucrose on photosynthesis. Source-sink relationship was perturbed in two sugarcane cultivars by imposing partial darkness, spraying a sucrose solution (50mM) and their combination. Five days after the onset of the treatments, the maximum Rubisco carboxylation rate (V cmax ) and the initial slope of A-C i curve (k) were estimated by measuring leaf gas exchange and chlorophyll fluorescence. Photosynthesis was inhibited by sucrose spraying in both genotypes, through decreases in V cmax , k, g s and ATP production driven by electron transport (J atp ). Photosynthesis of plants subjected to the combination of partial darkness and sucrose spraying was similar to photosynthesis of reference plants for both genotypes. Significant increases in V cmax , g s and J atp and marginal increases in k were noticed when combining partial darkness and sucrose spraying compared with sucrose spraying alone. Our data also revealed that increases in sink strength due to partial darkness offset the inhibition of sugarcane photosynthesis caused by sucrose spraying, enhancing the knowledge on endogenous regulation of sugarcane photosynthesis through the source-sink relationship. Copyright © 2016 Elsevier GmbH. All rights reserved.

Microbial photosynthesis in the harnessing of solar energy

Energy Technology Data Exchange (ETDEWEB)

Pirt, S J

1982-01-01

The shortage of fossil fuels restricts the world supply of reduced carbon compounds and energy sources. Biotechnology offers the most feasible route to renewing the supplies of reduced carbon compounds. This involves recycling of CO/sub 2/ through photosynthesis. Conventional agriculture has little or no potential for supplying biomass and its derivatives on sufficient scale to offer an alternative to the fossil fuels. The agricultural wastes, on the whole, are intractable to conversion into useful carbon and energy sources and in any case are not available in amounts to provide a significant alternative to the fossil fuels. In contrast, microbial photosynthesis, optimised in photobioreactors, has vast potential to provide organic matter on a scale to match the consumption of fossil fuels. The quantative study of microbial photosynthesis as a biotechnological route to biomass has been neglected. As a result there is a chaos of conflicting data on fundamental parameters, for example, the photosynthetic efficiency of biomass production. New photosynthetic biotechnology with fully controlled continuous-culture systems is providing unequivocal values for the parameters. For the scale-up of microbial photosynthesis a tubular-loop reactor is proposed. (Refs. 14).

Observed and predicted measurements of photosynthesis in a phytoplankton culture exposed to natural irradiance

International Nuclear Information System (INIS)

Marra, J.; Heinemann, K.; Landriau, G. Jr.

1985-01-01

Photosynthesis-irradiance (P-I) curves were produced (using artificial illumination) from samples taken at one or more times per day from a continuous culture illuminated with sunlight. The continuous culture housed an oxygen electrode used to measure photosynthesis semi-continuously. Rates of photosynthesis predicted from P-I curves agreed with photosynthesis observed in the culture only for days of low irradiance. For sunny days or for days of variable irradiance, P-I curves predicted neither the morning photosynthesis maximum nor the afternoon depression. Daily integrals of predicted and observed photosynthesis, however, were probably within the possible errors of measurement. (orig.)

Auxin transport in leafy pea stem cuttings is partially driven by photosynthesis

International Nuclear Information System (INIS)

Kumpula, C.L.; Potter, J.R.

1987-01-01

When 14 C-IAA was applied to the apex of disbudded leafy pea stem cuttings (15 cm long), the movement of 14 C-IAA to the base of the cuttings after 24 h was influenced by the photosynthetic rate. In the absence of photosynthesis, light did not influence 14 C-IAA movement. Photosynthesis was altered by varying light, CO 2 concentration, or stomatal aperature (blocked with an antitranspirant). Radioactivity (identified by co-chromatography) was 25, 60, and 5% IAA, IAA-aspartate, and indolealdehyde respectively regardless of treatment. Adventitious root formation was reduced 50 to 95% and movement of IAA was inhibited 50 to 70% by decreasing gross photosynthesis 90 to 100%. Apparently, photosynthesis partially drives the movement of IAA from the apex to the base where roots arise. This gives a probably role of photosynthesis in rooting, because in this system virtually no rooting will take place without exogenous auxin and at least a low level of gross photosynthesis

Photosynthesis efficiency for different wavelengths; Fotosynthese-efficiency bij verschillende golflengten

Energy Technology Data Exchange (ETDEWEB)

Snel, J.F.H.; Meinen, E.; Bruins, M.A.; Van Ieperen, W.; Hogewoning, S.W.; Marcelis, L.F.M. [Wageningen UR Glastuinbouw, Wageningen (Netherlands)

2012-04-15

LED lighting has recently been introduced into Dutch horticulture. LED development so far indicates that in the near future LED's will be more energy efficient than high pressure sodium lamps. Crop light interception and photosynthesis efficiency are wavelength dependent. Therefore, LED colours for maximum crop photosynthesis, growth and development should be identified. Wageningen UR has investigated light interception and photosynthesis at different wavelengths for tomato, cucumber and rose. Measuring protocols and equipment were developed for leaf photosynthesis measurements in the laboratory and in greenhouses. A crop simulation model was used for up-scaling the leaf level results to crop level photosynthesis. For the vegetable crops the photosynthesis spectra are very similar to the generalised photosynthesis spectrum. Red light is most efficient for leaf photosynthesis. Light from red (ca. 645nm) LED's was maximally 13% more efficient than High Pressure Sodium light. For reddish leaves of the rose cultivar Prestige, red LED light was up to 35% more efficient. These figures apply to the momentary efficiency of leaf photosynthesis at 100 {mu}mol.m{sup -2}.s{sup -1} (PAR) and suggest that use of red light can lead to higher photosynthesis, especially for certain rose cultivars [Dutch] LED verlichting heeft zijn intrede gedaan in de Nederlandse glastuinbouw. De LED ontwikkeling laat zien dat in de nabije toekomst LED's efficiënter zijn dan SON-T verlichting. Lichtonderschepping en fotosynthese efficiëntie zijn afhankelijk van de kleur van het licht. Voor optimale fotosynthese, groei en ontwikkeling zouden de beste LED kleuren uitgezocht moeten worden. Wageningen UR heeft lichtonderschepping en fotosynthese bij verschillende lichtkleuren onderzocht bij tomaat, komkommer en roos. Protocollen en apparatuur werden ontwikkeld voor meting van bladfotosynthese en lichtonderschepping in het laboratorium en in de kas. Met een gewassimulatiemodel werd de

Exploring Undergraduates' Understanding of Photosynthesis Using Diagnostic Question Clusters

Science.gov (United States)

Parker, Joyce M.; Anderson, Charles W.; Heidemann, Merle; Merrill, John; Merritt, Brett; Richmond, Gail; Urban-Lurain, Mark

2012-01-01

We present a diagnostic question cluster (DQC) that assesses undergraduates' thinking about photosynthesis. This assessment tool is not designed to identify individual misconceptions. Rather, it is focused on students' abilities to apply basic concepts about photosynthesis by reasoning with a coordinated set of practices based on a few scientific…

Final Technical Progress Report: Development of Low-Cost Suspension Heliostat; December 7, 2011 - December 6, 2012

Energy Technology Data Exchange (ETDEWEB)

Bender, W.

2013-01-01

Final technical progress report of SunShot Incubator Solaflect Energy. The project succeeded in demonstrating that the Solaflect Suspension Heliostat design is viable for large-scale CSP installations. Canting accuracy is acceptable and is continually improving as Solaflect improves its understanding of this design. Cost reduction initiatives were successful, and there are still many opportunities for further development and further cost reduction.

Effects of fungicides on endophytic fungi and photosynthesis in seedlings of a tropical tree, guarea guidonia (meliaceae)

International Nuclear Information System (INIS)

Gamboa Gaitan, Miguel A; Wen, Shiyun; Fetcher, Ned; Bayman, Paul

2005-01-01

Endophytes are microorganisms that live within healthy plant tissues, and include fungi and bacteria. They can be mutualists, comensals or even latent pathogens. Presence of these endosymbionts may affect host physiology, for example by consuming products of photosynthesis (endophytes are heterotrophs) or producing toxic metabolites. In this work two fungicides were used to eliminate fungal endophytes from seedlings of guarea guidonia. light saturated photosynthesis (Amax) was measured in endophytefree plants and compared with control plants. Each fungicide killed different fungal endosymbionts. phomopsis was more susceptible to benomyl while colletotrichum was more susceptible to propiconazole. Although suggestive, values of Amax were not significantly different for each treatment compared with control plants. No prediction can be made at this point about the final outcome of a given plantendophytic fungi interaction

Powered by light: Phototrophy and photosynthesis in prokaryotes and its evolution.

Science.gov (United States)

Nowicka, Beatrycze; Kruk, Jerzy

2016-01-01

Photosynthesis is a complex metabolic process enabling photosynthetic organisms to use solar energy for the reduction of carbon dioxide into biomass. This ancient pathway has revolutionized life on Earth. The most important event was the development of oxygenic photosynthesis. It had a tremendous impact on the Earth's geochemistry and the evolution of living beings, as the rise of atmospheric molecular oxygen enabled the development of a highly efficient aerobic metabolism, which later led to the evolution of complex multicellular organisms. The mechanism of photosynthesis has been the subject of intensive research and a great body of data has been accumulated. However, the evolution of this process is not fully understood, and the development of photosynthesis in prokaryota in particular remains an unresolved question. This review is devoted to the occurrence and main features of phototrophy and photosynthesis in prokaryotes. Hypotheses concerning the origin and spread of photosynthetic traits in bacteria are also discussed. Copyright © 2016 Elsevier GmbH. All rights reserved.

The Path of Carbon in Photosynthesis VIII. The Role of Malic Acid

Science.gov (United States)

Bassham, James A.; Benson, Andrew A.; Calvin, Melvin

1950-01-25

Malonate has been found to inhibit the formation of malic acid during short periods of photosynthesis with radioactive carbon dioxide. This result, together with studies which show the photosynthetic cycle to be operating normally at the same time, indicates that malic acid is not an intermediate in photosynthesis but is probably closely related to some intermediate of the cycle. Absence of labeled succinic and fumaric acids in these experiments, in addition to the failure of malonate to inhibit photosynthesis, precludes the participation of these acids as intermediates in photosynthesis.

Exploring Photosynthesis and Plant Stress Using Inexpensive Chlorophyll Fluorometers

Science.gov (United States)

Cessna, Stephen; Demmig-Adams, Barbara; Adams, William W., III

2010-01-01

Mastering the concept of photosynthesis is of critical importance to learning plant physiology and its applications, but seems to be one of the more challenging concepts in biology. This teaching challenge is no doubt compounded by the complexity by which plants alter photosynthesis in different environments. Here we suggest the use of chlorophyll…

NEET-AMM Final Technical Report on Laser Direct Manufacturing (LDM) for Nuclear Power Components

International Nuclear Information System (INIS)

Anderson, Scott; Baca, Georgina; O'Connor, Michael

2015-01-01

Final technical report summarizes the program progress and technical accomplishments of the Laser Direct Manufacturing (LDM) for Nuclear Power Components project. A series of experiments varying build process parameters (scan speed and laser power) were conducted at the outset to establish the optimal build conditions for each of the alloys. Fabrication was completed in collaboration with Quad City Manufacturing Laboratory (QCML). The density of all sample specimens was measured and compared to literature values. Optimal build process conditions giving fabricated part densities close to literature values were chosen for making mechanical test coupons. Test coupons whose principal axis is on the x-y plane (perpendicular to build direction) and on the z plane (parallel to build direction) were built and tested as part of the experimental build matrix to understand the impact of the anisotropic nature of the process.. Investigations are described 316L SS, Inconel 600, 718 and 800 and oxide dispersion strengthed 316L SS (Yttria) alloys.

NEET-AMM Final Technical Report on Laser Direct Manufacturing (LDM) for Nuclear Power Components

Energy Technology Data Exchange (ETDEWEB)

Anderson, Scott [Lockheed Martin Corporation, Denver, CO (United States). Space Systems Company; Baca, Georgina [Lockheed Martin Corporation, Denver, CO (United States). Space Systems Company; O' Connor, Michael [Lockheed Martin Corporation, Denver, CO (United States). Space Systems Company

2015-12-31

Final technical report summarizes the program progress and technical accomplishments of the Laser Direct Manufacturing (LDM) for Nuclear Power Components project. A series of experiments varying build process parameters (scan speed and laser power) were conducted at the outset to establish the optimal build conditions for each of the alloys. Fabrication was completed in collaboration with Quad City Manufacturing Laboratory (QCML). The density of all sample specimens was measured and compared to literature values. Optimal build process conditions giving fabricated part densities close to literature values were chosen for making mechanical test coupons. Test coupons whose principal axis is on the x-y plane (perpendicular to build direction) and on the z plane (parallel to build direction) were built and tested as part of the experimental build matrix to understand the impact of the anisotropic nature of the process.. Investigations are described 316L SS, Inconel 600, 718 and 800 and oxide dispersion strengthed 316L SS (Yttria) alloys.

On the relation between phototaxis and photosynthesis in Rhodospirillum Rubrum

NARCIS (Netherlands)

Thomas, J.B.; Nijenhuis, L.E.

1950-01-01

The relation between phototaxis and photosynthesis in Rhodospirillum rubrum has been studied. The light intensity at which saturation is reached in photosynthesis proved to coincide with that at which the contrast sensitivity starts to decrease. Potassium cyanide, which preferably inhibits the

The primary steps of photosynthesis

International Nuclear Information System (INIS)

Fleming, G.R.; Van Grondelle, R.

1996-01-01

The two important initial steps of photosynthesis-electron transfer and energy transfer occur with great speed and efficiency. New techniques in laser optics and genetic engineering age helping us to understand why. (author). 24 refs. 8 figs

Manganese-based Materials Inspired by Photosynthesis for Water-Splitting

Directory of Open Access Journals (Sweden)

Harvey J.M. Hou

2011-09-01

Full Text Available In nature, the water-splitting reaction via photosynthesis driven by sunlight in plants, algae, and cyanobacteria stores the vast solar energy and provides vital oxygen to life on earth. The recent advances in elucidating the structures and functions of natural photosynthesis has provided firm framework and solid foundation in applying the knowledge to transform the carbon-based energy to renewable solar energy into our energy systems. In this review, inspired by photosynthesis robust photo water-splitting systems using manganese-containing materials including Mn-terpy dimer/titanium oxide, Mn-oxo tetramer/Nafion, and Mn-terpy oligomer/tungsten oxide, in solar fuel production are summarized and evaluated. Potential problems and future endeavors are also discussed.

Quantum design of photosynthesis for bio-inspired solar-energy conversion

NARCIS (Netherlands)

Romero, Elisabet; Novoderezhkin, Vladimir I.; van Grondelle, Rienk

2017-01-01

Photosynthesis is the natural process that converts solar photons into energy-rich products that are needed to drive the biochemistry of life. Two ultrafast processes form the basis of photosynthesis: excitation energy transfer and charge separation. Under optimal conditions, every photon that is

Technical basis for the ITER final design report, cost review and safety analysis (FDR)

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-12-01

The ITER final design report, cost review and safety analysis (FDR) is the 4th major milestone, representing the progress made in the ITER Engineering Design Activities. With the approval of the Detailed Design Report (DDR), the design work was concentrated on the requirements of operation, with only relatively minor changes to design concepts of major components. The FDR is the culmination of almost 6 years collaborative design and supporting technical work by the ITER Joint Central Team and Home Teams under the terms of the ITER EDA Agreement. Refs, figs, tabs

Technical basis for the ITER final design report, cost review and safety analysis (FDR)

International Nuclear Information System (INIS)

1998-01-01

The ITER final design report, cost review and safety analysis (FDR) is the 4th major milestone, representing the progress made in the ITER Engineering Design Activities. With the approval of the Detailed Design Report (DDR), the design work was concentrated on the requirements of operation, with only relatively minor changes to design concepts of major components. The FDR is the culmination of almost 6 years collaborative design and supporting technical work by the ITER Joint Central Team and Home Teams under the terms of the ITER EDA Agreement

Technical review of externalities issues. Final report

International Nuclear Information System (INIS)

Niemeyer, V.

1994-12-01

Externalities has become the catchword for a major experiment in electric utility regulation. Together with increased competition as a means for economic regulation, this experiment represents a potential revolution in how electric utilities are regulated. It is very important for utilities and policy makers to understand the technical issues and arguments driving the externality experiment. This Technical Review presents four papers covering topics in economics that may play important roles in this revolution. The four papers are: Economic Issues in the Application of Externalities to Electricity Resource Selection; Climate Change, the Marginal Cost of Carbon Dioxide Emissions and the Implications for Carbon Dioxide Emissions Adders; Positive Externalities and Benefits from Electricity; and Socioeconomic Effects of Externality Adders for Electric Utility Emissions

[Photosynthesis and transpiration characteristics of female and male Trichosanthes kirilowii Maxim individuals].

Science.gov (United States)

Liu, Yun; Zhong, Zhang-cheng; Wang, Xiao-xue; Xie, Jun; Yang, Wen-ying

2011-03-01

A field research was conducted on the photosynthesis and transpiration characteristics of dioecious Trichosanthes kirilowii individuals at four key development stages. At vegetative growth stage, the photosynthesis rate, transpiration rate, stomatal conductance, and water use efficiency of male individuals were higher than those of female individuals, and hence, male individuals entered into reproductive growth stage 22 days earlier than female individuals. After entering into reproductive growth stage, male individuals had higher photosynthesis rate, transpiration rate, and stomatal conductance, but slightly lower water use efficiency than female individuals. As the female individuals started to reproductive growth, their photosynthesis rate and water use efficiency were significantly lower, while the transpiration rate and stomatal conductance were higher than those of the male individuals. The effects of climate factors on the growth and development of T. kirilowii mainly occurred at its vegetative growth and early reproductive growth stages, and weakened at later reproductive growth stages. Higher temperature and lower relative humidity benefited the growth and development of T. kirilowii, and illumination could enhance the photosynthesis rate of T. kirilowii, especially its male individuals. After entering into reproductive growth stage, the photosynthesis rate of male individuals increased significantly with increasing illumination, but that of female individuals only had a slight increase, and the transpiration rate of male individuals as well as the photosynthesis rate of female individuals all increased significantly with increasing temperature.

Cyanobacterial photosynthesis under sulfidic conditions: insights from the isolate Leptolyngbya sp. strain hensonii

Science.gov (United States)

Hamilton, Trinity L; Klatt, Judith M; de Beer, Dirk; Macalady, Jennifer L

2018-01-01

We report the isolation of a pinnacle-forming cyanobacterium isolated from a microbial mat covering the sediment surface at Little Salt Spring—a flooded sinkhole in Florida with a perennially microoxic and sulfidic water column. The draft genome of the isolate encodes all of the enzymatic machinery necessary for both oxygenic and anoxygenic photosynthesis, as well as genes for methylating hopanoids at the C-2 position. The physiological response of the isolate to H2S is complex: (i) no induction time is necessary for anoxygenic photosynthesis; (ii) rates of anoxygenic photosynthesis are regulated by both H2S and irradiance; (iii) O2 production is inhibited by H2S concentrations as low as 1 μM and the recovery rate of oxygenic photosynthesis is dependent on irradiance; (iv) under the optimal light conditions for oxygenic photosynthesis, rates of anoxygenic photosynthesis are nearly double those of oxygenic photosynthesis. We hypothesize that the specific adaptation mechanisms of the isolate to H2S emerged from a close spatial interaction with sulfate-reducing bacteria. The new isolate, Leptolyngbya sp. strain hensonii, is not closely related to other well-characterized Cyanobacteria that can perform anoxygenic photosynthesis, which further highlights the need to characterize the diversity and biogeography of metabolically versatile Cyanobacteria. The isolate will be an ideal model organism for exploring the adaptation of Cyanobacteria to sulfidic conditions. PMID:29328062

Cyanobacterial photosynthesis under sulfidic conditions: insights from the isolate Leptolyngbya sp. strain hensonii.

Science.gov (United States)

Hamilton, Trinity L; Klatt, Judith M; de Beer, Dirk; Macalady, Jennifer L

2018-02-01

We report the isolation of a pinnacle-forming cyanobacterium isolated from a microbial mat covering the sediment surface at Little Salt Spring-a flooded sinkhole in Florida with a perennially microoxic and sulfidic water column. The draft genome of the isolate encodes all of the enzymatic machinery necessary for both oxygenic and anoxygenic photosynthesis, as well as genes for methylating hopanoids at the C-2 position. The physiological response of the isolate to H 2 S is complex: (i) no induction time is necessary for anoxygenic photosynthesis; (ii) rates of anoxygenic photosynthesis are regulated by both H 2 S and irradiance; (iii) O 2 production is inhibited by H 2 S concentrations as low as 1 μM and the recovery rate of oxygenic photosynthesis is dependent on irradiance; (iv) under the optimal light conditions for oxygenic photosynthesis, rates of anoxygenic photosynthesis are nearly double those of oxygenic photosynthesis. We hypothesize that the specific adaptation mechanisms of the isolate to H 2 S emerged from a close spatial interaction with sulfate-reducing bacteria. The new isolate, Leptolyngbya sp. strain hensonii, is not closely related to other well-characterized Cyanobacteria that can perform anoxygenic photosynthesis, which further highlights the need to characterize the diversity and biogeography of metabolically versatile Cyanobacteria. The isolate will be an ideal model organism for exploring the adaptation of Cyanobacteria to sulfidic conditions.

A model for chlorophyll fluorescence and photosynthesis at leaf scale

NARCIS (Netherlands)

Tol, van der C.; Verhoef, W.; Rosema, A.

2009-01-01

This paper presents a leaf biochemical model for steady-state chlorophyll fluorescence and photosynthesis of C3 and C4 vegetation. The model is a tool to study the relationship between passively measured steady-state chlorophyll fluorescence and actual photosynthesis, and its evolution during the

From molecules to materials pathways to artificial photosynthesis

CERN Document Server

Rozhkova, Elena A

2015-01-01

This interdisciplinary book focuses on the various aspects transformation of the energy from sunlight into the chemical bonds of a fuel, known as the artificial photosynthesis, and addresses the emergent challenges connected with growing societal demands for clean and sustainable energy technologies. The editors assemble the research of world-recognized experts in the field of both molecular and materials artificial systems for energy production. Contributors cover the full scope of research on photosynthesis and related energy processes.

Technical study gas storage. Final report

International Nuclear Information System (INIS)

Borowka, J.; Moeller, A.; Zander, W.; Koischwitz, M.A.

2001-01-01

This study will answer the following questions: (a) For what uses was the storage facility designed and for what use is it currently applied? Provide an overview of the technical data per gas storage facility: for instance, what is its capacity, volume, start-up time, etc.; (b) How often has this facility been used during the past 10 years? With what purpose was the facility brought into operation at the time? How much gas was supplied at the time from the storage facility?; (c) Given the characteristics and the use of the storage facility during the past 10 years and projected gas consumption in the future, how will the storage facility be used in the future?; (d) Are there other uses for which the gas storage facility can be deployed, or can a single facility be deployed for numerous uses? What are the technical possibilities in such cases? Questions (a) and (b) are answered separately for every storage facility. Questions (c) and (d) in a single chapter each (Chapter 2 and 3). An overview of the relevant storage data relating to current use, use in the last 10 years and use in future is given in the Annex

Novel Genetic Tools to Accelerate Our Understanding of Photosynthesis and Lipid Accumulation

Science.gov (United States)

2014-08-20

understanding of photosynthesis and lipid accumulation Martin C. Jonikas, Ph.D. Carnegie Institution for Science, Department of Plant Biology 260...knowledge of algal lipid metabolism and photosynthesis . Advances in our basic understanding of these processes will facilitate genetic engineering of...algae to improve lipid yields. Currently, one of the greatest roadblocks in the study of algal photosynthesis and lipid metabolism is the slow pace of

Global artificial photosynthesis project: a scientific and legal introduction.

Science.gov (United States)

Faunce, Thomas

2011-12-01

With the global human population set to exceed 10 billion by 2050, its collective energy consumption to rise from 400 to over 500 EJ/yr and with the natural environment under increasing pressure from these sources as well as from anthropogenic climate change, political solutions such as the creation of an efficient carbon price and trading scheme may arrive too late. In this context, the scientific community is exploring technological remedies. Central to these options is artificial photosynthesis--the creation, particularly through nanotechnology, of devices capable to doing what plants have done for millions of years - transforming sunlight, water and carbon dioxide into food and fuel. This article argues that a Global Artificial Photosynthesis (GAP) project can raise the public profile and encourage the pace, complexity and funding of scientific collaborations in artificial photosynthesis research. The legal structure of a GAP project will be critical to prevent issues such as state sovereignty over energy and food resources and corporate intellectual monopoly privileges unduly inhibiting the important contribution of artificial photosynthesis to global public health and environmental sustainability. The article presents an introduction to the scientific and legal concepts behind a GAP project.

Photosynthesis Activates Plasma Membrane H+-ATPase via Sugar Accumulation.

Science.gov (United States)

Okumura, Masaki; Inoue, Shin-Ichiro; Kuwata, Keiko; Kinoshita, Toshinori

2016-05-01

Plant plasma membrane H(+)-ATPase acts as a primary transporter via proton pumping and regulates diverse physiological responses by controlling secondary solute transport, pH homeostasis, and membrane potential. Phosphorylation of the penultimate threonine and the subsequent binding of 14-3-3 proteins in the carboxyl terminus of the enzyme are required for H(+)-ATPase activation. We showed previously that photosynthesis induces phosphorylation of the penultimate threonine in the nonvascular bryophyte Marchantia polymorpha However, (1) whether this response is conserved in vascular plants and (2) the process by which photosynthesis regulates H(+)-ATPase phosphorylation at the plasma membrane remain unresolved issues. Here, we report that photosynthesis induced the phosphorylation and activation of H(+)-ATPase in Arabidopsis (Arabidopsis thaliana) leaves via sugar accumulation. Light reversibly phosphorylated leaf H(+)-ATPase, and this process was inhibited by pharmacological and genetic suppression of photosynthesis. Immunohistochemical and biochemical analyses indicated that light-induced phosphorylation of H(+)-ATPase occurred autonomously in mesophyll cells. We also show that the phosphorylation status of H(+)-ATPase and photosynthetic sugar accumulation in leaves were positively correlated and that sugar treatment promoted phosphorylation. Furthermore, light-induced phosphorylation of H(+)-ATPase was strongly suppressed in a double mutant defective in ADP-glucose pyrophosphorylase and triose phosphate/phosphate translocator (adg1-1 tpt-2); these mutations strongly inhibited endogenous sugar accumulation. Overall, we show that photosynthesis activated H(+)-ATPase via sugar production in the mesophyll cells of vascular plants. Our work provides new insight into signaling from chloroplasts to the plasma membrane ion transport mechanism. © 2016 American Society of Plant Biologists. All Rights Reserved.

78 FR 29239 - Final Priority; Technical Assistance To Improve State Data Capacity-National Technical Assistance...

Science.gov (United States)

2013-05-20

... Assistance To Improve State Data Capacity--National Technical Assistance Center To Improve State Capacity To... Education and Rehabilitative Services announces a priority under the Technical Assistance to Improve State... (FY) 2013 and later years. We take this action to focus attention on an identified national need to...

Application of microbial photosynthesis to energy production and CO2 fixation

International Nuclear Information System (INIS)

Asada, Y.; Miyake, J.

1994-01-01

This paper presents different applications of microbial photosynthesis for energy production and carbon dioxide fixation. The authors discuss about energetic aspects of photosynthesis and features of biological way for solar energy conversion. (TEC). 4 figs., 12 refs

Photosynthesis

DEFF Research Database (Denmark)

Pribil, Mathias; Leister, Dario Michael

2017-01-01

on the genetic engineering of developmental or bioenergetic processes, such as photosynthesis. These approaches offer the prospect of a renewal of the Green Revolution, which is urgently required tomeet the continuously increasing demand for superior high-yield crop varieties for human sustenance and industrial...... by exponential population growth and increased demand for crop plants as sources of renewable energy or high-value products. The foreseeable intensification of competition between agronomical and industrial use makes it imperative that the available supply of cropland be used more efficiently. During the Green...... Revolution that began in the 1960s, significant increases in yield could be achieved by more effective farming strategies, innovations in fertilization, and the introduction of dwarfing genes into important crop species like rice (Oryza sativa) and wheat (Triticum aestivum). The last resulted in a shift...

Phytotoxicity of chiral herbicide bromacil: Enantioselectivity of photosynthesis in Arabidopsis thaliana

Energy Technology Data Exchange (ETDEWEB)

Chen, Zunwei; Zou, Yuqin; Wang, Jia [MOE Key Laboratory of Environmental Remediation & Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Li, Meichao [Research Center of Analysis and Measurement, Zhejiang University of Technology, Hangzhou 310032 (China); Wen, Yuezhong, E-mail: wenyuezhong@zju.edu.cn [MOE Key Laboratory of Environmental Remediation & Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China)

2016-04-01

With the wide application of chiral herbicides and the frequent detection of photosystem II (PSII) herbicides, it is of great importance to assess the direct effects of PSII herbicides on photosynthesis in an enantiomeric level. In the present study, the enantioselective phytotoxicity of bromacil (BRO), typical photosynthesis inhibition herbicide, on Arabidopsis thaliana was investigated. The results showed that S-BRO exhibited a greater inhibition of electron transmission in photosystem I (PSI) of A. thaliana than R-BRO by inhibiting the transcription of fnr 1. S-BRO also changed the chlorophyll fluorescence parameters Y (II), Y (NO), and Y (NPQ) to a greater extent than R-Bro. Transcription of genes psbO2, Lhcb3 and Lhcb6 was down-regulated in an enantioselective rhythm and S-BRO caused more serious influence, indicating that S-BRO did worse damage to the photosystem II (PSII) of A. thaliana than R-BRO. This study suggested that S-BRO disturbed the photosynthesis of plants to a larger extent than R-BRO and provided a new sight to evaluate the phytotoxicity of chiral herbicides. - Highlights: • It is necessary to assess the direct effects of PSII herbicides on photosynthesis. • Phytotoxicity of bromacil is investigated in an enantiomeric level. • Bromacil disturbed enantioselectively the photosystem II of Arabidopsis thaliana. • S-bromacil caused severer damage to photosynthesis of Arabidopsis than R-bromacil. • Photosynthesis should be considered for phytotoxicity assessment of herbicides.

Phytotoxicity of chiral herbicide bromacil: Enantioselectivity of photosynthesis in Arabidopsis thaliana

International Nuclear Information System (INIS)

Chen, Zunwei; Zou, Yuqin; Wang, Jia; Li, Meichao; Wen, Yuezhong

2016-01-01

With the wide application of chiral herbicides and the frequent detection of photosystem II (PSII) herbicides, it is of great importance to assess the direct effects of PSII herbicides on photosynthesis in an enantiomeric level. In the present study, the enantioselective phytotoxicity of bromacil (BRO), typical photosynthesis inhibition herbicide, on Arabidopsis thaliana was investigated. The results showed that S-BRO exhibited a greater inhibition of electron transmission in photosystem I (PSI) of A. thaliana than R-BRO by inhibiting the transcription of fnr 1. S-BRO also changed the chlorophyll fluorescence parameters Y (II), Y (NO), and Y (NPQ) to a greater extent than R-Bro. Transcription of genes psbO2, Lhcb3 and Lhcb6 was down-regulated in an enantioselective rhythm and S-BRO caused more serious influence, indicating that S-BRO did worse damage to the photosystem II (PSII) of A. thaliana than R-BRO. This study suggested that S-BRO disturbed the photosynthesis of plants to a larger extent than R-BRO and provided a new sight to evaluate the phytotoxicity of chiral herbicides. - Highlights: • It is necessary to assess the direct effects of PSII herbicides on photosynthesis. • Phytotoxicity of bromacil is investigated in an enantiomeric level. • Bromacil disturbed enantioselectively the photosystem II of Arabidopsis thaliana. • S-bromacil caused severer damage to photosynthesis of Arabidopsis than R-bromacil. • Photosynthesis should be considered for phytotoxicity assessment of herbicides.

Daily xanthophyll cycle photoprotection in developing leaves prior to photosynthesis

Science.gov (United States)

M.N. Angelov; Shi-Jean S. Sung; C.C. Black

1995-01-01

There is widespread agreement that the xanthophyll cycle provides a major photoprotection system for photosynthesis in green leaves.Indeed this type of photoprotection seem to be ubiquitous for photosynthetic organisms. Photoprotection is provided via a rapid, near 10-13 sec, ability of zeaxanthin (Z) to dissipate excess light energy from photosynthesis because the...

Final waste classification and waste form technical position papers

International Nuclear Information System (INIS)

1983-05-01

The waste classification technical position paper describes overall procedures acceptable to NRC staff which may be used by licensees to determine the presence and concentrations of the radionuclides listed in section 61.55, and thereby classifying waste for near-surface disposal. This technical position paper also provides guidance on the types of information which should be included in shipment manifests accompanying waste shipments to near-surface disposal facilities. The technical position paper on waste form provides guidance to waste generators on test methods and results acceptable to NRC staff for implementing the 10 CFR Part 61 waste form requirements. It can be used as an acceptable approach for demonstrating compliance with the 10 CFR Part 61 waste structural stability criteria. This technical position paper includes guidance on processing waste into an acceptable stable form, designing acceptable high-integrity containers, packaging cartridge filters, and minimizing radiation effects on organic ion-exchange resins. The guidance in the waste form technical position paper may be used by licensees as the basis for qualifying process control programs to meet the waste form stability requirements, including tests which can be used to demonstrate resistance to degradation arising from the effects of compression, moisture, microbial activity, radiation, and chemical changes. Generic test data (e.g., topical reports prepared by vendors who market solidification technology) may be used for process control program qualification where such generic data is applicable to the particular types of waste generated by a licensee

NDH-Mediated Cyclic Electron Flow Around Photosystem I is Crucial for C4 Photosynthesis.

Science.gov (United States)

Ishikawa, Noriko; Takabayashi, Atsushi; Noguchi, Ko; Tazoe, Youshi; Yamamoto, Hiroshi; von Caemmerer, Susanne; Sato, Fumihiko; Endo, Tsuyoshi

2016-10-01

C 4 photosynthesis exhibits efficient CO 2 assimilation in ambient air by concentrating CO 2 around ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) through a metabolic pathway called the C 4 cycle. It has been suggested that cyclic electron flow (CEF) around PSI mediated by chloroplast NADH dehydrogenase-like complex (NDH), an alternative pathway of photosynthetic electron transport (PET), plays a crucial role in C 4 photosynthesis, although the contribution of NDH-mediated CEF is small in C 3 photosynthesis. Here, we generated NDH-suppressed transformants of a C 4 plant, Flaveria bidentis, and showed that the NDH-suppressed plants grow poorly, especially under low-light conditions. CO 2 assimilation rates were consistently decreased in the NDH-suppressed plants under low and medium light intensities. Measurements of non-photochemical quenching (NPQ) of Chl fluorescence, the oxidation state of the reaction center of PSI (P700) and the electrochromic shift (ECS) of pigment absorbance indicated that proton translocation across the thylakoid membrane is impaired in the NDH-suppressed plants. Since proton translocation across the thylakoid membrane induces ATP production, these results suggest that NDH-mediated CEF plays a role in the supply of ATP which is required for C 4 photosynthesis. Such a role is more crucial when the light that is available for photosynthesis is limited and the energy production by PET becomes rate-determining for C 4 photosynthesis. Our results demonstrate that the physiological contribution of NDH-mediated CEF is greater in C 4 photosynthesis than in C 3 photosynthesis, suggesting that the mechanism of PET in C 4 photosynthesis has changed from that in C 3 photosynthesis accompanying the changes in the mechanism of CO 2 assimilation. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Regulation of bacterial photosynthesis genes by the small noncoding RNA PcrZ.

Science.gov (United States)

Mank, Nils N; Berghoff, Bork A; Hermanns, Yannick N; Klug, Gabriele

2012-10-02

The small RNA PcrZ (photosynthesis control RNA Z) of the facultative phototrophic bacterium Rhodobacter sphaeroides is induced upon a drop of oxygen tension with similar kinetics to those of genes for components of photosynthetic complexes. High expression of PcrZ depends on PrrA, the response regulator of the PrrB/PrrA two-component system with a central role in redox regulation in R. sphaeroides. In addition the FnrL protein, an activator of some photosynthesis genes at low oxygen tension, is involved in redox-dependent expression of this small (s)RNA. Overexpression of full-length PcrZ in R. sphaeroides affects expression of a small subset of genes, most of them with a function in photosynthesis. Some mRNAs from the photosynthetic gene cluster were predicted to be putative PcrZ targets and results from an in vivo reporter system support these predictions. Our data reveal a negative effect of PcrZ on expression of its target mRNAs. Thus, PcrZ counteracts the redox-dependent induction of photosynthesis genes, which is mediated by protein regulators. Because PrrA directly activates photosynthesis genes and at the same time PcrZ, which negatively affects photosynthesis gene expression, this is one of the rare cases of an incoherent feed-forward loop including an sRNA. Our data identified PcrZ as a trans acting sRNA with a direct regulatory function in formation of photosynthetic complexes and provide a model for the control of photosynthesis gene expression by a regulatory network consisting of proteins and a small noncoding RNA.

Growth and photosynthesis of lettuce

NARCIS (Netherlands)

Holsteijn, van H.M.C.

1981-01-01

Butterhead lettuce is an important glass-house crop in the poor light period in The Netherlands. Fundamental data about the influence of temperature, light and CO ₂ on growth and photosynthesis are important e.g. to facilitate selection criteria for new cultivars. In

Assessing Photosynthesis by Fluorescence Imaging

Science.gov (United States)

Saura, Pedro; Quiles, Maria Jose

2011-01-01

This practical paper describes a novel fluorescence imaging experiment to study the three processes of photochemistry, fluorescence and thermal energy dissipation, which compete during the dissipation of excitation energy in photosynthesis. The technique represents a non-invasive tool for revealing and understanding the spatial heterogeneity in…

Inhibition of apparent photosynthesis by nitrogen oxides

Energy Technology Data Exchange (ETDEWEB)

Hill, A C; Bennett, J H

1970-01-01

The nitrogen oxides (NO/sub 2/ and NO) inhibited apparent photosynthesis of oats and alfalfa at concentrations below those required to cause visible injury. There appeared to be a threshold concentration of about 0.6 ppm for each pollutant. An additive effect in depressing apparent photosynthesis occurred when the plants were exposed to a mixture of NO and NO/sub 2/. Although NO produced a more rapid effect on the plants, lower concentrations of NO/sub 2/ were required to cause a given inhibition after 2 hour of exposure. Inhibition by nitric oxide was more closely related to its partial pressure than was inhibition by NO/sub 2/.

Photosynthesis: From De Saussure To Liebig.

Science.gov (United States)

Pennazio, Sergio

2017-01-01

The dawn of photosynthesis, characterized by the research of Priestley, Ingen- Housz and Senebier, culminated in 1804 with a historical essay of Théodore De Saussure. According to the historians, during the first half of the nineteenth century in which the genesis of the cell theory started off, the research on photosynthesis met a phase of stagnation. Indeed, the literature review of the period does not report particular innovation; however, several scientists (botanists, physiologists, and chemists) supported the thesis of De Saussure with a series of analyses that, in our opinion, deserve to be known. Mirbel, De Candolle, Raspail, Berzelius, Payen, Dutrochet, von Mohl, and other scholars attempted to expand knowledge on photosynthesis but were not able to arrive at a theory that was consistent with a functional mechanism, nor with a suitable chemical model to explain the transformation of the water and carbon dioxide into sugars. A classic case of such inadequacy concerns the discovery of chlorophyll. This compound, isolated in 1818 by Pelletier and Caventou, remained an enigma for many years and was never put in relation with the synthesis of starch. The accurate research of von Mohl led this scientist to believe that the granules of chlorophyll were entirely independent of starch granules, although in many cases these latter were observable inside the granules of chlorophyll. Only in the early forties, Justus von Liebig realized that the assimilation of carbon and hydrogen required a series of chemical reactions that, starting from some organic acids, ended in the formation of sugar. In conclusion, our analysis does not lead to define this period as stagnation but rather as transition, in which the concept of photosynthesis was clear, even though difficult to treat under physiological and chemical views. From the sixties, the researches of Julius von Sachs will open a new road, thanks also to the research carried out in the transition period. Copyright: �

Advantages and disadvantages on photosynthesis measurement ...

African Journals Online (AJOL)

PROMOTING ACCESS TO AFRICAN RESEARCH ... Through photosynthesis, green plants and cyanobacteria are able to transfer sunlight energy to ... Measurements of this process are useful in order to understand how it might be controlled ...

Enhancement of crop photosynthesis by diffuse light: quantifying the contributing factors.

Science.gov (United States)

Li, T; Heuvelink, E; Dueck, T A; Janse, J; Gort, G; Marcelis, L F M

2014-07-01

Plants use diffuse light more efficiently than direct light. However, experimental comparisons between diffuse and direct light have been obscured by co-occurring differences in environmental conditions (e.g. light intensity). This study aims to analyse the factors that contribute to an increase in crop photosynthesis in diffuse light and to quantify their relative contribution under different levels of diffuseness at similar light intensities. The hypothesis is that the enhancement of crop photosynthesis in diffuse light results not only from the direct effects of more uniform vertical and horizontal light distribution in the crop canopy, but also from crop physiological and morphological acclimation. Tomato (Solanum lycopersicum) crops were grown in three greenhouse compartments that were covered by glass with different degrees of light diffuseness (0, 45 and 71 % of the direct light being converted into diffuse light) while maintaining similar light transmission. Measurements of horizontal and vertical photosynthetic photon flux density (PPFD) distribution in the crop, leaf photosynthesis light response curves and leaf area index (LAI) were used to quantify each factor's contribution to an increase in crop photosynthesis in diffuse light. In addition, leaf temperature, photoinhibition, and leaf biochemical and anatomical properties were studied. The highest degree of light diffuseness (71 %) increased the calculated crop photosynthesis by 7·2 %. This effect was mainly attributed to a more uniform horizontal (33 % of the total effect) and vertical PPFD distribution (21 %) in the crop. In addition, plants acclimated to the high level of diffuseness by gaining a higher photosynthetic capacity of leaves in the middle of the crop and a higher LAI, which contributed 23 and 13 %, respectively, to the total increase in crop photosynthesis in diffuse light. Moreover, diffuse light resulted in lower leaf temperatures and less photoinhibition at the top of the canopy when

Water relations, thallus structure and photosynthesis in Negev Desert lichens

Science.gov (United States)

Palmer, R. J. Jr; Friedmann, E. I.

1990-01-01

The role of lichen thallus structure in water relations and photosynthesis was studied in Ramalina maciformis (Del.) Bory and Teloschistes lacunosus (Rupr.) Sav. Water-vapour adsorption and photosynthesis are dependent upon thallus integrity and are significantly lower in crushed thalli. Cultured phycobiont (Trebouxia sp.) cells are capable of photosynthesis over the same relative humidity range (> 80% RH) as are intact lichens. Thus, water-vapour adsorption by the thallus and physiological adaptation of the phycobiont contribute to the ability of these lichens to photosynthesize in an arid environment. Despite differences in their anatomical structure and water-uptake characteristics, their CO2 incorporation is similar. The two lichens use liquid water differently and they occupy different niches.

Pattern of photosynthesis in saline indica var. of rice Kala Rata

International Nuclear Information System (INIS)

Hegde, B.A.; Joshi, G.V.

1975-01-01

The present investigation on Kala Rata deals with the pattern of photosynthesis and the salt stress effect on the photosynthetic efficiency in rice. It is evident from the investigation that chlorophyll synthesis is enhanced with the increasing concentration of NaCl in the bathing medium. However, the efficiency of photosynthesis does not increase with increased chlorophyll production. All ions in leaves can stimulate CO 2 incorporation but inhibit at higher concentration. Analysis of short term products of photosynthesis revealed that aspartate is the major product to be heavily labelled which is evident from autoradiogram. PGA has also appreciable label, where as, malate has the least. It appears therefore, that in rice, both, Calvin as well as C 4 type of pathways are operating. 'Aspartate former' type of rice does not seem to be efficient in photosynthesis as it has C 3 pathway also in operation. (author)

Glucose Synthesis in a Protein-Based Artificial Photosynthesis System.

Science.gov (United States)

Lu, Hao; Yuan, Wenqiao; Zhou, Jack; Chong, Parkson Lee-Gau

2015-09-01

The objective of this study was to understand glucose synthesis of a protein-based artificial photosynthesis system affected by operating conditions, including the concentrations of reactants, reaction temperature, and illumination. Results from non-vesicle-based glyceraldehyde-3-phosphate (GAP) and glucose synthesis showed that the initial concentrations of ribulose-1,5-bisphosphate (RuBP) and adenosine triphosphate (ATP), lighting source, and temperature significantly affected glucose synthesis. Higher initial concentrations of RuBP and ATP significantly enhanced GAP synthesis, which was linearly correlated to glucose synthesis, confirming the proper functions of all catalyzing enzymes in the system. White fluorescent light inhibited artificial photosynthesis and reduced glucose synthesis by 79.2 % compared to in the dark. The reaction temperature of 40 °C was optimum, whereas lower or higher temperature reduced glucose synthesis. Glucose synthesis in the vesicle-based artificial photosynthesis system reconstituted with bacteriorhodopsin, F 0 F 1 ATP synthase, and polydimethylsiloxane-methyloxazoline-polydimethylsiloxane triblock copolymer was successfully demonstrated. This system efficiently utilized light-induced ATP to drive glucose synthesis, and 5.2 μg ml(-1) glucose was synthesized in 0.78-ml reaction buffer in 7 h. Light-dependent reactions were found to be the bottleneck of the studied artificial photosynthesis system.

The influence of temperature on photosynthesis of different tomato genotypes

NARCIS (Netherlands)

Gosiewski, W.; Nilwik, H.J.M.; Bierhuizen, J.F.

1982-01-01

Net photosynthesis and dark respiration from whole plants of various tomato genotypes were measured in a closed system. At low irradiance (27 W m−2) and low external CO2 concentration (550 mg m−3), net photosynthesis of 10 genotypes was found to vary between 0.122 and 0.209 mg CO2 m−2 s−1.

2009 Photosynthesis to be held June 28 - July 3, 2009

Energy Technology Data Exchange (ETDEWEB)

Doug Bruce

2009-07-06

The capture of solar energy by photosynthesis has had a most profound influence on the development and sustenance of life on earth. It is the engine that has driven the proliferation of life and, as the source of both energy and oxygen, has had a major hand in shaping the forms that life has taken. Both ancient and present day photosynthetic carbon fixation is intimately tied to issues of immediate human concern, global energy and global warming. Decreasing our reliance on fossil fuels by tapping photosynthesis in a more direct way is an attractive goal for sustainable energy. Meeting this challenge means understanding photosynthetic energy conversion at a molecular level, a task requiring perspectives ranging through all disciplines of science. Researchers in photosynthesis have a strong history of working across conventional boundaries and engaging in multidisciplinary collaborations. The Gordon conference in photosynthesis has been a key focal point for the dissemination of new results and the establishment of powerful research collaborations. In this spirit the 2009 Gordon conference on biophysical aspects of photosynthesis will bring together top international researchers from diverse and complementary disciplines, all working towards understanding how photosynthesis converts light into the stable chemical energy that powers so much of our world. Focal points for talks and discussions will include: (1) Watersplitting, structure and function of the oxygen evolving complex; (2) Antenna, the diversity, optimization and regulation of energy capture and transfer; (3) Reaction center structure and function, including functional roles for the protein; (4) Electron transport, proton transport and energy coupling; (5) Photoprotection mechanisms, including secondary electron transport pathways; (6) Biofuels, hydrogen production; and (7) Artificial photosynthesis and solar energy conversion strategies. The 2009 conference will have a close eye on practical applications

Increased SBPase activity improves photosynthesis and grain yield in wheat grown in greenhouse conditions.

Science.gov (United States)

Driever, Steven M; Simkin, Andrew J; Alotaibi, Saqer; Fisk, Stuart J; Madgwick, Pippa J; Sparks, Caroline A; Jones, Huw D; Lawson, Tracy; Parry, Martin A J; Raines, Christine A

2017-09-26

To meet the growing demand for food, substantial improvements in yields are needed. This is particularly the case for wheat, where global yield has stagnated in recent years. Increasing photosynthesis has been identified as a primary target to achieve yield improvements. To increase leaf photosynthesis in wheat, the level of the Calvin-Benson cycle enzyme sedoheptulose-1,7-biphosphatase (SBPase) has been increased through transformation and expression of a Brachypodium distachyon SBPase gene construct. Transgenic lines with increased SBPase protein levels and activity were grown under greenhouse conditions and showed enhanced leaf photosynthesis and increased total biomass and dry seed yield. This showed the potential of improving yield potential by increasing leaf photosynthesis in a crop species such as wheat. The results are discussed with regard to future strategies for further improvement of photosynthesis in wheat.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'. © 2017 The Authors.

Alumina reinforced tetragonal zirconia (TZP) composites. Final technical report, July 1, 1993--December 31, 1996

International Nuclear Information System (INIS)

Shetty, D.K.

1997-01-01

This final technical report summarizes the significant research results obtained during the period July 1, 1993 through December 31, 1996 in the DOE-supported research project entitled, open-quotes Alumina Reinforced Tetragonal Zirconia (TZP) Compositesclose quotes. The objective of the research was to develop high-strength and high-toughness ceramic composites by combining mechanisms of platelet, whisker or fiber reinforcement with transformation toughening. The approach used included reinforcement of Celia- or yttria-partially-stabilized zirconia (Ce-TZP or Y-TZP) with particulates, platelets, or continuous filaments of alumina

Final Scientific/Technical Report

Energy Technology Data Exchange (ETDEWEB)

Pakrasi, Himadri B. [Washington Univ., St. Louis, MO (United States)

2015-01-29

The potential for developing commercially viable microbial H₂-production systems as a renewable source of biofuel has been limited by the need for an anaerobic environment to enable photobiological H₂-production in capable bacterial and algal species. In this project, we have shown that the cyanobacterium Cyanothece sp. ATCC 51142 has the capacity for highly efficient H₂-production under natural aerobic conditions. The marine cyanobacterium Cyanothece sp. ATCC 51142 has a diurnal metabolic cycle; photosynthesis and carbon fixation occur during daylight hours and then at night, high rates of respiration create a suboxic intracellular environment that enables O₂-sensitive processes to occur, including N2-fixation and H₂-production. We developed a two-stage approach to monitor H₂-production by Cyanothece 51142. In the first stage, we grew the bacteria aerobically in an alternating 12 hour light/dark cycle. A second ‘incubation’ stage was then carried out in which we took cells from the end of a 12 hour light growth period and incubated them in air-tight vials for a further 12 hours under continuous illumination. Analysis of the headspace in the vial revealed high specific rates of H₂-production (>150 μmol of H₂ per mg chlorophyll per hour) during this incubation period. Furthermore, the rate of H₂-production could be enhanced by growing the cells in the presence of high levels of CO₂ or glycerol. We also confirmed that H₂-production was mediated by the nitrogenase system found in these Cyanothece cells. Interestingly, in the absence of molecular N₂, nitrogenase systems channel all available electrons towards H₂-production. Accordingly, when we incubated glycerol-supplemented Cyanothece 51142 cells in the absence of N₂, the rate of H₂-production increased up to 467 μmol of H₂ per mg

The effect of elevated CO{sub 2} concentration on photosynthesis of Sphagnum fuscum

Energy Technology Data Exchange (ETDEWEB)

Jauhiainen, J; Silvola, J [Joensuu Univ. (Finland). Dept. of Biology

1997-12-31

The objectives of the research were to measure photosynthesis of Sphagnum fuscum in long term exposure to four CO{sub 2} levels at semi-natural conditions, to find out if there is an acclimation of net photosynthesis into prevailing CO{sub 2} concentrations and to measure the moisture dependent net photosynthesis at various CO{sub 2} concentrations of samples grown at different CO{sub 2} concentrations

The effect of elevated CO{sub 2} concentration on photosynthesis of Sphagnum fuscum

Energy Technology Data Exchange (ETDEWEB)

Jauhiainen, J.; Silvola, J. [Joensuu Univ. (Finland). Dept. of Biology

1996-12-31

The objectives of the research were to measure photosynthesis of Sphagnum fuscum in long term exposure to four CO{sub 2} levels at semi-natural conditions, to find out if there is an acclimation of net photosynthesis into prevailing CO{sub 2} concentrations and to measure the moisture dependent net photosynthesis at various CO{sub 2} concentrations of samples grown at different CO{sub 2} concentrations

Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Velasco, Mayda [Northwestern University

2013-11-01

This work is focused on the design and construction of novel beam diagnostic and instrumentation for charged particle accelerators required for the next generation of linear colliders. Our main interest is in non-invasive techniques. The Northwestern group of Velasco has been a member of the CLIC Test Facility 3 (CTF3) collaboration since 2003, and the beam instrumentation work is developed mostly at this facility1. This 4 kW electron beam facility has a 25-170 MeV electron LINAC. CTF3 performed a set of dedicated measurements to finalize the development of our RF-Pickup bunch length detectors. The RF-pickup based on mixers was fully commissioned in 2009 and the RF-pickup based on diodes was finished in time for the 2010-11 data taking. The analysis of all the data taken in by the summer of 2010 was finish in time and presented at the main conference of the year, LINAC 2010 in Japan.

A quantum protective mechanism in photosynthesis

NARCIS (Netherlands)

Marais, A.; Sinayskiy, I.; Petruccione, F.; van Grondelle, R.

2015-01-01

Since the emergence of oxygenic photosynthesis, living systems have developed protective mechanisms against reactive oxygen species. During charge separation in photosynthetic reaction centres, triplet states can react with molecular oxygen generating destructive singlet oxygen. The triplet product

State child health; revisions to the regulations implementing the State Children's Health Insurance Program. Interim final rule with comment period; revisions, delay of effective date, and technical amendments to final rule.

Science.gov (United States)

2001-06-25

Title XXI authorizes the State Children's Health Insurance Program (SCHIP) to assist State efforts to initiate and expand the provision of child health assistance to uninsured, low-income children. On January 11, 2001 we published a final rule in the Federal Register to implement SCHIP that has not gone into effect. This interim final rule further delays the effective date, revises certain provisions and solicits public comment, and makes technical corrections and clarifications to the January 2001 final rule based on further review of the comments received and applicable law. Only the provisions set forth in this document have changed. All other provisions set forth in the January 2001 final rule will be implemented without change.

Major alterations in transcript profiles between C3-C4 and C4 photosynthesis of an amphibious species Eleocharis baldwinii.

Science.gov (United States)

Chen, Taiyu; Zhu, Xin-Guang; Lin, Yongjun

2014-09-01

Engineering C4 photosynthetic metabolism into C3 crops is regarded as a major strategy to increase crop productivity, and clarification of the evolutionary processes of C4 photosynthesis can help the better use of this strategy. Here, Eleocharis baldwinii, a species in which C4 photosynthesis can be induced from a C3-C4 state under either environmental or ABA treatments, was used to identify the major transcriptional modifications during the process from C3-C4 to C4. The transcriptomic comparison suggested that in addition to the major differences in C4 core pathway, the pathways of glycolysis, citrate acid metabolism and protein synthesis were dramatically modified during the inducement of C4 photosynthetic states. Transcripts of many transporters, including not only metabolite transporters but also ion transporters, were dramatically increased in C4 photosynthetic state. Many candidate regulatory genes with unidentified functions were differentially expressed in C3-C4 and C4 photosynthetic states. Finally, it was indicated that ABA, auxin signaling and DNA methylation play critical roles in the regulation of C4 photosynthesis. In summary, by studying the different photosynthetic states of the same species, this work provides the major transcriptional differences between C3-C4 and C4 photosynthesis, and many of the transcriptional differences are potentially related to C4 development and therefore are the potential targets for reverse genetics studies.

Final priority. Rehabilitation Training: Job-Driven Vocational Rehabilitation Technical Assistance Center. Final priority.

Science.gov (United States)

2014-08-19

The Assistant Secretary for Special Education and Rehabilitative Services announces a priority under the Rehabilitation Training program to establish a Job-Driven Vocational Rehabilitation Technical Assistance Center (JDVRTAC). The Assistant Secretary may use this priority for competitions in fiscal year (FY) 2014 and later years. We take this action to focus on training in an area of national need. Specifically, this priority responds to the Presidential Memorandum to Federal agencies directing them to take action to address job-driven training for the Nation's workers. The JDVRTAC will provide technical assistance (TA) to State vocational rehabilitation (VR) agencies to help them develop for individuals with disabilities training and employment opportunities that meet the needs of today's employers.

Final priority; Technical Assistance on State Data Collection--IDEA Data Management Center. Final priority.

Science.gov (United States)

2014-08-05

The Assistant Secretary for the Office of Special Education and Rehabilitative Services (OSERS) announces a priority under the Technical Assistance on State Data Collection program. The Assistant Secretary may use this priority for competitions in fiscal year (FY) 2014 and later years. We take this action to fund a cooperative agreement to establish and operate an IDEA Data Management Center (Center) that will provide technical assistance (TA) to improve the capacity of States to meet the data collection requirements of the Individuals with Disabilities Education Act (IDEA).

Next Generation Nuclear Plant (NGNP) Prismatic HTGR Conceptual Design Project - Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Saurwein, John

2011-07-15

This report is the Final Technical Report for the Next Generation Nuclear Plant (NGNP) Prismatic HTGR Conceptual Design Project conducted by a team led by General Atomics under DOE Award DE-NE0000245. The primary overall objective of the project was to develop and document a conceptual design for the Steam Cycle Modular Helium Reactor (SC-MHR), which is the reactor concept proposed by General Atomics for the NGNP Demonstration Plant. The report summarizes the project activities over the entire funding period, compares the accomplishments with the goals and objectives of the project, and discusses the benefits of the work. The report provides complete listings of the products developed under the award and the key documents delivered to the DOE.

Next Generation Nuclear Plant (NGNP) Prismatic HTGR Conceptual Design Project - Final Technical Report

International Nuclear Information System (INIS)

Saurwein, J.

2011-01-01

This report is the Final Technical Report for the Next Generation Nuclear Plant (NGNP) Prismatic HTGR Conceptual Design Project conducted by a team led by General Atomics under DOE Award DE-NE0000245. The primary overall objective of the project was to develop and document a conceptual design for the Steam Cycle Modular Helium Reactor (SC-MHR), which is the reactor concept proposed by General Atomics for the NGNP Demonstration Plant. The report summarizes the project activities over the entire funding period, compares the accomplishments with the goals and objectives of the project, and discusses the benefits of the work. The report provides complete listings of the products developed under the award and the key documents delivered to the DOE.

Association genetics and transcriptome analysis reveal a gibberellin-responsive pathway involved in regulating photosynthesis.

Science.gov (United States)

Xie, Jianbo; Tian, Jiaxing; Du, Qingzhang; Chen, Jinhui; Li, Ying; Yang, Xiaohui; Li, Bailian; Zhang, Deqiang

2016-05-01

Gibberellins (GAs) regulate a wide range of important processes in plant growth and development, including photosynthesis. However, the mechanism by which GAs regulate photosynthesis remains to be understood. Here, we used multi-gene association to investigate the effect of genes in the GA-responsive pathway, as constructed by RNA sequencing, on photosynthesis, growth, and wood property traits, in a population of 435 Populus tomentosa By analyzing changes in the transcriptome following GA treatment, we identified many key photosynthetic genes, in agreement with the observed increase in measurements of photosynthesis. Regulatory motif enrichment analysis revealed that 37 differentially expressed genes related to photosynthesis shared two essential GA-related cis-regulatory elements, the GA response element and the pyrimidine box. Thus, we constructed a GA-responsive pathway consisting of 47 genes involved in regulating photosynthesis, including GID1, RGA, GID2, MYBGa, and 37 photosynthetic differentially expressed genes. Single nucleotide polymorphism (SNP)-based association analysis showed that 142 SNPs, representing 40 candidate genes in this pathway, were significantly associated with photosynthesis, growth, and wood property traits. Epistasis analysis uncovered interactions between 310 SNP-SNP pairs from 37 genes in this pathway, revealing possible genetic interactions. Moreover, a structural gene-gene matrix based on a time-course of transcript abundances provided a better understanding of the multi-gene pathway affecting photosynthesis. The results imply a functional role for these genes in mediating photosynthesis, growth, and wood properties, demonstrating the potential of combining transcriptome-based regulatory pathway construction and genetic association approaches to detect the complex genetic networks underlying quantitative traits. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights

Imagining Technicities

DEFF Research Database (Denmark)

Liboriussen, Bjarke; Plesner, Ursula

2011-01-01

to the elements of taste and skill. In the final analysis those references were synthesized as five imagined technicities: the architect, the engineer, the client, the Chinese, and the Virtual World native. Because technicities are often assumed and rarely discussed as actants who influence practice, their role......, this article focuses on innovative uses of virtual worlds in architecture. We interviewed architects, industrial designers and other practitioners. Conceptually supported by an understanding of technicity found in Cultural Studies, the interviews were then coded with a focus on interviewees’ references...... in cooperation and development of ICTs seems to pass unnoticed. However, since they are aligned into ICTs, technicities impact innovation....

2011 Photosynthesis Gordon Research Conference & Seminar (June 11-17, 2011, Davidson College, Davidson, North Carolina)

Energy Technology Data Exchange (ETDEWEB)

Prof. Krishna Niyogi

2011-06-17

Photosynthesis is the biological process that converts solar energy into chemical energy. Elucidation of the mechanisms of photosynthetic energy conversion at a molecular level is fundamentally important for understanding the biology of photosynthetic organisms, for optimizing biological solar fuels production, and for developing biologically inspired approaches to solar energy conversion. The 2011 Gordon Conference on Photosynthesis will present cutting-edge research focusing on the biochemical aspects of photosynthesis, including: (1) structure, assembly, and function of photosynthetic complexes; (2) the mechanism of water splitting by PSII; (3) light harvesting and quenching; (4) alternative electron transport pathways; (5) biosynthesis of pigments and cofactors; and (6) improvement of photosynthesis for bioenergy and food production. Reflecting the interdisciplinary nature of photosynthesis research, a diverse group of invited speakers will represent a variety of scientific approaches to investigate photosynthesis, such as biochemistry, molecular genetics, structural biology, systems biology, and spectroscopy. Highly interactive poster sessions provide opportunities for graduate students and postdocs to present their work and exchange ideas with leaders in the field. One of the highlights of the Conference is a session featuring short talks by junior investigators selected from the poster presentations. The collegial atmosphere of the Photosynthesis GRC, with programmed discussion sessions as well as informal gatherings in the afternoons and evenings, enables participants to brainstorm, exchange ideas, and forge new collaborations. For the second time, this Conference will be immediately preceded by a Gordon Research Seminar on Photosynthesis (June 11-12, 2011, at the same location), with a focus on 'Photosynthesis, Bioenergy, and the Environment.' The GRS provides an additional opportunity for graduate students and postdocs to present their research

Effect of Bradyrhizobium photosynthesis on stem nodulation of Aeschynomene sensitiva

OpenAIRE

Giraud, Eric; Hannibal, Laure; Fardoux, Joël; Verméglio, A.; Dreyfus, Bernard

2000-01-01

Some leguminous species of the genus #Aeschynomene$ are specifically stem-nodulated by photosynthetic bradyrhizobia. To study the effect of bacterial photosynthesis during symbiosis, we generated a photosynthesis-negative mutant of the #Bradyrhizobium$ sp. strain ORS278 symbiont of #Aeschynomene sensitiva$. The presence of a functional photosynthetic unit in bacterioids and the high expression of the photosynthetic genes observed in stem nodules demonstrate that the bacteria are photosyntheti...

Estimating Photosynthetic Radiation Use Efficiency Using Incident Light and Photosynthesis of Individual Leaves

OpenAIRE

ROSATI, A.; DEJONG, T. M.

2003-01-01

It has been theorized that photosynthetic radiation use efficiency (PhRUE) over the course of a day is constant for leaves throughout a canopy if leaf nitrogen content and photosynthetic properties are adapted to local light so that canopy photosynthesis over a day is optimized. To test this hypothesis, ‘daily’ photosynthesis of individual leaves of Solanum melongena plants was calculated from instantaneous rates of photosynthesis integrated over the daylight hours. Instantaneous photosynthes...

Leaf area and net photosynthesis during development of Prunus serotina seedlings

Science.gov (United States)

Stephen B. Horsley; Kurt W. Gottschalk

1993-01-01

We used the plastochron index to study the relationship between plant age, leaf age and development, and net photosynthesis of black cherry (Prtmus serotina Ehrh.) seedlings. Leaf area and net photosynthesis were measured on all leaves >=75 mm of plants ranging in age from 7 to 20 plastochrons. Effects of plant developmental stage...

Redesigning photosynthesis to sustainably meet global food and bioenergy demand

Science.gov (United States)

Ort, Donald R.; Merchant, Sabeeha S.; Alric, Jean; Barkan, Alice; Blankenship, Robert E.; Bock, Ralph; Croce, Roberta; Hanson, Maureen R.; Hibberd, Julian M.; Long, Stephen P.; Moore, Thomas A.; Moroney, James; Niyogi, Krishna K.; Parry, Martin A. J.; Peralta-Yahya, Pamela P.; Prince, Roger C.; Redding, Kevin E.; Spalding, Martin H.; van Wijk, Klaas J.; Vermaas, Wim F. J.; von Caemmerer, Susanne; Weber, Andreas P. M.; Yeates, Todd O.; Yuan, Joshua S.; Zhu, Xin Guang

2015-01-01

The world’s crop productivity is stagnating whereas population growth, rising affluence, and mandates for biofuels put increasing demands on agriculture. Meanwhile, demand for increasing cropland competes with equally crucial global sustainability and environmental protection needs. Addressing this looming agricultural crisis will be one of our greatest scientific challenges in the coming decades, and success will require substantial improvements at many levels. We assert that increasing the efficiency and productivity of photosynthesis in crop plants will be essential if this grand challenge is to be met. Here, we explore an array of prospective redesigns of plant systems at various scales, all aimed at increasing crop yields through improved photosynthetic efficiency and performance. Prospects range from straightforward alterations, already supported by preliminary evidence of feasibility, to substantial redesigns that are currently only conceptual, but that may be enabled by new developments in synthetic biology. Although some proposed redesigns are certain to face obstacles that will require alternate routes, the efforts should lead to new discoveries and technical advances with important impacts on the global problem of crop productivity and bioenergy production. PMID:26124102

Effects of high CO2 levels on dynamic photosynthesis: carbon gain, mechanisms, and environmental interactions.

Science.gov (United States)

Tomimatsu, Hajime; Tang, Yanhong

2016-05-01

Understanding the photosynthetic responses of terrestrial plants to environments with high levels of CO2 is essential to address the ecological effects of elevated atmospheric CO2. Most photosynthetic models used for global carbon issues are based on steady-state photosynthesis, whereby photosynthesis is measured under constant environmental conditions; however, terrestrial plant photosynthesis under natural conditions is highly dynamic, and photosynthetic rates change in response to rapid changes in environmental factors. To predict future contributions of photosynthesis to the global carbon cycle, it is necessary to understand the dynamic nature of photosynthesis in relation to high CO2 levels. In this review, we summarize the current body of knowledge on the photosynthetic response to changes in light intensity under experimentally elevated CO2 conditions. We found that short-term exposure to high CO2 enhances photosynthetic rate, reduces photosynthetic induction time, and reduces post-illumination CO2 burst, resulting in increased leaf carbon gain during dynamic photosynthesis. However, long-term exposure to high CO2 during plant growth has varying effects on dynamic photosynthesis. High levels of CO2 increase the carbon gain in photosynthetic induction in some species, but have no significant effects in other species. Some studies have shown that high CO2 levels reduce the biochemical limitation on RuBP regeneration and Rubisco activation during photosynthetic induction, whereas the effects of high levels of CO2 on stomatal conductance differ among species. Few studies have examined the influence of environmental factors on effects of high levels of CO2 on dynamic photosynthesis. We identified several knowledge gaps that should be addressed to aid future predictions of photosynthesis in high-CO2 environments.

Broad-Scale Comparison of Photosynthesis in Terrestrial and Aquatic Plant Communities

DEFF Research Database (Denmark)

Sand-Jensen, Kaj; Krause-Jensen, D.

1997-01-01

Comparisons of photosynthesis in terrestrial and aquatic habitats have been impaired by differences in methods and time-scales of measurements. We compiled information on gross photosynthesis at high irradiance and photosynthetic efficiency at low irradiance from 109 published terrestrial studies...... communities probably due to more efficient light utilization and gas exchange in the terrestrial habitats. By contrast only small differences were found within different aquatic plant communities or within different terrestrial plant communities....... of forests, grasslands and crops and 319 aquatic studies of phytoplankton, macrophyte and attached microalgal communities to test if specific differences existed between the communities. Maximum gross photosynthesis and photosynthetic efficiency were systematically higher in terrestrial than in aquatic...

Shedding light on the role of photosynthesis in pathogen colonization and host defense

KAUST Repository

Garavaglia, Betiana S.; Thomas, Ludivine; Gottig, Natalia; Zimaro, Tamara; Garofalo, Cecilia G.; Gehring, Christoph A; Ottado, Jorgelina

2010-01-01

The role of photosynthesis in plant defense is a fundamental question awaiting further molecular and physiological elucidation. To this end we investigated host responses to infection with the bacterial pathogen Xanthomonas axonopodis pv. citri, the pathogen responsible for citrus canker. This pathogen encodes a plant-like natriuretic peptide (XacPNP) that is expressed specifically during the infection process and prevents deterioration of the physiological condition of the infected tissue. Proteomic assays of citrus leaves infected with a XacPNP deletion mutant (DeltaXacPNP) resulted in a major reduction in photosynthetic proteins such as Rubisco, Rubisco activase and ATP synthase as a compared with infection with wild type bacteria. In contrast, infiltration of citrus leaves with recombinant XacPNP caused an increase in these host proteins and a concomitant increase in photosynthetic efficiency as measured by chlorophyll fluorescence assays. Reversion of the reduction in photosynthetic efficiency in citrus leaves infected with DeltaXacPNP was achieved by the application of XacPNP or Citrus sinensis PNP lending support to a case of molecular mimicry. Finally, given that DeltaXacPNP infection is less successful than infection with the wild type, it appears that reducing photosynthesis is an effective plant defense mechanism against biotrophic pathogens.

Shedding light on the role of photosynthesis in pathogen colonization and host defense

KAUST Repository

Garavaglia, Betiana S.

2010-09-01

The role of photosynthesis in plant defense is a fundamental question awaiting further molecular and physiological elucidation. To this end we investigated host responses to infection with the bacterial pathogen Xanthomonas axonopodis pv. citri, the pathogen responsible for citrus canker. This pathogen encodes a plant-like natriuretic peptide (XacPNP) that is expressed specifically during the infection process and prevents deterioration of the physiological condition of the infected tissue. Proteomic assays of citrus leaves infected with a XacPNP deletion mutant (DeltaXacPNP) resulted in a major reduction in photosynthetic proteins such as Rubisco, Rubisco activase and ATP synthase as a compared with infection with wild type bacteria. In contrast, infiltration of citrus leaves with recombinant XacPNP caused an increase in these host proteins and a concomitant increase in photosynthetic efficiency as measured by chlorophyll fluorescence assays. Reversion of the reduction in photosynthetic efficiency in citrus leaves infected with DeltaXacPNP was achieved by the application of XacPNP or Citrus sinensis PNP lending support to a case of molecular mimicry. Finally, given that DeltaXacPNP infection is less successful than infection with the wild type, it appears that reducing photosynthesis is an effective plant defense mechanism against biotrophic pathogens.

Recovery of Cymodocea nodosa (Ucria Ascherson photosynthesis after a four-month dark period

Directory of Open Access Journals (Sweden)

Erik-Jan Malta

2006-09-01

Full Text Available P align=justify>Cymodocea nodosa plants were dark incubated for four months. The potential of reactivating photosynthesis was tested in an experiment in which half of the plants were reilluminated (HL while the other half were grown under very low irradiance levels (LL. Photosynthesis was measured using PAM fluorescence and tissue nutrient and carbohydrate contents were analysed. Photosynthetic efficiency (Fv/Fm in HL plants increased from 0 to 0.58, whereas LL plants remained inactive. Photosynthetic parameters also increased, resulting in a final Ik of 97.5 µmol m-2 s-1. Leaf shedding led to a negative mean RGR in HL plants. Tissue C and N dropped considerably during dark incubation in both rhizomes and shoots. Starch content was nearly equal for rhizomes and shoots (4.3 mg /g DW and was not affected by dark incubation. In contrast, sucrose content dropped from 40.0 mg /g DW to zero in shoots and from 240 to 40.0 mg /g DW in rhizomes in HL plants. We conclude that C. nodosa is capable of recovering photosynthetic activity after four months darkness, which is considerably longer than the 80 d recorded so far for a seagrass. Stored carbohydrates, more specifically sucrose, play an important role in both survival and reactivation.

Seasonality of temperate forest photosynthesis and daytime respiration.

Science.gov (United States)

Wehr, R; Munger, J W; McManus, J B; Nelson, D D; Zahniser, M S; Davidson, E A; Wofsy, S C; Saleska, S R

2016-06-30

Terrestrial ecosystems currently offset one-quarter of anthropogenic carbon dioxide (CO2) emissions because of a slight imbalance between global terrestrial photosynthesis and respiration. Understanding what controls these two biological fluxes is therefore crucial to predicting climate change. Yet there is no way of directly measuring the photosynthesis or daytime respiration of a whole ecosystem of interacting organisms; instead, these fluxes are generally inferred from measurements of net ecosystem-atmosphere CO2 exchange (NEE), in a way that is based on assumed ecosystem-scale responses to the environment. The consequent view of temperate deciduous forests (an important CO2 sink) is that, first, ecosystem respiration is greater during the day than at night; and second, ecosystem photosynthetic light-use efficiency peaks after leaf expansion in spring and then declines, presumably because of leaf ageing or water stress. This view has underlain the development of terrestrial biosphere models used in climate prediction and of remote sensing indices of global biosphere productivity. Here, we use new isotopic instrumentation to determine ecosystem photosynthesis and daytime respiration in a temperate deciduous forest over a three-year period. We find that ecosystem respiration is lower during the day than at night-the first robust evidence of the inhibition of leaf respiration by light at the ecosystem scale. Because they do not capture this effect, standard approaches overestimate ecosystem photosynthesis and daytime respiration in the first half of the growing season at our site, and inaccurately portray ecosystem photosynthetic light-use efficiency. These findings revise our understanding of forest-atmosphere carbon exchange, and provide a basis for investigating how leaf-level physiological dynamics manifest at the canopy scale in other ecosystems.

Invitation to the 17th international congress on photosynthesis research in 2016 : photosynthesis in a changing world

NARCIS (Netherlands)

van Amerongen, Herbert; Croce, Roberta

2016-01-01

The 17th International Congress on Photosynthesis will be held from August 7 to 12, 2016 in Maastricht, The Netherlands. The congress will include an opening reception, 15 plenary lectures, 28 scientific symposia, many poster sessions, displays by scientific companies, excursions, congress dinner,

PHOTOSYNTHESIS AT THE FOREFRONT OF A SUSTAINABLE LIFE

Directory of Open Access Journals (Sweden)

Paul J.D. Janssen

2014-06-01

Full Text Available The development of a sustainable bio-based economy has drawn much attention in recent years, and research to find smart solutions to the many inherent challenges has intensified. In nature, perhaps the best example of an authentic sustainable system is oxygenic photosynthesis. The biochemistry of this intricate process is empowered by solar radiation influx and performed by hierarchically organized complexes composed by photoreceptors, inorganic catalysts, and enzymes which define specific niches for optimizing light-to-energy conversion. The success of this process relies on its capability to exploit the almost inexhaustible reservoirs of sunlight, water, and carbon dioxide to transform photonic energy into chemical energy such as stored in adenosine triphosphate. Oxygenic photosynthesis is responsible for most of the oxygen, fossil fuels, and biomass on our planet. So, even after a few billion years of evolution, this process unceasingly supports life on earth, and probably soon also in outer-space, and inspires the development of enabling technologies for a sustainable global economy and ecosystem. The following review covers some of the major milestones reached in photosynthesis research, each reflecting lasting routes of innovation in agriculture, environmental protection, and clean energy production.

Inhibition of photosynthesis and bleaching of zooxanthellae by the coral pathogen Vibrio shiloi.

Science.gov (United States)

Ben-Haim, Y; Banim, E; Kushmaro, A; Loya, Y; Rosenberg, E

1999-06-01

Vibrio shiloi is the causative agent of bleaching (loss of endosymbiotic zooxanthellae) of the coral Oculina patagonica in the Mediterranean Sea. To obtain information on the mechanism of bleaching, we examined the effect of secreted material (AK1-S) produced by V. shiloi on zooxanthellae isolated from corals. AK1-S caused a rapid inhibition of photosynthesis of the algae, as measured with a Mini-PAM fluorometer. The inhibition of photosynthesis was caused by (i) ammonia produced during the growth of V. shiloi on protein-containing media and (ii) a non-dialysable heat-resistant factor. This latter material did not inhibit photosynthesis of the algae by itself but, when added to different concentrations of NH4Cl, enhanced the inhibition approximately two- to threefold. Ammonia and the enhancer were effective to different degrees on zooxanthellae isolated from four species of coral examined. In addition to the rapid inhibition of photosynthesis, AK1-S caused bleaching (loss of pigmentation) and lysis of zooxanthellae. Bleaching was more rapid than lysis, reaching a peak (25% bleached algae) after 6 h. The factors in AK1-S responsible for bleaching and lysis were different from those responsible for the inhibition of photosynthesis, because they were heat sensitive, non-dialysable and active in the dark. Thus, the coral pathogen V. shiloi produces an array of extracellular materials that can inhibit photosynthesis, bleach and lyse zooxanthellae.

Canopy Photosynthesis: From Basics to Applications

NARCIS (Netherlands)

Hikosaka, Kouki; Niinemets, Ülo; Anten, N.P.R.

2016-01-01

A plant canopy, a collection of leaves, is an ecosystem-level unit of photosynthesis that assimilates carbon dioxide and exchanges other gases and energy with the atmosphere in a manner highly sensitive to ambient conditions including atmospheric carbon dioxide and water vapor concentrations, light

A Forgotten Application of the Starch Test: C[subscript 4] Photosynthesis

Science.gov (United States)

Harley, Suzanne M.

2013-01-01

In many labs on photosynthesis, the presence of starch in leaves is used as an indirect indicator of photosynthetic activity. Students do starch tests on leaves from plants that have been kept under a variety of conditions in order to check parameters for photosynthesis. The starch test can also be used to enable students to discover differences…

Phenotypic engineering of photosynthesis related traits in Arabidopsis thaliana using genome interrogation

NARCIS (Netherlands)

Tol, Niels van

2016-01-01

Photosynthesis is the process that harvests energy from light, and fixes it as chemical energy. It is performed by cyanobacteria, algae, and plants. The overall solar energy to biomass conversion efficiency of plant photosynthesis is widely considered to be very low. Recent models have indicated

Connecting Biochemical Photosynthesis Models with Crop Models to Support Crop Improvement.

Science.gov (United States)

Wu, Alex; Song, Youhong; van Oosterom, Erik J; Hammer, Graeme L

2016-01-01

The next advance in field crop productivity will likely need to come from improving crop use efficiency of resources (e.g., light, water, and nitrogen), aspects of which are closely linked with overall crop photosynthetic efficiency. Progress in genetic manipulation of photosynthesis is confounded by uncertainties of consequences at crop level because of difficulties connecting across scales. Crop growth and development simulation models that integrate across biological levels of organization and use a gene-to-phenotype modeling approach may present a way forward. There has been a long history of development of crop models capable of simulating dynamics of crop physiological attributes. Many crop models incorporate canopy photosynthesis (source) as a key driver for crop growth, while others derive crop growth from the balance between source- and sink-limitations. Modeling leaf photosynthesis has progressed from empirical modeling via light response curves to a more mechanistic basis, having clearer links to the underlying biochemical processes of photosynthesis. Cross-scale modeling that connects models at the biochemical and crop levels and utilizes developments in upscaling leaf-level models to canopy models has the potential to bridge the gap between photosynthetic manipulation at the biochemical level and its consequences on crop productivity. Here we review approaches to this emerging cross-scale modeling framework and reinforce the need for connections across levels of modeling. Further, we propose strategies for connecting biochemical models of photosynthesis into the cross-scale modeling framework to support crop improvement through photosynthetic manipulation.

Connecting Biochemical Photosynthesis Models with Crop Models to Support Crop Improvement

Science.gov (United States)

Wu, Alex; Song, Youhong; van Oosterom, Erik J.; Hammer, Graeme L.

2016-01-01

The next advance in field crop productivity will likely need to come from improving crop use efficiency of resources (e.g., light, water, and nitrogen), aspects of which are closely linked with overall crop photosynthetic efficiency. Progress in genetic manipulation of photosynthesis is confounded by uncertainties of consequences at crop level because of difficulties connecting across scales. Crop growth and development simulation models that integrate across biological levels of organization and use a gene-to-phenotype modeling approach may present a way forward. There has been a long history of development of crop models capable of simulating dynamics of crop physiological attributes. Many crop models incorporate canopy photosynthesis (source) as a key driver for crop growth, while others derive crop growth from the balance between source- and sink-limitations. Modeling leaf photosynthesis has progressed from empirical modeling via light response curves to a more mechanistic basis, having clearer links to the underlying biochemical processes of photosynthesis. Cross-scale modeling that connects models at the biochemical and crop levels and utilizes developments in upscaling leaf-level models to canopy models has the potential to bridge the gap between photosynthetic manipulation at the biochemical level and its consequences on crop productivity. Here we review approaches to this emerging cross-scale modeling framework and reinforce the need for connections across levels of modeling. Further, we propose strategies for connecting biochemical models of photosynthesis into the cross-scale modeling framework to support crop improvement through photosynthetic manipulation. PMID:27790232

Cyanobacteria as an Experimental Platform for Modifying Bacterial and Plant Photosynthesis

Energy Technology Data Exchange (ETDEWEB)

Jensen, Poul Erik [Copenhagen Plant Science Center (CPSC), Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen (Denmark); Leister, Dario, E-mail: leister@lmu.de [Copenhagen Plant Science Center (CPSC), Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen (Denmark); Plant Molecular Biology (Botany), Department of Biology I, Ludwig-Maximilians-University Munich, Munich (Germany)

2014-04-21

One of the fascinating characteristics of photosynthesis is its capacity for repair, self-renewal, and energy storage within chemical bonds. Given the evolutionary history of plant photosynthesis and the patchwork nature of many of its components, it is safe to assume that the light reactions of plant photosynthesis can be improved by genetic engineering (Leister, 2012). The evolutionary precursor of chloroplasts was a microorganism whose biochemistry was very similar to that of present-day cyanobacteria. Many cyanobacterial species are easy to manipulate genetically and grow robustly in liquid cultures that can be easily scaled up into photobioreactors. Therefore, cyanobacteria such as Synechocystis sp. PCC 6803 (hereafter “Synechocystis”) have widely been used for decades as model systems to study the principles of photosynthesis (Table 1). Indeed, genetic engineering based on homologous recombination is well-established in Synechocystis. Moreover, new genetic engineering toolkits, including marker-less gene deletion and replacement strategies needing only a single transformation step (Viola et al., 2014) and novel approaches for chromosomal integration and expression of synthetic gene operons (Bentley et al., 2014), allow for large-scale replacement and/or integration of dozens of genes in reasonable time frames. This makes Synechocystis a very attractive basis for the experimental modification of important processes like photosynthesis, and it also suggests innovative ways of improving modules of related eukaryotic pathways, among them the combination of cyanobacterial and eukaryotic elements using the tools of synthetic biology.

Cyanobacteria as an Experimental Platform for Modifying Bacterial and Plant Photosynthesis

International Nuclear Information System (INIS)

Jensen, Poul Erik; Leister, Dario

2014-01-01

One of the fascinating characteristics of photosynthesis is its capacity for repair, self-renewal, and energy storage within chemical bonds. Given the evolutionary history of plant photosynthesis and the patchwork nature of many of its components, it is safe to assume that the light reactions of plant photosynthesis can be improved by genetic engineering (Leister, 2012). The evolutionary precursor of chloroplasts was a microorganism whose biochemistry was very similar to that of present-day cyanobacteria. Many cyanobacterial species are easy to manipulate genetically and grow robustly in liquid cultures that can be easily scaled up into photobioreactors. Therefore, cyanobacteria such as Synechocystis sp. PCC 6803 (hereafter “Synechocystis”) have widely been used for decades as model systems to study the principles of photosynthesis (Table 1). Indeed, genetic engineering based on homologous recombination is well-established in Synechocystis. Moreover, new genetic engineering toolkits, including marker-less gene deletion and replacement strategies needing only a single transformation step (Viola et al., 2014) and novel approaches for chromosomal integration and expression of synthetic gene operons (Bentley et al., 2014), allow for large-scale replacement and/or integration of dozens of genes in reasonable time frames. This makes Synechocystis a very attractive basis for the experimental modification of important processes like photosynthesis, and it also suggests innovative ways of improving modules of related eukaryotic pathways, among them the combination of cyanobacterial and eukaryotic elements using the tools of synthetic biology.

Uncertainty Quantification in the Reliability and Risk Assessment of Generation IV Reactors: Final Scientific/Technical Report

International Nuclear Information System (INIS)

Vierow, Karen; Aldemir, Tunc

2009-01-01

The project entitled, 'Uncertainty Quantification in the Reliability and Risk Assessment of Generation IV Reactors', was conducted as a DOE NERI project collaboration between Texas A and M University and The Ohio State University between March 2006 and June 2009. The overall goal of the proposed project was to develop practical approaches and tools by which dynamic reliability and risk assessment techniques can be used to augment the uncertainty quantification process in probabilistic risk assessment (PRA) methods and PRA applications for Generation IV reactors. This report is the Final Scientific/Technical Report summarizing the project.

Uncertainty Quantification in the Reliability and Risk Assessment of Generation IV Reactors: Final Scientific/Technical Report

Energy Technology Data Exchange (ETDEWEB)

Vierow, Karen; Aldemir, Tunc

2009-09-10

The project entitled, “Uncertainty Quantification in the Reliability and Risk Assessment of Generation IV Reactors”, was conducted as a DOE NERI project collaboration between Texas A&M University and The Ohio State University between March 2006 and June 2009. The overall goal of the proposed project was to develop practical approaches and tools by which dynamic reliability and risk assessment techniques can be used to augment the uncertainty quantification process in probabilistic risk assessment (PRA) methods and PRA applications for Generation IV reactors. This report is the Final Scientific/Technical Report summarizing the project.

Chlorophyll Can Be Reduced in Crop Canopies with Little Penalty to Photosynthesis1[OPEN

Science.gov (United States)

Drewry, Darren T.; VanLoocke, Andy; Cho, Young B.

2018-01-01

The hypothesis that reducing chlorophyll content (Chl) can increase canopy photosynthesis in soybeans was tested using an advanced model of canopy photosynthesis. The relationship among leaf Chl, leaf optical properties, and photosynthetic biochemical capacity was measured in 67 soybean (Glycine max) accessions showing large variation in leaf Chl. These relationships were integrated into a biophysical model of canopy-scale photosynthesis to simulate the intercanopy light environment and carbon assimilation capacity of canopies with wild type, a Chl-deficient mutant (Y11y11), and 67 other mutants spanning the extremes of Chl to quantify the impact of variation in leaf-level Chl on canopy-scale photosynthetic assimilation and identify possible opportunities for improving canopy photosynthesis through Chl reduction. These simulations demonstrate that canopy photosynthesis should not increase with Chl reduction due to increases in leaf reflectance and nonoptimal distribution of canopy nitrogen. However, similar rates of canopy photosynthesis can be maintained with a 9% savings in leaf nitrogen resulting from decreased Chl. Additionally, analysis of these simulations indicate that the inability of Chl reductions to increase photosynthesis arises primarily from the connection between Chl and leaf reflectance and secondarily from the mismatch between the vertical distribution of leaf nitrogen and the light absorption profile. These simulations suggest that future work should explore the possibility of using reduced Chl to improve canopy performance by adapting the distribution of the “saved” nitrogen within the canopy to take greater advantage of the more deeply penetrating light. PMID:29061904

When growth and photosynthesis don't match: implications for carbon balance models

Science.gov (United States)

Medlyn, B.; Mahmud, K.; Duursma, R.; Pfautsch, S.; Campany, C.

2017-12-01

Most models of terrestrial plant growth are based on the principle of carbon balance: that growth can be predicted from net uptake of carbon via photosynthesis. A key criticism leveled at these models by plant physiologists is that there are many circumstances in which plant growth appears to be independent of photosynthesis: for example, during the onset of drought, or with rising atmospheric CO2 concentration. A crucial problem for terrestrial carbon cycle models is to develop better representations of plant carbon balance when there is a mismatch between growth and photosynthesis. Here we present two studies providing insight into this mismatch. In the first, effects of root restriction on plant growth were examined by comparing Eucalyptus tereticornis seedlings growing in containers of varying sizes with freely-rooted seedlings. Root restriction caused a reduction in photosynthesis, but this reduction was insufficient to explain the even larger reduction observed in growth. We applied data assimilation to a simple carbon balance model to quantify the response of carbon balance as a whole in this experiment. We inferred that, in addition to photosynthesis, there are significant effects of root restriction on growth respiration, carbon allocation, and carbohydrate utilization. The second study was carried out at the EucFACE Free-Air CO2 Enrichment experiment. At this experiment, photosynthesis of the overstorey trees is increased with enriched CO2, but there is no significant effect on above-ground productivity. These mature trees have reached their maximum height but are at significant risk of canopy loss through disturbance, and we hypothesized that additional carbon taken up through photosynthesis is preferentially allocated to storage rather than growth. We tested this hypothesis by measuring stemwood non-structural carbohydrates (NSC) during a psyllid outbreak that completely defoliated the canopy in 2015. There was a significant drawdown of NSC during

Selective pressures on C4 photosynthesis evolution in grasses through the lens of optimality

OpenAIRE

Akcay, Erol; Zhou, Haoran; Helliker, Brent

2016-01-01

CO2, temperature, water availability and light intensity were potential selective pressures to propel the initial evolution and global expansion of C4 photosynthesis in grasses. To tease apart the primary selective pressures along the evolutionary trajectory, we coupled photosynthesis and hydraulics models and optimized photosynthesis over stomatal resistance and leaf/fine-root allocation. We also examined the importance of nitrogen reallocation from the dark to the light reactions. Our resul...

Moessbauer spectroscopy in studies of photosynthesis

International Nuclear Information System (INIS)

Burda, Kvetoslava

2008-01-01

Photosynthesis is a process occurring in certain species of bacteria, algae and higher plants. It transforms solar energy into various forms of energy-rich organic molecules. Photosystem II (PSII) is the 'heart' of the photosynthetic apparatus because it delivers electrons and protons for further steps of the light-driven phases of photosynthesis. There are two enigmatic iron binding structures within the core of photosynthetic apparatus, which play an important role in the electron transfer within PSII. Many investigations focus on the determination of their function which is the key to the understanding of the molecular mechanism of the energy and electron transfer within PSII. Among many methods used in this research field, the Moessbauer spectroscopy is a unique one, which gives the possibility to study changes of the valence and spin states of those two iron sites and the dynamical properties of their protein matrix in the presence of various physiological and stress conditions.

Physical stage of photosynthesis charge separation

Science.gov (United States)

Yakovlev, A. G.; Shuvalov, V. A.

2016-06-01

An analytical review is given concerning the biophysical aspects of light-driven primary charge separation in photosynthesis reaction centers (RCs) which are special pigment-protein complexes residing in a cell membrane. The primary (physical) stage of charge separation occurs in the pico- and femtosecond ranges and consists of transferring an electron along the active A-branch of pigments. The review presents vast factual material on both the general issues of primary photosynthesis and some more specific topics, including (1) the role of the inactive B-branch of pigments, (2) the effect of the protein environment on the charge separation, and (3) the participation of monomeric bacteriochlorophyll BA in primary electron acceptance. It is shown that the electron transfer and stabilization are strongly influenced by crystallographic water and tyrosine M210 molecules from the nearest environment of BA. A linkage between collective nuclear motions and electron transfer upon charge separation is demonstrated. The nature of the high quantum efficiency of primary charge separation reactions is discussed.

A quantum protective mechanism in photosynthesis

Science.gov (United States)

Marais, Adriana; Sinayskiy, Ilya; Petruccione, Francesco; van Grondelle, Rienk

2015-03-01

Since the emergence of oxygenic photosynthesis, living systems have developed protective mechanisms against reactive oxygen species. During charge separation in photosynthetic reaction centres, triplet states can react with molecular oxygen generating destructive singlet oxygen. The triplet product yield in bacteria is observed to be reduced by weak magnetic fields. Reaction centres from plants' photosystem II share many features with bacterial reaction centres, including a high-spin iron whose function has remained obscure. To explain observations that the magnetic field effect is reduced by the iron, we propose that its fast-relaxing spin plays a protective role in photosynthesis by generating an effective magnetic field. We consider a simple model of the system, derive an analytical expression for the effective magnetic field and analyse the resulting triplet yield reduction. The protective mechanism is robust for realistic parameter ranges, constituting a clear example of a quantum effect playing a macroscopic role vital for life.

What is the most prominent factor limiting photosynthesis in different layers of a greenhouse cucumber canopy?

Science.gov (United States)

Chen, Tsu-Wei; Henke, Michael; de Visser, Pieter H B; Buck-Sorlin, Gerhard; Wiechers, Dirk; Kahlen, Katrin; Stützel, Hartmut

2014-09-01

Maximizing photosynthesis at the canopy level is important for enhancing crop yield, and this requires insights into the limiting factors of photosynthesis. Using greenhouse cucumber (Cucumis sativus) as an example, this study provides a novel approach to quantify different components of photosynthetic limitations at the leaf level and to upscale these limitations to different canopy layers and the whole plant. A static virtual three-dimensional canopy structure was constructed using digitized plant data in GroIMP. Light interception of the leaves was simulated by a ray-tracer and used to compute leaf photosynthesis. Different components of photosynthetic limitations, namely stomatal (S(L)), mesophyll (M(L)), biochemical (B(L)) and light (L(L)) limitations, were calculated by a quantitative limitation analysis of photosynthesis under different light regimes. In the virtual cucumber canopy, B(L) and L(L) were the most prominent factors limiting whole-plant photosynthesis. Diffusional limitations (S(L) + M(L)) contributed Photosynthesis in the lower canopy was more limited by the biochemical capacity, and the upper canopy was more sensitive to light than other canopy parts. Although leaves in the upper canopy received more light, their photosynthesis was more light restricted than in the leaves of the lower canopy, especially when the light condition above the canopy was poor. An increase in whole-plant photosynthesis under diffuse light did not result from an improvement of light use efficiency but from an increase in light interception. Diffuse light increased the photosynthesis of leaves that were directly shaded by other leaves in the canopy by up to 55%. Based on the results, maintaining biochemical capacity of the middle-lower canopy and increasing the leaf area of the upper canopy would be promising strategies to improve canopy photosynthesis in a high-wire cucumber cropping system. Further analyses using the approach described in this study can be expected to

Development of a lab-on-chip electrochemical biosensor for water quality analysis based on microalgal photosynthesis.

Science.gov (United States)

Tsopela, A; Laborde, A; Salvagnac, L; Ventalon, V; Bedel-Pereira, E; Séguy, I; Temple-Boyer, P; Juneau, P; Izquierdo, R; Launay, J

2016-05-15

The present work was dedicated to the development of a lab-on-chip device for water toxicity analysis and more particularly herbicide detection in water. It consists in a portable system for on-site detection composed of three-electrode electrochemical microcells, integrated on a fluidic platform constructed on a glass substrate. The final goal is to yield a system that gives the possibility of conducting double, complementary detection: electrochemical and optical and therefore all materials used for the fabrication of the lab-on-chip platform were selected in order to obtain a device compatible with optical technology. The basic detection principle consisted in electrochemically monitoring disturbances in metabolic photosynthetic activities of algae induced by the presence of Diuron herbicide. Algal response, evaluated through oxygen (O2) monitoring through photosynthesis was different for each herbicide concentration in the examined sample. A concentration-dependent inhibition effect of the herbicide on photosynthesis was demonstrated. Herbicide detection was achieved through a range (blank - 1 µM Diuron herbicide solution) covering the limit of maximum acceptable concentration imposed by Canadian government (0.64 µM), using a halogen white light source for the stimulation of algal photosynthetic apparatus. Superior sensitivity results (limit of detection of around 0.1 µM) were obtained with an organic light emitting diode (OLED), having an emission spectrum adapted to algal absorption spectrum and assembled on the final system. Copyright © 2015 Elsevier B.V. All rights reserved.

Ambient UV-B radiation decreases photosynthesis in high arctic Vaccinium uliginosum

DEFF Research Database (Denmark)

Albert, Kristian Rost; Mikkelsen, Teis Nørgaard; Ro-Poulsen, H.

2008-01-01

). Leaf area, biomass, carbon, nitrogen and UV-B-absorbing compounds were determined from a late season harvest. Compared with the reduced UV-B treatment, the plants in ambient UV-B were found to have a higher content of UV-B-absorbing compounds, and canopy net photosynthesis was as an average 23% lower...... during the season. By means of the JIP-test, it was found that the potential of processing light energy through the photosynthetic machinery was slightly reduced in ambient UV-B. This indicates that not only the UV-B effects on PSII may be responsible for some of the observed reduction of photosynthesis...... on photosynthesis clearly indicates that V. uliginosum is negatively affected by the current level of UV-B....

Metabolic flux ratio analysis and cell staining suggest the existence of C4 photosynthesis in Phaeodactylum tricornutum.

Science.gov (United States)

Huang, A; Liu, L; Zhao, P; Yang, C; Wang, G C

2016-03-01

Mechanisms for carbon fixation via photosynthesis in the diatom Phaeodactylum tricornutum Bohlin were studied recently but there remains a long-standing debate concerning the occurrence of C4 photosynthesis in this species. A thorough investigation of carbon metabolism and the evidence for C4 photosynthesis based on organelle partitioning was needed. In this study, we identified the flux ratios between C3 and C4 compounds in P. tricornutum using (13)C-labelling metabolic flux ratio analysis, and stained cells with various cell-permeant fluorescent probes to investigate the likely organelle partitioning required for single-cell C4 photosynthesis. Metabolic flux ratio analysis indicated the C3/C4 exchange ratios were high. Cell staining indicated organelle partitioning required for single-cell C4 photosynthesis might exist in P. tricornutum. The results of (13)C-labelling metabolic flux ratio analysis and cell staining suggest single-cell C4 photosynthesis exists in P. tricornutum. This study provides insights into photosynthesis patterns of P. tricornutum and the evidence for C4 photosynthesis based on (13)C-labelling metabolic flux ratio analysis and organelle partitioning. © 2015 The Society for Applied Microbiology.

Estimating photosynthetic radiation use efficiency using incident light and photosynthesis of individual leaves.

Science.gov (United States)

Rosati, A; Dejong, T M

2003-06-01

It has been theorized that photosynthetic radiation use efficiency (PhRUE) over the course of a day is constant for leaves throughout a canopy if leaf nitrogen content and photosynthetic properties are adapted to local light so that canopy photosynthesis over a day is optimized. To test this hypothesis, 'daily' photosynthesis of individual leaves of Solanum melongena plants was calculated from instantaneous rates of photosynthesis integrated over the daylight hours. Instantaneous photosynthesis was estimated from the photosynthetic responses to photosynthetically active radiation (PAR) and from the incident PAR measured on individual leaves during clear and overcast days. Plants were grown with either abundant or scarce N fertilization. Both net and gross daily photosynthesis of leaves were linearly related to daily incident PAR exposure of individual leaves, which implies constant PhRUE over a day throughout the canopy. The slope of these relationships (i.e. PhRUE) increased with N fertilization. When the relationship was calculated for hourly instead of daily periods, the regressions were curvilinear, implying that PhRUE changed with time of the day and incident radiation. Thus, linearity (i.e. constant PhRUE) was achieved only when data were integrated over the entire day. Using average PAR in place of instantaneous incident PAR increased the slope of the relationship between daily photosynthesis and incident PAR of individual leaves, and the regression became curvilinear. The slope of the relationship between daily gross photosynthesis and incident PAR of individual leaves increased for an overcast compared with a clear day, but the slope remained constant for net photosynthesis. This suggests that net PhRUE of all leaves (and thus of the whole canopy) may be constant when integrated over a day, not only when the incident PAR changes with depth in the canopy, but also when it varies on the same leaf owing to changes in daily incident PAR above the canopy. The

Programs of Study as a State Policy Mandate: A Longitudinal Study of the South Carolina Personal Pathways to Success Initiative. Final Technical Report: Major Findings and Implications

Science.gov (United States)

Hammond, Cathy; Drew, Sam F.; Withington, Cairen; Griffith, Cathy; Swiger, Caroline M.; Mobley, Catherine; Sharp, Julia L.; Stringfield, Samuel C.; Stipanovic, Natalie; Daugherty, Lindsay

2013-01-01

This is the final technical report from the National Research Center for Career and Technical Education's (NRCCTE's) five-year longitudinal study of South Carolina's Personal Pathway to Success initiative, which was authorized by the state's Education and Economic Development Act (EEDA) in 2005. NRCCTE-affiliated researchers at the National…

Photosynthesis: an interactive didactic model’s use to the learning and teaching process

Directory of Open Access Journals (Sweden)

Vanessa Liesenfeld

2015-06-01

Full Text Available Photosynthesis is a complex process that involves the implementation of several reactions which, many times, makes this content difficult for students to understand. The objective of this study was to investigate if an interactive didactic model, crafted with simple materials, could facilitate the understanding and learning of students on photosynthesis. Initially students of first year high school class from a public school Western of Paraná were asked to diagram what they knew about photosynthesis and respond to a questionnaire. It was concluded that many of the students’ prior concepts were general or inaccurate, such as the idea of photosynthesis being the process of respiration in plants, and O2 coming from the CO2, not from the photo-oxidation of water. These prior conceptions were important for planning the approach to the subject. The process of photosynthesis was then covered in lecture and dialogued, using the interactive didactic model to highlight the explanations. A new questionnaire was completed by the students, and concluded that the use of the interactive didactic model was efficient, since it helped to consolidate correct concepts and simultaneously, introduced new ones as well it shook the equivocal relations.

Exploring undergraduates' understanding of photosynthesis using diagnostic question clusters.

Science.gov (United States)

Parker, Joyce M; Anderson, Charles W; Heidemann, Merle; Merrill, John; Merritt, Brett; Richmond, Gail; Urban-Lurain, Mark

2012-01-01

We present a diagnostic question cluster (DQC) that assesses undergraduates' thinking about photosynthesis. This assessment tool is not designed to identify individual misconceptions. Rather, it is focused on students' abilities to apply basic concepts about photosynthesis by reasoning with a coordinated set of practices based on a few scientific principles: conservation of matter, conservation of energy, and the hierarchical nature of biological systems. Data on students' responses to the cluster items and uses of some of the questions in multiple-choice, multiple-true/false, and essay formats are compared. A cross-over study indicates that the multiple-true/false format shows promise as a machine-gradable format that identifies students who have a mixture of accurate and inaccurate ideas. In addition, interviews with students about their choices on three multiple-choice questions reveal the fragility of students' understanding. Collectively, the data show that many undergraduates lack both a basic understanding of the role of photosynthesis in plant metabolism and the ability to reason with scientific principles when learning new content. Implications for instruction are discussed.

Final Technical Report - Kotzebue Wind Power Project - Volume II

Energy Technology Data Exchange (ETDEWEB)

Rana Zucchi, Global Energy Concepts, LLC; Brad Reeve, Kotzebue Electric Association; DOE Project Officer - Doug Hooker

2007-10-31

The Kotzebue Wind Power Project is a joint undertaking of the U.S. Department of Energy (DOE); Kotzebue Electric Association (KEA); and the Alaska Energy Authority (AEA). The goal of the project is to develop, construct, and operate a wind power plant interconnected to a small isolated utility grid in an arctic climate in Northwest Alaska. The primary objective of KEA’s wind energy program is to bring more affordable electricity and jobs to remote Alaskan communities. DOE funding has allowed KEA to develop a multi-faceted approach to meet these objectives that includes wind project planning and development, technology transfer, and community outreach. The first wind turbines were installed in the summer of 1997 and the newest turbines were installed in the spring of 2007. The total installed capacity of the KEA wind power project is 1.16 MW with a total of 17 turbines rated between 65 kW and 100 kW. The operation of the wind power plant has resulted in a wind penetration on the utility system in excess of 35% during periods of low loads. This document and referenced attachments are presented as the final technical report for the U.S. Department of Energy (DOE) grant agreement DE-FG36-97GO10199. Interim deliverables previously submitted are also referenced within this document and where reasonable to do so, specific sections are incorporated in the report or attached as appendices.

Energy-related inventions program invention 637. Final technical report

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-07-31

The final technical report for the Pegasus plow, a stalk and root embedding apparatus, describes progress from the development stage to the product support stage. The US Department of Agriculture - Agriculture Research Service (ARS) is now in the second year of a three year study comparing the Pegasus to conventional tillage. So far, no downside has been with the Pegasus and the following benefits have been documented: (1) Energy savings of 65.0 kilowatt hours per hectare over conventional tillage. This is when the Pegasus plow is used to bury whole stalks, and represents a 70% savings over conventional tillage (92.5 kilowatt hours per hectare). (2) Four to seven fewer passes of tillage, depending on the particular situation. This represents a substantial time savings to farmers. (3) So far, no differences in cotton yields. Recent cotton boll counts in one study indicate a higher yield potential with the Pegasus. (4) No disease problems. (5) Significantly higher levels of organic matter in the soil. A hypothesis of the study is that whole stalk burial may reduce plant disease problems. This hypothesis has not yet been proven. (6) Significantly higher levels of nitrate nitrogen. Total nitrogen and ammonia nitrogen trended higher but were not significantly different. This shows that whole stalk burial does not adversely affect the nitrogen cycle in the soil and may actually improve it. The marketing support stage of the project is also described in the report.

Exogenous 5-Aminolevulenic Acid Promotes Antioxidative Defence System, Photosynthesis and Growth in Soybean against Cold Stress

Directory of Open Access Journals (Sweden)

Elahe MANAFI

2015-12-01

Full Text Available In the present study, the possibility of enhancing cold stress tolerance of young soybean plants (Glycine max [L.] Merr by exogenous application of 5-aminolevulinic acid (ALA was investigated. ALA was applied at various concentrations (0, 0.3, 0.6 and 0.9 mM by seed priming and foliar application method. After ALA treatment, the plants were subjected to cold stress at 10 ± 0.5 °C for 72 h. Cold stress significantly decreased plant growth, relative water content, chlorophyll, photosynthesis and stomatal conductivity, while it increased electrolyte leakage and proline accumulation. ALA at low concentrations (0.3 mM protected plants against cold stress, enhancing plant height, shoot fresh and dry weight, chlorophyll content, photosynthesis, stomatal conductivity as well as relative water content. Increase of electrolyte leakage was also prevented by 0.6 mM ALA. ALA also enhanced superoxide dismutase and catalase activities at 0.6 mM concentration especially under cold stress conditions. Proline increased with increasing in ALA concentration under both temperature conditions. In most cases, application of ALA by spraying method was better than seed priming method. Results showed that ALA, which is considered as an endogenous plant growth regulator, can be used effectively to protect soybean plants from the damaging effects of cold stress, by enhancing the activity of antioxidative enzymes, protecting cell membrane against reactive oxygen species and finally by promoting chlorophyll synthesis, leading to more intense photosynthesis and more carbon fixation, without any adverse effect on the plant growth.

How carotenoids protect bacterial photosynthesis.

OpenAIRE

Cogdell, R J; Howard, T D; Bittl, R; Schlodder, E; Geisenheimer, I; Lubitz, W

2000-01-01

The essential function of carotenoids in photosynthesis is to act as photoprotective agents, preventing chlorophylls and bacteriochlorophylls from sensitizing harmful photodestructive reactions in the presence of oxygen. Based upon recent structural studies on reaction centres and antenna complexes from purple photosynthetic bacteria, the detailed organization of the carotenoids is described. Then with specific reference to bacterial antenna complexes the details of the photoprotective role, ...

Carrying photosynthesis genes increases ecological fitness of cyanophage in silico.

Science.gov (United States)

Hellweger, Ferdi L

2009-06-01

Several viruses infecting marine cyanobacteria carry photosynthesis genes (e.g. psbA, hli) that are expressed, yield proteins (D1, HLIP) and help maintain the cell's photosynthesis apparatus during the latent period. This increases energy and speeds up virus production, allowing for a reduced latent period (a fitness benefit), but it also increases the DNA size, which slows down new virus production and reduces burst size (a fitness cost). How do these genes affect the net ecological fitness of the virus? Here, this question is explored using a combined systems biology and systems ecology ('systems bioecology') approach. A novel agent-based model simulates individual cyanobacteria cells and virus particles, each with their own genes, transcripts, proteins and other properties. The effect of D1 and HLIP proteins is explicitly considered using a mechanistic photosynthesis component. The model is calibrated to the available database for Prochlorococcus ecotype MED4 and podovirus P-SSP7. Laboratory- and field-scale in silico survival, competition and evolution (gene packaging error) experiments with wild type and genetically engineered viruses are performed to develop vertical survival and fitness profiles, and to determine the optimal gene content. The results suggest that photosynthesis genes are nonessential, increase fitness in a manner correlated with irradiance, and that the wild type has an optimal gene content.

Measurement of Solar Spectra Relating to Photosynthesis and Solar Cells: An Inquiry Lab for Secondary Science

Science.gov (United States)

Ruggirello, Rachel M.; Balcerzak, Phyllis; May, Victoria L.; Blankenship, Robert E.

2012-01-01

The process of photosynthesis is central to science curriculum at all levels. This article describes an inquiry-based laboratory investigation developed to explore the impact of light quality on photosynthesis and to connect this process to current research on harvesting solar energy, including bioenergy, artificial photosynthesis, and solar…

Technical considerations associated with spent fuel acceptance. Final report

International Nuclear Information System (INIS)

Supko, E.M.

1996-06-01

This study was initiated by the Electric Power Research Institute (EPRI) to identify technical considerations associated with spent fuel acceptance and implementation of a waste management system that includes the use of transportable storage systems, and to serve as an opening dialogue among Standard Contract Holders and the department of Energy's Office of Civilian Radioactive Waste management (OCRWM) prior to the development of waste acceptance criteria or issuance of a Notice of Proposed Rulemaking by OCRWM to amend the Standard Contract. The original purpose of the Notice of Proposed Rulemaking was to address changes to the Standard Contract to implement a multi-purpose canister based system and to address other issues that were not adequately addressed in the standard contract. Even if DOE does not develop a multi-purpose canister based system for waste acceptance, it will still be necessary to develop waste acceptance criteria in order to accept spent fuel in transportable storage systems that are being deployed for at-reactor storage. In this study, technical issues associated with spent fuel acceptance will be defined and potential options and alternatives for resolution of technical considerations will be explored

Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Held, Isaac [Princeton Univ., NJ (United States); Balaji, V. [Princeton Univ., NJ (United States); Fueglistaler, Stephan [Princeton Univ., NJ (United States)

2016-09-19

We have constructed and analyzed a series of idealized models of tropical convection interacting with large-scale circulations, with 25-50km resolution and with 1-2km cloud resolving resolution to set the stage for rigorous tests of convection closure schemes in high resolution global climate models. Much of the focus has been on the climatology of tropical cyclogenesis in rotating systems and the related problem of the spontaneous aggregation of convection in non-rotating systems. The PI (Held) will be delivering the honorary Bjerknes lecture at the Fall 2016 AGU meeting in December on this work. We have also provided new analyses of long-standing issues related to the interaction between convection and the large-scale circulation: Kelvin waves in the upper troposphere and lower stratosphere, water vapor transport into the stratosphere, and upper tropospheric temperature trends. The results of these analyses help to improve our understanding of processes, and provide tests for future high resolution global modeling. Our final goal of testing new convections schemes in next-generation global atmospheric models at GFDL has been left for future work due to the complexity of the idealized model results meant as tests for these models uncovered in this work and to computational resource limitations. 11 papers have been published with support from this grant, 2 are in review, and another major summary paper is in preparation.

Ecosystem respiration depends strongly on photosynthesis in a temperate heath

DEFF Research Database (Denmark)

Larsen, Klaus Steenberg; Ibrom, Andreas; Beier, Claus

2007-01-01

We measured net ecosystem CO2 flux (F-n) and ecosystem respiration (R-E), and estimated gross ecosystem photosynthesis (P-g) by difference, for two years in a temperate heath ecosystem using a chamber method. The exchange rates of carbon were high and of similar magnitude as for productive forest...... ecosystems with a net ecosystem carbon gain during the second year of 293 +/- 11 g C m(-2) year(-1) showing that the carbon sink strength of heather-dominated ecosystems may be considerable when C. vulgaris is in the building phase of its life cycle. The estimated gross ecosystem photosynthesis and ecosystem.......65) was improved when the P-g rate was incorporated into the model (second year; R-2 = 0.79), suggesting that daytime R-E increased with increasing photosynthesis. Furthermore, the temperature sensitivity of R-E decreased from apparent Q(10) values of 3.3 to 3.9 by the classic equation to a more realistic Q(10...

Electromagnetic Radiation Disturbed the Photosynthesis of Microcystis aeruginosa at the Proteomics Level.

Science.gov (United States)

Tang, Chao; Yang, Chuanjun; Yu, Hui; Tian, Shen; Huang, Xiaomei; Wang, Weiyi; Cai, Peng

2018-01-11

Photosynthesis of Microcystis aeruginosa under Electromagnetic Radiation (1.8 GHz, 40 V/m) was studied by using the proteomics. A total of 30 differentially expressed proteins, including 15 up-regulated and 15 down-regulated proteins, were obtained in this study. The differentially expressed proteins were significantly enriched in the photosynthesis pathway, in which the protein expression levels of photosystems II cytochrome b559 α subunit, cytochrome C550, PsbY, and F-type ATP synthase (a, b) decreased. Our results indicated that electromagnetic radiation altered the photosynthesis-related protein expression levels, and aimed at the function of photosynthetic pigments, photosystems II potential activity, photosynthetic electron transport process, and photosynthetic phosphorylation process of M. aeruginosa. Based on the above evidence, that photoreaction system may be deduced as a target of electromagnetic radiation on the photosynthesis in cyanobacteria; the photoreaction system of cyanobacteria is a hypothetical "shared target effector" that responds to light and electromagnetic radiation; moreover, electromagnetic radiation does not act on the functional proteins themselves but their expression processes.

O2-insensitive photosynthesis in C3 plants: its occurrence and a possible explanation

International Nuclear Information System (INIS)

Sharkey, T.D.

1985-01-01

Leaves of C 3 plants which exhibit a normal O 2 inhibition of CO 2 fixation at less than saturating light intensity were found to exhibit O 2 -insensitive photosynthesis at high light. This behavior was observed in Phaseolus vulgaris L., Xanthium strumarium L., and Scrophularia desertorum (Shaw.) Munz. O 2 -insensitive photosynthesis has been reported in nine other C 3 species and usually occurred when the intercellular CO 2 pressure was about double the normal pressure. A lack of O 2 inhibition of photosynthesis was always accompanied by a failure of increased CO 2 pressure to stimulate photosynthesis to the expected degree. O 2 -insensitive photosynthesis also occurred after plants had been water stressed. Under such conditions, however, photosynthesis became O 2 and CO 2 insensitive at physiological CO 2 pressures. Postillumination CO 2 exchange kinetics showed that O 2 and CO 2 insensitivity was not the result of elimination of photorespiration. It is proposed that O 2 and CO 2 insensitivity occurs when the concentration of phosphate in the chloroplast stroma cannot be both high enough to allow photophosphorylation and low enough to allow starch and sucrose synthesis at the rates required by the rest of the photosynthetic component processes. Under these conditions, the energy diverted to photorespiration does not adversely affect the potential for CO 2 assimilation

Effects of space environment on chlorophyll fluorescence and photosynthesis characteristics of wheat

International Nuclear Information System (INIS)

Lu Li; Lv Jinyin; Gong Qingzhu; Gao Junfeng

2006-01-01

The effects of the space environment on the chlorophyll fluorescence parameters and photosynthesis characteristics of wheat cultivars, Xinong 1043 M1 and Shaan253 M 1 , were studied. The results showed that the decrement of contents of PS II primary photochemical efficiency (F v /F m ), potential activity (F v /F 0 ), photochemical quenching coefficient (qP) and photosynthesis rate (Pn) were less than that of control, increment of non-photochemical quenching coefficient (qN) were more than that of control. The results suggested that photosynthetic apparatus were damaged, photosynthetic electron transport, photosynthetic primary reaction were inhibited, rate of photosynthesis decreased and growth of M 1 plant were retarded, which leading to thousand kernel weights decreased. (authors)

The importance of micrometeorological variations for photosynthesis and transpiration in a boreal coniferous forest

DEFF Research Database (Denmark)

Schurgers, Guy; Lagergren, F.; Molder, M.

2015-01-01

the importance of vertical variations in light, temperature, CO2 concentration and humidity within the canopy for fluxes of photosynthesis and transpiration of a boreal coniferous forest in central Sweden. A leaf-level photosynthesis-stomatal conductance model was used for aggregating these processes to canopy...... abovecanopy and within-canopy humidity, and despite large gradients in CO2 concentration during early morning hours after nights with stable conditions, neither humidity nor CO2 played an important role for vertical heterogeneity of photosynthesis and transpiration....

Modeling photosynthesis of Spartina alterniflora (smooth cordgrass) impacted by the Deepwater Horizon oil spill using Bayesian inference

International Nuclear Information System (INIS)

Wu Wei; Biber, Patrick D; Peterson, Mark S; Gong Chongfeng

2012-01-01

To study the impact of the Deepwater Horizon oil spill on photosynthesis of coastal salt marsh plants in Mississippi, we developed a hierarchical Bayesian (HB) model based on field measurements collected from July 2010 to November 2011. We sampled three locations in Davis Bayou, Mississippi (30.375°N, 88.790°W) representative of a range of oil spill impacts. Measured photosynthesis was negative (respiration only) at the heavily oiled location in July 2010 only, and rates started to increase by August 2010. Photosynthesis at the medium oiling location was lower than at the control location in July 2010 and it continued to decrease in September 2010. During winter 2010–2011, the contrast between the control and the two impacted locations was not as obvious as in the growing season of 2010. Photosynthesis increased through spring 2011 at the three locations and decreased starting with October at the control location and a month earlier (September) at the impacted locations. Using the field data, we developed an HB model. The model simulations agreed well with the measured photosynthesis, capturing most of the variability of the measured data. On the basis of the posteriors of the parameters, we found that air temperature and photosynthetic active radiation positively influenced photosynthesis whereas the leaf stress level negatively affected photosynthesis. The photosynthesis rates at the heavily impacted location had recovered to the status of the control location about 140 days after the initial impact, while the impact at the medium impact location was never severe enough to make photosynthesis significantly lower than that at the control location over the study period. The uncertainty in modeling photosynthesis rates mainly came from the individual and micro-site scales, and to a lesser extent from the leaf scale. (letter)

Recruitment of pre-existing networks during the evolution of C4 photosynthesis.

Science.gov (United States)

Reyna-Llorens, Ivan; Hibberd, Julian M

2017-09-26

During C 4 photosynthesis, CO 2 is concentrated around the enzyme RuBisCO. The net effect is to reduce photorespiration while increasing water and nitrogen use efficiencies. Species that use C 4 photosynthesis have evolved independently from their C 3 ancestors on more than 60 occasions. Along with mimicry and the camera-like eye, the C 4 pathway therefore represents a remarkable example of the repeated evolution of a highly complex trait. In this review, we provide evidence that the polyphyletic evolution of C 4 photosynthesis is built upon pre-existing metabolic and genetic networks. For example, cells around veins of C 3 species show similarities to those of the C 4 bundle sheath in terms of C 4 acid decarboxylase activity and also the photosynthetic electron transport chain. Enzymes of C 4 photosynthesis function together in gluconeogenesis during early seedling growth of C 3 Arabidopsis thaliana Furthermore, multiple C 4 genes appear to be under control of both light and chloroplast signals in the ancestral C 3 state. We, therefore, hypothesize that relatively minor rewiring of pre-existing genetic and metabolic networks has facilitated the recurrent evolution of this trait. Understanding how these changes are likely to have occurred could inform attempts to install C 4 traits into C 3 crops.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'. © 2017 The Author(s).

Surviving metabolic arrest: photosynthesis during desiccation and rehydration in resurrection plants.

Science.gov (United States)

Challabathula, Dinakar; Puthur, Jos T; Bartels, Dorothea

2016-02-01

Photosynthesis is the key process that is affected by dehydration in plants. Desiccation-tolerant resurrection plants can survive conditions of very low relative water content. During desiccation, photosynthesis is not operational, but is recovered within a short period after rehydration. While homoiochlorophyllous resurrection plants retain their photosynthetic apparatus during desiccation, poikilochlorophyllous resurrection species dismantle chloroplasts and degrade chlorophyll but resynthesize them again during rehydration. Dismantling the chloroplasts avoids the photooxidative stress in poikilochlorophyllous resurrection plants, whereas it is minimized in homoiochlorophyllous plants through the synthesis of antioxidant enzymes and protective proteins or metabolites. Although the cellular protection mechanisms in both of these species vary, these mechanisms protect cells from desiccation-induced damage and restore photosynthesis upon rehydration. Several of the proteins synthesized during dehydration are localized in chloroplasts and are believed to play major roles in the protection of photosynthetic structures and in recovery in resurrection species. This review focuses on the strategies of resurrection plants in terms of how they protect their photosynthetic apparatus from oxidative stress during desiccation without membrane damage and with full recovery during rehydration. We review the role of the dehydration-induced protection mechanisms in chloroplasts and how photosynthesis is restored during rehydration. © 2015 New York Academy of Sciences.

Rising CO2 widens the transpiration-photosynthesis optimality space

Science.gov (United States)

de Boer, Hugo J.; Eppinga, Maarten B.; Dekker, Stefan C.

2016-04-01

Stomatal conductance (gs) and photosynthetic biochemistry, typically expressed by the temperature-adjusted maximum rates of carboxylation (V cmax) and electron transport (Jmax), are key traits in land ecosystem models. Contrary to the many approaches available for simulating gs responses, the biochemical parameters V cmax and Jmax are often treated as static traits in ecosystem models. However, observational evidence indicates that V cmax and Jmax respond to persistent changes in atmospheric CO2. Hence, ecosystem models may be improved by incorporating coordinated responses of photosynthetic biochemistry and gs to atmospheric CO2. Recently, Prentice et al. (2014) proposed an optimality framework (referred to as the Prentice framework from here on) to predict relationships between V cmax and gs based on Fick's law, Rubisco-limited photosynthesis and the carbon costs of transpiration and photosynthesis. Here we show that this framework is, in principle, suited to predict CO2-induced changes in the V cmax -gs relationships. The framework predicts an increase in the V cmax:gs-ratio with higher atmospheric CO2, whereby the slope of this relationship is determined by the carbon costs of transpiration and photosynthesis. For our empirical analyses we consider that the carbon cost of transpiration is positively related to the plant's Huber value (sapwood area/leaf area), while the carbon cost of photosynthesis is positively related to the maintenance cost of the photosynthetic proteins. We empirically tested the predicted effect of CO2 on the V cmax:gs-ratio in two genotypes of Solanum dulcamara (bittersweet) that were grown from seeds to maturity under 200, 400 and 800 ppm CO2 in walk-in growth chambers with tight control on light, temperature and humidity. Seeds of the two Solanum genotypes were obtained from two distinct natural populations; one adapted to well-drained sandy soil (the 'dry' genotype) and one adapted to poorly-drained clayey soil (the 'wet' genotype

Carbon dioxide fixation by artificial photosynthesis

Energy Technology Data Exchange (ETDEWEB)

Ibusuki, Takashi; Koike, Kazuhide; Ishitani, Osamu [National Inst. for Resources and Environment, AIST, MITI, Tsukuba, Ibaraki (Japan)

1993-12-31

Green plants can absorb atmospheric CO{sub 2} and transform it to sugars, carbohydrates through their photosynthetic systems, but they become the source of CO{sub 2} when they are dead. This is the reason why artificial leaves which can be alive forever should be developed to meet with global warming due to the increase of CO{sub 2} concentration. The goal of artificial photosynthesis is not to construct the same system as the photosynthetic one, but to mimic the ability of green plants to utilize solar energy to make high energy chemicals. Needless to say, the artificial photosynthetic system is desired to be as simple as possible and to be as efficient as possible. From the knowledge on photosynthesis and the results of previous investigations, the critical components of artificial photosynthetic system are understood as follows: (1) light harvesting chromophore, (2) a center for electron transfer and charge separation, (3) catalytic sites for converting small molecules like water and CO{sub 2} (mutilelectron reactions) which are schematically described.

Box photosynthesis modeling results for WRF/CMAQ LSM

Data.gov (United States)

U.S. Environmental Protection Agency — Box Photosynthesis model simulations for latent heat and ozone at 6 different FLUXNET sites. This dataset is associated with the following publication: Ran, L., J....

Evolution of the Z-scheme of photosynthesis: a perspective.

Science.gov (United States)

Govindjee; Shevela, Dmitriy; Björn, Lars Olof

2017-09-01

The concept of the Z-scheme of oxygenic photosynthesis is in all the textbooks. However, its evolution is not. We focus here mainly on some of the history of its biophysical aspects. We have arbitrarily divided here the 1941-2016 period into three sub-periods: (a) Origin of the concept of two light reactions: first hinted at, in 1941, by James Franck and Karl Herzfeld; described and explained, in 1945, by Eugene Rabinowitch; and a clear hypothesis, given in 1956 by Rabinowitch, of the then available cytochrome experiments: one light oxidizing it and another reducing it; (b) Experimental discovery of the two light reactions and two pigment systems and the Z-scheme of photosynthesis: Robert Emerson's discovery, in 1957, of enhancement in photosynthesis when two light beams (one in the far-red region, and the other of shorter wavelengths) are given together than when given separately; and the 1960 scheme of Robin Hill & Fay Bendall; and (c) Evolution of the many versions of the Z-Scheme: Louis Duysens and Jan Amesz's 1961 experiments on oxidation and reduction of cytochrome f by two different wavelengths of light, followed by the work of many others for more than 50 years.

Operation of trans-thylakoid thiol-metabolizing pathways in photosynthesis

Directory of Open Access Journals (Sweden)

Mohamed eKaramoko

2013-11-01

Full Text Available Thiol oxidation to disulfides and the reverse reaction, i.e. disulfide reduction to free thiols, are under the control of catalysts in vivo. Enzymatically assisted thiol-disulfide chemistry is required for the biogenesis of all energy-transducing membrane systems. However, until recently, this had only been demonstrated for the bacterial plasma membrane. Long considered to be vacant, the thylakoid lumen has now moved to the forefront of photosynthesis research with the realization that its proteome is far more complicated than initially anticipated. Several lumenal proteins are known to be disulfide bonded in Arabidopsis, highlighting the importance of sulfhydryl oxidation in the thylakoid lumen. While disulfide reduction in the plastid stroma is known to activate several enzymatic activities, it appears that it is the reverse reaction, i.e. thiol oxidation that is required for the activity of several lumen-resident proteins. This paradigm for redox regulation in the thylakoid lumen has opened a new frontier for research in the field of photosynthesis. Of particular significance in this context is the discovery of trans-thylakoid redox pathways controlling disulfide bond formation and reduction, which are required for photosynthesis.

Effects of SO/sub 2/ on photosynthesis and nitrogen fixation

Energy Technology Data Exchange (ETDEWEB)

Haellgren, J E; Huss, K

1975-06-15

Responses of photosynthesis and nitrogen fixation to NaHSO/sub 3/ (10/sup -5/ to 5 x 10/sup -3/ M) were investigated in the lichen Stereocaulon paschale (L.) Fr. and the blue-green alga Anabaena cylindrica Lemmermann. The treatments were performed in buffered media with varying pH (5.8 to 8.1) and light conditions (0 to 32 W x m/sup -2/). The activities of the intact organisms were investigated, under the same environmental conditions, with /sup 14/C liquid scintillation and acetylene reduction techniques respectively. The nitrogen fixation proved to be more susceptible than photosynthesis, in both organisms, and in all cases treatments at pH 5.8 were more inhibitory than at higher pH-values. Treatment with 5 x 10/sup -4/ M NaHSO/sub 3/ at pH 5.8 caused no reduction of photosynthesis in S. paschale, while the inhibition of nitrogen fixation was 97%. For A. cylindrica the corresponding values were 40% and 75% respectively. Short-time treatments of A. cylindrica showed that the nitrogen fixation was more rapidly affected than photosynthesis. The inhibition of nitrogenase activity and CO/sub 2/-fixation was smaller in the dark and increased at higher light intensities. Both processes showed a good capacity for recovery after removal of the NaHSO/sub 3/ solution. Also the clumping ability of A. cylindrica was disturbed by NaHSO/sub 3/ treatments.

Photochemistry and enzymology of photosynthesis

Energy Technology Data Exchange (ETDEWEB)

Radmer, R.

1979-07-30

In the first task, a specially designed mass spectrometer system monitors the gas exchange occurring in response to single short flashes of light. This apparatus will be primarily used to study photosystem II donor reactions, such as the photooxidation of hydroxylamine, hydrazine, and hydrogen peroxide. This technique will also be used to study the light-induced exchange of O/sub 2/ and CO/sub 2/ in algae. The second task, biochemical studies, will focus on the role of chloroplast copper in photosynthesis. We propose to isolate, purify, and characterize the chloroplast copper enzyme polyphenol oxidase, and attempt to elucidate its role in photosynthesis. These studies will be integrated with a new program devoted to the biochemical response of the photosynthetic membrane to stress. The third task is a series of studies on the light-harvesting and electron-transport mechanisms of C/sub 4/ plants. This program will address three basic problems: (1) the effect of different preparative procedures on various photosynthetic reactions, with particular emphasis on photosystem II reactions in corn bundle sheath chloroplasts; (2) the development and testing of photosystem II assays; and (3) studies of the stoichiometry of electron carriers in bundle sheath chloroplasts, and whether cyclic phosphorylation could be a major pathway in this tissue.

Final technical report; Mercury Release from Organic matter (OM) and OM-Coated Mineral Surfaces

Energy Technology Data Exchange (ETDEWEB)

Aiken, George

2014-10-02

This document is the final technical report for a project designed to address fundamental processes controlling the release of mercury from flood plain soils associated with East Fork Poplar Creek, Tennessee near the U.S. Department of Energy Oak Ridge facility. The report summarizes the activities, findings, presentations, and publications resulting from an award to the U.S. Geological that were part of a larger overall effort including Kathy Nagy (University of Illinois, Chicago, Ill) and Joseph Ryan (University of Colorado, Boulder, CO). The specific charge for the U.S.G.S. portion of the study was to provide analytical support for the larger group effort (Nagy and Ryan), especially with regard to analyses of Hg and dissolved organic matter, and to provide information about the release of mercury from the floodplain soils.

The Path of Carbon in Photosynthesis VII. Respiration and Photosynthesis

Science.gov (United States)

Benson, A. A.; Calvin, M.

1949-07-21

The relationship of respiration to photosynthesis in barley seedling leaves and the algae, Chlorella and Scenedesmus, has been investigated using radioactive carbon dioxide and the techniques of paper chromatography and radioautography. The plants are allowed to photosynthesize normally for thirty seconds in c{sup 14}O{sub 2} after which they are allowed to respire in air or helium in the light or dark. Respiration of photosynthetic intermediates as evidenced by the appearance of labeled glutomic, isocitric, fumaric and succinic acids is slower in the light than in the dark. Labeled glycolic acid is observed in barley and algae. It disappears rapidly in the dark and is maintained and increased in quantity in the light in C0{sub 2}-free air.

A natural variant of NAL1, selected in high-yield rice breeding programs, pleiotropically increases photosynthesis rate

Science.gov (United States)

Takai, Toshiyuki; Adachi, Shunsuke; Taguchi-Shiobara, Fumio; Sanoh-Arai, Yumiko; Iwasawa, Norio; Yoshinaga, Satoshi; Hirose, Sakiko; Taniguchi, Yojiro; Yamanouchi, Utako; Wu, Jianzhong; Matsumoto, Takashi; Sugimoto, Kazuhiko; Kondo, Katsuhiko; Ikka, Takashi; Ando, Tsuyu; Kono, Izumi; Ito, Sachie; Shomura, Ayahiko; Ookawa, Taiichiro; Hirasawa, Tadashi; Yano, Masahiro; Kondo, Motohiko; Yamamoto, Toshio

2013-01-01

Improvement of leaf photosynthesis is an important strategy for greater crop productivity. Here we show that the quantitative trait locus GPS (GREEN FOR PHOTOSYNTHESIS) in rice (Oryza sativa L.) controls photosynthesis rate by regulating carboxylation efficiency. Map-based cloning revealed that GPS is identical to NAL1 (NARROW LEAF1), a gene previously reported to control lateral leaf growth. The high-photosynthesis allele of GPS was found to be a partial loss-of-function allele of NAL1. This allele increased mesophyll cell number between vascular bundles, which led to thickened leaves, and it pleiotropically enhanced photosynthesis rate without the detrimental side effects observed in previously identified nal1 mutants, such as dwarf plant stature. Furthermore, pedigree analysis suggested that rice breeders have repeatedly selected the high-photosynthesis allele in high-yield breeding programs. The identification and utilization of NAL1 (GPS) can enhance future high-yield breeding and provides a new strategy for increasing rice productivity. PMID:23985993

THE GENESIS OF PHOTOSYNTHESIS TYPES AS THE BASIS OF ECOLOGICAL EXPANSION OF HALOPHYTIC PLANTS

Directory of Open Access Journals (Sweden)

Pyurko O.Ye.

2011-12-01

Full Text Available The C3, C4, and CAM photosynthesis types are considerably differed by CO2 absorption intensity, its biochemistry, saturation level, water productivity, biological productivity, and other different features, which secure the plants survival at stress and extreme conditions. The aim of current research was to discover the photosynthesis peculiarities at halophytic plants species (Salicornia europaea L., Halimione pedunculata, Artemisia santonica L., Plantago lanceolata L. by salinity at model and natural conditions, and to generalize data in historical aspect. It was constituted that S. europaea L. was characterized by C3 photosynthesis passage which was switched on CAM CO2 fixation under soil salinity conditions till 4-4,5 %, but glycophyte A.santonica was immanent C4assimilation way of aspartate type.Analysis of literature data and own research allows to find out that in majority the C3photosynthesis dependence from environmental factors described by determinate curve with matched mathematical expression. It was suggested to generalize the data by Lagrange polynomial. The obtained results proved that the pattern of photosynthesis evolution is: C3 → C4 → CAM with commute possibilities: C3 → CAM; C4 → CAM.

Water relations and photosynthesis along an elevation gradient for Artemisia tridentata during an historic drought.

Science.gov (United States)

Reed, Charlotte C; Loik, Michael E

2016-05-01

Quantifying the variation in plant-water relations and photosynthesis over environmental gradients and during unique events can provide a better understanding of vegetation patterns in a future climate. We evaluated the hypotheses that photosynthesis and plant water potential would correspond to gradients in precipitation and soil moisture during a lengthy drought, and that experimental water additions would increase photosynthesis for the widespread evergreen shrub Artemisia tridentata ssp. vaseyana. We quantified abiotic conditions and physiological characteristics for control and watered plants at 2135, 2315, and 2835 m near Mammoth Lakes, CA, USA, at the ecotone of the Sierra Nevada and Great Basin ecoregions. Snowfall, total precipitation, and soil moisture increased with elevation, but air temperature and soil N content did not. Plant water potential (Ψ), stomatal conductance (g s), maximum photosynthetic rate (A max), carboxylation rate (V cmax), and electron transport rate (J max) all significantly increased with elevations. Addition of water increased Ψ, g s, J max, and A max only at the lowest elevation; g s contributed about 30 % of the constraints on photosynthesis at the lowest elevation and 23 % at the other two elevations. The physiology of this foundational shrub species was quite resilient to this 1-in-1200 year drought. However, plant water potential and photosynthesis corresponded to differences in soil moisture across the gradient. Soil re-wetting in early summer increased water potential and photosynthesis at the lowest elevation. Effects on water relations and photosynthesis of this widespread, cold desert shrub species may be disproportionate at lower elevations as drought length increases in a future climate.

Dorsoventral variations in dark chilling effects on photosynthesis and stomatal function in Paspalum dilatatum leaves.

Science.gov (United States)

Soares-Cordeiro, Ana Sofia; Driscoll, Simon P; Arrabaça, Maria Celeste; Foyer, Christine H

2011-01-01

The effects of dark chilling on the leaf-side-specific regulation of photosynthesis were characterized in the C(4) grass Paspalum dilatatum. CO(2)- and light-response curves for photosynthesis and associated parameters were measured on whole leaves and on each leaf side independently under adaxial and abaxial illumination before and after plants were exposed to dark chilling for one or two consecutive nights. The stomata closed on the adaxial sides of the leaves under abaxial illumination and no CO(2) uptake could be detected on this surface. However, high rates of whole leaf photosynthesis were still observed because CO(2) assimilation rates were increased on the abaxial sides of the leaves under abaxial illumination. Under adaxial illumination both leaf surfaces contributed to the inhibition of whole leaf photosynthesis observed after one night of chilling. After two nights of chilling photosynthesis remained inhibited on the abaxial side of the leaf but the adaxial side had recovered, an effect related to increased maximal ribulose-1,5-bisphosphate carboxylation rates (V(cmax)) and enhanced maximal electron transport rates (J(max)). Under abaxial illumination, whole leaf photosynthesis was decreased only after the second night of chilling. The chilling-dependent inhibition of photosynthesis was located largely on the abaxial side of the leaf and was related to decreased V(cmax) and J(max), but not to the maximal phosphoenolpyruvate carboxylase carboxylation rate (V(pmax)). Each side of the leaf therefore exhibits a unique sensitivity to stress and recovery. Side-specific responses to stress are related to differences in the control of enzyme and photosynthetic electron transport activities.

The paleobiological record of photosynthesis

OpenAIRE

William Schopf, J.

2010-01-01

Fossil evidence of photosynthesis, documented in Precambrian sediments by microbially laminated stromatolites, cyanobacterial microscopic fossils, and carbon isotopic data consistent with the presence of Rubisco-mediated CO2-fixation, extends from the present to ~3,500 million years ago. Such data, however, do not resolve time of origin of O2-producing photoautotrophy from its anoxygenic, bacterial, evolutionary precursor. Though it is well established that Earth’s ecosystem has been based on...

Misconception of biology education student of teacher training and education of Sriwijaya University to the concept of photosynthesis and respiration

Science.gov (United States)

Susanti, Rahmi

2018-05-01

This study aimed to gain an overview of misconceptions on the concept of photosynthesis and respiration. The study involved 58 students from Biology Education of Sriwijaya University. Collecting data used written test of 16 questions, which are 10 questions of multiple choice and 6 of choice with reason. The results showed that:photosynthesis occurs continuously (37.9%), energy used for photosynthesis are light and heat energy (34.5%), plants take CO2to respiration (47%), plants carry on respiration in the absence of light for photosynthesis (22.4%), respiration in plants occurs only in leaf cells (76.4%), and only animals that take O2 of photosynthesis to respiration (68.9%). The conclusion: 1) on the concept of photosynthesis is still prevailing misconceptions about the concept of the place and time of the occurrence of photosynthesis in plants, the role of the sun in photosynthesis, energy is required in the form of photosynthesis, and the role of photosynthesis for the plant. 2) on the concept of respiration is still prevailing misconceptions about the place of the respiration in plants, gas necessary for respiration of plants, and the plants perform respiration time, as well as the cycle of CO2 and O2 that occurs in nature.

An apparatus for field measurement of photosynthesis activity in plants using radioactive carbon dioxide

International Nuclear Information System (INIS)

Varshney, O.P.

1994-01-01

An apparatus was designed for rapid and accurate determination of photosynthesis rates in the field. It was standardised with respect to exposure time during which maize leaf was exposed to 14 CO 2 labelled air and the photosynthesis rates were measured

Measurement of solar spectra relating to photosynthesis and solar cells: an inquiry lab for secondary science.

Science.gov (United States)

Ruggirello, Rachel M; Balcerzak, Phyllis; May, Victoria L; Blankenship, Robert E

2012-07-01

The process of photosynthesis is central to science curriculum at all levels. This article describes an inquiry-based laboratory investigation developed to explore the impact of light quality on photosynthesis and to connect this process to current research on harvesting solar energy, including bioenergy, artificial photosynthesis, and solar cells. This laboratory was used with high-school science teachers who then took this experience back to their classrooms. During this exercise, teachers used an economical spectroradiometer to measure the solar spectrum and relate this to photosynthetic light absorption by determining the quality of light beneath trees. Following this investigation, teachers learned about the plant-inspired dye-sensitized solar cells and constructed one. To connect their light quality investigation to the efficiency of photosynthesis and solar cells, teachers then collected data at locations with varying quality and intensity of light. In sum, this investigation provides a crucial connection between photosynthesis and cutting edge research on solar energy technologies. Our learning experience provides a new instructional model for understanding a little investigated aspect of photosynthesis and connects to authentic scientific research. Copyright © 2012 Wiley Periodicals, Inc.

Evaluating potential spectral impacts of various artificial lights on melatonin suppression, photosynthesis, and star visibility.

Directory of Open Access Journals (Sweden)

Martin Aubé

Full Text Available Artificial light at night can be harmful to the environment, and interferes with fauna and flora, star visibility, and human health. To estimate the relative impact of a lighting device, its radiant power, angular photometry and detailed spectral power distribution have to be considered. In this paper we focus on the spectral power distribution. While specific spectral characteristics can be considered harmful during the night, they can be considered advantageous during the day. As an example, while blue-rich Metal Halide lamps can be problematic for human health, star visibility and vegetation photosynthesis during the night, they can be highly appropriate during the day for plant growth and light therapy. In this paper we propose three new indices to characterize lamp spectra. These indices have been designed to allow a quick estimation of the potential impact of a lamp spectrum on melatonin suppression, photosynthesis, and star visibility. We used these new indices to compare various lighting technologies objectively. We also considered the transformation of such indices according to the propagation of light into the atmosphere as a function of distance to the observer. Among other results, we found that low pressure sodium, phosphor-converted amber light emitting diodes (LED and LED 2700 K lamps filtered with the new Ledtech's Equilib filter showed a lower or equivalent potential impact on melatonin suppression and star visibility in comparison to high pressure sodium lamps. Low pressure sodium, LED 5000 K-filtered and LED 2700 K-filtered lamps had a lower impact on photosynthesis than did high pressure sodium lamps. Finally, we propose these indices as new standards for the lighting industry to be used in characterizing their lighting technologies. We hope that their use will favor the design of new environmentally and health-friendly lighting technologies.

Promoting the Understanding of Photosynthesis among Elementary School Student Teachers through Text Design

Science.gov (United States)

Södervik, Ilona; Mikkilä-Erdmann, Mirjamaija; Vilppu, Henna

2014-01-01

The purpose of this study was to investigate elementary school pre-service teachers' understanding of photosynthesis and to examine if a refutational text can support understanding of photosynthesis better than a non-refutational text. A total of 91 elementary school pre-service teachers read either a refutational or a non-refutational text…

Mössbauer spectroscopy in studies of photosynthesis

Science.gov (United States)

Burda, Květoslava

2008-02-01

Photosynthesis is a process occurring in certain species of bacteria, algae and higher plants. It transforms solar energy into various forms of energy-rich organic molecules. Photosystem II (PSII) is the “heart” of the photosynthetic apparatus because it delivers electrons and protons for further steps of the light-driven phases of photosynthesis. There are two enigmatic iron binding structures within the core of photosynthetic apparatus, which play an important role in the electron transfer within PSII. Many investigations focus on the determination of their function which is the key to the understanding of the molecular mechanism of the energy and electron transfer within PSII. Among many methods used in this research field, the Mössbauer spectroscopy is a unique one, which gives the possibility to study changes of the valence and spin states of those two iron sites and the dynamical properties of their protein matrix in the presence of various physiological and stress conditions.

How to Improve the Mastery of Students’ Concept on Photosynthesis Topic?

Science.gov (United States)

Ulfa, K.; Anggraeni, S.; Supriatno, B.

2017-09-01

The PPDP learning strategy in this research is the acronym of Practicum method, Presentation-discussion method, Demonstration method, and Presentation-discussion method. This study aims to describe the effect of applying PPDP learning strategies to mastery of high school students’ concepts on photosynthesis topic. The research method is a weak experiment, with the research design “The One-Group Pretest-Postetst Design”. The implementation of the study involved 35 students in one of the high schools in the city of Palembang. The research instrument used is in the form of test equipment, assessment rubric and questionnaire. Data were analyzed using Microsoft Excel and SPSS 24 Program. The statistical result showed that PPDP learning strategy had an effect on improving conceptual and Effective on the achievement of the value on the minimum criteria set by the school. This is due to the transformation of knowledge from hands-on to minds-on through the discovery of facts about the concept of photosynthesis. This fact leads to the construction of further understanding through cognitive sharing when the activities of the discussions formed similarity and consolidation of the concept of photosynthesis intact. In addition, demonstration activities also cause students’ logic of thinking to develop through observation of factors that may affect the rate of photosynthesis. This PPDP learning strategy can be utilized by teachers in explaining photosynthetic topic.

Continuous background light significantly increases flashing-light enhancement of photosynthesis and growth of microalgae.

Science.gov (United States)

Abu-Ghosh, Said; Fixler, Dror; Dubinsky, Zvy; Iluz, David

2015-01-01

Under specific conditions, flashing light enhances the photosynthesis rate in comparison to continuous illumination. Here we show that a combination of flashing light and continuous background light with the same integrated photon dose as continuous or flashing light alone can be used to significantly enhance photosynthesis and increase microalgae growth. To test this hypothesis, the green microalga Dunaliella salina was exposed to three different light regimes: continuous light, flashing light, and concomitant application of both. Algal growth was compared under three different integrated light quantities; low, intermediate, and moderately high. Under the combined light regime, there was a substantial increase in all algal growth parameters, with an enhanced photosynthesis rate, within 3days. Our strategy demonstrates a hitherto undescribed significant increase in photosynthesis and algal growth rates, which is beyond the increase by flashing light alone. Copyright © 2015 Elsevier Ltd. All rights reserved.

Microscopic heavy-ion theory. Final technical report, June 1, 1993 - May 31, 1996

International Nuclear Information System (INIS)

Ernst, D.J.; Oberacker, V.E.; Umar, A.S.

1998-01-01

In this Final Technical Report, the authors summarize the research activities of the three Principal Investigators (Professors Ernst, Oberacker, and Umar) at Vanderbilt University since the last reporting period through the subject award expiration date (Dec. 31, 1996) under contract DE-FG05-87ER40376 with the Department of Energy. The research effort is divided between the following three areas: nuclear structure and astrophysics (microscopic nuclear structure studies and properties of exotic nuclei at HRIBF, supernovae calculations in connection with nuclear astrophysics, and nuclear viscosity studies via muon-induced fission at PSI); pion and kaon interactions with the nucleus at high energies (interaction of pions and kaons with nuclei from low energies to 1 GeV, propagation of excited hadrons in the nuclear medium as probed by pion and electron induced reactions); nuclear physics at high energies (dynamical string-parton model to study multi-particle production at RHIC, electromagnetic lepton pair production at RHIC)

The Path of Carbon in Photosynthesis XV. Ribulose and Sedoheptulose

Science.gov (United States)

Benson, A. A.; Bassham, J. A.; Calvin, M.; Hall, A. G.; Hirsch, H.; Kawaguchi, S.; Lynch, V.; Tolbert, N. E.

1952-01-01

The intermediates of carbon dioxide reduction by plants include phosphorylated derivatives of hydroxy acids and sugars. Their identification became 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 summarized 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.

Photosynthesis of amphibious and obligately submerged plants in CO2-rich lowland streams.

Science.gov (United States)

Sand-Jensen, Kaj; Frost-Christensen, Henning

1998-11-01

Small unshaded streams in lowland regions receive drainage water with high concentrations of free␣CO 2 , and they support an abundant growth of amphibious and obligately submerged plants. Our first objective was to measure the CO 2 regime during summer in a wide range of small alkaline Danish streams subject to wide variation in temperature, O 2 and CO 2 during the day. The second objective was to determine the effect of these variations on daily changes in light-saturated photosynthesis in water of a homophyllous and a heterophyllous amphibious species that only used CO 2 , and an obligately submerged species capable of using both HCO - 3 and CO 2 . We found that the median CO 2 concentrations of the streams were 11 and 6 times above air saturation in the morning and the afternoon, respectively, but stream sites with dense plant growth had CO 2 concentrations approaching air saturation in the afternoon. In contrast, outlets from lakes had low CO 2 concentrations close to, or below, air saturation. The amphibious species showed a reduction of photosynthesis in water from morning to afternoon along with the decline in CO 2 concentrations, while increasing temperature and O 2 had little effect on photosynthesis. Photosynthesis of the obligately submerged species varied little with the change of CO 2 because of HCO 3 - - use, and variations were mostly due to changes in O 2 concentration. Independent measurements showed that changes in temperature, O 2 and CO 2 could account for the daily variability of photosynthesis of all three species in water. The results imply that CO 2 supersaturation in small lowland streams is important for the rich representation of amphibious species and their contribution to system photosynthesis.

Head Start Impact Study. Technical Report

Science.gov (United States)

Puma, Michael; Bell, Stephen; Cook, Ronna; Heid, Camilla; Shapiro, Gary; Broene, Pam; Jenkins, Frank; Fletcher, Philip; Quinn, Liz; Friedman, Janet; Ciarico, Janet; Rohacek, Monica; Adams, Gina; Spier, Elizabeth

2010-01-01

This Technical Report is designed to provide technical detail to support the analysis and findings presented in the "Head Start Impact Study Final Report" (U.S. Department of Health and Human Services, January 2010). Chapter 1 provides an overview of the Head Start Impact Study and its findings. Chapter 2 provides technical information on the…

Prokaryotic photosynthesis and phototrophy illuminated

DEFF Research Database (Denmark)

Bryant, Donald A; Frigaard, Niels-Ulrik

2006-01-01

Genome sequencing projects are revealing new information about the distribution and evolution of photosynthesis and phototrophy. Although coverage of the five phyla containing photosynthetic prokaryotes (Chlorobi, Chloroflexi, Cyanobacteria, Proteobacteria and Firmicutes) is limited and uneven...... components that have not yet been described. Metagenomics has already shown how the relatively simple phototrophy based upon rhodopsins has spread laterally throughout Archaea, Bacteria and eukaryotes. In this review, we present examples that reflect recent advances in phototroph biology as a result...

Strategies for Efficient Charge Separation and Transfer in Artificial Photosynthesis of Solar Fuels.

Science.gov (United States)

Xu, Yuxing; Li, Ailong; Yao, Tingting; Ma, Changtong; Zhang, Xianwen; Shah, Jafar Hussain; Han, Hongxian

2017-11-23

Converting sunlight to solar fuels by artificial photosynthesis is an innovative science and technology for renewable energy. Light harvesting, photogenerated charge separation and transfer (CST), and catalytic reactions are the three primary steps in the processes involved in the conversion of solar energy to chemical energy (SE-CE). Among the processes, CST is the key "energy pump and delivery" step in determining the overall solar-energy conversion efficiency. Efficient CST is always high priority in designing and assembling artificial photosynthesis systems for solar-fuel production. This Review not only introduces the fundamental strategies for CST but also the combinatory application of these strategies to five types of the most-investigated semiconductor-based artificial photosynthesis systems: particulate, Z-scheme, hybrid, photoelectrochemical, and photovoltaics-assisted systems. We show that artificial photosynthesis systems with high SE-CE efficiency can be rationally designed and constructed through combinatory application of these strategies, setting a promising blueprint for the future of solar fuels. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gaseous NO2 effects on stomatal behavior, photosynthesis and respiration of hybrid poplar leaves

Science.gov (United States)

In this study, we used poplar as a model plant and investigated the effects of gaseous nitrogen dioxide (NO2, 4 microliter per liter) on stomatal conductance, photosynthesis, dark- and photorespiration of Populus alba x Populus berolinensis hybrid leaves using the photosynthesis system and scanning...

Effect of gamma radiation on chlorophylls contents, net photosynthesis and respiration of chlorella pyrenoidosa

International Nuclear Information System (INIS)

Fernandez Gonzalez, J.; Martin Moreno, C.

1983-01-01

The effect of five doses of gamma radiation: 10, 100, 500, 1000 and 5000 Gy on chlorophylls content, net photosynthesis and respiration of chlorella pyrenoidosa has been studied. A decrease in chlorophylls levels is produced after irradiation at 500, 1000 and 5000 Gy, being, at first 'b' chlorophyll affected to a greater extent than 'a' chlorophyll. Net photosynthesis and respiration decline throughout the time of the observations after irradiation, this depressing effect being much more remarkable for the first one. Net photosynthesis inhibition levels of about 30% have got only five hours post irradiation at a dose of 5000 Gy. (author)

Effects of primitive photosynthesis on Earth's early climate system

Science.gov (United States)

Ozaki, Kazumi; Tajika, Eiichi; Hong, Peng K.; Nakagawa, Yusuke; Reinhard, Christopher T.

2018-01-01

The evolution of different forms of photosynthetic life has profoundly altered the activity level of the biosphere, radically reshaping the composition of Earth's oceans and atmosphere over time. However, the mechanistic impacts of a primitive photosynthetic biosphere on Earth's early atmospheric chemistry and climate are poorly understood. Here, we use a global redox balance model to explore the biogeochemical and climatological effects of different forms of primitive photosynthesis. We find that a hybrid ecosystem of H2-based and Fe2+-based anoxygenic photoautotrophs—organisms that perform photosynthesis without producing oxygen—gives rise to a strong nonlinear amplification of Earth's methane (CH4) cycle, and would thus have represented a critical component of Earth's early climate system before the advent of oxygenic photosynthesis. Using a Monte Carlo approach, we find that a hybrid photosynthetic biosphere widens the range of geochemical conditions that allow for warm climate states well beyond either of these metabolic processes acting in isolation. Our results imply that the Earth's early climate was governed by a novel and poorly explored set of regulatory feedbacks linking the anoxic biosphere and the coupled H, C and Fe cycles. We suggest that similar processes should be considered when assessing the potential for sustained habitability on Earth-like planets with reducing atmospheres.

Regulation of Calcium on Peanut Photosynthesis Under Low Night Temperature Stress

Institute of Scientific and Technical Information of China (English)

LIU Yi-fei; HAN Xiao-ri; ZHAN Xiu-mei; YANG Jin-feng; WANG Yu-zhi; SONG Qiao-bo; CHEN Xin

2013-01-01

The effects of different levels of CaCl2 on photosynthesis under low night temperature (8°C) stress in peanuts were studied in order to ifnd out the appropriate concentration of Ca2+ through the artiifcial climate chamber potted culture test. The results indicated that Ca2+, by means of improving the stomatal conductivity of peanut leaves under low night temperature stress, may mitigate the decline of photosynthetic rate in the peanut leaves. The regulation with 15 mmol L-1 CaCl2 (Ca15) was the most effective, compared with other treatments. Subsequently, the improvement of Ca2+ on peanut photosynthesis under low night temperature stress was validated further through spraying withCa15, Ca2+ chelator (ethylene glycol bis(2-aminoethyl) tetraacetic acid; EGTA) and calmodulin antagonists (trilfuonerazine; TFP).And CaM (Ca2+-modulin) played an important role in the nutritional signal transduction for Ca2+ mitigating photosynthesis limitations in peanuts under low night temperature stress.

Crassulacean acid metabolism enhances underwater photosynthesis and diminishes photorespiration in the aquatic plant Isoetes australis

DEFF Research Database (Denmark)

Pedersen, Ole; Rich, S.M.; Pulido Pérez, Cristina

2011-01-01

Underwater photosynthesis by aquatic plants is often limited by low availability of CO2, and photorespiration can be high. Some aquatic plants utilize crassulacean acid metabolism (CAM) photosynthesis. The benefits of CAM for increased underwater photosynthesis and suppression of photorespiration...... photorespiration was evident at a range of O2 concentrations, including values below air equilibrium. At a high O2 concentration of 2.2-fold the atmospheric equilibrium concentration, net photosynthesis was reduced substantially and, although it remained positive in leaves containing high malate concentrations...... were evaluated for Isoetes australis, a submerged plant that inhabits shallow temporary rock pools. • Leaves high or low in malate were evaluated for underwater net photosynthesis and apparent photorespiration at a range of CO2 and O2 concentrations. • CAM activity was indicated by 9.7-fold higher leaf...

Technical advisory panel for the large acceptance spectrometer: Final report

International Nuclear Information System (INIS)

1989-01-01

The Technical Advisory Panel for the Large Acceptance Spectrometer met on November 17--19, 1988, at CEBAF to perform a second review of the status of this project. The charge to the Panel was ''to provide technical advice to the CEBAF directorate on the design, construction, cost, schedule, and implementation of the Large Acceptance Spectrometer.'' In this written report, an overview of the entire project is given. Specific comments on the major components, data handling and analysis, assembly and installation, and management are presented. The Panel's conclusions are contained in the Executive Summary at the beginning of the report

Ecosystem warming does not affect photosynthesis or aboveground autotrophic respiration for boreal black spruce

Energy Technology Data Exchange (ETDEWEB)

Bronson, D.R. [Wyoming Univ., Laramie, WY (United States). Dept. of Renewable Resources; Gower, S.T. [Wisconsin Univ., Madison, WI (United States). Dept. of Forest Ecology and Management

2010-04-15

Substantial increases in climatic temperatures may cause boreal forests to become a carbon source. An improved understanding of the effect of climatic warming on photosynthesis and autotrophic respiration is needed in order to determine the impact of temperature increases on net carbon balances. This study measured the light-saturated photosynthesis foliage respiration and stem respiration of black spruce in heated and control plots during a 3-year period at a site located in Thompson, Manitoba. Greenhouses and soil-heating cables were used to maintain air and soil temperatures at 5 degrees C above ambient air and soil temperatures. Studies were conducted to determine the influence of soil and air warming; soil-only warming; and greenhouses maintained at ambient temperatures. The study showed that treatment differences for photosynthesis, foliage respiration, and stem respiration were not significant over the 3-year period. Results suggested that black spruce may not have significant changes in photosynthesis or respiration rates in warmer climates. 38 refs., 3 tabs., 4 figs.

Role of seagrass photosynthesis in root aerobic processes.

Science.gov (United States)

Smith, R D; Dennison, W C; Alberte, R S

1984-04-01

The role of shoot photosynthesis as a means of supporting aerobic respiration in the roots of the seagrass Zostera marina was examined. O(2) was transported rapidly (10-15 minutes) from the shoots to the root-rhizome tissues upon shoot illumination. The highest rates of transport were in shoots possessing the greatest biomass and leaf area. The rates of O(2) transport do not support a simple gas phase diffusion mechanism. O(2) transport to the root-rhizome system supported aerobic root respiration and in many cases exceeded respiratory requirements leading to O(2) release from the subterranean tissue. Release of O(2) can support aerobic processes in reducing sediments typical of Z. marina habitats. Since the root-rhizome respiration is supported primarily under shoot photosynthetic conditions, then the daily period of photosynthesis determines the diurnal period of root aerobiosis.

Anthocyanin-dependent anoxygenic photosynthesis in coloured flower petals?

Science.gov (United States)

Lysenko, Vladimir; Varduny, Tatyana

2013-11-01

Chlorophylless flower petals are known to be composed of non-photosynthetic tissues. Here, we show that the light energy storage that can be photoacoustically measured in flower petals of Petunia hybrida is approximately 10-12%. We found that the supposed chlorophylless photosynthesis is an anoxygenic, anthocyanin-dependent process occurring in blue flower petals (ADAPFP), accompanied by non-respiratory light-dependent oxygen uptake and a 1.5-fold photoinduced increase in ATP levels. Using a simple, adhesive tape stripping technique, we have obtained a backside image of an intact flower petal epidermis, revealing sword-shaped ingrowths connecting the cell wall and vacuole, which is of interest for the further study of possible vacuole-related photosynthesis. Approaches to the interpretations of ADAPFP are discussed, and we conclude that these results are not impossible in terms of the known photochemistry of anthocyanins.

Ecological Understanding 1: Ways of Experiencing Photosynthesis.

Science.gov (United States)

Carlsson, Britta

2002-01-01

Investigates 10 student teachers' understanding of the different ways in which the function of the ecosystem could be experienced. Explores the functional aspects of the ecosystem using a system approach. Concludes that the idea of transformation is crucial to more complex ways of understanding photosynthesis. (Contains 62 references.) (Author/YDS)

Salinity-dependent limitation of photosynthesis and oxygen exchange in microbial mats

DEFF Research Database (Denmark)

Garcia-Pichel, F.; Kühl, Michael; Nübel, U.

1999-01-01

was specific for each community and in accordance with optimal performance at the respective salinity of origin. This pattern was lost after long-term exposure to varying salinities when responses to salinity were found to approach a general pattern of decreasing photosynthesis and oxygen exchange capacity...... with increasing salinity. Exhaustive measurements of oxygen export in the light, oxygen consumption in the dark and gross photosynthesis indicated that a salinity-dependent limitation of all three parameters occurred. Maximal values for all three parameters decreased exponentially with increasing salinity...

Estimating photosynthesis and concurrent export rates in C3 and C4 species at ambient and elevated CO2

International Nuclear Information System (INIS)

Grodzinski, B.; Jiao, J.; Leonardos, E.D.

1998-01-01

The ability of 21 C3 and C4 monocot and dicot species to rapidly export newly fixed C in the light at both ambient and enriched CO2 levels was compared. Photosynthesis and concurrent export rates were estimated during isotopic equilibrium of the transport sugars using a steady-state 14CO2-labeling procedure. At ambient CO2 photosynthesis and export rates for C3 species were 5 to 15 and 1 to 10 micromole C m-2 s-1, respectively, and 20 to 30 and 15 to 22 micromole C m-2 s-1, respectively, for C4 species. A linear regression plot of export on photosynthesis rate of all species had a correlation coefficient of 0.87. When concurrent export was expressed as a percentage of photosynthesis, several C3 dicots that produced transport sugars other than Suc had high efflux rates relative to photosynthesis, comparable to those of C4 species. At high CO2 photosynthetic and export rates were only slightly altered in C4 species, and photosynthesis increased but export rates did not in all C3 species. The C3 species that had high efflux rates relative to photosynthesis at ambient CO2 exported at rates comparable to those of C4 species on both an absolute basis and as a percentage of photosynthesis. At ambient CO2 there were strong linear relationships between photosynthesis, sugar synthesis, and concurrent export. However, at high CO2 the relationships between photosynthesis and export rate and between sugar synthesis and export rate were not as strong because sugars and starch were accumulated

Temperature effects on respiration and photosynthesis in three diatom-dominated benthic communities

DEFF Research Database (Denmark)

Hancke, Kasper; Glud, R.N.

2004-01-01

ABSTRACT: Short-term temperature effects on respiration and photosynthesis were investigated in intact diatom-dominated benthic communities, collected at 2 temperate and 1 high-arctic subtidal sites. Areal rates of total (TOE) and diffusive (DOE) O2 exchange were determined from O2-microsensor....... This can be ascribed to changes in physical and biological controls during resuspension. Gross photosynthesis was measured with the light-dark shift method at the 2 temperate sites. Both areal (Pgross) and volumetric (Pgross,vol) rates increased with temperature to an optimum temperature at 12 and 15°C......, with a Q10 for Pgross of 2.2 and 2.6 for the 2 sites, respectively. The gross photosynthesis response could be categorised as psychrotrophic for both sites and no temperature adaptation was observed between the 2 sites. Our measurements document that temperature stimulates heterotrophic activity more than...

System-Cost-Optimized Smart EVSE for Residential Application: Final Technical Report including Manufacturing Plan

Energy Technology Data Exchange (ETDEWEB)

Zhu, Charles [Delta Products, Triangle Park, NC (United States)

2015-05-15

In the 2nd quarter of 2012, a program was formally initiated at Delta Products to develop smart-grid-enabled Electric Vehicle Supply Equipment (EVSE) product for residential use. The project was funded in part by the U.S. Department of Energy (DOE), under award DE-OE0000590. Delta products was the prime contractor to DOE during the three year duration of the project. In addition to Delta Products, several additional supplier-partners were engaged in this research and development (R&D) program, including Detroit Edison DTE, Mercedes Benz Research and Development North America, and kVA. This report summarizes the program and describes the key research outcomes of the program. A technical history of the project activities is provided, which describes the key steps taken in the research and the findings made at successive stages in the multi-stage work. The evolution of an EVSE prototype system is described in detail, culminating in prototypes shipped to Department of Energy Laboratories for final qualification. After the program history is reviewed, the key attributes of the resulting EVSE are described in terms of functionality, performance, and cost. The results clearly demonstrate the ability of this EVSE to meet or exceed DOE's targets for this program, including: construction of a working product-intent prototype of a smart-grid-enabled EVSE, with suitable connectivity to grid management and home-energy management systems, revenue-grade metering, and related technical functions; and cost reduction of 50% or more compared to typical market priced EVSEs at the time of DOE's funding opportunity announcement (FOA), which was released in mid 2011. In addition to meeting all the program goals, the program was completed within the original budget and timeline established at the time of the award. The summary program budget and timeline, comparing plan versus actual values, is provided for reference, along with several supporting explanatory notes. Technical

A roadmap for improving the representation of photosynthesis in Earth system models.

Science.gov (United States)

Rogers, Alistair; Medlyn, Belinda E; Dukes, Jeffrey S; Bonan, Gordon; von Caemmerer, Susanne; Dietze, Michael C; Kattge, Jens; Leakey, Andrew D B; Mercado, Lina M; Niinemets, Ülo; Prentice, I Colin; Serbin, Shawn P; Sitch, Stephen; Way, Danielle A; Zaehle, Sönke

2017-01-01

Accurate representation of photosynthesis in terrestrial biosphere models (TBMs) is essential for robust projections of global change. However, current representations vary markedly between TBMs, contributing uncertainty to projections of global carbon fluxes. Here we compared the representation of photosynthesis in seven TBMs by examining leaf and canopy level responses of photosynthetic CO 2 assimilation (A) to key environmental variables: light, temperature, CO 2 concentration, vapor pressure deficit and soil water content. We identified research areas where limited process knowledge prevents inclusion of physiological phenomena in current TBMs and research areas where data are urgently needed for model parameterization or evaluation. We provide a roadmap for new science needed to improve the representation of photosynthesis in the next generation of terrestrial biosphere and Earth system models. No claim to original US Government works New Phytologist © 2016 New Phytologist Trust.

The role of photorespiration during the evolution of C4 photosynthesis in the genus Flaveria.

Science.gov (United States)

Mallmann, Julia; Heckmann, David; Bräutigam, Andrea; Lercher, Martin J; Weber, Andreas P M; Westhoff, Peter; Gowik, Udo

2014-06-16

C4 photosynthesis represents a most remarkable case of convergent evolution of a complex trait, which includes the reprogramming of the expression patterns of thousands of genes. Anatomical, physiological, and phylogenetic and analyses as well as computational modeling indicate that the establishment of a photorespiratory carbon pump (termed C2 photosynthesis) is a prerequisite for the evolution of C4. However, a mechanistic model explaining the tight connection between the evolution of C4 and C2 photosynthesis is currently lacking. Here we address this question through comparative transcriptomic and biochemical analyses of closely related C3, C3-C4, and C4 species, combined with Flux Balance Analysis constrained through a mechanistic model of carbon fixation. We show that C2 photosynthesis creates a misbalance in nitrogen metabolism between bundle sheath and mesophyll cells. Rebalancing nitrogen metabolism requires anaplerotic reactions that resemble at least parts of a basic C4 cycle. Our findings thus show how C2 photosynthesis represents a pre-adaptation for the C4 system, where the evolution of the C2 system establishes important C4 components as a side effect.

Final technical evaluation report for the proposed revised reclamation plan for the Atlas Corporation Moab Mill

International Nuclear Information System (INIS)

1997-03-01

This final Technical Evaluation Report (TER) summarizes the US Nuclear Regulatory Commission staff's review of Atlas Corporation's proposed reclamation plan for its uranium mill tailings pile near Moab, Utah. The proposed reclamation would allow Atlas to (1) reclaim the tailings pile for permanent disposal and long-term custodial care by a government agency in its current location on the Moab site, (2) prepare the site for closure, and (3) relinquish responsibility of the site after having its NRC license terminated. The NRC staff concludes that, subject to license conditions identified in the TER, the proposed reclamation plan meets the requirements identified in NRC regulations, which appear primarily in 10 CFR Part 40. 112 refs., 6 figs., 16 tabs

Final Technical Report - SciDAC Cooperative Agreement: Center for Extended Magnetohydrodynamic Modeling/ Transport and Dynamics in Torodial Fusion System

International Nuclear Information System (INIS)

Schanck, Dalton D.

2010-01-01

Final technical report for research performed by Professor Dalton D. Schnack on SciDAC Cooperative Agreement: Center for Extended MHD Modeling, DE-FC02-06ER54870, for the period 7/1/06 to 2/15/08. Principal results for this period are: 1. Development of a model for computational modeling for the primitive form of the extended MMD equations. This was reported as Phys. Plasmas 13, 058103 (2006). 2. Comparison between the NIMROD and M3D codes for simulation of the nonlinear sawtooth crash in the CDXU tokamak. This was reported in Phys. Plasmas 14, 056105 (2006). 3. Demonstration of 2-fluid and gyroviscous stabilization of interchange modes using computational extended MHD models. This was reported in Phys. Rev. Letters 101, 085005 (2008). Each of these publications is attached as an Appendix of this report. They should be consulted for technical details.

Pectin Methylesterification Impacts the Relationship between Photosynthesis and Plant Growth.

Science.gov (United States)

M Weraduwage, Sarathi; Kim, Sang-Jin; Renna, Luciana; C Anozie, Fransisca; D Sharkey, Thomas; Brandizzi, Federica

2016-06-01

Photosynthesis occurs in mesophyll cells of specialized organs such as leaves. The rigid cell wall encapsulating photosynthetic cells controls the expansion and distribution of cells within photosynthetic tissues. The relationship between photosynthesis and plant growth is affected by leaf area. However, the underlying genetic mechanisms affecting carbon partitioning to different aspects of leaf growth are not known. To fill this gap, we analyzed Arabidopsis plants with altered levels of pectin methylesterification, which is known to modulate cell wall plasticity and plant growth. Pectin methylesterification levels were varied through manipulation of cotton Golgi-related (CGR) 2 or 3 genes encoding two functionally redundant pectin methyltransferases. Increased levels of methylesterification in a line over-expressing CGR2 (CGR2OX) resulted in highly expanded leaves with enhanced intercellular air spaces; reduced methylesterification in a mutant lacking both CGR-genes 2 and 3 (cgr2/3) resulted in thin but dense leaf mesophyll that limited CO2 diffusion to chloroplasts. Leaf, root, and plant dry weight were enhanced in CGR2OX but decreased in cgr2/3. Differences in growth between wild type and the CGR-mutants can be explained by carbon partitioning but not by variations in area-based photosynthesis. Therefore, photosynthesis drives growth through alterations in carbon partitioning to new leaf area growth and leaf mass per unit leaf area; however, CGR-mediated pectin methylesterification acts as a primary factor in this relationship through modulation of the expansion and positioning of the cells in leaves, which in turn drive carbon partitioning by generating dynamic carbon demands in leaf area growth and leaf mass per unit leaf area. © 2016 American Society of Plant Biologists. All Rights Reserved.

Hydrogen sulfide can inhibit and enhance oxygenic photosynthesis in a cyanobacterium from sulfidic springs

NARCIS (Netherlands)

Klatt, Judith M.; Haas, Sebastian; Yilmaz, Pelin; de Beer, Dirk; Polerecky, Lubos

We used microsensors to investigate the combinatory effect of hydrogen sulfide (H2S) and light on oxygenic photosynthesis in biofilms formed by a cyanobacterium from sulfidic springs. We found that photosynthesis was both positively and negatively affected by H2S: (i) H2S accelerated the recovery of

Interactive effects of oxygen, carbon dioxide and flow on photosynthesis and respiration in the scleractinian coral Galaxea fascicularis.

Science.gov (United States)

Osinga, Ronald; Derksen-Hooijberg, Marlous; Wijgerde, Tim; Verreth, Johan A J

2017-06-15

Rates of dark respiration and net photosynthesis were measured for six replicate clonal fragments of the stony coral Galaxea fascicularis (Linnaeus 1767), which were incubated under 12 different combinations of dissolved oxygen (20%, 100% and 150% saturation), dissolved carbon dioxide (9.5 and 19.1 µmol l -1 ) and water flow (1-1.6 versus 4-13 cm s -1 ) in a repeated measures design. Dark respiration was enhanced by increased flow and increased oxygen saturation in an interactive way, which relates to improved oxygen influx into the coral tissue. Oxygen saturation did not influence net photosynthesis: neither hypoxia nor hyperoxia affected net photosynthesis, irrespective of flow and pH, which suggests that hyperoxia does not induce high rates of photorespiration in this coral. Flow and pH had a synergistic effect on net photosynthesis: at high flow, a decrease in pH stimulated net photosynthesis by 14%. These results indicate that for this individual of G. fascicularis , increased uptake of carbon dioxide rather than increased efflux of oxygen explains the beneficial effect of water flow on photosynthesis. Rates of net photosynthesis measured in this study are among the highest ever recorded for scleractinian corals and confirm a strong scope for growth. © 2017. Published by The Company of Biologists Ltd.

GPHS-RTGs in support of the Cassini RTG Program. Addendum to the final technical report, May 1--December 31, 1998

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-12-01

This Addendum to the Cassini GPHS-RTG Program Final Technical Progress Report describes activities performed during the period 1 May 1998 through 31 December 1998, including effort reflecting contract modification M058. These activities include Earth Gravity Assist (EGA) reentry and related analyses which are detailed in Part A, and effort related to the installation of CAGO equipment within Lockheed Martin`s Building 100 facility in Valley Forge, PA, which is detailed in Part B.

GPHS-RTGs in support of the Cassini RTG Program. Addendum to the final technical report, May 1-December 31, 1998

International Nuclear Information System (INIS)

1998-12-01

This Addendum to the Cassini GPHS-RTG Program Final Technical Progress Report describes activities performed during the period 1 May 1998 through 31 December 1998, including effort reflecting contract modification M058. These activities include Earth Gravity Assist (EGA) reentry and related analyses which are detailed in Part A, and effort related to the installation of CAGO equipment within Lockheed Martin's Building 100 facility in Valley Forge, PA, which is detailed in Part B

Exploring the spatial distribution of light interception and photosynthesis of canopies by means of a functional–structural plant model

Science.gov (United States)

Sarlikioti, V.; de Visser, P. H. B.; Marcelis, L. F. M.

2011-01-01

Background and Aims At present most process-based models and the majority of three-dimensional models include simplifications of plant architecture that can compromise the accuracy of light interception simulations and, accordingly, canopy photosynthesis. The aim of this paper is to analyse canopy heterogeneity of an explicitly described tomato canopy in relation to temporal dynamics of horizontal and vertical light distribution and photosynthesis under direct- and diffuse-light conditions. Methods Detailed measurements of canopy architecture, light interception and leaf photosynthesis were carried out on a tomato crop. These data were used for the development and calibration of a functional–structural tomato model. The model consisted of an architectural static virtual plant coupled with a nested radiosity model for light calculations and a leaf photosynthesis module. Different scenarios of horizontal and vertical distribution of light interception, incident light and photosynthesis were investigated under diffuse and direct light conditions. Key Results Simulated light interception showed a good correspondence to the measured values. Explicitly described leaf angles resulted in higher light interception in the middle of the plant canopy compared with fixed and ellipsoidal leaf-angle distribution models, although the total light interception remained the same. The fraction of light intercepted at a north–south orientation of rows differed from east–west orientation by 10 % on winter and 23 % on summer days. The horizontal distribution of photosynthesis differed significantly between the top, middle and lower canopy layer. Taking into account the vertical variation of leaf photosynthetic parameters in the canopy, led to approx. 8 % increase on simulated canopy photosynthesis. Conclusions Leaf angles of heterogeneous canopies should be explicitly described as they have a big impact both on light distribution and photosynthesis. Especially, the vertical

Exploring the spatial distribution of light interception and photosynthesis of canopies by means of a functional-structural plant model.

Science.gov (United States)

Sarlikioti, V; de Visser, P H B; Marcelis, L F M

2011-04-01

At present most process-based models and the majority of three-dimensional models include simplifications of plant architecture that can compromise the accuracy of light interception simulations and, accordingly, canopy photosynthesis. The aim of this paper is to analyse canopy heterogeneity of an explicitly described tomato canopy in relation to temporal dynamics of horizontal and vertical light distribution and photosynthesis under direct- and diffuse-light conditions. Detailed measurements of canopy architecture, light interception and leaf photosynthesis were carried out on a tomato crop. These data were used for the development and calibration of a functional-structural tomato model. The model consisted of an architectural static virtual plant coupled with a nested radiosity model for light calculations and a leaf photosynthesis module. Different scenarios of horizontal and vertical distribution of light interception, incident light and photosynthesis were investigated under diffuse and direct light conditions. Simulated light interception showed a good correspondence to the measured values. Explicitly described leaf angles resulted in higher light interception in the middle of the plant canopy compared with fixed and ellipsoidal leaf-angle distribution models, although the total light interception remained the same. The fraction of light intercepted at a north-south orientation of rows differed from east-west orientation by 10 % on winter and 23 % on summer days. The horizontal distribution of photosynthesis differed significantly between the top, middle and lower canopy layer. Taking into account the vertical variation of leaf photosynthetic parameters in the canopy, led to approx. 8 % increase on simulated canopy photosynthesis. Leaf angles of heterogeneous canopies should be explicitly described as they have a big impact both on light distribution and photosynthesis. Especially, the vertical variation of photosynthesis in canopy is such that the

Connecting Photosynthesis and Cellular Respiration: Preservice Teachers' Conceptions

Science.gov (United States)

Brown, Mary H.; Schwartz, Renee S.

2009-01-01

The biological processes of photosynthesis and plant cellular respiration include multiple biochemical steps, occur simultaneously within plant cells, and share common molecular components. Yet, learners often compartmentalize functions and specialization of cell organelles relevant to these two processes, without considering the interconnections…

Bibliography of reviews and methods of photosynthesis-85

Czech Academy of Sciences Publication Activity Database

Šesták, Zdeněk; Čatský, Jiří

2002-01-01

Roč. 39, č. 4 (2002), s. 615-640 ISSN 0300-3604 R&D Projects: GA AV ČR KSK5020115 Institutional research plan: CEZ:AV0Z5038910 Keywords : methods of photosynthesis Subject RIV: EF - Botanics Impact factor: 0.773, year: 2002

In situ temperature relationships of biochemical and stomatal controls of photosynthesis in four lowland tropical tree species.

Science.gov (United States)

Slot, Martijn; Winter, Klaus

2017-12-01

Net photosynthetic carbon uptake of Panamanian lowland tropical forest species is typically optimal at 30-32 °C. The processes responsible for the decrease in photosynthesis at higher temperatures are not fully understood for tropical trees. We determined temperature responses of maximum rates of RuBP-carboxylation (V CMax ) and RuBP-regeneration (J Max ), stomatal conductance (G s ), and respiration in the light (R Light ) in situ for 4 lowland tropical tree species in Panama. G s had the lowest temperature optimum (T Opt ), similar to that of net photosynthesis, and photosynthesis became increasingly limited by stomatal conductance as temperature increased. J Max peaked at 34-37 °C and V CMax ~2 °C above that, except in the late-successional species Calophyllum longifolium, in which both peaked at ~33 °C. R Light significantly increased with increasing temperature, but simulations with a photosynthesis model indicated that this had only a small effect on net photosynthesis. We found no evidence for Rubisco-activase limitation of photosynthesis. T Opt of V CMax and J Max fell within the observed in situ leaf temperature range, but our study nonetheless suggests that net photosynthesis of tropical trees is more strongly influenced by the indirect effects of high temperature-for example, through elevated vapour pressure deficit and resulting decreases in stomatal conductance-than by direct temperature effects on photosynthetic biochemistry and respiration. © 2017 John Wiley & Sons Ltd.

Applying photosynthesis research to increase crop yields

Science.gov (United States)

Clayton C. Black; Shi-Jean S. Sung; Kristina Toderich; Pavel Yu Voronin

2010-01-01

This account is dedicated to Dr. Guivi Sanadze for his career long devotion to science and in recognition of his discovery of isoprene emission by trees during photosynthesis. Investigations on the emission of isoprene and other monoterpenes now have been extended globally to encompass other terrestrial vegetation, algae, waters, and marine life in the world's...

Photosynthate supply and utilization in alfalfa: a developmental shift from a source to a sink limitation of photosynthesis

International Nuclear Information System (INIS)

Baysdorfer, C.; Bassham, J.A.

1985-01-01

Long-term carbon dioxide enrichment, 14 CO 2 feeding, and partial defoliation were employed as probes to investigate source/sink limitations of photosynthesis during the development of symbiotically grown alfalfa. In the mature crop, long-term CO 2 enrichment does not affect the rates of net photosynthesis, relative growth, 14 C export to nonphotosynthetic organs, or the rates of 14 C label incorporation into leaf sucrose, starch, or malate. The rate of glycolate labeling is, however, substantially reduced under these conditions. When the mature crop was partially defoliated, a considerable increase in net photosynthesis occurred in the remaining leaves. In the seedling crop, long-term CO 2 enrichment increased dry matter accumulation, primarily as a result of increases in leaf starch content. Although the higher rates of starch synthesis are not maintained, the growth enhancement of the enriched plants persisted throughout the experimental period. These results imply a source limitation of seedling photosynthesis and a sink limitation of photosynthesis in more mature plants. Consequently, both the supply and the utilization of photosynthate may limit seasonal photosynthesis in alfalfa

Automated photosynthesis of 11C-glucose

International Nuclear Information System (INIS)

Ishiwata, K.; Monma, M.; Iwata, R.; Ido, T.

1982-01-01

Glucose and fructose, labelled with 11 C, were produced by passing 11 CO 2 into an evacuated chamber containing spinach leaves. Photosynthesis was carried out by day light lamp illumination. 75-95% of the 11 CO 2 was absorbed by the leaves and the radioactivity in the leaves was extracted in ethanol as sugars. Radiochemical purity was determined by HPLC. The automated system was controlled by timers. (U.K.)

Significance of cold-season respiration and photosynthesis in a subarctic heath ecosystem in Northern Sweden

DEFF Research Database (Denmark)

Larsen, Klaus Steenberg; Ibrom, Andreas; Jonasson, S.

2007-01-01

While substantial cold-season respiration has been documented in most arctic and alpine ecosystems in recent years, the significance of cold-season photosynthesis in these biomes is still believed to be small. In a mesic, subartic heath during both the cold and warm season, we measured in situ...... ecosystem respiration and photosynthesis with a chamber technique at ambient conditions and at artificially, increased frequency of freeze-thaw (FT) cycles during fall and spring. We fitted the measured ecosystem exchange rates to respiration and photosynthesis models with R-2-values ranging from 0.81 to 0.......85. As expected, estimated cold-season (October, November, April and May) respiration was significant and accounted for at least 22% of the annual respiratory CO2 flux. More surprisingly, estimated photosynthesis during this period accounted for up to 19% of the annual gross CO2 uptake, suggesting that cold...

Suppression of nighttime sap flux with lower stem photosynthesis in Eucalyptus trees.

Science.gov (United States)

Gao, Jianguo; Zhou, Juan; Sun, Zhenwei; Niu, Junfeng; Zhou, Cuiming; Gu, Daxing; Huang, Yuqing; Zhao, Ping

2016-04-01

It is widely accepted that substantial nighttime sap flux (J s,n) or transpiration (E) occurs in most plants, but the physiological implications are poorly known. It has been hypothesized that J s,n or E serves to enhance nitrogen uptake or deliver oxygen; however, no clear evidence is currently available. In this study, sap flux (J s) in Eucalyptus grandis × urophylla with apparent stem photosynthesis was measured, including control trees which were covered by aluminum foil (approximately 1/3 of tree height) to block stem photosynthesis. We hypothesized that the nighttime water flux would be suppressed in trees with lower stem photosynthesis. The results showed that the green tissue degraded after 3 months, demonstrating a decrease in stem photosynthesis. The daytime J s decreased by 21.47%, while J s,n decreased by 12.03% in covered trees as compared to that of control, and the difference was statistically significant (P photosynthesis in covered trees. Predawn (ψ pd) of covered trees was marginally higher than that of control while lower at predawn stomatal conductance (g s), indicating a suppressed water flux in covered trees. There was no difference in leaf carbon content and δ(13)C between the two groups, while leaf nitrogen content and δ(15)N were significantly higher in covered trees than that of the control (P < 0.05), indicating that J s,n was not used for nitrogen uptake. These results suggest that J s,n may act as an oxygen pathway since green tissue has a higher respiration or oxygen demand than non-green tissue. Thus, this study demonstrated the physiological implications of J s,n and the possible benefits of nighttime water use or E by the tree.

Synthesis of Phenolics and Flavonoids in Ginger (Zingiber officinale Roscoe and Their Effects on Photosynthesis Rate

Directory of Open Access Journals (Sweden)

Asmah Rahmat

2010-11-01

Full Text Available The relationship between phenolics and flavonoids synthesis/accumulation and photosynthesis rate was investigated for two Malaysian ginger (Zingiber officinale varieties grown under four levels of glasshouse light intensity, namely 310, 460, 630 and 790 μmol m−2s−1. High performance liquid chromatography (HPLC was employed to identify and quantify the polyphenolic components. The results of HPLC analysis indicated that synthesis and partitioning of quercetin, rutin, catechin, epicatechin and naringenin were high in plants grown under 310 µmol m−2s−1. The average value of flavonoids synthesis in leaves for both varieties increased (Halia Bentong 26.1%; Halia Bara 19.5% when light intensity decreased. Photosynthetic rate and plant biomass increased in both varieties with increasing light intensity. More specifically, a high photosynthesis rate (12.25 µmol CO2 m−2s−1 in Halia Bara and plant biomass (79.47 g in Halia Bentong were observed at 790 µmol m−2s−1. Furthermore, plants with the lowest rate of photosynthesis had highest flavonoids content. Previous studies have shown that quercetin inhibits and salicylic acid induces the electron transport rate in photosynthesis photosystems. In the current study, quercetin was an abundant flavonoid in both ginger varieties. Moreover, higher concentration of quercetin (1.12 mg/g dry weight was found in Halia Bara leaves grown under 310 µmol m−2s−1 with a low photosynthesis rate. Furthermore, a high content of salicylic acid (0.673 mg/g dry weight was detected in Halia Bara leaves exposed under 790 µmol m−2s−1 with a high photosynthesis rate. No salicylic acid was detected in gingers grown under 310 µmol m−2s−1. Ginger is a semi-shade loving plant that does not require high light intensity for photosynthesis. Different photosynthesis rates at different light intensities may be related to the absence or presence of some flavonoid and phenolic compounds.

Synthesis of Phenolics and Flavonoids in Ginger (Zingiber officinale Roscoe) and Their Effects on Photosynthesis Rate

Science.gov (United States)

Ghasemzadeh, Ali; Jaafar, Hawa Z. E.; Rahmat, Asmah

2010-01-01

The relationship between phenolics and flavonoids synthesis/accumulation and photosynthesis rate was investigated for two Malaysian ginger (Zingiber officinale) varieties grown under four levels of glasshouse light intensity, namely 310, 460, 630 and 790 μmol m−2s−1. High performance liquid chromatography (HPLC) was employed to identify and quantify the polyphenolic components. The results of HPLC analysis indicated that synthesis and partitioning of quercetin, rutin, catechin, epicatechin and naringenin were high in plants grown under 310 μmol m−2s−1. The average value of flavonoids synthesis in leaves for both varieties increased (Halia Bentong 26.1%; Halia Bara 19.5%) when light intensity decreased. Photosynthetic rate and plant biomass increased in both varieties with increasing light intensity. More specifically, a high photosynthesis rate (12.25 μmol CO2 m−2s−1 in Halia Bara) and plant biomass (79.47 g in Halia Bentong) were observed at 790 μmol m−2s−1. Furthermore, plants with the lowest rate of photosynthesis had highest flavonoids content. Previous studies have shown that quercetin inhibits and salicylic acid induces the electron transport rate in photosynthesis photosystems. In the current study, quercetin was an abundant flavonoid in both ginger varieties. Moreover, higher concentration of quercetin (1.12 mg/g dry weight) was found in Halia Bara leaves grown under 310 μmol m−2s−1 with a low photosynthesis rate. Furthermore, a high content of salicylic acid (0.673 mg/g dry weight) was detected in Halia Bara leaves exposed under 790 μmol m−2s−1 with a high photosynthesis rate. No salicylic acid was detected in gingers grown under 310 μmol m−2s−1. Ginger is a semi-shade loving plant that does not require high light intensity for photosynthesis. Different photosynthesis rates at different light intensities may be related to the absence or presence of some flavonoid and phenolic compounds. PMID:21151455

Chloroplastic and stomatal aspects of ozone-induced reduction of net photosynthesis in plants

Energy Technology Data Exchange (ETDEWEB)

Torsethaugen, Gro

1998-09-01

The present thesis relates to ozone-induced reduction of photosynthesis in plants. As a photochemical oxidant O{sub 3} is formed by the interaction of hydrocarbons, nitrogen oxides and oxygen in sunlight. Ozone (O{sub 3}) is the most phytotoxic of all the air pollutants and is known to reduce plant growth and net photosynthesis, cause stomatal closure, induce visible injury, accelerate senescence and induce or inhibit transcription of a variety of genes with a corresponding increase/decrease in protein products. The underlying cellular mechanisms for many of these changes are unknown. Following fields are investigated: Ozone-induced reduction of net photosynthesis; ozone and the photosynthetic apparatus in the chloroplasts; ozone and stomata; ozone effects on plant membranes; protection against ozone injury in plants. 249 refs., 22 figs., 4 tabs.

Effects of high temperature on photosynthesis and related gene expression in poplar

Science.gov (United States)

2014-01-01

Background High temperature, whether transitory or constant, causes physiological, biochemical and molecular changes that adversely affect tree growth and productivity by reducing photosynthesis. To elucidate the photosynthetic adaption response and examine the recovery capacity of trees under heat stress, we measured gas exchange, chlorophyll fluorescence, electron transport, water use efficiency, and reactive oxygen-producing enzyme activities in heat-stressed plants. Results We found that photosynthesis could completely recover after less than six hours of high temperature treatment, which might be a turning point in the photosynthetic response to heat stress. Genome-wide gene expression analysis at six hours of heat stress identified 29,896 differentially expressed genes (15,670 up-regulated and 14,226 down-regulated), including multiple classes of transcription factors. These interact with each other and regulate the expression of photosynthesis-related genes in response to heat stress, controlling carbon fixation and changes in stomatal conductance. Heat stress of more than twelve hours caused reduced electron transport, damaged photosystems, activated the glycolate pathway and caused H2O2 production; as a result, photosynthetic capacity did not recover completely. Conclusions This study provides a systematic physiological and global gene expression profile of the poplar photosynthetic response to heat stress and identifies the main limitations and threshold of photosynthesis under heat stress. It will expand our understanding of plant thermostability and provides a robust dataset for future studies. PMID:24774695

Modular Radioisotope Thermoelectric Generator (RTG) Program. Final technical report

Energy Technology Data Exchange (ETDEWEB)

1992-12-31

Section 2.0 of this report summarizes the MOD-RTG reference flight design, and Section 3.0 discusses the Ground Demonstration System design. Multicouple technology development is discussed in Section 4.0, and Section 5.0 lists all published technical papers prepared during the course of the contract.

Final report on a study of coherence in acceptability criteria for the technical aspects of risks associated with potentially hazardous installations

International Nuclear Information System (INIS)

Chicken, J.C.

1988-01-01

This report describes the results of the study that was made, under Contract No ECI-1390-B7221-85D, for the European Atomic Energy Community. The aim of the study was to examine and assess the feasibility of developing coherent and uniform criteria for judging the acceptability of the technical aspects of the risks associated with potentially hazardous installations. The report is arranged in five main parts. First the nature of hazardous installations is considered and this provides the basis for examination of the currently-used technical risk acceptability criteria. Next, the possible forms of criteria are explored and then universally consistent partial and overall technical risk acceptability criteria are proposed. Following this the implications of using the criteria proposed at the design, regulatory and operating levels are examined. Then, by testing the criteria against some real decisions, the practical problems of using the proposed criteria are explored. This leads to consideration of possible alternatives to the proposed criteria. Finally the conclusions that appear to be justified are summarized and the need for further work is identified

The role of photorespiration during the evolution of C4 photosynthesis in the genus Flaveria

Science.gov (United States)

Mallmann, Julia; Heckmann, David; Bräutigam, Andrea; Lercher, Martin J; Weber, Andreas PM; Westhoff, Peter; Gowik, Udo

2014-01-01

C4 photosynthesis represents a most remarkable case of convergent evolution of a complex trait, which includes the reprogramming of the expression patterns of thousands of genes. Anatomical, physiological, and phylogenetic and analyses as well as computational modeling indicate that the establishment of a photorespiratory carbon pump (termed C2 photosynthesis) is a prerequisite for the evolution of C4. However, a mechanistic model explaining the tight connection between the evolution of C4 and C2 photosynthesis is currently lacking. Here we address this question through comparative transcriptomic and biochemical analyses of closely related C3, C3–C4, and C4 species, combined with Flux Balance Analysis constrained through a mechanistic model of carbon fixation. We show that C2 photosynthesis creates a misbalance in nitrogen metabolism between bundle sheath and mesophyll cells. Rebalancing nitrogen metabolism requires anaplerotic reactions that resemble at least parts of a basic C4 cycle. Our findings thus show how C2 photosynthesis represents a pre-adaptation for the C4 system, where the evolution of the C2 system establishes important C4 components as a side effect. DOI: http://dx.doi.org/10.7554/eLife.02478.001 PMID:24935935

Physiological and Proteomics Analyses Reveal Low-Phosphorus Stress Affected the Regulation of Photosynthesis in Soybean.

Science.gov (United States)

Chu, Shanshan; Li, Hongyan; Zhang, Xiangqian; Yu, Kaiye; Chao, Maoni; Han, Suoyi; Zhang, Dan

2018-06-06

Previous studies have revealed a significant genetic relationship between phosphorus (P)-efficiency and photosynthesis-related traits in soybean. In this study, we used proteome profiling in combination with expression analysis, biochemical investigations, and leaf ultrastructural analysis to identify the underlying physiological and molecular responses. The expression analysis and ultrastructural analysis showed that the photosynthesis key genes were decreased at transcript levels and the leaf mesophyll and chloroplast were severely damaged after low-P stress. Approximately 55 protein spots showed changes under low-P condition by mass spectrometry, of which 17 were involved in various photosynthetic processes. Further analysis revealed the depression of photosynthesis caused by low-P stress mainly involves the regulation of leaf structure, adenosine triphosphate (ATP) synthesis, absorption and transportation of CO₂, photosynthetic electron transport, production of assimilatory power, and levels of enzymes related to the Calvin cycle. In summary, our findings indicated that the existence of a stringent relationship between P supply and the genomic control of photosynthesis in soybean. As an important strategy to protect soybean photosynthesis, P could maintain the stability of cell structure, up-regulate the enzymes’ activities, recover the process of photosystem II (PSII), and induce the expression of low-P responsive genes and proteins.

The Path of Carbon in Photosynthesis

Science.gov (United States)

Bassham, J. A.; Calvin, Melvin

1960-10-01

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.

THE PATH OF CARBON IN PHOTOSYNTHESIS

Energy Technology Data Exchange (ETDEWEB)

Bassham, J.A.; Calvin, Melvin

1960-10-01

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.

Acclimation of biochemical and diffusive components of photosynthesis in rice, wheat and maize to heat and water deficit: implications for modeling photosynthesis

Directory of Open Access Journals (Sweden)

Juan Alejandro Perdomo

2016-11-01

Full Text Available The impact of the combined effects of heat stress, increased vapor pressure deficit (VPD and water deficit on the physiology of major crops needs to be better understood to help identifying the expected negative consequences of climate change and heat waves on global agricultural productivity. To address this issue, rice, wheat and maize plants were grown under control temperature (CT, 25°C, VPD 1.8 kPa, and a high temperature (HT, 38°C, VPD 3.5 kPa, both under well-watered (WW and water deficit (WD conditions. Gas-exchange measurements showed that, in general, WD conditions affected the leaf conductance to CO2, while growth at HT had a more marked effect on the biochemistry of photosynthesis. When combined, HT and WD had an additive effect in limiting photosynthesis. The negative impacts of the imposed treatments on the processes governing leaf gas-exchange were species-dependent. Wheat presented a higher sensitivity while rice and maize showed a higher acclimation potential to increased temperature. Rubisco and PEPC kinetic constants determined in vitro at 25°C and 38°C were used to estimate Vcmax, Jmax and Vpmax in the modeling of C3 and C4 photosynthesis. The results here obtained reiterate the need to use species-specific and temperature-specific values for Rubisco and PEPC kinetic constants for a precise parameterization of the photosynthetic response to changing environmental conditions in different crop species.

Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Howe, Gary [RTI International, Research Triangle Park, NC (United States); Albritton, John [RTI International, Research Triangle Park, NC (United States); Denton, David [RTI International, Research Triangle Park, NC (United States); Turk, Brian [RTI International, Research Triangle Park, NC (United States); Gupta, Raghubir [RTI International, Research Triangle Park, NC (United States)

2018-01-31

technology has great potential to provide clean syngas from coal and petcoke-based gasification at increased efficiency and at significantly lower capital and operating costs than conventional syngas cleanup technologies. However, before the technology can be deemed ready for scale-up to a full commercial-scale demonstration, additional R&D testing is needed at the site to address the following critical technical risks: WDP sorbent stability and performance; Impact of WDP on downstream cleanup and conversion steps; Metallurgy and refractory; Syngas cleanup performance and controllability; Carbon capture performance and additional syngas cleanup The proposed plan to acquire this additional R&D data involves: Operation of the units to achieve an additional 3,000 hours of operation of the system within the performance period, with a target of achieving 1,000 hours of those hours via continuous operation of the entire integrated pre-commercial demonstration system; Rapid turnaround of repairs and/or modifications required as necessary to return any specific unit to operating status with documentation and lessons learned to support technology maturation, and; Proactive performance of maintenance activities during any unplanned outages and if possible while operating.

Elevated Temperature and CO2 Stimulate Late-Season Photosynthesis But Impair Cold Hardening in Pine.

Science.gov (United States)

Chang, Christine Y; Fréchette, Emmanuelle; Unda, Faride; Mansfield, Shawn D; Ensminger, Ingo

2016-10-01

Rising global temperature and CO 2 levels may sustain late-season net photosynthesis of evergreen conifers but could also impair the development of cold hardiness. Our study investigated how elevated temperature, and the combination of elevated temperature with elevated CO 2 , affected photosynthetic rates, leaf carbohydrates, freezing tolerance, and proteins involved in photosynthesis and cold hardening in Eastern white pine (Pinus strobus). We designed an experiment where control seedlings were acclimated to long photoperiod (day/night 14/10 h), warm temperature (22°C/15°C), and either ambient (400 μL L -1 ) or elevated (800 μmol mol -1 ) CO 2 , and then shifted seedlings to growth conditions with short photoperiod (8/16 h) and low temperature/ambient CO 2 (LTAC), elevated temperature/ambient CO 2 (ETAC), or elevated temperature/elevated CO 2 (ETEC). Exposure to LTAC induced down-regulation of photosynthesis, development of sustained nonphotochemical quenching, accumulation of soluble carbohydrates, expression of a 16-kD dehydrin absent under long photoperiod, and increased freezing tolerance. In ETAC seedlings, photosynthesis was not down-regulated, while accumulation of soluble carbohydrates, dehydrin expression, and freezing tolerance were impaired. ETEC seedlings revealed increased photosynthesis and improved water use efficiency but impaired dehydrin expression and freezing tolerance similar to ETAC seedlings. Sixteen-kilodalton dehydrin expression strongly correlated with increases in freezing tolerance, suggesting its involvement in the development of cold hardiness in P. strobus Our findings suggest that exposure to elevated temperature and CO 2 during autumn can delay down-regulation of photosynthesis and stimulate late-season net photosynthesis in P. strobus seedlings. However, this comes at the cost of impaired freezing tolerance. Elevated temperature and CO 2 also impaired freezing tolerance. However, unless the frequency and timing of extreme low

NetView technical research

Science.gov (United States)

1993-01-01

This is the Final Technical Report for the NetView Technical Research task. This report is prepared in accordance with Contract Data Requirements List (CDRL) item A002. NetView assistance was provided and details are presented under the following headings: NetView Management Systems (NMS) project tasks; WBAFB IBM 3090; WPAFB AMDAHL; WPAFB IBM 3084; Hill AFB; McClellan AFB AMDAHL; McClellan AFB IBM 3090; and Warner-Robins AFB.

Rubisco catalytic properties of wild and domesticated relatives provide scope for improving wheat photosynthesis.

Science.gov (United States)

Prins, Anneke; Orr, Douglas J; Andralojc, P John; Reynolds, Matthew P; Carmo-Silva, Elizabete; Parry, Martin A J

2016-03-01

Rubisco is a major target for improving crop photosynthesis and yield, yet natural diversity in catalytic properties of this enzyme is poorly understood. Rubisco from 25 genotypes of the Triticeae tribe, including wild relatives of bread wheat (Triticum aestivum), were surveyed to identify superior enzymes for improving photosynthesis in this crop. In vitro Rubisco carboxylation velocity (V c), Michaelis-Menten constants for CO2 (K c) and O2 (K o) and specificity factor (S c/o) were measured at 25 and 35 °C. V c and K c correlated positively, while V c and S c/o were inversely related. Rubisco large subunit genes (rbcL) were sequenced, and predicted corresponding amino acid differences analysed in relation to the corresponding catalytic properties. The effect of replacing native wheat Rubisco with counterparts from closely related species was analysed by modelling the response of photosynthesis to varying CO2 concentrations. The model predicted that two Rubisco enzymes would increase photosynthetic performance at 25 °C while only one of these also increased photosynthesis at 35 °C. Thus, under otherwise identical conditions, catalytic variation in the Rubiscos analysed is predicted to improve photosynthetic rates at physiological CO2 concentrations. Naturally occurring Rubiscos with superior properties amongst the Triticeae tribe can be exploited to improve wheat photosynthesis and crop productivity. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

NO MECHANISTIC DEPENDENCE OF PHOTOSYNTHESIS ON CALCIFICATION IN THE COCCOLITHOPHORID EMILIANIA HUXLEYI (HAPTOPHYTA)(1).

Science.gov (United States)

Leonardos, Nikos; Read, Betsy; Thake, Brenda; Young, Jeremy R

2009-10-01

There is still considerable uncertainty about the relationship between calcification and photosynthesis. It has been suggested that since calcification in coccolithophorids is an intracellular process that releases CO2 , it enhances photosynthesis in a manner analogous to a carbon-concentrating mechanism (CCM). The ubiquitous, bloom-forming, and numerically abundant coccolithophorid Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler was studied in nutrient-replete, pH and [CO2 ] controlled, continuous cultures (turbidostats) under a range of [Ca(2+) ] from 0 to 9 mM. We examined the long-term, fully acclimated photosynthesis-light responses and analyzed the crystalline structure of the coccoliths using SEM. The E. huxleyi cells completely lost their coccosphere when grown in 0 [Ca(2+) ], while thin, undercalcified and brittle coccoliths were evident at 1 mM [Ca(2+) ]. Coccoliths showed increasing levels of calcification with increasing [Ca(2+) ]. More robust coccoliths were noted, with no discernable differences in coccolith morphology when the cells were grown in either 5 or 9 mM (ambient seawater) [Ca(2+) ]. In contrast to calcification, photosynthesis was not affected by the [Ca(2+) ] in the media. Cells showed no correlation of their light-dependent O2 evolution with [Ca(2+) ], and in all [Ca(2+) ]-containing turbidostats, there were no significant differences in growth rate. The results show unequivocally that as a process, photosynthesis in E. huxleyi is mechanistically independent from calcification. © 2009 Phycological Society of America.

Final technical evaluation report for the proposed revised reclamation plan for the Atlas Corporation Moab Mill

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

This final Technical Evaluation Report (TER) summarizes the US Nuclear Regulatory Commission staff`s review of Atlas Corporation`s proposed reclamation plan for its uranium mill tailings pile near Moab, Utah. The proposed reclamation would allow Atlas to (1) reclaim the tailings pile for permanent disposal and long-term custodial care by a government agency in its current location on the Moab site, (2) prepare the site for closure, and (3) relinquish responsibility of the site after having its NRC license terminated. The NRC staff concludes that, subject to license conditions identified in the TER, the proposed reclamation plan meets the requirements identified in NRC regulations, which appear primarily in 10 CFR Part 40. 112 refs., 6 figs., 16 tabs.

Elevated Temperature and CO2 Stimulate Late-Season Photosynthesis But Impair Cold Hardening in Pine[OPEN

Science.gov (United States)

2016-01-01

Rising global temperature and CO2 levels may sustain late-season net photosynthesis of evergreen conifers but could also impair the development of cold hardiness. Our study investigated how elevated temperature, and the combination of elevated temperature with elevated CO2, affected photosynthetic rates, leaf carbohydrates, freezing tolerance, and proteins involved in photosynthesis and cold hardening in Eastern white pine (Pinus strobus). We designed an experiment where control seedlings were acclimated to long photoperiod (day/night 14/10 h), warm temperature (22°C/15°C), and either ambient (400 μL L−1) or elevated (800 μmol mol−1) CO2, and then shifted seedlings to growth conditions with short photoperiod (8/16 h) and low temperature/ambient CO2 (LTAC), elevated temperature/ambient CO2 (ETAC), or elevated temperature/elevated CO2 (ETEC). Exposure to LTAC induced down-regulation of photosynthesis, development of sustained nonphotochemical quenching, accumulation of soluble carbohydrates, expression of a 16-kD dehydrin absent under long photoperiod, and increased freezing tolerance. In ETAC seedlings, photosynthesis was not down-regulated, while accumulation of soluble carbohydrates, dehydrin expression, and freezing tolerance were impaired. ETEC seedlings revealed increased photosynthesis and improved water use efficiency but impaired dehydrin expression and freezing tolerance similar to ETAC seedlings. Sixteen-kilodalton dehydrin expression strongly correlated with increases in freezing tolerance, suggesting its involvement in the development of cold hardiness in P. strobus. Our findings suggest that exposure to elevated temperature and CO2 during autumn can delay down-regulation of photosynthesis and stimulate late-season net photosynthesis in P. strobus seedlings. However, this comes at the cost of impaired freezing tolerance. Elevated temperature and CO2 also impaired freezing tolerance. However, unless the frequency and timing of extreme low

Preface: photosynthesis and hydrogen energy research for sustainability.

Science.gov (United States)

Tomo, Tatsuya; Allakhverdiev, Suleyman I

2017-09-01

Energy supply, climate change, and global food security are among the main chalenges facing humanity in the twenty-first century. Despite global energy demand is continuing to increase, the availability of low cost energy is decreasing. Together with the urgent problem of climate change due to CO 2 release from the combustion of fossil fuels, there is a strong requirement of developing the clean and renewable energy system for the hydrogen production. Solar fuel, biofuel, and hydrogen energy production gained unlimited possibility and feasibility due to understanding of the detailed photosynthetic system structures. This special issue contains selected papers on photosynthetic and biomimetic hydrogen production presented at the International Conference "Photosynthesis Research for Sustainability-2016", that was held in Pushchino (Russia), during June 19-25, 2016, with the sponsorship of the International Society of Photosynthesis Research (ISPR) and of the International Association for Hydrogen Energy (IAHE). This issue is intended to provide recent information on the photosynthetic and biohydrogen production to our readers.

significance of rice sheath photosynthesis: yield determination by c ...

African Journals Online (AJOL)

ACSS

1State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Changsha 410125, P.R. China. 2School of ... for contribution rates of sheath photosynthesis to economical yield. ..... related processes during ripening in rice plants.

Excess Diffuse Light Absorption in Upper Mesophyll Limits CO2 Drawdown and Depresses Photosynthesis.

Science.gov (United States)

Earles, J Mason; Théroux-Rancourt, Guillaume; Gilbert, Matthew E; McElrone, Andrew J; Brodersen, Craig R

2017-06-01

In agricultural and natural systems, diffuse light can enhance plant primary productivity due to deeper penetration into and greater irradiance of the entire canopy. However, for individual sun-grown leaves from three species, photosynthesis is actually less efficient under diffuse compared with direct light. Despite its potential impact on canopy-level productivity, the mechanism for this leaf-level diffuse light photosynthetic depression effect is unknown. Here, we investigate if the spatial distribution of light absorption relative to electron transport capacity in sun- and shade-grown sunflower ( Helianthus annuus ) leaves underlies its previously observed diffuse light photosynthetic depression. Using a new one-dimensional porous medium finite element gas-exchange model parameterized with light absorption profiles, we found that weaker penetration of diffuse versus direct light into the mesophyll of sun-grown sunflower leaves led to a more heterogenous saturation of electron transport capacity and lowered its CO 2 concentration drawdown capacity in the intercellular airspace and chloroplast stroma. This decoupling of light availability from photosynthetic capacity under diffuse light is sufficient to generate an 11% decline in photosynthesis in sun-grown but not shade-grown leaves, primarily because thin shade-grown leaves similarly distribute diffuse and direct light throughout the mesophyll. Finally, we illustrate how diffuse light photosynthetic depression could overcome enhancement in canopies with low light extinction coefficients and/or leaf area, pointing toward a novel direction for future research. © 2017 American Society of Plant Biologists. All Rights Reserved.

Final priority; technical assistance to improve state data capacity--National Technical Assistance Center to improve state capacity to accurately collect and report IDEA data. Final priority.

Science.gov (United States)

2013-05-20

The Assistant Secretary for Special Education and Rehabilitative Services announces a priority under the Technical Assistance to Improve State Data Capacity program. The Assistant Secretary may use this priority for competitions in fiscal year (FY) 2013 and later years. We take this action to focus attention on an identified national need to provide technical assistance (TA) to States to improve their capacity to meet the data collection and reporting requirements of the Individuals with Disabilities Education Act (IDEA). We intend this priority to establish a TA center to improve State capacity to accurately collect and report IDEA data (Data Center).

Aerobic Anoxygenic Photosynthesis Is Commonly Present within the Genus Limnohabitans.

Science.gov (United States)

Kasalický, Vojtěch; Zeng, Yonghui; Piwosz, Kasia; Šimek, Karel; Kratochvilová, Hana; Koblížek, Michal

2018-01-01

The genus Limnohabitans ( Comamonadaceae , Betaproteobacteria ) is a common and a highly active component of freshwater bacterioplanktonic communities. To date, the genus has been considered to contain only heterotrophic species. In this study, we detected the photosynthesis genes pufLM and bchY in 28 of 46 strains from three Limnohabitans lineages. The pufM sequences obtained are very closely related to environmental pufM sequences detected in various freshwater habitats, indicating the ubiquity and potential importance of photoheterotrophic Limnohabitans in nature. Additionally, we sequenced and analyzed the genomes of 5 potentially photoheterotrophic Limnohabitans strains, to gain further insights into their phototrophic capacity. The structure of the photosynthesis gene cluster turned out to be highly conserved within the genus Limnohabitans and also among all potentially photosynthetic Betaproteobacteria strains. The expression of photosynthetic complexes was detected in a culture of Limnohabitans planktonicus II-D5 T using spectroscopic and pigment analyses. This was further verified by a novel combination of infrared microscopy and fluorescent in situ hybridization. IMPORTANCE The data presented document that the capacity to perform anoxygenic photosynthesis is common among the members of the genus Limnohabitans , indicating that they may have a novel role in freshwater habitats. Copyright © 2017 American Society for Microbiology.

Leaf and canopy photosynthesis of a chlorophyll deficient soybean mutant.

Science.gov (United States)

Sakowska, Karolina; Alberti, Giorgio; Genesio, Lorenzo; Peressotti, Alessandro; Delle Vedove, Gemini; Gianelle, Damiano; Colombo, Roberto; Rodeghiero, Mirco; Panigada, Cinzia; Juszczak, Radosław; Celesti, Marco; Rossini, Micol; Haworth, Matthew; Campbell, Benjamin W; Mevy, Jean-Philippe; Vescovo, Loris; Cendrero-Mateo, M Pilar; Rascher, Uwe; Miglietta, Franco

2018-03-02

The photosynthetic, optical, and morphological characteristics of a chlorophyll-deficient (Chl-deficient) "yellow" soybean mutant (MinnGold) were examined in comparison with 2 green varieties (MN0095 and Eiko). Despite the large difference in Chl content, similar leaf photosynthesis rates were maintained in the Chl-deficient mutant by offsetting the reduced absorption of red photons by a small increase in photochemical efficiency and lower non-photochemical quenching. When grown in the field, at full canopy cover, the mutants reflected a significantly larger proportion of incoming shortwave radiation, but the total canopy light absorption was only slightly reduced, most likely due to a deeper penetration of light into the canopy space. As a consequence, canopy-scale gross primary production and ecosystem respiration were comparable between the Chl-deficient mutant and the green variety. However, total biomass production was lower in the mutant, which indicates that processes other than steady state photosynthesis caused a reduction in biomass accumulation over time. Analysis of non-photochemical quenching relaxation and gas exchange in Chl-deficient and green leaves after transitions from high to low light conditions suggested that dynamic photosynthesis might be responsible for the reduced biomass production in the Chl-deficient mutant under field conditions. © 2018 John Wiley & Sons Ltd.

Radio photosynthesis of some 14 C-labelled sugars using the unicellular green alga scenedesmus ACUTUS

International Nuclear Information System (INIS)

Barakat, M.F.; Farag, A.N.; Ragab, M.T.; El-Fouly, M.M.; El-Baz, F.K.

1993-01-01

Radiosynthesis has been carried out using the unicellular green alga scenedesmus acutus together with Na H 14 CO 3 solution as a carbon-14 source, in an ordinary photosynthesis chamber. The process is more easier and less laborious than the techniques involving the use of gaseous 14 CO 2 in a tight photosynthesis chamber. Uniformly labelled 14 C-glucose, 14 C-fructose and 14 C-sucrose have been prepared with specific activities of several micro curies per milli mole. The specific activity of the products was found to increase on increasing the photosynthesis time or the initial activity of the Na H 14 CO 3 solution used. 3 tabs

Bibliography of reviews and methods of photosynthesis - 88

Czech Academy of Sciences Publication Activity Database

Šesták, Zdeněk; Čatský, Jiří

2004-01-01

Roč. 42, č. 4 (2004), s. 619-640 ISSN 0300-3604 R&D Projects: GA ČR GA206/97/0120 Institutional research plan: CEZ:AV0Z5038910 Keywords : Bibliographic survey * processes of photosynthesis * accumulation of energy Subject RIV: EF - Botanics Impact factor: 0.734, year: 2004

Dynamics of photosynthesis in Eichhornia crassipes Solms of ...

African Journals Online (AJOL)

2009-11-14

With LI-6400 portable photosynthesis system, the photosynthetic characteristics of artificially cultured Eichhornia crassipes in Jiangsu, China, were monitored from June 1 to November 14, 2009. Both the net photosynthetic rate (Pn) in different positions and light and temperature-response curves of the top fourth leaf were ...

Effect of gamma radiation on chlorophylls content, net photosynthesis and respiration of Chlorella pyrenoidosa

International Nuclear Information System (INIS)

Martin Moreno, C.; Fernandez Gonzalez, J.

1983-01-01

The effect of five doses of gamma radiation: 10, 100, 500, 1000 and 5000 Gy on chlorophylls content, net photosynthesis and respiration of Chlorella pyrenoidosa has been studied. A decrease in chlorophylls levels is produced after irradiation at 500, 1000 and 5000 Gy, being, at first b chlorophyll affected to a greater extent than a chlorophyll. Net photosynthesis and respiration decline throughout the time of the observation after irradiation, this depressing effect being much more remarkable for the first one. Met photosynthesis inhibition levels of about 30% are got only five hours post irradiation at a dose of 5000 Gy. Radio estimation by low doses, although obtained in some cases for tho 10 Gy dose, has not been statistically confirmed. (Author) 23 refs

Understanding of photosynthesis among students of biology and non-biology programmes of study

OpenAIRE

Lekan, Erika

2016-01-01

Photosynthesis is one of the most important processes on Earth, thus knowing at least its basic principles is essential. In Slovenia, the students become acquainted with these principles in the fifth form of elementary school. Due to the complexity of the photosynthesis process, the students hold misconceptions about it since the very beginning of the learning process. Due to several factors and reasons, these misconceptions persist throughout the secondary school and university studies. ...

Plants growth, water relations and photosynthesis of two bean ...

African Journals Online (AJOL)

... almost all physiological activities were suppressed. The superiority of the genotype Tema against Djadida genotype was attributed to quantitative rather than qualitative physiological response differences. Keywords: Salinity, fluridone, bean, growth, photosynthesis, stomatal conductance. African Journal of Biotechnology ...

Promotion of Cyclic Electron Transport Around Photosystem I with the Development of C4 Photosynthesis.

Science.gov (United States)

Munekage, Yuri Nakajima; Taniguchi, Yukimi Y

2016-05-01

C4 photosynthesis is present in approximately 7,500 species classified into 19 families, including monocots and eudicots. In the majority of documented cases, a two-celled CO2-concentrating system that uses a metabolic cycle of four-carbon compounds is employed. C4 photosynthesis repeatedly evolved from C3 photosynthesis, possibly driven by the survival advantages it bestows in the hot, often dry, and nutrient-poor soils of the tropics and subtropics. The development of the C4 metabolic cycle greatly increased the ATP demand in chloroplasts during the evolution of malic enzyme-type C4 photosynthesis, and the additional ATP required for C4 metabolism may be produced by the cyclic electron transport around PSI. Recent studies have revealed the nature of cyclic electron transport and the elevation of its components during C4 evolution. In this review, we discuss the energy requirements of C3 and C4 photosynthesis, the current model of cyclic electron transport around PSI and how cyclic electron transport is promoted during C4 evolution using studies on the genus Flaveria, which contains a number of closely related C3, C4 and C3-C4 intermediate species. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

What is the most prominent factor limiting photosynthesis in different layers of a greenhouse cucumber canopy?

NARCIS (Netherlands)

Chen, T.W.; Henke, M.; Visser, de P.H.B.; Buck-Sorlin, G.H.; Wiechers, D.; Kahlen, K.; Stützel, H.

2014-01-01

Background and Aims Maximizing photosynthesis at the canopy level is important for enhancing crop yield, and this requires insights into the limiting factors of photosynthesis. Using greenhouse cucumber (Cucumis sativus) as an example, this study provides a novel approach to quantify different

Comparative sensitivity of photosynthesis and translocation to sulfur dioxide damage in Phaseolus vulgaris L

International Nuclear Information System (INIS)

Noyes, R.D.

1978-01-01

The inhibiting effect of sulfur dioxide on photosynthesis in a mature bean leaf and, simultaneously, on the rate of carbohydrate translocation from this same leaf has been examined. The results show a reduction of 0, 13, and 73% in net photosynthesis and 39, 44, and 69% in translocation, at concentrations of 0.1, 1, and 3 ppm sulfur dioxide, respectively. The inhibition of translocation at 0.1 ppm sulfur dioxide without any accompanying inhibition of net photosynthesis indicates that translocation is considerably more sensitive to sulfur dioxide damage. The mechanism of translocation inhibition at 1 ppm sulfur dioxide or less is shown to be independent of photosynthetic inhibition. Whereas, it is suggested that at higher concentrations significant inhibition of photosynthesis causes an additive reduction of translocation due to reduced levels of transport sugars. Autoradiograms of 14 C-labeled source leaves indicate that one possible mechanism of sulfur dioxide damage to translocation is the inhibition of sieve-tube loading. Inhibition of phloem translocation at common ambient levels (0.1 ppm) of sulfur dioxide is important to the overall growth and yield of major agricultural crops sensitive to sulfur dioxide

Estimating Net Photosynthesis of Biological Soil Crusts in the Atacama Using Hyperspectral Remote Sensing

Directory of Open Access Journals (Sweden)

Lukas W. Lehnert

2018-06-01

Full Text Available Biological soil crusts (BSC encompassing green algae, cyanobacteria, lichens, bryophytes, heterotrophic bacteria and microfungi are keystone species in arid environments because of their role in nitrogen- and carbon-fixation, weathering and soil stabilization, all depending on the photosynthesis of the BSC. Despite their importance, little is known about the BSCs of the Atacama Desert, although especially crustose chlorolichens account for a large proportion of biomass in the arid coastal zone, where photosynthesis is mainly limited due to low water availability. Here, we present the first hyperspectral reflectance data for the most wide-spread BSC species of the southern Atacama Desert. Combining laboratory and field measurements, we establish transfer functions that allow us to estimate net photosynthesis rates for the most common BSC species. We found that spectral differences among species are high, and differences between the background soil and the BSC at inactive stages are low. Additionally, we found that the water absorption feature at 1420 nm is a more robust indicator for photosynthetic activity than the chlorophyll absorption bands. Therefore, we conclude that common vegetation indices must be taken with care to analyze the photosynthesis of BSC with multispectral data.

Electrical Signaling, Photosynthesis and Systemic Acquired Acclimation

Directory of Open Access Journals (Sweden)

Magdalena Szechyńska-Hebda

2017-09-01

Full Text Available Electrical signaling in higher plants is required for the appropriate intracellular and intercellular communication, stress responses, growth and development. In this review, we have focus on recent findings regarding the electrical signaling, as a major regulator of the systemic acquired acclimation (SAA and the systemic acquired resistance (SAR. The electric signaling on its own cannot confer the required specificity of information to trigger SAA and SAR, therefore, we have also discussed a number of other mechanisms and signaling systems that can operate in combination with electric signaling. We have emphasized the interrelation between ionic mechanism of electrical activity and regulation of photosynthesis, which is intrinsic to a proper induction of SAA and SAR. In a special way, we have summarized the role of non-photochemical quenching and its regulator PsbS. Further, redox status of the cell, calcium and hydraulic waves, hormonal circuits and stomatal aperture regulation have been considered as components of the signaling. Finally, a model of light-dependent mechanisms of electrical signaling propagation has been presented together with the systemic regulation of light-responsive genes encoding both, ion channels and proteins involved in regulation of their activity. Due to space limitations, we have not addressed many other important aspects of hormonal and ROS signaling, which were presented in a number of recent excellent reviews.

Relationships between net photosynthesis and foliar nitrogen concentrations in a loblobby pine forest ecosystem grown in elevated atmospheric carbon dioxide

International Nuclear Information System (INIS)

Springer, C. J.; Thomas, R. B.; Delucia, E. H.

2005-01-01

The effects of elevated carbon dioxide concentration on the relationship between light-saturated net photosynthesis and area-based foliar nitrogen concentration in the canopy of a loblobby pine forest at the Duke Forest FACE experiment was examined. Two overstory and four understory tree species were examined at their growth carbon dioxide concentrations during the early summer and late summer of 1999, 2001 and 2002. Light-saturated net photosynthesis and foliar nitrogen relationship were compared to determine if the stimulatory effects of elevated carbon dioxide on net photosynthesis had declined. Results at all three sample times showed no difference in either the slopes, or in the y-intercepts of the net photosynthesis-foliar nitrogen relationship when measured at common carbon dioxide concentrations. Net photosynthesis was also unaffected by growth in elevated carbon dioxide, indicating that these overstory and understory trees continued to show strong stimulation of photosynthesis by elevated carbon dioxide. 46 refs., 6 tabs., 3 figs

Vegetation Function and Physiology: Photosynthesis, Fluorescence and Non-photochemical Quenching (NPQ)

Science.gov (United States)

Zhang, Q.; Yao, T.

2017-12-01

Photosynthesis is a basic physiological function of vegetation that relies on PAR provided through photosynthetic pigments (mainly chlorophyll) for plant growth and biomass accumulation. Vegetation chlorophyll (chl) content and non-chlorophyll (non-chl) components vary with plant functional types (PFTs) and growing stages. The PAR absorbed by canopy chlorophyll (APARchl) is associated with photosynthesis (i.e., gross primary production, GPP) while the PAR absorbed by canopy non-chl components (APARnon-chl) is not associated with photosynthesis. Under non-optimal environmental conditions, vegetation is "stressed" and both photosynthesis (GPP) and light use efficiency are reduced, therefore, excess portions of APARchl are discarded as fluorescence or non-photochemical quenching (NPQ). The photochemical reflectance index (PRI) is a measurement related to NPQ. Both PRI and yield of solar induced chlorophyll fluorescence (SIFyield = SIF/APARchl) have been proposed as possible bio-indicators of LUEchl. We have successfully developed an algorithm to distinguish between chlorophyll and non-chl components of vegetation, and to retrieve fractional absorptions of PAR by chlorophyll (fAPARchl) and by non-chl components (fAPARnon-chl) with surface reflectance of MODIS bands 1 - 7. A method originally pioneered by Hanan et al. (2002) has been used to retrieve fAPAR for vegetation photosynthesis (fAPARPSN) at flux tower sites based on the light response curve of tower net ecosystem exchange (NEE) and incident PAR at low light intensity. We have also retrieved the PRI from MODIS data (bands 11 and 1) and have derived SIFyield with the Global Ozone Monitoring Experiment - 2 (GOME-2) SIF data. We find that fAPARPSN at flux tower sites matches well with site fAPARchl, and ratio fAPARnon-chl/fAPARchl varies largely. APARchl can explain >=78% variation in seasonal GPP . We disentangle the possible impact of fAPARchl on PRI from physiological stress response, disentangle the possible

Carbohydrate regulation of photosynthesis and respiration from branch girdling in four species of wet tropical rain forest trees.

Science.gov (United States)

Asao, Shinichi; Ryan, Michael G

2015-06-01

How trees sense source-sink carbon balance remains unclear. One potential mechanism is a feedback from non-structural carbohydrates regulating photosynthesis and removing excess as waste respiration when the balance of photosynthesis against growth and metabolic activity changes. We tested this carbohydrate regulation of photosynthesis and respiration using branch girdling in four tree species in a wet tropical rainforest in Costa Rica. Because girdling severs phloem to stop carbohydrate export while leaving xylem intact to allow photosynthesis, we expected carbohydrates to accumulate in leaves to simulate a carbon imbalance. We varied girdling intensity by removing phloem in increments of one-quarter of the circumference (zero, one--quarter, half, three-quarters, full) and surrounded a target branch with fully girdled ones to create a gradient in leaf carbohydrate content. Light saturated photosynthesis rate was measured in situ, and foliar respiration rate and leaf carbohydrate content were measured after destructive harvest at the end of the treatment. Girdling intensity created no consistent or strong responses in leaf carbohydrates. Glucose and fructose slightly increased in all species by 3.4% per one-quarter girdle, total carbon content and leaf mass per area increased only in one species by 5.4 and 5.5% per one-quarter girdle, and starch did not change. Only full girdling lowered photosynthesis in three of four species by 59-69%, but the decrease in photosynthesis was unrelated to the increase in glucose and fructose content. Girdling did not affect respiration. The results suggest that leaf carbohydrate content remains relatively constant under carbon imbalance, and any changes are unlikely to regulate photosynthesis or respiration. Because girdling also stops the export of hormones and reactive oxygen species, girdling may induce physiological changes unrelated to carbohydrate accumulation and may not be an effective method to study carbohydrate feedback

2012 Photosynthesis Gordon Research Conference and Seminar, JUL 7-13, 2012

Energy Technology Data Exchange (ETDEWEB)

Debus, Richard [Univ. of California, Riverside, CA (United States)

2012-07-13

The Gordon Research Conference on PHOTOSYNTHESIS was held at Davidson College, Davidson, North Carolina, July 8-13, 2012. The Conference was well-attended with 150 participants (attendees list attached). The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students. Of the 150 attendees, 65 voluntarily responded to a general inquiry regarding ethnicity which appears on our registration forms. Of the 65 respondents, 20% were Minorities$-$ 5% Hispanic, 15% Asian and 0% African American. Approximately 28% of the participants at the 2012 meeting were women. The Gordon Research Seminar on PHOTOSYNTHESIS held at Davidson College, Davidson, North Carolina, July 7-8, 2012.. The Conference was well-attended with 51 participants (attendees list attached). The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students. Of the 51 attendees, 22 voluntarily responded to a general inquiry regarding ethnicity which appears on our registration forms. Of the 22 respondents, 14% were Minorities $-$0% Hispanic, 14% Asian and 0% African American. Approximately 35% of the participants at the 2012 meeting were women. Focal points for talks and discussions will include: Artificial photosynthesis and solar energy conversion strategies; Engineering organisms for biofuels and hydrogen production; Electron transport, proton transport, and energy coupling; Photoprotection mechanisms; Photosynthetic reaction center structure and function, including rewiring reaction centers for artificial photosynthesis; Energy capture and light harvesting solutions, including quantum coherence; Structure of the oxygen evolving complex and the mechanism of oxygen production.

Future Elementary School Teachers' Conceptual Change Concerning Photosynthesis

Science.gov (United States)

Ahopelto, Ilona; Mikkila-Erdmann, Mirjamaija; Anto, Erkki; Penttinen, Marjaana

2011-01-01

The purpose of this study was to examine conceptual change among future elementary school teachers while studying a scientific text concerning photosynthesis. Students' learning goals in relation to their learning outcomes were also examined. The participants were future elementary school teachers. The design consisted of pre- and post-tests. The…

Photosynthesis versus irradiance relationships in the Atlantic sector ...

African Journals Online (AJOL)

The results show substantial variability in the photosynthesis–irradiance (P vs E) parameters, with phytoplankton communities at stations that were considered iron (Fe)-limited showing low maximum photosynthetic capacity (PBmax) and low quantum efficiency of photosynthesis (αB) for ρNO3, but high PBmax and αB for ...

Significance of rice sheath photosynthesis: Yield determination by ...

African Journals Online (AJOL)

Using high-yielding hybrid rice Liangyopeijiu (LYP9), its male parent 9311 and hybrid rice Shanyou 63 (SY63) as the experimental materials, the photosynthesis of rice sheath was studied by 14C radio-autography. The results showed that rice sheath could trap sunlight and produce photosynthates, and these ...

Interaction of two photoreceptors in the regulation of bacterial photosynthesis genes.

Science.gov (United States)

Metz, Sebastian; Haberzettl, Kerstin; Frühwirth, Sebastian; Teich, Kristin; Hasewinkel, Christian; Klug, Gabriele

2012-07-01

The expression of photosynthesis genes in the facultatively photosynthetic bacterium Rhodobacter sphaeroides is controlled by the oxygen tension and by light quantity. Two photoreceptor proteins, AppA and CryB, have been identified in the past, which are involved in this regulation. AppA senses light by its N-terminal BLUF domain, its C-terminal part binds heme and is redox-responsive. Through its interaction to the transcriptional repressor PpsR the AppA photoreceptor controls expression of photosynthesis genes. The cryptochrome-like protein CryB was shown to affect regulation of photosynthesis genes, but the underlying signal chain remained unknown. Here we show that CryB interacts with the C-terminal domain of AppA and modulates the binding of AppA to the transcriptional repressor PpsR in a light-dependent manner. Consequently, binding of the transcription factor PpsR to its DNA target is affected by CryB. In agreement with this, all genes of the PpsR regulon showed altered expression levels in a CryB deletion strain after blue-light illumination. These results elucidate for the first time how a bacterial cryptochrome affects gene expression.

The regulation of the chloroplast proton motive force plays a key role for photosynthesis in fluctuating light.

Science.gov (United States)

Armbruster, Ute; Correa Galvis, Viviana; Kunz, Hans-Henning; Strand, Deserah D

2017-06-01

Plants use sunlight as their primary energy source. During photosynthesis, absorbed light energy generates reducing power by driving electron transfer reactions. These are coupled to the transfer of protons into the thylakoid lumen, generating a proton motive force (pmf) required for ATP synthesis. Sudden alterations in light availability have to be met by regulatory mechanisms to avoid the over-accumulation of reactive intermediates and maximize energy efficiency. Here, the acidification of the lumen, as an intermediate product of photosynthesis, plays an important role by regulating photosynthesis in response to excitation energy levels. Recent findings reveal pmf regulation and the modulation of its composition as key determinants for efficient photosynthesis, plant growth, and survival in fluctuating light environments. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Yucca Mountain Climate Technical Support Representative

International Nuclear Information System (INIS)

Sharpe, Saxon E

2007-01-01

The primary objective of Project Activity ORD-FY04-012, 'Yucca Mountain Climate Technical Support Representative', was to provide the Office of Civilian Radioactive Waste Management (OCRWM) with expertise on past, present, and future climate scenarios and to support the technical elements of the Yucca Mountain Project (YMP) climate program. The Climate Technical Support Representative was to explain, defend, and interpret the YMP climate program to the various audiences during Site Recommendation and License Application. This technical support representative was to support DOE management in the preparation and review of documents, and to participate in comment response for the Final Environmental Impact Statement, the Site Recommendation Hearings, the NRC Sufficiency Comments, and other forums as designated by DOE management. Because the activity was terminated 12 months early and experience a 27% reduction in budget, it was not possible to complete all components of the tasks as originally envisioned. Activities not completed include the qualification of climate datasets and the production of a qualified technical report. The following final report is an unqualified summary of the activities that were completed given the reduced time and funding

Effects of light intensity on the morphology and CAM photosynthesis of Vanilla planifolia Andrews

Directory of Open Access Journals (Sweden)

María Claudia Díez

2017-01-01

Full Text Available Vanilla planifolia is a neotropical orchid, whose fruits produce the natural vanilla, a fundamental ingredient for the food and cosmetic industry. Because of its importance in the world market, it is cultivated in many tropical countries and recently its cultivation has started in Colombia. This species requires shade for its development; however, the optimal of light conditions are unknown. This work evaluates the effect of different light intensities on CAM photosynthesis, physiology, morphology, and growth of this species. For this, vanilla seedlings were subjected to four treatments of relative illumination (RI (T1=8%, T2=17%, T3=31% and T4=67%. Most CO2 assimilation occurred along night in all treatments, which confirms that vanilla is a strong CAM species. Plants grown under high lighting (67% RI had almost half of the photosynthesis in treatments of intermediate lighting (17 and 31%, which is consistent with the lower nocturnal acid accumulation in that treatment. Likewise, the photochemical efficiency of photosystem II (Fv / Fm showed that in plants of the 67% RI occurred high radiation stress. On the other hand, vanilla plants reached greater length, leaf area, and total biomass when grown under intermediate radiation (17 and 31% RI. These results suggest that high radiation alters the functioning of vanilla plants, inhibiting photosynthesis and growth, and that highly shaded environments not significantly affected the CAM photosynthesis of vanilla; however, in the long-term this species showed higher photosynthesis and growth under intermediate levels of radiation

Modelling basin-wide variations in Amazon forest photosynthesis

Science.gov (United States)

Mercado, Lina; Lloyd, Jon; Domingues, Tomas; Fyllas, Nikolaos; Patino, Sandra; Dolman, Han; Sitch, Stephen

2010-05-01

Given the importance of Amazon rainforest in the global carbon and hydrological cycles, there is a need to use parameterized and validated ecosystem gas exchange and vegetation models for this region in order to adequately simulate present and future carbon and water balances. Recent research has found major differences in above-ground net primary productivity (ANPP), above ground biomass and tree dynamics across Amazonia. West Amazonia is more dynamic, with younger trees, higher stem growth rates and lower biomass than central and eastern Amazon (Baker et al. 2004; Malhi et al. 2004; Phillips et al. 2004). A factor of three variation in above-ground net primary productivity has been estimated across Amazonia by Malhi et al. (2004). Different hypotheses have been proposed to explain the observed spatial variability in ANPP (Malhi et al. 2004). First, due to the proximity to the Andes, sites from western Amazonia tend to have richer soils than central and eastern Amazon and therefore soil fertility could possibly be highly related to the high wood productivity found in western sites. Second, if GPP does not vary across the Amazon basin then different patterns of carbon allocation to respiration could also explain the observed ANPP gradient. However since plant growth depends on the interaction between photosynthesis, transport of assimilates, plant respiration, water relations and mineral nutrition, variations in plant gross photosynthesis (GPP) could also explain the observed variations in ANPP. In this study we investigate whether Amazon GPP can explain variations of observed ANPP. We use a sun and shade canopy gas exchange model that has been calibrated and evaluated at five rainforest sites (Mercado et al. 2009) to simulate gross primary productivity of 50 sites across the Amazon basin during the period 1980-2001. Such simulation differs from the ones performed with global vegetation models (Cox et al. 1998; Sitch et al. 2003) where i) single plant functional

Systems study 'Alternative Entsorgung'. Final report. Technical annex 6

International Nuclear Information System (INIS)

1984-08-01

In the conditioning plant, fuel elements which have been stored for ten years are loaded into transport containers, unloaded, identified and welded into a dry storage box. The dry store barrel is introduced into a final storage container, which, after being closed, is packed in lost shielding. This so-called final storage barrel is finally placed in a transport container and leaves the conditioning plant in this form by rail for transport to the final storage mine. The fuel element method of treatment 'packing of three complete fuel elements' was used as the reference process. In addition, the method of treatment 'fuel elements dismantled into fuel rods' was also examined. The handling of fuel elements and secondary waste treatment in the reference process are described in detail. (orig./HP) [de

Effects of iron limitation on photosynthesis and carbohydrate metabolism in the Antarctic diatom Chaetoceros brevis (Bacillariophyceae)

NARCIS (Netherlands)

van Oijen, T; van Leeuwe, MA; Gieskes, WWC; de Baar, HJW

Iron, one of the structural elements of organic components that play an essential role in photosynthesis and nitrogen assimilation of plants, is available at extremely low concentrations in large parts of the Southern Ocean's surface waters. We tested the hypothesis that photosynthesis is the

Estimation of effects of photosynthesis response functions on rice yields and seasonal variation of CO2 fixation using a photosynthesis-sterility type of crop yield model

International Nuclear Information System (INIS)

Kaneko, D.; Moriwaki, Y.

2008-01-01

This study presents a crop production model improvement: the previously adopted Michaelis-Menten (MM) type photosynthesis response function (fsub(rad-MM)) was replaced with a Prioul-Chartier (PC) type function (fsub(rad-PC)). The authors' analysis reflects concerns regarding the background effect of global warming, under simultaneous conditions of high air temperature and strong solar radiation. The MM type function fsub(rad-MM) can give excessive values leading to an overestimate of photosynthesis rate (PSN) and grain yield for paddy-rice. The MM model is applicable to many plants whose (PSN) increases concomitant with increased insolation: wheat, maize, soybean, etc. For paddy rice, the PSN apparently shows a maximum PSN. This paper proves that the MM model overestimated the PSN for paddy rice for sufficient solar radiation: the PSN using the PC model yields 10% lower values. However, the unit crop production index (CPIsub(U)) is almost independent of the MM and PC models because of respective standardization of both PSN and crop production index using average PSNsub(0) and CPIsub(0). The authors improved the estimation method using a photosynthesis-and-sterility based crop situation index (CSIsub(E)) to produce a crop yield index (CYIsub(E)), which is used to estimate rice yields in place of the crop situation index (CSI); the CSI gives a percentage of rice yields compared to normal annual production. The model calculates PSN including biomass effects, low-temperature sterility, and high-temperature injury by incorporating insolation, effective air temperature, the normalized difference vegetation index (NDVI), and effects of temperature on photosynthesis. Based on routine observation data, the method enables automated crop-production monitoring in remote regions without special observations. This method can quantify grain production early to raise an alarm in Southeast Asian countries, which must confront climate fluctuation through this era of global

Ecosystem Phenology from Eddy-covariance Measurements: Spring Photosynthesis in a Cool Temperate Bog

Science.gov (United States)

Lafleur, P.; Moore, T. R.; Poon, D.; Seaquist, J.

2005-12-01

The onset and increase of spring photosynthetic flux of carbon dioxide is an important attribute of the carbon budget of northern ecosystems and we used eddy-covariance measurements from March to May over 5 years at the Mer Bleue ombrotrophic bog to establish the important controls. The onset of ecosystem photosynthesis (day-of-year from 86 to 101) was associated with the disappearance on the snow cover and there is evidence that photosynthesis can continue after a thin new snowfall. The growth of photosynthesis during the spring period was partially associated with light (daily photosynthetically active radiation) but primarily with temperature, with the strongest correlation being observed with peat temperature at a depth of 5 and 10 cm, except in one year in which there was a long snow cover. The vegetation comprises mosses, which are able to photosynthesize very early, evergreen shrubs, which appear dependent on soil warming, and deciduous shrubs, which leaf-out only in late spring. We observed changes in shrub leaf colour from brown to green and concomitant increases in foliar nitrogen and chlorophyll concentrations during the spring in this "evergreen" system. We analyzed MODIS images for periods of overlap of tower and satellite data and found a generally strong correlation, though the infrequent satellite measurements were unable to pick out the onset and timing of rapid growth of photosynthesis in this ecosystem.

Photosynthesis by isolated chloroplasts. IV. General concept and comparison of three photochemical reactions

Energy Technology Data Exchange (ETDEWEB)

Arnon, D I; Allen, M B; Whatley, F R

1956-01-01

Procedures are described for the preparation of chloroplasts capable of carrying out three photochemical reactions, each representing an increasingly complex phase of photosynthesis: photolysis of water (Hill reaction), esterification of inorganic phosphate into adenosine triphosphate (photosynthetic phosphorylation) and the reduction of carbon dioxide to the level of carbohydrates with a simultaneous evolution of oxygen. The three photochemical reactions were separable by variations in the technique for preparation of chloroplasts and by differential inhibition by several reagents. Inhibition of a more complex phase of photosynthesis does not affect the simpler one which precedes it and, conversely, the inhibition of a simpler phase of photosynthesis is paralleled by an inhibition of the more complex phase which follows. Reversible inhibition of CO/sub 2/ fixation and photosynthetic phosphorylation, but not of photolysis, by sulfhydryl group inhibitors suggests that sulfhydryl compounds (enzymes, cofactors, or both) are involved in phosphorylation and CO/sub 2/ fixation, but not in the primary conversion of light into chemical energy as measured by the Hill reaction. Evidence is presented in support of the conclusion that the synthesis of ATP by green cells occurs at two distinct sites: anaerobically in chloroplasts by photosynthetic phosphorylation, and acrobically in smaller cytoplasmic particles, presumably mitochondria, by oxidative phosphorylation independent of light. A general scheme of photosynthesis by chloroplasts, consistent with these findings, is presented. 44 references, 8 figures, 4 tables.

IRIS Final Technical Progress Report

Energy Technology Data Exchange (ETDEWEB)

M. D. Carelli

2003-11-03

OAK-B135 This NERI project, originally started as the Secure Transportable Autonomous Light Water Reactor (STAR-LW) and currently known as the International Reactor Innovative and Secure (IRIS) project, had the objective of investigating a novel type of water-cooled reactor to satisfy the Generation IV goals: fuel cycle sustainability, enhanced reliability and safety, and improved economics. The research objectives over the three-year (1999-2002) program were as follows: First year: Assess various design alternatives and establish main characteristics of a point design; Second year: Perform feasibility and engineering assessment of the selected design solutions; Third year: Complete reactor design and performance evaluation, including cost assessment These objectives were fully attained and actually they served to launch IRIS as a full fledged project for eventual commercial deployment. The program did not terminate in 2002 at the end of the NERI program, and has just entered in its fifth year. This has been made possible by the IRIS project participants which have grown from the original four member, two-countries team to the current twenty members, nine countries consortium. All the consortium members work under their own funding and it is estimated that the value of their in-kind contributions over the life of the project has been of the order of $30M. Currently, approximately 100 people worldwide are involved in the project. A very important constituency of the IRIS project is the academia: 7 universities from four countries are members of the consortium and five more US universities are associated via parallel NERI programs. To date, 97 students have worked or are working on IRIS; 59 IRIS-related graduate theses have been prepared or are in preparation, and 41 of these students have already graduated with M.S. (33) or Ph.D. (8) degrees. This ''final'' report (final only as far as the NERI program is concerned) summarizes the work performed

Inorganic carbon availability in benthic diatom communities: photosynthesis and migration.

Science.gov (United States)

Marques da Silva, Jorge; Cruz, Sónia; Cartaxana, Paulo

2017-09-05

Diatom-dominated microphytobenthos (MPB) is the main primary producer of many intertidal and shallow subtidal environments, being therefore of critical importance to estuarine and coastal food webs. Owing to tidal cycles, intertidal MPB diatoms are subjected to environmental conditions far more variable than the ones experienced by pelagic diatoms (e.g. light, temperature, salinity, desiccation and nutrient availability). Nevertheless, benthic diatoms evolved adaptation mechanisms to these harsh conditions, including the capacity to move within steep physical and chemical gradients, allowing them to perform photosynthesis efficiently. In this contribution, we will review present knowledge on the effects of dissolved inorganic carbon (DIC) availability on photosynthesis and productivity of diatom-dominated MPB. We present evidence of carbon limitation of photosynthesis in benthic diatom mats and highly productive MPB natural communities. Furthermore, we hypothesize that active vertical migration of epipelic motile diatoms could overcome local depletion of DIC in the photic layer, providing the cells alternately with light and inorganic carbon supply. The few available longer-term experiments on the effects of inorganic carbon enrichment on the productivity of diatom-dominated MPB have yielded inconsistent results. Therefore, further studies are needed to properly assess the response of MPB communities to increased CO 2 and ocean acidification related to climate change.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'. © 2017 The Author(s).

Chlorophyll fluorescence tracks seasonal variations of photosynthesis from leaf to canopy in a temperate forest.

Science.gov (United States)

Yang, Hualei; Yang, Xi; Zhang, Yongguang; Heskel, Mary A; Lu, Xiaoliang; Munger, J William; Sun, Shucun; Tang, Jianwu

2017-07-01

Accurate estimation of terrestrial gross primary productivity (GPP) remains a challenge despite its importance in the global carbon cycle. Chlorophyll fluorescence (ChlF) has been recently adopted to understand photosynthesis and its response to the environment, particularly with remote sensing data. However, it remains unclear how ChlF and photosynthesis are linked at different spatial scales across the growing season. We examined seasonal relationships between ChlF and photosynthesis at the leaf, canopy, and ecosystem scales and explored how leaf-level ChlF was linked with canopy-scale solar-induced chlorophyll fluorescence (SIF) in a temperate deciduous forest at Harvard Forest, Massachusetts, USA. Our results show that ChlF captured the seasonal variations of photosynthesis with significant linear relationships between ChlF and photosynthesis across the growing season over different spatial scales (R 2  = 0.73, 0.77, and 0.86 at leaf, canopy, and satellite scales, respectively; P chlorophyll content (R 2  = 0.65 for canopy GPP SIF and chlorophyll content; P < 0.0001), leaf area index (LAI) (R 2  = 0.35 for canopy GPP SIF and LAI; P < 0.0001), and normalized difference vegetation index (NDVI) (R 2  = 0.36 for canopy GPP SIF and NDVI; P < 0.0001). Our results suggest that ChlF can be a powerful tool to track photosynthetic rates at leaf, canopy, and ecosystem scales. © 2016 John Wiley & Sons Ltd.

The potential feasibility of chlorinic photosynthesis on exoplanets.

Science.gov (United States)

Haas, Johnson R

2010-11-01

The modern search for life-bearing exoplanets emphasizes the potential detection of O(2) and O(3) absorption spectra in exoplanetary atmospheres as ideal signatures of biology. However, oxygenic photosynthesis may not arise ubiquitously in exoplanetary biospheres. Alternative evolutionary paths may yield planetary atmospheres tinted with the waste products of other dominant metabolisms, including potentially exotic biochemistries. This paper defines chlorinic photosynthesis (CPS) as biologically mediated photolytic oxidation of aqueous Cl(-) to form halocarbon or dihalogen products, coupled with CO(2) assimilation. This hypothetical metabolism appears to be feasible energetically, physically, and geochemically, and could potentially develop under conditions that approximate the terrestrial Archean. It is hypothesized that an exoplanetary biosphere in which chlorinic photosynthesis dominates primary production would tend to evolve a strongly oxidizing, halogen-enriched atmosphere over geologic time. It is recommended that astronomical observations of exoplanetary outgoing thermal emission spectra consider signs of halogenated chemical species as likely indicators of the presence of a chlorinic biosphere. Planets that favor the evolution of CPS would probably receive equivalent or greater surface UV flux than is produced by the Sun, which would promote stronger abiotic UV photolysis of aqueous halides than occurred during Earth's Archean era and impose stronger evolutionary selection pressures on endemic life to accommodate and utilize halogenated compounds. Ocean-bearing planets of stars with metallicities equivalent to, or greater than, the Sun should especially favor the evolution of chlorinic biospheres because of the higher relative seawater abundances of Cl, Br, and I such planets would tend to host. Directed searches for chlorinic biospheres should probably focus on G0-G2, F, and A spectral class stars that have bulk metallicities of +0.0 Dex or greater.

Effects of light and temperature on duckweed photosynthesis

Energy Technology Data Exchange (ETDEWEB)

Wedge, R M; Burris, J E

1982-06-01

Rates of photosynthesis of Lemna minor L. and Spirodela punctata, two aquatic angiosperms, were measured at different temperatures and light intensities. Photosynthesis was measured both as oxygen evolution and /sup 14/CO/sub 2/ fixation. At temperatures ranging from 15 to 35/sup 0/C, light saturation of photosynthetic O/sub 2/ evolution of Lemna occured from 300-600 ..mu..E m/sup -2/ s/sup -1/, while in Spirodela photosynthetic O/sub 2/ evolution was light saturated at 5600-1200 ..mu..E m/sup -2/ s/sup -1/. Photosynthetic O/sub 2/ evolution of both species was photoinhibited at light intensities greater than 1200 ..mu..E m/sup -2/ s/sup -1/. The optimal temperature for Lemna photosynthetic O/sub 2/ evolution was 30/sup 0/C, while the optimal temperatures for /sup 14/CO/sub 2/ fixation were from 20 to 30/sup 0/C. For Spirodela maximum photosynthetic O/sub 2/, evolution occurred at 35/sup 0/C, while maximum /sup 14/CO/sub 2/ fixation was at 30/sup 0/C.

Biocatalytic photosynthesis with water as an electron donor.

Science.gov (United States)

Ryu, Jungki; Nam, Dong Heon; Lee, Sahng Ha; Park, Chan Beum

2014-09-15

Efficient harvesting of unlimited solar energy and its conversion into valuable chemicals is one of the ultimate goals of scientists. With the ever-increasing concerns about sustainable growth and environmental issues, numerous efforts have been made to develop artificial photosynthetic process for the production of fuels and fine chemicals, thus mimicking natural photosynthesis. Despite the research progress made over the decades, the technology is still in its infancy because of the difficulties in kinetic coupling of whole photocatalytic cycles. Herein, we report a new type of artificial photosynthesis system that can avoid such problems by integrally coupling biocatalytic redox reactions with photocatalytic water splitting. We found that photocatalytic water splitting can be efficiently coupled with biocatalytic redox reactions by using tetracobalt polyoxometalate and Rh-based organometallic compound as hole and electron scavengers, respectively, for photoexcited [Ru(bpy)3](2+). Based on these results, we could successfully photosynthesize a model chiral compound (L-glutamate) using a model redox enzyme (glutamate dehydrogenase) upon in situ photoregeneration of cofactors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reevaluation of the plant "gemstones": Calcium oxalate crystals sustain photosynthesis under drought conditions.

Science.gov (United States)

Tooulakou, Georgia; Giannopoulos, Andreas; Nikolopoulos, Dimosthenis; Bresta, Panagiota; Dotsika, Elissavet; Orkoula, Malvina G; Kontoyannis, Christos G; Fasseas, Costas; Liakopoulos, Georgios; Klapa, Maria I; Karabourniotis, George

2016-09-01

Land plants face the perpetual dilemma of using atmospheric carbon dioxide for photosynthesis and losing water vapors, or saving water and reducing photosynthesis and thus growth. The reason behind this dilemma is that this simultaneous exchange of gases is accomplished through the same minute pores on leaf surfaces, called stomata. In a recent study we provided evidence that pigweed, an aggressive weed, attenuates this problem exploiting large crystals of calcium oxalate as dynamic carbon pools. This plant is able to photosynthesize even under drought conditions, when stomata are closed and water losses are limited, using carbon dioxide from crystal decomposition instead from the atmosphere. Abscisic acid, an alarm signal that causes stomatal closure seems to be implicated in this function and for this reason we named this path "alarm photosynthesis." The so-far "enigmatic," but highly conserved and widespread among plant species calcium oxalate crystals seem to play a crucial role in the survival of plants.

Growth, water relations and photosynthesis of seedlings and resprouts after fire

Science.gov (United States)

Clemente, Adelaide S.; Rego, Francisco C.; Correia, Otília A.

2005-05-01

Seasonal patterns of growth, water relations, photosynthesis and leaf characteristics were compared between obligate seeders ( Cistus monspeliensis and Cistus ladanifer) and resprouters ( Arbutus unedo and Pistacia lentiscus) from the first to the second year after fire. We hypothesized that seedlings would be more water-limited than resprouts due to their shallower root systems. Regarding water use strategies, Cistus species are drought semi-deciduous and A. unedo and P. lentiscus are evergreen sclerophylls, therefore, comparisons were based on the relative deviation from mature conspecific plants. Seedlings and resprouts had higher shoot elongation and leaf production than mature plants, and over an extended period. Differences from mature plants were larger in resprouts, with two-fold transpiration, leaf conductance and photosynthesis in late spring/early summer. Seedlings of C. monspeliensis exhibited higher transpiration and leaf conductance than mature plants, while those of C. ladanifer only exhibited higher water potential. Growth increments and ameliorated water relations and photosynthesis after fire were attributed to an increase in water and nutrient availability. The small differences in water relations and photosynthesis between seedlings and mature conspecifics are in accordance with the prediction of seedlings experiencing higher water limitation than resprouts. We attribute these results to differences in root systems: resprouters benefited from an increase in root/shoot ratios and the presence of deep roots whereas Cistus seedlings relied on very shallow roots, which cannot provide assess to deep water during summer. Nevertheless, seedlings did not show evidence of experiencing a more severe water limitation than mature conspecifics, which we attributed to the presence of efficient mechanisms of avoiding and tolerating water stress. The results are discussed in relation to post-fire demography of seeders and resprouters in Mediterranean

Relative Sensitivity of Photosynthesis and Respiration to Freeze-Thaw Stress in Herbaceous Species 1

Science.gov (United States)

Steffen, Kenneth L.; Arora, Rajeev; Palta, Jiwan P.

1989-01-01

The relative effect of a freeze-thaw cycle on photosynthesis, respiration, and ion leakage of potato leaf tissue was examined in two potato species, Solanum acaule Bitt. and Solanum commersonii Dun. Photosynthesis was found to be much more sensitive to freezing stress than was respiration, and demonstrated more than a 60% inhibition before any impairment of respiratory function was observed. Photosynthesis showed a slight to moderate inhibition when only 5 to 10% of the total electrolytes had leaked from the tissue (reversible injury). This was in contrast to respiration which showed no impairment until temperatures at which about 50% ion leakage (irreversible injury) had occurred. The influence of freeze-thaw protocol was further examined in S. acaule and S. commersonii, in order to explore discrepancies in the literature as to the relative sensitivities of photosynthesis and respiration. As bath cooling rates increased from 1°C/hour to about 3 or 6°C/hour, there was a dramatic increase in the level of damage to all measured cellular functions. The initiation of ice formation in deeply supercooled tissue caused even greater damage. As the cooling rates used in stress treatments increased, the differential sensitivity between photosynthesis and respiration nearly disappeared. Examination of agriculturally relevant, climatological data from an 11 year period confirmed that air cooling rates in the freezing range do not exceed 2°C/hour. It was demonstrated, in the studies presented here, that simply increasing the actual cooling rate from 1.0 to 2.9°C/hour, in frozen tissue from paired leaflet halves, meant the difference between cell survival and cell death. Images Figure 4 Figure 5 PMID:16666712

Photosynthesis and Ribulose 1,5-Bisphosphate Concentrations in Intact Leaves of Xanthium strumarium L.

Science.gov (United States)

Mott, K A; Jensen, R G; O'leary, J W; Berry, J A

1984-12-01

The interacting effects of the rate of ribulose 1,5-bisphosphate (RuBP) regeneration and the rate of RuBP utilization as influenced by the amount and activation of RuBP carboxylase on photosynthesis and RuBP concentrations were resolved in experiments which examined the kinetics of the response of photosynthesis and RuBP concentrations after step changes from a rate-saturating to a rate-limiting light intensity in Xanthium strumarium. Because RuBP carboxylase requires several minutes to deactivate in vivo, it was possible to observe the effect of reducing the rate of RuBP regeneration on the RuBP concentration at constant enzyme activation state by sampling very soon after reducing the light intensity. Samples taken over longer time periods showed the effect of changes in enzyme activation at constant RuBP regeneration rate on RuBP concentration and photosynthetic rate. Within 15 s of lowering the light intensity from 1500 to 600 microEinsteins per square meter per second the RuBP concentration in the leaves dropped below the enzyme active site concentration, indicating that RuBP regeneration rate was limiting for photosynthesis. After longer intervals of time, the RuBP concentration in the leaf increased as the RuBP carboxylase assumed a new steady state activation level. No change in the rate of photosynthesis was observed during the interval that RuBP concentration increased. It is concluded that the rate of photosynthesis at the lower light intensity was limited by the rate of RuBP regeneration and that parallel changes in the activation of RuBP carboxylase occurred such that concentrations of RuBP at steady state were not altered by changes in light intensity.

Technical oversight for installation of TNX piezometers, Final Report

Energy Technology Data Exchange (ETDEWEB)

Pidcoe, W.W. Jr. [Westinghouse Savannah River Company, Aiken, SC (United States)

1997-06-05

Science Applications International Corporation was tasked under subcontract C002025P to provide technical oversight for the drilling of one pilot borehole, and the drilling and installation of five piezometers in the TNX Area Swamp. The work was performed in accordance with the Statement of Work in Task Order Proposal No. ER39-129 dated August 6, 1996. This report describes the activities associated with the performance of the task.

Artificial photosynthesis: from basic biology to industrial application

National Research Council Canada - National Science Library

Collings, Anthony F; Critchley, Christa

2005-01-01

... some of the same outcomes at rates and scales that far exceed those found in nature. In this field the ubiquitous process is photosynthesis - an ancient process inherent to almost all plants and many prokaryotes on the planet that ultimately enabled the development of earth's animal kingdom. From a practical perspective, the natural process of photosynth...

Differential effects of glyphosate and aminomethylphosphonic acid (AMPA) on photosynthesis and chlorophyll metabolism in willow plants.

Science.gov (United States)

Gomes, Marcelo Pedrosa; Le Manac'h, Sarah Gingras; Maccario, Sophie; Labrecque, Michel; Lucotte, Marc; Juneau, Philippe

2016-06-01

We used a willow species (Salix miyabeana cultivar SX64) to examine the differential secondary-effects of glyphosate and aminomethylphosphonic acid (AMPA), the principal glyphosate by-product, on chlorophyll metabolism and photosynthesis. Willow plants were treated with different concentrations of glyphosate (equivalent to 0, 1.4, 2.1 and 2.8kgha(-1)) and AMPA (equivalent to 0, 0.28, 1.4 and 2.8kgha(-1)) and evaluations of pigment contents, chlorophyll fluorescence, and oxidative stress markers (hydrogen peroxide content and antioxidant enzyme activities) in leaves were performed after 12h of exposure. We observed that AMPA and glyphosate trigger different mechanisms leading to decreases in chlorophyll content and photosynthesis rates in willow plants. Both chemicals induced ROS accumulation in willow leaves although only glyphosate-induced oxidative damage through lipid peroxidation. By disturbing chlorophyll biosynthesis, AMPA induced decreases in chlorophyll contents, with consequent effects on photosynthesis. With glyphosate, ROS increases were higher than the ROS-sensitive threshold, provoking chlorophyll degradation (as seen by pheophytin accumulation) and invariable decreases in photosynthesis. Peroxide accumulation in both AMPA and glyphosate-treated plants was due to the inhibition of antioxidant enzyme activities. The different effects of glyphosate on chlorophyll contents and photosynthesis as described in the literature may be due to various glyphosate:AMPA ratios in those plants. Copyright © 2015 Elsevier Inc. All rights reserved.

A two-dimensional microscale model of gas exchange during photosynthesis in maize (Zea mays L.) leaves.

Science.gov (United States)

Retta, Moges; Ho, Quang Tri; Yin, Xinyou; Verboven, Pieter; Berghuijs, Herman N C; Struik, Paul C; Nicolaï, Bart M

2016-05-01

CO2 exchange in leaves of maize (Zea mays L.) was examined using a microscale model of combined gas diffusion and C4 photosynthesis kinetics at the leaf tissue level. Based on a generalized scheme of photosynthesis in NADP-malic enzyme type C4 plants, the model accounted for CO2 diffusion in a leaf tissue, CO2 hydration and assimilation in mesophyll cells, CO2 release from decarboxylation of C4 acids, CO2 fixation in bundle sheath cells and CO2 retro-diffusion from bundle sheath cells. The transport equations were solved over a realistic 2-D geometry of the Kranz anatomy obtained from light microscopy images. The predicted responses of photosynthesis rate to changes in ambient CO2 and irradiance compared well with those obtained from gas exchange measurements. A sensitivity analysis showed that the CO2 permeability of the mesophyll-bundle sheath and airspace-mesophyll interfaces strongly affected the rate of photosynthesis and bundle sheath conductance. Carbonic anhydrase influenced the rate of photosynthesis, especially at low intercellular CO2 levels. In addition, the suberin layer at the exposed surface of the bundle sheath cells was found beneficial in reducing the retro-diffusion. The model may serve as a tool to investigate CO2 diffusion further in relation to the Kranz anatomy in C4 plants. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Volatiles combustion in fluidized beds. Final technical report, 4 September 1992--4 June 1995

Energy Technology Data Exchange (ETDEWEB)

Pendergrass, R.A. II; Raffensperger, C.; Hesketh, R.P.

1996-02-29

The goal of this project is to investigate the conditions in which volatiles will burn within both the dense and freeboard regions of fluidized beds. Experiments using a fluidized bed operated at incipient fluidization are being conducted to characterize the effect of particle surface area, initial fuel concentration, and particle type on the inhibition of volatiles within a fluidized bed. A review of the work conducted under this grant is presented in this Final Technical Report. Both experimental and theoretical work have been conducted to examine the inhibition of the combustion by the fluidized bed material, sand. It has been shown that particulate phase at incipient fluidization inhibits the combustion of propane by free radical destruction at the surface of sand particles within the particulate phase. The implications of these findings is that at bed temperatures lower than the critical temperatures, gas combustion can only occur in the bubble phase or at the top surface of a bubbling fluidized bed. In modeling fluidized bed combustion this inhibition by the particulate phase should be included.

Photosynthesis-fermentation hybrid system to produce lipid feedstock for algal biofuel.

Science.gov (United States)

Lu, Yue; Dai, Junbiao; Wu, Qingyu

2013-01-01

To avoid bacterial contamination due to medium replacement in the expanded application of a photosynthesis-fermentation model, an integrated photosynthesis-fermentation hybrid system was set up and evaluated for algal lipid production using Chlorella protothecoides. In this system, the CO2-rich off-gas from the fermentation process was recycled to agitate medium in thephotobioreactor, which could provide initial cells for the heterotrophic fermentation. The cell concentration reached 1.03 +/- 0.07 g/L during photoautotrophic growth and then the concentrated green cells were switched to heterotrophic fermentation after removing over 99.5% ofnitrogen in the medium by a nitrogen removal device. At the end offermentation in the system, the cell concentration could reach as high as 100.51 +/- 2.03 g/L, and 60.05 +/- 1.38% lipid content was achieved simultaneously. The lipid yield (60.36 +/- 2.63 g/L) in the hybrid system was over 700 times higher than that in a photobioreactor and exceeded that by fermentation alone (47.56 +/- 7.31 g/L). The developed photosynthesis-fermentation hybrid system in this study was not only a feasible option to enhance microalgal lipid production, but also an environment-friendly approach to produce biofuel feedstock through concurrent utilization of ammonia nitrogen, CO2, and organic carbons.

Effects of enhances ultra violet irradiation on photosynthesis in ...

African Journals Online (AJOL)

Effects of enhances ultra violet irradiation on photosynthesis in anabaena variabilis and phormidium uncinatum. VA Donkor. Abstract. No Abstract. Journal of the Ghana Association Vol. 2 (3) 1999: pp.16-23. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT.

Enhanced Thermostability of Arabidopsis Rubisco activase improves photosynthesis and growth rates under moderate heat stress.

Science.gov (United States)

Kurek, Itzhak; Chang, Thom Kai; Bertain, Sean M; Madrigal, Alfredo; Liu, Lu; Lassner, Michael W; Zhu, Genhai

2007-10-01

Plant photosynthesis declines when the temperature exceeds its optimum range. Recent evidence indicates that the reduction in photosynthesis is linked to ribulose-1,5-bis-phosphate carboxylase/oxygenase (Rubisco) deactivation due to the inhibition of Rubisco activase (RCA) under moderately elevated temperatures. To test the hypothesis that thermostable RCA can improve photosynthesis under elevated temperatures, we used gene shuffling technology to generate several Arabidopsis thaliana RCA1 (short isoform) variants exhibiting improved thermostability. Wild-type RCA1 and selected thermostable RCA1 variants were introduced into an Arabidopsis RCA deletion (Deltarca) line. In a long-term growth test at either constant 26 degrees C or daily 4-h 30 degrees C exposure, the transgenic lines with the thermostable RCA1 variants exhibited higher photosynthetic rates, improved development patterns, higher biomass, and increased seed yields compared with the lines expressing wild-type RCA1 and a slight improvement compared with untransformed Arabidopsis plants. These results provide clear evidence that RCA is a major limiting factor in plant photosynthesis under moderately elevated temperatures and a potential target for genetic manipulation to improve crop plants productivity under heat stress conditions.

Development of the biosphere code BIOMOD: final report

International Nuclear Information System (INIS)

Kane, P.

1983-05-01

Final report to DoE on the development of the biosphere code BIOMOD. The work carried out under the contract is itemised. Reference is made to the six documents issued along with the final report. These consist of two technical notes issued as interim consultative documents, a user's guide and a programmer's guide to BIOMOD, a database description, program test document and a technical note entitled ''BIOMOD - preliminary findings''. (author)

A Detector for Combined SPECT/CT. Final Technical Report

International Nuclear Information System (INIS)

Vivek Nagarkar

2006-01-01

The goal of the Phase I research was to demonstrate the feasibility of developing a high performance SPECT/CT detector module based on a combination of microcolumnar CsI(Tl) scintillator coupled to an EMCCD readout. We are very pleased to report that our Phase I research has demonstrated the technical feasibility of our approach with a very high degree of success. Specifically, we were able to implement a back-thinned EMCCD with a fiberoptic window which was successfully used to demonstrate the feasibility of near simultaneous radionuclide/CT using the proposed concept. Although significantly limited in imaging area (24 x 24 mm 2 ) and pixel resolution (512 x 512), this prototype has shown exceptional capabilities such as a single optical photon sensitivity, very low noise, an intrinsic resolution of 64 (micro)m for radionuclide imaging, and a resolution in excess of 10 lp/mm for x-ray imaging. Furthermore, the combination of newly developed, thick, microcolumnar CsI and an EMCCD has shown to be capable of operating in a photon counting mode, and that the position and energy information obtained from these data can be used to improve resolution in radionuclide imaging. Finally, the prototype system has successfully been employed for near simultaneous SPECT/CT imaging using both, 125 I and 99m Tc radioisotopes. The tomographic reconstruction data obtained using a mouse heart phantom and other phantoms clearly demonstrate the feasibility and efficacy of the detector in small animal research. The following were the objectives specified in the Phase I proposal: (1) In consultation with Professor Hasegawa, develop specifications for the Phase I/Phase II prototype detector; (2) Modify current vapor deposition protocols to fabricate ∼2 mm thick microcolumnar CsI(Tl) scintillators with excellent columnar structure, high light yield, and high spatial resolution; (3) Perform detailed characterization of the film morphology, light output, and spatial resolution, and use

Final Technical Report: "Representing Endogenous Technological Change in Climate Policy Models: General Equilibrium Approaches"

Energy Technology Data Exchange (ETDEWEB)

Ian Sue Wing

2006-04-18

The research supported by this award pursued three lines of inquiry: (1) The construction of dynamic general equilibrium models to simulate the accumulation and substitution of knowledge, which has resulted in the preparation and submission of several papers: (a) A submitted pedagogic paper which clarifies the structure and operation of computable general equilibrium (CGE) models (C.2), and a review article in press which develops a taxonomy for understanding the representation of technical change in economic and engineering models for climate policy analysis (B.3). (b) A paper which models knowledge directly as a homogeneous factor, and demonstrates that inter-sectoral reallocation of knowledge is the key margin of adjustment which enables induced technical change to lower the costs of climate policy (C.1). (c) An empirical paper which estimates the contribution of embodied knowledge to aggregate energy intensity in the U.S. (C.3), followed by a companion article which embeds these results within a CGE model to understand the degree to which autonomous energy efficiency improvement (AEEI) is attributable to technical change as opposed to sub-sectoral shifts in industrial composition (C.4) (d) Finally, ongoing theoretical work to characterize the precursors and implications of the response of innovation to emission limits (E.2). (2) Data development and simulation modeling to understand how the characteristics of discrete energy supply technologies determine their succession in response to emission limits when they are embedded within a general equilibrium framework. This work has produced two peer-reviewed articles which are currently in press (B.1 and B.2). (3) Empirical investigation of trade as an avenue for the transmission of technological change to developing countries, and its implications for leakage, which has resulted in an econometric study which is being revised for submission to a journal (E.1). As work commenced on this topic, the U.S. withdrawal

Photosynthesis-dependent isoprene emission from leaf to planet in a global carbon-chemistry-climate model

OpenAIRE

Unger, N.; Harper, K.; Zheng, Y.; Kiang, N. Y.; Aleinov, I.; Arneth, A.; Schurgers, G.; Amelynyck, C.; Goldstein, A.; Guenther, A.; Heinesch, B.; Hewitt, C. N.; Karl, T.; Laffineur, Q.; Langford, B.

2013-01-01

We describe the implementation of a biochemical model of isoprene emission that depends on the electron requirement for isoprene synthesis into the Farquhar–Ball–Berry leaf model of photosynthesis and stomatal conductance that is embedded within a global chemistry-climate simulation framework. The isoprene production is calculated as a function of electron transport-limited photosynthesis, intercellular and atmospheric carbon dioxide concentration, and canopy temperature. Th...

A two-dimensional microscale model of gas exchange during photosynthesis in maize (Zea mays L.) leaves

NARCIS (Netherlands)

Retta, Moges; Ho, Quang Tri; Yin, Xinyou; Verboven, Pieter; Berghuijs, Herman N.C.; Struik, Paul C.; Nicolaï, Bart M.

2016-01-01

CO₂ exchange in leaves of maize (Zea mays L.) was examined using a microscale model of combined gas diffusion and C₄ photosynthesis kinetics at the leaf tissue level. Based on a generalized scheme of photosynthesis in NADP-malic enzyme type C₄ plants, the model

Modelling soil temperature and moisture and corresponding seasonality of photosynthesis and transpiration in a boreal spruce ecosystem

Science.gov (United States)

Wu, S. H.; Jansson, P.-E.

2013-02-01

Recovery of photosynthesis and transpiration is strongly restricted by low temperatures in air and/or soil during the transition period from winter to spring in boreal zones. The extent to which air temperature (Ta) and soil temperature (Ts) influence the seasonality of photosynthesis and transpiration of a boreal spruce ecosystem was investigated using a process-based ecosystem model (CoupModel) together with eddy covariance (EC) data from one eddy flux tower and nearby soil measurements at Knottåsen, Sweden. A Monte Carlo-based uncertainty method (GLUE) provided prior and posterior distributions of simulations representing a wide range of soil conditions and performance indicators. The simulated results showed sufficient flexibility to predict the measured cold and warm Ts in the moist and dry plots around the eddy flux tower. Moreover, the model presented a general ability to describe both biotic and abiotic processes for the Norway spruce stand. The dynamics of sensible heat fluxes were well described by the corresponding latent heat fluxes and net ecosystem exchange of CO2. The parameter ranges obtained are probably valid to represent regional characteristics of boreal conifer forests, but were not easy to constrain to a smaller range than that produced by the assumed prior distributions. Finally, neglecting the soil temperature response function resulted in fewer behavioural models and probably more compensatory errors in other response functions for regulating the seasonality of ecosystem fluxes.

Crown structure, radiation absorption, photosynthesis and transpiration

OpenAIRE

Wang, Yingping

1988-01-01

A complex simulation model, MAESTRO, has been developed and validated against field measurements in plantation in both Scotland and Australia. It has been shown that MAESTRO can reasonably predict the daily course of PAR (photosynetically active radiation) transmittance at points below the canopies of radiata pine and Sitka spruce plantations. 1. Four structural properties of the Sitka spruce tree crown have been identified and evaluation in relation to PAR absorption, photosynthesis and ...

In situ autumn ozone fumigation of mature Norway spruce - Effects on net photosynthesis

DEFF Research Database (Denmark)

Mikkelsen, Teis Nørgaard; Ro-Poulsen, H.

2002-01-01

concentration. The experiment was conducted during 70 days during the autumn. Our system could not detect any ozone effects on dark respiration, but eventually effects on dark respiration could be masked in signal noise. An inhibition of daily net photosynthesis in ozone treated shoots was apparent......, and it is was found that a mean increase in ozone concentration of 10 nl l(-1) reduced net photosynthesis with 7.4 %. This effect should be related to a pre-exposure during the season of AOT40 12.5 mul l(-1) h....

Tracking diurnal changes of photosynthesis and evapotranspiration using fluorescence, gas exchange and hyperspectral remote sensing measurements

Science.gov (United States)

Wang, S.; Zhang, L.; Guanter, L.; Huang, C.

2017-12-01

Photosynthesis and evapotranspiration (ET) are the two most important activities of vegetation and make a great contribution to carbon, water and energy exchanges. Remote sensing provides opportunities for monitoring these processes across time and space. This study focuses on tracking diurnal changes of photosynthesis and evapotranspiration over soybean using multiple measurement techniques. Diurnal changes of both remote sensing-based indicators, including active and passive chlorophyll fluorescence and biophysical-related parameters, including photosynthesis rate (photo) and leaf stomatal conductance (cond), were observed. Results showed that both leaf-level steady-state fluorescence (Fs) and canopy-level solar-induced chlorophyll fluorescence were linearly correlated to photosynthetically active radiation (PAR) during the daytime. A double-peak diurnal change curve was observed for leaf-level photo and cond but not for Fs or SIF. Photo and cond showed a strong nonlinear (second-order) correlation, indicating that photosynthesis, which might be remotely sensed by SIF, has the opportunity to track short-term changes of ET. Results presented in this report will be helpful for better understanding the relationship between remote-sensing-based indices and vegetation's biophysical processes.

UV-B sensitivity of plant photosynthesis as influenced by visible irradiation

International Nuclear Information System (INIS)

Caldwell, M.M.; Warner, C.W.

1982-01-01

Experiments were made to separate the effects of preconditioning and concomitant visible irradiation and to investigate this with respect to both light-limited and light-saturated photosynthesis. (orig./AJ)

Virginia Solar Pathways Project Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Bond, Katharine; Cosby, Sarah

2018-03-28

This Report provides a technical review of the final results of a funding award to Virginia Electric and Power Company (Dominion Energy Virginia (DEV) or the Company) for a project under the U.S. Department of Energy’s Solar Energy Technologies Office. The three-year project was formally known as the Virginia Solar Pathways Project (VSPP or the Project). The purpose of the VSPP was to develop a collaborative utility-administered solar strategy (Solar Strategy) for DEV’s service territory in the Commonwealth that could serve as a replicable model for other states with similar policy environments. The U.S. Department of Energy (DOE) funding award enabled DEV to take a focused approach to developing the Solar Strategy for its Virginia service territory. The structure and funding from the DOE award also facilitated valuable input from a formal stakeholder team convened to serve as advisors (Advisory Team) to the VSPP and contribute their perspectives and expertise to both the analysis and strategy development aspects of the Project. The development of the Solar Strategy involved three main goals: • Establish a policy and program framework that would integrate existing solar programs with new options appropriate for the Commonwealth’s policy environment and broader economic development objectives; • Promote wider deployment of solar within a low retail electric rate environment; and • Serve as a sustainable, utility-administered solar model that could be replicated in other states with similar policy environments, including, but not limited to, the entire Southeast region. In support of the VSPP goals, the Project Team commissioned four studies to support the Solar Strategy development. Two studies, completed by Navigant Consulting, focused on the integration of solar into the electric grid. The first solar integration study focused on integration of solar into the distribution grid where the utility system directly connects to and serves end-use customers

FOREX trading strategy formation using technical analysis

OpenAIRE

Klimavičius, Domas

2010-01-01

FOREX technical analysis indicators, their characteristics and capabilities are researched in this final master thesis. The main goal of this thesis is to determine if technical analysis indicators can recognise patterns in price movements and if they can predict future price movement. The first part of the thesis presents with FOREX theoretical aspects, its characteristics and participants. In the second part of the thesis FOREX analysis tools are overviewed, focusing on technical analysis. ...

Pectin Methylesterification Impacts the Relationship between Photosynthesis and Plant Growth1[OPEN

Science.gov (United States)

Kim, Sang-Jin; Renna, Luciana; Brandizzi, Federica

2016-01-01

Photosynthesis occurs in mesophyll cells of specialized organs such as leaves. The rigid cell wall encapsulating photosynthetic cells controls the expansion and distribution of cells within photosynthetic tissues. The relationship between photosynthesis and plant growth is affected by leaf area. However, the underlying genetic mechanisms affecting carbon partitioning to different aspects of leaf growth are not known. To fill this gap, we analyzed Arabidopsis plants with altered levels of pectin methylesterification, which is known to modulate cell wall plasticity and plant growth. Pectin methylesterification levels were varied through manipulation of cotton Golgi-related (CGR) 2 or 3 genes encoding two functionally redundant pectin methyltransferases. Increased levels of methylesterification in a line over-expressing CGR2 (CGR2OX) resulted in highly expanded leaves with enhanced intercellular air spaces; reduced methylesterification in a mutant lacking both CGR-genes 2 and 3 (cgr2/3) resulted in thin but dense leaf mesophyll that limited CO2 diffusion to chloroplasts. Leaf, root, and plant dry weight were enhanced in CGR2OX but decreased in cgr2/3. Differences in growth between wild type and the CGR-mutants can be explained by carbon partitioning but not by variations in area-based photosynthesis. Therefore, photosynthesis drives growth through alterations in carbon partitioning to new leaf area growth and leaf mass per unit leaf area; however, CGR-mediated pectin methylesterification acts as a primary factor in this relationship through modulation of the expansion and positioning of the cells in leaves, which in turn drive carbon partitioning by generating dynamic carbon demands in leaf area growth and leaf mass per unit leaf area. PMID:27208234

Changes in photosynthesis and activities of enzymes involved in ...

African Journals Online (AJOL)

AJL

2012-04-26

Apr 26, 2012 ... oxygen and carbohydrates. In photosynthesis, a series of redox reactions occur in the electron transport system present in the chloroplast thylakoid membranes. Oxi- dation of water is catalyzed by photosystem II (PSII), a multi-subunit pigment protein complex located in the thylakoid membrane (Hillier and ...

Effects of proline on photosynthesis, root reactive oxygen species ...

African Journals Online (AJOL)

use

2011-12-14

Dec 14, 2011 ... Hoagland's nutrient solution (pH 6.3 to 6.5, EC 2.0 to 2.2 dS m-1). The nutrient .... photosynthesis system (LI-6400, LI-COR, Lincoln, NE, USA). The ..... Duan JJ, Li J, Guo SR, Kang YY (2008). ... Foster JG, Hess JL (1980).

Limited effect of ozone reductions on the 20-year photosynthesis trend at Harvard forest.

Science.gov (United States)

Yue, Xu; Keenan, Trevor F; Munger, William; Unger, Nadine

2016-11-01

Ozone (O 3 ) damage to leaves can reduce plant photosynthesis, which suggests that declines in ambient O 3 concentrations ([O 3 ]) in the United States may have helped increase gross primary production (GPP) in recent decades. Here, we assess the effect of long-term changes in ambient [O 3 ] using 20 years of observations at Harvard forest. Using artificial neural networks, we found that the effect of the inclusion of [O 3 ] as a predictor was slight, and independent of O 3 concentrations, which suggests limited high-frequency O 3 inhibition of GPP at this site. Simulations with a terrestrial biosphere model, however, suggest an average long-term O 3 inhibition of 10.4% for 1992-2011. A decline of [O 3 ] over the measurement period resulted in moderate predicted GPP trends of 0.02-0.04 μmol C m -2  s -1  yr -1 , which is negligible relative to the total observed GPP trend of 0.41 μmol C m -2  s -1  yr -1 . A similar conclusion is achieved with the widely used AOT40 metric. Combined, our results suggest that ozone reductions at Harvard forest are unlikely to have had a large impact on the photosynthesis trend over the past 20 years. Such limited effects are mainly related to the slow responses of photosynthesis to changes in [O 3 ]. Furthermore, we estimate that 40% of photosynthesis happens in the shade, where stomatal conductance and thus [O 3 ] deposition is lower than for sunlit leaves. This portion of GPP remains unaffected by [O 3 ], thus helping to buffer the changes of total photosynthesis due to varied [O 3 ]. Our analyses suggest that current ozone reductions, although significant, cannot substantially alleviate the damages to forest ecosystems. © 2016 John Wiley & Sons Ltd.

Toxic effects of chlorinated organic compounds and potassium dichromate on growth rate and photosynthesis of marine phytoplankton

DEFF Research Database (Denmark)

Kusk, Kresten Ole; Nyholm, Niels

1992-01-01

The toxic effects of potassium dichromate (K2Cr2O7), 3,4-dichloroaniline (DCA) and 2,4-dichlorophenol (DCP) on the photosynthesis of natural marine phytoplankton and five species of marine microalgae were investigated. Effect concentrations corresponding to a 50 % depression of photosynthesis (6h...

Changes in leaf area, nitrogen content and canopy photosynthesis in soybean exposed to an ozone concentration gradient

Science.gov (United States)

Influences of ozone (O3) on light-saturated rates of photosynthesis in crop leaves have been well documented. To increase our understanding of O3 effects on individual- or stand level productivity, a mechanistic understanding of factors determining canopy photosynthesis is necessary. We used a canop...

Effects of ultraviolet light on photosynthesis and pigments of Antarctic marine phytoplankton

International Nuclear Information System (INIS)

Stephens, F.C.

1989-01-01

This field study was conducted at Palmer Station, Anvers Island, Antarctica, during November-December, 1987. The main objectives were to quantify the effects on photosynthetic rates and pigmentation of short-term and long-term exposures of Antarctic phytoplankton to different levels of UV radiation. Phytoplankton and ice algae were exposed to four levels of UV radiation in outdoor incubation chambers: near ambient UV; UV enhanced by approximately 5% over ambient levels; reduced UV-B; and essentially no UV. Results of 4-hour studies showed that rates of phytoplankton photosynthesis were generally inversely related to UV exposure. Higher photosynthetic rates were maintained over a greater range of irradiance levels when UV was removed in photosynthesis-irradiance studies. Photosynthetic pigments did not change with variations in either visible or UV light. After adaptation for 24 hours, photosynthetic rate measured under conditions of essentially no UV was approximately twice that measured under near ambient UV conditions. Results of photosynthesis-irradiance experiments indicate that photosynthetic efficiencies (α), maximum photosynthetic rates (P max ) and the index of inhibition (I b ) were inversely related to UV levels, probably due at least in part to the loss of chlorophyll a

Impact of the ion transportome of chloroplasts on the optimization of photosynthesis.

Science.gov (United States)

Szabò, Ildikò; Spetea, Cornelia

2017-06-01

Ions play fundamental roles in all living cells, and their gradients are often essential to fuel transport, regulate enzyme activities, and transduce energy within cells. Regulation of their homeostasis is essential for cell metabolism. Recent results indicate that modulation of ion fluxes might also represent a useful strategy to regulate one of the most important physiological processes taking place in chloroplasts, photosynthesis. Photosynthesis is highly regulated, due to its unique role as a cellular engine for growth in the light. Controlling the balance between ATP and NADPH synthesis is a critical task, and availability of these molecules can limit the overall photosynthetic yield. Photosynthetic organisms optimize photosynthesis in low light, where excitation energy limits CO2 fixation, and minimize photo-oxidative damage in high light by dissipating excess photons. Despite extensive studies of these phenomena, the mechanism governing light utilization in plants is still poorly understood. In this review, we provide an update of the recently identified chloroplast-located ion channels and transporters whose function impacts photosynthetic efficiency in plants. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Inorganic Carbon Source for Photosynthesis in the Seagrass Thalassia hemprichii (Ehrenb.) Aschers.

Science.gov (United States)

Abel, K M

1984-11-01

Photosynthetic carbon uptake of the tropical seagrass Thalassia hemprichii (Ehrenb.) Aschers was studied by several methods. Photosynthesis in buffered seawater in media in the range of pH 6 to pH 9 showed an exponentially increasing rate with decreasing pH, thus indicating that free CO(2) was a photosynthetic substrate. However, these experiments were unable to determine whether photosynthesis at alkaline pH also contained some component due to HCO(3) (-) uptake. This aspect was further investigated by studying photosynthetic rates in a number of media of varying pH (7.8-8.61) and total inorganic carbon (0.75-13.17 millimolar). In these media, photosynthetic rate was correlated with free CO(2) concentration and was independent of the HCO(3) (-) concentration in the medium. Short time-course experiments were conducted during equilibration of free CO(2) and HCO(3) (-) after injection of (14)C labeled solution at acid or alkaline pH. High initial photosynthetic rates were observed when acidic solutions (largely free CO(2)) were used but not with alkaline solutions. The concentration of free CO(2) was found to be a limiting factor for photosynthesis in this plant.

Regressive Evolution of Photosynthesis in the Roseobacter Clade

Czech Academy of Sciences Publication Activity Database

Koblížek, Michal; Zeng, Yonghui; Horák, A.; Oborník, Miroslav

2013-01-01

Roč. 66, č. 2013 (2013), s. 385-405 ISSN 0065-2296 R&D Projects: GA ČR GAP501/10/0221; GA ČR GBP501/12/G055; GA MŠk ED2.1.00/03.0110 Institutional support: RVO:61388971 Keywords : roseobacter clade * photosynthesis * marine microbial communities Subject RIV: EE - Microbiology, Virology Impact factor: 1.740, year: 2013

Final Technical Report for Year 5 Early Career Research Project "Viscosity and equation of state of hot and dense QCD matter"

Energy Technology Data Exchange (ETDEWEB)

Molnar, Denes [Purdue Univ., West Lafayette, IN (United States)

2016-05-25

The Section below summarizes research activities and achievements during the fifth (last) year of the PI’s Early Career Research Project (ECRP). Unlike the first four years of the project, the last year was not funded under the American Recovery and Reinvestment Act (ARRA). The ECRP advanced two main areas: i) radiative 3 ↔ 2 radiative transport, via development of a new computer code MPC/Grid that solves the Boltzmann transport equation in full 6+1D (3X+3V+time); and ii) application of relativistic hydrodynamics, via development of a self-consistent framework to convert viscous fluids to particles. In Year 5 we finalized thermalization studies with radiative gg ↔ ggg transport (Sec. 1.1.1) and used nonlinear covariant transport to assess the accuracy of fluid-to-particle conversion models (Sec. 1.1.2), calculated observables with self-consistent fluid-to-particle conversion from realistic viscous hydrodynamic evolution (Secs. 1.2.1 and 1.2.2), extended the covariant energy loss formulation to heavy quarks (Sec. 1.4.1) and studied energy loss in small systems (Sec. 1.4.2), and also investigated how much of the elliptic flow could have non-hydrodynamic origin (Sec 1.3). Years 1-4 of the ECRP were ARRA-funded and, therefore, they have their own report document ’Final Technical Report for Years 1-4 of the Early Career Research Project “Viscosity and equation of state of hot and dense QCD matter”’ (same award number DE-SC0004035). The PI’s group was also part of the DOE JET Topical Collaboration, a multi-institution project that overlapped in time significantly with the ECRP. Purdue achievements as part of the JET Top- ical Collaboration are in a separate report “Final Technical Report summarizing Purdue research activities as part of the DOE JET Topical Collaboration” (award DE-SC0004077).

75 FR 33682 - Export Administration Regulations; Technical Amendments

Science.gov (United States)

2010-06-15

...-01] RIN 0694-AE93 Export Administration Regulations; Technical Amendments AGENCY: Bureau of Industry... Bureau of Industry and Security (BIS) makes a technical amendment to the Export Administration... review of final decisions and orders issued in BIS export control administrative enforcement proceedings...

Health care fraud and abuse data collection program: technical revisions to Healthcare Integrity and Protection Data Bank data collection activities. Final rule.

Science.gov (United States)

2004-09-21

The rule finalizes technical changes to the Healthcare Integrity and Protection Data Bank (HIPDB) data collection reporting requirements by clarifying the types of personal numeric identifiers that may be reported to the data bank in connection with adverse actions. The rule clarifies that in lieu of a Social Security Number (SSN), an individual taxpayer identification number (ITIN) may be reported to the data bank when, in those limited situations, an individual does not have an SSN.

Enhancement of photosynthesis in Sorghum bicolor by ultraviolet radiation

International Nuclear Information System (INIS)

Johnson, G.A.; Day, T.A.

2002-01-01

We assessed the influence of ultraviolet radiation (UV) on net photosynthetic CO 2 assimilation rate (Pn) in Sorghum bicolor, with particular attention to examining whether UV can enhance Pn via direct absorption of UV and absorption of UV-induced blue fluorescence by photosynthetic pigments. A polychromatic UV response spectrum of leaves was constructed by measuring Pn under different UV supplements using filters that had sharp transmission cut-offs from 280 to 382 nm, against a background of non-saturating visible light. When the abaxial surface was irradiated, P n averaged 4.6% higher with the UV supplement that cut-off UV at 311 nm, compared to lower and higher UV wavelength supplements. This former supplement differed from higher wavelength supplements by primarily providing more UV between 320 and 350 nm. To assess the possibility of direct absorption of UV by photosynthetic pigments, we measured the absorbance of extracted chlorophylls. Chlorophyll a had absorbance peaks at 340 and 389 nm that were 49 and 72% of that at the sorét peak. Chlorophyll b had absorbance peaks at 315 and 346 nm that were both 35% of that at the sorét peak. Since the epidermis transmits some UV, the strong UV absorbance of chlorophyll implies a potential role for irradiance beyond the bounds of the conventionally defined photosynthetically active radiation waveband (400–700 nm). To assess the role of absorption of UV-induced blue fluorescence, we measured the UV-induced fluorescence excitation and emission spectra of leaves. Abaxial excitation peaked at 328 nm, while emission peaked at 446 nm. In this analysis, we used our abaxial fluorescence excitation spectrum and the UV photosynthetic inhibition spectrum of Caldwell et al. (1986) to weight the UV irradiance with each cut-off filter, thereby estimating the potential contribution of UV-induced blue fluorescence to photosynthesis and the inhibitory effects of UV irradiance on photosynthesis, respectively. With a non

Light dependence of carboxylation capacity for C3 photosynthesis models

Science.gov (United States)

Photosynthesis at high light is often modelled by assuming limitation by the maximum capacity of Rubisco carboxylation at low carbon dioxide concentrations, by electron transport capacity at higher concentrations, and sometimes by triose-phosphate utilization rate at the highest concentrations. Pho...

Enhanced limonene production in cyanobacteria reveals photosynthesis limitations.

Science.gov (United States)

Wang, Xin; Liu, Wei; Xin, Changpeng; Zheng, Yi; Cheng, Yanbing; Sun, Su; Li, Runze; Zhu, Xin-Guang; Dai, Susie Y; Rentzepis, Peter M; Yuan, Joshua S

2016-12-13

Terpenes are the major secondary metabolites produced by plants, and have diverse industrial applications as pharmaceuticals, fragrance, solvents, and biofuels. Cyanobacteria are equipped with efficient carbon fixation mechanism, and are ideal cell factories to produce various fuel and chemical products. Past efforts to produce terpenes in photosynthetic organisms have gained only limited success. Here we engineered the cyanobacterium Synechococcus elongatus PCC 7942 to efficiently produce limonene through modeling guided study. Computational modeling of limonene flux in response to photosynthetic output has revealed the downstream terpene synthase as a key metabolic flux-controlling node in the MEP (2-C-methyl-d-erythritol 4-phosphate) pathway-derived terpene biosynthesis. By enhancing the downstream limonene carbon sink, we achieved over 100-fold increase in limonene productivity, in contrast to the marginal increase achieved through stepwise metabolic engineering. The establishment of a strong limonene flux revealed potential synergy between photosynthate output and terpene biosynthesis, leading to enhanced carbon flux into the MEP pathway. Moreover, we show that enhanced limonene flux would lead to NADPH accumulation, and slow down photosynthesis electron flow. Fine-tuning ATP/NADPH toward terpene biosynthesis could be a key parameter to adapt photosynthesis to support biofuel/bioproduct production in cyanobacteria.

Conceptual change through the use of student-generated analogies of photosynthesis and respiration by college non-science majors

Science.gov (United States)

Hill, Gary D.

Two of the most important and difficult concepts in biology are photosynthesis and respiration. A pilot study was performed using student volunteers from introductory biology classes to assess student alternative frameworks regarding photosynthesis and respiration. The results of the pilot study were used to construct the Instrument for the Assessment of Respiration and Photosynthesis (IFARP). This was an 11-item, three-tier multiple choice instrument designed to conveniently assess the common misconceptions students have about these concepts upon entering a biology course. The first tier of each item of the IFARP contained a multiple choice question about photosynthesis or respiration. The second tier had a multiple choice question regarding the reason for the choice in the first tier. The third tier asked the students to indicate how confident they were in their responses, on a scale from 1 (not very confident) to 5 (very confident). The IFARP was administered as a pretest and posttest to a group of science non-majors in an introductory biology course. No significant changes were observed in student performance as measured by the IFARP between the pretest and posttest administrations. The students did, however, demonstrate a statistical increase in mean confidence levels regarding their knowledge of photosynthesis and respiration. Even though their comprehension and understanding regarding photosynthesis and respiration had not increased, the confidence they had in their responses about these two concepts had increased. The IFARP was also administered to a group of nursing student volunteers in an introductory microbiology course. This group of students also participated in the use of student-generated analogies as a learning strategy to alter conceptual frameworks. One test group of students provided analogies to photosynthesis and respiration, while the other test group provided analogies to two other concepts. No significant changes were observed in the

The evaluation of a framework for measuring the non-technical ward round skills of final year nursing students: An observational study.

Science.gov (United States)

Murray, Kara; McKenzie, Karen; Kelleher, Michael

2016-10-01

The importance of non-technical skills (NTS) to patient outcomes is increasingly being recognised, however, there is limited research into how such skills can be taught and evaluated in student nurses in relation toward rounds. This pilot study describes an evaluation of a NTS framework that could potentially be used to measure ward round skills of student nurses. The study used an observational design. Potential key NTS were identified from existing literature and NTS taxonomies. The proposed framework was then used to evaluate whether the identified NTS were evident in a series of ward round simulations that final year general nursing students undertook as part of their training. Finally, the views of a small group of qualified nurse educators, qualified nurses and general nursing students were sought about whether the identified NTS were important and relevant to practice. The proposed NTS framework included seven categories: Communication, Decision Making, Situational Awareness, Teamwork and Task Management, Student Initiative and Responsiveness to Patient. All were rated as important and relevant to practice. The pilot study suggests that the proposed NTS framework could be used as a means of evaluating student nurse competencies in respect of many non-technical skills required for a successful ward round. Further work is required to establish the validity of the framework in educational settings and to determine the extent to which it is of use in a non-simulated ward round setting. Copyright © 2016 Elsevier Ltd. All rights reserved.

Phytoremediation capacity of poplar (Populus spp. and willow (Salix spp. clonesin relation to photosynthesis

Directory of Open Access Journals (Sweden)

Pajević Slobodanka

2009-01-01

Full Text Available Good photosynthetic features and a favorable water regimes of woody plants improve their survival and remediation potential under unfavorable ecological conditions. Accordingly, we here present results of testing plant tolerance of Pb, Cd, Ni, and diesel fuel based on gas exchange parameters and WUE of four poplar and two willow clones grown in a greenhouse on soil culture. Photosynthesis and transpiration of plants grown on soils with individually applied heavy metals decreased significantly, but this was less obvious in the case of Cd treatment. A heavy metal mixture in the soil induced significant reduction in photosynthesis (by more than 50%. Diesel fuel as the only pollutant in soil caused very strong and significant inhibition of photosynthesis and transpiration of willow clones. The results indicate genotypic specificity of all investigated physiological parameters and mark poplar clones as very useful in phytoextraction technology for the bio-cleaning of chemically polluted soils.

Reevaluation of the plant “gemstones”: Calcium oxalate crystals sustain photosynthesis under drought conditions

Science.gov (United States)

Tooulakou, Georgia; Giannopoulos, Andreas; Nikolopoulos, Dimosthenis; Bresta, Panagiota; Dotsika, Elissavet; Orkoula, Malvina G.; Kontoyannis, Christos G.; Fasseas, Costas; Liakopoulos, Georgios; Klapa, Maria I.; Karabourniotis, George

2016-01-01

ABSTRACT Land plants face the perpetual dilemma of using atmospheric carbon dioxide for photosynthesis and losing water vapors, or saving water and reducing photosynthesis and thus growth. The reason behind this dilemma is that this simultaneous exchange of gases is accomplished through the same minute pores on leaf surfaces, called stomata. In a recent study we provided evidence that pigweed, an aggressive weed, attenuates this problem exploiting large crystals of calcium oxalate as dynamic carbon pools. This plant is able to photosynthesize even under drought conditions, when stomata are closed and water losses are limited, using carbon dioxide from crystal decomposition instead from the atmosphere. Abscisic acid, an alarm signal that causes stomatal closure seems to be implicated in this function and for this reason we named this path “alarm photosynthesis.” The so-far “enigmatic,” but highly conserved and widespread among plant species calcium oxalate crystals seem to play a crucial role in the survival of plants. PMID:27471886

An Experimental Comparison of Two Methods on Photosynthesis Driving Soil Respiration: Girdling and Defoliation.

Science.gov (United States)

Jing, Yanli; Guan, Dexin; Wu, Jiabing; Wang, Anzhi; Jin, Changjie; Yuan, Fenghui

2015-01-01

Previous studies with different experimental methods have demonstrated that photosynthesis significantly influences soil respiration (RS). To compare the experimental results of different methods, RS after girdling and defoliation was measured in five-year-old seedlings of Fraxinus mandshurica from June to September. Girdling and defoliation significantly reduced RS by 33% and 25% within 4 days, and 40% and 32% within the entire treatment period, respectively. The differential response of RS to girdling and defoliation was a result of the over-compensation for RS after girdling and redistribution of stored carbon after defoliation. No significant effect on RS was observed between girdling and defoliation treatment, while the soluble sugar content in fine roots was higher in defoliation than in girdling treatment, indicating that defoliation had less compensation effect for RS after interrupting photosynthates supply. We confirm the close coupling of RS with photosynthesis and recommend defoliation for further studies to estimate the effect of photosynthesis on RS.

Ambient UV-B radiation decreases photosynthesis in high arctic Vaccinium uliginosum

Energy Technology Data Exchange (ETDEWEB)

Albert, K.R.; Ro-Poulsen, H. (Univ. of Copenhagen, Dept. of Terrestrial Ecology, Copenhagen (DK)); Mikkelsen, T.N. (Technical Univ. of Denmark, Risoe National Laboratory for Sustainable Energy, Biosystems Dept., Roskilde (DK))

2008-06-15

An UV-B-exclusion experiment was established in high arctic Zackenberg, Northeast Greenland, to investigate the possible effects of ambient UV-B on plant performance. During almost a whole growing season, canopy gas exchange and Chl fluorescence were measured on Vaccinium uliginosum (bog blueberry). Leaf area, biomass, carbon, nitrogen and UV-B-absorbing compounds were determined from a late season harvest. Compared with the reduced UV-B treatment, the plants in ambient UV-B were found to have a higher content of UV-B-absorbing compounds, and canopy net photosynthesis was as an average 23% lower during the season. By means of the JIP-test, it was found that the potential of processing light energy through the photosynthetic machinery was slightly reduced in ambient UV-B. This indicates that not only the UV-B effects on PSII may be responsible for some of the observed reduction of photosynthesis but also the effects on other parts of the photosynthetic machinery, e.g. the Calvin cycle, might be important. The 60% reduction of the UV-B irradiance used in this study implies a higher relative change in the UV-B load than many of the supplemental experiments do, but the substantial effect on photosynthesis clearly indicates that V. uliginosum is negatively affected by the current level of UV-B. (au)

Ambient UV-B radiation decreases photosynthesis in high arctic Vaccinium uliginosum.

Science.gov (United States)

Albert, Kristian R; Mikkelsen, Teis N; Ro-Poulsen, Helge

2008-06-01

An UV-B-exclusion experiment was established in high arctic Zackenberg, Northeast Greenland, to investigate the possible effects of ambient UV-B on plant performance. During almost a whole growing season, canopy gas exchange and Chl fluorescence were measured on Vaccinium uliginosum (bog blueberry). Leaf area, biomass, carbon, nitrogen and UV-B-absorbing compounds were determined from a late season harvest. Compared with the reduced UV-B treatment, the plants in ambient UV-B were found to have a higher content of UV-B-absorbing compounds, and canopy net photosynthesis was as an average 23% lower during the season. By means of the JIP-test, it was found that the potential of processing light energy through the photosynthetic machinery was slightly reduced in ambient UV-B. This indicates that not only the UV-B effects on PSII may be responsible for some of the observed reduction of photosynthesis but also the effects on other parts of the photosynthetic machinery, e.g. the Calvin cycle, might be important. The 60% reduction of the UV-B irradiance used in this study implies a higher relative change in the UV-B load than many of the supplemental experiments do, but the substantial effect on photosynthesis clearly indicates that V. uliginosum is negatively affected by the current level of UV-B.

Effects of Kaolin Application on Light Absorption and Distribution, Radiation Use Efficiency and Photosynthesis of Almond and Walnut Canopies

Science.gov (United States)

Rosati, Adolfo; Metcalf, Samuel G.; Buchner, Richard P.; Fulton, Allan E.; Lampinen, Bruce D.

2007-01-01

Background and Aims Kaolin applied as a suspension to plant canopies forms a film on leaves that increases reflection and reduces absorption of light. Photosynthesis of individual leaves is decreased while the photosynthesis of the whole canopy remains unaffected or even increases. This may result from a better distribution of light within the canopy following kaolin application, but this explanation has not been tested. The objective of this work was to study the effects of kaolin application on light distribution and absorption within tree canopies and, ultimately, on canopy photosynthesis and radiation use efficiency. Methods Photosynthetically active radiation (PAR) incident on individual leaves within the canopy of almond (Prunus dulcis) and walnut (Juglans regia) trees was measured before and after kaolin application in order to study PAR distribution within the canopy. The PAR incident on, and reflected and transmitted by, the canopy was measured on the same day for kaolin-sprayed and control trees in order to calculate canopy PAR absorption. These data were then used to model canopy photosynthesis and radiation use efficiency by a simple method proposed in previous work, based on the photosynthetic response to incident PAR of a top-canopy leaf. Key Results Kaolin increased incident PAR on surfaces of inner-canopy leaves, although there was an estimated 20 % loss in PAR reaching the photosynthetic apparatus, due to increased reflection. Assuming a 20 % loss of PAR, modelled photosynthesis and photosynthetic radiation use efficiency (PRUE) of kaolin-coated leaves decreased by only 6·3 %. This was due to (1) more beneficial PAR distribution within the kaolin-sprayed canopy, and (2) with decreasing PAR, leaf photosynthesis decreases less than proportionally, due to the curvature of the photosynthesis response-curve to PAR. The relatively small loss in canopy PRUE (per unit of incident PAR), coupled with the increased incident PAR on the leaf surface on

High-Efficiency Nitride-Based Solid-State Lighting. Final Technical Progress Report

International Nuclear Information System (INIS)

Paul T. Fini; Shuji Nakamura

2005-01-01

In this final technical progress report we summarize research accomplished during Department of Energy contract DE-FC26-01NT41203, entitled ''High-Efficiency Nitride-Based Solid-State Lighting''. Two teams, from the University of California at Santa Barbara (Principle Investigator: Dr. Shuji Nakamura) and the Lighting Research Center at Rensselaer Polytechnic Institute (led by Dr. N. Narendran), pursued the goals of this contract from thin film growth, characterization, and packaging/luminaire design standpoints. The UCSB team initially pursued the development of blue gallium nitride (GaN)-based vertical-cavity surface-emitting lasers, as well as ultraviolet GaN-based light emitting diodes (LEDs). In Year 2, the emphasis shifted to resonant-cavity light emitting diodes, also known as micro-cavity LEDs when extremely thin device cavities are fabricated. These devices have very directional emission and higher light extraction efficiency than conventional LEDs. Via the optimization of thin-film growth and refinement of device processing, we decreased the total cavity thickness to less than 1 (micro)m, such that micro-cavity effects were clearly observed and a light extraction efficiency of over 10% was reached. We also began the development of photonic crystals for increased light extraction, in particular for so-called ''guided modes'' which would otherwise propagate laterally in the device and be re-absorbed. Finally, we pursued the growth of smooth, high-quality nonpolar a-plane and m-plane GaN films, as well as blue light emitting diodes on these novel films. Initial nonpolar LEDs showed the expected behavior of negligible peak wavelength shift with increasing drive current. M-plane LEDs in particular show promise, as unpackaged devices had unsaturated optical output power of ∼ 3 mW at 200 mA drive current. The LRC's tasks were aimed at developing the subcomponents necessary for packaging UCSB's light emitting diodes, and packaging them to produce a white light

Songs about Cancer, Gene Expression, and the Biochemistry of Photosynthesis

Science.gov (United States)

Heineman, Richard H.

2018-01-01

These three biology songs can be used for educational purposes to teach about biochemical concepts. They touch on three different topics: (1) cancer progression and germ cells, (2) gene expression, promoters, and repressors, and (3) electronegativity and the biochemical basis of photosynthesis.

Selective effects of H2O2 on cyanobacterial photosynthesis

Czech Academy of Sciences Publication Activity Database

Drábková, Michaela; Matthijs, H. C. P.; Admiraal, W.; Maršálek, Blahoslav

2007-01-01

Roč. 45, č. 3 (2007), s. 363-369 ISSN 0300-3604 Grant - others:-(XE) EVK2-CT-2002-57004 Institutional research plan: CEZ:AV0Z60050516 Keywords : hydrogen peroxide * cyanobacteria * photosynthesis Subject RIV: EF - Botanics Impact factor: 0.976, year: 2007

A list of personal perspectives with selected quotations, along with lists of tributes, historical notes, Nobel and Kettering awards related to photosynthesis.

Science.gov (United States)

Krogmann, David W

2002-01-01

The history of photosynthesis research can be found in original papers and books. However, a special history is available from the prefatory chapters and the personal perspectives of various researchers who published them in several journals over the last 40 years. We have compiled a list of such perspectives published since 1964. Selection is not easy, especially of authors who were not directly engaged in photosynthesis research; some are included for their special insights related to central issues in the study of photosynthesis. Our journal, Photosynthesis Research, contains other valuable historic data in the occasional tributes, obituaries and historical notes, that have been published. Lists of these items are included. This article ends by listing the Nobel prizes related to photosynthesis and the Kettering Awards for Excellence in Photosynthesis Research. Wherever possible, a web page address is provided. The web page addresses have been taken from the article 'Photosynthesis and the Web: 2001' by Larry Orr and Govindjee, available at http://www.life.uiuc.edu/govindjee/photoweb and at http://photoscience.la.asu.edu/photosyn/ photoweb/default.html.When I find a bit of leisureI trifle with my papers.This is one of the lesserfrailities.'- Horace, Satires I, IV.

Photosynthesis and sink activity of wasp-induced galls in Acacia pycnantha.

Science.gov (United States)

Dorchin, Netta; Cramer, Michael D; Hoffmann, John H

2006-07-01

Although insect galls are widely known to influence source-sink relationships in plants, the relationship between photosynthesis and gall activity has not been extensively studied. In this study we used 14CO2, photosynthesis, and respiration measurements to examine the capacity of bud galls induced by the wasp Trichilogaster signiventris (Pteromalidae) as carbon sinks in Acacia pycnantha. Galls of this species develop either in vegetative or reproductive buds, depending on the availability of tissues at different times of the year, and effectively eliminate seed production by the plant. Photosynthetic rates in phyllodes subtending clusters of galls were greater than rates in control phyllodes, a result we attributed to photosynthesis compensating for increased carbon demand by the galls. Contrary to previous studies, we found that photosynthesis within galls contributed substantially to the carbon budgets of the galls, particularly in large, mature galls, which exhibited lower specific respiration rates allowing for a net carbon gain in the light. To determine the sink capacity and competitive potential of galls, we measured the proportion of specific radioactivity in galls originating from either vegetative or reproductive buds and found no difference between them. The proportion of the total amount of phyllode-derived 14C accumulated in both clustered and solitary galls was less than that in fruits. Galls and fruits were predominantly reliant on subtending rather than on distant phyllodes for photosynthate. Solitary galls that developed in vegetative buds constituted considerably stronger sinks than galls in clusters on inflorescences where there was competition between galls or fruits for resources from the subtending phyllode. Wasps developing in solitary vegetative galls were correspondingly significantly larger than those from clustered galls. We conclude that, in the absence of inflorescence buds during summer and fall, the ability of the wasps to cause gall

DNA sequence analysis of the photosynthesis region of Rhodobacter sphaeroides 2.4.1T

OpenAIRE

Choudhary, M.; Kaplan, Samuel

2000-01-01

This paper describes the DNA sequence of the photosynthesis region of Rhodobacter sphaeroides 2.4.1T. The photosynthesis gene cluster is located within a ~73 kb AseI genomic DNA fragment containing the puf, puhA, cycA and puc operons. A total of 65 open reading frames (ORFs) have been identified, of which 61 showed significant similarity to genes/proteins of other organisms while only four did not reveal any significant sequence similarity to any gene/protein sequences in the database. The da...

Polar source analysis : technical memorandum

Science.gov (United States)

2017-09-29

The following technical memorandum describes the development, testing and analysis of various polar source data sets. The memorandum also includes recommendation for potential inclusion in future releases of AEDT. This memorandum is the final deliver...

Enhanced Thermostability of Arabidopsis Rubisco Activase Improves Photosynthesis and Growth Rates under Moderate Heat Stress[OA

Science.gov (United States)

Kurek, Itzhak; Chang, Thom Kai; Bertain, Sean M.; Madrigal, Alfredo; Liu, Lu; Lassner, Michael W.; Zhu, Genhai

2007-01-01

Plant photosynthesis declines when the temperature exceeds its optimum range. Recent evidence indicates that the reduction in photosynthesis is linked to ribulose-1,5-bis-phosphate carboxylase/oxygenase (Rubisco) deactivation due to the inhibition of Rubisco activase (RCA) under moderately elevated temperatures. To test the hypothesis that thermostable RCA can improve photosynthesis under elevated temperatures, we used gene shuffling technology to generate several Arabidopsis thaliana RCA1 (short isoform) variants exhibiting improved thermostability. Wild-type RCA1 and selected thermostable RCA1 variants were introduced into an Arabidopsis RCA deletion (Δrca) line. In a long-term growth test at either constant 26°C or daily 4-h 30°C exposure, the transgenic lines with the thermostable RCA1 variants exhibited higher photosynthetic rates, improved development patterns, higher biomass, and increased seed yields compared with the lines expressing wild-type RCA1 and a slight improvement compared with untransformed Arabidopsis plants. These results provide clear evidence that RCA is a major limiting factor in plant photosynthesis under moderately elevated temperatures and a potential target for genetic manipulation to improve crop plants productivity under heat stress conditions. PMID:17933901

The effect of irradiance on long-term skeletal growth and net photosynthesis in Galaxea fascicularis under four light conditions.

NARCIS (Netherlands)

Schutter, M.; Velthoven, van B.; Janse, M.; Osinga, R.; Janssen, M.G.J.; Wijffels, R.H.; Verreth, J.A.J.

2008-01-01

The relation between irradiance, skeletal growth and net photosynthesis was studied for the scleractinian coral Galaxea fascicularis to provide experimental evidence for mediation of light-enhanced calcification through photosynthesis. The hypothesis was tested that skeletal growth and

Effect of traffic pollution on photosynthesis | Durrani | Journal of ...

African Journals Online (AJOL)

Vehicular exhaust is considered as one of the worst form of environmental pollution. To assess the effect of traffic pollution on photosynthesis, leaf samples of four different types of plants at different distances from the busy traffic road were collected from Wah. The samples consisted of sunny, shady and semi shady leaves of ...

Vehicle infrastructure integration proof of concept : technical description--vehicle : final report

Science.gov (United States)

2009-05-19

This report provides the technical description of the VII system developed for the Cooperative Agreement VII Program between the USDOT and the VII Consortium. The basic architectural elements are summarized and detailed descriptions of the hardware a...

The pineapple genome and the evolution of CAM photosynthesis.

Science.gov (United States)

Ming, Ray; VanBuren, Robert; Wai, Ching Man; Tang, Haibao; Schatz, Michael C; Bowers, John E; Lyons, Eric; Wang, Ming-Li; Chen, Jung; Biggers, Eric; Zhang, Jisen; Huang, Lixian; Zhang, Lingmao; Miao, Wenjing; Zhang, Jian; Ye, Zhangyao; Miao, Chenyong; Lin, Zhicong; Wang, Hao; Zhou, Hongye; Yim, Won C; Priest, Henry D; Zheng, Chunfang; Woodhouse, Margaret; Edger, Patrick P; Guyot, Romain; Guo, Hao-Bo; Guo, Hong; Zheng, Guangyong; Singh, Ratnesh; Sharma, Anupma; Min, Xiangjia; Zheng, Yun; Lee, Hayan; Gurtowski, James; Sedlazeck, Fritz J; Harkess, Alex; McKain, Michael R; Liao, Zhenyang; Fang, Jingping; Liu, Juan; Zhang, Xiaodan; Zhang, Qing; Hu, Weichang; Qin, Yuan; Wang, Kai; Chen, Li-Yu; Shirley, Neil; Lin, Yann-Rong; Liu, Li-Yu; Hernandez, Alvaro G; Wright, Chris L; Bulone, Vincent; Tuskan, Gerald A; Heath, Katy; Zee, Francis; Moore, Paul H; Sunkar, Ramanjulu; Leebens-Mack, James H; Mockler, Todd; Bennetzen, Jeffrey L; Freeling, Michael; Sankoff, David; Paterson, Andrew H; Zhu, Xinguang; Yang, Xiaohan; Smith, J Andrew C; Cushman, John C; Paull, Robert E; Yu, Qingyi

2015-12-01

Pineapple (Ananas comosus (L.) Merr.) is the most economically valuable crop possessing crassulacean acid metabolism (CAM), a photosynthetic carbon assimilation pathway with high water-use efficiency, and the second most important tropical fruit. We sequenced the genomes of pineapple varieties F153 and MD2 and a wild pineapple relative, Ananas bracteatus accession CB5. The pineapple genome has one fewer ancient whole-genome duplication event than sequenced grass genomes and a conserved karyotype with seven chromosomes from before the ρ duplication event. The pineapple lineage has transitioned from C3 photosynthesis to CAM, with CAM-related genes exhibiting a diel expression pattern in photosynthetic tissues. CAM pathway genes were enriched with cis-regulatory elements associated with the regulation of circadian clock genes, providing the first cis-regulatory link between CAM and circadian clock regulation. Pineapple CAM photosynthesis evolved by the reconfiguration of pathways in C3 plants, through the regulatory neofunctionalization of preexisting genes and not through the acquisition of neofunctionalized genes via whole-genome or tandem gene duplication.

Growth but not photosynthesis response of a host plant to infection by a holoparasitic plant depends on nitrogen supply.

Directory of Open Access Journals (Sweden)

Hao Shen

Full Text Available Parasitic plants can adversely influence the growth of their hosts by removing resources and by affecting photosynthesis. Such negative effects depend on resource availability. However, at varied resource levels, to what extent the negative effects on growth are attributed to the effects on photosynthesis has not been well elucidated. Here, we examined the influence of nitrogen supply on the growth and photosynthesis responses of the host plant Mikania micrantha to infection by the holoparasite Cuscuta campestris by focusing on the interaction of nitrogen and infection. Mikania micrantha plants fertilized at 0.2, 1 and 5 mM nitrate were grown with and without C. campestris infection. We observed that the infection significantly reduced M. micrantha growth at each nitrate fertilization and more severely at low than at high nitrate. Such alleviation at high nitrate was largely attributed to a stronger influence of infection on root biomass at low than at high nitrate fertilization. However, although C. campestris altered allometry and inhibited host photosynthesis, the magnitude of the effects was independent of nitrate fertilizations. The infection reduced light saturation point, net photosynthesis at saturating irradiances, apparent quantum yield, CO2 saturated rate of photosynthesis, carboxylation efficiency, the maximum carboxylation rate of Rubisco, and maximum light-saturated rate of electron transport, and increased light compensation point in host leaves similarly across nitrate levels, corresponding to a similar magnitude of negative effects of the parasite on host leaf soluble protein and Rubisco concentrations, photosynthetic nitrogen use efficiency and stomatal conductance across nitrate concentrations. Thus, the more severe inhibition in host growth at low than at high nitrate supplies cannot be attributed to a greater parasite-induced reduction in host photosynthesis, but the result of a higher proportion of host resources

Growth but Not Photosynthesis Response of a Host Plant to Infection by a Holoparasitic Plant Depends on Nitrogen Supply

Science.gov (United States)

Shen, Hao; Xu, Shu-Jun; Hong, Lan; Wang, Zhang-Ming; Ye, Wan-Hui

2013-01-01

Parasitic plants can adversely influence the growth of their hosts by removing resources and by affecting photosynthesis. Such negative effects depend on resource availability. However, at varied resource levels, to what extent the negative effects on growth are attributed to the effects on photosynthesis has not been well elucidated. Here, we examined the influence of nitrogen supply on the growth and photosynthesis responses of the host plant Mikania micrantha to infection by the holoparasite Cuscuta campestris by focusing on the interaction of nitrogen and infection. Mikania micrantha plants fertilized at 0.2, 1 and 5 mM nitrate were grown with and without C. campestris infection. We observed that the infection significantly reduced M. micrantha growth at each nitrate fertilization and more severely at low than at high nitrate. Such alleviation at high nitrate was largely attributed to a stronger influence of infection on root biomass at low than at high nitrate fertilization. However, although C. campestris altered allometry and inhibited host photosynthesis, the magnitude of the effects was independent of nitrate fertilizations. The infection reduced light saturation point, net photosynthesis at saturating irradiances, apparent quantum yield, CO2 saturated rate of photosynthesis, carboxylation efficiency, the maximum carboxylation rate of Rubisco, and maximum light-saturated rate of electron transport, and increased light compensation point in host leaves similarly across nitrate levels, corresponding to a similar magnitude of negative effects of the parasite on host leaf soluble protein and Rubisco concentrations, photosynthetic nitrogen use efficiency and stomatal conductance across nitrate concentrations. Thus, the more severe inhibition in host growth at low than at high nitrate supplies cannot be attributed to a greater parasite-induced reduction in host photosynthesis, but the result of a higher proportion of host resources transferred to the parasite at

Energy transfer in light-adapted photosynthetic membranes: from active to saturated photosynthesis.

Science.gov (United States)

Fassioli, Francesca; Olaya-Castro, Alexandra; Scheuring, Simon; Sturgis, James N; Johnson, Neil F

2009-11-04

In bacterial photosynthesis light-harvesting complexes, LH2 and LH1 absorb sunlight energy and deliver it to reaction centers (RCs) with extraordinarily high efficiency. Submolecular resolution images have revealed that both the LH2:LH1 ratio, and the architecture of the photosynthetic membrane itself, adapt to light intensity. We investigate the functional implications of structural adaptations in the energy transfer performance in natural in vivo low- and high-light-adapted membrane architectures of Rhodospirillum photometricum. A model is presented to describe excitation migration across the full range of light intensities that cover states from active photosynthesis, where all RCs are available for charge separation, to saturated photosynthesis where all RCs are unavailable. Our study outlines three key findings. First, there is a critical light-energy density, below which the low-light adapted membrane is more efficient at absorbing photons and generating a charge separation at RCs, than the high-light-adapted membrane. Second, connectivity of core complexes is similar in both membranes, suggesting that, despite different growth conditions, a preferred transfer pathway is through core-core contacts. Third, there may be minimal subareas on the membrane which, containing the same LH2:LH1 ratio, behave as minimal functional units as far as excitation transfer efficiency is concerned.

Final Scientific and Technical Report State and Regional Biomass Partnerships

Energy Technology Data Exchange (ETDEWEB)

Handley, Rick; Stubbs, Anne D.

2008-12-29

The Northeast Regional Biomass Program successfully employed a three pronged approach to build the regional capacity, networks, and reliable information needed to advance biomass and bioenergy technologies and markets. The approach included support for state-based, multi-agency biomass working groups; direct technical assistance to states and private developers; and extensive networking and partnership-building activities to share objective information and best practices.

NUSC Technical Publications Guide.

Science.gov (United States)

1985-05-01

Facility personnel especially that of A. Castelluzzo, E. Deland, J. Gesel , and E. Szlosek (all of Code 4343). Reviewed and Approved: 14 July 1980 D...their technical content and format. Review and approve the manual outline, the review manuscript, and the final camera - reproducible copy. Conduct in

Photosynthesis and Ribulose 1,5-Bisphosphate Concentrations in Intact Leaves of Xanthium strumarium L. 1

Science.gov (United States)

Mott, Keith A.; Jensen, Richard G.; O'Leary, James W.; Berry, Joseph A.

1984-01-01

The interacting effects of the rate of ribulose 1,5-bisphosphate (RuBP) regeneration and the rate of RuBP utilization as influenced by the amount and activation of RuBP carboxylase on photosynthesis and RuBP concentrations were resolved in experiments which examined the kinetics of the response of photosynthesis and RuBP concentrations after step changes from a rate-saturating to a rate-limiting light intensity in Xanthium strumarium. Because RuBP carboxylase requires several minutes to deactivate in vivo, it was possible to observe the effect of reducing the rate of RuBP regeneration on the RuBP concentration at constant enzyme activation state by sampling very soon after reducing the light intensity. Samples taken over longer time periods showed the effect of changes in enzyme activation at constant RuBP regeneration rate on RuBP concentration and photosynthetic rate. Within 15 s of lowering the light intensity from 1500 to 600 microEinsteins per square meter per second the RuBP concentration in the leaves dropped below the enzyme active site concentration, indicating that RuBP regeneration rate was limiting for photosynthesis. After longer intervals of time, the RuBP concentration in the leaf increased as the RuBP carboxylase assumed a new steady state activation level. No change in the rate of photosynthesis was observed during the interval that RuBP concentration increased. It is concluded that the rate of photosynthesis at the lower light intensity was limited by the rate of RuBP regeneration and that parallel changes in the activation of RuBP carboxylase occurred such that concentrations of RuBP at steady state were not altered by changes in light intensity. PMID:16663982

Model for expressing leaf photosynthesis in terms of weather variables

African Journals Online (AJOL)

A theoretical mathematical model for describing photosynthesis in individual leaves in terms of weather variables is proposed. The model utilizes a series of efficiency parameters, each of which reflect the fraction of potential photosynthetic rate permitted by the different environmental elements. These parameters are useful ...

Phenotyping of field-grown wheat in the UK highlights contribution of light response of photosynthesis and flag leaf longevity to grain yield.

Science.gov (United States)

Carmo-Silva, Elizabete; Andralojc, P John; Scales, Joanna C; Driever, Steven M; Mead, Andrew; Lawson, Tracy; Raines, Christine A; Parry, Martin A J

2017-06-15

Improving photosynthesis is a major target for increasing crop yields and ensuring food security. Phenotyping of photosynthesis in the field is critical to understand the limits to crop performance in agricultural settings. Yet, detailed phenotyping of photosynthetic traits is relatively scarce in field-grown wheat, with previous studies focusing on narrow germplasm selections. Flag leaf photosynthetic traits, crop development, and yield traits were compared in 64 field-grown wheat cultivars in the UK. Pre-anthesis and post-anthesis photosynthetic traits correlated significantly and positively with grain yield and harvest index (HI). These traits included net CO2 assimilation measured at ambient CO2 concentrations and a range of photosynthetic photon flux densities, and traits associated with the light response of photosynthesis. In most cultivars, photosynthesis decreased post-anthesis compared with pre-anthesis, and this was associated with decreased Rubisco activity and abundance. Heritability of photosynthetic traits suggests that phenotypic variation can be used to inform breeding programmes. Specific cultivars were identified with traits relevant to breeding for increased crop yields in the UK: pre-anthesis photosynthesis, post-anthesis photosynthesis, light response of photosynthesis, and Rubisco amounts. The results indicate that flag leaf longevity and operating photosynthetic activity in the canopy can be further exploited to maximize grain filling in UK bread wheat. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Medium energy measurements of N-N parameters. Final technical report, April 1, 1994--September 30, 1996

International Nuclear Information System (INIS)

Ambrose, D.; Betts, W.; Coffey, P.; Glass, G.; McDonough, J.; Riley, P.; Tang, J.L.

1998-08-01

This document is a final technical report describing the accomplishments of the medium/high energy nuclear physics research program at the University of Texas at Austin. The research program had four main thrusts, only one of which can be considered as measurements of N-N parameters: (1) finishing the data analyses associated with recent LAMPF and TRIUMPF N-N experiments, whose overall purpose has been the determination of the nucleon-nucleon amplitudes, both for isospin 0 and 1 at medium energies; (2) continuing work on BNL E871, a search for rare decay modes of the K L ; (3) work on the RHIC-STAR project, an experiment to create and study a quark gluon plasma and nuclear matter at high energy density; (4) beginning a new AGS experiment (E896) which will search for the lowest mass state of the predicted strange di-baryons, the Ho, and other exotic states of nuclear matter through nucleus-nucleus collisions

Can net photosynthesis and water relations provide a clue on the ...

African Journals Online (AJOL)

user

2011-02-28

Feb 28, 2011 ... cuvette of the Licor-6400 portable photosynthesis system (Licor,. Lincoln, NE, USA). The leaf ... We would like to thank KOICA for the financial supoort. We thank the KOTUCOP (Korea-Tunisian Coperation. Project) research ...

Artificial photosynthesis: biomimetic approaches to solar energy conversion and storage.

Science.gov (United States)

Kalyanasundaram, K; Graetzel, M

2010-06-01

Using sun as the energy source, natural photosynthesis carries out a number of useful reactions such as oxidation of water to molecular oxygen and fixation of CO(2) in the form of sugars. These are achieved through a series of light-induced multi-electron-transfer reactions involving chlorophylls in a special arrangement and several other species including specific enzymes. Artificial photosynthesis attempts to reconstruct these key processes in simpler model systems such that solar energy and abundant natural resources can be used to generate high energy fuels and restrict the amount of CO(2) in the atmosphere. Details of few model catalytic systems that lead to clean oxidation of water to H(2) and O(2), photoelectrochemical solar cells for the direct conversion of sunlight to electricity, solar cells for total decomposition of water and catalytic systems for fixation of CO(2) to fuels such as methanol and methane are reviewed here. Copyright 2010 Elsevier Ltd. All rights reserved.

NTRCI Legacy Engine Research and Development Project Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Smith-Holbert, Connie [National Transportation Research Center, Inc., Knoxville, TN (United States); Petrolino, Joseph [National Transportation Research Center, Inc., Knoxville, TN (United States); Watkins, Bart [Power Source Technologies Inc., Corvallis, OR (United States); Irick, David [Power Source Technologies Inc., Corvallis, OR (United States)

2011-12-31

The Legacy engine is a completely new design, transitional diesel engine, replacing the reciprocating engine with a rotary engine. The Legacy engine offers significant advances over conventional internal combustion engines in 1) power to weight ratio; 2) multiple fuel acceptance; 3) fuel economy; and 4) environmental compliance. These advances are achieved through a combination of innovative design geometry, rotary motion, aspiration simplicity, and manufacturing/part simplicity. The key technical challenge to the Legacy engine's commercialization, and the focus of this project, was the development of a viable roton tip seal. The PST concept for the roton tip seal was developed into a manufacturable design. The design was evaluated using a custom designed and fabricated seal test fixture and further refined. This design was incorporated into the GEN2.5A prototype and tested for achievable compression pressure. The Decision Point at the end of Phase 1 of the project (described below) was to further optimize the existing tip seal design. Enhancements to the tip seal design were incorporated into the GEN2.5B prototype and tested and evaluated using the iterative research strategy described below. Compression pressures adequate for compression ignition of diesel fuel were achieved, although not consistently in all combustion volumes. The variation in compression pressures was characterized versus design features. As the roton tip seal performance was improved, results pointed toward inadequate performance of the housing side seals. Enhancement of the housing side seal system was accomplished using a custom designed side seal test fixture. The design enhancements developed with the test fixture were also incorporated into the GEN2.5B prototype and tested and evaluated using the iterative research strategy described below. Finally, to simplify the requirements for the roton tip seals and to enhance the introduction and combustion of fuel, a flush-mount fuel injector

Final Scientific/Technical Report

Energy Technology Data Exchange (ETDEWEB)

Brown, R. C.; McCarley, T. M.

2006-05-04

. Platform teams organize faculty and students for cross-disciplinary, systems-oriented research and collaborative learning. To date, nine platforms have been developed, although these will most likely be reorganized into a smaller number of broader topics. In the spring of 2004, BRT faculty initiated a regional partnership and collaborative learning program with colleagues at the University of Minnesota, Kansas State University, and South Dakota State University to develop distance education courses in biorenewable resources and technology. As a fledgling graduate program, the BRT graduate program didn’t have the breadth of resources to offer a large number of courses in biorenewables. Other schools faced a similar problem. The academic consortium as first conceived would allow students from the member schools to enroll in biorenewables courses from any of the participating schools, which would assure the necessary enrollment numbers to offer specialized course work. Since its inception, the collaborative curriculum partnership has expanded to include Louisiana State University and the University of Wisconsin. A second international curriculum development campaign was also initiated in the spring of 2004. In particular, several BRT faculty teamed with colleagues at the University of Arkansas, University of Washington, University of Gent (Belgium), National Polytechnic Institute of Toulouse (France), and Technical University of Graz (Austria) to develop an EU-US exchange program in higher education and vocational education/training (entitled “Renewable Resources and Clean Technology”).

Continuous Measurements of Canopy-level Solar-Induced Chlorophyll Fluorescence for Inferring Diurnal and Seasonal Dynamics of Photosynthesis in Crop Fields in the Midwestern USA

Science.gov (United States)

Miao, G.; Guan, K.; Yang, X.; Bernacchi, C.; DeLucia, E. H.; Cai, Y.; Masters, M. D.; Peng, B.

2016-12-01

Plants emitted photons of red and far-red light, called chlorophyll fluorescence, after sunlight absorption for photosynthesis. This solar-induced fluorescence (SIF) is generated simultaneously while plants actively photosynthesize. The link between photosynthesis and SIF resulting from the competition for the same excitation energy has long been investigated and applied for inferring the rate of photosynthesis. Recent development of continuous SIF observational technology is furthering the inferring potential as well as our understandings of fluctuations of SIF and photosynthesis with changes in environmental conditions. To better understand this photosynthesis-SIF link at multiple time scales and their relationships with environmental drivers, we deployed two newly developed tower-based SIF systems (FluoSpec) in a corn (Zea mays L., C4 plant) field and a soybean (Glycine max L., C3 plant) field at University of Illinois Energy Farm and conducted continuous near-surface SIF measurements at canopy scale from mid-growing season of 2016. Eddy covariance flux towers were installed in parallel at both sites for canopy-scale gas exchange measurements. Relationship between SIF and flux tower photosynthesis will be analyzed to derive the empirical models for photosynthesis retrieval from SIF signals. Preliminary results indicate that canopy SIF can reflect diurnal and seasonal dynamics of photosynthesis. Mechanistic analysis on SIF fluctuations and responses to environmental variations will be conducted as well for a closer look at mechanism of photosynthetic responses. Corn and soybean SIF and photosynthesis-SIF relationship will be compared to investigate the difference between C4 and C3 plants.

Global and Time-Resolved Monitoring of Crop Photosynthesis with Chlorophyll Fluorescence

Science.gov (United States)

Guanter, Luis; Zhang, Yongguang; Jung, Martin; Joiner, Joanna; Voigt, Maximilian; Berry, Joseph A.; Frankenberg, Christian; Huete, Alfredo R.; Zarco-Tejada, Pablo; Lee, Jung-Eun;

Diffusive boundary layers and photosynthesis of the epilithic algal community of coral reefs

DEFF Research Database (Denmark)

Larkum, Anthony W.D.; Koch, Eva-Maria W.; Kühl, Michael

2003-01-01

The effects of mass transfer resistance due to the presence of a diffusive boundary layer on the photosynthesis of the epilithic algal community (EAC) of a coral reef were studied. Photosynthesis and respiration of the EAC of dead coral surfaces were investigated for samples from two locations......: the Gulf of Aqaba, Eilat (Israel), and One Tree Reef on the Great Barrier Reef (Australia). Microsensors were used to measure O2 and pH at the EAC surface and above. Oxygen profiles in the light and dark indicated a diffusive boundary layer (DBL) thickness of 180–590 µm under moderate flow (~0.08 m s-1...

Inhibition of seagrass photosynthesis by ultraviolet-B radiation

International Nuclear Information System (INIS)

Trocine, R.P.; Rice, J.D.; Wells, G.N.

1981-01-01

Effects of ultraviolet-B radiation on the photosynthesis of seagrasses (Halophila engelmanni Aschers, Halodule wrightii Aschers, and Syringodium filiforme (Kuetz) were examined. The intrinsic tolerance of each seagrass to ultraviolet-B, the presence and effectiveness of photorepair mechanisms to ultraviolet-B-induced photosynthetic inhibition, and the role of epiphytic growth as a shield from ultraviolet-B were investigated. Halodule was found to possess the greatest photosynthetic tolerance for ultraviolet-B. Photosynthesis in Syringodium was slightly more sensitive to ultraviolet-B while Halophila showed relatively little photosynthetic tolerance. Evidence for a photorepair mechanism was found only in Halodule. Syringodium appeared to rely primarily on a thick epidermal cell layer to reduce photosynthetic damage. Halophila seemed to have no morphological or photorepair capabilities to deal with ultraviolet-B. This species appeared to rely on epiphytic and detrital shielding and the shade provided by other seagrasses to reduce ultraviolet-B irradiation to tolerable levels. The presence of epiphytes on leaf surfaces was found to reduce the extent of photosynthetic inhibition from ultraviolet-B exposure in all species. Halophila appears to obtain an increased photosynthetic tolerance to ultraviolet-B as an indirect benefit of chloroplast clumping to avoid photo-oxidation by intense levels of photosynthetically active radiation

Do plastic particles affect microalgal photosynthesis and growth?

Science.gov (United States)

Sjollema, Sascha B; Redondo-Hasselerharm, Paula; Leslie, Heather A; Kraak, Michiel H S; Vethaak, A Dick

2016-01-01

The unbridled increase in plastic pollution of the world's oceans raises concerns about potential effects these materials may have on microalgae, which are primary producers at the basis of the food chain and a major global source of oxygen. Our current understanding about the potential modes and mechanisms of toxic action that plastic particles exert on microalgae is extremely limited. How effects might vary with particle size and the physico-chemical properties of the specific plastic material in question are equally unelucidated, but may hold clues to how toxicity, if observed, is exerted. In this study we selected polystyrene particles, both negatively charged and uncharged, and three different sizes (0.05, 0.5 and 6μm) for testing the effects of size and material properties. Microalgae were exposed to different polystyrene particle sizes and surface charges for 72h. Effects on microalgal photosynthesis and growth were determined by pulse amplitude modulation fluorometry and flow cytometry, respectively. None of the treatments tested in these experiments had an effect on microalgal photosynthesis. Microalgal growth was negatively affected (up to 45%) by uncharged polystyrene particles, but only at high concentrations (250mg/L). Additionally, these adverse effects were demonstrated to increase with decreasing particle size. Copyright © 2015 Elsevier B.V. All rights reserved.

Inhibition of photosynthesis by carbon monoxide and suspension of the carbon monoxide inhibition by light

Energy Technology Data Exchange (ETDEWEB)

Gewitz, H S; Voelker, W

1963-08-01

The experimental subject was the autotroph Chlorella pyrenoidosa. It was found that growth conditions determine whether the alga is inhibited by carbon monoxide or not. Respiration and photosynthesis are inhibited by carbon monoxide if the cells have grown rapidly under high light intensities. The inhibition of respiration and photosynthesis found in such cells is completely reversible. The inhibition depends not only on carbon monoxide pressure, but also on the oxygen pressure prevailing at the same time. 5 references, 1 figure, 3 tables.

Technical assistance for Meharry Medical College Energy Efficiency Project. Final project status and technical report

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-05-08

This report presents the results of a program to provide technical assistance to Meharry Medical College. The purpose of the program is to facilitate Meharry`s effort to finance a campus-wide facility retrofit. The US Department of Energy (USDOE) funded the program through a grant to the Tennessee Department of Economic and Community Development (TECD). The University of Memphis-Technology and Energy Services (UM-TES), under contract to TECD, performed program services. The report has three sections: (1) introduction; (2) project definition, financing, and participants; and (3) opportunities for federal participation.

Fundamental studies of the chemical vapor deposition of diamond. Final technical report, April 1, 1988--December 31, 1994

Energy Technology Data Exchange (ETDEWEB)

Nix, W.D.

1995-05-01

We submit here a final technical report for the research program entitled: Fundamental Studies of the Chemical Vapor Deposition of Diamond, DOE Grant No. DE-FG05-88ER45345-M006. This research program was initiated in 1988 under the direction of the late Professor David A. Stevenson and was renewed in 1992. Unfortunately, at the end of 1992, just as the last phase of this work was getting underway, Professor Stevenson learned that he had developed mesothelioma, a form of cancer based on asbestos. Professor Stevenson died from that disease in February of 1994. Professor William D. Nix, the Chairman of the Materials Science department at Stanford was named the Principal Investigator. Professor Nix has assembled this final technical report. Much of the work of this grant was conducted by Mr. Paul Dennig, a graduate student who will receive his Ph.D. degree from Stanford in a few months. His research findings are described in the chapters of this report and in the papers published over the past few years. The main discovery of this work was that surface topology plays a crucial role in the nucleation of diamond on silicon. Dennig and his collaborators demonstrated this by showing that diamond nucleates preferentially at the tips of asperities on a silicon surface rather than in the re-entrant comers at the base of such asperities. Some of the possible reasons for this effect are described in this report. The published papers listed on the next page of this report also describe this research. Interested persons can obtain copies of these papers from Professor Nix at Stanford. A full account of all of the research results obtained in this work is given in the regular chapters that follow this brief introduction. In addition, interested readers will want to consult Mr. Dennig`s Ph.D. dissertation when it is made available later this year.

Acetylome analysis reveals the involvement of lysine acetylation in photosynthesis and carbon metabolism in the model cyanobacterium Synechocystis sp. PCC 6803.

Science.gov (United States)

Mo, Ran; Yang, Mingkun; Chen, Zhuo; Cheng, Zhongyi; Yi, Xingling; Li, Chongyang; He, Chenliu; Xiong, Qian; Chen, Hui; Wang, Qiang; Ge, Feng

2015-02-06

Cyanobacteria are the oldest known life form inhabiting Earth and the only prokaryotes capable of performing oxygenic photosynthesis. Synechocystis sp. PCC 6803 (Synechocystis) is a model cyanobacterium used extensively in research on photosynthesis and environmental adaptation. Posttranslational protein modification by lysine acetylation plays a critical regulatory role in both eukaryotes and prokaryotes; however, its extent and function in cyanobacteria remain unexplored. Herein, we performed a global acetylome analysis on Synechocystis through peptide prefractionation, antibody enrichment, and high accuracy LC-MS/MS analysis; identified 776 acetylation sites on 513 acetylated proteins; and functionally categorized them into an interaction map showing their involvement in various biological processes. Consistent with previous reports, a large fraction of the acetylation sites are present on proteins involved in cellular metabolism. Interestingly, for the first time, many proteins involved in photosynthesis, including the subunits of phycocyanin (CpcA, CpcB, CpcC, and CpcG) and allophycocyanin (ApcA, ApcB, ApcD, ApcE, and ApcF), were found to be lysine acetylated, suggesting that lysine acetylation may play regulatory roles in the photosynthesis process. Six identified acetylated proteins associated with photosynthesis and carbon metabolism were further validated by immunoprecipitation and Western blotting. Our data provide the first global survey of lysine acetylation in cyanobacteria and reveal previously unappreciated roles of lysine acetylation in the regulation of photosynthesis. The provided data set may serve as an important resource for the functional analysis of lysine acetylation in cyanobacteria and facilitate the elucidation of the entire metabolic networks and photosynthesis process in this model cyanobacterium.

[Effects of temperature regime on low-light tolerance of Cucumis sativus seedling leaves in their photosynthesis].

Science.gov (United States)

Li, Wei; Sui, Xiao-lei; Zhang, Zhen-xian

2008-12-01

In a phytotron, the effects of three temperature regimes (day/night 25 degrees C/18 degrees C, optimal temperature; 15 degrees C/9 degrees C, suboptimal temperature; and 9 degrees C/7 degrees C, low temperature) on the low-light (75-85 micromol x m(-2) x s(-1)) tolerance of two Cucumis sativus cultivars (shade-susceptible Jinyan 2 and shade-tolerant Deltastar) seedling leaves in their photosynthesis were studied. The results showed that under low light, the SPAD, net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), water use efficiency (WUE), actual photochemical efficiency of PS II in the light (phi(PS II)), and photochemical quenching of chlorophyll fluorescence (q(p)) of cucumber leaves decreased, with the decrement getting more with decreasing temperature, while the superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities were in adverse. During the recovery process after low-light stress relieved, the parameters of gas exchange and chlorophyll fluorescence of the leaves recovered gradually, and the recovery of some gas exchange parameters lagged to that of chlorophyll fluorescence parameters. Under low light, the lower the temperature, the more damage the photosynthesis apparatus suffered, and the lesser tolerance to low light the cucumber leaves had in their photosynthesis. During the low temperature and low light treatment period, the decrease of Pn, phi(PS II), and q(p) was more obvious for Jinyan 2 than for Deltastar; and during the relief period, the recovery of these parameters was slower for Jinyan 2 than for Deltastar. It was indicated that Jinyan 2 had weaker tolerance to low temperature and/or low light in its photosynthesis than Deltastar.

Changes in photosynthesis, mesophyll conductance to CO2, and isoprenoid emissions in Populus nigra plants exposed to excess nickel

International Nuclear Information System (INIS)

Velikova, Violeta; Tsonev, Tsonko; Loreto, Francesco; Centritto, Mauro

2011-01-01

Poplar (Populus nigra) plants were grown hydroponically with 30 and 200 μM Ni (Ni 30 and Ni 200 ). Photosynthesis limitations and isoprenoid emissions were investigated in two leaf types (mature and developing). Ni stress significantly decreased photosynthesis, and this effect depended on the leaf Ni content, which was lower in mature than in developing leaves. The main limitations to photosynthesis were attributed to mesophyll conductance and metabolism impairment. In Ni-stressed developing leaves, isoprene emission was significantly stimulated. We attribute such stimulation to the lower chloroplastic [CO 2 ] than in control leaves. However chloroplastic [CO 2 ] did not control isoprene emission in mature leaves. Ni stress induced the emission of cis-β-ocimene in mature leaves, and of linalool in both leaf types. Induced biosynthesis and emission of isoprenoids reveal the onset of antioxidant processes that may also contribute to reduce Ni stress, especially in mature poplar leaves. - Graphical abstract: Visible damage caused by Ni treatment. 1 - Ni 0 (control plants); 2 - Ni 200 ; M = mature and D = developing Populus nigra leaves. Display Omitted Highlights: → We study the effect of Ni pollution on photosynthesis and isoprenoid emissions. → Ni stress significantly decreases photosynthesis. The main limitations are attributed to mesophyll conductance and metabolism impairment. → Constitutive isoprene emission was significantly stimulated in Ni-stressed leaves. Exposure to enhanced Ni concentration induces cis-beta-ocimene and linalool emissions. - The study reveals consequences of Ni stress on plant physiology, namely increasing diffusional limitation to photosynthesis and isoprenoid emissions.

Minutes of the IFMIF technical meeting

International Nuclear Information System (INIS)

Nakamura, H.; Takeda, M.; Ida, M.; Maebara, S.; Yutani, T.; Sugimoto, M.

2004-03-01

The IFMIF Technical Meeting was held on December 4-5, 2003 at Shiran-kaikan, Kyoto University. The main objectives are 1) to finalize the Comprehensive Design Report (CDR), 2) to discuss IFMIF cost and organization, 3) to review technical status of major systems, transition phase activities and EVEDA plan. This report presents a brief summary of the results of the meeting. Agenda, participants list and presentation materials are attached as Appendix. (author)

Establishment of the International Power Institute. Final technical report

Energy Technology Data Exchange (ETDEWEB)

Julius E. Coles

2000-08-04

The International Power Institute, in collaboration with American industries, seeks to address technical, political, economic and cultural issues of developing countries in the interest of facilitating profitable transactions in power related infrastructure projects. IPI works with universities, governments and commercial organizations to render project-specific recommendations for private-sector investment considerations. IPI also established the following goals: Facilitate electric power infrastructure transactions between developing countries and the US power industry; Collaborate with developing countries to identify development strategies to achieve energy stability; and Encourage market driven solutions and work collaboratively with other international trade energy, technology and banking organizations.

A photosynthesis-based two-leaf canopy stomatal ...

Science.gov (United States)

A coupled photosynthesis-stomatal conductance model with single-layer sunlit and shaded leaf canopy scaling is implemented and evaluated in a diagnostic box model with the Pleim-Xiu land surface model (PX LSM) and ozone deposition model components taken directly from the meteorology and air quality modeling system—WRF/CMAQ (Weather Research and Forecast model and Community Multiscale Air Quality model). The photosynthesis-based model for PX LSM (PX PSN) is evaluated at a FLUXNET site for implementation against different parameterizations and the current PX LSM approach with a simple Jarvis function (PX Jarvis). Latent heat flux (LH) from PX PSN is further evaluated at five FLUXNET sites with different vegetation types and landscape characteristics. Simulated ozone deposition and flux from PX PSN are evaluated at one of the sites with ozone flux measurements. Overall, the PX PSN simulates LH as well as the PX Jarvis approach. The PX PSN, however, shows distinct advantages over the PX Jarvis approach for grassland that likely result from its treatment of C3 and C4 plants for CO2 assimilation. Simulations using Moderate Resolution Imaging Spectroradiometer (MODIS) leaf area index (LAI) rather than LAI measured at each site assess how the model would perform with grid averaged data used in WRF/CMAQ. MODIS LAI estimates degrade model performance at all sites but one site having exceptionally old and tall trees. Ozone deposition velocity and ozone flux along with LH

Effect of Zinc Deficiency and Excess on the Growth and Photosynthesis of Winter Wheat

Directory of Open Access Journals (Sweden)

N.M. Kaznina

2017-12-01

Full Text Available Zinc is one of the necessary micronutrients for plants, which performs a number of various functions in their cells. Therefore, the deficiency of this element negatively affects on plants and leads to a significant decrease of their productivity. On the other hand, zinc in high concentrations is toxic to plants, and its accumulation in aerial organs, especially in cereals, represent a real danger to human and animal health. In this investigation the effect of the deficiency (Zn 0 μM and the excess of zinc (Zn 1000 μM on the growth and photosynthesis of the winter wheat (cv. Mironovskaya 39 was studied. As a result, similarities and differences in the response of plants to these two types of stress were revealed. In particular, both with a lack and with an excess of metal in the nutrient solution, shoot growth and photosynthesis rate are inhibited which leads to a decrease in the accumulation of dry biomass. Excess of metal, in contrast to its deficiency, leads to inhibition of root growth, and also a negative impact on pigment content, including light-harvesting complexes, and on maximum quantum yield of PS II. It is assumed that these changes in the photosynthetic apparatus are the main causes of a decrease of photosynthesis rate in plants under these conditions, whereas in the case of zinc deficiency, an inhibition of the process intensity is most likely due to a change in the activity of zinc-containing enzymes involved in the dark reactions of photosynthesis.

High tracking resolution detectors. Final Technical Report

International Nuclear Information System (INIS)

Vasile, Stefan; Li, Zheng

2010-01-01

High-resolution tracking detectors based on Active Pixel Sensor (APS) have been valuable tools in Nuclear Physics and High-Energy Physics research, and have contributed to major discoveries. Their integration time, radiation length and readout rate is a limiting factor for the planed luminosity upgrades in nuclear and high-energy physics collider-based experiments. The goal of this program was to demonstrate and develop high-gain, high-resolution tracking detector arrays with faster readout, and shorter radiation length than APS arrays. These arrays may operate as direct charged particle detectors or as readouts of high resolution scintillating fiber arrays. During this program, we developed in CMOS large, high-resolution pixel sensor arrays with integrated readout, and reset at pixel level. Their intrinsic gain, high immunity to surface and moisture damage, will allow operating these detectors with minimal packaging/passivation requirements and will result in radiation length superior to APS. In Phase I, we designed and fabricated arrays with calorimetric output capable of sub-pixel resolution and sub-microsecond readout rate. The technical effort was dedicated to detector and readout structure development, performance verification, as well as to radiation damage and damage annealing.

Limitations to soybean photosynthesis at elevated carbon dioxide in free-air enrichment and open top chamber systems.

Science.gov (United States)

Bunce, James A

2014-09-01

It has been suggested that the stimulation of soybean photosynthesis by elevated CO2 was less in free-air carbon dioxide enrichment (FACE) systems than in open top chambers (OTC), which might explain smaller yield increases at elevated CO2 in FACE systems. However, this has not been tested using the same cultivars grown in the same location. I tested whether soybean photosynthesis at high light and elevated CO2 (ambient+180 μmol mol(-1)) was limited by electron transport (J) in FACE systems but by ribulose-bisphosphate carboxylation capacity (VCmax) in OTC. FACE systems with daytime and continuous CO2 enrichment were also compared. The results indicated that in both cultivars examined, midday photosynthesis at high light was always limited by VCmax, both in the FACE and in the OTC systems. Daytime only CO2 enrichment did not affect photosynthetic parameters or limitations, but did result in significantly smaller yields in both cultivars than continuous elevation. Photosynthesis measured at low photosynthetic photon flux density (PPFD) was not higher at elevated than at ambient CO2, because of an acclimation to elevated CO2 which was only evident at low measurement PPFDs. Published by Elsevier Ireland Ltd.

International conference on "Photosynthesis research for sustainability-2013: in honor of Jalal A. Aliyev", held during June 5-9, 2013, Baku, Azerbaijan.

Science.gov (United States)

Allakhverdiev, Suleyman I; Huseynova, Irada M; Govindjee

2013-12-01

In this brief report, we provide a pictorial essay on an international conference "Photosynthesis Research for Sustainability-2013 in honor of Jalal A. Aliyev" that was held in Baku, Azerbaijan, during June 5-9, 2013 ( http://photosynthesis2013.cellreg.org/ ). We begin this report with a brief note on Jalal Aliyev, the honored scientist, and on John Walker (1997 Nobel laureate in Chemistry) who was a distinguished guest and lecturer at the Conference. We briefly describe the Conference, and the program. In addition to the excellent scientific program, a special feature of the Conference was the presentation of awards to nine outstanding young investigators; they are recognized in this report. We have also included several photographs to show the pleasant ambience at this conference. (See http://photosynthesis2013.cellreg.org/Photo-Gallery.php ; https://www.dropbox.com/sh/qcr124dajwffwh6/TlcHBvFu4H?m ; and https://www.copy.com/s/UDlxb9fgFXG9/Baku for more photographs taken by the authors as well as by others.) We invite the readers to the next conferences on "Photosynthesis Research for Sustainability-2014: in honor of Vladimir A. Shuvalov" to be held during June 2-7, 2014, in Pushchino, Russia. Detailed information for this will be posted at the Website: http://photosynthesis2014.cellreg.org/ , and for the subsequent conference on "Photosynthesis Research for Sustainability-2015" to be held in May or June 2015, in Baku, Azerbaijan, at http://photosynthesis2015.cellreg.org/ .

Expectation and task for constructing the volume reduction system of removed soils. In search of the technical integrity from the intermediate storage to final disposal

International Nuclear Information System (INIS)

Mori, Hisaki

2016-01-01

The intermediate storage volume of the removed soils and incineration ash in Fukushima is supposed about 22 million cubic meters. Within 30 years after starting the intermediate storage, the final disposal outside Fukushima prefecture to these removed soils and incineration ash is determined by the law. Because these removed soils are the very-very low radio activity, the volume reduction method is most effective to reduce the burden of the final disposal. As the volume reduction technology is the stage of research and development, the possibility of the introduction of the volume reduction technology that has the consistency of the final disposal technology is evaluated from the point of view of cost. Since this business is accompanied by economic and technical risk to implement private companies, this project is considered appropriate to be implemented as a national project. (author)

Scalable data management, analysis and visualization (SDAV) Institute. Final Scientific/Technical Report

Energy Technology Data Exchange (ETDEWEB)

Geveci, Berk [Kitware, Inc., Clifton Park, NY (United States)

2017-03-28

The purpose of the SDAV institute is to provide tools and expertise in scientific data management, analysis, and visualization to DOE’s application scientists. Our goal is to actively work with application teams to assist them in achieving breakthrough science, and to provide technical solutions in the data management, analysis, and visualization regimes that are broadly used by the computational science community. Over the last 5 years members of our institute worked directly with application scientists and DOE leadership-class facilities to assist them by applying the best tools and technologies at our disposal. We also enhanced our tools based on input from scientists on their needs. Many of the applications we have been working with are based on connections with scientists established in previous years. However, we contacted additional scientists though our outreach activities, as well as engaging application teams running on leading DOE computing systems. Our approach is to employ an evolutionary development and deployment process: first considering the application of existing tools, followed by the customization necessary for each particular application, and then the deployment in real frameworks and infrastructures. The institute is organized into three areas, each with area leaders, who keep track of progress, engagement of application scientists, and results. The areas are: (1) Data Management, (2) Data Analysis, and (3) Visualization. Kitware has been involved in the Visualization area. This report covers Kitware’s contributions over the last 5 years (February 2012 – February 2017). For details on the work performed by the SDAV institute as a whole, please see the SDAV final report.

The Path of Carbon in Photosynthesis XIV.

Science.gov (United States)

Calvin, Melvin; Bassham, J. A.; Benson, A. A.; Kawaguchi, S.; Lynch, V. H.; Stepka, W.; Tolbert, N. E.

1951-06-30

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.

The Path of Carbon in Photosynthesis. XIV.

Energy Technology Data Exchange (ETDEWEB)

Calvin, Melvin; Bassham, J.A.; Benson, A.A.; Kawaguchi, S.; Lynch, V.H.; Stepka, W.; Tolbert, N.E.

1951-06-30

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.

Engineering photosynthesis in plants and synthetic microorganisms.

Science.gov (United States)

Maurino, Veronica G; Weber, Andreas P M

2013-01-01

Photosynthetic organisms, such as cyanobacteria, algae, and plants, sustain life on earth by converting light energy, water, and CO(2) into chemical energy. However, due to global change and a growing human population, arable land is becoming scarce and resources, including water and fertilizers, are becoming exhausted. It will therefore be crucial to design innovative strategies for sustainable plant production to maintain the food and energy bases of human civilization. Several different strategies for engineering improved photosynthesis in crop plants and introducing novel photosynthetic capacity into microorganisms have been reviewed.

Path of Carbon in Photosynthesis III.

Science.gov (United States)

Benson, A. A.; Calvin, M.

1948-06-01

Although the overall reaction of photosynthesis can be specified with some degree of certainty (CO{sub 2} + H{sub 2}O + light {yields} sugars + possibly other reduced substances), the intermediates through which the carbon passes during the course of this reduction have, until now, been largely a matter of conjecture. The availability of isotopic carbon, that is, a method of labeling the carbon dioxide, provides the possibility of some very direct experiments designed to recognize these intermediates and, perhaps, help to understand the complex sequence and interplay of reactions which must constitute the photochemical process itself. The general design of such experiments is an obvious one, namely the exposure of the green plant to radioactive carbon dioxide and light under a variety of conditions and for continually decreasing lengths of time, followed by the identification of the compounds into which the radioactive carbon is incorporated under each condition and time period. From such data it is clear that in principle, at least, it should be possible to establish the sequence of compounds in time through which the carbon passes on its path from carbon dioxide to the final products. In the course of shortening the photosynthetic times, one times, one ultimately arrives at the condition of exposing the plants to the radioactive carbon dioxide with a zero illumination time, that is, in the dark. Actually, in the work the systematic order of events was reversed, and they have begun by studying first the dark fixation and then the shorter photosynthetic times. The results of the beginnings of this sort of a systematic investigation are given in Table I which includes three sets of experiments, namely a dark fixation experiment and two photosynthetic experiments, one of 30 seconds duration and the other of 60 seconds duration.

Medicare and Medicaid programs; salary equivalency guidelines for physical therapy, respiratory therapy, speech language pathology, and occupational therapy services; revised effective date and technical correction--HCFA. Final rule; delay of effective date and correction.

Science.gov (United States)

1998-03-31

This document delays the effective date of the final rule on salary equivalency guidelines, published in the Federal Register (63 FR 5106) on January 30, 1998, from April 1, 1998 to April 10, 1998. In addition, we are making a technical correction in the preamble to the January 30, 1998 final rule.

Structure-based optics of centric diatom frustules: modulation of the in vivo light field for efficient diatom photosynthesis.

Science.gov (United States)

Goessling, Johannes W; Su, Yanyan; Cartaxana, Paulo; Maibohm, Christian; Rickelt, Lars F; Trampe, Erik C L; Walby, Sandra L; Wangpraseurt, Daniel; Wu, Xia; Ellegaard, Marianne; Kühl, Michael

2018-07-01

The optical properties of diatom silicate frustules inspire photonics and nanotechnology research. Whether light interaction with the nano-structure of the frustule also affects diatom photosynthesis has remained unclear due to lack of information on frustule optical properties under more natural conditions. Here we demonstrate that the optical properties of the frustule valves in water affect light harvesting and photosynthesis in live cells of centric diatoms (Coscinodiscus granii). Microscale cellular mapping of photosynthesis around localized spot illumination demonstrated optical coupling of chloroplasts to the valve wall. Photonic structures of the three-layered C. granii valve facilitated light redistribution and efficient photosynthesis in cell regions distant from the directly illuminated area. The different porous structure of the two sides of the valve exhibited photon trapping and forward scattering of blue light enhancing photosynthetic active radiation inside the cell. Photonic structures of diatom frustules thus alter the cellular light field with implications on diatom photobiology. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

A photocatalyst-enzyme coupled artificial photosynthesis system for solar energy in production of formic acid from CO2.

Science.gov (United States)

Yadav, Rajesh K; Baeg, Jin-Ook; Oh, Gyu Hwan; Park, No-Joong; Kong, Ki-jeong; Kim, Jinheung; Hwang, Dong Won; Biswas, Soumya K

2012-07-18

The photocatalyst-enzyme coupled system for artificial photosynthesis process is one of the most promising methods of solar energy conversion for the synthesis of organic chemicals or fuel. Here we report the synthesis of a novel graphene-based visible light active photocatalyst which covalently bonded the chromophore, such as multianthraquinone substituted porphyrin with the chemically converted graphene as a photocatalyst of the artificial photosynthesis system for an efficient photosynthetic production of formic acid from CO(2). The results not only show a benchmark example of the graphene-based material used as a photocatalyst in general artificial photosynthesis but also the benchmark example of the selective production system of solar chemicals/solar fuel directly from CO(2).

Chloroplast Dynamics and Photosynthetic Efficiency: Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Hanson, Maureen [Cornell Univ., Ithaca, NY (United States)

2016-11-03

This project investigated the mechanism by which chloroplasts position themselves to maximize solar energy utilization, to enhance gas exchange, to minimize environmental stress, and to promote efficient exchange of metabolites with other compartments within the plant cell. Chloroplasts move within leaf cells to optimize light levels, moving toward levels of light useful for photosynthesis while moving away from excess light. Plastids sometimes extend their reach by sending out projections (stromules) that can connect anchor chloroplasts in position within the cell or provide close contacts with plasma membrane, mitochondria, peroxisomes, endoplasmic reticulum, and the nucleus. The intracellular location of chloroplasts in relation to other organelles with which they share biosynthetic pathways, such as peroxisomes and mitochondria in photorespiration, affects metabolite flow. This work contributed to the knowledge of the mechanisms of organelle movement and anchoring in specific locations in plant cells and how proteins traffic within the cell. We identified two domains on 12 of the 13 Arabidopsis myosins that were similar to the vacuole-binding (V) domain characterized in yeast and to the DIL domain characterized in yeast and mouse as required for secretory vesicle or melanosome movement, respectively. Because all of the Arabidopsis regions with homology to the V domain contain the amino acid sequence PAL, we refer to this region as the Arabidopsis PAL domain. We have used the yeast Myo2p tail structural information to model the 12 myosin XI tail domains containing the homologous PAL and DIL domains. Eight YFP::DIL domain fusions labeled peroxisomes; none labeled mitochondria or chloroplasts. Six myosin XI Vacuole domains labeled mitochondria and seven labeled Golgi bodies. The Arabidopsis myosin XI-F PAL domain and the homologous myosin XI-F PAL domain from N. benthamiana labels chloroplasts and stromules in N. benthamiana leaves. Using an Arabidopsis line

Summary of the ITER final design report. July 2001

International Nuclear Information System (INIS)

2001-01-01

This document is a summary of the ITER final design report foreseen during the current, Engineering Design Activities (EDA), phase of the ITER project. The report presents the results of collaborative design and supporting technical work undertaken by the ITER Joint Central team (JCT) and the Home Teams (HT) of the parties to the agreement on co-operation in the Engineering Design Activities for ITER (the ITER EDA Agreement). This report marks the achievement of the full technical scope of activities indicated in the ITER EDA Agreement, with a final design which meets the programmatic objective defined in the Agreement and satisfies detailed scientific, technical and costing objectives set by ITER Council in 1998

New usable technical specifications

International Nuclear Information System (INIS)

Webster, S.A.; Tomasi, L.T.; Bernier, R.A.

1989-01-01

After 2 yr of preparation, 1988 finally saw the nuclear industry writing operator-oriented technical specifications. This effort is a continuation of previous efforts to develop improved and usable standard technical specifications (STSs), and is being conducted by the four nuclear steam supply system vendor owners' groups under the auspices of the Nuclear Management Resources Council. Each participant is currently preparing a set of improved STSs based on a writer's guide that was developed through a combined industry effort. In May of 1987, a Human Factors Improvements to Technical Specifications (HFITS) task group was formed to prepare a writer's guide for improved, industrywide STSs. This task group was composed of two representatives from each owners' group, one with a human factors background and one with some operations background. Two documents were prepared in 6 months, a human factors report laying the groundwork for the considerations to go into technical specifications and a writer's guide for their preparation. This paper reports on the application of this writer's guide to the writing of improved STS

Light distribution in leaf chambers and its consequences for photosynthesis measurements

NARCIS (Netherlands)

Hogewoning, S.W.; Trouwborst, G.; Harbinson, J.; Ieperen, van W.

2010-01-01

The impact of a heterogeneous distribution of actinic light within a leaf chamber for photosynthetic measurements by gas exchange on the photosynthesis-irradiance relationship was investigated. High-resolution light distributions were measured over the area of a commercially available clamp-on leaf

Aquatic CAM photosynthesis: a brief history of its discovery

Science.gov (United States)

Keeley, Jon E.

2014-01-01

Aquatic CAM (Crassulacean Acid Metabolism) photosynthesis was discovered while investigating an unrelated biochemical pathway concerned with anaerobic metabolism. George Bowes was a significant contributor to this project early in its infancy. Not only did he provide me with some valuable perspectives on peer review rejections, but by working with his gas exchange system I was able to take our initial observations of diel fluctuations in malic acid to the next level, showing this aquatic plant exhibited dark CO2 uptake. CAM is universal in all aquatic species of the worldwide Lycophyta genus Isoetes and non-existent in terrestrial Isoetes. Outside of this genus aquatic CAM has a limited occurrence in three other families, including the Crassulaceae. This discovery led to fascinating adventures in the highlands of the Peruvian Andes in search of Stylites, a terrestrial relative of Isoetes. Stylites is a plant that is hermetically sealed from the atmosphere and obtains all of its carbon from terrestrial sources and recycles carbon through CAM. Considering the Mesozoic origin of Isoetes in shallow pools, coupled with the fact that aquatic Isoetes universally possess CAM, suggests the earliest evolution of CAM photosynthesis was most likely not in terrestrial plants.

Effects of ammonia from livestock farming on lichen photosynthesis

Energy Technology Data Exchange (ETDEWEB)

Paoli, Luca [Department of Environmental Science ' G. Sarfatti' , University of Siena, via Mattioli 4, I-53100 Siena (Italy); Department of Biology, University of Crete, 71409 Heraklion, Crete (Greece); Pirintsos, Stergios Arg.; Kotzabasis, Kiriakos [Department of Biology, University of Crete, 71409 Heraklion, Crete (Greece); Pisani, Tommaso [Department of Environmental Science ' G. Sarfatti' , University of Siena, via Mattioli 4, I-53100 Siena (Italy); Navakoudis, Eleni [Department of Biology, University of Crete, 71409 Heraklion, Crete (Greece); Loppi, Stefano, E-mail: loppi@unisi.i [Department of Environmental Science ' G. Sarfatti' , University of Siena, via Mattioli 4, I-53100 Siena (Italy)

2010-06-15

This study investigated if atmospheric ammonia (NH{sub 3}) pollution around a sheep farm influences the photosynthetic performance of the lichens Evernia prunastri and Pseudevernia furfuracea. Thalli of both species were transplanted for up to 30 days in a semi-arid region (Crete, Greece), at sites with concentrations of atmospheric ammonia of ca. 60 mug/m{sup 3} (at a sheep farm), ca. 15 mug/m{sup 3} (60 m from the sheep farm) and ca. 2 mug/m{sup 3} (a remote area 5 km away). Lichen photosynthesis was analysed by the chlorophyll a fluorescence emission to identify targets of ammonia pollution. The results indicated that the photosystem II of the two lichens exposed to NH{sub 3} is susceptible to this pollutant in the gas-phase. The parameter PI{sub ABS}, a global index of photosynthetic performance that combines in a single expression the three functional steps of the photosynthetic activity (light absorption, excitation energy trapping, and conversion of excitation energy to electron transport) was much more sensitive to NH{sub 3} than the F{sub V}/F{sub M} ratio, one of the most commonly used stress indicators. - Ammonia from livestock farming affects lichen photosynthesis.

Hydrogen production from water: Recent advances in photosynthesis research

Energy Technology Data Exchange (ETDEWEB)

Greenbaum, E.; Lee, J.W. [Oak Ridge National Lab., TN (United States). Chemical Technology Div.

1997-12-31

The great potential of hydrogen production by microalgal water splitting is predicated on quantitative measurement of the algae`s hydrogen-producing capability, which is based on the following: (1) the photosynthetic unit size of hydrogen production; (2) the turnover time of photosynthetic hydrogen production; (3) thermodynamic efficiencies of conversion of light energy into the Gibbs free energy of molecular hydrogen; (4) photosynthetic hydrogen production from sea water using marine algae; (5) the potential for research advances using modern methods of molecular biology and genetic engineering to maximize hydrogen production. ORNL has shown that sustained simultaneous photoevolution of molecular hydrogen and oxygen can be performed with mutants of the green alga Chlamydomonas reinhardtii that lack a detectable level of the Photosystem I light reaction. This result is surprising in view of the standard two-light reaction model of photosynthesis and has interesting scientific and technological implications. This ORNL discovery also has potentially important implications for maximum thermodynamic conversion efficiency of light energy into chemical energy by green plant photosynthesis. Hydrogen production performed by a single light reaction, as opposed to two, implies a doubling of the theoretically maximum thermodynamic conversion efficiency from {approx}10% to {approx}20%.

TADS Final Evaluation Report, 1980-81. Appendix S.

Science.gov (United States)

Suarez, Tanya M.; And Others

The document contains the final report of the Technical Assistance Development System (TADS), a program which provided technical assistance (TA) services to 53 Handicapped Children's Early Education Program (HCEEP) demonstration projects and 13 State Implementation Grants (SIGs). The evaluation report is divided into five sections. Section 1…

Final report. Geothermal Energy Program: Information dissemination, public outreach, and technical analysis activities. April 1, 1999 to December 31, 2001. USDOE Grant No. DE-FG01-99-EE35098

Energy Technology Data Exchange (ETDEWEB)

Lund, John W.

2002-03-22

This is the final report of the accomplishments of the geothermal energy program: information dissemination, public outreach, and technical analysis activities by the project team consisting of the Geo-Heat Center, Geothermal Resources Council, Geothermal Education Office, Geothermal Energy Association, and the Washington State University Energy Program.

Evolution of the 3-hydroxypropionate bicycle and recent transfer of anoxygenic photosynthesis into the Chloroflexi

Science.gov (United States)

Shih, Patrick M.; Ward, Lewis M.; Fischer, Woodward W.

2017-10-01

Various lines of evidence from both comparative biology and the geologic record make it clear that the biochemical machinery for anoxygenic photosynthesis was present on early Earth and provided the evolutionary stock from which oxygenic photosynthesis evolved ca. 2.3 billion years ago. However, the taxonomic identity of these early anoxygenic phototrophs is uncertain, including whether or not they remain extant. Several phototrophic bacterial clades are thought to have evolved before oxygenic photosynthesis emerged, including the Chloroflexi, a phylum common across a wide range of modern environments. Although Chloroflexi have traditionally been thought to be an ancient phototrophic lineage, genomics has revealed a much greater metabolic diversity than previously appreciated. Here, using a combination of comparative genomics and molecular clock analyses, we show that phototrophic members of the Chloroflexi phylum are not particularly ancient, having evolved well after the rise of oxygen (ca. 867 million years ago), and thus cannot be progenitors of oxygenic photosynthesis. Similarly, results show that the carbon fixation pathway that defines this clade—the 3-hydroxypropionate bicycle—evolved late in Earth history as a result of a series of horizontal gene transfer events, explaining the lack of geological evidence for this pathway based on the carbon isotope record. These results demonstrate the role of horizontal gene transfer in the recent metabolic innovations expressed within this phylum, including its importance in the development of a novel carbon fixation pathway.

Fifth technical meeting on quality

International Nuclear Information System (INIS)

Girard, A.

1998-01-01

This article reports on the 5th Technical Meeting on Quality which was held in San Diego on 20-22 October 1997 and which was attended by representatives of the Home and Joint Central Team and of manufacturers currently involved in the Large R and D projects. The meeting made progress towards the finalization of the ITER Quality Manual document for inclusion in the Final Design Report and the definition of the quality necessary for ITER procurement and construction

Sb/Mn co-doped oxyfluoride silicate glasses for potential applications in photosynthesis

Energy Technology Data Exchange (ETDEWEB)

Zhu, Chaofeng [Key Laboratory of Processing and Testing Technology of Glass & Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China); Laboratoire des Verres et Céramiques, UMR-CNRS 6226, Université de Rennes 1, Rennes 35042 (France); Zhang, Xianghua, E-mail: xiang-hua.zhang@univ-rennes1.fr [Laboratoire des Verres et Céramiques, UMR-CNRS 6226, Université de Rennes 1, Rennes 35042 (France); Ma, Hongli [Laboratoire des Verres et Céramiques, UMR-CNRS 6226, Université de Rennes 1, Rennes 35042 (France)

2016-03-15

A series of Sb/Mn co-doped oxyfluoride silicate glasses were prepared via the melt-quenching method to explore red luminescent materials for potential applications in photosynthesis of green plants, and these glasses are investigated by means of luminescence decay curves, absorption, emission, and excitation spectra. We find that the as-prepared glasses are transparent in the visible region and can emit strong red light under ultraviolet, purple, and green light excitations. Furthermore, energy transfer from Sb{sup 3+} to Mn{sup 2+} ions occurs in Sb/Mn co-doped glasses. The results demonstrate that the as-prepared Sb/Mn co-doped oxyfluoride silicate glasses may serve as a potential candidate for developing glass greenhouse, which can enhance the utilization of solar energy for the photosynthesis of the green plants.

Functional criteria for emergency response facilities. Technical report (final)

International Nuclear Information System (INIS)

1981-02-01

This report describes the facilities and systems to be used by nuclear power plant licensees to improve responses to emergency situations. The facilities include the Technical Support Center (TSC), Onsite Operational Support Center (OSC), and Nearsite Emergency Operations Facility (EOF), as well as a brief discussion of the emergency response function of the control room. The data systems described are the Safety Parameter Display System (SPDS) and Nuclear Data Link (NDL). Together, these facilities and systems make up the total Emergency Response Facilities (ERFs). Licensees should follow the guidance provided both in this report and in NUREG-0654 (FEMA-REP-1), Revision 1, for design and implementation of the ERFs

Evidence for oxygenic photosynthesis half a billion years before the Great Oxidation Event

Science.gov (United States)

Planavsky, Noah J.; Asael, Dan; Hofmann, Axel; Reinhard, Christopher T.; Lalonde, Stefan V.; Knudsen, Andrew; Wang, Xiangli; Ossa Ossa, Frantz; Pecoits, Ernesto; Smith, Albertus J. B.; Beukes, Nicolas J.; Bekker, Andrey; Johnson, Thomas M.; Konhauser, Kurt O.; Lyons, Timothy W.; Rouxel, Olivier J.

2014-04-01

The early Earth was characterized by the absence of oxygen in the ocean-atmosphere system, in contrast to the well-oxygenated conditions that prevail today. Atmospheric concentrations first rose to appreciable levels during the Great Oxidation Event, roughly 2.5-2.3 Gyr ago. The evolution of oxygenic photosynthesis is generally accepted to have been the ultimate cause of this rise, but it has proved difficult to constrain the timing of this evolutionary innovation. The oxidation of manganese in the water column requires substantial free oxygen concentrations, and thus any indication that Mn oxides were present in ancient environments would imply that oxygenic photosynthesis was ongoing. Mn oxides are not commonly preserved in ancient rocks, but there is a large fractionation of molybdenum isotopes associated with the sorption of Mo onto the Mn oxides that would be retained. Here we report Mo isotopes from rocks of the Sinqeni Formation, Pongola Supergroup, South Africa. These rocks formed no less than 2.95 Gyr ago in a nearshore setting. The Mo isotopic signature is consistent with interaction with Mn oxides. We therefore infer that oxygen produced through oxygenic photosynthesis began to accumulate in shallow marine settings at least half a billion years before the accumulation of significant levels of atmospheric oxygen.

Temporal and spatial transcriptomic and microRNA dynamics of CAM photosynthesis in pineapple.

Science.gov (United States)

Wai, Ching M; VanBuren, Robert; Zhang, Jisen; Huang, Lixian; Miao, Wenjing; Edger, Patrick P; Yim, Won C; Priest, Henry D; Meyers, Blake C; Mockler, Todd; Smith, J Andrew C; Cushman, John C; Ming, Ray

2017-10-01

The altered carbon assimilation pathway of crassulacean acid metabolism (CAM) photosynthesis results in an up to 80% higher water-use efficiency than C 3 photosynthesis in plants making it a potentially useful pathway for engineering crop plants with improved drought tolerance. Here we surveyed detailed temporal (diel time course) and spatial (across a leaf gradient) gene and microRNA (miRNA) expression patterns in the obligate CAM plant pineapple [Ananas comosus (L.) Merr.]. The high-resolution transcriptome atlas allowed us to distinguish between CAM-related and non-CAM gene copies. A differential gene co-expression network across green and white leaf diel datasets identified genes with circadian oscillation, CAM-related functions, and source-sink relations. Gene co-expression clusters containing CAM pathway genes are enriched with clock-associated cis-elements, suggesting circadian regulation of CAM. About 20% of pineapple microRNAs have diel expression patterns, with several that target key CAM-related genes. Expression and physiology data provide a model for CAM-specific carbohydrate flux and long-distance hexose transport. Together these resources provide a list of candidate genes for targeted engineering of CAM into C 3 photosynthesis crop species. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

Elevated CO2 response of photosynthesis depends on ozone concentration in aspen

Science.gov (United States)

Asko Noormets; Olevi Kull; Anu Sober; Mark E. Kubiske; David F. Karnosky

2010-01-01

The effect of elevated CO2 and O3 on apparent quantum yield (ø), maximum photosynthesis (Pmax), carboxylation efficiency (Vcmax) and electron transport capacity (Jmax) at different canopy locations was studied in two aspen (Populus...

;Evolution of Photosynthesis' (1970), re-examined thirty years later.

Science.gov (United States)

Olson, J M

2001-01-01

I have re-examined my 1970 article 'Evolution of Photosynthesis' (Olson JM, Science 168: 438-446) to see whether any of my original proposals still survive. My original conviction that the evolution of photosynthesis was intimately connected with the origin of life has been replaced with the realization that photosynthesis may have been invented by the Bacteria after their divergence from the Archea. The common ancestor of all extant photosynthetic bacteria and cyanobacteria probably contained bacteriochlorophyll a, rather than chlorophyll a as originally proposed, and may have carried out CO(2) fixation instead of photoassimilation. The first electron donors were probably reduced sulfur compounds and later ferrous iron. The common ancestor of all extant reaction centers was probably similar to the homodimeric RC1 of present-day green sulfur bacteria (Chlorobiaceae) and heliobacteria. In the common ancestor of proteobacteria and cyanobacteria, the gene for the primordial RC1 was apparently duplicated and one copy split into two genes, one for RC2 and the other for a chlorophyll protein similar to CP43 and CP47 in extant cyanobacteria and chloroplasts. Homodimeric RC1 and homodimeric RC2 functioned in series as in the Z-scheme to deliver electrons from Fe(OH)(+) to NADP(+), while RC1 and/or RC2 separately drove cyclic electron flow for the production of ATP. In the line of evolution leading to proteobacteria, RC1 and the chlorophyll protein were lost, but RC2 was retained and became heterodimeric. In the line leading to cyanobacteria, both RC1 and RC2 replaced bacteriochlorophyll a with chlorophyll a and became heterodimeric. Heterodimeric RC2 further coevolved with a Mn-containing complex to utilize water as the electron donor for CO(2) fixation. The chlorophyll-protein was also retained and evolved into CP43 and CP47. Heliobacteria are the nearest photosynthetic relatives of cyanobacteria. The branching order of photosynthetic genes appears to be (1

Geophysical Global Modeling for Extreme Crop Production Using Photosynthesis Models Coupled to Ocean SST Dipoles

Science.gov (United States)

Kaneko, D.

2016-12-01

Climate change appears to have manifested itself along with abnormal meteorological disasters. Instability caused by drought and flood disasters is producing poor harvests because of poor photosynthesis and pollination. Fluctuations of extreme phenomena are increasing rapidly because amplitudes of change are much greater than average trends. A fundamental cause of these phenomena derives from increased stored energy inside ocean waters. Geophysical and biochemical modeling of crop production can elucidate complex mechanisms under seasonal climate anomalies. The models have progressed through their combination with global climate reanalysis, environmental satellite data, and harvest data on the ground. This study examined adaptation of crop production to advancing abnormal phenomena related to global climate change. Global environmental surface conditions, i.e., vegetation, surface air temperature, and sea surface temperature observed by satellites, enable global modeling of crop production and monitoring. Basic streams of the concepts of modeling rely upon continental energy flow and carbon circulation among crop vegetation, land surface atmosphere combining energy advection from ocean surface anomalies. Global environmental surface conditions, e.g., vegetation, surface air temperature, and sea surface temperature observed by satellites, enable global modeling of crop production and monitoring. The method of validating the modeling relies upon carbon partitioning in biomass and grains through carbon flow by photosynthesis using carbon dioxide unit in photosynthesis. Results of computations done for this study show global distributions of actual evaporation, stomata opening, and photosynthesis, presenting mechanisms related to advection effects from SST anomalies in the Pacific, Atlantic, and Indian oceans on global and continental croplands. For North America, climate effects appear clearly in severe atmospheric phenomena, which have caused drought and forest fires

Far-red light is needed for efficient photochemistry and photosynthesis.

Science.gov (United States)

Zhen, Shuyang; van Iersel, Marc W

2017-02-01

The efficiency of monochromatic light to drive photosynthesis drops rapidly at wavelengths longer than 685nm. The photosynthetic efficiency of these longer wavelengths can be improved by adding shorter wavelength light, a phenomenon known as the Emerson enhancement effect. The reverse effect, the enhancement of photosynthesis under shorter wavelength light by longer wavelengths, however, has not been well studied and is often thought to be insignificant. We quantified the effect of adding far-red light (peak at 735nm) to red/blue or warm-white light on the photosynthetic efficiency of lettuce (Lactuca sativa). Adding far-red light immediately increased quantum yield of photosystem II (Φ PSII ) of lettuce by an average of 6.5 and 3.6% under red/blue and warm-white light, respectively. Similar or greater increases in Φ PSII were observed after 20min of exposure to far-red light. This longer-term effect of far-red light on Φ PSII was accompanied by a reduction in non-photochemical quenching of fluorescence (NPQ), indicating that far-red light reduced the dissipation of absorbed light as heat. The increase in Φ PSII and complementary decrease in NPQ is presumably due to preferential excitation of photosystem I (PSI) by far-red light, which leads to faster re-oxidization of the plastoquinone pool. This facilitates reopening of PSII reaction centers, enabling them to use absorbed photons more efficiently. The increase in Φ PSII by far-red light was associated with an increase in net photosynthesis (P n ). The stimulatory effect of far-red light increased asymptotically with increasing amounts of far-red. Overall, our results show that far-red light can increase the photosynthetic efficiency of shorter wavelength light that over-excites PSII. Copyright © 2016 Elsevier GmbH. All rights reserved.

Elevated ozone negatively affects photosynthesis of current-year leaves but not previous-year leaves in evergreen Cyclobalanopsis glauca seedlings

International Nuclear Information System (INIS)

Zhang, Weiwei; Feng, Zhaozhong; Wang, Xiaoke; Niu, Junfeng

2014-01-01

To assess the effects of leaf age/layer on the response of photosynthesis to chronic ozone (O 3 ), Cyclobalanopsis glauca seedlings, a dominant evergreen broadleaf tree species in sub-tropical regions, were exposed to either ambient air (AA) or elevated O 3 (AA + 60 ppb O 3 , E-O 3 ) for two growing seasons in open-top chambers. Chlorophyll content, gas exchange and chlorophyll a fluorescence were investigated three times throughout the 2nd year of O 3 exposure. Results indicated that E-O 3 decreased photosynthetic parameters, particularly light-saturated photosynthesis rate, stomatal conductance and effective quantum yield of PSII photochemistry of current-year leaves but not previous-year leaves. Stomatal conductance of plants grown under ambient conditions partially contributed to the different response to E-O 3 between leaf layers. Light radiation or other physiological and biochemical processes closely related to photosynthesis might play important roles. All suggested that leaf ages or layers should be considered when assessing O 3 risk on evergreen woody species. -- Highlights: • Response of evergreen Cyclobalanopsis glauca to O 3 was investigated. • Elevated O 3 significantly reduced photosynthesis of current-year leaves. • Previous-year leaves showed little response to O 3 . • Stomatal conductance contributes to the response difference to O 3 among leaf ages. -- Impacts of elevated O 3 on photosynthesis of evergreen woody species depend on leaf ages

Impact of elevated CO2 concentration on dynamics of leaf photosynthesis in Fagus sylvatica is modulated by sky conditions

International Nuclear Information System (INIS)

Urban, Otmar; Klem, Karel; Holišová, Petra; Šigut, Ladislav; Šprtová, Mirka; Teslová-Navrátilová, Petra; Zitová, Martina; Špunda, Vladimír; Marek, Michal V.; Grace, John

2014-01-01

It has been suggested that atmospheric CO 2 concentration and frequency of cloud cover will increase in future. It remains unclear, however, how elevated CO 2 influences photosynthesis under complex clear versus cloudy sky conditions. Accordingly, diurnal changes in photosynthetic responses among beech trees grown at ambient (AC) and doubled (EC) CO 2 concentrations were studied under contrasting sky conditions. EC stimulated the daily sum of fixed CO 2 and light use efficiency under clear sky. Meanwhile, both these parameters were reduced under cloudy sky as compared with AC treatment. Reduction in photosynthesis rate under cloudy sky was particularly associated with EC-stimulated, xanthophyll-dependent thermal dissipation of absorbed light energy. Under clear sky, a pronounced afternoon depression of CO 2 assimilation rate was found in sun-adapted leaves under EC compared with AC conditions. This was caused in particular by stomata closure mediated by vapour pressure deficit. -- Highlights: • Sky conditions affect the relative impact of elevated CO 2 on photosynthesis. • Cloudy skies reduce light use efficiency and carbon gain when CO 2 is elevated. • Stimulation of photosynthesis by high CO 2 may decline with increasing cloud cover. • High CO 2 leads to marked afternoon photosynthesis depression in sun-adapted leaves. -- The stimulatory effect of elevated CO 2 concentration on photosynthetic carbon assimilation can be expected to diminish as cloud cover increases