WorldWideScience

Sample records for globally significant photosynthetic

  1. Transcriptome analysis of functional differentiation between haploid and diploid cells of Emiliania huxleyi, a globally significant photosynthetic calcifying cell

    Science.gov (United States)

    2009-01-01

    Background Eukaryotes are classified as either haplontic, diplontic, or haplo-diplontic, depending on which ploidy levels undergo mitotic cell division in the life cycle. Emiliania huxleyi is one of the most abundant phytoplankton species in the ocean, playing an important role in global carbon fluxes, and represents haptophytes, an enigmatic group of unicellular organisms that diverged early in eukaryotic evolution. This species is haplo-diplontic. Little is known about the haploid cells, but they have been hypothesized to allow persistence of the species between the yearly blooms of diploid cells. We sequenced over 38,000 expressed sequence tags from haploid and diploid E. huxleyi normalized cDNA libraries to identify genes involved in important processes specific to each life phase (2N calcification or 1N motility), and to better understand the haploid phase of this prominent haplo-diplontic organism. Results The haploid and diploid transcriptomes showed a dramatic differentiation, with approximately 20% greater transcriptome richness in diploid cells than in haploid cells and only ≤ 50% of transcripts estimated to be common between the two phases. The major functional category of transcripts differentiating haploids included signal transduction and motility genes. Diploid-specific transcripts included Ca2+, H+, and HCO3- pumps. Potential factors differentiating the transcriptomes included haploid-specific Myb transcription factor homologs and an unusual diploid-specific histone H4 homolog. Conclusions This study permitted the identification of genes likely involved in diploid-specific biomineralization, haploid-specific motility, and transcriptional control. Greater transcriptome richness in diploid cells suggests they may be more versatile for exploiting a diversity of rich environments whereas haploid cells are intrinsically more streamlined. PMID:19832986

  2. Constrained parameterisation of photosynthetic capacity causes significant increase of modelled tropical vegetation surface temperature

    Science.gov (United States)

    Kattge, J.; Knorr, W.; Raddatz, T.; Wirth, C.

    2009-04-01

    Photosynthetic capacity is one of the most sensitive parameters of terrestrial biosphere models whose representation in global scale simulations has been severely hampered by a lack of systematic analyses using a sufficiently broad database. Due to its coupling to stomatal conductance changes in the parameterisation of photosynthetic capacity may potentially influence transpiration rates and vegetation surface temperature. Here, we provide a constrained parameterisation of photosynthetic capacity for different plant functional types in the context of the photosynthesis model proposed by Farquhar et al. (1980), based on a comprehensive compilation of leaf photosynthesis rates and leaf nitrogen content. Mean values of photosynthetic capacity were implemented into the coupled climate-vegetation model ECHAM5/JSBACH and modelled gross primary production (GPP) is compared to a compilation of independent observations on stand scale. Compared to the current standard parameterisation the root-mean-squared difference between modelled and observed GPP is substantially reduced for almost all PFTs by the new parameterisation of photosynthetic capacity. We find a systematic depression of NUE (photosynthetic capacity divided by leaf nitrogen content) on certain tropical soils that are known to be deficient in phosphorus. Photosynthetic capacity of tropical trees derived by this study is substantially lower than standard estimates currently used in terrestrial biosphere models. This causes a decrease of modelled GPP while it significantly increases modelled tropical vegetation surface temperatures, up to 0.8°C. These results emphasise the importance of a constrained parameterisation of photosynthetic capacity not only for the carbon cycle, but also for the climate system.

  3. A Global Data Set of Leaf Photosynthetic Rates, Leaf N and P, and Specific Leaf Area

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This global data set of photosynthetic rates and leaf nutrient traits was compiled from a comprehensive literature review. It includes estimates of Vcmax...

  4. A Global Data Set of Leaf Photosynthetic Rates, Leaf N and P, and Specific Leaf Area

    Data.gov (United States)

    National Aeronautics and Space Administration — This global data set of photosynthetic rates and leaf nutrient traits was compiled from a comprehensive literature review. It includes estimates of Vcmax (maximum...

  5. Introducing extra NADPH consumption ability significantly increases the photosynthetic efficiency and biomass production of cyanobacteria.

    Science.gov (United States)

    Zhou, Jie; Zhang, Fuliang; Meng, Hengkai; Zhang, Yanping; Li, Yin

    2016-11-01

    Increasing photosynthetic efficiency is crucial to increasing biomass production to meet the growing demands for food and energy. Previous theoretical arithmetic analysis suggests that the light reactions and dark reactions are imperfectly coupled due to shortage of ATP supply, or accumulation of NADPH. Here we hypothesized that solely increasing NADPH consumption might improve the coupling of light reactions and dark reactions, thereby increasing the photosynthetic efficiency and biomass production. To test this hypothesis, an NADPH consumption pathway was constructed in cyanobacterium Synechocystis sp. PCC 6803. The resulting extra NADPH-consuming mutant grew much faster and achieved a higher biomass concentration. Analyses of photosynthesis characteristics showed the activities of photosystem II and photosystem I and the light saturation point of the NADPH-consuming mutant all significantly increased. Thus, we demonstrated that introducing extra NADPH consumption ability is a promising strategy to increase photosynthetic efficiency and to enable utilization of high-intensity lights. Copyright © 2016 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  6. Seasonal variation of photosynthetic model parameters and leaf area index from global Fluxnet eddy covariance data

    NARCIS (Netherlands)

    Groenendijk, M.; Dolman, A.J.; Ammann, C.; Arneth, A.; Cescatti, A.; Molen, van der M.K.; Moors, E.J.

    2011-01-01

    Global vegetation models require the photosynthetic parameters, maximum carboxylation capacity (Vcm), and quantum yield (a) to parameterize their plant functional types (PFTs). The purpose of this work is to determine how much the scaling of the parameters from leaf to ecosystem level through a

  7. Mycotoxins: significance to global economics and health

    Science.gov (United States)

    Mycotoxins are fungal metabolites produced my micro-fungi (molds and mildews) that have significant impacts on global economics and health. Some of these metabolites are beneficial, but most are harmful and have been associated with well-known epidemics dating back to medieval times. The terms ‘myco...

  8. Regional and global significance of nuclear energy

    International Nuclear Information System (INIS)

    Schilling, H.D.

    1995-01-01

    Measures to combat poverty and improve the standard of living in countries of the Third World will inevitably boost global demand for energy, and energy conservation measures will not be able to offset this increase. Nuclear energy will regain significance in the framework of approaches adopted to resolve the energy problem, which primarily is an ecologic problem created by an extremely large flow of materials. The extraordinarily high energy density of nuclear fuels can contribute to markedly reduce the flow of materials; and at that, electric energy is an efficient substitute for primary energy forms. Thus nuclear electricity generation is of double benefit to the ecology. Engineering goals in nuclear technology thus gain a service aspect, with progress in power plant engineering and design aiming not only at enhanced engineered safety, but also at regaining public acceptance of and confidence in nuclear power plant technology. (orig./UA) [de

  9. Sustainable fuel, food, fertilizer and ecosystems through a global artificial photosynthetic system: overcoming anticompetitive barriers

    Science.gov (United States)

    Bruce, Alex; Faunce, Thomas

    2015-01-01

    This article discusses challenges that artificial photosynthetic (AP) systems will face when entering and competing in a global market characterized by established fossil fuel technology. It provides a perspective on the neoliberal principles underpinning much policy entrenching such environmentally destructive technology and outlines how competition law could aid overcoming these hurdles for AP development. In particular, it critiques the potential for competition law to promote a global AP initiative with greater emphasis on atmospheric carbon dioxide and nitrogen fixation (as well as solar-driven water splitting) to produce an equitable, globally distributed source of human food, fertilizer and biosphere sustainability, as well as hydrogen-based fuel. Some relevant strategies of competition law evaluated in this context include greater citizen–consumer involvement in shaping market values, legal requirements to factor services from the natural environment (i.e. provision of clean air, water, soil pollution degradation) into corporate costs, reform of corporate taxation and requirements to balance maximization of shareholder profit with contribution to a nominated public good, a global financial transactions tax, as well as prohibiting horizontal cartels, vertical agreements and unilateral misuse of market power. PMID:26052427

  10. Sustainable fuel, food, fertilizer and ecosystems through a global artificial photosynthetic system: overcoming anticompetitive barriers.

    Science.gov (United States)

    Bruce, Alex; Faunce, Thomas

    2015-06-06

    This article discusses challenges that artificial photosynthetic (AP) systems will face when entering and competing in a global market characterized by established fossil fuel technology. It provides a perspective on the neoliberal principles underpinning much policy entrenching such environmentally destructive technology and outlines how competition law could aid overcoming these hurdles for AP development. In particular, it critiques the potential for competition law to promote a global AP initiative with greater emphasis on atmospheric carbon dioxide and nitrogen fixation (as well as solar-driven water splitting) to produce an equitable, globally distributed source of human food, fertilizer and biosphere sustainability, as well as hydrogen-based fuel. Some relevant strategies of competition law evaluated in this context include greater citizen-consumer involvement in shaping market values, legal requirements to factor services from the natural environment (i.e. provision of clean air, water, soil pollution degradation) into corporate costs, reform of corporate taxation and requirements to balance maximization of shareholder profit with contribution to a nominated public good, a global financial transactions tax, as well as prohibiting horizontal cartels, vertical agreements and unilateral misuse of market power.

  11. Global warming: the significance of methane

    International Nuclear Information System (INIS)

    Dessus, B.; Le Treut, H.; Laponche, B.

    2008-01-01

    the concept of Global Warming Potential (GWP) indicates the relative contribution to global warming over a given period (for example 100 years) of a pulse emission at the start of the period of 1 kg of a specific greenhouse gas (GHG) in comparison to the contribution, over the same period, of an emission of 1 kg of CO 2 . The GWPs calculated for different time intervals take into account the differences in atmospheric lifetimes of the different GHGs. Using the '100-year GWP' to measure non CO 2 GHG emissions is not well suited to the case of permanent or long lifetime measures whose effectiveness is to be assessed at a given time horizon. In this context, it contributes to significantly playing down the importance of reducing emissions of GHGs with short atmospheric lifetimes. Thus, for example, methane which is not emitted over the period 2020- 2100 as a result of a landfill site being closed in 2020 will have an impact (as opposed to if the site remained in operation) that would be far greater towards 2100 compared to a CO 2 emission source that has also been stopped permanently and whose climate impact is measured in an equivalent manner. Using the GWP is only appropriate if applied year after year to time horizons considered to be of concern or decisive by climate studies, thus in particular 2050, 2100 and 2150. This is all the more significant as climate experts' current concerns lead them not only to advocate long-term stabilisation of GHG concentrations but also to avoid as far as possible intermediate excess of these concentrations over the coming century. Finally, it is noted that CH 4 prevention policies implemented in the short term may continue to have a long-term impact greater than merely taking into account the current GWP would imply. To more or less ignore the impact of CH 4 as it is unsuitable for accounting purposes affects the exclusive character of the link that may exist between the issue of GHGs and that of energy. Furthermore, if the

  12. Seasonal variation of photosynthetic model parameters and leaf area index from global Fluxnet eddy covariance data

    Science.gov (United States)

    Groenendijk, M.; Dolman, A. J.; Ammann, C.; Arneth, A.; Cescatti, A.; Dragoni, D.; Gash, J. H. C.; Gianelle, D.; Gioli, B.; Kiely, G.; Knohl, A.; Law, B. E.; Lund, M.; Marcolla, B.; van der Molen, M. K.; Montagnani, L.; Moors, E.; Richardson, A. D.; Roupsard, O.; Verbeeck, H.; Wohlfahrt, G.

    2011-12-01

    Global vegetation models require the photosynthetic parameters, maximum carboxylation capacity (Vcm), and quantum yield (α) to parameterize their plant functional types (PFTs). The purpose of this work is to determine how much the scaling of the parameters from leaf to ecosystem level through a seasonally varying leaf area index (LAI) explains the parameter variation within and between PFTs. Using Fluxnet data, we simulate a seasonally variable LAIF for a large range of sites, comparable to the LAIM derived from MODIS. There are discrepancies when LAIF reach zero levels and LAIM still provides a small positive value. We find that temperature is the most common constraint for LAIF in 55% of the simulations, while global radiation and vapor pressure deficit are the key constraints for 18% and 27% of the simulations, respectively, while large differences in this forcing still exist when looking at specific PFTs. Despite these differences, the annual photosynthesis simulations are comparable when using LAIF or LAIM (r2 = 0.89). We investigated further the seasonal variation of ecosystem-scale parameters derived with LAIF. Vcm has the largest seasonal variation. This holds for all vegetation types and climates. The parameter α is less variable. By including ecosystem-scale parameter seasonality we can explain a considerable part of the ecosystem-scale parameter variation between PFTs. The remaining unexplained leaf-scale PFT variation still needs further work, including elucidating the precise role of leaf and soil level nitrogen.

  13. Photosynthetically Available Radiation, Aqua MODIS, NPP, 0.05 degrees, Global, Science Quality

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures photosynthetically available radiation that may be used to mode primary productivity. THIS IS AN EXPERIMENTAL PRODUCT: intended strictly for...

  14. Modeling the relationship between photosynthetically active radiation and global horizontal irradiance using singular spectrum analysis

    International Nuclear Information System (INIS)

    Zempila, Melina-Maria; Taylor, Michael; Bais, Alkiviadis; Kazadzis, Stelios

    2016-01-01

    We report on the construction of generic models to calculate photosynthetically active radiation (PAR) from global horizontal irradiance (GHI), and vice versa. Our study took place at stations of the Greek UV network (UVNET) and the Hellenic solar energy network (HNSE) with measurements from NILU-UV multi-filter radiometers and CM pyranometers, chosen due to their long (≈1 M record/site) high temporal resolution (≈1 min) record that captures a broad range of atmospheric environments and cloudiness conditions. The uncertainty of the PAR measurements is quantified to be ±6.5% while the uncertainty involved in GHI measurements is up to ≈±7% according to the manufacturer. We show how multi-linear regression and nonlinear neural network (NN) models, trained at a calibration site (Thessaloniki) can be made generic provided that the input–output time series are processed with multi-channel singular spectrum analysis (M-SSA). Without M-SSA, both linear and nonlinear models perform well only locally. M-SSA with 50 time-lags is found to be sufficient for identification of trend, periodic and noise components in aerosol, cloud parameters and irradiance, and to construct regularized noise models of PAR from GHI irradiances. Reconstructed PAR and GHI time series capture ≈95% of the variance of the cross-validated target measurements and have median absolute percentage errors <2%. The intra-site median absolute error of M-SSA processed models were ≈8.2±1.7 W/m"2 for PAR and ≈9.2±4.2 W/m"2 for GHI. When applying the models trained at Thessaloniki to other stations, the average absolute mean bias between the model estimates and measured values was found to be ≈1.2 W/m"2 for PAR and ≈0.8 W/m"2 for GHI. For the models, percentage errors are well within the uncertainty of the measurements at all sites. Generic NN models were found to perform marginally better than their linear counterparts. - Highlights: • Generic linear regression and nonlinear neural network

  15. Global Significant Earthquake Database, 2150 BC to present

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Significant Earthquake Database is a global listing of over 5,700 earthquakes from 2150 BC to the present. A significant earthquake is classified as one that...

  16. Global Significant Volcanic Eruptions Database, 4360 BC to present

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Significant Volcanic Eruptions Database is a global listing of over 600 eruptions from 4360 BC to the present. A significant eruption is classified as one that...

  17. Impact of global climate change on ecosystem-level interactions among sympatric plants from all three photosynthetic pathways. Terminal report

    Energy Technology Data Exchange (ETDEWEB)

    Nobel, P.S.

    1997-12-17

    The proposed research will determine biochemical and physiological responses to variations in environmental factors for plants of all three photosynthetic pathways under competitive situations in the field. These responses will be used to predict the effects of global climatic change on an ecosystem in the northwestern Sonoran Desert where the C{sub 3} subshrub Encelia farinosa, the C{sub 4} bunchgrass Hilaria rigida, and the CAM succulent Agave deserti are co-dominants. These perennials are relatively short with overlapping shallow roots facilitating the experimental measurements as well as leading to competition for soil water. Net CO{sub 2} uptake over 24-h periods measured in the laboratory will be analyzed using an environmental productivity index (EPI) that can incorporate simultaneous effects of soil water, air temperature, and light. Based on EPI, net CO{sub 2} uptake and hence plant productivity will be predicted for the three species in the field under various treatments. Activity of the two CO{sub 2} fixation enzymes, Rubisco and PEPCase, will be determined for these various environmental conditions; also, partitioning of carbon to various organs will be measured based on {sup 14}CO{sub 2} labeling and dry weight analysis. Thus, enzymatic and partitioning controls on competition among sympatric model plants representing all three photosynthetic pathways will be investigated.

  18. Photosynthetic response to globally increasing CO2 of co-occurring temperate seagrass species

    DEFF Research Database (Denmark)

    Borum, Jens; Pedersen, Ole; Kotula, Lukasz

    2016-01-01

    Photosynthesis of most seagrass species seems to be limited by present concentrations of dissolved inorganic carbon (DIC). Therefore, the ongoing increase in atmospheric CO2 could enhance seagrass photosynthesis and internal O2 supply, and potentially change species competition through differential...... responses to increasing CO2 availability among species. We used short-term photosynthetic responses of nine seagrass species from the south-west of Australia to test species-specific responses to enhanced CO2 and changes in HCO3 -. Net photosynthesis of all species except Zostera polychlamys were limited...... at pre-industrial compared to saturating CO2 levels at light saturation, suggesting that enhanced CO2 availability will enhance seagrass performance. Seven out of the nine species were efficient HCO3 - users through acidification of diffusive boundary layers, production of extracellular carbonic...

  19. Photosynthetic response to globally increasing CO2 of co-occurring temperate seagrass species.

    Science.gov (United States)

    Borum, Jens; Pedersen, Ole; Kotula, Lukasz; Fraser, Matthew W; Statton, John; Colmer, Timothy D; Kendrick, Gary A

    2016-06-01

    Photosynthesis of most seagrass species seems to be limited by present concentrations of dissolved inorganic carbon (DIC). Therefore, the ongoing increase in atmospheric CO2 could enhance seagrass photosynthesis and internal O2 supply, and potentially change species competition through differential responses to increasing CO2 availability among species. We used short-term photosynthetic responses of nine seagrass species from the south-west of Australia to test species-specific responses to enhanced CO2 and changes in HCO3 (-) . Net photosynthesis of all species except Zostera polychlamys were limited at pre-industrial compared to saturating CO2 levels at light saturation, suggesting that enhanced CO2 availability will enhance seagrass performance. Seven out of the nine species were efficient HCO3 (-) users through acidification of diffusive boundary layers, production of extracellular carbonic anhydrase, or uptake and internal conversion of HCO3 (-) . Species responded differently to near saturating CO2 implying that increasing atmospheric CO2 may change competition among seagrass species if co-occurring in mixed beds. Increasing CO2 availability also enhanced internal aeration in the one species assessed. We expect that future increases in atmospheric CO2 will have the strongest impact on seagrass recruits and sparsely vegetated beds, because densely vegetated seagrass beds are most often limited by light and not by inorganic carbon. © 2015 John Wiley & Sons Ltd.

  20. Drowning unconformities: Palaeoenvironmental significance and involvement of global processes

    Science.gov (United States)

    Godet, Alexis

    2013-07-01

    Drowning unconformities are stratigraphic key surfaces in the history of carbonate platforms. They mostly consist in the deposition of deep marine facies on top of shallow marine limestones. Although large-scale depositional geometries mimic lowstand systems track architecture, these sedimentary turnovers are developed in relation with major sea level rise, inducing an increase in the rate of creation of accommodation space that outpaces the capacity of carbonate to keep up. This so-called paradox of carbonate platform drowning implies that parameters other than purely eustatic fluctuations are involved in the demise of shallow marine ecosystems. Worldwide and at different times during Earth history, in-depth studies of drowning unconformities revealed that changes in nutrient input, clastic delivery, temperature, or a combination of them may be responsible for a decrease in light penetration in the water column and the progressive suffocation and poisoning of photosynthetic carbonate producers. The examination of such case examples from various stratigraphic intervals and palaeogeographical settings thus helps in identifying and hierarchizing potential triggering mechanisms for drowning unconformities. This is complemented by new data from Early Cretaceous successions from the Helvetic Alps. During this time period, the Helvetic carbonate platform developed along the northern Tethyan margin using both photozoan and heterozoan communities. Phases of healthy production were interrupted by several drowning episodes. The latter are marked in the sedimentary record by condensation and associated phosphogenesis and glauconitisation. From the earliest Valanginian to the early to late Barremian, three drowning unconformities reflect the intermittent installation of a more humid climate and subsequent enhanced trophic conditions, which first induced a switch from photozoan to heterozoan communities and then to long-lasting drowning phases. The latter encompass several sea

  1. Identification of significant features by the Global Mean Rank test.

    Science.gov (United States)

    Klammer, Martin; Dybowski, J Nikolaj; Hoffmann, Daniel; Schaab, Christoph

    2014-01-01

    With the introduction of omics-technologies such as transcriptomics and proteomics, numerous methods for the reliable identification of significantly regulated features (genes, proteins, etc.) have been developed. Experimental practice requires these tests to successfully deal with conditions such as small numbers of replicates, missing values, non-normally distributed expression levels, and non-identical distributions of features. With the MeanRank test we aimed at developing a test that performs robustly under these conditions, while favorably scaling with the number of replicates. The test proposed here is a global one-sample location test, which is based on the mean ranks across replicates, and internally estimates and controls the false discovery rate. Furthermore, missing data is accounted for without the need of imputation. In extensive simulations comparing MeanRank to other frequently used methods, we found that it performs well with small and large numbers of replicates, feature dependent variance between replicates, and variable regulation across features on simulation data and a recent two-color microarray spike-in dataset. The tests were then used to identify significant changes in the phosphoproteomes of cancer cells induced by the kinase inhibitors erlotinib and 3-MB-PP1 in two independently published mass spectrometry-based studies. MeanRank outperformed the other global rank-based methods applied in this study. Compared to the popular Significance Analysis of Microarrays and Linear Models for Microarray methods, MeanRank performed similar or better. Furthermore, MeanRank exhibits more consistent behavior regarding the degree of regulation and is robust against the choice of preprocessing methods. MeanRank does not require any imputation of missing values, is easy to understand, and yields results that are easy to interpret. The software implementing the algorithm is freely available for academic and commercial use.

  2. Seagrass meadows as a globally significant carbonate reservoir

    KAUST Repository

    Mazarrasa, I.; Marbà , N.; Lovelock, C. E.; Serrano, O.; Lavery, P. S.; Fourqurean, J. W.; Kennedy, H.; Mateo, M. A.; Krause-Jensen, D.; Steven, A. D. L.; Duarte, Carlos M.

    2015-01-01

    There has been growing interest in quantifying the capacity of seagrass ecosystems to act as carbon sinks as a natural way of offsetting anthropogenic carbon emissions to the atmosphere. However, most of the efforts have focused on the particulate organic carbon (POC) stocks and accumulation rates and ignored the particulate inorganic carbon (PIC) fraction, despite important carbonate pools associated with calcifying organisms inhabiting the meadows, such as epiphytes and benthic invertebrates, and despite the relevance that carbonate precipitation and dissolution processes have in the global carbon cycle. This study offers the first assessment of the global PIC stocks in seagrass sediments using a synthesis of published and unpublished data on sediment carbonate concentration from 403 vegetated and 34 adjacent un-vegetated sites. PIC stocks in the top 1 m of sediment ranged between 3 and 1660 Mg PIC ha−1, with an average of 654 ± 24 Mg PIC ha−1, exceeding those of POC reported in previous studies by about a factor of 5. Sedimentary carbonate stocks varied across seagrass communities, with meadows dominated by Halodule, Thalassia or Cymodocea supporting the highest PIC stocks, and tended to decrease polewards at a rate of −8 ± 2 Mg PIC ha−1 per degree of latitude (general linear model, GLM; p < 0.0003). Using PIC concentrations and estimates of sediment accretion in seagrass meadows, the mean PIC accumulation rate in seagrass sediments is found to be 126.3 ± 31.05 g PIC m−2 yr−1. Based on the global extent of seagrass meadows (177 000 to 600 000 km2), these ecosystems globally store between 11 and 39 Pg of PIC in the top metre of sediment and accumulate between 22 and 75 Tg PIC yr−1, representing a significant contribution to the carbonate dynamics of coastal areas. Despite the fact that these high rates of carbonate accumulation imply CO2

  3. Seagrass meadows as a globally significant carbonate reservoir

    KAUST Repository

    Mazarrasa, I.

    2015-08-24

    There has been growing interest in quantifying the capacity of seagrass ecosystems to act as carbon sinks as a natural way of offsetting anthropogenic carbon emissions to the atmosphere. However, most of the efforts have focused on the particulate organic carbon (POC) stocks and accumulation rates and ignored the particulate inorganic carbon (PIC) fraction, despite important carbonate pools associated with calcifying organisms inhabiting the meadows, such as epiphytes and benthic invertebrates, and despite the relevance that carbonate precipitation and dissolution processes have in the global carbon cycle. This study offers the first assessment of the global PIC stocks in seagrass sediments using a synthesis of published and unpublished data on sediment carbonate concentration from 403 vegetated and 34 adjacent un-vegetated sites. PIC stocks in the top 1 m of sediment ranged between 3 and 1660 Mg PIC ha−1, with an average of 654 ± 24 Mg PIC ha−1, exceeding those of POC reported in previous studies by about a factor of 5. Sedimentary carbonate stocks varied across seagrass communities, with meadows dominated by Halodule, Thalassia or Cymodocea supporting the highest PIC stocks, and tended to decrease polewards at a rate of −8 ± 2 Mg PIC ha−1 per degree of latitude (general linear model, GLM; p < 0.0003). Using PIC concentrations and estimates of sediment accretion in seagrass meadows, the mean PIC accumulation rate in seagrass sediments is found to be 126.3 ± 31.05 g PIC m−2 yr−1. Based on the global extent of seagrass meadows (177 000 to 600 000 km2), these ecosystems globally store between 11 and 39 Pg of PIC in the top metre of sediment and accumulate between 22 and 75 Tg PIC yr−1, representing a significant contribution to the carbonate dynamics of coastal areas. Despite the fact that these high rates of carbonate accumulation imply CO2

  4. Global conservation significance of Ecuador's Yasuní National Park.

    Directory of Open Access Journals (Sweden)

    Margot S Bass

    Full Text Available BACKGROUND: The threats facing Ecuador's Yasuní National Park are emblematic of those confronting the greater western Amazon, one of the world's last high-biodiversity wilderness areas. Notably, the country's second largest untapped oil reserves--called "ITT"--lie beneath an intact, remote section of the park. The conservation significance of Yasuní may weigh heavily in upcoming state-level and international decisions, including whether to develop the oil or invest in alternatives. METHODOLOGY/PRINCIPAL FINDINGS: We conducted the first comprehensive synthesis of biodiversity data for Yasuní. Mapping amphibian, bird, mammal, and plant distributions, we found eastern Ecuador and northern Peru to be the only regions in South America where species richness centers for all four taxonomic groups overlap. This quadruple richness center has only one viable strict protected area (IUCN levels I-IV: Yasuní. The park covers just 14% of the quadruple richness center's area, whereas active or proposed oil concessions cover 79%. Using field inventory data, we compared Yasuní's local (alpha and landscape (gamma diversity to other sites, in the western Amazon and globally. These analyses further suggest that Yasuní is among the most biodiverse places on Earth, with apparent world richness records for amphibians, reptiles, bats, and trees. Yasuní also protects a considerable number of threatened species and regional endemics. CONCLUSIONS/SIGNIFICANCE: Yasuní has outstanding global conservation significance due to its extraordinary biodiversity and potential to sustain this biodiversity in the long term because of its 1 large size and wilderness character, 2 intact large-vertebrate assemblage, 3 IUCN level-II protection status in a region lacking other strict protected areas, and 4 likelihood of maintaining wet, rainforest conditions while anticipated climate change-induced drought intensifies in the eastern Amazon. However, further oil development in

  5. On the global relationships between photosynthetic water-use efficiency, leaf mass per unit area and atmospheric demand in woody and herbaceous plants

    Science.gov (United States)

    Letts, M. G.; Fox, T. A.; Gulias, J.; Galmes, J.; Hikosaka, K.; Wright, I.; Flexas, J.; Awada, T.; Rodriguez-Calcerrada, J.; Tobita, H.

    2013-12-01

    A global dataset was compiled including woody and herbaceous C3 species from forest, Mediterranean and grassland-shrubland ecosystems, to elucidate the dependency of photosynthetic water-use efficiency on vapour pressure deficit (D) and leaf traits. Mean leaf mass per unit area (LMA) was lower and mass-based leaf nitrogen content (Nmass) was higher in herbaceous species. Higher mean stomatal conductance (gs), transpiration rate (E) and net CO2 assimilation rate under light saturating conditions (Amax) were observed in herbs, but photosynthetic and intrinsic water-use efficiencies (WUE = Amax/E and WUEi = Amax/gs) were lower than in woody plants. Woody species maintained stricter stomatal regulation of water loss at low D, resulting in a steeper positive and linear relationship between log D and log E. Herbaceous species possessed very high gs at low D, resulting in higher ratio of substomatal to atmospheric CO2 concentrations (ci/ca) and E, but lower WUE and WUEi than woody plants, despite higher Amax. The lower WUE and higher rates of gas exchange were most pronounced in herbs with low LMA and high Nmass. Photosynthetic water use also differed between species from grassland-shrubland and Mediterranean or forest environments. Water-use efficiency showed no relationship with either D or LMA in grassland-shrubland species, but showed a negative relationship with D in forest and chaparral. The distinct photosynthetic water-use of woody and herbaceous plants is consistent with the opportunistic growth strategy of herbs and the more conservative growth strategy of woody species. Further research is recommended to examine the implications of these functional group and ecosystem differences in the contexts of climate and atmospheric change.

  6. Australia's Uranium and thorium resources and their global significance

    International Nuclear Information System (INIS)

    Lambert, I.B.; McKay, A.; Miezitis, Y.

    2006-01-01

    Full text: Full text: Australia's world-leading uranium endowment appears to result from the emplacement of uranium enriched felsic igneous rocks in three major periods during the geological evolution of the continent. Australia has over 27% of the world's total reasonably assured uranium resources (RAR) recoverable at < US$80/kgU (which approximates recent uranium spot prices). Olympic Dam is the largest known uranium deposit, containing approximately 19% of global RAR (and over 40% of global inferred resources) recoverable at < US$80/kg U; the uranium is present at low concentrations and the viability of its recovery is underpinned by co-production of copper and gold. Most of Australia's other identified resources are within Ranger, Jabiluka, Koongarra, Kintyre and Yeelirrie, the last four of which are not currently accessible for mining. In 2004, Australia's three operating uranium mines - Ranger, Olympic Dam, and Beverley -produced 22% of global production. Canada was the only country to produce more uranium (29%) and Kazakhstan (9%) ranked third. Considerably increased uranium production has been recently foreshadowed from Australia (through developing a large open pit at Olympic Dam), Canada (mainly through opening of the Cigar Lake mine), and Kazakhstan (developing several new in situ leach mines). These increases should go a long way towards satisfying demand from about 2010. Olympic Dam has sufficient resources to sustain such increased production over many decades. Thorium is expected to be used in some future generations of nuclear reactors. Australia also has major (but incompletely quantified) resources of this commodity, mainly in heavy mineral sands deposits and associated with alkaline igneous rocks. It is inevitable that the international community will be looking increasingly to Australia to sustain its vital role in providing fuels for future nuclear power generation, given its world-leading identified resources, considerable potential for new

  7. Globally significant greenhouse-gas emissions from African inland waters

    Science.gov (United States)

    Borges, Alberto V.; Bouillon, Steven

    2017-04-01

    The relevance of inland waters to global biogeochemical cycles is increasingly recognized, and of particular importance is their contribution of greenhouse gases to the atmosphere. The latter remain largely unreported in African inland waters. Here we report dissolved CO2, CH4 and N2O from 12 rivers in Sub-Saharan Africa acquired during >30 field expeditions and additional seasonally resolved sampling at >30 sites between 2006 and 2014. Fluxes were calculated from reported gas transfer velocity values, and upscaled using available spatial datasets, with an estimated uncertainty of about ±19%. CO2 equivalent emissions ( 0.4±0.1 PgC yr-1) match 2/3 of the overall net carbon sink previously reported for Africa. Including emissions from wetlands of the Congo, the putative total emission ( 0.9±0.1 PgC yr-1) is about half of the global oceanic or land carbon sinks. In-situ respiration supported <14% of riverine CO2 emissions, which must therefore largely be driven by mineralization in wetlands or uplands. Riverine CO2 and CH4 emissions were directly correlated to wetland coverage and aboveground vegetation biomass, implying that future changes in wetland and upland vegetation cover will strongly impact GHG emissions from African inland waters.

  8. Permafrost Stores a Globally Significant Amount of Mercury

    Science.gov (United States)

    Schuster, Paul F.; Schaefer, Kevin M.; Aiken, George R.; Antweiler, Ronald C.; Dewild, John F.; Gryziec, Joshua D.; Gusmeroli, Alessio; Hugelius, Gustaf; Jafarov, Elchin; Krabbenhoft, David P.; Liu, Lin; Herman-Mercer, Nicole; Mu, Cuicui; Roth, David A.; Schaefer, Tim; Striegl, Robert G.; Wickland, Kimberly P.; Zhang, Tingjun

    2018-02-01

    Changing climate in northern regions is causing permafrost to thaw with major implications for the global mercury (Hg) cycle. We estimated Hg in permafrost regions based on in situ measurements of sediment total mercury (STHg), soil organic carbon (SOC), and the Hg to carbon ratio (RHgC) combined with maps of soil carbon. We measured a median STHg of 43 ± 30 ng Hg g soil-1 and a median RHgC of 1.6 ± 0.9 μg Hg g C-1, consistent with published results of STHg for tundra soils and 11,000 measurements from 4,926 temperate, nonpermafrost sites in North America and Eurasia. We estimate that the Northern Hemisphere permafrost regions contain 1,656 ± 962 Gg Hg, of which 793 ± 461 Gg Hg is frozen in permafrost. Permafrost soils store nearly twice as much Hg as all other soils, the ocean, and the atmosphere combined, and this Hg is vulnerable to release as permafrost thaws over the next century. Existing estimates greatly underestimate Hg in permafrost soils, indicating a need to reevaluate the role of the Arctic regions in the global Hg cycle.

  9. Permafrost stores a globally significant amount of mercury

    Science.gov (United States)

    Schuster, Paul F.; Schaefer, Kevin; Aiken, George R.; Antweiler, Ronald C.; DeWild, John F.; Gryziec, Joshua D.; Gusmeroli, Alessio; Hugelius, Gustaf; Jafarov, Elchin E.; Krabbenhoft, David P.; Liu, Lin; Herman-Mercer, Nicole M.; Mu, Cuicui; Roth, David A.; Schaefer, Tim; Striegl, Robert G.; Wickland, Kimberly P.; Zhang, Tingjun

    2018-01-01

    Changing climate in northern regions is causing permafrost to thaw with major implications for the global mercury (Hg) cycle. We estimated Hg in permafrost regions based on in situ measurements of sediment total mercury (STHg), soil organic carbon (SOC), and the Hg to carbon ratio (RHgC) combined with maps of soil carbon. We measured a median STHg of 43 ± 30 ng Hg g soil−1 and a median RHgC of 1.6 ± 0.9 μg Hg g C−1, consistent with published results of STHg for tundra soils and 11,000 measurements from 4,926 temperate, nonpermafrost sites in North America and Eurasia. We estimate that the Northern Hemisphere permafrost regions contain 1,656 ± 962 Gg Hg, of which 793 ± 461 Gg Hg is frozen in permafrost. Permafrost soils store nearly twice as much Hg as all other soils, the ocean, and the atmosphere combined, and this Hg is vulnerable to release as permafrost thaws over the next century. Existing estimates greatly underestimate Hg in permafrost soils, indicating a need to reevaluate the role of the Arctic regions in the global Hg cycle.

  10. A Conceptual Model for Projecting Coccolithophorid Growth, Calcification and Photosynthetic Carbon Fixation Rates in Response to Global Ocean Change

    Directory of Open Access Journals (Sweden)

    Natasha A. Gafar

    2018-01-01

    Full Text Available Temperature, light and carbonate chemistry all influence the growth, calcification and photosynthetic rates of coccolithophores to a similar degree. There have been multiple attempts to project the responses of coccolithophores to changes in carbonate chemistry, but the interaction with light and temperature remains elusive. Here we devise a simple conceptual model to derive a fit equation for coccolithophorid growth, photosynthetic and calcification rates in response to simultaneous changes in carbonate chemistry, temperature and light conditions. The fit equation is able to account for up to 88% of the variability in measured metabolic rates. Equation projections indicate that temperature, light and carbonate chemistry all have different modulating effects on both optimal growth conditions and the sensitivity of responses to extreme environmental conditions. Calculations suggest that a single extreme environmental condition (CO2, temperature, light will reduce maximum rates regardless of how optimal the other environmental conditions may be. Thus, while the response of coccolithophores to ocean change depends on multiple variables, the one which is least optimal will have the most impact on overall rates. Finally, responses to ocean change are usually reported in terms of cellular rates. However, changes in cellular rates can be a poor predictor for assessing changes in production at the community level. We therefore introduce a new metric, the calcium carbonate production potential (CCPP, which combines the independent effects of changes in growth rate and cellular calcium carbonate content to assess how environmental changes will impact coccolith production. Direct comparison of CO2 impacts on cellular CaCO3 production rates and CCPP shows that while the former is still at 45% of its pre-industrial capacity at 1,000 μatm, the latter is reduced to 10%.

  11. The role of energy losses in photosynthetic light harvesting

    NARCIS (Netherlands)

    Kruger, T. P. J.; van Grondelle, R.

    2017-01-01

    Photosynthesis operates at the bottom of the food chain to convert the energy of light into carbohydrates at a remarkable global rate of about 130 TW. Nonetheless, the overall photosynthetic process has a conversion efficiency of a few percent at best, significantly less than bottom-up photovoltaic

  12. Habitats at Risk. Global Warming and Species Loss in Globally Significant Terrestrial Ecosystems

    International Nuclear Information System (INIS)

    Malcolm, J.R.; Liu, Canran; Miller, L.B.; Allnutt, T.; Hansen, L.

    2002-02-01

    In this study, a suite of models of global climate and vegetation change is used to investigate three important global warming-induced threats to the terrestrial Global 200 ecoregions: (1) Invasions by new habitat types (and corresponding loss of original habitat types); (2) Local changes of habitat types; (3) High rates of required species migration. Seven climate models (general circulation models or GCMs) and two vegetation models (BIOME3 and MAPSS) were used to produce 14 impact scenarios under the climate associated with a doubling of atmospheric CO2 concentrations, which is expected to occur in less than 100 years. Previous analyses indicated that most of the variation among the impact scenarios was attributable to the particular vegetation model used, hence the authors provide results separately for the two models. The models do not provide information on biodiversity per se, but instead simulate current and future potential distributions of major vegetation types (biomes) such as tundra and broadleaf tropical rain forest

  13. [Engineering photosynthetic cyanobacterial chassis: a review].

    Science.gov (United States)

    Wu, Qin; Chen, Lei; Wang, Jiangxin; Zhang, Weiwen

    2013-08-01

    Photosynthetic cyanobacteria possess a series of good properties, such as their abilities to capture solar energy for CO2 fixation, low nutritional requirements for growth, high growth rate, and relatively simple genetic background. Due to the high oil price and increased concern of the global warming in recent years, cyanobacteria have attracted widespread attention because they can serve as an 'autotrophic microbial factory' for producing renewable biofuels and fine chemicals directly from CO2. Particularly, significant progress has been made in applying synthetic biology techniques and strategies to construct and optimize cyanobacteria chassis. In this article, we critically summarized recent advances in developing new methods to optimize cyanobacteria chassis, improving cyanobacteria photosynthetic efficiency, and in constructing cyanobacteria chassis tolerant to products or environmental stresses. In addition, various industrial applications of cyanobacteria chassis are also discussed.

  14. A long-term time series of global and diffuse photosynthetically active radiation in the Mediterranean: interannual variability and cloud effects

    Directory of Open Access Journals (Sweden)

    P. Trisolino

    2018-06-01

    Full Text Available Measurements of global and diffuse photosynthetically active radiation (PAR have been carried out on the island of Lampedusa, in the central Mediterranean Sea, since 2002. PAR is derived from observations made with multi-filter rotating shadowband radiometers (MFRSRs by comparison with a freshly calibrated PAR sensor and by relying on the on-site Langley plots. In this way, a long-term calibrated record covering the period 2002–2016 is obtained and is presented in this work. The monthly mean global PAR peaks in June, with about 160 W m−2, while the diffuse PAR reaches 60 W m−2 in spring or summer. The global PAR displays a clear annual cycle with a semi amplitude of about 52 W m−2. The diffuse PAR annual cycle has a semi amplitude of about 12 W m−2. A simple method to retrieve the cloud-free PAR global and diffuse irradiances in days characterized by partly cloudy conditions has been implemented and applied to the dataset. This method allows retrieval of the cloud-free evolution of PAR and calculation of the cloud radiative effect, CRE, for downwelling PAR. The cloud-free monthly mean global PAR reaches 175 W m−2 in summer, while the diffuse PAR peaks at about 40 W m−2. The cloud radiative effect, CRE, on global and diffuse PAR is calculated as the difference between all-sky and cloud-free measurements. The annual average CRE is about −14.7 W m−2 for the global PAR and +8.1 W m−2 for the diffuse PAR. The smallest CRE is observed in July, due to the high cloud-free condition frequency. Maxima (negative for the global, and positive for the diffuse component occur in March–April and in October, due to the combination of elevated PAR irradiances and high occurrence of cloudy conditions. Summer clouds appear to be characterized by a low frequency of occurrence, low altitude, and low optical thickness, possibly linked to the peculiar marine boundary layer structure. These properties also contribute

  15. Estimation of Radiative Efficiency of Chemicals with Potentially Significant Global Warming Potential

    Data.gov (United States)

    U.S. Environmental Protection Agency — The set of commercially available chemical substances in commerce that may have significant global warming potential (GWP) is not well defined. Although there are...

  16. Should we expect financial globalization to have significant effects on business cycles?

    OpenAIRE

    Iversen, Jens

    2009-01-01

    Empirical research suggests that financial globalization has insignificant effects on business cycles. Based on standard theoretical models it might be conjectured that the effects should be significant. I show that this conjecture is wrong. Theoretical effects of financial globalization can be determined to any level of precision by expanding the underlying artificial samples. In contrast, in the data the effects are imprecisely estimated because of short samples. I show that if the conclusi...

  17. Plant communities as drivers of soil respiration: pathways, mechanisms, and significance for global change

    Science.gov (United States)

    Metcalfe, D. B.; Fisher, R. A.; Wardle, D. A.

    2011-08-01

    Understanding the impacts of plant community characteristics on soil carbon dioxide efflux (R) is a key prerequisite for accurate prediction of the future carbon (C) balance of terrestrial ecosystems under climate change. However, developing a mechanistic understanding of the determinants of R is complicated by the presence of multiple different sources of respiratory C within soil - such as soil microbes, plant roots and their mycorrhizal symbionts - each with their distinct dynamics and drivers. In this review, we synthesize relevant information from a wide spectrum of sources to evaluate the current state of knowledge about plant community effects on R, examine how this information is incorporated into global climate models, and highlight priorities for future research. Despite often large variation amongst studies and methods, several general trends emerge. Mechanisms whereby plants affect R may be grouped into effects on belowground C allocation, aboveground litter properties and microclimate. Within vegetation types, the amount of C diverted belowground, and hence R, may be controlled mainly by the rate of photosynthetic C uptake, while amongst vegetation types this should be more dependent upon the specific C allocation strategies of the plant life form. We make the case that plant community composition, rather than diversity, is usually the dominant control on R in natural systems. Individual species impacts on R may be largest where the species accounts for most of the biomass in the ecosystem, has very distinct traits to the rest of the community and/or modulates the occurrence of major natural disturbances. We show that climate vegetation models incorporate a number of pathways whereby plants can affect R, but that simplifications regarding allocation schemes and drivers of litter decomposition may limit model accuracy. We also suggest that under a warmer future climate, many plant communities may shift towards dominance by fast growing plants which

  18. Surface water change as a significant contributor to global evapotranspiration change

    Science.gov (United States)

    Zhan, S.; Song, C.

    2017-12-01

    Water comprises a critical component of global/regional hydrological and biogeochemical cycles and is essential to all organisms including humans. In the past several decades, climate change has intensified the hydrological cycle, with significant implications for ecosystem services and feedback to regional and global climate. Evapotranspiration (ET) as a linking mechanism between land surface and atmosphere is central to the water cycle and an excellent indicator of the intensity of water cycle. Knowledge of the temporal changes of ET is crucial for accurately estimating global or regional water budgets and better understanding climate and hydrological interactions. While studies have examined changes in global ET, they were conducted using a constant land and surface water (SW) area. However, as many studies have found that global SW is very dynamic and their surface areas have generally been increasing since the 1980s. The conversion from land to water and vice versa significantly changes the local ET since water bodies evaporate at a rate that can be much higher than that of the land. Here, we quantify the global changes in ET caused by such land-water conversion using remotely-sensed SW area and various ET and potential ET products. New SW and lost SW between circa-1985 and circa-2015 were derived from remote sensing and were used to modify the local ET estimates. We found an increase in ET in all continents as consistent with the net increase in SW area. The increasing SW area lead to a global increase in ET by 30.38 ± 5.28 km3/yr. This is a significant contribution when compared to the 92.95 km3/yr/yr increase in ET between 1982-1997 and 103.43 km3/yr/yr decrease between 1998-2008 by Jung et al., (2010) assuming a constant SW. The results enhance our understanding of the water fluxes between the land and atmosphere and supplement land water budget estimates. We conclude that changes in SW lead to a significant change in global ET that cannot be neglected in

  19. Future role and significance of space activities in reflection of global social, technological and economic trends

    Science.gov (United States)

    Diekmann, Andreas; Richarz, Hans.-Peter

    The paper describes the interrelation of space activities and global socio-economic trends like "globalisation of markets" and "renaissance of fine arts". The interrelation reveals the economic strategic, technological and scientific dimension of space activities and their benefits to mankind. Then, the significance and perspectives of space activities in these dimensions are examined in more detail. The paper calls (1) for a more visible initiative to employ space activities to tackle urgent questions of global change and development, and (2) for a stronger impetus to secure European economic position in space sector as a key industry of the 21st century.

  20. Plant communities as drivers of soil respiration: pathways, mechanisms, and significance for global change

    Directory of Open Access Journals (Sweden)

    D. B. Metcalfe

    2011-08-01

    Full Text Available Understanding the impacts of plant community characteristics on soil carbon dioxide efflux (R is a key prerequisite for accurate prediction of the future carbon (C balance of terrestrial ecosystems under climate change. However, developing a mechanistic understanding of the determinants of R is complicated by the presence of multiple different sources of respiratory C within soil – such as soil microbes, plant roots and their mycorrhizal symbionts – each with their distinct dynamics and drivers. In this review, we synthesize relevant information from a wide spectrum of sources to evaluate the current state of knowledge about plant community effects on R, examine how this information is incorporated into global climate models, and highlight priorities for future research. Despite often large variation amongst studies and methods, several general trends emerge.

    Mechanisms whereby plants affect R may be grouped into effects on belowground C allocation, aboveground litter properties and microclimate. Within vegetation types, the amount of C diverted belowground, and hence R, may be controlled mainly by the rate of photosynthetic C uptake, while amongst vegetation types this should be more dependent upon the specific C allocation strategies of the plant life form. We make the case that plant community composition, rather than diversity, is usually the dominant control on R in natural systems. Individual species impacts on R may be largest where the species accounts for most of the biomass in the ecosystem, has very distinct traits to the rest of the community and/or modulates the occurrence of major natural disturbances. We show that climate vegetation models incorporate a number of pathways whereby plants can affect R, but that simplifications regarding allocation schemes and drivers of litter decomposition may limit model accuracy. We also suggest that under a warmer future

  1. Photosynthetic Pigments in Diatoms.

    Science.gov (United States)

    Kuczynska, Paulina; Jemiola-Rzeminska, Malgorzata; Strzalka, Kazimierz

    2015-09-16

    Photosynthetic pigments are bioactive compounds of great importance for the food, cosmetic, and pharmaceutical industries. They are not only responsible for capturing solar energy to carry out photosynthesis, but also play a role in photoprotective processes and display antioxidant activity, all of which contribute to effective biomass and oxygen production. Diatoms are organisms of a distinct pigment composition, substantially different from that present in plants. Apart from light-harvesting pigments such as chlorophyll a, chlorophyll c, and fucoxanthin, there is a group of photoprotective carotenoids which includes β-carotene and the xanthophylls, diatoxanthin, diadinoxanthin, violaxanthin, antheraxanthin, and zeaxanthin, which are engaged in the xanthophyll cycle. Additionally, some intermediate products of biosynthetic pathways have been identified in diatoms as well as unusual pigments, e.g., marennine. Marine algae have become widely recognized as a source of unique bioactive compounds for potential industrial, pharmaceutical, and medical applications. In this review, we summarize current knowledge on diatom photosynthetic pigments complemented by some new insights regarding their physico-chemical properties, biological role, and biosynthetic pathways, as well as the regulation of pigment level in the cell, methods of purification, and significance in industries.

  2. Photosynthetic Pigments in Diatoms

    Directory of Open Access Journals (Sweden)

    Paulina Kuczynska

    2015-09-01

    Full Text Available Photosynthetic pigments are bioactive compounds of great importance for the food, cosmetic, and pharmaceutical industries. They are not only responsible for capturing solar energy to carry out photosynthesis, but also play a role in photoprotective processes and display antioxidant activity, all of which contribute to effective biomass and oxygen production. Diatoms are organisms of a distinct pigment composition, substantially different from that present in plants. Apart from light-harvesting pigments such as chlorophyll a, chlorophyll c, and fucoxanthin, there is a group of photoprotective carotenoids which includes β-carotene and the xanthophylls, diatoxanthin, diadinoxanthin, violaxanthin, antheraxanthin, and zeaxanthin, which are engaged in the xanthophyll cycle. Additionally, some intermediate products of biosynthetic pathways have been identified in diatoms as well as unusual pigments, e.g., marennine. Marine algae have become widely recognized as a source of unique bioactive compounds for potential industrial, pharmaceutical, and medical applications. In this review, we summarize current knowledge on diatom photosynthetic pigments complemented by some new insights regarding their physico-chemical properties, biological role, and biosynthetic pathways, as well as the regulation of pigment level in the cell, methods of purification, and significance in industries.

  3. The prognostic significance of whole blood global and specific DNA methylation levels in gastric adenocarcinoma.

    Directory of Open Access Journals (Sweden)

    Mansour S Al-Moundhri

    Full Text Available BACKGROUND: Epigenetics, particularly DNA methylation, has recently been elucidated as important in gastric cancer (GC initiation and progression. We investigated the clinical and prognostic importance of whole blood global and site-specific DNA methylation in GC. METHODS: Genomic DNA was extracted from the peripheral blood of 105 Omani GC patients at diagnosis. DNA methylation was quantified by pyrosequencing of global DNA and specific gene promoter regions at 5 CpG sites for CDH1, 7 CpG sites for p16, 4 CpG sites for p53, and 3 CpG sites for RUNX3. DNA methylation levels in patients were categorized into low, medium, and high tertiles. Associations between methylation level category and clinicopathological features were evaluated using χ(2 tests. Survival analyses were carried out using the Kaplan-Meier method and log rank test. A backward conditional Cox proportional hazards regression model was used to identify independent predictors of survival. RESULTS: Older GC patients had increased methylation levels at specific CpG sites within the CDH1, p53, and RUNX-3 promoters. Male gender was significantly associated with reduced global and increased site-specific DNA methylation levels in CDH1, p16, and p53 promoters. Global DNA low methylation level was associated with better survival on univariate analysis. Patients with high and medium methylation vs. low methylation levels across p16 promoter CpG sites, site 2 in particular, had better survival. Multivariate analysis showed that global DNA hypermethylation was a significant independent predictor of worse survival (hazard ratio (HR = 2.0, 95% CI: 1.1-3.8; p = 0.02 and high methylation mean values across p16 promoter sites 1-7 were associated with better survival with HR of 0.3 (95% CI, 0.1-0.8; p = 0.02 respectively. CONCLUSIONS: Analysis of global and site-specific DNA methylation in peripheral blood by pyrosequencing provides quantitative DNA methylation values that may serve as important

  4. Photosynthetic water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Greenbaum, E.

    1981-01-01

    The photosynthetic unit of hydrogen evolution, the turnover time of photosynthetic hydrogen production, and hydrogenic photosynthesis are discussed in the section on previous work. Recent results are given on simultaneous photoproduction of hydrogen and oxygen, kinetic studies, microscopic marine algae-seaweeds, and oxygen profiles.

  5. Significant uncertainty in global scale hydrological modeling from precipitation data errors

    Science.gov (United States)

    Sperna Weiland, Frederiek C.; Vrugt, Jasper A.; van Beek, Rens (L.) P. H.; Weerts, Albrecht H.; Bierkens, Marc F. P.

    2015-10-01

    In the past decades significant progress has been made in the fitting of hydrologic models to data. Most of this work has focused on simple, CPU-efficient, lumped hydrologic models using discharge, water table depth, soil moisture, or tracer data from relatively small river basins. In this paper, we focus on large-scale hydrologic modeling and analyze the effect of parameter and rainfall data uncertainty on simulated discharge dynamics with the global hydrologic model PCR-GLOBWB. We use three rainfall data products; the CFSR reanalysis, the ERA-Interim reanalysis, and a combined ERA-40 reanalysis and CRU dataset. Parameter uncertainty is derived from Latin Hypercube Sampling (LHS) using monthly discharge data from five of the largest river systems in the world. Our results demonstrate that the default parameterization of PCR-GLOBWB, derived from global datasets, can be improved by calibrating the model against monthly discharge observations. Yet, it is difficult to find a single parameterization of PCR-GLOBWB that works well for all of the five river basins considered herein and shows consistent performance during both the calibration and evaluation period. Still there may be possibilities for regionalization based on catchment similarities. Our simulations illustrate that parameter uncertainty constitutes only a minor part of predictive uncertainty. Thus, the apparent dichotomy between simulations of global-scale hydrologic behavior and actual data cannot be resolved by simply increasing the model complexity of PCR-GLOBWB and resolving sub-grid processes. Instead, it would be more productive to improve the characterization of global rainfall amounts at spatial resolutions of 0.5° and smaller.

  6. Prey preferences of the snow leopard (Panthera uncia: regional diet specificity holds global significance for conservation.

    Directory of Open Access Journals (Sweden)

    Salvador Lyngdoh

    Full Text Available The endangered snow leopard is a large felid that is distributed over 1.83 million km(2 globally. Throughout its range it relies on a limited number of prey species in some of the most inhospitable landscapes on the planet where high rates of human persecution exist for both predator and prey. We reviewed 14 published and 11 unpublished studies pertaining to snow leopard diet throughout its range. We calculated prey consumption in terms of frequency of occurrence and biomass consumed based on 1696 analysed scats from throughout the snow leopard's range. Prey biomass consumed was calculated based on the Ackerman's linear correction factor. We identified four distinct physiographic and snow leopard prey type zones, using cluster analysis that had unique prey assemblages and had key prey characteristics which supported snow leopard occurrence there. Levin's index showed the snow leopard had a specialized dietary niche breadth. The main prey of the snow leopard were Siberian ibex (Capra sibrica, blue sheep (Pseudois nayaur, Himalayan tahr (Hemitragus jemlahicus, argali (Ovis ammon and marmots (Marmota spp. The significantly preferred prey species of snow leopard weighed 55±5 kg, while the preferred prey weight range of snow leopard was 36-76 kg with a significant preference for Siberian ibex and blue sheep. Our meta-analysis identified critical dietary resources for snow leopards throughout their distribution and illustrates the importance of understanding regional variation in species ecology; particularly prey species that have global implications for conservation.

  7. Prey preferences of the snow leopard (Panthera uncia): regional diet specificity holds global significance for conservation.

    Science.gov (United States)

    Lyngdoh, Salvador; Shrotriya, Shivam; Goyal, Surendra P; Clements, Hayley; Hayward, Matthew W; Habib, Bilal

    2014-01-01

    The endangered snow leopard is a large felid that is distributed over 1.83 million km(2) globally. Throughout its range it relies on a limited number of prey species in some of the most inhospitable landscapes on the planet where high rates of human persecution exist for both predator and prey. We reviewed 14 published and 11 unpublished studies pertaining to snow leopard diet throughout its range. We calculated prey consumption in terms of frequency of occurrence and biomass consumed based on 1696 analysed scats from throughout the snow leopard's range. Prey biomass consumed was calculated based on the Ackerman's linear correction factor. We identified four distinct physiographic and snow leopard prey type zones, using cluster analysis that had unique prey assemblages and had key prey characteristics which supported snow leopard occurrence there. Levin's index showed the snow leopard had a specialized dietary niche breadth. The main prey of the snow leopard were Siberian ibex (Capra sibrica), blue sheep (Pseudois nayaur), Himalayan tahr (Hemitragus jemlahicus), argali (Ovis ammon) and marmots (Marmota spp). The significantly preferred prey species of snow leopard weighed 55±5 kg, while the preferred prey weight range of snow leopard was 36-76 kg with a significant preference for Siberian ibex and blue sheep. Our meta-analysis identified critical dietary resources for snow leopards throughout their distribution and illustrates the importance of understanding regional variation in species ecology; particularly prey species that have global implications for conservation.

  8. The Significance of Peaceful Values in Global Perspective: Challenges and Hopes

    Directory of Open Access Journals (Sweden)

    Azhar Arsyad

    2016-11-01

    Full Text Available The paper talks about how violence and conflict in every form of life will get anybody nowhere and how the call for peace and tranquility should be implemented by each mankind, wherever he lives and wherever they as a group may reside. Hence, peaceful values in global perspective are of great significance. The questions which may be raised are what do we need to have and what do we need to know prior to talking about peace and tranquility? The other questions which may spur are how to implement peace and what makes peace fail and tranquility never becomes a reality. The answer to those questions will become an elaboration of the gist of this article. Historically and spiritually speaking, peace will not be realized if the reason of failure to achieve peace has not been made aware and known to mankind. Albeit various advices and directions have been given, peace shall not be realized. This is due to the fact that the advice and directions given have not met the substance of the cause and have not been able to provide a comprehensive solution to peace itself. Some of the substances of this article, therefore, will try to prove how the need to recognizing and understanding the “voice of the heart” as “inner-soul” and “inner capacity” themselves will become an essential thing to be realized by every individual, so that they can thereafter be known by all mankind globally wherever they may be.

  9. Global trends in significant wave height and marine wind speed from the ERA-20CM

    Science.gov (United States)

    Aarnes, Ole Johan; Breivik, Øyvind

    2016-04-01

    The ERA-20CM is one of the latest additions to the ERA-series produced at the European Center for Medium-Range Weather Forecasts (ECMWF). This 10 member ensemble is generated with a version of the Integrated Forecast System (IFS), a coupled atmosphere-wave model. The model integration is run as a AMIP (Atmospheric Model Intercomparison Project) constrained by CMIP5 recommended radiative forcing and different realizations of sea-surface temperature (SST) and sea-ice cover (SIC) prescribed by the HadISST2 (Met Office Hadley Center). While the ERA-20CM is unable to reproduce the actual synoptic conditions, it is designed to offer a realistic statistical representation of the past climate, spanning the period 1899-2010. In this study we investigate global trends in significant wave height and marine wind speed based on ERA-20CM, using monthly mean data, upper percentiles and monthly/annual maxima. The aim of the study is to assess the quality of the trends and how these estimates are affected by different SST and SIC. Global trends are compared against corresponding estimates obtained with ERA-Interim (1979-2009), but also crosschecked against ERA-20C - an ECMWF pilot reanalysis of the 20th-century, known to most trustworthy in the Northern Hemisphere extratropics. Over the period 1900-2009, the 10 member ensemble yields trends mainly within +/- 5% per century. However, significant trends of opposite signs are found locally. Certain areas, like the eastern equatorial Pacific, highly affected by the El Niño Southern Oscillation, show stronger trends. In general, trends based on statistical quantities further into the tail of the distribution are found less reliable.

  10. Phytochromes in photosynthetically competent plants

    Energy Technology Data Exchange (ETDEWEB)

    Pratt, L.H.

    1990-07-01

    Plants utilize light as a source of information in photomorphogenesis and of free energy in photosynthesis, two processes that are interrelated in that the former serves to increase the efficiency with which plants can perform the latter. Only one pigment involved in photomorphogenesis has been identified unequivocally, namely phytochrome. The thrust of this proposal is to investigate this pigment and its mode(s) of action in photosynthetically competent plants. Our long term objective is to characterize phytochrome and its functions in photosynthetically competent plants from molecular, biochemical and cellular perspectives. It is anticipated that others will continue to contribute indirectly to these efforts at the physiological level. The ultimate goal will be to develop this information from a comparative perspective in order to learn whether the different phytochromes have significantly different physicochemical properties, whether they fulfill independent functions and if so what these different functions are, and how each of the different phytochromes acts at primary molecular and cellular levels.

  11. Estimation of Radiative Efficiency of Chemicals with Potentially Significant Global Warming Potential.

    Science.gov (United States)

    Betowski, Don; Bevington, Charles; Allison, Thomas C

    2016-01-19

    Halogenated chemical substances are used in a broad array of applications, and new chemical substances are continually being developed and introduced into commerce. While recent research has considerably increased our understanding of the global warming potentials (GWPs) of multiple individual chemical substances, this research inevitably lags behind the development of new chemical substances. There are currently over 200 substances known to have high GWP. Evaluation of schemes to estimate radiative efficiency (RE) based on computational chemistry are useful where no measured IR spectrum is available. This study assesses the reliability of values of RE calculated using computational chemistry techniques for 235 chemical substances against the best available values. Computed vibrational frequency data is used to estimate RE values using several Pinnock-type models, and reasonable agreement with reported values is found. Significant improvement is obtained through scaling of both vibrational frequencies and intensities. The effect of varying the computational method and basis set used to calculate the frequency data is discussed. It is found that the vibrational intensities have a strong dependence on basis set and are largely responsible for differences in computed RE values.

  12. The ecology of methane in streams and rivers: Patterns, controls, and global significance

    Science.gov (United States)

    Stanley, Emily H.; Casson, Nora J.; Christel, Samuel T.; Crawford, John T.; Loken, Luke C.; Oliver, Samantha K.

    2016-01-01

    Streams and rivers can substantially modify organic carbon (OC) inputs from terrestrial landscapes, and much of this processing is the result of microbial respiration. While carbon dioxide (CO2) is the major end-product of ecosystem respiration, methane (CH4) is also present in many fluvial environments even though methanogenesis typically requires anoxic conditions that may be scarce in these systems. Given recent recognition of the pervasiveness of this greenhouse gas in streams and rivers, we synthesized existing research and data to identify patterns and drivers of CH4, knowledge gaps, and research opportunities. This included examining the history of lotic CH4 research, creating a database of concentrations and fluxes (MethDB) to generate a global-scale estimate of fluvial CH4 efflux, and developing a conceptual framework and using this framework to consider how human activities may modify fluvial CH4 dynamics. Current understanding of CH4 in streams and rivers has been strongly influenced by goals of understanding OC processing and quantifying the contribution of CH4 to ecosystem C fluxes. Less effort has been directed towards investigating processes that dictate in situ CH4 production and loss. CH4 makes a meager contribution to watershed or landscape C budgets, but streams and rivers are often significant CH4 sources to the atmosphere across these same spatial extents. Most fluvial systems are supersaturated with CH4 and we estimate an annual global emission of 26.8 Tg CH4, equivalent to ~15-40% of wetland and lake effluxes, respectively. Less clear is the role of CH4 oxidation, methanogenesis, and total anaerobic respiration to whole ecosystem production and respiration. Controls on CH4 generation and persistence can be viewed in terms of proximate controls that influence methanogenesis (organic matter, temperature, alternative electron acceptors, nutrients) and distal geomorphic and hydrologic drivers. Multiple controls combined with its

  13. Are Emissions of Restricted Halocarbons in the USA and Canada Still Globally Significant?

    Science.gov (United States)

    Hurst, D. F.; Romashkin, P. A.; Hall, B. D.; Elkins, J. W.; Lin, J. C.; Gerbig, C.; Daube, B. C.; Wofsy, S. C.

    2004-12-01

    The global manufacture of halocarbons regulated by the Montreal Protocol has dropped substantially in response to the January 1, 1996, production phase-out deadline (1994 for halons) for developed (Article 5) countries like the United States and Canada. Contemporary emissions of these ozone-depleting substances (ODS) emanate from ongoing production in developing countries and releases of banked halocarbons world-wide. ODS emissions in developing nations can be appraised from reported production figures, but not so for developed nations where recent manufacture is negligible. Emissions in the United States and Canada are increasingly difficult to estimate because of limited information about bank sizes and release rates in the post-production era. In addition, regional- or national-scale emission estimates should no longer be derived wholly from localized measurements because of the potentially patchy spatial distributions of modern emissions. We estimate ODS emissions in the USA and Canada from >1000 simultaneous, in situ measurements each of CO and six restricted halocarbons (CFC-11, CFC-12, CFC-113, methyl chloroform, carbon tetrachloride, and halon-1211) in and above the planetary boundary layer during the 2003 CO2 Budget and Regional Airborne - North America (COBRA-NA 2003) study. The data obtained during 87 flight hours are geographically extensive (>30,000 km) including two 11,000 km flight circuits across both countries. More than 50 pollution "events" with statistically significant ODS:CO emission ratios were sampled, and for each event we have determined a flux footprint using the Stochastic Time-Inverted Lagrangian Transport (STILT) model. The model also calculates footprint-weighted average population densities and CO fluxes which we convert to footprint-weighted average ODS fluxes using the measured ODS:CO emission ratios. Statistically robust relationships between footprint-averaged ODS fluxes and population densities for several ODS indicate that

  14. The role of energy losses in photosynthetic light harvesting

    Science.gov (United States)

    Krüger, T. P. J.; van Grondelle, R.

    2017-07-01

    Photosynthesis operates at the bottom of the food chain to convert the energy of light into carbohydrates at a remarkable global rate of about 130 TW. Nonetheless, the overall photosynthetic process has a conversion efficiency of a few percent at best, significantly less than bottom-up photovoltaic cells. The primary photosynthetic steps, consisting of light harvesting and charge separation, are often presented as having near-unity quantum efficiency but this holds only true under ideal conditions. In this review, we discuss the importance of energy loss mechanisms to establish robustness in photosynthetic light harvesting. Thermal energy dissipation of light-harvesting complexes (LHCs) in different environments is investigated and the relationships and contrasts between concentration quenching of high pigment concentrations, photoprotection (non-photochemical quenching), quenching due to protein aggregation, and fluorescence blinking are discussed. The role of charge-transfer states in light harvesting and energy dissipation is highlighted and the importance of controlled protein structural disorder to switch the light-harvesting antennae between effective light harvesters and efficient energy quenchers is underscored. The main LHC of plants, LHCII, is used as a prime example.

  15. The role of energy losses in photosynthetic light harvesting

    International Nuclear Information System (INIS)

    Krüger, T P J; Van Grondelle, R

    2017-01-01

    Photosynthesis operates at the bottom of the food chain to convert the energy of light into carbohydrates at a remarkable global rate of about 130 TW. Nonetheless, the overall photosynthetic process has a conversion efficiency of a few percent at best, significantly less than bottom-up photovoltaic cells. The primary photosynthetic steps, consisting of light harvesting and charge separation, are often presented as having near-unity quantum efficiency but this holds only true under ideal conditions. In this review, we discuss the importance of energy loss mechanisms to establish robustness in photosynthetic light harvesting. Thermal energy dissipation of light-harvesting complexes (LHCs) in different environments is investigated and the relationships and contrasts between concentration quenching of high pigment concentrations, photoprotection (non-photochemical quenching), quenching due to protein aggregation, and fluorescence blinking are discussed. The role of charge-transfer states in light harvesting and energy dissipation is highlighted and the importance of controlled protein structural disorder to switch the light-harvesting antennae between effective light harvesters and efficient energy quenchers is underscored. The main LHC of plants, LHCII, is used as a prime example. (topical review)

  16. The significance of coral reefs as global carbon sinks - response to Greenhouse

    Energy Technology Data Exchange (ETDEWEB)

    Kinsey, D W; Hopley, D [Great Barrier Reef Marine Park Authority, Townsville, Qld. (Australia)

    1991-03-01

    Coral reefs are net sinks for C, principally as CaCO{sub 3} accretion. For the Great Barrier Reef (GBR) net production (G) 1 (kg CaCO{sub 3} m{sup -2} yr{sup -1}) for fringing reefs, G 1.9 for planar (infilled platform) reefs, and G 3 for ribbon reefs and lagoonal reefs is suggested. GBR is estimated to produce approximately 50 million tonnes yr{sup -1}. In a 50-100 year Greenhouse scenario of rising sealevel, recolonisation of present reef flats will be extensive. Production will increase perhaps by {approximately} 40% to give 70 million tonnes yr{sup -1} given a sealevel rise of 6-8 mm yr{sup -1}. An estimated 115,000 km{sup 2} of oceanic atolls worldwide, produce 160 million tonnes yr{sup -1}. A similar increase could be possible. Global reef production, at present {approximately} 900 million tonnes yr{sup -1}, could almost double to within the next 100 years. Long term (several centuries), the trend of recolonisation could result in the production of {gt}3000 million tonnes yr{sup -1} given a sealevel rise of 6-8 mm yr{sup -1}. However, the reefs could 'drown' if the sealevel rise significantly exceeds 6-8 mm yr{sup -1}. Coral reefs are a sink for 111 million tonnes C yr{sup -1}, the equivalent of 2% of anthropogenic CO{sub 2} output. This could increase to {approximately} 4% in the short term (100 years) and {approximately} 9% in the longer term. The immediate effect of CaCO{sub 3} precipitation is to raise the P{sub CO{sub 2}} of the surface oceans, giving a negative value in alleviating Greenhouse effects. Other Greenhouse changes e.g. increases in seawater temperature, and changes in dissolved CO{sub 2} concentration circulation may complicate the reef response. However, during the next 100 years, sealevel rise will be the dominant influence. 45 refs., 1 fig., 4 tabs.

  17. The identification of sites of biodiversity conservation significance: progress with the application of a global standard

    Directory of Open Access Journals (Sweden)

    M.N. Foster

    2012-08-01

    Full Text Available As a global community, we have a responsibility to ensure the long-term future of our natural heritage. As part of this, it is incumbent upon us to do all that we can to reverse the current trend of biodiversity loss, using all available tools at our disposal. One effective mean is safeguarding of those sites that are highest global priority for the conservation of biodiversity, whether through formal protected areas, community managed reserves, multiple-use areas, or other means. This special issue of the Journal of Threatened Taxa examines the application of the Key Biodiversity Area (KBA approach to identifying such sites. Given the global mandate expressed through policy instruments such as the Convention on Biological Diversity (CBD, the KBA approach can help countries meet obligations in an efficient and transparent manner. KBA methodology follows the well-established general principles of vulnerability and irreplaceability, and while it aims to be a globally standardized approach, it recognizes the fundamental need for the process to be led at local and national levels. In this series of papers the application of the KBA approach is explored in seven countries or regions: the Caribbean, Indo-Burma, Japan, Macedonia, Mediterranean Algeria, the Philippines and the Upper Guinea region of West Africa. This introductory article synthesizes some of the common main findings and provides a comparison of key summary statistics.

  18. The regional and global significance of nitrogen removal in lakes and reservoirs

    Science.gov (United States)

    Harrison, J.A.; Maranger, R.J.; Alexander, Richard B.; Giblin, A.E.; Jacinthe, P.-A.; Mayorga, Emilio; Seitzinger, S.P.; Sobota, D.J.; Wollheim, W.M.

    2009-01-01

    Human activities have greatly increased the transport of biologically available nitrogen (N) through watersheds to potentially sensitive coastal ecosystems. Lentic water bodies (lakes and reservoirs) have the potential to act as important sinks for this reactive N as it is transported across the landscape because they offer ideal conditions for N burial in sediments or permanent loss via denitrification. However, the patterns and controls on lentic N removal have not been explored in great detail at large regional to global scales. In this paper we describe, evaluate, and apply a new, spatially explicit, annual-scale, global model of lentic N removal called NiRReLa (Nitrogen Retention in Reservoirs and Lakes). The NiRReLa model incorporates small lakes and reservoirs than have been included in previous global analyses, and also allows for separate treatment and analysis of reservoirs and natural lakes. Model runs for the mid-1990s indicate that lentic systems are indeed important sinks for N and are conservatively estimated to remove 19.7 Tg N year-1 from watersheds globally. Small lakes (<50 km2) were critical in the analysis, retaining almost half (9.3 Tg N year -1) of the global total. In model runs, capacity of lakes and reservoirs to remove watershed N varied substantially at the half-degree scale (0-100%) both as a function of climate and the density of lentic systems. Although reservoirs occupy just 6% of the global lentic surface area, we estimate they retain ~33% of the total N removed by lentic systems, due to a combination of higher drainage ratios (catchment surface area:lake or reservoir surface area), higher apparent settling velocities for N, and greater average N loading rates in reservoirs than in lakes. Finally, a sensitivity analysis of NiRReLa suggests that, on-average, N removal within lentic systems will respond more strongly to changes in land use and N loading than to changes in climate at the global scale. ?? 2008 Springer Science

  19. Significant influences of global mean temperature and ENSO on extreme rainfall over Southeast Asia

    Science.gov (United States)

    Villafuerte, Marcelino, II; Matsumoto, Jun

    2014-05-01

    Along with the increasing concerns on the consequences of global warming, and the accumulating records of disaster related to heavy rainfall events in Southeast Asia, this study investigates whether a direct link can be detected between the rising global mean temperature, as well as the El Niño-Southern Oscillation (ENSO), and extreme rainfall over the region. The maximum likelihood modeling that allows incorporating covariates on the location parameter of the generalized extreme value (GEV) distribution is employed. The GEV model is fitted to annual and seasonal rainfall extremes, which were taken from a high-resolution gauge-based gridded daily precipitation data covering a span of 57 years (1951-2007). Nonstationarities in extreme rainfall are detected over the central parts of Indochina Peninsula, eastern coasts of central Vietnam, northwest of the Sumatra Island, inland portions of Borneo Island, and on the northeastern and southwestern coasts of the Philippines. These nonstationarities in extreme rainfall are directly linked to near-surface global mean temperature and ENSO. In particular, the study reveals that a kelvin increase in global mean temperature anomaly can lead to an increase of 30% to even greater than 45% in annual maximum 1-day rainfall, which were observed pronouncedly over central Vietnam, southern coast of Myanmar, northwestern sections of Thailand, northwestern tip of Sumatra, central portions of Malaysia, and the Visayas island in central Philippines. Furthermore, a pronounced ENSO influence manifested on the seasonal maximum 1-day rainfall; a northward progression of 10%-15% drier condition over Southeast Asia as the El Niño develops from summer to winter is revealed. It is important therefore, to consider the results obtained here for water resources management as well as for adaptation planning to minimize the potential adverse impact of global warming, particularly on extreme rainfall and its associated flood risk over the region

  20. Sensible heat has significantly affected the global hydrological cycle over the historical period.

    Science.gov (United States)

    Myhre, G; Samset, B H; Hodnebrog, Ø; Andrews, T; Boucher, O; Faluvegi, G; Fläschner, D; Forster, P M; Kasoar, M; Kharin, V; Kirkevåg, A; Lamarque, J-F; Olivié, D; Richardson, T B; Shawki, D; Shindell, D; Shine, K P; Stjern, C W; Takemura, T; Voulgarakis, A

    2018-05-15

    Globally, latent heating associated with a change in precipitation is balanced by changes to atmospheric radiative cooling and sensible heat fluxes. Both components can be altered by climate forcing mechanisms and through climate feedbacks, but the impacts of climate forcing and feedbacks on sensible heat fluxes have received much less attention. Here we show, using a range of climate modelling results, that changes in sensible heat are the dominant contributor to the present global-mean precipitation change since preindustrial time, because the radiative impact of forcings and feedbacks approximately compensate. The model results show a dissimilar influence on sensible heat and precipitation from various drivers of climate change. Due to its strong atmospheric absorption, black carbon is found to influence the sensible heat very differently compared to other aerosols and greenhouse gases. Our results indicate that this is likely caused by differences in the impact on the lower tropospheric stability.

  1. Significance of supplier selection criteria evolvment in IT outsourcing to emerging economies: lessons from a global IT outsourcing project

    OpenAIRE

    Hyvonen, H.; Helminen, M.; Watanabe, C.

    2015-01-01

    In line with the increasing significance of the acceleration of information technology (IT) advancement and also of harnessing the vigor of emerging economies, IT outsourcing to emerging economies has become global concerns. This enables global companies to enjoy a critical competitive edge by choosing the best option in outsourcing strategy and supplier selection. Consequently, supplier selection criteria have become critical issues for both suppliers and customers. This paper a...

  2. Prey Preferences of the Snow Leopard (Panthera uncia): Regional Diet Specificity Holds Global Significance for Conservation

    OpenAIRE

    Lyngdoh, Salvador; Shrotriya, Shivam; Goyal, Surendra P.; Clements, Hayley; Hayward, Matthew W.; Habib, Bilal

    2014-01-01

    The endangered snow leopard is a large felid that is distributed over 1.83 million km(2) globally. Throughout its range it relies on a limited number of prey species in some of the most inhospitable landscapes on the planet where high rates of human persecution exist for both predator and prey. We reviewed 14 published and 11 unpublished studies pertaining to snow leopard diet throughout its range. We calculated prey consumption in terms of frequency of occurrence and biomass consumed based o...

  3. Ecological significance of compatible solute accumulation by micro-organisms: from single cells to global climate.

    Science.gov (United States)

    Welsh, D T

    2000-07-01

    The osmoadaptation of most micro-organisms involves the accumulation of K(+) ions and one or more of a restricted range of low molecular mass organic solutes, collectively termed 'compatible solutes'. These solutes are accumulated to high intracellular concentrations, in order to balance the osmotic pressure of the growth medium and maintain cell turgor pressure, which provides the driving force for cell extension growth. In this review, I discuss the alternative roles which compatible solutes may also play as intracellular reserves of carbon, energy and nitrogen, and as more general stress metabolites involved in protection of cells against other environmental stresses including heat, desiccation and freezing. Thus, the evolutionary selection for the accumulation of a specific compatible solute may not depend solely upon its function during osmoadaptation, but also upon the secondary benefits its accumulation provides, such as increased tolerance of other environmental stresses prevalent in the organism's niche or even anti-herbivory or dispersal functions in the case of dimethylsulfoniopropionate (DMSP). In the second part of the review, I discuss the ecological consequences of the release of compatible solutes to the environment, where they can provide sources of compatible solutes, carbon, nitrogen and energy for other members of the micro-flora. Finally, at the global scale the metabolism of specific compatible solutes (betaines and DMSP) in brackish water, marine and hypersaline environments may influence global climate, due to the production of the trace gases, methane and dimethylsulfide (DMS) and in the case of DMS, also couple the marine and terrestrial sulfur cycles.

  4. Photosynthetic Pigments in Diatoms

    OpenAIRE

    Kuczynska, Paulina; Jemiola-Rzeminska, Malgorzata; Strzalka, Kazimierz

    2015-01-01

    Photosynthetic pigments are bioactive compounds of great importance for the food, cosmetic, and pharmaceutical industries. They are not only responsible for capturing solar energy to carry out photosynthesis, but also play a role in photoprotective processes and display antioxidant activity, all of which contribute to effective biomass and oxygen production. Diatoms are organisms of a distinct pigment composition, substantially different from that present in plants. Apart from light-harvestin...

  5. Evolving a photosynthetic organelle

    Directory of Open Access Journals (Sweden)

    Nakayama Takuro

    2012-04-01

    Full Text Available Abstract The evolution of plastids from cyanobacteria is believed to represent a singularity in the history of life. The enigmatic amoeba Paulinella and its 'recently' acquired photosynthetic inclusions provide a fascinating system through which to gain fresh insight into how endosymbionts become organelles. The plastids, or chloroplasts, of algae and plants evolved from cyanobacteria by endosymbiosis. This landmark event conferred on eukaryotes the benefits of photosynthesis - the conversion of solar energy into chemical energy - and in so doing had a huge impact on the course of evolution and the climate of Earth 1. From the present state of plastids, however, it is difficult to trace the evolutionary steps involved in this momentous development, because all modern-day plastids have fully integrated into their hosts. Paulinella chromatophora is a unicellular eukaryote that bears photosynthetic entities called chromatophores that are derived from cyanobacteria and has thus received much attention as a possible example of an organism in the early stages of organellogenesis. Recent studies have unlocked the genomic secrets of its chromatophore 23 and provided concrete evidence that the Paulinella chromatophore is a bona fide photosynthetic organelle 4. The question is how Paulinella can help us to understand the process by which an endosymbiont is converted into an organelle.

  6. Evolving a photosynthetic organelle.

    Science.gov (United States)

    Nakayama, Takuro; Archibald, John M

    2012-04-24

    The evolution of plastids from cyanobacteria is believed to represent a singularity in the history of life. The enigmatic amoeba Paulinella and its 'recently' acquired photosynthetic inclusions provide a fascinating system through which to gain fresh insight into how endosymbionts become organelles.The plastids, or chloroplasts, of algae and plants evolved from cyanobacteria by endosymbiosis. This landmark event conferred on eukaryotes the benefits of photosynthesis--the conversion of solar energy into chemical energy--and in so doing had a huge impact on the course of evolution and the climate of Earth 1. From the present state of plastids, however, it is difficult to trace the evolutionary steps involved in this momentous development, because all modern-day plastids have fully integrated into their hosts. Paulinella chromatophora is a unicellular eukaryote that bears photosynthetic entities called chromatophores that are derived from cyanobacteria and has thus received much attention as a possible example of an organism in the early stages of organellogenesis. Recent studies have unlocked the genomic secrets of its chromatophore 23 and provided concrete evidence that the Paulinella chromatophore is a bona fide photosynthetic organelle 4. The question is how Paulinella can help us to understand the process by which an endosymbiont is converted into an organelle.

  7. Plant communities as drivers of soil respiration: pathways, mechanisms, and significance for global change

    Science.gov (United States)

    Metcalfe, D. B.; Fisher, R. A.; Wardle, D. A.

    2011-03-01

    Understanding the impacts of plant community characteristics on soil carbon dioxide efflux (R) is a key prerequisite for accurate prediction of the future carbon balance of terrestrial ecosystems under climate change. In this review, we synthesize relevant information from a wide spectrum of sources to evaluate the current state of knowledge about plant community effects on R, examine how this information is incorporated into global climate models, and highlight priorities for future research. Plant species consistently exhibit cohesive suites of traits, linked to contrasting life history strategies, which exert a variety of impacts on R. As such, we propose that plant community shifts towards dominance by fast growing plants with nutrient rich litter could provide a major, though often neglected, positive feedback to climate change. Within vegetation types, belowground carbon flux will mainly be controlled by photosynthesis, while amongst vegetation types this flux will be more dependent upon the specific characteristics of the plant life form. We also make the case that community composition, rather than diversity, is usually the dominant control on ecosystem processes in natural systems. Individual species impacts on R may be largest where the species accounts for most of the biomass in the ecosystem, has very distinct traits to the rest of the community, or modulates the occurrence of major natural disturbances. We show that climate-vegetation models incorporate a number of pathways whereby plants can affect R, but that simplifications regarding allocation schemes and drivers of litter decomposition may limit model accuracy. This situation could, however, be relatively easily improved with targeted experimental and field studies. Finally, we identify key gaps in knowledge and recommend them as priorities for future work. These include the patterns of photosynthate partitioning amongst belowground components, ecosystem level effects of individual plant traits

  8. Calculating Clinically Significant Change: Applications of the Clinical Global Impressions (CGI) Scale to Evaluate Client Outcomes in Private Practice

    Science.gov (United States)

    Kelly, Peter James

    2010-01-01

    The Clinical Global Impressions (CGI) scale is a therapist-rated measure of client outcome that has been widely used within the research literature. The current study aimed to develop reliable and clinically significant change indices for the CGI, and to demonstrate its application in private psychological practice. Following the guidelines…

  9. Water Stress in Global Transboundary River Basins: Significance of Upstream Water Use on Downstream Stress

    Science.gov (United States)

    Munia, H.; Guillaume, J. H. A.; Mirumachi, N.; Porkka,M.; Wada, Yoshihide; Kummu, M.

    2016-01-01

    Growing population and water demand have increased pressure on water resources in various parts of the globe, including many transboundary river basins. While the impacts of upstream water use on downstream water availability have been analyzed in many of these international river basins, this has not been systematically done at the global scale using coherent and comparable datasets. In this study, we aim to assess the change in downstream water stress due to upstream water use in the world's transboundary river basins. Water stress was first calculated considering only local water use of each sub-basin based on country-basin mesh, then compared with the situation when upstream water use was subtracted from downstream water availability. Wefound that water stress was generally already high when considering only local water use, affecting 0.95-1.44 billion people or 33%-51% of the population in transboundary river basins. After accounting for upstream water use, stress level increased by at least 1 percentage-point for 30-65 sub-basins, affecting 0.29-1.13 billion people. Altogether 288 out of 298 middle-stream and downstream sub-basin areas experienced some change in stress level. Further, we assessed whether there is a link between increased water stress due to upstream water use and the number of conflictive and cooperative events in the transboundary river basins, as captured by two prominent databases. No direct relationship was found. This supports the argument that conflicts and cooperation events originate from a combination of different drivers, among which upstream-induced water stress may play a role. Our findings contribute to better understanding of upstream-downstream dynamics in water stress to help address water allocation problems.

  10. Significant uncertainty in global scale hydrological modeling from precipitation data erros

    NARCIS (Netherlands)

    Sperna Weiland, F.; Vrugt, J.A.; Beek, van P.H.; Weerts, A.H.; Bierkens, M.F.P.

    2015-01-01

    In the past decades significant progress has been made in the fitting of hydrologic models to data. Most of this work has focused on simple, CPU-efficient, lumped hydrologic models using discharge, water table depth, soil moisture, or tracer data from relatively small river basins. In this paper, we

  11. Significant uncertainty in global scale hydrological modeling from precipitation data errors

    NARCIS (Netherlands)

    Weiland, Frederiek C. Sperna; Vrugt, Jasper A.; van Beek, Rens (L. ) P. H.; Weerts, Albrecht H.; Bierkens, Marc F. P.

    2015-01-01

    In the past decades significant progress has been made in the fitting of hydrologic models to data. Most of this work has focused on simple, CPU-efficient, lumped hydrologic models using discharge, water table depth, soil moisture, or tracer data from relatively small river basins. In this paper, we

  12. Salmonella contamination: a significant challenge to the global marketing of animal food products.

    Science.gov (United States)

    L Plym, Forshell; Wierup, M

    2006-08-01

    Salmonellosis is the most common food-borne bacterial disease in the world. Salmonella is a significant pathogen for food-producing animals and these animals are the primary source of salmonellosis. It is estimated that herd prevalence varies between 0% and 90%, depending on the animal species and region. The pathogen is spread by trade in animals and non-heated animal food products. The emergence of strains that are resistant to antimicrobials, often as a result of antimicrobial usage in animals, is a public health hazard of great concern. It is increasingly accepted that the prevalence of Salmonella in animal production must be decreased and, in the European Union, plans to achieve this are currently being implemented. In this paper, the authors propose various risk mitigation strategies. Successful control must focus on a range of preventive actions because there is no simple 'silver bullet' solution to reduce Salmonella contamination. The authors conclude that the key to controlling Salmonella is to follow the general rules that have been successfully applied to other infectious diseases.

  13. Research on spatial distribution of photosynthetic characteristics of Winter Wheat

    Science.gov (United States)

    Yan, Q. Q.; Zhou, Q. Y.; Zhang, B. Z.; Han, X.; Han, N. N.; Li, S. M.

    2018-03-01

    In order to explore the spatial distribution of photosynthetic characteristics of winter wheat leaf, the photosynthetic rate on different parts of leaf (leaf base-leaf middle-leaf apex) and that on each canopy (top layer-middle layer-bottom layer) leaf during the whole growth period of winter wheat were measured. The variation of photosynthetic rate with PAR and the spatial distribution of winter wheat leaf during the whole growth periods were analysed. The results showed that the photosynthetic rate of different parts of winter wheat increased with the increase of PAR, which was showed as leaf base>leaf middle>leaf apex. In the same growth period, photosynthetic rate in different parts of the tablet was showed as leaf middle>leaf base>leaf apex. For the different canopy layer of winter wheat, the photosynthetic rate of the top layer leaf was significantly greater than that of the middle layer and lower layer leaf. The photosynthetic rate of the top layer leaf was the largest in the leaf base position. The photosynthetic rate of leaf of the same canopy layer at different growth stages were showed as tasseling stage >grain filling stage > maturation stage.

  14. Photoperiodic controls on ecosystem-level photosynthetic capacity

    Science.gov (United States)

    Stoy, P. C.; Trowbridge, A. M.; Bauerle, W.

    2012-12-01

    Most models of photosynthesis at the leaf or canopy level assume that temperature is the dominant control on the variability of photosynthetic parameters. Recent studies, however, have found that photoperiod is a better descriptor of the seasonal variability of photosynthetic function at the leaf and plant scale, and that spectral indices of leaf functionality are poor descriptors of this seasonality. We explored the variability of photosynthesic parameters at the ecosystem scale using over 100 site-years of air temperature and gross primary productivity (GPP) data from non-tropical forested sites in the Free/Fair Use LaThuille FLUXNET database (www.fluxdata.org), excluding sites that were classified as dry and/or with savanna vegetation, where we expected GPP to be driven by moisture availability. Both GPP and GPP normalized by daily photosynthetic photon flux density (GPPn) were considered, and photoperiod was calculated from eddy covariance tower coordinates. We performed a Granger causality analysis, a method based on the understanding that causes precede effects, on both the GPP and GPPn. Photoperiod Granger-caused GPP (GPPn) in 95% (87%) of all site-years. While temperature Granger-caused GPP in a mere 23% of site years, it Granger-caused GPPn 73% of the time. Both temperature values are significantly less than the percent of cases in which day length Granger-caused GPP (p<0.05, Student's t-test). An inverse analysis was performed for completeness, and it was found that GPP Granger-caused photoperiod (temperature) in 39% (78%) of all site years. Results demonstrate that incorporating simple photoperiod controls may be a logical step in improving ecosystem and global model output.

  15. Primary photosynthetic processes: from supercomplex to leaf

    NARCIS (Netherlands)

    Broess, K.

    2009-01-01

    This thesis describes fluorescence spectroscopy experiments on photosynthetic complexes that cover the primary photosynthetic processes, from the absorption of light by photosynthetic pigments to a charge separation (CS) in the reaction center (RC). Fluorescence spectroscopy is a useful tool in

  16. Photosynthetic capacities of mature tropical forest trees in Rwanda are linked to successional group identity rather than to leaf nutrient content

    Science.gov (United States)

    Dusenge, Mirindi Eric; Wallin, Göran; Gårdesten, Johanna; Adolfsson, Lisa; Niyonzima, Felix; Nsabimana, Donat; Uddling, Johan

    2014-05-01

    Tropical forests are crucial in the global carbon balance, yet information required to estimate how much carbon that enter these ecosystems through photosynthesis is very limited, in particular for Africa and for tropical montane forests. In order to increases the knowledge of natural variability of photosynthetic capacities in tropical tree species in tropical Africa, measurements of leaf traits and gas exchange were conducted on sun and shade leaves of ten tree species growing in two tropical forests in Rwanda in central Africa. Seven species were studied in Ruhande Arboretum, a forest plantation at mid altitude (1700 m), and six species in Nyungwe National Park, a cooler and higher altitude (at 2500 m) montane rainforest. Three species were common to both sites. At Nyungwe, three species each belonged to the successional groups pioneer and climax species. Climax species had considerably lower maximum rates of photosynthetic carboxylation (Vcmax) and electron transport (Jmax) than pioneer species. This difference was not related to leaf nutrient content, but rather seemed to be caused by differences in within-leaf N allocation between the two successional groups. With respect to N, leaves of climax species invested less N into photosynthetic enzymes (as judged by lower Vcmax and Jmax values) and more N into chlorophyll (as judged by higher SPAD values). Photosynthetic capacities, (i.e., Jmax and Vcmax), Jmax to Vcmax ratio and P content were significantly higher in Nyungwe than in Arboretum. Sun leaves had higher photosynthetic capacities and nutrient content than shade leaves. Across the entire dataset, variation in photosynthetic capacities among species was not related to leaf nutrient content, although significant relationships were found within individual species. This study contributes critical tropical data for global carbon models and suggests that, for montane rainforest trees of different functional types, successional group identity is a better

  17. Dynamics of photosynthetic activity of cyanobacteria after gut ...

    African Journals Online (AJOL)

    African Journal of Biotechnology ... carp and goldfish, whereas there was a significant stimulation of photosynthetic activity of diatom and green algae following the depressed cyanobacteria during cultivation. The mainly stimulated eukaryotic algae species were Fragilariaceae and Scenedesmus obliquus by microscopy.

  18. Climate controls photosynthetic capacity more than leaf nitrogen contents

    Science.gov (United States)

    Ali, A. A.; Xu, C.; McDowell, N. G.

    2013-12-01

    Global vegetation models continue to lack the ability to make reliable predictions because the photosynthetic capacity varies a lot with growth conditions, season and among species. It is likely that vegetation models link photosynthetic capacity to concurrent changes in leaf nitrogen content only. To improve the predictions of the vegetation models, there is an urgent need to review species growth conditions and their seasonal response to changing climate. We sampled the global distribution of the Vcmax (maximum carboxylation rates) data of various species across different environmental gradients from the literature and standardized its value to 25 degree Celcius. We found that species explained the largest variation in (1) the photosynthetic capacity and (2) the proportion of nitrogen allocated for rubisco (PNcb). Surprisingly, climate variables explained more variations in photosynthetic capacity as well as PNcb than leaf nitrogen content and/or specific leaf area. The chief climate variables that explain variation in photosynthesis and PNcb were radiation, temperature and daylength. Our analysis suggests that species have the greatest control over photosynthesis and PNcb. Further, compared to leaf nitrogen content and/or specific leaf area, climate variables have more control over photosynthesis and PNcb. Therefore, climate variables should be incorporated in the global vegetation models when making predictions about the photosynthetic capacity.

  19. Coral bleaching independent of photosynthetic activity.

    Science.gov (United States)

    Tolleter, Dimitri; Seneca, François O; DeNofrio, Jan C; Krediet, Cory J; Palumbi, Stephen R; Pringle, John R; Grossman, Arthur R

    2013-09-23

    The global decline of reef-building corals is due in part to the loss of algal symbionts, or "bleaching," during the increasingly frequent periods of high seawater temperatures. During bleaching, endosymbiotic dinoflagellate algae (Symbiodinium spp.) either are lost from the animal tissue or lose their photosynthetic pigments, resulting in host mortality if the Symbiodinium populations fail to recover. The >1,000 studies of the causes of heat-induced bleaching have focused overwhelmingly on the consequences of damage to algal photosynthetic processes, and the prevailing model for bleaching invokes a light-dependent generation of toxic reactive oxygen species (ROS) by heat-damaged chloroplasts as the primary trigger. However, the precise mechanisms of bleaching remain unknown, and there is evidence for involvement of multiple cellular processes. In this study, we asked the simple question of whether bleaching can be triggered by heat in the dark, in the absence of photosynthetically derived ROS. We used both the sea anemone model system Aiptasia and several species of reef-building corals to demonstrate that symbiont loss can occur rapidly during heat stress in complete darkness. Furthermore, we observed damage to the photosynthetic apparatus under these conditions in both Aiptasia endosymbionts and cultured Symbiodinium. These results do not directly contradict the view that light-stimulated ROS production is important in bleaching, but they do show that there must be another pathway leading to bleaching. Elucidation of this pathway should help to clarify bleaching mechanisms under the more usual conditions of heat stress in the light. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Photosynthetic fuel for heterologous enzymes

    DEFF Research Database (Denmark)

    Mellor, Silas Busck; Vavitsas, Konstantinos; Nielsen, Agnieszka Janina Zygadlo

    2017-01-01

    of reducing power. Recent work on the metabolic engineering of photosynthetic organisms has shown that the electron carriers such as ferredoxin and flavodoxin can be used to couple heterologous enzymes to photosynthetic reducing power. Because these proteins have a plethora of interaction partners and rely...... on electrostatically steered complex formation, they form productive electron transfer complexes with non-native enzymes. A handful of examples demonstrate channeling of photosynthetic electrons to drive the activity of heterologous enzymes, and these focus mainly on hydrogenases and cytochrome P450s. However......, competition from native pathways and inefficient electron transfer rates present major obstacles, which limit the productivity of heterologous reactions coupled to photosynthesis. We discuss specific approaches to address these bottlenecks and ensure high productivity of such enzymes in a photosynthetic...

  1. Significance of uncertainties derived from settling tank model structure and parameters on predicting WWTP performance - A global sensitivity analysis study

    DEFF Research Database (Denmark)

    Ramin, Elham; Sin, Gürkan; Mikkelsen, Peter Steen

    2011-01-01

    Uncertainty derived from one of the process models – such as one-dimensional secondary settling tank (SST) models – can impact the output of the other process models, e.g., biokinetic (ASM1), as well as the integrated wastewater treatment plant (WWTP) models. The model structure and parameter...... and from the last aerobic bioreactor upstream to the SST (Garrett/hydraulic method). For model structure uncertainty, two one-dimensional secondary settling tank (1-D SST) models are assessed, including a first-order model (the widely used Takács-model), in which the feasibility of using measured...... uncertainty of settler models can therefore propagate, and add to the uncertainties in prediction of any plant performance criteria. Here we present an assessment of the relative significance of secondary settling model performance in WWTP simulations. We perform a global sensitivity analysis (GSA) based...

  2. Non-linear direct effects of acid rain on leaf photosynthetic rate of terrestrial plants.

    Science.gov (United States)

    Dong, Dan; Du, Enzai; Sun, Zhengzhong; Zeng, Xuetong; de Vries, Wim

    2017-12-01

    Anthropogenic emissions of acid precursors have enhanced global occurrence of acid rain, especially in East Asia. Acid rain directly suppresses leaf function by eroding surface waxes and cuticle and leaching base cations from mesophyll cells, while the simultaneous foliar uptake of nitrates in rainwater may directly benefit leaf photosynthesis and plant growth, suggesting a non-linear direct effect of acid rain. By synthesizing data from literature on acid rain exposure experiments, we assessed the direct effects of acid rain on leaf photosynthesis across 49 terrestrial plants in China. Our results show a non-linear direct effect of acid rain on leaf photosynthetic rate, including a neutral to positive effect above pH 5.0 and a negative effect below that pH level. The acid rain sensitivity of leaf photosynthesis showed no significant difference between herbs and woody species below pH 5.0, but the impacts above that pH level were strongly different, resulting in a significant increase in leaf photosynthetic rate of woody species and an insignificant effect on herbs. Our analysis also indicates a positive effect of the molar ratio of nitric versus sulfuric acid in the acid solution on leaf photosynthetic rate. These findings imply that rainwater acidity and the composition of acids both affect the response of leaf photosynthesis and therefore result in a non-linear direct effect. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Cyanobacteria as photosynthetic biocatalysts: a systems biology perspective.

    Science.gov (United States)

    Gudmundsson, Steinn; Nogales, Juan

    2015-01-01

    The increasing need to replace oil-based products and to address global climate change concerns has triggered considerable interest in photosynthetic microorganisms. Cyanobacteria, in particular, have great potential as biocatalysts for fuels and fine-chemicals. During the last few years the biotechnological applications of cyanobacteria have experienced an unprecedented increase and the use of these photosynthetic organisms for chemical production is becoming a tangible reality. However, the field is still immature and many concerns about the economic feasibility of the biotechnological potential of cyanobacteria remain. In this review we describe recent successes in biofuel and fine-chemical production using cyanobacteria. We discuss the role of the photosynthetic metabolism and highlight the need for systems-level metabolic optimization in order to achieve the true potential of cyanobacterial biocatalysts.

  4. Tree Species with Photosynthetic Stems Have Greater Nighttime Sap Flux

    Directory of Open Access Journals (Sweden)

    Xia Chen

    2018-01-01

    Full Text Available An increasing body of evidence has shown that nighttime sap flux occurs in most plants, but the physiological implications and regulatory mechanism are poorly known. The significance of corticular photosynthesis has received much attention during the last decade, however, the knowledge of the relationship between corticular photosynthesis and nocturnal stem sap flow is limited at present. In this study, we divided seven tree species into two groups according to different photosynthetic capabilities: trees of species with (Castanopsis hystrix, Michelia macclurei, Eucalyptus citriodora, and Eucalyptus grandis × urophylla and without (Castanopsis fissa, Schima superba, and Acacia auriculiformis photosynthetic stems, and the sap flux (Js and chlorophyll fluorescence parameters for these species were measured. One-way ANOVA analysis showed that the Fv/Fm (Maximum photochemical quantum yield of PSII and ΦPSII (effective photochemical quantum yield of PSII values were lower in non-photosynthetic stem species compared to photosynthetic stem species. The linear regression analysis showed that Js,d (daytime sap flux and Js,n (nighttime sap flux of non-photosynthetic stem species was 87.7 and 60.9% of the stem photosynthetic species. Furthermore, for a given daytime transpiration water loss, total nighttime sap flux was higher in species with photosynthetic stems (SlopeSMA = 2.680 than in non-photosynthetic stems species (SlopeSMA = 1.943. These results mean that stem corticular photosynthesis has a possible effect on the nighttime water flow, highlighting the important eco-physiological relationship between nighttime sap flux and corticular photosynthesis.

  5. Tree Species with Photosynthetic Stems Have Greater Nighttime Sap Flux.

    Science.gov (United States)

    Chen, Xia; Gao, Jianguo; Zhao, Ping; McCarthy, Heather R; Zhu, Liwei; Ni, Guangyan; Ouyang, Lei

    2018-01-01

    An increasing body of evidence has shown that nighttime sap flux occurs in most plants, but the physiological implications and regulatory mechanism are poorly known. The significance of corticular photosynthesis has received much attention during the last decade, however, the knowledge of the relationship between corticular photosynthesis and nocturnal stem sap flow is limited at present. In this study, we divided seven tree species into two groups according to different photosynthetic capabilities: trees of species with ( Castanopsis hystrix, Michelia macclurei, Eucalyptus citriodora , and Eucalyptus grandis × urophylla ) and without ( Castanopsis fissa, Schima superba , and Acacia auriculiformis ) photosynthetic stems, and the sap flux ( J s ) and chlorophyll fluorescence parameters for these species were measured. One-way ANOVA analysis showed that the F v / F m (Maximum photochemical quantum yield of PSII) and Φ PSII (effective photochemical quantum yield of PSII) values were lower in non-photosynthetic stem species compared to photosynthetic stem species. The linear regression analysis showed that J s,d (daytime sap flux) and J s,n (nighttime sap flux) of non-photosynthetic stem species was 87.7 and 60.9% of the stem photosynthetic species. Furthermore, for a given daytime transpiration water loss, total nighttime sap flux was higher in species with photosynthetic stems (Slope SMA = 2.680) than in non-photosynthetic stems species (Slope SMA = 1.943). These results mean that stem corticular photosynthesis has a possible effect on the nighttime water flow, highlighting the important eco-physiological relationship between nighttime sap flux and corticular photosynthesis.

  6. Tree Species with Photosynthetic Stems Have Greater Nighttime Sap Flux

    Science.gov (United States)

    Chen, Xia; Gao, Jianguo; Zhao, Ping; McCarthy, Heather R.; Zhu, Liwei; Ni, Guangyan; Ouyang, Lei

    2018-01-01

    An increasing body of evidence has shown that nighttime sap flux occurs in most plants, but the physiological implications and regulatory mechanism are poorly known. The significance of corticular photosynthesis has received much attention during the last decade, however, the knowledge of the relationship between corticular photosynthesis and nocturnal stem sap flow is limited at present. In this study, we divided seven tree species into two groups according to different photosynthetic capabilities: trees of species with (Castanopsis hystrix, Michelia macclurei, Eucalyptus citriodora, and Eucalyptus grandis × urophylla) and without (Castanopsis fissa, Schima superba, and Acacia auriculiformis) photosynthetic stems, and the sap flux (Js) and chlorophyll fluorescence parameters for these species were measured. One-way ANOVA analysis showed that the Fv/Fm (Maximum photochemical quantum yield of PSII) and ΦPSII (effective photochemical quantum yield of PSII) values were lower in non-photosynthetic stem species compared to photosynthetic stem species. The linear regression analysis showed that Js,d (daytime sap flux) and Js,n (nighttime sap flux) of non-photosynthetic stem species was 87.7 and 60.9% of the stem photosynthetic species. Furthermore, for a given daytime transpiration water loss, total nighttime sap flux was higher in species with photosynthetic stems (SlopeSMA = 2.680) than in non-photosynthetic stems species (SlopeSMA = 1.943). These results mean that stem corticular photosynthesis has a possible effect on the nighttime water flow, highlighting the important eco-physiological relationship between nighttime sap flux and corticular photosynthesis. PMID:29416547

  7. Progress in Remote Sensing of Photosynthetic Activity over the Amazon Basin

    Science.gov (United States)

    Resende de Sousa, Celio Helder; Hilker, Thomas; Waring, Richard; Mendes De Moura, Yhasmin; Lyapustin, Alexei

    2017-01-01

    Although quantifying the massive exchange of carbon that takes place over the Amazon Basin remains a challenge, progress is being made as the remote sensing community moves from using traditional, reflectance-based vegetation indices, such as the Normalized Difference Vegetation Index (NDVI), to the more functional Photochemical Reflectance Index (PRI). This new index, together with satellite-derived estimates of canopy light interception and Sun-Induced Fluorescence (SIF), provide improved estimates of Gross Primary Production (GPP). This paper traces the development of these new approaches, compares the results of their analyses from multiple years of data acquired across the Amazon Basin and suggests further improvements in instrument design, data acquisition and processing. We demonstrated that our estimates of PRI are in generally good agreement with eddy-flux tower measurements of photosynthetic light use efficiency (epsilon) at four sites in the Amazon Basin: r(exp 2) values ranged from 0.37 to 0.51 for northern flux sites and to 0.78for southern flux sites. This is a significant advance over previous approaches seeking to establish a link between global-scale photosynthetic activity and remotely-sensed data. When combined with measurements of Sun-Induced Fluorescence (SIF), PRI provides realistic estimates of seasonal variation in photosynthesis over the Amazon that relate well to the wet and dry seasons. We anticipate that our findings will steer the development of improved approaches to estimate photosynthetic activity over the tropics.

  8. Rice Photosynthetic Productivity and PSII Photochemistry under Nonflooded Irrigation

    Directory of Open Access Journals (Sweden)

    Haibing He

    2014-01-01

    Full Text Available Nonflooded irrigation is an important water-saving rice cultivation technology, but little is known on its photosynthetic mechanism. The aims of this work were to investigate photosynthetic characteristics of rice during grain filling stage under three nonflooded irrigation treatments: furrow irrigation with plastic mulching (FIM, furrow irrigation with nonmulching (FIN, and drip irrigation with plastic mulching (DI. Compared with the conventional flooding (CF treatment, those grown in the nonflooded irrigation treatments showed lower net photosynthetic rate (PN, lower maximum quantum yield (Fv/Fm, and lower effective quantum yield of PSII photochemistry (ΦPSII. And the poor photosynthetic characteristics in the nonflooded irrigation treatments were mainly attributed to the low total nitrogen content (TNC. Under non-flooded irrigation, the PN, Fv/Fm, and ΦPSII significantly decreased with a reduction in the soil water potential, but these parameters were rapidly recovered in the DI and FIM treatments when supplementary irrigation was applied. Moreover, The DI treatment always had higher photosynthetic productivity than the FIM and FIN treatments. Grain yield, matter translocation, and dry matter post-anthesis (DMPA were the highest in the CF treatment, followed by the DI, FIM, and FIN treatments in turn. In conclusion, increasing nitrogen content in leaf of rice plants could be a key factor to improve photosynthetic capacity in nonflooded irrigation.

  9. Continuing global significance of emissions of Montreal Protocol-restricted halocarbons in the United States and Canada

    Science.gov (United States)

    Hurst, D. F.; Lin, J. C.; Romashkin, P. A.; Daube, B. C.; Gerbig, C.; Matross, D. M.; Wofsy, S. C.; Hall, B. D.; Elkins, J. W.

    2006-08-01

    Contemporary emissions of six restricted, ozone-depleting halocarbons, chlorofluorocarbon-11 (CFC-11, CCl3F), CFC-12 (CCl2F2), CFC-113 (CCl2FCClF2), methyl chloroform (CH3CCl3), carbon tetrachloride (CCl4), and Halon-1211 (CBrClF2), and two nonregulated trace gases, chloroform (CHCl3) and sulfur hexafluoride (SF6), are estimated for the United States and Canada. The estimates derive from 900 to 2900 in situ measurements of each of these gases within and above the planetary boundary layer over the United States and Canada as part of the 2003 CO2 Budget and Regional Airborne-North America (COBRA-NA) study. Air masses polluted by anthropogenic sources, identified by concurrently elevated levels of carbon monoxide (CO), SF6, and CHCl3, were sampled over a wide geographical range of these two countries. For each polluted air mass, we calculated emission ratios of halocarbons to CO and employed the Stochastic Time-Inverted Lagrangian Transport (STILT) model to determine the footprint associated with the air mass. Gridded CO emission estimates were then mapped onto the footprints and combined with measured emission ratios to generate footprint-weighted halocarbon flux estimates. We present statistically significant linear relationships between halocarbon fluxes (excluding CCl4) and footprint-weighted population densities, with slopes representative of per capita emission rates. These rates indicate that contemporary emissions of five restricted halocarbons (excluding CCl4) in the United States and Canada continue to account for significant fractions (7-40%) of global emissions.

  10. Photosynthetic performance of restored and natural mangroves under different environmental constraints

    International Nuclear Information System (INIS)

    Rovai, André Scarlate; Barufi, José Bonomi; Pagliosa, Paulo Roberto; Scherner, Fernando; Torres, Moacir Aluísio; Horta, Paulo Antunes

    2013-01-01

    We hypothesized that the photosynthetic performance of mangrove stands restored by the single planting of mangroves species would be lowered due to residual stressors. The photosynthetic parameters of the vegetation of three planted mangrove stands, each with a different disturbance history, were compared to reference sites and correlated with edaphic environmental variables. A permutational analysis of variance showed significant interaction when the factors were compared, indicating that the photosynthetic parameters of the restoration areas differed from the reference sites. A univariate analysis of variance showed that all the photosynthetic parameters differed between sites and treatments, except for photosynthetic efficiency (α ETR ). The combination of environmental variables that best explained the variations observed in the photosynthetic performance indicators were Cu, Pb and elevation disruptions. Fluorescence techniques proved efficient in revealing important physiological differences, representing a powerful tool for rapid analysis of the effectiveness of initiatives aimed at restoring coastal environments. -- Highlights: •Photosynthetic efficiency of natural and restored mangroves are compared. •Natural stands present higher photosynthetic performance. •Photosynthetic performance of mangroves is reduced due to Cu and Pb contamination. •Chlorophyll a fluorescence is a useful indicator to assess short-term restoration. -- Photosynthetic performance of mangroves is reduced due to Cu and Pb contamination

  11. Photosynthetic performance of restored and natural mangroves under different environmental constraints

    Energy Technology Data Exchange (ETDEWEB)

    Rovai, André Scarlate, E-mail: rovaias@hotmail.com [Universidade Federal de Santa Catarina, Departamento de Ecologia e Zoologia, Campus Universitário, Trindade, 88040-900 Florianópolis, SC (Brazil); Barufi, José Bonomi, E-mail: jose.bonomi@gmail.com [Universidade Federal de Santa Catarina, Departamento de Botânica, Campus Universitário, Trindade, 88040-900 Florianópolis, SC (Brazil); Pagliosa, Paulo Roberto, E-mail: paulo.pagliosa@ufsc.br [Universidade Federal de Santa Catarina, Departamento de Geociências, Campus Universitário, Trindade, 88040-900 Florianópolis, SC (Brazil); Scherner, Fernando [Universidade Federal Rural de Pernambuco, Laboratório de Ficologia, Campus Universitário, Dois Irmãos, 52171-900 Recife, PE (Brazil); Torres, Moacir Aluísio, E-mail: moatorres@cav.udesc.br [Universidade do Estado de Santa Catarina, Departamento de Engenharia Ambiental, Centro de Ciências Agroveterinárias, Av Luiz de Camões 2090, Conta Dinheiro, 88520-000 Lages, SC (Brazil); Horta, Paulo Antunes, E-mail: pahorta@ccb.ufsc.br [Universidade Federal de Santa Catarina, Departamento de Botânica, Campus Universitário, Trindade, 88040-900 Florianópolis, SC (Brazil); others, and

    2013-10-15

    We hypothesized that the photosynthetic performance of mangrove stands restored by the single planting of mangroves species would be lowered due to residual stressors. The photosynthetic parameters of the vegetation of three planted mangrove stands, each with a different disturbance history, were compared to reference sites and correlated with edaphic environmental variables. A permutational analysis of variance showed significant interaction when the factors were compared, indicating that the photosynthetic parameters of the restoration areas differed from the reference sites. A univariate analysis of variance showed that all the photosynthetic parameters differed between sites and treatments, except for photosynthetic efficiency (α{sub ETR}). The combination of environmental variables that best explained the variations observed in the photosynthetic performance indicators were Cu, Pb and elevation disruptions. Fluorescence techniques proved efficient in revealing important physiological differences, representing a powerful tool for rapid analysis of the effectiveness of initiatives aimed at restoring coastal environments. -- Highlights: •Photosynthetic efficiency of natural and restored mangroves are compared. •Natural stands present higher photosynthetic performance. •Photosynthetic performance of mangroves is reduced due to Cu and Pb contamination. •Chlorophyll a fluorescence is a useful indicator to assess short-term restoration. -- Photosynthetic performance of mangroves is reduced due to Cu and Pb contamination.

  12. Biogeography of photosynthetic light-harvesting genes in marine phytoplankton.

    Directory of Open Access Journals (Sweden)

    Thomas S Bibby

    Full Text Available BACKGROUND: Photosynthetic light-harvesting proteins are the mechanism by which energy enters the marine ecosystem. The dominant prokaryotic photoautotrophs are the cyanobacterial genera Prochlorococcus and Synechococcus that are defined by two distinct light-harvesting systems, chlorophyll-bound protein complexes or phycobilin-bound protein complexes, respectively. Here, we use the Global Ocean Sampling (GOS Project as a unique and powerful tool to analyze the environmental diversity of photosynthetic light-harvesting genes in relation to available metadata including geographical location and physical and chemical environmental parameters. METHODS: All light-harvesting gene fragments and their metadata were obtained from the GOS database, aligned using ClustalX and classified phylogenetically. Each sequence has a name indicative of its geographic location; subsequent biogeographical analysis was performed by correlating light-harvesting gene budgets for each GOS station with surface chlorophyll concentration. CONCLUSION/SIGNIFICANCE: Using the GOS data, we have mapped the biogeography of light-harvesting genes in marine cyanobacteria on ocean-basin scales and show that an environmental gradient exists in which chlorophyll concentration is correlated to diversity of light-harvesting systems. Three functionally distinct types of light-harvesting genes are defined: (1 the phycobilisome (PBS genes of Synechococcus; (2 the pcb genes of Prochlorococcus; and (3 the iron-stress-induced (isiA genes present in some marine Synechococcus. At low chlorophyll concentrations, where nutrients are limited, the Pcb-type light-harvesting system shows greater genetic diversity; whereas at high chlorophyll concentrations, where nutrients are abundant, the PBS-type light-harvesting system shows higher genetic diversity. We interpret this as an environmental selection of specific photosynthetic strategy. Importantly, the unique light-harvesting system isiA is found

  13. Special issue of photosynthetic research

    NARCIS (Netherlands)

    Okamura, M.; Wraight, C.A.; van Grondelle, R.

    2014-01-01

    This Special Issue of Photosynthesis Research honors Louis M. N. Duysens, Roderick K. Clayton, and George Feher, three pioneering researchers whose work on bacterial photosynthesis laid much of the groundwork for our understanding of the role of the reaction center in photosynthetic light energy

  14. Photosynthetic performance of restored and natural mangroves under different environmental constraints.

    Science.gov (United States)

    Rovai, André Scarlate; Barufi, José Bonomi; Pagliosa, Paulo Roberto; Scherner, Fernando; Torres, Moacir Aluísio; Horta, Paulo Antunes; Simonassi, José Carlos; Quadros, Daiane Paula Cunha; Borges, Daniel Lázaro Gallindo; Soriano-Sierra, Eduardo Juan

    2013-10-01

    We hypothesized that the photosynthetic performance of mangrove stands restored by the single planting of mangroves species would be lowered due to residual stressors. The photosynthetic parameters of the vegetation of three planted mangrove stands, each with a different disturbance history, were compared to reference sites and correlated with edaphic environmental variables. A permutational analysis of variance showed significant interaction when the factors were compared, indicating that the photosynthetic parameters of the restoration areas differed from the reference sites. A univariate analysis of variance showed that all the photosynthetic parameters differed between sites and treatments, except for photosynthetic efficiency (αETR). The combination of environmental variables that best explained the variations observed in the photosynthetic performance indicators were Cu, Pb and elevation disruptions. Fluorescence techniques proved efficient in revealing important physiological differences, representing a powerful tool for rapid analysis of the effectiveness of initiatives aimed at restoring coastal environments. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Photosynthetic characteristics of Lycoris aurea and monthly ...

    African Journals Online (AJOL)

    The leaf photosynthetic characteristics of Lycoris aurea, the monthly dynamics in lycorine and galantamine contents in its bulb and the correlation among the photosynthetic characteristics and the lycorine and galantamine during the annual growth period were studied by using LI-6400 portable photosynthetic measurement ...

  16. Globalization

    Directory of Open Access Journals (Sweden)

    Tulio Rosembuj

    2006-12-01

    Full Text Available There is no singular globalization, nor is the result of an individual agent. We could start by saying that global action has different angles and subjects who perform it are different, as well as its objectives. The global is an invisible invasion of materials and immediate effects.

  17. Globalization

    OpenAIRE

    Tulio Rosembuj

    2006-01-01

    There is no singular globalization, nor is the result of an individual agent. We could start by saying that global action has different angles and subjects who perform it are different, as well as its objectives. The global is an invisible invasion of materials and immediate effects.

  18. Global significance of a sub-Moho boundary layer (SMBL) deduced from high-resolution seismic observations

    Science.gov (United States)

    Fuchs, K.; Tittgemeyer, M.; Ryberg, T.; Wenzel, F.; Mooney, W.

    2002-01-01

    We infer the fine structure of a sub-Moho boundary layer (SMBL) at the top of the lithospheric mantle from high-resolution seismic observations of Peaceful Nuclear Explosions (PNE) on superlong-range profiles in Russia. Densely recorded seismograms permit recognition of previously unknown features of teleseismic propagation of the well known Pn and Sn phases, such as a band of incoherent, scattered, high-frequency seismic energy, developing consistently from station to station, apparent velocities of sub-Moho material, and high-frequency energy to distances of more than 3000 km with a coda band, incoherent at 10 km spacing and yet consistently observed to the end of the profiles. Estimates of the other key elements of the SMBL were obtained by finite difference calculations of wave propagation in elastic 2D models from a systematic grid search through parameter space. The SMBL consists of randomly distributed, mild velocity fluctuations of 2% or schlieren of high aspect ratios (???40) with long horizontal extent (???20 km) and therefore as thin as 0.5 km only; SMBL thickness is 60-100 km. It is suggested that the SMBL is of global significance as the physical base of the platewide observed high-frequency phases Pn and Sn. It is shown that wave propagation in the SMBL waveguide is insensitive to the background velocity distribution on which its schlieren are superimposed. This explains why the Pn and Sn phases traverse geological provinces of various age, heat flow, crustal thickness, and tectonic regimes. Their propagation appears to be independent of age. temperature, pressure, and stress. Dynamic stretching of mantle material during subduction or flow, possibly combined with chemical differentiation have to be considered as scale-forming processes in the upper mantle. However, it is difficult to distinguish with the present sets of Pn/Sn array data whether (and also where) the boundary layer is a frozen-in feature of paleo-processes or whether it is a response to

  19. Does the correlation between solar cycle lengths and Northern Hemisphere land temperatures rule out any significant global warming from greenhouse gases?

    DEFF Research Database (Denmark)

    Laut, Peter; Gundermann, Jesper

    1998-01-01

    Since the discovery of a striking correlation between solar cycle lengths and Northern Hemisphere land temperatures there have been widespread speculations as to whether these findings would rule out any significant contributions to global warming from the enhanced concentrations of greenhouse...... gases. The present analysis shows that a similar degree of correlation is obtained when testing the solar data against a couple of fictitious temperature series representing different global warming trends. Therefore, the correlation cannot be used to estimate the magnitude of a possible contribution...... to global warming from human activities, nor to rule out a sizable contribution from that source....

  20. Practical ways to abate air and water pollution worldwide including a unique way to significantly curb global warming

    Energy Technology Data Exchange (ETDEWEB)

    Snell, J.R.

    1998-07-01

    This paper points out that in the next 50 years it will largely be the developing countries of the world which will continue to industrialize rapidly and hence pollute the water and air of not only their countries but that this pollution is becoming global (80% of the World's population.) From the author's 25 years of consulting experience in the developing countries, their greatest need is to have available to them low cost, innovative processes for pollution abatement will be neglected and the whole world will suffer immensely. The paper discusses in some detail the type of innovative low cost methods which have successfully been used in the categories of wastewater and solid wastes and names 6 other categories where many others exist. All these innovative methods need to be discovered, listed, and tested for quality and dependability, and then made widely available. Large Environmental Engineering Universities and International Consulting Engineering firms need to be organized to undertake these important tasks. The paper also points out the connection between Global Warming and the Solid waste industry and shows how it can be controlled inexpensively by employing a new, unique, and rapid method of converting municipal refuse into methane and then using that to make electricity. Information given in this paper could lead to a vast reduction in future pollution, with the resulting better global health and at the same time save trillions of dollars.

  1. U.S. Geological Survey assessment of global potash production and resources—A significant advancement for global development and a sustainable future.

    Science.gov (United States)

    Cocker, Mark D.; Orris, Greta J.; Wynn, Jeff

    2016-01-01

    During the past 15 yr, the global requirement for fertilizers has grown considerably, mainly due to demand by a larger and wealthier world population for more and higher-quality food. The demand and price for potash as a primary fertilizer ingredient have increased in tandem, because of the necessity to increase the quantity and quality of food production on the decreasing amount of available arable land. The primary sources of potash are evaporates, which occur mainly in marine salt basins and a few brine-bearing continental basins. World potash resources are large, but distribution is inequitable and not presently developed in countries where population and food requirements are large and increasing. There is no known substitute for potash in fertilizer, so knowledge of the world’s potash resources is critical for a sustainable future. The U.S. Geological Survey recently completed a global assessment of evaporite-hosted potash resources, which included a geographic information system–based inventory of known potash resources. This assessment included permissive areas or tracts for undiscovered resources at a scale of 1:1,000,000. Assessments of undiscovered potash resources were conducted for a number of the world’s evaporite-hosted potash basins. The data collected provide a major advance in our knowledge of global potash resources that did not exist prior to this study. The two databases include: (1) potash deposits and occurrences, and (2) potash tracts (basins that contain these deposits and occurrences and potentially undiscovered potash deposits). Data available include geology, mineralogy, grade, tonnage, depth, thickness, areal extent, and structure, as well as numerous pertinent references.

  2. Globalization

    OpenAIRE

    Andru?cã Maria Carmen

    2013-01-01

    The field of globalization has highlighted an interdependence implied by a more harmonious understanding determined by the daily interaction between nations through the inducement of peace and the management of streamlining and the effectiveness of the global economy. For the functioning of the globalization, the developing countries that can be helped by the developed ones must be involved. The international community can contribute to the institution of the development environment of the gl...

  3. Variabilidade sazonal da relação entre a radiação fotossinteticamente ativa e a radiação global na bacia do rio Doce, Estado de Minas Gerais = Seasonal variability of the relationship between the photosynthetically active radiation and the global radiation at the river Doce basin, Minas Gerais State

    Directory of Open Access Journals (Sweden)

    Antonio José Steidle Neto

    2006-07-01

    Full Text Available O conhecimento da Radiação Fotossinteticamente Ativa (RFA é importante para diferentes áreas relacionadas à fisiologia vegetal e ciências agrárias. Modelos de estimativa de RFA a partir da Radiação Global (Rg são extremamente úteis, visto que a Rg é convencionalmente medida nas estações meteorológicas. Assim, analisou-se a variabilidade sazonal da relação RFA/Rg em cinco áreas localizadas na bacia do rio Doce, Estado de Minas Gerais, considerando-se os períodos secos e chuvosos dos anos de 2001 a 2004. As relações RFA/Rg obtidas para os períodos secos e chuvosos, assim como para todos os dados, apresentaram concordância com as relações determinadas por diversos pesquisadores em diferentes áreas do mundo. Analisando-se os resultados, constatou-se que, de maneira geral,as relações RFA/Rg tendem a ser superiores durante os períodos chuvosos comparativamente aos secos. Por este estudo, pôde-se concluir que existe variação interanual desta relação, demonstrando assim a necessidade de se considerar esta variabilidade para estimaradequadamente a RFA a partir da Rg. The knowledge of the Photosynthetically Active Radiation (PAR is important to different areas of vegetal physiology and agricultural sciences. Estimation models of the PAR based on the Global Radiation (GR are extremely useful, since the GR is conventionally measured atthe meteorological stations. Thus, the seasonal variability of the relationship PAR/GR was analyzed in five areas located at the river Doce basin, Minas Gerais State, Brazil, considering the dry and wet periods of the years 2001 to 2004. The relationships PAR/GR obtained for the dry and wet periods, and also to all data, presented agreement with those ones determined by several researchers in different areas of the world. Results showed that the relationshipsPAR/GR generally tend to be greater during the wet periods when compared with the dry ones. By this work, it could be concluded that

  4. A remotely sensed pigment index reveals photosynthetic phenology in evergreen conifers

    OpenAIRE

    Gamon, John A.

    2016-01-01

    In evergreen conifers, where the foliage amount changes little with season, accurate detection of the underlying “photosynthetic phenology” from satellite remote sensing has been difficult, presenting challenges for global models of ecosystem carbon uptake. Here, we report a close correspondence between seasonally changing foliar pigment levels, expressed as chlorophyll/carotenoid ratios, and evergreen photosynthetic activity, leading to a “chlorophyll/carotenoid index” (CCI) that tracks ever...

  5. [[The global significance of the Cairo conference: the new program of action of the International Conference on Population and Development

    Science.gov (United States)

    Atoh, M

    1994-10-01

    "The [1994] International Conference on Population and Development was held in Cairo, Egypt.... In this essay I briefly described global population trends and [their] economic and ecological implications, stated the temporal progress from arguments in the three Preparatory Committees toward the achievement of consensus at the end of the Cairo Conference, summarized and commented [on] each chapter of the Programme of Action, clarified the major characteristics of the Cairo document compared to the documents in Bucharest and Mexico City, and finally discussed the effectiveness of the strategy suggested in the Cairo document for addressing population and development issues in the context of sustainability." (SUMMARY IN ENG) excerpt

  6. Energy transfer in real and artificial photosynthetic systems

    Energy Technology Data Exchange (ETDEWEB)

    Hindman, J.C.; Hunt, J.E.; Katz, J.J.

    1995-02-01

    Fluorescence emission from the photosynthetic organisms Tribonema aequale, Anacystis nidulau, and Chlorelia vulgais and from some chlorophyll model systems have been recorded as a function of excitation wavelength and temperature. Considerable similarity was observed in the effects of excitation wavelength and temperature on the fluorescence from intact photosynthetic organisms and the model systems. The parallelism in behavior suggest that self-assembly processes may occur in both the in vivo and in vitro systems that give rise to chlorophyll species at low temperature that may differ significantly from those present at ambient temperatures.

  7. Primates in peril: the significance of Brazil, Madagascar, Indonesia and the Democratic Republic of the Congo for global primate conservation

    Science.gov (United States)

    Mittermeier, Russell A.; Wich, Serge; Gouveia, Sidney; Dobrovolski, Ricardo; Nijman, Vincent; Rylands, Anthony B.; Johnson, Steig; Rodrigues de Melo, Fabiano; Schwitzer, Christoph; Roos, Christian; Cheyne, Susan M.; Martins Kierulff, Maria Cecilia; Raharivololona, Brigitte; Ratsimbazafy, Jonah; Supriatna, Jatna; Boonratana, Ramesh; Wedana, Made; Setiawan, Arif

    2018-01-01

    Primates occur in 90 countries, but four—Brazil, Madagascar, Indonesia, and the Democratic Republic of the Congo (DRC)—harbor 65% of the world’s primate species (439) and 60% of these primates are Threatened, Endangered, or Critically Endangered (IUCN Red List of Threatened Species 2017-3). Considering their importance for global primate conservation, we examine the anthropogenic pressures each country is facing that place their primate populations at risk. Habitat loss and fragmentation are main threats to primates in Brazil, Madagascar, and Indonesia. However, in DRC hunting for the commercial bushmeat trade is the primary threat. Encroachment on primate habitats driven by local and global market demands for food and non-food commodities hunting, illegal trade, the proliferation of invasive species, and human and domestic-animal borne infectious diseases cause habitat loss, population declines, and extirpation. Modeling agricultural expansion in the 21st century for the four countries under a worst-case-scenario, showed a primate range contraction of 78% for Brazil, 72% for Indonesia, 62% for Madagascar, and 32% for DRC. These pressures unfold in the context of expanding human populations with low levels of development. Weak governance across these four countries may limit effective primate conservation planning. We examine landscape and local approaches to effective primate conservation policies and assess the distribution of protected areas and primates in each country. Primates in Brazil and Madagascar have 38% of their range inside protected areas, 17% in Indonesia and 14% in DRC, suggesting that the great majority of primate populations remain vulnerable. We list the key challenges faced by the four countries to avert primate extinctions now and in the future. In the short term, effective law enforcement to stop illegal hunting and illegal forest destruction is absolutely key. Long-term success can only be achieved by focusing local and global public

  8. Primates in peril: the significance of Brazil, Madagascar, Indonesia and the Democratic Republic of the Congo for global primate conservation.

    Science.gov (United States)

    Estrada, Alejandro; Garber, Paul A; Mittermeier, Russell A; Wich, Serge; Gouveia, Sidney; Dobrovolski, Ricardo; Nekaris, K A I; Nijman, Vincent; Rylands, Anthony B; Maisels, Fiona; Williamson, Elizabeth A; Bicca-Marques, Julio; Fuentes, Agustin; Jerusalinsky, Leandro; Johnson, Steig; Rodrigues de Melo, Fabiano; Oliveira, Leonardo; Schwitzer, Christoph; Roos, Christian; Cheyne, Susan M; Martins Kierulff, Maria Cecilia; Raharivololona, Brigitte; Talebi, Mauricio; Ratsimbazafy, Jonah; Supriatna, Jatna; Boonratana, Ramesh; Wedana, Made; Setiawan, Arif

    2018-01-01

    Primates occur in 90 countries, but four-Brazil, Madagascar, Indonesia, and the Democratic Republic of the Congo (DRC)-harbor 65% of the world's primate species (439) and 60% of these primates are Threatened, Endangered, or Critically Endangered (IUCN Red List of Threatened Species 2017-3). Considering their importance for global primate conservation, we examine the anthropogenic pressures each country is facing that place their primate populations at risk. Habitat loss and fragmentation are main threats to primates in Brazil, Madagascar, and Indonesia. However, in DRC hunting for the commercial bushmeat trade is the primary threat. Encroachment on primate habitats driven by local and global market demands for food and non-food commodities hunting, illegal trade, the proliferation of invasive species, and human and domestic-animal borne infectious diseases cause habitat loss, population declines, and extirpation. Modeling agricultural expansion in the 21st century for the four countries under a worst-case-scenario, showed a primate range contraction of 78% for Brazil, 72% for Indonesia, 62% for Madagascar, and 32% for DRC. These pressures unfold in the context of expanding human populations with low levels of development. Weak governance across these four countries may limit effective primate conservation planning. We examine landscape and local approaches to effective primate conservation policies and assess the distribution of protected areas and primates in each country. Primates in Brazil and Madagascar have 38% of their range inside protected areas, 17% in Indonesia and 14% in DRC, suggesting that the great majority of primate populations remain vulnerable. We list the key challenges faced by the four countries to avert primate extinctions now and in the future. In the short term, effective law enforcement to stop illegal hunting and illegal forest destruction is absolutely key. Long-term success can only be achieved by focusing local and global public

  9. Effect of ambient levels of ozone on photosynthetic components and ...

    African Journals Online (AJOL)

    Effect of ambient levels of ozone on photosynthetic components and radical scavenging system in leaves of African cowpea varieties. ... The O3-induced significant reduction in catalase activity was observed in Blackeye at vegetative and reproductive growth stages; and in Asontem at reproductive growth stage. On the other ...

  10. Photosynthetic oxygen production in a warmer ocean: the Sargasso Sea as a case study.

    Science.gov (United States)

    Richardson, Katherine; Bendtsen, Jørgen

    2017-09-13

    Photosynthetic O 2 production can be an important source of oxygen in sub-surface ocean waters especially in permanently stratified oligotrophic regions of the ocean where O 2 produced in deep chlorophyll maxima (DCM) is not likely to be outgassed. Today, permanently stratified regions extend across approximately 40% of the global ocean and their extent is expected to increase in a warmer ocean. Thus, predicting future ocean oxygen conditions requires a better understanding of the potential response of photosynthetic oxygen production to a warmer ocean. Based on our own and published observations of water column processes in oligotrophic regions, we develop a one-dimensional water column model describing photosynthetic oxygen production in the Sargasso Sea to quantify the importance of photosynthesis for the downward flux of O 2 and examine how it may be influenced in a warmer ocean. Photosynthesis is driven in the model by vertical mixing of nutrients (including eddy-induced mixing) and diazotrophy and is found to substantially increase the downward O 2 flux relative to physical-chemical processes alone. Warming (2°C) surface waters does not significantly change oxygen production at the DCM. Nor does a 15% increase in re-mineralization rate (assuming Q 10  = 2; 2°C warming) have significant effect on net sub-surface oxygen accumulation. However, changes in the relative production of particulate (POM) and dissolved organic material (DOM) generate relatively large changes in net sub-surface oxygen production. As POM/DOM production is a function of plankton community composition, this implies plankton biodiversity and food web structure may be important factors influencing O 2 production in a warmer ocean.This article is part of the themed issue 'Ocean ventilation and deoxygenation in a warming world'. © 2017 The Author(s).

  11. Evolutionary bursts in Euphorbia (Euphorbiaceae) are linked with photosynthetic pathway.

    Science.gov (United States)

    Horn, James W; Xi, Zhenxiang; Riina, Ricarda; Peirson, Jess A; Yang, Ya; Dorsey, Brian L; Berry, Paul E; Davis, Charles C; Wurdack, Kenneth J

    2014-12-01

    The mid-Cenozoic decline of atmospheric CO2 levels that promoted global climate change was critical to shaping contemporary arid ecosystems. Within angiosperms, two CO2 -concentrating mechanisms (CCMs)-crassulacean acid metabolism (CAM) and C4 -evolved from the C3 photosynthetic pathway, enabling more efficient whole-plant function in such environments. Many angiosperm clades with CCMs are thought to have diversified rapidly due to Miocene aridification, but links between this climate change, CCM evolution, and increased net diversification rates (r) remain to be further understood. Euphorbia (∼2000 species) includes a diversity of CAM-using stem succulents, plus a single species-rich C4 subclade. We used ancestral state reconstructions with a dated molecular phylogeny to reveal that CCMs independently evolved 17-22 times in Euphorbia, principally from the Miocene onwards. Analyses assessing among-lineage variation in r identified eight Euphorbia subclades with significantly increased r, six of which have a close temporal relationship with a lineage-corresponding CCM origin. Our trait-dependent diversification analysis indicated that r of Euphorbia CCM lineages is approximately threefold greater than C3 lineages. Overall, these results suggest that CCM evolution in Euphorbia was likely an adaptive strategy that enabled the occupation of increased arid niche space accompanying Miocene expansion of arid ecosystems. These opportunities evidently facilitated recent, replicated bursts of diversification in Euphorbia. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  12. Effects of ultraviolet radiation (UVA+UVB) on young gametophytes of Gelidium floridanum: growth rate, photosynthetic pigments, carotenoids, photosynthetic performance, and ultrastructure.

    Science.gov (United States)

    Simioni, Carmen; Schmidt, Eder C; Felix, Marthiellen R de L; Polo, Luz Karime; Rover, Ticiane; Kreusch, Marianne; Pereira, Debora T; Chow, Fungyi; Ramlov, Fernanda; Maraschin, Marcelo; Bouzon, Zenilda L

    2014-01-01

    This study investigated the effects of radiation (PAR+UVA+UVB) on the development and growth rates (GRs) of young gametophytes of Gelidium floridanum. In addition, photosynthetic pigments were quantified, carotenoids identified, and photosynthetic performance assessed. Over a period of 3 days, young gametophytes were cultivated under laboratory conditions and exposed to photosynthetically active radiation (PAR) at 80 μmol photons m(-2) s(-1) and PAR+UVA (0.70 W m(-2))+UVB (0.35 W m(-2)) for 3 h per day. The samples were processed for light and electron microscopy to analyze the ultrastructure features, as well as carry out metabolic studies of GRs, quantify the content of photosynthetic pigments, identify carotenoids and assess photosynthetic performance. PAR+UVA+UVB promoted increase in cell wall thickness, accumulation of floridean starch grains in the cytoplasm and disruption of chloroplast internal organization. Algae exposed to PAR+UVA+UVB also showed a reduction in GR of 97%. Photosynthetic pigments, in particular, phycoerythrin and allophycocyanin contents, decreased significantly from UV radiation exposure. This result agrees with the decrease in photosynthetic performance observed after exposure to ultraviolet radiation, as measured by a decrease in the electron transport rate (ETR), where values of ETRmax declined approximately 44.71%. It can be concluded that radiation is a factor that affects the young gametophytes of G. floridanum at this stage of development. © 2014 The American Society of Photobiology.

  13. Effects of ultraviolet radiation on photosynthetic performance and N2 fixation in Trichodesmium erythraeum IMS 101

    Science.gov (United States)

    Cai, Xiaoni; Hutchins, David A.; Fu, Feixue; Gao, Kunshan

    2017-10-01

    Biological effects of ultraviolet radiation (UVR; 280-400 nm) on marine primary producers are of general concern, as oceanic carbon fixers that contribute to the marine biological CO2 pump are being exposed to increasing UV irradiance due to global change and ozone depletion. We investigated the effects of UV-B (280-320 nm) and UV-A (320-400 nm) on the biogeochemically critical filamentous marine N2-fixing cyanobacterium Trichodesmium (strain IMS101) using a solar simulator as well as under natural solar radiation. Short exposure to UV-B, UV-A, or integrated total UVR significantly reduced the effective quantum yield of photosystem II (PSII) and photosynthetic carbon and N2 fixation rates. Cells acclimated to low light were more sensitive to UV exposure compared to high-light-grown ones, which had more UV-absorbing compounds, most likely mycosporine-like amino acids (MAAs). After acclimation under natural sunlight, the specific growth rate was lower (by up to 44 %), MAA content was higher, and average trichome length was shorter (by up to 22 %) in the full spectrum of solar radiation with UVR, than under a photosynthetically active radiation (PAR) alone treatment (400-700 nm). These results suggest that prior shipboard experiments in UV-opaque containers may have substantially overestimated in situ nitrogen fixation rates by Trichodesmium, and that natural and anthropogenic elevation of UV radiation intensity could significantly inhibit this vital source of new nitrogen to the current and future oligotrophic oceans.

  14. Conversion Efficiency of Photosynthetically Active Radiation Into Acacia mearnsii Biomass

    Directory of Open Access Journals (Sweden)

    Elder Eloy

    2018-02-01

    Full Text Available ABSTRACT The objective of this experiment was to determine the conversion efficiency of intercepted photosynthetically active radiation into biomass of Acacia mearnsii De Wild. seedlings. A forest species, plastic tubes (90 cm3, and 11 evaluation periods (up to 180 days after emergence were used in this study. The leaf area index (LAI, total dry biomass (BIO, global solar radiation (GSR, cumulative intercepted photosynthetically active radiation (PARic, and conversion efficiency of radiation (εb were determined using a pyranometer (LI200X, LICOR. The value of εb in BIO seedlings of Acacia mearnsii was 7.76 g MJ-1. LAI was directly related to the efficiency of PARic, and this influenced the development, production potential and accumulation of BIO. The value of GSR flow was 11.81 MJ m-2 day-1, while the value inside the greenhouse was 6.26 MJ m-2 day-1.

  15. Globalization

    DEFF Research Database (Denmark)

    Plum, Maja

    Globalization is often referred to as external to education - a state of affair facing the modern curriculum with numerous challenges. In this paper it is examined as internal to curriculum; analysed as a problematization in a Foucaultian sense. That is, as a complex of attentions, worries, ways...... of reasoning, producing curricular variables. The analysis is made through an example of early childhood curriculum in Danish Pre-school, and the way the curricular variable of the pre-school child comes into being through globalization as a problematization, carried forth by the comparative practices of PISA...

  16. Globalization

    OpenAIRE

    F. Gerard Adams

    2008-01-01

    The rapid globalization of the world economy is causing fundamental changes in patterns of trade and finance. Some economists have argued that globalization has arrived and that the world is “flat†. While the geographic scope of markets has increased, the author argues that new patterns of trade and finance are a result of the discrepancies between “old†countries and “new†. As the differences are gradually wiped out, particularly if knowledge and technology spread worldwide, the t...

  17. Photosynthetic carbon metabolism in the submerged aquatic angiosperm Scirpus subterminalis

    Energy Technology Data Exchange (ETDEWEB)

    Beer, S; Wetzel, R G

    1981-01-01

    Scirpus subterminalis Torr., a submerged angiosperm abundant in many hardwater lakes of the Great Lakes region, was investigated for various photosynthetic carbon fixation properties in relation to available inorganic carbon and levels of carbon fixing enzymes. Photosynthetic experiments were CO/sub 2/ and HCO/sub 3//sup -/ were supplied at various concentrations showed that Scirpus was able to utilize HCO/sub 3//sup -/ at those concentrations close to natural conditions. However, when CO/sub 2/ concentrations were increased above ambient, photosynthetic rates increased markedly. It was concluded that the photosynthetic potential of this plant in many natural situations may be limited by inorganic carbon uptake in the light. Phosphoenolpyruvate carboxylase (PEPcase)/ribulose-1,5-bisphosphate carboxylase (ruBPcase) ratios of the leaves varied between 0.5 and 0.9 depending on substrate concentration during assay. The significance of PEP-mediated carbon fixation of Scirpus (basically a C/sub 3/ plant) in the dark was investigated. Malate accumulated in the leaves during the dark period of a 24-h cycle and malate levels decreased significantly during the following light period. The accumulation was not due to transport of malate from the roots. Carbon uptake rates in the dark by the leaves of Scirpus were lower than malate accumulation rates. Therefore, part of the malate was likely derived from respired CO/sub 2/. Carbon uptake rates in the light were much higher than malate turnover rates. It was estimated that carbon fixation via malate could contribute up to 12% to net photosynthetic rates. The ecological significance of this type of metabolism in submerged aquatics is discussed.

  18. Photosynthetic light reactions at the gold interface

    NARCIS (Netherlands)

    Kamran, Muhammad

    2014-01-01

    In the project described in this thesis we studied a simple bio-electronic device for solar energy conversion by surface-assembly of photosynthetic pigment-protein complexes on a bare gold-electrode. Optical excitation of the photosynthetic pigments gives rise to charge separation in the so-called

  19. Global genomic analysis of intraductal papillary mucinous neoplasms of the pancreas reveals significant molecular differences compared to ductal adenocarcinoma.

    Science.gov (United States)

    Fritz, Stefan; Fernandez-del Castillo, Carlos; Mino-Kenudson, Mari; Crippa, Stefano; Deshpande, Vikram; Lauwers, Gregory Y; Warshaw, Andrew L; Thayer, Sarah P; Iafrate, A John

    2009-03-01

    To determine whether intraductal papillary mucinous neoplasms of the pancreas (IPMNs) have a different genetic background compared with ductal adenocarcinoma (PDAC). The biologic and clinical behavior of IPMNs and IPMN-associated adenocarcinomas is different from PDAC in having a less aggressive tumor growth and significantly improved survival. Up to date, the molecular mechanisms underlying the clinical behavior of IPMNs are incompletely understood. 128 cystic pancreatic lesions were prospectively identified during the course of 2 years. From the corresponding surgical specimens, 57 IPMNs were separated and subdivided by histologic criteria into those with low-grade dysplasia, moderate dysplasia, high-grade dysplasia, and invasive cancer. Twenty specimens were suitable for DNA isolation and subsequent performance of array CGH. While none of the IPMNs with low-grade dysplasia displayed detectable chromosomal aberrations, IPMNs with moderate and high-grade dysplasia showed frequent copy number alterations. Commonly lost regions were located on chromosome 5q, 6q, 10q, 11q, 13q, 18q, and 22q. The incidence of loss of chromosome 5q, 6q, and 11q was significantly higher in IPMNs with high-grade dysplasia or invasion compared with PDAC. Ten of 13 IPMNs with moderate dysplasia or malignancy had loss of part or all of chromosome 6q, with a minimal deleted region between linear positions 78.0 and 130.0. This study is the first to use array CGH to characterize IPMNs. Recurrent cytogenetic alterations were identified and were different than those described in PDAC. Array CGH may help distinguish between these 2 entities and give insight into the differences in their biology and prognosis.

  20. Effect of gamma radiation on photosynthetic metabolism of Chlorella pyrenoidosa studied by 14CO2 assimilation

    International Nuclear Information System (INIS)

    Martin Moreno, C.; Fernandez Gonzalez, J.

    1983-01-01

    The effect of five dose of gamma radiation (10, 100, 500, 1000 and 5000 Gy) on photosynthetic activity and metabolism of the primary products of photosynthesis has been studied, on Chlorella pyrenoidoBa cultures, by 14 C O 2 assimilation. The photosynthetic assimilation rate is remarkably depressed after irradiation at 500, 1000 and 5000 Gy dose, which also produce a significant change in radioactivity distribution pattern of primary compounds from photosynthesis. No significant effects have been observed on photosynthetic metabolism after irradiation at 10 and 100 Gy. (Author) 19 refs

  1. The role of forest trees and their mycorrhizal fungi in carbonate rock weathering and its significance for global carbon cycling.

    Science.gov (United States)

    Thorley, Rachel M S; Taylor, Lyla L; Banwart, Steve A; Leake, Jonathan R; Beerling, David J

    2015-09-01

    On million-year timescales, carbonate rock weathering exerts no net effect on atmospheric CO2 concentration. However, on timescales of decades-to-centuries, it can contribute to sequestration of anthropogenic CO2 and increase land-ocean alkalinity flux, counteracting ocean acidification. Historical evidence indicates this flux is sensitive to land use change, and recent experimental evidence suggests that trees and their associated soil microbial communities are major drivers of continental mineral weathering. Here, we review key physical and chemical mechanisms by which the symbiotic mycorrhizal fungi of forest tree roots potentially enhance carbonate rock weathering. Evidence from our ongoing field study at the UK's national pinetum confirms increased weathering of carbonate rocks by a wide range of gymnosperm and angiosperm tree species that form arbuscular (AM) or ectomycorrhizal (EM) fungal partnerships. We demonstrate that calcite-containing rock grains under EM tree species weather significantly faster than those under AM trees, an effect linked to greater soil acidification by EM trees. Weathering and corresponding alkalinity export are likely to increase with rising atmospheric CO2 and associated climate change. Our analyses suggest that strategic planting of fast-growing EM angiosperm taxa on calcite- and dolomite-rich terrain might accelerate the transient sink for atmospheric CO2 and slow rates of ocean acidification. © 2014 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.

  2. Photosynthetic rate, dry matter accumulation and yield inter-relationships jn genotypes of rice

    International Nuclear Information System (INIS)

    Devendra, R.; Udaya Kumar, M.; Krishna Sastry, K.S.

    1980-01-01

    The relationship between photosynthetic efficiency, dry matter accumulation and yield in five genotypes of paddy derived from a single cross between Jaya X Halubbalu was studied. Photosynthetic efficiency of younger leaves, on the main tiller was higher than in the older leaves. A significant positive correlation between RuDPcase activity and photosynthetic efficiency was observed in these genotypes. Also a similar positive correlation between dry matter production and photosynthetic efficiency during vegetative period but not during post-anthesis period was observed. Genotypes with high photosynthetic efficiency and also the genotypes with high LAD produced higher dry matter. A reduction in LAD or in photosynthetic efficiency during the post-anthesis period and thus a reduction in source capacity which occurred specially in late types resulted in a lesser ratio between productive and total tillers and also higher percent sterility. Differences in yield amongst the genotypes were not significant, since in the late types MR. 333 and MR. 335, the post-anthesis dry matter production was low due to lesser source capacity. But in the early types, though the total dry matter was less, the post-anthesis source capacity was high. The importance of post-anthesis leaf area of photo-synthetic efficiency in productivity in genotypes of rice is highlighted. (author)

  3. A remotely sensed pigment index reveals photosynthetic phenology in evergreen conifers.

    Science.gov (United States)

    Gamon, John A; Huemmrich, K Fred; Wong, Christopher Y S; Ensminger, Ingo; Garrity, Steven; Hollinger, David Y; Noormets, Asko; Peñuelas, Josep

    2016-11-15

    In evergreen conifers, where the foliage amount changes little with season, accurate detection of the underlying "photosynthetic phenology" from satellite remote sensing has been difficult, presenting challenges for global models of ecosystem carbon uptake. Here, we report a close correspondence between seasonally changing foliar pigment levels, expressed as chlorophyll/carotenoid ratios, and evergreen photosynthetic activity, leading to a "chlorophyll/carotenoid index" (CCI) that tracks evergreen photosynthesis at multiple spatial scales. When calculated from NASA's Moderate Resolution Imaging Spectroradiometer satellite sensor, the CCI closely follows the seasonal patterns of daily gross primary productivity of evergreen conifer stands measured by eddy covariance. This discovery provides a way of monitoring evergreen photosynthetic activity from optical remote sensing, and indicates an important regulatory role for carotenoid pigments in evergreen photosynthesis. Improved methods of monitoring photosynthesis from space can improve our understanding of the global carbon budget in a warming world of changing vegetation phenology.

  4. Quantum measurement corrections to CIDNP in photosynthetic reaction centers

    International Nuclear Information System (INIS)

    Kominis, Iannis K

    2013-01-01

    Chemically induced dynamic nuclear polarization is a signature of spin order appearing in many photosynthetic reaction centers. Such polarization, significantly enhanced above thermal equilibrium, is known to result from the nuclear spin sorting inherent in the radical pair mechanism underlying long-lived charge-separated states in photosynthetic reaction centers. We will show here that the recently understood fundamental quantum dynamics of radical-ion-pair reactions open up a new and completely unexpected pathway toward obtaining chemically induced dynamic nuclear polarization signals. The fundamental decoherence mechanism inherent in the recombination process of radical pairs is shown to produce nuclear spin polarizations of the order of 10 4 times (or more) higher than the thermal equilibrium value at the Earth's magnetic field relevant to natural photosynthesis. This opens up the possibility of a fundamentally new exploration of the biological significance of high nuclear polarizations in photosynthesis. (paper)

  5. Enhanced Practical Photosynthetic CO2 Mitigation. Quarterly Technical Report

    International Nuclear Information System (INIS)

    Gregory Kremer; David J. Bayless; Morgan Vis; Michael Prudich; Keith Cooksey; Jeff Muhs

    2005-01-01

    This report highlights significant achievements in the Enhanced Practical Photosynthetic CO 2 Mitigation Project during the ending 12/31/2004. Specific results and accomplishments for the program include review of pilot scale testing and design of a new bioreactor. Testing confirmed that algae can be grown in a sustainable fashion in the pilot bioreactor, even with intermittent availability of sunlight. The pilot-scale tests indicated that algal growth rate followed photon delivery during productivity testing

  6. Hybrid system of semiconductor and photosynthetic protein

    International Nuclear Information System (INIS)

    Kim, Younghye; Shin, Seon Ae; Lee, Jaehun; Yang, Ki Dong; Nam, Ki Tae

    2014-01-01

    Photosynthetic protein has the potential to be a new attractive material for solar energy absorption and conversion. The development of semiconductor/photosynthetic protein hybrids is an example of recent progress toward efficient, clean and nanostructured photoelectric systems. In the review, two biohybrid systems interacting through different communicating methods are addressed: (1) a photosynthetic protein immobilized semiconductor electrode operating via electron transfer and (2) a hybrid of semiconductor quantum dots and photosynthetic protein operating via energy transfer. The proper selection of materials and functional and structural modification of the components and optimal conjugation between them are the main issues discussed in the review. In conclusion, we propose the direction of future biohybrid systems for solar energy conversion systems, optical biosensors and photoelectric devices. (topical reviews)

  7. Separation, identification and quantification of photosynthetic ...

    African Journals Online (AJOL)

    Thirty one photosynthetic pigments (chlorophylls, carotenoids and degradation products) from the seaweeds, Codium dwarkense, (Chlorophyta), , Laurencia obtusa , (Rhodophyta) and , Lobophora variegata, (Phaeophyta), were separated in a single-step procedure by reversed phase high-performance liquid ...

  8. Effect of Pot Size on Various Characteristics Related to Photosynthetic Matter Production in Soybean Plants

    Directory of Open Access Journals (Sweden)

    Minobu Kasai

    2012-01-01

    Full Text Available Despite the wide uses of potted plants, information on how pot size affects plant photosynthetic matter production is still considerably limited. This study investigated with soybean plants how transplantation into larger pots affects various characteristics related to photosynthetic matter production. The transplantation was analyzed to increase leaf photosynthetic rate, transpiration rate, and stomatal conductance without affecting significantly leaf intercellular CO2 concentration, implicating that the transplantation induced equal increases in the rate of CO2 diffusion via leaf stomata and the rate of CO2 fixation in leaf photosynthetic cells. Analyses of Rubisco activity and contents of a substrate (ribulose-1,5-bisphosphate (RuBP for Rubisco and total protein in leaf suggested that an increase in leaf Rubisco activity, which is likely to result from an increase in leaf Rubisco content, could contribute to the transplantation-induced increase in leaf photosynthetic rate. Analyses of leaf major photosynthetic carbohydrates and dry weights of source and sink organs revealed that transplantation increased plant sink capacity that uses leaf starch, inducing a decrease in leaf starch content and an increase in whole plant growth, particularly, growth of sink organs. Previously, in the same soybean species, it was demonstrated that negative correlation exists between leaf starch content and photosynthetic rate and that accumulation of starch in leaf decreases the rate of CO2 diffusion within leaf. Thus, it was suggested that the transplantation-induced increase in plant sink capacity decreasing leaf starch content could cause the transplantation-induced increase in leaf photosynthetic rate by inducing an increase in the rate of CO2 diffusion within leaf and thereby substantiating an increase in leaf Rubisco activity in vivo. It was therefore concluded that transplantation of soybean plants into larger pots attempted in this study increased the

  9. Still acting green: continued expression of photosynthetic genes in the heterotrophic Dinoflagellate Pfiesteria piscicida (Peridiniales, Alveolata.

    Directory of Open Access Journals (Sweden)

    Gwang Hoon Kim

    Full Text Available The loss of photosynthetic function should lead to the cessation of expression and finally loss of photosynthetic genes in the new heterotroph. Dinoflagellates are known to have lost their photosynthetic ability several times. Dinoflagellates have also acquired photosynthesis from other organisms, either on a long-term basis or as "kleptoplastids" multiple times. The fate of photosynthetic gene expression in heterotrophs can be informative into evolution of gene expression patterns after functional loss, and the dinoflagellates ability to acquire new photosynthetic function through additional endosymbiosis. To explore this we analyzed a large-scale EST database consisting of 151,091 unique sequences (29,170 contigs, 120,921 singletons obtained from 454 pyrosequencing of the heterotrophic dinoflagellate Pfiesteria piscicida. About 597 contigs from P. piscicida showed significant homology (E-value photosynthetic function. Most of the genes involved in the Calvin-Benson cycle were found, genes of the light-dependent reaction were also identified. Also genes of associated pathways including the chorismate pathway and genes involved in starch metabolism were discovered. BLAST searches and phylogenetic analysis suggest that these plastid-associated genes originated from several different photosynthetic ancestors. The Calvin-Benson cycle genes are mostly associated with genes derived from the secondary plastids of peridinin-containing dinoflagellates, while the light-harvesting genes are derived from diatoms, or diatoms that are tertiary plastids in other dinoflagellates. The continued expression of many genes involved in photosynthetic pathways indicates that the loss of transcriptional regulation may occur well after plastid loss and could explain the organism's ability to "capture" new plastids (i.e. different secondary endosymbiosis or tertiary symbioses to renew photosynthetic function.

  10. Still acting green: continued expression of photosynthetic genes in the heterotrophic Dinoflagellate Pfiesteria piscicida (Peridiniales, Alveolata).

    Science.gov (United States)

    Kim, Gwang Hoon; Jeong, Hae Jin; Yoo, Yeong Du; Kim, Sunju; Han, Ji Hee; Han, Jong Won; Zuccarello, Giuseppe C

    2013-01-01

    The loss of photosynthetic function should lead to the cessation of expression and finally loss of photosynthetic genes in the new heterotroph. Dinoflagellates are known to have lost their photosynthetic ability several times. Dinoflagellates have also acquired photosynthesis from other organisms, either on a long-term basis or as "kleptoplastids" multiple times. The fate of photosynthetic gene expression in heterotrophs can be informative into evolution of gene expression patterns after functional loss, and the dinoflagellates ability to acquire new photosynthetic function through additional endosymbiosis. To explore this we analyzed a large-scale EST database consisting of 151,091 unique sequences (29,170 contigs, 120,921 singletons) obtained from 454 pyrosequencing of the heterotrophic dinoflagellate Pfiesteria piscicida. About 597 contigs from P. piscicida showed significant homology (E-value photosynthetic function. Most of the genes involved in the Calvin-Benson cycle were found, genes of the light-dependent reaction were also identified. Also genes of associated pathways including the chorismate pathway and genes involved in starch metabolism were discovered. BLAST searches and phylogenetic analysis suggest that these plastid-associated genes originated from several different photosynthetic ancestors. The Calvin-Benson cycle genes are mostly associated with genes derived from the secondary plastids of peridinin-containing dinoflagellates, while the light-harvesting genes are derived from diatoms, or diatoms that are tertiary plastids in other dinoflagellates. The continued expression of many genes involved in photosynthetic pathways indicates that the loss of transcriptional regulation may occur well after plastid loss and could explain the organism's ability to "capture" new plastids (i.e. different secondary endosymbiosis or tertiary symbioses) to renew photosynthetic function.

  11. Oxygen Concentration Inside a Functioning Photosynthetic Cell

    OpenAIRE

    Kihara, Shigeharu; Hartzler, Daniel A.; Savikhin, Sergei

    2014-01-01

    The excess oxygen concentration in the photosynthetic membranes of functioning oxygenic photosynthetic cells was estimated using classical diffusion theory combined with experimental data on oxygen production rates of cyanobacterial cells. The excess oxygen concentration within the plesiomorphic cyanobacterium Gloeobactor violaceus is only 0.025 μM, or four orders of magnitude lower than the oxygen concentration in air-saturated water. Such a low concentration suggests that the first oxygenic...

  12. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Gregory Kremer; Dr. David J. Bayless; Dr. Morgan Vis; Dr. Michael Prudich; Dr. Keith Cooksey; Dr. Jeff Muhs

    2001-07-25

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 4/03/2001 through 7/02/2001. Most of the achievements are milestones in our efforts to complete the tasks and subtasks that constitute the project objectives. Note that this version of the quarterly technical report is a revision to add the reports from subcontractors Montana State and Oak Ridge National Laboratories The significant accomplishments for this quarter include: Development of an experimental plan and initiation of experiments to create a calibration curve that correlates algal chlorophyll levels with carbon levels (to simplify future experimental procedures); Completion of debugging of the slug flow reactor system, and development of a plan for testing the pressure drop of the slug flow reactor; Design and development of a new bioreactor screen design which integrates the nutrient delivery drip system and the harvesting system; Development of an experimental setup for testing the new integrated drip system/harvesting system; Completion of model-scale bioreactor tests examining the effects of CO{sub 2} concentration levels and lighting levels on Nostoc 86-3 growth rates; Completion of the construction of a larger model-scale bioreactor to improve and expand testing capabilities and initiation of tests; Substantial progress on construction of a pilot-scale bioreactor; and Preliminary economic analysis of photobioreactor deployment. Plans for next quarter's work are included in the conclusions. A preliminary economic analysis is included as an appendix.

  13. Changes of Photosynthetic Behaviors in Kappaphycus alvarezii Infected by Epiphyte.

    Science.gov (United States)

    Pang, Tong; Liu, Jianguo; Liu, Qian; Lin, Wei

    2011-01-01

    Epiphytic filamentous algae (EFA) were noted as a serious problem to reduce the production and quality of K. alvarezii. The morphological studies revealed that the main epiphyte on K. alvarezii was Neosiphonia savatieri in China. Though the harmful effects of EFA on the production of K. alvarezii have been reported, the detailed mechanism of the N. savatieri in limiting the production of K. alvarezii has not been studied yet. The present paper studied the effects of N. savatieri infection on photosynthetic behaviors in K. alvarezii by detecting chlorophyll fluorescence transient in vivo. The results revealed that damage of oxygen-evolving complex (OEC), decrease of active reaction centers (RCs), and the plastoquinone (PQ) pool as well as significant reduction in the performance indexes (PI) of PSII were caused by the infection of N. savatieri. The influence of N. savatieri on photosynthetic activity of K. alvarezii should be one of the important reasons to reduce the production of K. alvarezii infected by N. savatieri.

  14. Photosynthetic carbon reduction by seagrasses exposed to ultraviolet A radiation

    Science.gov (United States)

    1979-01-01

    The seagrasses Halophila engelmannii, Halodule wrightii, and Syringodium filiforme were examined for their intrinsic sensitivity to ultraviolet-A-UV-A and ultraviolet-B-UV-B radiation. The effect of UV-A on photosynthetically active radiation (PAR) was also determined. Ultraviolet-A and ultraviolet-B were studied with emphasis on the greater respective environmental consequence in terms of seagrass distribution and abundance. Results indicate that an intrinsic sensitivity to UV-A alone is apparent only in Halophila, while net photosynthesis in Halodule and Syringodium seems unaffected by the level of UV-A provided. The sensitivity of Halophila to UV-A in the absense of (PAR) indicates that the photosynthetic reaction does not need to be in operation for damage to occur. Other significant results are reported.

  15. Photosynthetic efficiency of Pedunculate oak seedlings under simulated water stress

    Directory of Open Access Journals (Sweden)

    Popović Zorica

    2010-01-01

    Full Text Available Photosynthetic performance of seedlings of Quercus robur exposed to short-term water stress in the laboratory conditions was assessed through the method of induced fluorometry. The substrate for seedlings was clayey loam, with the dominant texture fraction made of silt, followed by clay and fine sand, with total porosity 68.2%. Seedlings were separated in two groups: control (C (soil water regime in pots was maintained at the level of field water capacity and treated (water-stressed, WS (soil water regime was maintained in the range of wilting point and lentocapillary capacity. The photosynthetic efficiency was 0.642±0.25 and 0.522±0.024 (WS and C, respectively, which was mostly due to transplantation disturbances and sporadic leaf chlorosis. During the experiment Fv/Fm decreased in both groups (0.551±0.0100 and 0.427±0.018 in C and WS, respectively. Our results showed significant differences between stressed and control group, in regard to both observed parameters (Fv/Fm and T½. Photosynthetic efficiency of pedunculate oak seedlings was significantly affected by short-term water stress, but to a lesser extent than by sufficient watering.

  16. [Correlation research of photosynthetic characteristics and medicinal materials production with 4 Uncariae Cum Uncis].

    Science.gov (United States)

    Luo, Min; Song, Zhi-Qin; Yang, Ping-Fei; Liu, Hai; Yang, Zai-Gang; Wu, Ming-Kai

    2017-01-01

    Using four Uncariae Cum Uncis materials including Uncaria sinensis (HGT), U. hirsutea (MGT), Jianhe U. rhynchophylla (JHGT) and U. rhynchophylla(GT) as the research objects, the correlations between medicinal materials' yield and photosynthetic ecophysiology-factors in the plant exuberant growth period were studied. Results showed that the Uncaria plants net photosynthetic rate (Pn) changed by unimodal curve. There was not "midday depression" phenomenon. There was a different relationship among the photosynthetic ecophysiology-factors and between photosynthetic ecophysiology-factors and medicinal materials' yield. Pn,Tl,Gs had a significant correlation with medicinal materials' yield(M)and were the most important factors of growth. Copyright© by the Chinese Pharmaceutical Association.

  17. Oxygen concentration inside a functioning photosynthetic cell.

    Science.gov (United States)

    Kihara, Shigeharu; Hartzler, Daniel A; Savikhin, Sergei

    2014-05-06

    The excess oxygen concentration in the photosynthetic membranes of functioning oxygenic photosynthetic cells was estimated using classical diffusion theory combined with experimental data on oxygen production rates of cyanobacterial cells. The excess oxygen concentration within the plesiomorphic cyanobacterium Gloeobactor violaceus is only 0.025 μM, or four orders of magnitude lower than the oxygen concentration in air-saturated water. Such a low concentration suggests that the first oxygenic photosynthetic bacteria in solitary form could have evolved ∼2.8 billion years ago without special mechanisms to protect them against reactive oxygen species. These mechanisms instead could have been developed during the following ∼500 million years while the oxygen level in the Earth's atmosphere was slowly rising. Excess oxygen concentrations within individual cells of the apomorphic cyanobacteria Synechocystis and Synechococcus are 0.064 and 0.25 μM, respectively. These numbers suggest that intramembrane and intracellular proteins in isolated oxygenic photosynthetic cells are not subjected to excessively high oxygen levels. The situation is different for closely packed colonies of photosynthetic cells. Calculations show that the excess concentration within colonies that are ∼40 μm or larger in diameter can be comparable to the oxygen concentration in air-saturated water, suggesting that species forming colonies require protection against reactive oxygen species even in the absence of oxygen in the surrounding atmosphere. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  18. [Effects of low-light stress on photosynthetic characteristics of Paris polyphylla var. chinensis in artificial domestication cultivation].

    Science.gov (United States)

    Zheng, Shun-lin; Tian, Meng-liang; Liu, Jin-liang; Zhao, Ting-ting; Zhang, Zhong

    2014-09-01

    To decide on the optimum artificial domestication cultivation light environment for Paris polyphylla var. chinensis through investigating the effect of light intensity on leaf's gas exchange parameters, photosynthetic parameters, light saturation point and compensation point of Paris polyphylla var. chinensis. Different low-light stress gradients' effect on the growth of Paris polyphylla var. chinensis was compared with no low-light stress treatment through calculating leaf's gas exchange parameters, photosynthetic parameters, light saturation point and compensation point, and then all these parameters were statistically analyzed. Light intensity had significant influence on the photosynthetic characteristics of Paris polyphylla var. chinensis. With the strengthening of the low-light stress, chlorophyll content, gas exchange parameters, photosynthetic parameters P., AQY and light saturation point all gradually increased at first, and then decreased. However, both photosynthetic parameters Rd and light compensation point firstly decreased and then rose again. These results showed that too strong or too weak light intensity affected the optimization of photosynthetic parameters of Paris polyphylla var. chinensis. The optimal illuminance for each parameter was not completely same, but they could all reach a relative ideal state when the shading ranges between 40% and 60%. However, photosynthetic parameters deteriorated rapidly when the shading surpass 80%. For artificially cultivating Paris polyphylla var. chinensis in Baoxing,Sichuan or the similar ecological region, shading 40%-60% is the optimal light environment, which can enhance the photosynthesis of Paris polyphylla var. chinensis and promote the accumulation of photosynthetic products.

  19. Effects of ultraviolet radiation on photosynthetic performance and N2 fixation in Trichodesmium erythraeum IMS 101

    Directory of Open Access Journals (Sweden)

    X. Cai

    2017-10-01

    Full Text Available Biological effects of ultraviolet radiation (UVR; 280–400 nm on marine primary producers are of general concern, as oceanic carbon fixers that contribute to the marine biological CO2 pump are being exposed to increasing UV irradiance due to global change and ozone depletion. We investigated the effects of UV-B (280–320 nm and UV-A (320–400 nm on the biogeochemically critical filamentous marine N2-fixing cyanobacterium Trichodesmium (strain IMS101 using a solar simulator as well as under natural solar radiation. Short exposure to UV-B, UV-A, or integrated total UVR significantly reduced the effective quantum yield of photosystem II (PSII and photosynthetic carbon and N2 fixation rates. Cells acclimated to low light were more sensitive to UV exposure compared to high-light-grown ones, which had more UV-absorbing compounds, most likely mycosporine-like amino acids (MAAs. After acclimation under natural sunlight, the specific growth rate was lower (by up to 44 %, MAA content was higher, and average trichome length was shorter (by up to 22 % in the full spectrum of solar radiation with UVR, than under a photosynthetically active radiation (PAR alone treatment (400–700 nm. These results suggest that prior shipboard experiments in UV-opaque containers may have substantially overestimated in situ nitrogen fixation rates by Trichodesmium, and that natural and anthropogenic elevation of UV radiation intensity could significantly inhibit this vital source of new nitrogen to the current and future oligotrophic oceans.

  20. Nitrogen deposition's role in determining forest photosynthetic capacity; a FLUXNET synthesis

    Science.gov (United States)

    Fleischer, K.; Rebel, K.; van der Molen, M.; Erisman, J.; Wassen, M.; Dolman, H.

    2011-12-01

    There is growing evidence that nitrogen (N) deposition stimulates forest growth, as many forest ecosystems are N-limited. However, the significance of N deposition in determining the strength of the present and future terrestrial carbon sink is strongly debated. We investigated and quantified the effect of N deposition on ecosystem photosynthetic capacity (Amax) with the FLUXNET database, including 80 forest sites, covering the major forest types and climates of the world. The relative effect of climate and N deposition on photosynthesis was assessed with regression models. We found a significant positive correlation of Amax and N deposition for evergreen needleleaf forests in our dataset. We further found indications that foliar N and LAI scale positively with N deposition, reflecting the 2 mechanisms at which N is believed to cause an increase in carbon gain. We can support the hypothesis that foliar N is the principal scaling factor for canopy Amax across all forest types. Deciduous forests are less diverse in terms of climate and nutritional conditions for the included sites and these forests exhibited weak to no correlations with the included climate and N predictor variables. Quantifying the effect of N deposition on photosynthetic rates at the canopy level is an essential step for quantifying its contribution to the terrestrial carbon sink and for predicting vegetation response to N fertilization and global change in the future. The approach shows that eddy-covariance measurements of carbon fluxes at the canopy scale allow us to test hypotheses with respect to the expected nitrogen-photosynthesis relationships at the canopy scale.

  1. Melatonin Improves the Photosynthetic Carbon Assimilation and Antioxidant Capacity in Wheat Exposed to Nano-ZnO Stress

    Directory of Open Access Journals (Sweden)

    Zhiyu Zuo

    2017-10-01

    Full Text Available The release of nanoparticles into the environment is inevitable, which has raised global environmental concern. Melatonin is involved in various stress responses in plants. The present study investigated the effects of melatonin on photosynthetic carbon (C assimilation and plant growth in nano-ZnO stressed plants. It was found that melatonin improved the photosynthetic C assimilation in nano-ZnO stressed wheat plants, mainly due to the enhanced photosynthetic energy transport efficiency, higher chlorophyll concentration and higher activities of Rubisco and ATPases. In addition, melatonin enhanced the activities of antioxidant enzymes to protect the photosynthetic electron transport system in wheat leaves against the oxidative burst caused by nano-ZnO stress. These results suggest that melatonin could improve the tolerance of wheat plants to nano-ZnO stress.

  2. The In Vitro Mass-Produced Model Mycorrhizal Fungus, Rhizophagus irregularis, Significantly Increases Yields of the Globally Important Food Security Crop Cassava

    Science.gov (United States)

    Ceballos, Isabel; Ruiz, Michael; Fernández, Cristhian; Peña, Ricardo

    2013-01-01

    The arbuscular mycorrhizal symbiosis is formed between arbuscular mycorrhizal fungi (AMF) and plant roots. The fungi provide the plant with inorganic phosphate (P). The symbiosis can result in increased plant growth. Although most global food crops naturally form this symbiosis, very few studies have shown that their practical application can lead to large-scale increases in food production. Application of AMF to crops in the tropics is potentially effective for improving yields. However, a main problem of using AMF on a large-scale is producing cheap inoculum in a clean sterile carrier and sufficiently concentrated to cheaply transport. Recently, mass-produced in vitro inoculum of the model mycorrhizal fungus Rhizophagus irregularis became available, potentially making its use viable in tropical agriculture. One of the most globally important food plants in the tropics is cassava. We evaluated the effect of in vitro mass-produced R. irregularis inoculum on the yield of cassava crops at two locations in Colombia. A significant effect of R. irregularis inoculation on yield occurred at both sites. At one site, yield increases were observed irrespective of P fertilization. At the other site, inoculation with AMF and 50% of the normally applied P gave the highest yield. Despite that AMF inoculation resulted in greater food production, economic analyses revealed that AMF inoculation did not give greater return on investment than with conventional cultivation. However, the amount of AMF inoculum used was double the recommended dose and was calculated with European, not Colombian, inoculum prices. R. irregularis can also be manipulated genetically in vitro, leading to improved plant growth. We conclude that application of in vitro R. irregularis is currently a way of increasing cassava yields, that there is a strong potential for it to be economically profitable and that there is enormous potential to improve this efficiency further in the future. PMID:23950975

  3. The in vitro mass-produced model mycorrhizal fungus, Rhizophagus irregularis, significantly increases yields of the globally important food security crop cassava.

    Directory of Open Access Journals (Sweden)

    Isabel Ceballos

    Full Text Available The arbuscular mycorrhizal symbiosis is formed between arbuscular mycorrhizal fungi (AMF and plant roots. The fungi provide the plant with inorganic phosphate (P. The symbiosis can result in increased plant growth. Although most global food crops naturally form this symbiosis, very few studies have shown that their practical application can lead to large-scale increases in food production. Application of AMF to crops in the tropics is potentially effective for improving yields. However, a main problem of using AMF on a large-scale is producing cheap inoculum in a clean sterile carrier and sufficiently concentrated to cheaply transport. Recently, mass-produced in vitro inoculum of the model mycorrhizal fungus Rhizophagus irregularis became available, potentially making its use viable in tropical agriculture. One of the most globally important food plants in the tropics is cassava. We evaluated the effect of in vitro mass-produced R. irregularis inoculum on the yield of cassava crops at two locations in Colombia. A significant effect of R. irregularis inoculation on yield occurred at both sites. At one site, yield increases were observed irrespective of P fertilization. At the other site, inoculation with AMF and 50% of the normally applied P gave the highest yield. Despite that AMF inoculation resulted in greater food production, economic analyses revealed that AMF inoculation did not give greater return on investment than with conventional cultivation. However, the amount of AMF inoculum used was double the recommended dose and was calculated with European, not Colombian, inoculum prices. R. irregularis can also be manipulated genetically in vitro, leading to improved plant growth. We conclude that application of in vitro R. irregularis is currently a way of increasing cassava yields, that there is a strong potential for it to be economically profitable and that there is enormous potential to improve this efficiency further in the future.

  4. High density, genome-wide markers and intra-specific replication yield an unprecedented phylogenetic reconstruction of a globally significant, speciose lineage of Eucalyptus.

    Science.gov (United States)

    Jones, Rebecca C; Nicolle, Dean; Steane, Dorothy A; Vaillancourt, René E; Potts, Brad M

    2016-12-01

    We used genome-wide markers and an unprecedented scale of sampling to construct a phylogeny for a globally significant Eucalyptus lineage that has been impacted by hybridisation, recent radiation and morphological convergence. Our approach, using 3109 DArT markers distributed throughout the genome and 540 samples covering 185 terminal taxa in sections Maidenaria, Exsertaria, Latoangulatae and related smaller sections, with multiple geographically widespread samples per terminal taxon, produced a phylogeny that largely matched the morphological treatment of sections, though sections Exsertaria and Latoangulatae were polyphyletic. At lower levels there were numerous inconsistencies between the morphological treatment and the molecular phylogeny, and taxa within the three main sections were generally not monophyletic at the series (at least 62% polyphyly) or species (at least 52% polyphyly) level. Some of the discrepancies appear to be the result of morphological convergence or misclassifications, and we propose some taxonomic reassessments to address this. However, many inconsistencies appear to be the products of incomplete speciation and/or hybridisation. Our analysis represents a significant advance on previous phylogenies of these important eucalypt sections (which have mainly used single samples to represent each species), thus providing a robust phylogenetic framework for evolutionary and ecological studies. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Chlorophyll Fluorescence Imaging Uncovers Photosynthetic Fingerprint of Citrus Huanglongbing

    Directory of Open Access Journals (Sweden)

    Haiyan Cen

    2017-08-01

    Full Text Available Huanglongbing (HLB is one of the most destructive diseases of citrus, which has posed a serious threat to the global citrus production. This research was aimed to explore the use of chlorophyll fluorescence imaging combined with feature selection to characterize and detect the HLB disease. Chlorophyll fluorescence images of citrus leaf samples were measured by an in-house chlorophyll fluorescence imaging system. The commonly used chlorophyll fluorescence parameters provided the first screening of HLB disease. To further explore the photosynthetic fingerprint of HLB infected leaves, three feature selection methods combined with the supervised classifiers were employed to identify the unique fluorescence signature of HLB and perform the three-class classification (i.e., healthy, HLB infected, and nutrient deficient leaves. Unlike the commonly used fluorescence parameters, this novel data-driven approach by using the combination of the mean fluorescence parameters and image features gave the best classification performance with the accuracy of 97%, and presented a better interpretation for the spatial heterogeneity of photochemical and non-photochemical components in HLB infected citrus leaves. These results imply the potential of the proposed approach for the citrus HLB disease diagnosis, and also provide a valuable insight for the photosynthetic response to the HLB disease.

  6. Carotenoid Photoprotection in Artificial Photosynthetic Antennas

    Energy Technology Data Exchange (ETDEWEB)

    Kloz, Miroslav [VU Univ., Amsterdam (Netherlands); Pillai, Smitha [Arizona State Univ., Tempe, AZ (United States); Kodis, Gerdenis [Arizona State Univ., Tempe, AZ (United States); Gust, Devens [Arizona State Univ., Tempe, AZ (United States); Moore, Thomas A. [Arizona State Univ., Tempe, AZ (United States); Moore, Ana L. [Arizona State Univ., Tempe, AZ (United States); van Grondelle, Rienk [VU Univ., Amsterdam (Netherlands); Kennis, John T. M. [VU Univ., Amsterdam (Netherlands)

    2011-04-14

    A series of phthalocyanine-carotenoid dyads in which a phenylamino group links a phthalocyanine to carotenoids having 8-11 backbone double bonds were examined by visible and near-infrared femtosecond pump-probe spectroscopy combined with global fitting analysis. The series of molecules has permitted investigation of the role of carotenoids in the quenching of excited states of cyclic tetrapyrroles. The transient behavior varied dramatically with the length of the carotenoid and the solvent environment. Clear spectroscopic signatures of radical species revealed photoinduced electron transfer as the main quenching mechanism for all dyads dissolved in a polar solvent (THF), and the quenching rate was almost independent of carotenoid length. However, in a nonpolar solvent (toluene), quenching rates displayed a strong dependence on the conjugation length of the carotenoid and the mechanism did not include charge separation. The lack of any rise time components of a carotenoid S1 signature in all experiments in toluene suggests that an excitonic coupling between the carotenoid S1 state and phthalocyanine Q state, rather than a conventional energy transfer process, is the major mechanism of quenching. A pronounced inhomogeneity of the system was observed and attributed to the presence of a phenyl-amino linker between phthalocyanine and carotenoids. On the basis of accumulated work on various caroteno-phthalocyanine dyads and triads, we have now identified three mechanisms of tetrapyrrole singlet excited state quenching by carotenoids in artificial systems: (i) Car-Pc electron transfer and recombination; (ii)1Pc to Car S1 energy transfer and fast internal conversion to the Car ground state; (iii) excitonic coupling between 1Pc and Car S1 and ensuing internal conversion to the ground state of the carotenoid. The dominant mechanism depends upon the exact molecular architecture and solvent environment

  7. Ultrafast fluorescence of photosynthetic crystals and light-harvesting complexes

    NARCIS (Netherlands)

    Oort, van B.F.

    2008-01-01

    This thesis focuses on the study of photosynthetic pigment protein complexes using time resolved fluorescence techniques. Fluorescence spectroscopy often requires attaching fluorescent labels to the proteins under investigation. With photosynthetic proteins this is not necessary, because these

  8. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    Energy Technology Data Exchange (ETDEWEB)

    Dr. David J. Bayless; Dr. Morgan Vis; Dr. Gregory Kremer; Dr. Michael Prudich; Dr. Keith Cooksey; Dr. Jeff Muhs

    2001-04-16

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 1/03/2001 through 4/02/2001. Many of the activities and accomplishments are continuations of work initiated and reported in last quarter's status report. Major activities and accomplishments for this quarter include: Three sites in Yellowstone National Park have been identified that may contain suitable organisms for use in a bioreactor; Full-scale culturing of one thermophilic organism from Yellowstone has progressed to the point that there is a sufficient quantity to test this organism in the model-scale bioreactor; The effects of the additive monoethanolamine on the growth of one thermophilic organism from Yellowstone has been tested; Testing of growth surface adhesion and properties is continuing; Construction of a larger model-scale bioreactor to improve and expand testing capabilities is completed and the facility is undergoing proof tests; Model-scale bioreactor tests examining the effects of CO{sub 2} concentration levels and lighting levels on organism growth rates are continuing; Alternative fiber optic based deep-penetration light delivery systems for use in the pilot-scale bioreactor have been designed, constructed and tested; An existing slug flow reactor system has been modified for use in this project, and a proof-of-concept test plan has been developed for the slug flow reactor; Research and testing of water-jet harvesting techniques is continuing, and a harvesting system has been designed for use in the model-scale bioreactor; and The investigation of comparative digital image analysis as a means for determining the ''density'' of algae on a growth surface is continuing Plans for next quarter's work and an update on the project's web page are included in the conclusions.

  9. Difference in photosynthetic performance among three peach ...

    African Journals Online (AJOL)

    The effects of low photosynthetic photon flux density (PPFD) on greenhouse grown peach trees ('Qingfeng': Prunus persica L. Batsch, 'NJN76': Prunus persica L. Batsch and 'Maixiang': P. persica var. nectarine) were investigated. Difference in photosynthesis rate (Pn) and stoma morphology among cultivars were studied.

  10. Photosynthetic carbon metabolism in freshwater phytoplankton

    International Nuclear Information System (INIS)

    Groeger, A.W.

    1986-01-01

    Photosynthetic carbon metabolism of natural assemblages of freshwater phytoplankton was measured by following the flow of inorganic 14 C into the photosynthetic end products polysaccharide protein, lipid, and soluble metabolites. Data were collected from a wide range of physical, chemical, and trophic conditions in six southern United States reservoirs, with the primary environmental variables of interest being light intensity and nutrient supply. Polysaccharide and protein were consistently the primary products of photosynthetic carbon metabolism, comprising an average of 70% of the total carbon fixation over a wide range of light intensities. Polysaccharide was quantitatively more important at higher light intensities, and protein at lower light intensities, as light intensity varied both with depth within the water column and over diurnal cycles. Polysaccharide synthesis was more variable over the diurnal period than was protein synthesis. Phytoplankton in the downlake epilimnion of Normandy Lake, a central Tennessee reservoir, responded to summer nitrogen (N) deficiency by increasing relative rates of lipid synthesis from 10-15% to 20-25% of the total photosynthetic carbon fixation. Phytoplankton in more nitrogen-sufficient areas of the reservoir maintained lower rates of lipid synthesis throughout the summer. These results document the occurrence in nature of a relationship between N-deficiency and increased lipid synthesis previously observed only in laboratory algal culture studies

  11. Natural strategies for photosynthetic light harvesting

    NARCIS (Netherlands)

    Croce, R.; van Amerongen, H.

    2014-01-01

    Photosynthetic organisms are crucial for life on Earth as they provide food and oxygen and are at the basis of most energy resources. They have a large variety of light-harvesting strategies that allow them to live nearly everywhere where sunlight can penetrate. They have adapted their pigmentation

  12. Excitons in intact cells of photosynthetic bacteria.

    Science.gov (United States)

    Freiberg, Arvi; Pajusalu, Mihkel; Rätsep, Margus

    2013-09-26

    Live cells and regular crystals seem fundamentally incompatible. Still, effects characteristic to ideal crystals, such as coherent sharing of excitation, have been recently used in many studies to explain the behavior of several photosynthetic complexes, especially the inner workings of the light-harvesting apparatus of the oldest known photosynthetic organisms, the purple bacteria. To this date, there has been no concrete evidence that the same effects are instrumental in real living cells, leaving a possibility that this is an artifact of unnatural study conditions, not a real effect relevant to the biological operation of bacteria. Hereby, we demonstrate survival of collective coherent excitations (excitons) in intact cells of photosynthetic purple bacteria. This is done by using excitation anisotropy spectroscopy for tracking the temperature-dependent evolution of exciton bands in light-harvesting systems of increasing structural complexity. The temperature was gradually raised from 4.5 K to ambient temperature, and the complexity of the systems ranged from detergent-isolated complexes to complete bacterial cells. The results provide conclusive evidence that excitons are indeed one of the key elements contributing to the energetic and dynamic properties of photosynthetic organisms.

  13. Genome of the Asian longhorned beetle (Anoplophora glabripennis), a globally significant invasive species, reveals key functional and evolutionary innovations at the beetle-plant interface.

    Science.gov (United States)

    McKenna, Duane D; Scully, Erin D; Pauchet, Yannick; Hoover, Kelli; Kirsch, Roy; Geib, Scott M; Mitchell, Robert F; Waterhouse, Robert M; Ahn, Seung-Joon; Arsala, Deanna; Benoit, Joshua B; Blackmon, Heath; Bledsoe, Tiffany; Bowsher, Julia H; Busch, André; Calla, Bernarda; Chao, Hsu; Childers, Anna K; Childers, Christopher; Clarke, Dave J; Cohen, Lorna; Demuth, Jeffery P; Dinh, Huyen; Doddapaneni, HarshaVardhan; Dolan, Amanda; Duan, Jian J; Dugan, Shannon; Friedrich, Markus; Glastad, Karl M; Goodisman, Michael A D; Haddad, Stephanie; Han, Yi; Hughes, Daniel S T; Ioannidis, Panagiotis; Johnston, J Spencer; Jones, Jeffery W; Kuhn, Leslie A; Lance, David R; Lee, Chien-Yueh; Lee, Sandra L; Lin, Han; Lynch, Jeremy A; Moczek, Armin P; Murali, Shwetha C; Muzny, Donna M; Nelson, David R; Palli, Subba R; Panfilio, Kristen A; Pers, Dan; Poelchau, Monica F; Quan, Honghu; Qu, Jiaxin; Ray, Ann M; Rinehart, Joseph P; Robertson, Hugh M; Roehrdanz, Richard; Rosendale, Andrew J; Shin, Seunggwan; Silva, Christian; Torson, Alex S; Jentzsch, Iris M Vargas; Werren, John H; Worley, Kim C; Yocum, George; Zdobnov, Evgeny M; Gibbs, Richard A; Richards, Stephen

    2016-11-11

    Relatively little is known about the genomic basis and evolution of wood-feeding in beetles. We undertook genome sequencing and annotation, gene expression assays, studies of plant cell wall degrading enzymes, and other functional and comparative studies of the Asian longhorned beetle, Anoplophora glabripennis, a globally significant invasive species capable of inflicting severe feeding damage on many important tree species. Complementary studies of genes encoding enzymes involved in digestion of woody plant tissues or detoxification of plant allelochemicals were undertaken with the genomes of 14 additional insects, including the newly sequenced emerald ash borer and bull-headed dung beetle. The Asian longhorned beetle genome encodes a uniquely diverse arsenal of enzymes that can degrade the main polysaccharide networks in plant cell walls, detoxify plant allelochemicals, and otherwise facilitate feeding on woody plants. It has the metabolic plasticity needed to feed on diverse plant species, contributing to its highly invasive nature. Large expansions of chemosensory genes involved in the reception of pheromones and plant kairomones are consistent with the complexity of chemical cues it uses to find host plants and mates. Amplification and functional divergence of genes associated with specialized feeding on plants, including genes originally obtained via horizontal gene transfer from fungi and bacteria, contributed to the addition, expansion, and enhancement of the metabolic repertoire of the Asian longhorned beetle, certain other phytophagous beetles, and to a lesser degree, other phytophagous insects. Our results thus begin to establish a genomic basis for the evolutionary success of beetles on plants.

  14. Characteristics of diurnal pattern of global photosynthetically-active ...

    African Journals Online (AJOL)

    A two year data (September 1992 August 1994) on photosynhetically-active radiation (PAR) measured at Ilorin (Lat.: 832´N. Long.:434´E) using LI-190SA quantum sensor are analysed both on daily and monthly mean diurnal bases. This was done with the aim of characterizing the diurnal pattern of this radiation at this ...

  15. Analysis of the nexus between population, water resources and Global Food Security highlights significance of governance and research investments and policy priorities.

    Science.gov (United States)

    Yunusa, Isa A M; Zerihun, Ayalsew; Gibberd, Mark R

    2018-05-10

    Analyses of sensitivity of Global Food Security (GFS) score to a key set of supply or demand factors often suggest population and water supply as being the most critical and on which policies tend to focus. To explore other policy options, we characterised the nexus between GFS and a set of supply or demand factors including defining including population, agricultural and industrial water-use, agricultural publications (as a surrogate for investment in agricultural research and development [R&D]), and corruption perception index (CPI), to reveal opportunities for attaining enduring GFS. We found that despite being the primary driver of demand for food, population showed no significant correlation with GFS scores. Similarly agricultural water-use was poorly correlated with GFS scores, except in countries where evaporation exceeds precipitation and irrigation is significant. However, GFS had a strong positive association with industrial water-use as a surrogate for overall industrialisation. Recent expansions in cultivated land area failed to yield concomitant improvements in GFS score since such expansions have been mostly into marginal lands with low productivity and also barely compensated for lands retired from cropping in several developed economies. However, GFS was positively associated with agricultural R&D investments, as it was with the CPI scores. The apparent and relative strengths of these drivers on GFS outcome amongst countries were in the order: industrial water-use ≈ publication rate ≈ corruption perception > agricultural water-use > population. We concluded by suggesting that to enshrine enduring food security, policies should prioritise (1) increased R&D investments that address farmer needs, and (2) governance mechanisms that promote accountability in both research and production value chains. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  16. REPEATED MEASURES ANALYSIS OF CHANGES IN PHOTOSYNTHETIC EFFICIENCY IN SOUR CHERRY DURING WATER DEFICIT

    Directory of Open Access Journals (Sweden)

    Marija Viljevac

    2012-06-01

    Full Text Available The objective of this study was to investigate changes in photosynthetic efficiency applying repeated measures ANOVA using the photosynthetic performance index (PIABS of the JIP-test as a vitality parameter in seven genotypes of sour cherry (Prunus cerasus, L. during 10 days of continuous water deficit. Both univariate and multivariate ANOVA repeated measures revealed highly significant time effect (Days and its subsequent interactions with genotype and water deficit. However, the multivariate Pillai’s trace test detected the interaction Time × Genotype × Water deficit as not significant. According to the Tukey’s Studentized Range (HSD test, differences between the control and genotypes exposed to water stress became significant on the fourth day of the experiment, indicating that the plants on the average, began to lose their photosynthetic efficiency four days after being exposed to water shortage. It corroborates previous findings in other species that PIABS is very sensitive tool for detecting drought stress.

  17. The effect of temperature on photosynthetic induction under fluctuating light in Chrysanthemum morifolium

    DEFF Research Database (Denmark)

    Öztürk, Isik; Ottosen, Carl-Otto; Ritz, Christian

    2013-01-01

    for photosynthetic induction. Gas exchange measurements were used to investigate the rate of induction and the opening of stomata. It was determined that induction equilibrium for C. morifolium at varying temperatures under dynamic light conditions was reached within 15 to 45 minutes except at saturating light...... intensity. For the same photon irradiance, the momentary state of induction equilibrated was higher approximately at 30° C and it decreased as temperature increased. The interaction effect of irradiance and temperature on induction equilibrium was not significant. The rate of photosynthetic induction...... and the time that it reached its 90% value (t90) was influenced by irradiance significantly. The light history of a leaf had a significant effect on t90, which indicated that an equilibrium state of induction will not always be reached within the same time. The effect of temperature on photosynthetic induction...

  18. Improving sensitivity of linear regression-based cell type-specific differential expression deconvolution with per-gene vs. global significance threshold.

    Science.gov (United States)

    Glass, Edmund R; Dozmorov, Mikhail G

    2016-10-06

    The goal of many human disease-oriented studies is to detect molecular mechanisms different between healthy controls and patients. Yet, commonly used gene expression measurements from blood samples suffer from variability of cell composition. This variability hinders the detection of differentially expressed genes and is often ignored. Combined with cell counts, heterogeneous gene expression may provide deeper insights into the gene expression differences on the cell type-specific level. Published computational methods use linear regression to estimate cell type-specific differential expression, and a global cutoff to judge significance, such as False Discovery Rate (FDR). Yet, they do not consider many artifacts hidden in high-dimensional gene expression data that may negatively affect linear regression. In this paper we quantify the parameter space affecting the performance of linear regression (sensitivity of cell type-specific differential expression detection) on a per-gene basis. We evaluated the effect of sample sizes, cell type-specific proportion variability, and mean squared error on sensitivity of cell type-specific differential expression detection using linear regression. Each parameter affected variability of cell type-specific expression estimates and, subsequently, the sensitivity of differential expression detection. We provide the R package, LRCDE, which performs linear regression-based cell type-specific differential expression (deconvolution) detection on a gene-by-gene basis. Accounting for variability around cell type-specific gene expression estimates, it computes per-gene t-statistics of differential detection, p-values, t-statistic-based sensitivity, group-specific mean squared error, and several gene-specific diagnostic metrics. The sensitivity of linear regression-based cell type-specific differential expression detection differed for each gene as a function of mean squared error, per group sample sizes, and variability of the proportions

  19. The Carbon and Global Warming Potential Impacts of Organic Farming: Does It Have a Significant Role in an Energy Constrained World?

    Directory of Open Access Journals (Sweden)

    Ralph C. Martin

    2011-01-01

    Full Text Available About 130 studies were analyzed to compare farm-level energy use and global warming potential (GWP of organic and conventional production sectors. Cross cutting issues such as tillage, compost, soil carbon sequestration and energy offsets were also reviewed. Finally, we contrasted E and GWP data from the wider food system. We concluded that the evidence strongly favours organic farming with respect to whole-farm energy use and energy efficiency both on a per hectare and per farm product basis, with the possible exception of poultry and fruit sectors. For GWP, evidence is insufficient except in a few sectors, with results per ha more consistently favouring organic farming than GWP per unit product. Tillage was consistently a negligible contributor to farm E use and additional tillage on organic farms does not appear to significantly deplete soil C. Energy offsets, biogas, energy crops and residues have a more limited role on organic farms compared to conventional ones, because of the nutrient and soil building uses of soil organic matter, and the high demand for organic foods in human markets. If farm E use represents 35% of total food chain E use, improvements shown of 20% or more in E efficiency through organic farm management would reduce food-chain E use by 7% or more. Among other food supply chain stages, wholesale/retail (including cooling and packaging and processing often each contribute 30% or more to total food system E. Thus, additional improvements can be obtained with reduced processing, whole foods and food waste minimization.

  20. Photosynthetic functions of Synechococcus in the ocean microbiomes of diverse salinity and seasons.

    Science.gov (United States)

    Kim, Yihwan; Jeon, Jehyun; Kwak, Min Seok; Kim, Gwang Hoon; Koh, InSong; Rho, Mina

    2018-01-01

    Synechococcus is an important photosynthetic picoplankton in the temperate to tropical oceans. As a photosynthetic bacterium, Synechococcus has an efficient mechanism to adapt to the changes in salinity and light intensity. The analysis of the distributions and functions of such microorganisms in the ever changing river mouth environment, where freshwater and seawater mix, should help better understand their roles in the ecosystem. Toward this objective, we have collected and sequenced the ocean microbiome in the river mouth of Kwangyang Bay, Korea, as a function of salinity and temperature. In conjunction with comparative genomics approaches using the sequenced genomes of a wide phylogeny of Synechococcus, the ocean microbiome was analyzed in terms of their composition and clade-specific functions. The results showed significant differences in the compositions of Synechococcus sampled in different seasons. The photosynthetic functions in such enhanced Synechococcus strains were also observed in the microbiomes in summer, which is significantly different from those in other seasons.

  1. Large sensitivity in land carbon storage due to geographical and temporal variation in the thermal response of photosynthetic capacity.

    Science.gov (United States)

    Mercado, Lina M; Medlyn, Belinda E; Huntingford, Chris; Oliver, Rebecca J; Clark, Douglas B; Sitch, Stephen; Zelazowski, Przemyslaw; Kattge, Jens; Harper, Anna B; Cox, Peter M

    2018-06-01

    Plant temperature responses vary geographically, reflecting thermally contrasting habitats and long-term species adaptations to their climate of origin. Plants also can acclimate to fast temporal changes in temperature regime to mitigate stress. Although plant photosynthetic responses are known to acclimate to temperature, many global models used to predict future vegetation and climate-carbon interactions do not include this process. We quantify the global and regional impacts of biogeographical variability and thermal acclimation of temperature response of photosynthetic capacity on the terrestrial carbon (C) cycle between 1860 and 2100 within a coupled climate-carbon cycle model, that emulates 22 global climate models. Results indicate that inclusion of biogeographical variation in photosynthetic temperature response is most important for present-day and future C uptake, with increasing importance of thermal acclimation under future warming. Accounting for both effects narrows the range of predictions of the simulated global land C storage in 2100 across climate projections (29% and 43% globally and in the tropics, respectively). Contrary to earlier studies, our results suggest that thermal acclimation of photosynthetic capacity makes tropical and temperate C less vulnerable to warming, but reduces the warming-induced C uptake in the boreal region under elevated CO 2 . © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

  2. Effects of salt and water stress on plant biomass and photosynthetic ...

    African Journals Online (AJOL)

    Water deficit led to earlier peaks of net photosynthetic rate (PN) during the day. Relative rate of electron transport (ETR) decreased, but optimal quantum yield of photosystem II (Fv/Fm) showed no significant difference (P<0.05) with water deficit (from 60 to 20% FC); soil salt significantly decreased PN and transpiration rate ...

  3. Photosynthetic Rates of Citronella and Lemongrass 1

    Science.gov (United States)

    Herath, H. M. Walter; Ormrod, Douglas P.

    1979-01-01

    Ten selections of citronella (Cymbopogon nardus [L.] Rendle) were grown at 32/27, 27/21, or 15/10 C day/night temperatures, and plants from three populations of lemongrass (Cymbopogon citratus [D.C.] Stapf from Japan or Sri Lanka and Cymbopogon flexuosus [D.C.] Stapf from India) were grown at 8- or 15-hour photoperiods. Net photosynthetic rates of mature leaves were measured in a controlled environment at 25 C and 260 microeinsteins per meter2 per second. Rates declined with increasing leaf age, and from the tip to the base of the leaf blade. Rates for citronella leaves grown at 15/10 C were extremely low for all selections. Highest rates of net photosynthesis were recorded for four selections grown at 27/21 C and for two selections grown at 32/27 C. Lemongrass grown at 8-hour photoperiod had higher photosynthetic rates than that grown at 15-hour photoperiod. PMID:16660737

  4. BOREAS TE-9 NSA Photosynthetic Response Data

    Science.gov (United States)

    Hall, Forrest G.; Curd, Shelaine (Editor); Dang, Qinglai; Margolis, Hank; Coyea, Marie

    2000-01-01

    The Boreal Ecosystem-Atmospheric Study (BOREAS) TE-9 (Terrestrial Ecology) team collected several data sets related to chemical and photosynthetic properties of leaves. This data set describes: (1) the response of leaf and shoot-level photosynthesis to ambient and intercellular CO2 concentration, temperature, and incident photosynthetically active radiation (PAR) for black spruce, jack pine, and aspen during the three intensive field campaigns (IFCs) in 1994 in the Northern Study Area (NSA); (2) the response of stomatal conductance to vapor pressure difference throughout the growing season of 1994; and (3) a range of shoot water potentials (controlled in the laboratory) for black spruce and jack pine. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  5. Seasonal changes in photosynthetic capacity of leaves of kiwifruit (Actinidia deliciosa) vines

    International Nuclear Information System (INIS)

    Buwalda, J.G.; Meekings, J.S.; Smith, G.S.

    1991-01-01

    The seasonal trend of photosynthetic capacity of leaves of kiwifruit (Actinidia deliciosa var. deliciosa) vines growing in the field was examined, by measuring the response of net photosynthesis (A) to irradiance (PAR) at monthly intervals for leaves that emerged at different stages of the growing season. A climate controlled minicuvette system was used, to ensure constant environmental conditions, apart from the controlled changes in leaf irradiance. Responses of A to irradiance were described using asymptotic exponential curves, providing estimates of the radiation saturated rate of A (A sat ), and the response of A to increasing incident PAR at low PAR levels (ϕ i ). The change in photosynthetic capacity with leaf age was similar for leaves emerging 1, 2, 3 or 4 months after bud burst. At 1 month after leaf emergence, when leaves were fully expanded, Asat was 9–11 μmol CO 2 m −2 s −1 . Maximum photosynthetic capacity was not attained until 3–5 months after leaf emergence, when Asat was 16–17 μmol CO 2 m −2 s −1 . The increasing photosynthetic capacity during 3–5 months after leaf emergence was closely related to concomitant changes in leaf N and chlorophyll contents. The possibility that N import to the leaf was a significant factor limiting the development of photosynthetic capacity is discussed. (author)

  6. Ionizing radiation and photosynthetic ability of cyanobacteria

    International Nuclear Information System (INIS)

    Agarwal, Rachna; Sainis, Jayashree K.

    2006-01-01

    Unicellular photoautotrophic cyanobacteria, Anacystis nidulans when exposed to lethal dose of 1.5 kGy of 60 Co γ- radiation (D 10 = 257.32 Gy) were as effective photosynthetical as unirradiated controls immediately after irradiation although level of ROS was higher by several magnitudes in these irradiated cells. The results suggested the preservation of the functional integrity of thylakoids even after exposure to lethal dose of ionizing radiation. (author)

  7. Nitrogen control of photosynthetic protein synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, G.W.

    1986-09-01

    Plant growth is severely affected by impaired photosynthesis resulting from nitrogen deficiency. The molecular aspects of this effect are being studied in the green alga Chlamydomonas grown in continuous culture systems. Photosynthetic membranes of nitrogen-limited cells are dramatically depleted in chlorophylls, xanthophylls and proteins of the light-harvesting complexes. In contrast, enzymes of the reductive pentose phosphate cycle and electron transport chain complexes are reduced only 40 to 65% on a per cell basis comparison with nitrogen-sufficient cultures. From analyses of mRNA levels by in vitro translation and hybridization analyses with cloned DNA sequences for photosynthetic proteins, we have found there are rather minor effects of nitrogen deficiency on nuclear or chloroplast gene transcription. Maturation of a transcript of the nuclear-encoded small subunit of ribulose 1,5-bisphosphate carboxylase is inhibited in nitrogen-deficient cells and causes accumulation of large amounts of mRNA precursors. Most of the effects of nitrogen deficiency on photosynthetic proteins appear to result from posttranscriptional regulatory processes: light-harvesting protein synthesis may be sustained but their import into chloroplasts or translocation to photosynthetic membranes is impaired. Nitrogen-deficient cells lack violaxanthin, a pigment that is essential for the structure, function and biogenesis of the major antenna complexes. The absence of this pigment may be a causative factor for the deficiency of light harvesting complexes. Finally, the accumulation of massive amounts of starch and triglycerides in nitrogen-limited cells indicate there are some genes whose maximal expression is dependent upon nitrogen-limiting conditions. 10 refs.

  8. Photosynthetic capacity of tropical montane tree species in relation to leaf nutrients, successional strategy and growth temperature.

    Science.gov (United States)

    Dusenge, Mirindi Eric; Wallin, Göran; Gårdesten, Johanna; Niyonzima, Felix; Adolfsson, Lisa; Nsabimana, Donat; Uddling, Johan

    2015-04-01

    Photosynthetic capacity of tree leaves is typically positively related to nutrient content and little affected by changes in growth temperature. These relationships are, however, often poorly supported for tropical trees, for which interspecific differences may be more strongly controlled by within-leaf nutrient allocation than by absolute leaf nutrient content, and little is known regarding photosynthetic acclimation to temperature. To explore the influence of leaf nutrient status, successional strategy and growth temperature on the photosynthetic capacity of tropical trees, we collected data on photosynthetic, chemical and morphological leaf traits of ten tree species in Rwanda. Seven species were studied in a forest plantation at mid-altitude (~1,700 m), whereas six species were studied in a cooler montane rainforest at higher altitude (~2,500 m). Three species were common to both sites, and, in the montane rainforest, three pioneer species and three climax species were investigated. Across species, interspecific variation in photosynthetic capacity was not related to leaf nutrient content. Instead, this variation was related to differences in within-leaf nitrogen allocation, with a tradeoff between investments into compounds related to photosynthetic capacity (higher in pioneer species) versus light-harvesting compounds (higher in climax species). Photosynthetic capacity was significantly lower at the warmer site at 1,700 m altitude. We conclude that (1) within-leaf nutrient allocation is more important than leaf nutrient content per se in controlling interspecific variation in photosynthetic capacity among tree species in tropical Rwanda, and that (2) tropical montane rainforest species exhibit decreased photosynthetic capacity when grown in a warmer environment.

  9. PS2013 Satellite Workshop on Photosynthetic Light-Harvesting Systems

    Energy Technology Data Exchange (ETDEWEB)

    Niederman, Robert A. [Rutgers Univ., New Brunswick, NJ (United States); Blankenship, Robert E. [Washington Univ., St. Louis, MO (United States); Frank, Harry A. [Univ. of Connecticut, Storrs, CT (United States)

    2015-02-07

    These funds were used for partial support of the PS2013 Satellite Workshop on Photosynthetic Light-Harvesting Systems, that was held on 8-11 August, 2013, at Washington University, St. Louis, MO. This conference, held in conjunction with the 16th International Congress on Photosynthesis/St. Louis, continued a long tradition of light-harvesting satellite conferences that have been held prior to the previous six international photosynthesis congresses. In this Workshop, the basis was explored for the current interest in replacing fossil fuels with energy sources derived form direct solar radiation, coupled with light-driven electron transport in natural photosynthetic systems and how they offer a valuable blueprint for conversion of sunlight to useful energy forms. This was accomplished through sessions on the initial light-harvesting events in the biological conversion of solar energy to chemically stored energy forms, and how these natural photosynthetic processes serve as a guide to the development of robust bio-hybrid and artificial systems for solar energy conversion into both electricity or chemical fuels. Organized similar to a Gordon Research Conference, a lively, informal and collegial setting was established, highlighting the exchange of exciting new data and unpublished results from ongoing studies. A significant amount of time was set aside for open discussion and interactive poster sessions, with a special session devoted to oral presentations by talented students and postdoctoral fellows judged to have the best posters. This area of research has seen exceptionally rapid progress in recent years, with the availability of a number of antenna protein structures at atomic resolution, elucidation of the molecular surface architecture of native photosynthetic membranes by atomic force microscopy and the maturing of ultrafast spectroscopic and molecular biological techniques for the investigation and manipulation of photosynthetic systems. The conferees

  10. Pre-aged soil organic carbon as a major component of the Yellow River suspended load: Regional significance and global relevance

    Science.gov (United States)

    Tao, Shuqin; Eglinton, Timothy I.; Montluçon, Daniel B.; McIntyre, Cameron; Zhao, Meixun

    2015-03-01

    Large rivers connect the continents and the oceans, and corresponding material fluxes have a global impact on marine biogeochemistry. The Yellow River transports vast quantities of suspended sediments to the ocean, yet the nature of the particulate organic carbon (POC) carried by this system is not well known. The focus of this study is to characterize the sources, composition and age of suspended POC collected near the terminus of this river system, focusing on the abundance and carbon isotopic composition (13C and 14C) of specific biomarkers. The concentrations of vascular plant wax lipids (long-chain (≥C24) n-alkanes, n-fatty acids) and POC co-varied with total suspended solid (TSS) concentrations, indicating that both were controlled by the overall terrestrial sediment flux. POC exhibited relatively uniform δ13C values (-23.8 to -24.2‰), and old radiocarbon ages (4000-4640 yr). However, different biomarkers exhibited a wide range of 14C ages. Short-chain (C16, C18) fatty acid 14C ages were variable but generally the youngest organic components (from 502 yr to modern), suggesting they reflect recently biosynthesized material. Lignin phenol 14C ages were also variable and relatively young (1070 yr to modern), suggesting rapid export of carbon from terrestrial primary production. In contrast, long-chain plant wax lipids display relatively uniform and significantly older 14C ages (1500-1800 yr), likely reflecting inputs of pre-aged, mineral-associated soil OC from the Yellow River drainage basin. Even-carbon-numbered n-alkanes yielded the oldest 14C ages (up to 26 000 yr), revealing the presence of fossil (petrogenic) OC. Two isotopic mass balance approaches were explored to quantitively apportion different OC sources in Yellow River suspended sediments. Results indicate that the dominant component of POC (53-57%) is substantially pre-aged (1510-1770 yr), and likely sourced from the extensive loess-paleosol deposits outcropping within the drainage basin. Of

  11. Photosynthetic light response of the C4 grasses Brachiaria brizantha and B. humidicola under shade

    Directory of Open Access Journals (Sweden)

    Dias-Filho Moacyr Bernardino

    2002-01-01

    Full Text Available Forage grasses in tropical pastures can be subjected to considerable diurnal and seasonal reductions in available light. To evaluate the physiological behavior of the tropical forage grasses Brachiaria brizantha cv. Marandu and B. humidicola to low light, the photosynthetic light response and chlorophyll contents of these species were compared for plants grown outdoors, on natural soil, in pots, in full sunlight and those shaded to 30 % of full sunlight, over a 30-day period. Both species showed the ability to adjust their photosynthetic behavior in response to shade. Photosynthetic capacity and light compensation point were lower for shade plants of both species, while apparent quantum yield was unaffected by the light regime. Dark respiration and chlorophyll a:b ratio were significantly reduced by shading only in B. humidicola. B. humidicola could be relatively more adapted to succeed, at least temporarily, in light-limited environments.

  12. Effects of salinity and short-term elevated atmospheric CO2 on the chemical equilibrium between CO2 fixation and photosynthetic electron transport of Stevia rebaudiana Bertoni.

    Science.gov (United States)

    Hussin, Sayed; Geissler, Nicole; El-Far, Mervat M M; Koyro, Hans-Werner

    2017-09-01

    The effect of water salinity on plant growth and photosynthetic traits of Stevia rebaudiana was investigated to determine its level and mechanisms of salinity tolerance. It was also attempted to assess how short-term elevated CO 2 concentration would influence the boundaries and mechanisms of its photosynthetic capacity. The plants were grown in gravel/hydroponic system under controlled greenhouse conditions and irrigated with four different salinity levels (0, 25, 50 and 100 mol m -3 NaCl). Low salinity did not significantly alter the plant fresh weight, which was substantially decreased by 67% at high salinity treatment. Salinity tolerance threshold was reached at 50 mol m -3  NaCl while C50 was between 50 and 100 mol m -3  NaCl, indicating that S. rebaudiana is a moderate salt tolerant species. Salt-induced growth reduction was apparently linked to a significant decline of about 47% in the photosynthetic rates (A net ) at high salinity treatment, leading consequently to a disequilibrium between CO 2 -assimilation and electron transport rates (indicated by enhanced ETR max /A gross ratio). Elevated atmospheric CO 2 enhanced CO 2 assimilation rates by 65% and 80% for control and high-salt-stressed plants respectively, likely due to significant increases in intercellular CO 2 concentration (indicated by enhanced C i /C a ). The priority for Stevia under elevated atmospheric CO 2 was not to save water but to maximize photosynthesis so that the PWUE was progressively improved and the threat of oxidative stress was diminished (decline in ETR max /A gross ). The results imply that elevated CO 2 level could ameliorate some of the detrimental effects of salinity, conferring higher tolerance and survival of S. rebaudiana, a highlydesired feature with the forthcoming era of global changes. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  13. Changes of Photosynthetic Behaviors in Kappaphycus alvarezii Infected by Epiphyte

    Directory of Open Access Journals (Sweden)

    Tong Pang

    2011-01-01

    Full Text Available Epiphytic filamentous algae (EFA were noted as a serious problem to reduce the production and quality of K. alvarezii. The morphological studies revealed that the main epiphyte on K. alvarezii was Neosiphonia savatieri in China. Though the harmful effects of EFA on the production of K. alvarezii have been reported, the detailed mechanism of the N. savatieri in limiting the production of K. alvarezii has not been studied yet. The present paper studied the effects of N. savatieri infection on photosynthetic behaviors in K. alvarezii by detecting chlorophyll fluorescence transient in vivo. The results revealed that damage of oxygen-evolving complex (OEC, decrease of active reaction centers (RCs, and the plastoquinone (PQ pool as well as significant reduction in the performance indexes (PI of PSII were caused by the infection of N. savatieri. The influence of N. savatieri on photosynthetic activity of K. alvarezii should be one of the important reasons to reduce the production of K. alvarezii infected by N. savatieri.

  14. Difference in leaf water use efficiency/photosynthetic nitrogen use efficiency of Bt-cotton and its conventional peer.

    Science.gov (United States)

    Guo, Ruqing; Sun, Shucun; Liu, Biao

    2016-09-15

    This study is to test the effects of Bt gene introduction on the foliar water/nitrogen use efficiency in cotton. We measured leaf stomatal conductance, photosynthetic rate, and transpiration rate under light saturation condition at different stages of a conventional cultivar (zhongmian no. 16) and its counterpart Bt cultivar (zhongmian no. 30) that were cultured on three levels of fertilization, based on which leaf instantaneous water use efficiency was derived. Leaf nitrogen concentration was measured to calculate leaf photosynthetic nitrogen use efficiency, and leaf δ(13)C was used to characterize long term water use efficiency. Bt cultivar was found to have lower stomatal conductance, net photosynthetic rates and transpiration rates, but higher instantaneous and long time water use efficiency. In addition, foliar nitrogen concentration was found to be higher but net photosynthetic rate was lower in the mature leaves of Bt cultivar, which led to lower photosynthetic nitrogen use efficiency. This might result from the significant decrease of photosynthetic rate due to the decrease of stomatal conductance. In conclusion, our findings show that the introduction of Bt gene should significantly increase foliar water use efficiency but decrease leaf nitrogen use efficiency in cotton under no selective pressure.

  15. [Photosynthetic rate, transpiration rate, and water use efficiency of cotton canopy in oasis edge of Linze].

    Science.gov (United States)

    Xie, Ting-Ting; Su, Pei-Xi; Gao, Song

    2010-06-01

    The measurement system of Li-8100 carbon flux and the modified assimilation chamber were used to study the photosynthetic characteristics of cotton (Gossypium hirsutum L.) canopy in the oasis edge region in middle reach of Heihe River Basin, mid Hexi Corridor of Gansu. At the experimental site, soil respiration and evaporation rates were significantly higher in late June than in early August, and the diurnal variation of canopy photosynthetic rate showed single-peak type. The photosynthetic rate was significantly higher (P transpiration rate also presented single-peak type, with the daily average value in late June and early August being (3.10 +/- 0.34) mmol H2O x m(-2) x s(-1) and (1.60 +/- 0.26) mmol H2O x m(-2) x s(-1), respectively, and differed significantly (P efficiency in late June and early August was (15.67 +/- 1.77) mmol CO2 x mol(-1) H2O and (23.08 +/- 5.54) mmol CO2 x mol(-1) H2O, respectively, but the difference was not significant (P > 0.05). Both in late June and in early August, the canopy photosynthetic rate was positively correlated with air temperature, PAR, and soil moisture content, suggesting that there was no midday depression of photosynthesis in the two periods. In August, the canopy photosynthetic rate and transpiration rate decreased significantly, because of the lower soil moisture content and leaf senescence, but the canopy water use efficiency had no significant decrease.

  16. Non-destructive determination of photosynthetic rates of eight varieties of cassava (Manihot esculenta Crantz)

    International Nuclear Information System (INIS)

    Amadu, A. A.

    2015-07-01

    Cassava is an important food security crop in Ghana and in the wake of climate change there is the need for plant breeders to develop varieties with high water use efficiency as well as high photosynthetic rate in order to adapt to the changing climate. Thus, the photosynthetic rates of eight cassava (Manihot esculenta Crantz) varieties were non-destructively evaluated using photosynthesis meter miniPPM300, from June 2014 to May 2015, with the aim of selecting varieties with high photosynthetic rate for future breeding programmes. The mean photosynthetic rate varied depending on the varieties ranging from 40.5 μmol/m 2 s in Bosom nsia to 45.2 μmol/m 2 s in Gbenze. However, the presence of African cassava mosaic disease (ACMD) marginally reduced the photosynthetic rate to below 40 μmol/m 2 s in all the varieties. Similarly, the chlorophyll content index (CCI) as measured by chlorophyll meter and spectrophotometer also varied from one variety to another; it was low in Nandom (17.9 CCI) and high in Gbenze (39.93 CCI) using the chlorophyll meter and was also reduced by the presence of the virus. Although, the stomatal density varied between the varieties it was not influenced by virus infection. Furthermore, ACMD significantly decreased the leaf surface area from 5705.8mm 2 in uninfected plants to 1251.6mm 2 in infected plants, consequently reducing the number and weight of tubers produced 11 month after planting (MAP). Molecular Testing of the viruses using virus specific primers JSP001/JSP002, EAB555F/EAB555R, EACMV1e/EACMV2e at 6 MAP and 11MAP, showed that the mosaic symptoms were caused by African Cassava Mosaic virus disease. Cassava varieties with high photosynthetic efficiency and low virus infection can be used in cassava improvement programmes in Ghana. (au)

  17. Contrasting Responses of Marine and Freshwater Photosynthetic Organisms to UVB Radiation: A Meta-Analysis

    KAUST Repository

    Jin, Peng

    2017-03-14

    Ultraviolet-B (UVB) radiation is a global stressor that has profound impacts on freshwater and marine ecosystems. However, an analysis of the patterns of sensitivity to UVB radiation across aquatic photosynthetic organisms has not yet been published. Here, we performed a meta-analysis on results reported in 214 studies compiled from the published literature to quantify and compare the magnitude of responses of aquatic photosynthetic organisms to changes in UVB radiation. The meta-analysis was conducted on observations of marine (n = 893) and freshwater macroalgae (n = 126) and of marine (n = 1,087) and freshwater (n = 2,889) microalgae (total n = 4,995). Most of these studies (85%) analyzed the performance of organisms exposed to natural solar radiation when UVB was partially or totally reduced compared with the organismal performance under the full solar radiation spectrum, whereas the remaining 15% of the studies examined the responses of organisms to elevated UVB radiation mostly using artificial lamps. We found that marine photosynthetic organisms tend to be more sensitive than freshwater photosynthetic organisms to UVB radiation; responses to either decreased or increased UVB radiation vary among taxa; the mortality rate is the most sensitive of the trait responses to elevated UVB radiation, followed by changes in cellular and molecular traits; the sensitivity of microalgae to UVB radiation is dependent on size, with small-celled microalgae more sensitive than large-celled microalgae to UVB radiation. Thick macroalgae morphotypes were the less sensitive to UVB, but this effect could not be separated from phylogenetic differences. The high sensitivity of marine species, particularly the smallest photosynthetic organisms, to increased UVB radiation suggests that the oligotrophic ocean, a habitat comprising 70% of the world\\'s oceans with high UVB penetration and dominated by picoautotrophs, is extremely vulnerable to changes in UVB radiation.

  18. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Gregory Kremer; Dr. David J. Bayless; Dr. Morgan Vis; Dr. Michael Prudich; Dr. Keith Cooksey; Dr. Jeff Muhs

    2002-07-15

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 4/2/2001 through 7/01/2002. Most of the achievements are milestones in our efforts to complete the tasks and subtasks that constitute the project objectives, and we are currently on schedule to complete Phase I activities by 10/2002, the milestone date from the original project timeline. As indicated in the list of accomplishments below, our efforts are focused on improving the design of the bioreactor test system, evaluating candidate organisms and growth surfaces, and scaling-up the test facilities from bench scale to pilot scale. Specific results and accomplishments for the second quarter of 2002 include: Organisms and Growth Surfaces: (1) Our collection of cyanobacteria, isolated in YNP was increased to 15 unialgal cultures. (2) Illumination rate about 50 {micro}E/m{sup 2}/sec is not saturated for the growth of 1.2 s.c. (2) isolate. The decrease of illumination rate led to the decrease of doubling time of this isolate. (3) The positive effect of Ca{sup 2+} on the growth of isolate 1.2 s.c. (2) without Omnisil was revealed, though Ca{sup 2+} addition was indifferent for the growth of this isolate at the presence of Omnisil. (4) Calcium addition had a positive effect on the generation of cyanobacterial biofilm on Omnisil surface. (5) The survivability problems with the Tr9.4 organism on Omnisil screens in the CRF2 model-scale bioreactor have been solved. The problems were related to the method used to populate the growth surfaces. When pre-populated screens were placed in the bioreactor the microalgae died within 72 hours, but when the microalgae were cultured while in place in the bioreactor using a continuous-population method they grew well inside of the CRF2 test system and survived for the full 7-day test duration. CRF2 tests will continue as soon as the new combined drip system/harvesting system header pipe

  19. Photosynthetic accessory pigments: evidence for the influence of phycoerythrin on the submarine light field

    International Nuclear Information System (INIS)

    Hoge, F.E.; Swift, R.N.

    1990-01-01

    Oceanic phytoplankton chlorophyll is known to produce a very significant influence on the optical properties of the ocean. The chlorophyll-driven optical properties are in fact so strong as to allow global satellite mapping of the pigment concentration in the upper ocean using upwelled waterleaving radiances. In this paper, extensive experimental evidence is presented to strongly suggest that upwelled water-leaving spectral radiances (and therefore the submarine light field source) also include physical scattering and absorption effects of photosynthetic accessory pigments such as phycoerythrin. In the water column, the presence of phycoerythrin was measured over wide regions of the ocean using well-established airborne laser-induced spectral fluorescence techniques. Active-passive correlation spectroscopy methods revealed that concurrently measured water-leaving spectral radiances in the ∼ 600 nm spectral region were highly correlated with the laser-induced phycoerythrin pigment fluorescence. The analysis was performed on data sets in which the phycoerythrin and chlorophyll fluorescence were not coherent in order to permit the unambiguous evaluation of results. (author)

  20. Magnetic irone oxide nanoparticles in photosynthetic systems

    International Nuclear Information System (INIS)

    Khalilov, R.I.; Nasibova, A.N.; Khomutov, G.B.

    2014-01-01

    Full text : It was found and studied the effect of biogenic formation of magnetic inclusions in photosynthetic systems - in various higher plants under the influence of some external stress factors (radiation impact, moisture deficit) and in a model system - a suspension of chloroplasts. For registration and characterization of magnetic nanoparticles in the samples used EPR spectrometer because superparamagnetic and ferromagnetic nanoparticles have a chcracteristic signals of electron magnetic resonance. For direct visualization of magnetic nanoparticles it was used the method of transmission electron microscopy

  1. Engineering cyanobacteria as photosynthetic feedstock factories.

    Science.gov (United States)

    Hays, Stephanie G; Ducat, Daniel C

    2015-03-01

    Carbohydrate feedstocks are at the root of bioindustrial production and are needed in greater quantities than ever due to increased prioritization of renewable fuels with reduced carbon footprints. Cyanobacteria possess a number of features that make them well suited as an alternative feedstock crop in comparison to traditional terrestrial plant species. Recent advances in genetic engineering, as well as promising preliminary investigations of cyanobacteria in a number of distinct production regimes have illustrated the potential of these aquatic phototrophs as biosynthetic chassis. Further improvements in strain productivities and design, along with enhanced understanding of photosynthetic metabolism in cyanobacteria may pave the way to translate cyanobacterial theoretical potential into realized application.

  2. Culturing photosynthetic bacteria through surface plasmon resonance

    Energy Technology Data Exchange (ETDEWEB)

    Ooms, Matthew D.; Bajin, Lauren; Sinton, David [Department of Mechanical and Industrial Engineering and Centre for Sustainable Energy, University of Toronto, Toronto M5S 3G8 (Canada)

    2012-12-17

    In this work, cultivation of photosynthetic microbes in surface plasmon enhanced evanescent fields is demonstrated. Proliferation of Synechococcus elongatus was obtained on gold surfaces excited with surface plasmons. Excitation over three days resulted in 10 {mu}m thick biofilms with maximum cell volume density of 20% vol/vol (2% more total accumulation than control experiments with direct light). Collectively, these results indicate the ability to (1) excite surface-bound cells using plasmonic light fields, and (2) subsequently grow thick biofilms by coupling light from the surface. Plasmonic light delivery presents opportunities for high-density optofluidic photobioreactors for microalgal analysis and solar fuel production.

  3. Temporal Variations in the Photosynthetic Biosphere

    Science.gov (United States)

    Behrenfeld, Michael; Randerson, James; McClain, Charles; Feldman, Gene; Los, Sietse; Tucker, Compton; Falkowski, Paul; Field, Christopher; Frouin, Robert; Esaias, Wayne; hide

    2000-01-01

    In this report, we describe results from the first three years of global Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) ocean chlorophyll and land plant measurements. This time period covered the end of one of the largest El Nino events in the past century and a strong La Nina. During this transition, terrestrial plant photosynthesis exhibited only a small change, whereas a significant increase in oceanic photosynthesis was observed. Latitudinal distributions of ocean production indicated that this increase in photosynthesis during the La Nina was distributed in the equatorial belt as well as in high production areas. The analysis also illustrated the large 'missing bloom' in ocean phytoplankton in the southern ocean. While land photosynthesis remained fairly steady during the third year of SeaWiFS measurements, ocean phytoplankton production continued to increase, albeit at a lower rate than from 1997 to 1999. Our results represent the first quantification of interannual variability in global scale ocean productivity. Significant Findings: An increase in ocean production during the first three years of the SeaWiFS mission; a strong hemispheric difference in the latitudinal distribution of ocean photosynthesis.

  4. Redox regulation of photosynthetic gene expression.

    Science.gov (United States)

    Queval, Guillaume; Foyer, Christine H

    2012-12-19

    Redox chemistry and redox regulation are central to the operation of photosynthesis and respiration. However, the roles of different oxidants and antioxidants in the regulation of photosynthetic or respiratory gene expression remain poorly understood. Leaf transcriptome profiles of a range of Arabidopsis thaliana genotypes that are deficient in either hydrogen peroxide processing enzymes or in low molecular weight antioxidant were therefore compared to determine how different antioxidant systems that process hydrogen peroxide influence transcripts encoding proteins targeted to the chloroplasts or mitochondria. Less than 10 per cent overlap was observed in the transcriptome patterns of leaves that are deficient in either photorespiratory (catalase (cat)2) or chloroplastic (thylakoid ascorbate peroxidase (tapx)) hydrogen peroxide processing. Transcripts encoding photosystem II (PSII) repair cycle components were lower in glutathione-deficient leaves, as were the thylakoid NAD(P)H (nicotinamide adenine dinucleotide (phosphate)) dehydrogenases (NDH) mRNAs. Some thylakoid NDH mRNAs were also less abundant in tAPX-deficient and ascorbate-deficient leaves. Transcripts encoding the external and internal respiratory NDHs were increased by low glutathione and low ascorbate. Regulation of transcripts encoding specific components of the photosynthetic and respiratory electron transport chains by hydrogen peroxide, ascorbate and glutathione may serve to balance non-cyclic and cyclic electron flow pathways in relation to oxidant production and reductant availability.

  5. Respiratory processes in non-photosynthetic plastids

    Science.gov (United States)

    Renato, Marta; Boronat, Albert; Azcón-Bieto, Joaquín

    2015-01-01

    Chlororespiration is a respiratory process located in chloroplast thylakoids which consists in an electron transport chain from NAD(P)H to oxygen. This respiratory chain involves the NAD(P)H dehydrogenase complex, the plastoquinone pool and the plastid terminal oxidase (PTOX), and it probably acts as a safety valve to prevent the over-reduction of the photosynthetic machinery in stress conditions. The existence of a similar respiratory activity in non-photosynthetic plastids has been less studied. Recently, it has been reported that tomato fruit chromoplasts present an oxygen consumption activity linked to ATP synthesis. Etioplasts and amyloplasts contain several electron carriers and some subunits of the ATP synthase, so they could harbor a similar respiratory process. This review provides an update on the study about respiratory processes in chromoplasts, identifying the major gaps that need to be addressed in future research. It also reviews the proteomic data of etioplasts and amyloplasts, which suggest the presence of a respiratory electron transport chain in these plastids. PMID:26236317

  6. Respiratory processes in non-photosynthetic plastids

    Directory of Open Access Journals (Sweden)

    Marta eRenato

    2015-07-01

    Full Text Available Chlororespiration is a respiratory process located in chloroplast thylakoids which consists in an electron transport chain from NAD(PH to oxygen. This respiratory chain involves the NAD(PH dehydrogenase complex, the plastoquinone pool and the plastid terminal oxidase (PTOX, and it probably acts as a safety valve to prevent the over-reduction of the photosynthetic machinery in stress conditions. The existence of a similar respiratory activity in non-photosynthetic plastids has been less studied. Recently, it has been reported that tomato fruit chromoplasts present an oxygen consumption activity linked to ATP synthesis. Etioplasts and amyloplasts contain several electron carriers and some subunits of the ATP synthase, so they could harbor a similar respiratory process. This review provides an update on the study about respiratory processes in chromoplasts, identifying the major gaps that need to be addressed in future research. It also reviews the proteomic data of etioplasts and amyloplasts, which suggest the presence of a respiratory electron transport chain in these plastids.

  7. Photosynthetic pathways of some aquatic plants

    Energy Technology Data Exchange (ETDEWEB)

    Hough, R A [Wayne State Univ., Detroit; Wetzel, R G

    1977-12-01

    Over 40 species of aquatic angiosperms, including submersed, floating and emergent types, have been examined for photosynthetic status as part of a search for possible aquatic C/sub 4/ species. The C/sub 4/ system is viewed as potentially of adaptive value in certain aquatic situations, although evidence for its occurrence there is not conclusive. Emphasis was on plants from North-temperate softwater and hardwater lakes to explore both possibilities of CO/sub 2/ limitation, i.e., low total inorganic carbon in softwater vs. low free CO/sub 2/ in hardwater lakes. On the basis of leaf cross-section anatomy, all plants examined, with one exception, clearly did not show evidence of C/sub 4/ ''Krantz anatomy.'' In the submersed plant Potamogeton praelongus Wulf, large starch-producing chloroplasts were concentrated in cells surrounding vascular bundles and in a narrow band of cells between vascular bundles. The in situ photosynthetic rate of this plant was twice that of a related species, but other evidence including PEP carboxylase content and photorespiratory response to high O/sub 2/ did not confirm the presence of the C/sub 4/ photosynthesis.

  8. The effect of nitrogen on the development and photosynthetic activity ...

    African Journals Online (AJOL)

    Whole plant net photosynthetic rates appeared to vary according to the units in which the activity is expressed. The optimum levels of photosynthetic activity differed with the stage of development, depending on the basis of expression. The form and concentration of nitrogen applied influenced morphological development ...

  9. Variations in morphology and PSII photosynthetic capabilities during the early development of tetraspores of Gracilaria vermiculophylla (Ohmi) Papenfuss (Gracilariales, Rhodophyta).

    Science.gov (United States)

    Xie, Xiujun; Wang, Guangce; Pan, Guanghua; Gao, Shan; Xu, Pu; Zhu, Jianyi

    2010-04-28

    Red algae are primitive photosynthetic eukaryotes, whose spores are ideal subjects for studies of photosynthesis and development. Although the development of red alga spores has received considerable research attention, few studies have focused on the detailed morphological and photosynthetic changes that occur during the early development of tetraspores of Gracilaria vermiculophylla (Ohmi) Papenfuss (Gracilariales, Rhodophyta). Herein, we documented these changes in this species of red algae. In the tetraspores, we observed two types of division, cruciate and zonate, and both could develop into multicellular bodies (disks). During the first 84 hours, tetraspores divided several times, but the diameter of the disks changed very little; thereafter, the diameter increased significantly. Scanning electron microscopy observations and analysis of histological sections revealed that the natural shape of the disk remains tapered over time, and the erect frond grows from the central protrusion of the disk. Cultivation of tissue from excised disks demonstrated that the central protrusion of the disk is essential for initiation of the erect frond. Photosynthetic (i.e., PSII) activities were measured using chlorophyll fluorescence analysis. The results indicated that freshly released tetraspores retained limited PSII photosynthetic capabilities; when the tetraspores attached to a substrate, those capabilities increased significantly. In the disk, the PSII activity of both marginal and central cells was similar, although some degree of morphological polarity was present; the PSII photosynthetic capabilities in young germling exhibited an apico-basal gradient. Attachment of tetraspores to a substrate significantly enhanced their PSII photosynthetic capabilities, and triggered further development. The central protrusion of the disk is the growth point, may have transfer of nutritive material with the marginal cells. Within the young germling, the hetero-distribution of PSII

  10. Variations in morphology and PSII photosynthetic capabilities during the early development of tetraspores of Gracilaria vermiculophylla (Ohmi Papenfuss (Gracilariales, Rhodophyta

    Directory of Open Access Journals (Sweden)

    Gao Shan

    2010-04-01

    Full Text Available Abstract Background Red algae are primitive photosynthetic eukaryotes, whose spores are ideal subjects for studies of photosynthesis and development. Although the development of red alga spores has received considerable research attention, few studies have focused on the detailed morphological and photosynthetic changes that occur during the early development of tetraspores of Gracilaria vermiculophylla (Ohmi Papenfuss (Gracilariales, Rhodophyta. Herein, we documented these changes in this species of red algae. Results In the tetraspores, we observed two types of division, cruciate and zonate, and both could develop into multicellular bodies (disks. During the first 84 hours, tetraspores divided several times, but the diameter of the disks changed very little; thereafter, the diameter increased significantly. Scanning electron microscopy observations and analysis of histological sections revealed that the natural shape of the disk remains tapered over time, and the erect frond grows from the central protrusion of the disk. Cultivation of tissue from excised disks demonstrated that the central protrusion of the disk is essential for initiation of the erect frond. Photosynthetic (i.e., PSII activities were measured using chlorophyll fluorescence analysis. The results indicated that freshly released tetraspores retained limited PSII photosynthetic capabilities; when the tetraspores attached to a substrate, those capabilities increased significantly. In the disk, the PSII activity of both marginal and central cells was similar, although some degree of morphological polarity was present; the PSII photosynthetic capabilities in young germling exhibited an apico-basal gradient. Conclusions Attachment of tetraspores to a substrate significantly enhanced their PSII photosynthetic capabilities, and triggered further development. The central protrusion of the disk is the growth point, may have transfer of nutritive material with the marginal cells. Within

  11. Porphyrin and fullerene-based artificial photosynthetic materials for photovoltaics

    International Nuclear Information System (INIS)

    Imahori, Hiroshi; Kashiwagi, Yukiyasu; Hasobe, Taku; Kimura, Makoto; Hanada, Takeshi; Nishimura, Yoshinobu; Yamazaki, Iwao; Araki, Yasuyuki; Ito, Osamu; Fukuzumi, Shunichi

    2004-01-01

    We have developed artificial photosynthetic systems in which porphyrins and fullerenes are self-assembled as building blocks into nanostructured molecular light-harvesting materials and photovoltaic devices. Multistep electron transfer strategy has been combined with our finding that porphyrin and fullerene systems have small reorganization energies, which are suitable for the construction of light energy conversion systems as well as artificial photosynthetic models. Highly efficient photosynthetic electron transfer reactions have been realized at ITO electrodes modified with self-assembled monolayers of porphyrin oligomers as well as porphyrin-fullerene linked systems. Porphyrin-modified gold nanoclusters have been found to have potential as artificial photosynthetic materials. These results provide basic information for the development of nanostructured artificial photosynthetic systems

  12. Morning reduction of photosynthetic capacity before midday depression.

    Science.gov (United States)

    Koyama, Kohei; Takemoto, Shuhei

    2014-03-17

    Midday depression of photosynthesis has important consequences for ecosystem carbon exchange. Recent studies of forest trees have demonstrated that latent reduction of photosynthetic capacity can begin in the early morning, preceding the midday depression. We investigated whether such early morning reduction also occurs in an herbaceous species, Oenothera biennis. Diurnal changes of the photosynthetic light response curve (measured using a light-emitting diode) and incident sunlight intensity were measured under field conditions. The following results were obtained: (1) the light-saturated photosynthetic rate decreased beginning at sunrise; (2) the incident sunlight intensity on the leaves increased from sunrise; and (3) combining (1) and (2), the net photosynthetic rate under natural sunlight intensity increased from sunrise, reached a maximum at mid-morning, and then showed midday depression. Our results demonstrate that the latent morning reduction of photosynthetic capacity begins at sunrise, preceding the apparent midday depression, in agreement with previous studies of forest trees.

  13. Synergistic Utility of Brain Natriuretic Peptide and Left Ventricular Global Longitudinal Strain in Asymptomatic Patients With Significant Primary Mitral Regurgitation and Preserved Systolic Function Undergoing Mitral Valve Surgery.

    Science.gov (United States)

    Alashi, Alaa; Mentias, Amgad; Patel, Krishna; Gillinov, A Marc; Sabik, Joseph F; Popović, Zoran B; Mihaljevic, Tomislav; Suri, Rakesh M; Rodriguez, L Leonardo; Svensson, Lars G; Griffin, Brian P; Desai, Milind Y

    2016-07-01

    In asymptomatic patients with ≥3+ mitral regurgitation and preserved left ventricular (LV) ejection fraction who underwent mitral valve surgery, we sought to discover whether baseline LV global longitudinal strain (LV-GLS) and brain natriuretic peptide provided incremental prognostic utility. Four hundred and forty-eight asymptomatic patients (61±12 years and 69% men) with ≥3+ primary mitral regurgitation and preserved left ventricular ejection fraction, who underwent mitral valve surgery (92% repair) at our center between 2005 and 2008, were studied. Baseline clinical and echocardiographic data (including LV-GLS using Velocity Vector Imaging, Siemens, PA) were recorded. The Society of Thoracic Surgeons score was calculated. The primary outcome was death. Mean Society of Thoracic Surgeons score, left ventricular ejection fraction, mitral effective regurgitant orifice, indexed LV end-diastolic volume, and right ventricular systolic pressure were 4±1%, 62±3%, 0.55±0.2 cm(2), 58±13 cc/m(2), and 37±15 mm Hg, respectively. Forty-five percent of patients had flail. Median log-transformed BNP and LV-GLS were 4.04 (absolute brain natriuretic peptide: 60 pg/dL) and -20.7%. At 7.7±2 years, death occurred in 41 patients (9%; 0% at 30 days). On Cox analysis, a higher Society of Thoracic Surgeons score (hazard ratio 1.55), higher baseline right ventricular systolic pressure (hazard ratio 1.11), more abnormal LV-GLS (hazard ratio 1.17), and higher median log-transformed BNP (hazard ratio 2.26) were associated with worse longer-term survival (all Pright ventricular systolic pressure) provided incremental prognostic utility (χ(2) for longer-term mortality increased from 31-47 to 61; Pleft ventricular ejection fraction who underwent mitral valve surgery, brain natriuretic peptide and LV-GLS provided synergistic risk stratification, independent of established factors. © 2016 American Heart Association, Inc.

  14. Effects of gold nanoparticles on the photophysical and photosynthetic parameters of leaves and chloroplasts.

    Science.gov (United States)

    Torres, Rocio; Diz, Virginia E; Lagorio, M Gabriela

    2018-04-18

    Effects of gold nanoparticles (average diameter: 10-14 nm) on leaves and chloroplasts have been studied. Gold nanoparticles (AuNPs) quenched significantly chlorophyll fluorescence when introduced both in intact leaves and isolated chloroplasts. Additionally, the fluorescence spectra corrected for light re-absorption processes showed a net decrease in the fluorescence ratio calculated as the quotient between the maximum fluorescence at 680 and 735 nm. This fact gave evidence for a reduction in the fluorescence emission of the PSII relative to that of the PSI. Strikingly, the photosynthetic parameters derived from the analysis of the slow phase of Kautsky's kinetics, the rate of oxygen evolution and the rate of photo-reduction of 2,6-dichlorophenolindophenol were increased in the presence of AuNPs indicating an apparent greater photosynthetic capacity. The observed results were consistent with an electron transfer process from the excited PSII, which was thermodynamically possible, and which competed with both the electron transport process that initiated photosynthesis and the deactivation of the excited PSII by fluorescence emission. Additionally, it is here explained, in terms of a completely rational kinetic scheme and their corresponding algebraic expressions, why the photosynthetic parameters and the variable and non-variable fluorescence of chlorophyll are modified in a photosynthetic tissue containing gold nanoparticles.

  15. Effects of silicon on photosynthetic characteristics of maize (Zea mays L.) on alluvial soil.

    Science.gov (United States)

    Xie, Zhiming; Song, Fengbin; Xu, Hongwen; Shao, Hongbo; Song, Ri

    2014-01-01

    The objectives of the study were to determine the effects of silicon on photosynthetic characteristics of maize on alluvial soil, including total chlorophyll contents, photosynthetic rate (P n), stomatal conductance (g s), transpiration rate (E), and intercellular CO2 concentration (C i ) using the method of field experiment, in which there were five levels (0, 45, 90, 150, and 225 kg · ha(-1)) of silicon supplying. The results showed that certain doses of silicon fertilizers can be used successfully in increasing the values of total chlorophyll contents, P n, and g s and decreasing the values of E and C i of maize leaves, which meant that photosynthetic efficiency of maize was significantly increased in different growth stages by proper doses of Si application on alluvial soil, and the optimal dose of Si application was 150 kg · ha(-1). Our results indicated that silicon in proper amounts can be beneficial in increasing the photosynthetic ability of maize, which would be helpful for the grain yield and growth of maize.

  16. Photosynthetic responses of C3 and C4 species to seasonal water variability and competition.

    Science.gov (United States)

    Niu, Shuli; Yuan, Zhiyou; Zhang, Yanfang; Liu, Weixing; Zhang, Lei; Huang, Jianhui; Wan, Shiqiang

    2005-11-01

    This study examined the impacts of seasonal water variability and interspecific competition on the photosynthetic characteristics of a C3 (Leymus chinensis) and a C4 (Chloris virgata) grass species. Plants received the same amount of water but in three seasonal patterns, i.e. the one-peak model (more water in the summer than in the spring and autumn), the two-peak model (more water in the spring and autumn than in the summer), and the average model (water evenly distributed over the growing season). The effects of water variability on the photosynthetic characteristics of the C3 and C4 species were dependent on season. There were significant differences in the photosynthetic characteristics of the C4 species in the summer and the C3 species in the autumn among the three water treatments. Interspecific competition exerted negative impacts on the C3 species in August and September but had no effects on the C4 species in any of the four measuring dates. The relative competitive capability of the two species was not altered by water availability. The assimilation rate, the maximum quantum yield of net CO2 assimilation, and the maximum rate of carboxylation of the C3 species were 13-56%, 5-11%, and 11-48% greater, respectively, in a monoculture than in a mixture in August and September. The results demonstrated that the photosynthetic characteristics of the C3 and C4 species were affected by water availability, but the effects varied considerably with season.

  17. Nitrate limitation and ocean acidification interact with UV-B to reduce photosynthetic performance in the diatom Phaeodactylum tricornutum

    Science.gov (United States)

    Li, W.; Gao, K.; Beardall, J.

    2015-04-01

    It has been proposed that ocean acidification (OA) will interact with other environmental factors to influence the overall impact of global change on biological systems. Accordingly we investigated the influence of nitrogen limitation and OA on the physiology of diatoms by growing the diatom Phaeodactylum tricornutum Bohlin under elevated (1000 μatm; high CO2 - HC) or ambient (390 μatm; low CO2 - LC) levels of CO2 with replete (110 μmol L-1; high nitrate - HN) or reduced (10 μmol L-1; low nitrate - LN) levels of NO3- and subjecting the cells to solar radiation with or without UV irradiance to determine their susceptibility to UV radiation (UVR, 280-400 nm). Our results indicate that OA and UVB induced significantly higher inhibition of both the photosynthetic rate and quantum yield under LN than under HN conditions. UVA or/and UVB increased the cells' non-photochemical quenching (NPQ) regardless of the CO2 levels. Under LN and OA conditions, activity of superoxide dismutase and catalase activities were enhanced, along with the highest sensitivity to UVB and the lowest ratio of repair to damage of PSII. HC-grown cells showed a faster recovery rate of yield under HN but not under LN conditions. We conclude therefore that nutrient limitation makes cells more prone to the deleterious effects of UV radiation and that HC conditions (ocean acidification) exacerbate this effect. The finding that nitrate limitation and ocean acidification interact with UV-B to reduce photosynthetic performance of the diatom P. tricornutum implies that ocean primary production and the marine biological C pump will be affected by OA under multiple stressors.

  18. Estimation of vegetation photosynthetic capacity from space-based measurements of chlorophyll fluorescence for terrestrial biosphere models.

    Science.gov (United States)

    Zhang, Yongguang; Guanter, Luis; Berry, Joseph A; Joiner, Joanna; van der Tol, Christiaan; Huete, Alfredo; Gitelson, Anatoly; Voigt, Maximilian; Köhler, Philipp

    2014-12-01

    Photosynthesis simulations by terrestrial biosphere models are usually based on the Farquhar's model, in which the maximum rate of carboxylation (Vcmax ) is a key control parameter of photosynthetic capacity. Even though Vcmax is known to vary substantially in space and time in response to environmental controls, it is typically parameterized in models with tabulated values associated to plant functional types. Remote sensing can be used to produce a spatially continuous and temporally resolved view on photosynthetic efficiency, but traditional vegetation observations based on spectral reflectance lack a direct link to plant photochemical processes. Alternatively, recent space-borne measurements of sun-induced chlorophyll fluorescence (SIF) can offer an observational constraint on photosynthesis simulations. Here, we show that top-of-canopy SIF measurements from space are sensitive to Vcmax at the ecosystem level, and present an approach to invert Vcmax from SIF data. We use the Soil-Canopy Observation of Photosynthesis and Energy (SCOPE) balance model to derive empirical relationships between seasonal Vcmax and SIF which are used to solve the inverse problem. We evaluate our Vcmax estimation method at six agricultural flux tower sites in the midwestern US using spaced-based SIF retrievals. Our Vcmax estimates agree well with literature values for corn and soybean plants (average values of 37 and 101 μmol m(-2)  s(-1) , respectively) and show plausible seasonal patterns. The effect of the updated seasonally varying Vcmax parameterization on simulated gross primary productivity (GPP) is tested by comparing to simulations with fixed Vcmax values. Validation against flux tower observations demonstrate that simulations of GPP and light use efficiency improve significantly when our time-resolved Vcmax estimates from SIF are used, with R(2) for GPP comparisons increasing from 0.85 to 0.93, and for light use efficiency from 0.44 to 0.83. Our results support the use of

  19. A rice plastidial nucleotide sugar epimerase is involved in galactolipid biosynthesis and improves photosynthetic efficiency.

    Directory of Open Access Journals (Sweden)

    Chunlai Li

    2011-07-01

    Full Text Available Photosynthesis is the final determinator for crop yield. To gain insight into genes controlling photosynthetic capacity, we selected from our large T-DNA mutant population a rice stunted growth mutant with decreased carbon assimilate and yield production named photoassimilate defective1 (phd1. Molecular and biochemical analyses revealed that PHD1 encodes a novel chloroplast-localized UDP-glucose epimerase (UGE, which is conserved in the plant kingdom. The chloroplast localization of PHD1 was confirmed by immunoblots, immunocytochemistry, and UGE activity in isolated chloroplasts, which was approximately 50% lower in the phd1-1 mutant than in the wild type. In addition, the amounts of UDP-glucose and UDP-galactose substrates in chloroplasts were significantly higher and lower, respectively, indicating that PHD1 was responsible for a major part of UGE activity in plastids. The relative amount of monogalactosyldiacylglycerol (MGDG, a major chloroplast membrane galactolipid, was decreased in the mutant, while the digalactosyldiacylglycerol (DGDG amount was not significantly altered, suggesting that PHD1 participates mainly in UDP-galactose supply for MGDG biosynthesis in chloroplasts. The phd1 mutant showed decreased chlorophyll content, photosynthetic activity, and altered chloroplast ultrastructure, suggesting that a correct amount of galactoglycerolipids and the ratio of glycolipids versus phospholipids are necessary for proper chloroplast function. Downregulated expression of starch biosynthesis genes and upregulated expression of sucrose cleavage genes might be a result of reduced photosynthetic activity and account for the decreased starch and sucrose levels seen in phd1 leaves. PHD1 overexpression increased photosynthetic efficiency, biomass, and grain production, suggesting that PHD1 plays an important role in supplying sufficient galactolipids to thylakoid membranes for proper chloroplast biogenesis and photosynthetic activity. These

  20. Diversity and abundance of photosynthetic sponges in temperate Western Australia

    Directory of Open Access Journals (Sweden)

    Brümmer Franz

    2009-02-01

    Full Text Available Abstract Background Photosynthetic sponges are important components of reef ecosystems around the world, but are poorly understood. It is often assumed that temperate regions have low diversity and abundance of photosynthetic sponges, but to date no studies have investigated this question. The aim of this study was to compare the percentages of photosynthetic sponges in temperate Western Australia (WA with previously published data on tropical regions, and to determine the abundance and diversity of these associations in a range of temperate environments. Results We sampled sponges on 5 m belt transects to determine the percentage of photosynthetic sponges and identified at least one representative of each group of symbionts using 16S rDNA sequencing together with microscopy techniques. Our results demonstrate that photosynthetic sponges are abundant in temperate WA, with an average of 63% of sponge individuals hosting high levels of photosynthetic symbionts and 11% with low to medium levels. These percentages of photosynthetic sponges are comparable to those found on tropical reefs and may have important implications for ecosystem function on temperate reefs in other areas of the world. A diverse range of symbionts sometimes occurred within a small geographic area, including the three "big" cyanobacterial clades, Oscillatoria spongeliae, "Candidatus Synechococcus spongiarum" and Synechocystis species, and it appears that these clades all occur in a wide range of sponges. Additionally, spongin-permeating red algae occurred in at least 7 sponge species. This study provides the first investigation of the molecular phylogeny of rhodophyte symbionts in sponges. Conclusion Photosynthetic sponges are abundant and diverse in temperate WA, with comparable percentages of photosynthetic to non-photosynthetic sponges to tropical zones. It appears that there are three common generalist clades of cyanobacterial symbionts of sponges which occur in a wide

  1. Enhanced Practical Photosynthetic CO2 Mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Gregory Kremer; David J. Bayless; Morgan Vis; Michael Prudich; Keith Cooksey; Jeff Muhs

    2006-01-15

    This final report highlights significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation Project during the period from 10/1/2001 through 01/02/2006. As indicated in the list of accomplishments below, our efforts during this project were focused on the selection of candidate organisms and growth surfaces and initiating long-term tests in the bench-scale and pilot-scale bioreactor test systems. Specific results and accomplishments for the program include: (1) CRF-2 test system: (a) Sampling test results have shown that the initial mass of algae loaded into the Carbon Recycling Facility Version 2 (CRF-2) system can be estimated with about 3% uncertainty using a statistical sampling procedure. (b) The pressure shim header pipe insert design was shown to have better flow for harvesting than the drilled-hole design. (c) The CRF-2 test system has undergone major improvements to produce the high flow rates needed for harvesting (as determined by previous experiments). The main changes to the system are new stainless steel header/frame units, with increased flow capacity and a modified pipe-end-sealing method to improve flow uniformity, and installation and plumbing for a new high flow harvesting pump. Qualitative system tests showed that the harvesting system performed wonderfully, cleaning the growth surfaces within a matter of seconds. (d) Qualitative tests have shown that organisms can be repopulated on a harvested section of a bioreactor screen, demonstrating that continuous bioreactor operation is feasible, with continuous cycles of harvesting and repopulating screens. (e) Final preparations are underway for quantitative, long-term tests in the CRF-2 with weekly harvesting. (2) Pilot-scale test system: (a) The construction of the pilot-scale bioreactor was completed, including the solar collector and light distribution system. Over the course of the project, the solar collector used in the light delivery system showed some degradation, but

  2. A Study on Photosynthetic Physiological Characteristics of Six Rare and Endangered Species

    Institute of Scientific and Technical Information of China (English)

    Tailin ZHONG; Guangwu ZHAO; Jiamiao CHU; Xiaomin GUO; Genyou LI

    2014-01-01

    The parameters of gas exchange and chlorophyl fluorescence in leaves of six rare and endangered species Neolitsea sericea, Cinnamomum japonicum var. cheni , Sinojackia microcarpa, Discocleidion glabrum var. trichocarpum, Parrotia sub-aequalis, Cercidiphyl um japonicum were measured in fields. The results showed that there were significant differences in photosynthetic capacity, intrinsic water use effi-ciency (WUEi ), the efficiency of primary conversion of light energy of PSⅡ and its potential activity, the quantum yield of PSⅡ electron transport, and the potential ca-pacity of heat dissipation among the six species. However, there was no significant difference in WUE. The highest values of net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (gs) occurred in D. glabrum var. trichocarpum and the lowest in S. microcarpa. On the contrary, D. glabrum var. trichocarpum had the lowest WUE, intrinsic water use efficiency (WUEi ) and S. microcarpa had the highest. The results indicated that D. glabrum var. trichocarpum had higher photo-synthetic capacity and poorer WUE, while S. microcarpa had lower photosynthetic capacity and greater WUE. Furthermore, the mean values of maximal fluorescence (Fm), potential efficiency of primary conversion of light energy of PSⅡ (Fv/Fm),ΦPSⅡ, actual efficiency of primary conversion of light energy of PSⅡ (F′v/F′m) and non-photochemical quenching coefficient (NPQ) were the highest in S. micro-carpa, indicating that its PSⅡ had higher capacity of heat dissipation and could prevent photosynthetic apparatus from damage by excessive light energy. Correlation analysis showed that there were significant correlations among photosynthetic physi-ological parameters. However, the initial fluorescence (Fo) was not significantly cor-related with any other parameters. This study also revealed the extremely significant positive correlations between Pn and Tr, gs, apparent quantum yield (AQY), be-tween Tr and

  3. Biotechnological Approaches to Enhance Halotolerance and Photosynthetic Efficacy in the Cyanobacterium, Fremyella diplosiphon

    Science.gov (United States)

    Tabatabai, Ben

    Growing concerns over dwindling energy supplies linked to nonrenewable fossil fuels have driven profound interest in biofuels as a clean and sustainable alternative. Cyanobacteria are a promising source of third-generation biofuel due to their fast generation time and high net biomass conversion. In this study, the effect of salinity stress on Fremyella diplosiphon, a model organism for studying photosynthetic pathways, was investigated and nanobiotechnological approaches undertaken to enhance its halotolerance and photosynthetic efficacy. Heat-induced mutagenesis resulted in a mutant strain that could survive in 20 g L-1 sodium chloride (NaCl) with no loss in pigmentation. To further enhance F. diplosiphon halotolerance, expression plasmids harboring the hlyB and mdh genes were overexpressed in the wild type resulting in two transformants that thrived in 35 g L-1 NaCl, the average salinity of sea water. In addition, no significant reduction in photosynthetic efficacy was detected in the halotolerant strains relative to the wild type. Total lipid content and fatty acid methyl ester composition of wild type and halotolerant strains were assessed for their potential as a production-scale biofuel agent. Methyl palmitate, the methyl ester of hexodeconoate (C16:0), was found to be most abundant in the wild type and transformants accounting for 60-70% of total FAMEs produced. Efforts to enhance the photosynthetic efficiency of the strains revealed that gold nanoparticle-derived surface plasmon resonance augmented culture growth and pigment accumulation. Cell-nanoparticles interactions were visualized using scanning and transmission electron microscopy. Our findings address two key challenges that cyanobacterial biofuel agents need to overcome: enhanced halotolerance and photosynthetic efficacy to minimize freshwater input and artificial light supply. These innovations have paved the way for an efficient cyanobacterial cultivation system for large-scale production of

  4. Photosynthetic capacity of 'Niagara Rosada' grapes grown under transparent plastic covering

    Directory of Open Access Journals (Sweden)

    Bruna Corrêa da Silva de Deus

    2016-06-01

    Full Text Available ABSTRACT: New techniques in tropical regions such as use of transparent plastic covering (TPC, have been employed in grapes to avoid the wetting leaves and fruits, which can reduce the occurrence of fungal diseases, reduce the use of sprays, and reduce damage caused by hail and high winds. TPC may significantly affect the photosynthetic rates of grapevines cultivated in tropical regions, and thus have strong effects on plant productivity and improve fruit quality. However, in the North of Rio de Janeiro region there are lacks of studies related to TPC effects on photosynthetic capacity. The objective of this study was to evaluate the photosynthetic capacity in 'Niagara Rosada' vines grown under TPC and without transparent plastic covering (WTPC. The experiment was conducted between April and June 2013, on Tabuinha farm, located in the 3rd district of São Fidélis, Rio de Janeiro State, Brazil. A completely randomized block design was used with two treatments (TPC and WTPC and twelve replications. Evaluations consisted of climatological variables, gas exchange and maximum quantum efficiency of open photosystem II centers-quantum yield (Fv/Fm It was possible to observe that under TPC maximum temperature increase of 2.3°C, relative humidity reduced 1.5%, vapor pressure deficit increase 0.4kPa, and light intensity reduced 47.7%. These changes did not cause photochemical damage to the leaves. The TPC promoted higher net photosynthetic rate at 800h, which was associated with higher stomatal conductance. Thus, the TPC used in the northern region of Rio de Janeiro State did not impair the photosynthetic capacity of 'Niagara Rosada' vines.

  5. Program GICC, final report (March 2005), inventory of carbonaceous aerosol particles from 1860 to 2100 or which carbonaceous aerosol for a significant climatic regional/global impact?

    International Nuclear Information System (INIS)

    Cachier, H.; Guinot, B.; Criqui, P.; Mima, S.; Brignon, J.M.; Penner, J.; Carmichael, G.; Gadi, R.; Denier Van der Gon, H.; Gregoire, J.M.; Liousse, C.; Michel, C.; Guillaume, B.; Junker, C.

    2007-01-01

    The aim of our program is to determine past, present and future emission inventories of carbonaceous particles from 1860 to 2100 for fossil fuel and biofuel sources. Emission inventories for savannah and forest fires have been developed by using burnt area products given by satellite for Asia and Africa. The strong collaboration with the different groups attending this GICC program has allowed to develop the following results. 1- With the improvement of algorithms and new choices for emission factors, emission inventories for black carbon (BC), primary organic carbon (OCp) and total organic carbon (OCtot) have been constructed for the period 1950 to 1997 for fossil fuel and biofuel sources. With these new development, biofuel sources have been seen to be significant, especially in the developing countries. 2- Past inventories have been developed for fossil fuel and biofuel sources from 1860 to 1997 by taking into account the evolution of fuel consumption, fuel use and emission factors. 3- Savannah and forest fire inventories have been constructed based on burnt area products, for Africa (1981-1991, 2000) and Asia (2000-2001). These results show the importance of using real time data instead of statistics. 4-Future emission inventory of black carbon by fossil fuel sources has been constructed for 2100 following the IPCC scenario A2 (catastrophic case) and B1 (perfect world). 5-Characterization of biofuel emissions has been realized by organizing an experiment in a combustion chamber where indian and chinese biofuels (fuelwood, agricultural wastes, dung-cake etc..). were burnt, reproducing the burning methods used in these countries. 6-Finally, the differences between the existing inventories of carbonaceous aerosols has been explained. (A.L.B.)

  6. Spring photosynthetic onset and net CO2 uptake in Alaska triggered by landscape thawing.

    Science.gov (United States)

    Parazoo, Nicholas C; Arneth, Almut; Pugh, Thomas A M; Smith, Ben; Steiner, Nicholas; Luus, Kristina; Commane, Roisin; Benmergui, Josh; Stofferahn, Eric; Liu, Junjie; Rödenbeck, Christian; Kawa, Randy; Euskirchen, Eugenie; Zona, Donatella; Arndt, Kyle; Oechel, Walt; Miller, Charles

    2018-04-24

    The springtime transition to regional-scale onset of photosynthesis and net ecosystem carbon uptake in boreal and tundra ecosystems are linked to the soil freeze-thaw state. We present evidence from diagnostic and inversion models constrained by satellite fluorescence and airborne CO 2 from 2012 to 2014 indicating the timing and magnitude of spring carbon uptake in Alaska correlates with landscape thaw and ecoregion. Landscape thaw in boreal forests typically occurs in late April (DOY 111 ± 7) with a 29 ± 6 day lag until photosynthetic onset. North Slope tundra thaws 3 weeks later (DOY 133 ± 5) but experiences only a 20 ± 5 day lag until photosynthetic onset. These time lag differences reflect efficient cold season adaptation in tundra shrub and the longer dehardening period for boreal evergreens. Despite the short transition from thaw to photosynthetic onset in tundra, synchrony of tundra respiration with snow melt and landscape thaw delays the transition from net carbon loss (at photosynthetic onset) to net uptake by 13 ± 7 days, thus reducing the tundra net carbon uptake period. Two global CO 2 inversions using a CASA-GFED model prior estimate earlier northern high latitude net carbon uptake compared to our regional inversion, which we attribute to (i) early photosynthetic-onset model prior bias, (ii) inverse method (scaling factor + optimization window), and (iii) sparsity of available Alaskan CO 2 observations. Another global inversion with zero prior estimates the same timing for net carbon uptake as the regional model but smaller seasonal amplitude. The analysis of Alaskan eddy covariance observations confirms regional scale findings for tundra, but indicates that photosynthesis and net carbon uptake occur up to 1 month earlier in evergreens than captured by models or CO 2 inversions, with better correlation to above-freezing air temperature than date of primary thaw. Further collection and analysis of boreal evergreen species over

  7. Improving Global Gross Primary Productivity Estimates by Computing Optimum Light Use Efficiencies Using Flux Tower Data

    Science.gov (United States)

    Madani, Nima; Kimball, John S.; Running, Steven W.

    2017-11-01

    In the light use efficiency (LUE) approach of estimating the gross primary productivity (GPP), plant productivity is linearly related to absorbed photosynthetically active radiation assuming that plants absorb and convert solar energy into biomass within a maximum LUE (LUEmax) rate, which is assumed to vary conservatively within a given biome type. However, it has been shown that photosynthetic efficiency can vary within biomes. In this study, we used 149 global CO2 flux towers to derive the optimum LUE (LUEopt) under prevailing climate conditions for each tower location, stratified according to model training and test sites. Unlike LUEmax, LUEopt varies according to heterogeneous landscape characteristics and species traits. The LUEopt data showed large spatial variability within and between biome types, so that a simple biome classification explained only 29% of LUEopt variability over 95 global tower training sites. The use of explanatory variables in a mixed effect regression model explained 62.2% of the spatial variability in tower LUEopt data. The resulting regression model was used for global extrapolation of the LUEopt data and GPP estimation. The GPP estimated using the new LUEopt map showed significant improvement relative to global tower data, including a 15% R2 increase and 34% root-mean-square error reduction relative to baseline GPP calculations derived from biome-specific LUEmax constants. The new global LUEopt map is expected to improve the performance of LUE-based GPP algorithms for better assessment and monitoring of global terrestrial productivity and carbon dynamics.

  8. Effect of Chernobyl radionuclides accumulation on the photosynthetic processes and nitrogen metabolism of Lupines Luteus L

    International Nuclear Information System (INIS)

    Zabolotnyj, A.I.; Goncharova, N.V.; Domash, V.I.; Sheverdov, V.V.; Akadehmiya Navuk Belarusi, Minsk

    1995-01-01

    The 134 Cs, 137 Cs and chlorophyll content activity of photochemical reaction in chloroplasts and symbiotic nitrogen fixation in root modules, activity of neutral protease, BAPAse and trypsin inhibitors were investigated for seeds to yellow lupine (Lupines luteus L). The level of radioactive contamination induced a tendency to change the activity of photosynthetic reaction and nitrogen fixation, significant changes in a set of trypsin inhibitors were found in nature lupine seeds

  9. A novel potassium channel in photosynthetic cyanobacteria.

    Directory of Open Access Journals (Sweden)

    Manuela Zanetti

    Full Text Available Elucidation of the structure-function relationship of a small number of prokaryotic ion channels characterized so far greatly contributed to our knowledge on basic mechanisms of ion conduction. We identified a new potassium channel (SynK in the genome of the cyanobacterium Synechocystis sp. PCC6803, a photosynthetic model organism. SynK, when expressed in a K(+-uptake-system deficient E. coli strain, was able to recover growth of these organisms. The protein functions as a potassium selective ion channel when expressed in Chinese hamster ovary cells. The location of SynK in cyanobacteria in both thylakoid and plasmamembranes was revealed by immunogold electron microscopy and Western blotting of isolated membrane fractions. SynK seems to be conserved during evolution, giving rise to a TPK (two-pore K(+ channel family member which is shown here to be located in the thylakoid membrane of Arabidopsis. Our work characterizes a novel cyanobacterial potassium channel and indicates the molecular nature of the first higher plant thylakoid cation channel, opening the way to functional studies.

  10. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    Energy Technology Data Exchange (ETDEWEB)

    Dr. David J. Bayless; Dr. Morgan Vis; Dr. Gregory Kremer; Dr. Michael Prudich; Dr. Keith Cooksey; Dr. Jeff Muhs

    2001-01-16

    This is the first quarterly report of the project Enhanced Practical Photosynthetic CO{sub 2} Mitigation. The official project start date, 10/02/2000, was delayed until 10/31/2000 due to an intellectual property dispute that was resolved. However, the delay forced a subsequent delay in subcontracting with Montana State University, which then delayed obtaining a sampling permit from Yellowstone National Park. However, even with these delays, the project moved forward with some success. Accomplishments for this quarter include: Culturing of thermophilic organisms from Yellowstone; Testing of mesophilic organisms in extreme CO{sub 2} conditions; Construction of a second test bed for additional testing; Purchase of a total carbon analyzer dedicated to the project; Construction of a lighting container for Oak Ridge National Laboratory optical fiber testing; Modified lighting of existing test box to provide more uniform distribution; Testing of growth surface adhesion and properties; Experimentation on water-jet harvesting techniques; and Literature review underway regarding uses of biomass after harvesting. Plans for next quarter's work and an update on the project's web page are included in the conclusions.

  11. CO2 elevation improves photosynthetic performance in progressive warming environment in white birch seedlings [v1; ref status: indexed, http://f1000r.es/up

    Directory of Open Access Journals (Sweden)

    Shouren Zhang

    2013-01-01

    Full Text Available White birch (Betula paperifera Mash seedlings were exposed to progressively warming in greenhouses under ambient and elevated CO2 concentrations for 5 months to explore boreal tree species’ potential capacity to acclimate to global climate warming and CO2 elevation. In situ foliar gas exchange, in vivo carboxylation characteristics and chlorophyll fluorescence were measured at temperatures of 26oC and 37oC. Elevated CO2 significantly increased net photosynthetic rate (Pn at both measurement temperatures, and Pn at 37oC was higher than that at 26oC under elevated CO2. Stomatal conductance (gs was lower at 37oC than at 26oC, while transpiration rate (E was higher at 37oC than that at 26oC. Elevated CO2 significantly increased instantaneous water-use efficiency (WUE at both 26oC and 37oC, but WUE was markedly enhanced at 37oC under elevated CO2. The effect of temperature on maximal carboxylation rate (Vcmax, PAR-saturated electron transport rate (Jmax and triose phosphate utilization (TPU varied with CO2, and the Vcmax and Jmax were significantly higher at 37oC than at 26oC under elevated CO2. However, there were no significant interactive effects of CO2 and temperature on TPU. The actual photochemical efficiency of PSII (DF/ Fm’, total photosynthetic linear electron transport rate through PSII (JT and the partitioning of JT to carboxylation (Jc were higher at 37oC than at 26oC under elevated CO2. Elevated CO2 significantly suppressed the partitioning of JT to oxygenation (Jo/JT. The data suggest that the CO2 elevation and progressive warming greatly enhanced photosynthesis in white birch seedlings in an interactive fashion.

  12. Photosynthetic efficiency of Chlamydomonas reinhardtii in flashing light

    NARCIS (Netherlands)

    Vejrazka, C.; Janssen, M.G.J.; Streefland, M.; Wijffels, R.H.

    2011-01-01

    Efficient light to biomass conversion in photobioreactors is crucial for economically feasible microalgae production processes. It has been suggested that photosynthesis is enhanced in short light path photobioreactors by mixing-induced flashing light regimes. In this study, photosynthetic

  13. Effects of 1-butanol, neomycin and calcium on the photosynthetic ...

    African Journals Online (AJOL)

    ajl yemi

    2011-10-31

    Oct 31, 2011 ... (Shanghai Jierui Bio-Engineering Co., Ltd.) were used in the total. RNA extraction of ..... PC and reverse through calcium removal agent. EGTA indicating .... Photosynthetic characteristics and tolerance to photo- oxidation of ...

  14. Photosynthetic responses of pea plants (Pisum sativum L. cv. Little ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-08-04

    Aug 4, 2008 ... (O3) have fundamental effects on CO2 exchange by plants. ... produce responses such as reduced photosynthetic rates and earlier senescence .... quality localities treatments and two soil regimes in Riyadh city, KSA. Pn rates.

  15. Photosynthetic and nitrogen fixation capability in several soybean mutant lines

    International Nuclear Information System (INIS)

    Gandanegara, S.; Hendratno, K.

    1987-01-01

    Photosynthetic and nitrogen fixation capability in several soybean mutant lines. A greenhouse experiment has been carried out to study photosynthetic and nitrogen fixation capability of five mutant lines and two soybean varieties. An amount of 330 uCi of 14 CO 2 was fed to the plants including of the non-fixing reference crop (Chippewa non-nodulating isoline). Nitrogen fixation measurements was carried out using 15 N isotope dilution technique according to A-value concept. Results showed that beside variety/mutant lines, plant growth also has important role in photosynthetic and N fixing capability. Better growth and a higher photosynthetic capability in Orba, mutant lines nos. 63 and 65 resulted in a greater amount of N 2 fixed (mg N/plant) than other mutant lines. (author). 12 refs.; 5 figs

  16. Counting viruses and bacteria in photosynthetic microbial mats

    NARCIS (Netherlands)

    Carreira, C; Staal, M.; Middelboe, M.; Brussaard, C.P.D.

    2015-01-01

    Viral abundances in benthic environments are the highest found in aquatic systems. Photosynthetic microbial mats represent benthic environments with high microbial activity and possibly high viral densities, yet viral abundances have not been examined in such systems. Existing extraction procedures

  17. Effect of space mutation on photosynthetic characteristics of soybean varieties

    International Nuclear Information System (INIS)

    Liu Xinlei; Ma Yansong; Luan Xiaoyan; Man Weiqun; Xu Dechun; Meng Lifen; Fu Lixin; Zhao Xiaonan; Liu Qi

    2011-01-01

    In order to elucidate the response of the photosynthetic traits of soybean to space mutation, three soybean varieties (lines) of Heinong 48, Heinong 44 and Ha 2291-Y were carried by artificial satellite in 2006 and the net photosynthetic rate (Pn), stomatal conductance (Cond), intercellular CO 2 concentration (Ci) and stomatal resistance (Rs) from SP 1 to SP 4 generation were determined. The results showed that space mutation affected photosynthesis traits of soybean. The photosynthetic rate of soybean varieties by space mutation occurred different levels of genetic variation and the positive mutation rate were higher. Coefficient of variation among generations were SP 2 > SP 3 > SP 4 > CK. Results suggest that space mutation can effectively create soybean materials with higher photosynthetic rate. (authors)

  18. Carotenoids are essential for the assembly of cyanobacterial photosynthetic complexes

    NARCIS (Netherlands)

    Tóth, T.N.; Chukhutsina, Volha; Domonkos, Ildikó; Knoppová, Jana; Komenda, Josef; Kis, Mihály; Lénárt, Zsófia; Garab, Gyozo; Kovács, László; Gombos, Zoltán; Amerongen, Van Herbert

    2015-01-01

    In photosynthetic organisms, carotenoids (carotenes and xanthophylls) are important for light harvesting, photoprotection and structural stability of a variety of pigment-protein complexes. Here, we investigated the consequences of altered carotenoid composition for the functional organization of

  19. Variability of photosynthetic pigments in the Colombian Pacific ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Picture series of surface chlorophyll,. SST, wind ... photosynthetic pigments during the time of inten- sification of ... calculation of Ekman pumping (We) using finite- differencing to ..... Legeckis R 1986 A satellite time series sea surface tempera-.

  20. Global industry with regional significance. Social perspectives

    International Nuclear Information System (INIS)

    2005-05-01

    As the world's third largest exporter of oil, Norway is an energy superpower in an international context. 2004 was a record-breaking year on the Norwegian Shelf. Never before did production reach such heights. The oil and gas industry is Norway's largest and most important industry. It is responsible for one-third of the State's revenues, and nearly half of Norway's total export revenues. The report provides an overview of the Norwegian Shelf today, and facts about Norway concerning the economy and standard of living. The industry's role in regional business development is also analysed, as well as expertise and technological development. Aspects on the environment and co-existence at sea are reviewed, with information on emissions to air and discharges to sea. Environmental considerations and technological challenges are briefly reported. The petroleum industry has set the standard within Health, Safety and the Environment (HSE). The work has been based on close cooperation between the authorities and the operating companies, their organizations and the employee organizations on the Shelf. Details on these activities are reported. Finally, responsibility for the community and issues concerning corporate social responsibility are mentioned (ml)

  1. On the photosynthetic potential in the very Early Archean oceans.

    Science.gov (United States)

    Avila, Daile; Cardenas, Rolando; Martin, Osmel

    2013-02-01

    In this work we apply a mathematical model of photosynthesis to quantify the potential for photosynthetic life in the very Early Archean oceans. We assume the presence of oceanic blockers of ultraviolet radiation, specifically ferrous ions. For this scenario, our results suggest a potential for photosynthetic life greater than or similar to that in later eras/eons, such as the Late Archean and the current Phanerozoic eon.

  2. Ultrafast fluorescence of photosynthetic crystals and light-harvesting complexes

    OpenAIRE

    Oort, van, B.F.

    2008-01-01

    This thesis focuses on the study of photosynthetic pigment protein complexes using time resolved fluorescence techniques. Fluorescence spectroscopy often requires attaching fluorescent labels to the proteins under investigation. With photosynthetic proteins this is not necessary, because these proteins contain fluorescent pigments. Each pigment’s fluorescence is influenced by its environment, and thereby may provide information on structure and dynamics of pigment protein complexes in vitro a...

  3. Production of bioplastics and hydrogen gas by photosynthetic microorganisms

    Science.gov (United States)

    Yasuo, Asada; Masato, Miyake; Jun, Miyake

    1998-03-01

    Our efforts have been aimed at the technological basis of photosynthetic-microbial production of materials and an energy carrier. We report here accumulation of poly-(3-hydroxybutyrate) (PHB), a raw material of biodegradable plastics and for production of hydrogen gas, and a renewable energy carrier by photosynthetic microorganisms (tentatively defined as cyanobacteria plus photosynthetic bateria, in this report). A thermophilic cyanobacterium, Synechococcus sp. MA19 that accumulates PHB at more than 20% of cell dry wt under nitrogen-starved conditions was isolated and microbiologically identified. The mechanism of PHB accumulation was studied. A mesophilic Synechococcus PCC7942 was transformed with the genes encoding PHB-synthesizing enzymes from Alcaligenes eutrophus. The transformant accumulated PHB under nitrogen-starved conditions. The optimal conditions for PHB accumulation by a photosynthetic bacterium grown on acetate were studied. Hydrogen production by photosynthetic microorganisms was studied. Cyanobacteria can produce hydrogen gas by nitrogenase or hydrogenase. Hydrogen production mediated by native hydrogenase in cyanobacteria was revealed to be in the dark anaerobic degradation of intracellular glycogen. A new system for light-dependent hydrogen production was targeted. In vitro and in vivo coupling of cyanobacterial ferredoxin with a heterologous hydrogenase was shown to produce hydrogen under light conditions. A trial for genetic trasformation of Synechococcus PCC7942 with the hydrogenase gene from Clostridium pasteurianum is going on. The strong hydrogen producers among photosynthetic bacteria were isolated and characterized. Co-culture of Rhodobacter and Clostriumdium was applied to produce hydrogen from glucose. Conversely in the case of cyanobacteria, genetic regulation of photosynthetic proteins was intended to improve conversion efficiency in hydrogen production by the photosynthetic bacterium, Rhodobacter sphaeroides RV. A mutant acquired by

  4. Elucidating the composition and conservation of the autophagy pathway in photosynthetic eukaryotes

    Science.gov (United States)

    Shemi, Adva; Ben-Dor, Shifra; Vardi, Assaf

    2015-01-01

    Aquatic photosynthetic eukaryotes represent highly diverse groups (green, red, and chromalveolate algae) derived from multiple endosymbiosis events, covering a wide spectrum of the tree of life. They are responsible for about 50% of the global photosynthesis and serve as the foundation for oceanic and fresh water food webs. Although the ecophysiology and molecular ecology of some algal species are extensively studied, some basic aspects of algal cell biology are still underexplored. The recent wealth of genomic resources from algae has opened new frontiers to decipher the role of cell signaling pathways and their function in an ecological and biotechnological context. Here, we took a bioinformatic approach to explore the distribution and conservation of TOR and autophagy-related (ATG) proteins (Atg in yeast) in diverse algal groups. Our genomic analysis demonstrates conservation of TOR and ATG proteins in green algae. In contrast, in all 5 available red algal genomes, we could not detect the sequences that encode for any of the 17 core ATG proteins examined, albeit TOR and its interacting proteins are conserved. This intriguing data suggests that the autophagy pathway is not conserved in red algae as it is in the entire eukaryote domain. In contrast, chromalveolates, despite being derived from the red-plastid lineage, retain and express ATG genes, which raises a fundamental question regarding the acquisition of ATG genes during algal evolution. Among chromalveolates, Emiliania huxleyi (Haptophyta), a bloom-forming coccolithophore, possesses the most complete set of ATG genes, and may serve as a model organism to study autophagy in marine protists with great ecological significance. PMID:25915714

  5. Removal of Anabaena spiroides by potassium permanganate pre-oxidation: effect on photosynthetic capacity and molecular weight distribution.

    Science.gov (United States)

    Qiao, Junlian; Zhang, Xiaodong; Lv, Liping

    2017-11-01

    Bench scale tests were conducted to investigate the effect of potassium permanganate pre-oxidation on the photosynthetic activity and molecular weight distribution of Anabaena spiroides. Different concentrations of potassium permanganate were added into the suspension of Anabaena spiroides, one of the dominant algae in water bloom, and after pre-oxidation of permanganate for 1 h, the results show that the removal rate significantly increases by 33.99~36.35% compared to direct coagulation. Then, the algal characteristics, including photosynthetic ability, the changes in extracellular organic matter three-dimensional fluorescence, and the distribution of molecular weight were conducted and the results show that along with increasing concentration of potassium permanganate, the photosynthetic ability of algae decreases, more extracellular organic matter is secreted, and large molecular weight matter (humic-like and fulvic-like substances) are generated. Therefore, this study demonstrates that potassium permanganate could be used in addressing the algae-rich water.

  6. High rates of solar radiation - an important natural stress factor of the photosynthetic activity of mountainous norway spruce stands

    International Nuclear Information System (INIS)

    Sprtova, M.; Marek, M.V.

    1996-01-01

    Photosynthetic activity can be regarded as the basis of biomass productivity and vitality of forest trees, respectively. Moreover, this activity is under the strong influence of environment. Excess of photosynthetically active radiation (PhAR) can be a harmful factor of environment which is the reason of photoinhibition. Photoinhibition is demonstrated by a decrease of photosynthetic rate. An analysis of the influence of PhAR excess on function of the assimilatory apparatus of Norway spruce during summer days was done. The strong influence of PhAR excess on values of parameters of photosynthesis reflecting changes in the level of quanta capture and electron transport chain was observed. The comprehensive description of the method of chlorophyll a is given. Excess of PhAR caused rapid changes of assimilatory apparatus function and thus this PhAR excess can be regarded as a significant stress of productional activity of Norway spruce stands under field conditions

  7. Leaf Characteristics and Photosynthetic Performance of Floating, Emergent and Terrestrial Leaves of Marsilea quadrifolia

    Directory of Open Access Journals (Sweden)

    Chia-Hong Lin

    2007-09-01

    Full Text Available Individuals of Marsilea quadrifolia, an amphibious fern, experiencing extreme variation in environment develop heterophyll. In this study, we compared stomatal and trichome density on upper and lower surfaces, leaf and petiole area mass ratio, spectral properties and photosynthetic performance of floating, emergent and terrestrial leaves of M. quadrifolia, to explore the ecological advantages of producing different leaf types. Morphological measurement reveals that these three types of leaf display highly differences in stomatal density on lower epidermis, trichome density on both surfaces and petiole dry mass per length, and reflectance coefficient between 500 and 650 nm. In contrast, no significant difference was found in the PSII electron transport rate of the three types of leaves. The analysis of stable carbon isotope ratio of the three types of leaves indicates that they all use C3 photosynthetic pathway.

  8. Dynamic optimization of CELSS crop photosynthetic rate by computer-assisted feedback control

    Science.gov (United States)

    Chun, C.; Mitchell, C. A.

    1997-01-01

    A procedure for dynamic optimization of net photosynthetic rate (Pn) for crop production in Controlled Ecological Life-Support Systems (CELSS) was developed using leaf lettuce as a model crop. Canopy Pn was measured in real time and fed back for environmental control. Setpoints of photosynthetic photon flux (PPF) and CO_2 concentration for each hour of the crop-growth cycle were decided by computer to reach a targeted Pn each day. Decision making was based on empirical mathematical models combined with rule sets developed from recent experimental data. Comparisons showed that dynamic control resulted in better yield per unit energy input to the growth system than did static control. With comparable productivity parameters and potential for significant energy savings, dynamic control strategies will contribute greatly to the sustainability of space-deployed CELSS.

  9. Effects of water stress and high temperature on photosynthetic rates of two species of Prosopis.

    Science.gov (United States)

    Delatorre, Jose; Pinto, Manuel; Cardemil, Liliana

    2008-08-21

    The main aim of this research was to compare the photosynthetic responses of two species of Prosopis, Prosopis chilensis (algarrobo) and Prosopis tamarugo (tamarugo) subjected to heat and water stress, to determine how heat shock or water deficit, either individually or combined, affect the photosynthesis of these two species. The photosynthetic rates expressed as a function of photon flow density (PFD) were determined by the O(2) liberated, in seedlings of tamarugo and algarrobo subjected to two water potentials: -0.3 MPa and -2.5 MPa and to three temperatures: 25 degrees C, 35 degrees C and 40 degrees C. Light response curves were constructed to obtain light compensation and light saturation points, maximum photosynthetic rates, quantum yields and dark respiration rates. The photochemical efficiency as the F(v)/F(m) ratio and the amount of RUBISCO were also determined under heat shock, water deficit, and under the combined action of both stress. Photosynthetic rates at a light intensity higher than 500 micromole photons m(-2)s(-1) were not significantly different (P>0.05) between species when measured at 25 degrees C under the same water potential. The maximum photosynthetic rates decreased with temperature in both species and with water deficit in algarrobo. At 40 degrees C and -2.5 MPa, the photosynthetic rate of algarrobo fell to 72% of that of tamarugo. The quantum yield decreased in algarrobo with temperature and water deficit and it was reduced by 50% when the conditions were 40 degrees C and -2.5 MPa. Dark respiration increased by 62% respect to the control at 40 degrees C in tamarugo while remained unchanged in algarrobo. The photochemical efficiency decreased with both, high temperature and water deficit, without differences between species. RUBISCO content increased in algarrobo 35 degrees C. Water deficit reduced the amount of RUBISCO in both species. The results of this work support the conclusion that in both Prosopis species, the interaction between

  10. Hybrid artificial photosynthetic systems comprising semiconductors as light harvesters and biomimetic complexes as molecular cocatalysts.

    Science.gov (United States)

    Wen, Fuyu; Li, Can

    2013-11-19

    Solar fuel production through artificial photosynthesis may be a key to generating abundant and clean energy, thus addressing the high energy needs of the world's expanding population. As the crucial components of photosynthesis, the artificial photosynthetic system should be composed of a light harvester (e.g., semiconductor or molecular dye), a reduction cocatalyst (e.g., hydrogenase mimic, noble metal), and an oxidation cocatalyst (e.g., photosystem II mimic for oxygen evolution from water oxidation). Solar fuel production catalyzed by an artificial photosynthetic system starts from the absorption of sunlight by the light harvester, where charge separation takes place, followed by a charge transfer to the reduction and oxidation cocatalysts, where redox reaction processes occur. One of the most challenging problems is to develop an artificial photosynthetic solar fuel production system that is both highly efficient and stable. The assembly of cocatalysts on the semiconductor (light harvester) not only can facilitate the charge separation, but also can lower the activation energy or overpotential for the reactions. An efficient light harvester loaded with suitable reduction and oxidation cocatalysts is the key for high efficiency of artificial photosynthetic systems. In this Account, we describe our strategy of hybrid photocatalysts using semiconductors as light harvesters with biomimetic complexes as molecular cocatalysts to construct efficient and stable artificial photosynthetic systems. We chose semiconductor nanoparticles as light harvesters because of their broad spectral absorption and relatively robust properties compared with a natural photosynthesis system. Using biomimetic complexes as cocatalysts can significantly facilitate charge separation via fast charge transfer from the semiconductor to the molecular cocatalysts and also catalyze the chemical reactions of solar fuel production. The hybrid photocatalysts supply us with a platform to study the

  11. Multilayer models of photosynthetic membranes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Brocklehurst, J R; Flanagan, M T

    1982-01-01

    The primary aim of this project has been to build an artificial membrane in which is incorporated, in a functional state, the protein bacteriorhodopsin responsible for generating an electrical potential difference across the membrane of the photosynthetic bacterium, halobacterium halobium, and to investigate the use of this artificial system as the basis of a solar cell. the bacteriorhodopsin has been incorporated into Langmuir-Blodgett multilayers. If ths supporting filter is then illuminated, a potential difference is generated between the two compartments. The lipid in the filter appears to act as a charge carrier for protons, the charge species that forms the electrochemical gradient generated by the bacteriorhodopsin when this molecule absorbs light. The internal resistances of such solar cells were determined and found to be so high that the cells could not be seriously considered as competitors with classical semiconductor cells. Multilayerswere deposited onto filters in which ion carriers that make the filters permeable to sodium ions had been dissolved in the paraffin. The photovoltage obtained indicated that protons transferred from one side of the filter to the other by the action of the bacteriorhodopsin were bing exchanged for sodium ions. A secondary aim of the project has been to examine the possibility of depositing mixed multilayers of a dye and a long chain quinone onto a semiconductor surface. A sensitizing multilayer has been prepared and the mobility of long chain quinones within the layers is high enough to warrant further research. However, it was found that, with the dyes and quinones used, quenched complexes were formed which would not act as sensitizers.

  12. Anaerobic energy metabolism in unicellular photosynthetic eukaryotes.

    Science.gov (United States)

    Atteia, Ariane; van Lis, Robert; Tielens, Aloysius G M; Martin, William F

    2013-02-01

    Anaerobic metabolic pathways allow unicellular organisms to tolerate or colonize anoxic environments. Over the past ten years, genome sequencing projects have brought a new light on the extent of anaerobic metabolism in eukaryotes. A surprising development has been that free-living unicellular algae capable of photoautotrophic lifestyle are, in terms of their enzymatic repertoire, among the best equipped eukaryotes known when it comes to anaerobic energy metabolism. Some of these algae are marine organisms, common in the oceans, others are more typically soil inhabitants. All these species are important from the ecological (O(2)/CO(2) budget), biotechnological, and evolutionary perspectives. In the unicellular algae surveyed here, mixed-acid type fermentations are widespread while anaerobic respiration, which is more typical of eukaryotic heterotrophs, appears to be rare. The presence of a core anaerobic metabolism among the algae provides insights into its evolutionary origin, which traces to the eukaryote common ancestor. The predicted fermentative enzymes often exhibit an amino acid extension at the N-terminus, suggesting that these proteins might be compartmentalized in the cell, likely in the chloroplast or the mitochondrion. The green algae Chlamydomonas reinhardtii and Chlorella NC64 have the most extended set of fermentative enzymes reported so far. Among the eukaryotes with secondary plastids, the diatom Thalassiosira pseudonana has the most pronounced anaerobic capabilities as yet. From the standpoints of genomic, transcriptomic, and biochemical studies, anaerobic energy metabolism in C. reinhardtii remains the best characterized among photosynthetic protists. This article is part of a Special Issue entitled: The evolutionary aspects of bioenergetic systems. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Evolution and metabolic significance of the urea cycle in photosynthetic diatoms

    Czech Academy of Sciences Publication Activity Database

    Allen, A. E.; Dupont, Ch. L.; Oborník, Miroslav; Horák, Aleš; Nunes-Nesi, A.; McCrow, J. P.; Zheng, H.; Johnson, D. A.; Hu, H.; Fernie, A. R.; Bowler, Ch.

    2011-01-01

    Roč. 473, č. 7346 (2011), s. 203-209 ISSN 0028-0836 R&D Projects: GA ČR GA206/08/1423 Institutional research plan: CEZ:AV0Z60220518 Keywords : CARBAMOYL-PHOSPHATE SYNTHETASE * PHAEODACTYLUM-TRICORNUTUM * MAXIMUM-LIKELIHOOD * PHYLOGENETIC RECONSTRUCTION * MOLECULAR EVOLUTION * SEQUENCE ALIGNMENT * DIVERGENCE TIMES * MARINE DIATOMS * MIXED MODELS * TREE Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 36.280, year: 2011

  14. Canopy profiles of photosynthetic parameters under elevated CO2 and N fertilization in a poplar plantation

    International Nuclear Information System (INIS)

    Calfapietra, Carlo; Tulva, Ingmar; Eensalu, Eve; Perez, Marta; De Angelis, Paolo; Scarascia-Mugnozza, Giuseppe; Kull, Olevi

    2005-01-01

    A poplar plantation has been exposed to an elevated CO 2 concentration for 5 years using the free air CO 2 enrichment (FACE) technique. Even after such a long period of exposure, leaves of Populus x euramericana have not shown clear signs of photosynthetic acclimation. Only at the end of the growing season for shade leaves was a decrease of maximum velocity of carboxylation (V cmax ) observed. Maximum electron transport rate (J max ) was increased by FACE treatment in July. Assimilation rates at CO 2 partial pressure of 400 (A 400 ) and 600 (A 600 ) μmol mol -1 were not significantly different under FACE treatment. Most notably FACE significantly decreased stomatal conductance (g s ) both on upper and lower canopy leaves. N fertilization increased N content in the leaves on mass basis (N m ) and specific leaf area (SLA) in both CO 2 treatments but did not influence the photosynthetic parameters. These data show that in poplar plantations the long-term effects of elevated CO 2 on photosynthesis do not differ considerably from the short-term ones even with N deposition. - Photosynthetic acclimation occurred only marginally

  15. Endosulfan induced changes in growth rate, pigment composition and photosynthetic activity of mosquito fern Azolla microphylla

    Directory of Open Access Journals (Sweden)

    Raja W.

    2012-11-01

    Full Text Available This paper is the first in a series reporting a study on the effects of different concentrations of insecticide, Endosulfan (0-600ppm was premeditated on 5th day after insecticide exposure with respect to growth rate, pigment composition and photosynthetic activity of Azolla microphylla under laboratory conditions which become non-target organism in the rice fields. Endosulfan inhibited the relative growth rate, pigment content and photosynthetic O2 evolution. Phycocyanin was main target followed by carotenoid and total chlorophyll. Significant increase in pigment, flavonoid and Anthocyanin was noticed after six days of treatment. In contrast to the photosynthetic activity, the rate of respiration in Azolla microphylla was increased significantly. Our results show that Endosulfan at normally recommended field rates and intervals are seldom deleterious to the beneficial and Eco friendly Azolla microphylla and their activities and thus in turn suppress plant growth and development. Phytotoxity of Azolla microphylla can be minimized by restrictions on application, timing, method and rate of application.

  16. Plastid genome structure and loss of photosynthetic ability in the parasitic genus Cuscuta.

    Science.gov (United States)

    Revill, Meredith J W; Stanley, Susan; Hibberd, Julian M

    2005-09-01

    The genus Cuscuta (dodder) is composed of parasitic plants, some species of which appear to be losing the ability to photosynthesize. A molecular phylogeny was constructed using 15 species of Cuscuta in order to assess whether changes in photosynthetic ability and alterations in structure of the plastid genome relate to phylogenetic position within the genus. The molecular phylogeny provides evidence for four major clades within Cuscuta. Although DNA blot analysis showed that Cuscuta species have smaller plastid genomes than tobacco, and that plastome size varied significantly even within one Cuscuta clade, dot blot analysis indicated that the dodders possess homologous sequence to 101 genes from the tobacco plastome. Evidence is provided for significant rates of DNA transfer from plastid to nucleus in Cuscuta. Size and structure of Cuscuta plastid genomes, as well as photosynthetic ability, appear to vary independently of position within the phylogeny, thus supporting the hypothesis that within Cuscuta photosynthetic ability and organization of the plastid genome are changing in an unco-ordinated manner.

  17. Seasonal variability of foliar photosynthetic and morphological traits and drought impacts in a Mediterranean mixed forest.

    Science.gov (United States)

    Sperlich, D; Chang, C T; Peñuelas, J; Gracia, C; Sabaté, S

    2015-05-01

    The Mediterranean region is a hot spot of climate change vulnerable to increased droughts and heat waves. Scaling carbon fluxes from leaf to landscape levels is particularly challenging under drought conditions. We aimed to improve the mechanistic understanding of the seasonal acclimation of photosynthesis and morphology in sunlit and shaded leaves of four Mediterranean trees (Quercus ilex L., Pinus halepensis Mill., Arbutus unedo L. and Quercus pubescens Willd.) under natural conditions. Vc,max and Jmax were not constant, and mesophyll conductance was not infinite, as assumed in most terrestrial biosphere models, but varied significantly between seasons, tree species and leaf position. Favourable conditions in winter led to photosynthetic recovery and growth in the evergreens. Under moderate drought, adjustments in the photo/biochemistry and stomatal/mesophyllic diffusion behaviour effectively protected the photosynthetic machineries. Severe drought, however, induced early leaf senescence mostly in A. unedo and Q. pubescens, and significantly increased leaf mass per area in Q. ilex and P. halepensis. Shaded leaves had lower photosynthetic potentials but cushioned negative effects during stress periods. Species-specificity, seasonal variations and leaf position are key factors to explain vegetation responses to abiotic stress and hold great potential to reduce uncertainties in terrestrial biosphere models especially under drought conditions. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. A new empirical model to estimate hourly diffuse photosynthetic photon flux density

    Science.gov (United States)

    Foyo-Moreno, I.; Alados, I.; Alados-Arboledas, L.

    2018-05-01

    Knowledge of the photosynthetic photon flux density (Qp) is critical in different applications dealing with climate change, plant physiology, biomass production, and natural illumination in greenhouses. This is particularly true regarding its diffuse component (Qpd), which can enhance canopy light-use efficiency and thereby boost carbon uptake. Therefore, diffuse photosynthetic photon flux density is a key driving factor of ecosystem-productivity models. In this work, we propose a model to estimate this component, using a previous model to calculate Qp and furthermore divide it into its components. We have used measurements in urban Granada (southern Spain), of global solar radiation (Rs) to study relationships between the ratio Qpd/Rs with different parameters accounting for solar position, water-vapour absorption and sky conditions. The model performance has been validated with experimental measurements from sites having varied climatic conditions. The model provides acceptable results, with the mean bias error and root mean square error varying between - 0.3 and - 8.8% and between 9.6 and 20.4%, respectively. Direct measurements of this flux are very scarce so that modelling simulations are needed, this is particularly true regarding its diffuse component. We propose a new parameterization to estimate this component using only measured data of solar global irradiance, which facilitates its use for the construction of long-term data series of PAR in regions where continuous measurements of PAR are not yet performed.

  19. Growth and Accumulation of Secondary Metabolites in Perilla as Affected by Photosynthetic Photon Flux Density and Electrical Conductivity of the Nutrient Solution

    Directory of Open Access Journals (Sweden)

    Na Lu

    2017-05-01

    Full Text Available The global demand for medicinal plants is increasing. The quality of plants grown outdoors, however, is difficult to control. Myriad environmental factors influence plant growth and directly impact biosynthetic pathways, thus affecting the secondary metabolism of bioactive compounds. Plant factories use artificial lighting to increase the quality of medicinal plants and stabilize production. Photosynthetic photon flux density (PPFD and electrical conductivity (EC of nutrient solutions are two important factors that substantially influence perilla (Perilla frutescens, Labiatae plant growth and quality. To identify suitable levels of PPFD and EC for perilla plants grown in a plant factory, the growth, photosynthesis, and accumulation of secondary metabolites in red and green perilla plants were measured at PPFD values of 100, 200, and 300 μmol m-2 s-1 in nutrient solutions with EC values of 1.0, 2.0, and 3.0 dS m-1. The results showed significant interactive effects between PPFD and EC for both the fresh and dry weights of green perilla, but not for red perilla. The fresh and dry weights of shoots and leafy areas were affected more by EC than by PPFD in green perilla, whereas they were affected more by PPFD than by EC in red perilla. Leaf net photosynthetic rates were increased as PPFD increased in both perilla varieties, regardless of EC. The perillaldehyde concentration (mg g-1 in red perilla was unaffected by the treatments, but accumulation in plants (mg per plant was significantly enhanced as the weight of dry leaves increased. Perillaldehyde concentrations in green perilla showed significant differences between combinations of the highest PPFD with the highest EC and the lowest PPFD with the lowest EC. Rosmarinic acid concentration (mg g-1 was increased in a combination of low EC and high PPFD conditions. Optimal cultivation conditions of red and green perilla in plant factory will be discussed in terms of plant growth and contents of

  20. Physiological and photosynthetic response of quinoa to drought stress

    Directory of Open Access Journals (Sweden)

    Rachid Fghire

    2015-06-01

    Full Text Available Water shortage is a critical problem touching plant growth and yield in semi-arid areas, for instance the Mediterranean región. For this reason was studied the physiological basis of drought tolerance of a new, drought tolerant crop quinoa (Chenopodium quinoa Willd. tested in Morocco in two successive seasons, subject to four irrigation treatments (100, 50, and 33%ETc, and rainfed. The chlorophyll a fluorescence transients were analyzed by the JIP-test to transíate stress-induced damage in these transients to changes in biophysical parameter's allowing quantification of the energy flow through the photosynthetic apparatus. Drought stress induced a significant decrease in the maximum quantum yield of primary photochemistry (Φpo = Fv/Fm, and the quantum yield of electron transport (Φeo. The amount of active Photosystem II (PSII reaction centers (RC per excited cross section (RC/CS also decreased when exposed to the highest drought stress. The effective antenna size of active RCs (ABS/RC increased and the effective dissipation per active reaction centers (DIo/RC increased by increasing drought stress during the growth season in comparison to the control. However the performance index (PI, was a very sensitive indicator of the physiological status of plants. Leaf area index, leaf water potential and stomatal conductance decreased as the drought increased. These results indicate that, in quinoa leaf, JIP-test can be used as a sensitive method for measuring drought stress effects.

  1. Leaf-architectured 3D Hierarchical Artificial Photosynthetic System of Perovskite Titanates Towards CO2 Photoreduction Into Hydrocarbon Fuels

    Science.gov (United States)

    Zhou, Han; Guo, Jianjun; Li, Peng; Fan, Tongxiang; Zhang, Di; Ye, Jinhua

    2013-01-01

    The development of an “artificial photosynthetic system” (APS) having both the analogous important structural elements and reaction features of photosynthesis to achieve solar-driven water splitting and CO2 reduction is highly challenging. Here, we demonstrate a design strategy for a promising 3D APS architecture as an efficient mass flow/light harvesting network relying on the morphological replacement of a concept prototype-leaf's 3D architecture into perovskite titanates for CO2 photoreduction into hydrocarbon fuels (CO and CH4). The process uses artificial sunlight as the energy source, water as an electron donor and CO2 as the carbon source, mimicking what real leaves do. To our knowledge this is the first example utilizing biological systems as “architecture-directing agents” for APS towards CO2 photoreduction, which hints at a more general principle for APS architectures with a great variety of optimized biological geometries. This research would have great significance for the potential realization of global carbon neutral cycle. PMID:23588925

  2. Effect of different levels of air pollution on photosynthetic activity of some lichens

    Directory of Open Access Journals (Sweden)

    Ewa Niewiadomska

    2014-01-01

    Full Text Available Four lichen species: Hypogymnia physodes, Pseudevernia furfuracea, Parmelia saxatilis, and Platismatia glauca were collected from two sites (S. Poland with a different air pollution level: "Kamienica valley" (less polluted and "Kopa" (more polluted. The thalli were compared with respect to their: net photosynthetic rate (PN, fluorescence parameters (Fv/Fm, Fm, Fm/Fo, chlorophyll a+b content, and phaeophytinization quotient (O.D.435/O.D.415. PN intensity, chlorophyll a+b and O.D.435/O.D.415 were reduced only in Pa furfuracea collected from Kopa, which is in agreement with the Hawksworth-Rose scale of sensitivity of lichens to air pollution. Fluorescence parameters were significantly lowered in all lichens coming from the more polluted site (except of Fv/Fm and Fm/F0 in P. saxatilis. Parameters based on chlorophyll fluorescence measurements enable to reveal the very early signs of decreased photosynthetical capacity of the thalli, caused by air pollution, before changes in the other photosynthetic parameters become mesurable.

  3. Effects of differnt juvenile mixed plantations on growth and photosynthetic physiology of pinus yunnanensis franch

    International Nuclear Information System (INIS)

    Zheng, Y.; Ou, G. L.; Chen, D. D.; Liu, G. Y.; Li, Q. Q.; Zhang, S. H.; Han, M. Y.; Chen, J. L.

    2017-01-01

    The growth characteristics, photosynthetic gas exchange features, physiological and biochemical resistance, and soil nutrition contents of different juvenile mixed plantations were analyzed. Moreover, the synergic effect mechanism of the different species was elucidated to improve the stand quality of Pinus yunnanensis Franch. plantations and guide the screening of P. yunnanensis mixed plantations. The mixed plantations were P. yunnanensis-Alnus nepalensis-Quercus acutissima, P. yunnanensis-A. nepalensis-Cyclobalanopsis glaucoides, and P. yunnanensis-Q. acutissima-C. glaucoides. Individual juvenile plantations of pure P. yunnanensis, A. nepalensis, Q. acutissima, and C. glaucoides were used as control groups. Results showed that pure P. yunnanensis juvenile plantation consumed more soil organic matter, total nitrogen (TN), total phosphorus (TP), and total potassium (TK) than the other plantations. This plantation also showed poorer growth characteristics, poorer photosynthetic capability, lower water utilization efficiency (WUE), and biochemical resistance in infertile soil, as shown by the nutrition and water competition. Increasing soil organic matters, TN, TP, and TK of the different mixed plantations evidently enhanced height, ground diameter growth rate, net photosynthetic rate (Pn), transpiration rate (Tr), WUE, carboxylation efficiency (CE), soluble sugar (SS) content, and superoxide dismutase (SOD) activity. Moreover, different mixed forests slightly influenced the characteristics of photosynthetic gas exchange and physiological and biochemical resistance of A. nepalensis. All stand types facilitated growth of tree height and basal diameter of Q. acutissima sapling. Although Q. acutissima inhibited physiological and biochemical resistance of leaves to a certain extent, they increased WUE significantly. Different stand types slightly influenced growth features, Pn, Tr, and WUE of C. glaucoides sapling. Moreover, they inhibited the osmotic adjustment system

  4. Photosynthetic epibionts and endobionts of Pacific oyster shells from oyster reefs in rocky versus mudflat shores.

    Directory of Open Access Journals (Sweden)

    Laurent Barillé

    Full Text Available The Pacific oyster, Crassostrea gigas (Thunberg, is the main bivalve species cultivated in the world. With global warming enabling its reproduction and larval survival at higher latitudes, this species is now recognized as invasive and creates wild oyster reefs globally. In this study, the spatial distribution of photosynthetic assemblages colonizing the shells of wild C. gigas was investigated on both a large scale (two contrasting types of reefs found in mudflats and rocky areas and a small scale (within individual shells using a hyperspectral imager. The microspatial distribution of all phototrophs was obtained by mapping the Normalized Difference Vegetation Index (NDVI. Second derivative (δδ analyses of hyperspectral images at 462, 524, 571 and 647 nm were subsequently applied to map diatoms, cyanobacteria, rhodophytes and chlorophytes, respectively. A concomitant pigment analysis was carried out by high performance liquid chromatography and completed by taxonomic observations. This study showed that there was high microalgal diversity associated with wild oyster shells and that there were differences in the structure of the phototropic assemblages depending on the type of reef. Namely, vertically-growing oysters in mudflat areas had a higher biomass of epizoic diatoms (hyperspectral proxy at δδ462 nm and were mainly colonized by species of the genera Navicula, Nitzschia and Hippodonta, which are epipelic or motile epipsammic. The assemblages on the horizontal oysters contained more tychoplanktonic diatoms (e.g. Thalassiosira pseudonana, T. proschkinae and Plagiogrammopsis vanheurckii. Three species of boring cyanobacteria were observed for both types of reef: Mastigocoleus testarum, Leptolyngbya terrebrans, and Hyella caespistosa, but the second derivative analysis at 524 nm showed a significantly higher biomass for the horizontally-growing oysters. There was no biomass difference for the boring chlorophyte assemblages (δδ647 nm, with

  5. Measurement and estimation of photosynthetically active radiation from 1961 to 2011 in Central China

    International Nuclear Information System (INIS)

    Wang, Lunche; Gong, Wei; Li, Chen; Lin, Aiwen; Hu, Bo; Ma, Yingying

    2013-01-01

    Highlights: • 6-Year observations were used to show the temporal variability of PAR and PAR/G. • Dependence of PAR on clearness index was studied in model development. • New developed models performed very well at different time scales. • The new all-weather model provided good estimates of PAR at two other sites. • Long-term variations of PAR from 1961 to 2011 in Central China were analyzed. - Abstract: Measurements of photosynthetically active radiation (PAR) and global solar radiation (G) at WHU, Central China during 2006–2011 were used to investigate the seasonal characteristics of PAR and PAR/G (PAR fraction). Both PAR and PAR fraction showed similar seasonal features that peaked in values during summer and reached their lowest in winter with annual mean values being 22.39 mol m −2 d −1 and 1.9 mol M J −1 respectively. By analyzing the dependence of PAR on cosine of solar zenith angle and clearness index at WHU, an efficient all-weather model was developed for estimating PAR values under various sky conditions, which also produced accepted estimations with high accuracy at Lhasa and Fukang. PAR dataset was then reconstructed from G for 1961–2011 through the new developed model. Annual mean daily PAR was about 23.12 mol m −2 d −1 , there was a significant decreasing trend (11.2 mol m −2 per decade) during the last 50 years in Central China, the decreases were sharpest in summer (−24.67 mol m −2 per decade) with relatively small decreases being observed in spring. Meanwhile, results also revealed that PAR began to increase at a rate of 0.1 mol m −2 per year from 1991 to 2011, which was in consistent with variation patterns of global solar radiation in the study area. The proposed all-weather PAR model would be of vital importance for ecological modeling, atmospheric environment, agricultural processes and solar energy application

  6. Worldwide variation in within-canopy photosynthetic acclimation: differences in temporal and environmental controls among plant functional types

    Science.gov (United States)

    Niinemets, Ülo; Keenan, Trevor

    2017-04-01

    Major light gradients, characteristically 10- to 50-fold, constitute the most prominent feature of plant canopies. These gradients drive within-canopy variation in foliage structural, chemical and physiological traits. As a key acclimation response to variation in light availability, foliage photosynthetic capacity per area (Aarea) increases with increasing light availability within the canopy, maximizing whole canopy photosynthesis. Recently, a worldwide database including 831 within-canopy gradients with standardized light estimates for 304 species belonging to major vascular plant functional types was constructed and within-canopy variation in photosynthetic acclimation was characterized (Niinemets Ü, Keenan TF, Hallik L (2015) Tansley review. A worldwide analysis of within-canopy variations in leaf structural, chemical and physiological traits across plant functional types. The New Phytologist 205: 973-993). However, the understanding of how within-canopy photosynthetic gradients vary during the growing season and in response to site and stand characteristics is still limited. Here we analyzed temporal, environmental and site (nutrient availability, stand density, ambient CO2 concentration, water availability) sources of variation in within-canopy photosynthetic acclimation in different plant functional types. Variation in key structural (leaf dry mass per unit area, MA), chemical (nitrogen content per dry mass, NM, and area, NA) and physiological (photosynthetic nitrogen use efficiency, EN) photosynthetic capacity per dry mass, Amass and area, Aarea) was examined. The analysis demonstrates major, typically 1.5-2-fold, time-, environment and site-dependent modifications in within-canopy variation in foliage photosynthetic capacity. However, the magnitude and direction of temporal and environmental variations in plasticity significantly varied among functional types. Species with longer leaf life span and low rates of canopy expansion or flush-type canopy

  7. Ultrafast time-resolved carotenoid to-bacteriochlorophyll energy transfer in LH2 complexes from photosynthetic bacteria.

    Science.gov (United States)

    Cong, Hong; Niedzwiedzki, Dariusz M; Gibson, George N; LaFountain, Amy M; Kelsh, Rhiannon M; Gardiner, Alastair T; Cogdell, Richard J; Frank, Harry A

    2008-08-28

    Steady-state and ultrafast time-resolved optical spectroscopic investigations have been carried out at 293 and 10 K on LH2 pigment-protein complexes isolated from three different strains of photosynthetic bacteria: Rhodobacter (Rb.) sphaeroides G1C, Rb. sphaeroides 2.4.1 (anaerobically and aerobically grown), and Rps. acidophila 10050. The LH2 complexes obtained from these strains contain the carotenoids, neurosporene, spheroidene, spheroidenone, and rhodopin glucoside, respectively. These molecules have a systematically increasing number of pi-electron conjugated carbon-carbon double bonds. Steady-state absorption and fluorescence excitation experiments have revealed that the total efficiency of energy transfer from the carotenoids to bacteriochlorophyll is independent of temperature and nearly constant at approximately 90% for the LH2 complexes containing neurosporene, spheroidene, spheroidenone, but drops to approximately 53% for the complex containing rhodopin glucoside. Ultrafast transient absorption spectra in the near-infrared (NIR) region of the purified carotenoids in solution have revealed the energies of the S1 (2(1)Ag-)-->S2 (1(1)Bu+) excited-state transitions which, when subtracted from the energies of the S0 (1(1)Ag-)-->S2 (1(1)Bu+) transitions determined by steady-state absorption measurements, give precise values for the positions of the S1 (2(1)Ag-) states of the carotenoids. Global fitting of the ultrafast spectral and temporal data sets have revealed the dynamics of the pathways of de-excitation of the carotenoid excited states. The pathways include energy transfer to bacteriochlorophyll, population of the so-called S* state of the carotenoids, and formation of carotenoid radical cations (Car*+). The investigation has found that excitation energy transfer to bacteriochlorophyll is partitioned through the S1 (1(1)Ag-), S2 (1(1)Bu+), and S* states of the different carotenoids to varying degrees. This is understood through a consideration of the

  8. Effect of planting density on fruit size, light-interception and photosynthetic activity of vertically trained watermelon (Citrullus lanatus (Thunb.) Matsum. et Nakai) plants

    International Nuclear Information System (INIS)

    Watanabe, S.; Nakano, Y.; Okano, K.

    2003-01-01

    Summary The effect of planting density on fruit size of vertically trained watermelon (Citrullus lanatus (Thunb.) Matsum. et Nakai) plants was investigated with regard to light - interception characteristics and photosynthetic production. Watermelon plants, grafted on bottle gourd, were grown in a glasshouse at different planting densities. Two vines per plant were allowed to grow and trained vertically. One hand-pollinated fruit per plant was set around the 15th node on either vine. The solar radiation and photosynthetic rate of individual leaves during fruit development period were determined by an integrated solarimeter film and a portable photosynthesis system, respectively. Fruit size was significantly decreased as the planting density increased, whereas soluble solids content of the fruits was affected little. The solar radiation and the photosynthetic rate of the individual leaves gradually decreased as the leaf position became lower at all planting densities on account of shading; those at lower leaves tended to decrease as the planting density increased. Fruit size was closely related to both the total solar radiation and the photosynthetic production per plant. In conclusion, the difference in fruit size among the planting densities is attributed to the photosynthetic productivity of the whole plant, which is mainly a function of the total solar radiation. This paper appears to be the first trial relating the influence of light interception and photosynthetic rates in high density plantings of vertically trained watermelon plants on fruit size

  9. Photosynthetic temperature responses of tree species in Rwanda: evidence of pronounced negative effects of high temperature in montane rainforest climax species.

    Science.gov (United States)

    Vårhammar, Angelica; Wallin, Göran; McLean, Christopher M; Dusenge, Mirindi Eric; Medlyn, Belinda E; Hasper, Thomas B; Nsabimana, Donat; Uddling, Johan

    2015-05-01

    The sensitivity of photosynthetic metabolism to temperature has been identified as a key uncertainty for projecting the magnitude of the terrestrial feedback on future climate change. While temperature responses of photosynthetic capacities have been comparatively well investigated in temperate species, the responses of tropical tree species remain unexplored. We compared the responses of seedlings of native cold-adapted tropical montane rainforest tree species with those of exotic warm-adapted plantation species, all growing in an intermediate temperature common garden in Rwanda. Leaf gas exchange responses to carbon dioxide (CO2 ) at different temperatures (20-40°C) were used to assess the temperature responses of biochemical photosynthetic capacities. Analyses revealed a lower optimum temperature for photosynthetic electron transport rates than for Rubisco carboxylation rates, along with lower electron transport optima in the native cold-adapted than in the exotic warm-adapted species. The photosynthetic optimum temperatures were generally exceeded by daytime peak leaf temperatures, in particular in the native montane rainforest climax species. This study thus provides evidence of pronounced negative effects of high temperature in tropical trees and indicates high susceptibility of montane rainforest climax species to future global warming. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  10. Photosynthetic temperature responses of tree species in Rwanda: evidence of pronounced negative effects of high temperature in montane rainforest climax species

    Science.gov (United States)

    Vårhammar, Angelica; Wallin, Göran; McLean, Christopher M.; Dusenge, Mirindi Eric; Medlyn, Belinda E.; Hasper, Thomas B.; Nsabimana, Donat; Uddling, Johan

    2015-04-01

    The sensitivity of photosynthetic metabolism to temperature has been identified as a key uncertainty for projecting the magnitude of the terrestrial feedback on future climate change. While temperature responses of photosynthetic capacities have been comparatively well investigated in temperate species, the responses of tropical tree species remain unexplored. We compared the responses of seedlings of native cold-adapted tropical montane rainforest tree species to exotic warm-adapted plantation species, all growing in an intermediate temperature common garden in Rwanda. Leaf gas exchange responses to CO2 at different temperatures (20 - 40 C) were used to assess the temperature responses of biochemical photosynthetic capacities. Analyses revealed a lower optimum temperature for photosynthetic electron transport rates than for Rubisco carboxylation rates, along with lower electron transport optima in the native cold-adapted than in the exotic warm-adapted species. The photosynthetic optimum temperatures were generally exceeded by daytime peak leaf temperatures, in particular in the native montane rainforest climax species. This study thus provides evidence of pronounced negative effects of high temperature in tropical trees and indicates high susceptibility of montane rainforest climax species to future global warming. (Reference: New Phytologist, in press)

  11. Light affects the chloroplast ultrastructure and post-storage photosynthetic performance of watermelon (Citrullus lanatus) plug seedlings.

    Science.gov (United States)

    Duan, Qingqing; Jiang, Wu; Ding, Ming; Lin, Ye; Huang, Danfeng

    2014-01-01

    Watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] plug seedlings were stored at 15°C in the light at a photosynthetic photon flux density of 15 µmol·m(-2)·s(-1) or in darkness for 6 days, to evaluate their chloroplast ultrastructure, and associated photosynthetic characteristics. Storage in the dark caused swelling, disordered granal arrangement, and starch grain disappearance in the chloroplasts. In contrast, the chloroplasts stored in the light were relatively normal. As a result, the light-stored seedlings had a significantly higher chlorophyll content, Fv/Fm, and Pn than did dark-stored seedlings. Regardless of whether the seedlings were stored in light or darkness, the Gs and Ls of the seedlings significantly decreased, while the Ci obviously increased when the Pn decreased after 6 days of storage. This result suggests that the decreased Pn is not solely a stomatal effect, as the effects on the chloroplasts contributed to this photosynthetic inhibition. Six days after transplanting, seedlings that were stored in the light or darkness for 2 or 4 days showed complete recovery of chloroplast ultrastructure, chlorophyll content, Fv/Fm, Gs and Pn. When the storage period increased to 6 days, the dark-stored seedlings had a significantly lower Fv/Fm and Pn than the light-stored and control seedlings 6 days after transplanting, which was mainly ascribed to incomplete recovery of chloroplast ultrastructure. Furthermore, the light-stored seedlings exhibited a significantly higher shoot dry weight during storage and a higher percentage dry weight increase after transplanting than the dark-stored seedlings. These effects were enhanced by prolonged storage (4 to 6 days). This study demonstrated that dim light during storage is beneficial for maintaining chloroplast ultrastructure as well as photosynthetic efficiency in watermelon seedlings, thus contributing to the rapid recovery of post-storage photosynthetic performance, which ensures the transplant quality

  12. Molecular and Photosynthetic Responses to Prolonged Darkness and Subsequent Acclimation to Re-Illumination in the Diatom Phaeodactylum tricornutum

    DEFF Research Database (Denmark)

    Nymark, Marianne; Valle, Kristi Collier; Hancke, Kasper

    2013-01-01

    and immediately utilize the available energy in photosynthesis and growth. We have investigated both the response to prolonged darkness and the re-acclimation to moderate intensity white irradiance (E = 100 µmol m−2 s−1) in the diatom Phaeodactylum tricornutum, using an integrated approach involving global......-introduction of the cells to the initial light conditions revealed 5) distinct expression profiles for nuclear genes involved in photosynthesis and those involved in photoprotection, 6) rapid rise in photosynthetic parameters (α and rETRmax) within 0.5 h of re-exposure to light despite a very modest de novo synthesis......Photosynthetic diatoms that live suspended throughout the water column will constantly be swept up and down by vertical mixing. When returned to the photic zone after experiencing longer periods in darkness, mechanisms exist that enable the diatoms both to survive sudden light exposure...

  13. Biological optimization systems for enhancing photosynthetic efficiency and methods of use

    Science.gov (United States)

    Hunt, Ryan W.; Chinnasamy, Senthil; Das, Keshav C.; de Mattos, Erico Rolim

    2012-11-06

    Biological optimization systems for enhancing photosynthetic efficiency and methods of use. Specifically, methods for enhancing photosynthetic efficiency including applying pulsed light to a photosynthetic organism, using a chlorophyll fluorescence feedback control system to determine one or more photosynthetic efficiency parameters, and adjusting one or more of the photosynthetic efficiency parameters to drive the photosynthesis by the delivery of an amount of light to optimize light absorption of the photosynthetic organism while providing enough dark time between light pulses to prevent oversaturation of the chlorophyll reaction centers are disclosed.

  14. Effect of space mutation of photosynthetic characteristics of soybean varieties

    International Nuclear Information System (INIS)

    Liu Xinlei; Ma Yansong; Luan Xiaoyan; Man Weiqun; Xu Dechun; Meng Lifen; Fu Lixin; Zhao Xiao'nan; Liu Qi

    2012-01-01

    In order to elucidate the response of the photosynthetic traits of soybean to space mutation, three soybean varieties (lines) of Heinong 48, Heinong 44 and Ha 2291-Y were carried by artificial satellite in 2006 and the net photo synthetic rate (Pn), stomatal conductance (Cond), intercellular CO 2 concentration (Ci) and stomatal resistance (Rs) from SP 1 to SP 4 generation were determined. The results showed that space mutation affected photosynthesis traits of soy bean. The photosynthetic rate of soybean varieties by space mutation occurred different levels of genetic variation and the positive mutation rate were higher. Coefficient of variation among generations were SP 2 >SP 3 >SP 4 >CK. Results suggest that space mutation can effectively create soybean materials with higher photosynthetic rate. (authors)

  15. Superradiance Transition and Nonphotochemical Quenching in Photosynthetic Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Berman, Gennady Petrovich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nesterov, Alexander [Universidad de Guadalajara, Departamento de Fısica, Jalisco (Mexico); Lopez, Gustavo [Universidad de Guadalajara, Departamento de Fısica, Jalisco (Mexico); Sayre, Richard Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-04-23

    Photosynthetic organisms have evolved protective strategies to allow them to survive in cases of intense sunlight fluctuation with the development of nonphotochemical quenching (NPQ). This process allows light harvesting complexes to transfer the excess sunlight energy to non-damaging quenching channels. This report compares the NPQ process with the superradiance transition (ST). We demonstrated that the maximum of the NPQ efficiency is caused by the ST to the sink associated with the CTS. However, experimental verifications are required in order to determine whether or not the NPQ regime is associated with the ST transition for real photosynthetic complexes. Indeed, it can happen that, in the photosynthetic apparatus, the NPQ regime occurs in the “non-optimal” region of parameters, and it could be independent of the ST.

  16. SOUR CHERRY (Prunus cerasus L. GENETIC VARIABILITY AND PHOTOSYNTHETIC EFFICIENCY DURING DROUGHT

    Directory of Open Access Journals (Sweden)

    Marija Viljevac

    2012-12-01

    Full Text Available Sour cherry is an important fruit in Croatian orchards. Cultivar Oblačinska is predominant in existing orchards with noted intracultivar phenotypic heterogeneity. In this study, the genetic variability of 22 genotypes of cvs. Oblačinska, Maraska and Cigančica, as well as standard cvs. Kelleris 14, Kelleris 16, Kereška, Rexelle and Heimann conserved were investigated. Two types of molecular markers were used: microsatellite markers (SSR in order to identify intercultivar, and AFLP in order to identify intracultivar variabilities. A set of 12 SSR markers revealed small genetic distance between cvs. Maraska and Oblačinska while cv. Cigančica is affined to cv. Oblačinska. Furthermore, cvs. Oblačinska, Cigančica and Maraska were characterized compared to standard ones. AFLP markers didn`t confirm significant intracultivar variability of cv. Oblačinska although the variability has been approved at the morphological, chemical and pomological level. Significant corelation between SSR and AFLP markers was found. Identification of sour cherry cultivars tolerant to drought will enable the sustainability of fruit production with respect to the climate change in the future. For this purpose, the tolerance of seven sour cherry genotypes (cvs. Kelleris 16, Maraska, Cigančica and Oblačinska represented by 4 genotypes: OS, 18, D6 and BOR to drought conditions was tested in order to isolate genotypes with the desired properties. In the greenhouse experiment, cherry plants were exposed to drought stress. The leaf relative water content, OJIP test parameters which specify efficiency of the photosynthetic system based on measurements of chlorophyll a fluorescence, and concentrations of photo-synthetic pigments during the experiment were measured as markers of drought tolerance. Photosynthetic performance index (PIABS comprises three key events in the reaction centre of photosystem II affecting the photosynthetic activity: the absorption of energy

  17. PHOTOSYNTHETIC EFFICIENCY IN JUVENILE STAGE AND WINTER BARLEY BREEDING FOR IMPROVED GRAIN YIELD AND STABILITY

    Directory of Open Access Journals (Sweden)

    Josip Kovačević

    2011-06-01

    Full Text Available Photosynthetic efficiency parameters (Fv/Fm, ET0/ABS and PIABS were investigated at the end of tillering stage of winter barley grown in stress environment (21.3% vol. water content of soil and control (water content 30.4% vol. in relation to grain yield per vegetative pot. The trial was conducted in vegetative pots according to the RBD method of two-factorial experiment with 10 winter barley cultivars (7 tworowed and 3 six-rowed and 2 treatments in 3 repetitions. The stressed variant was exposed to water reduction three times (end of tillering stage, flag leaf to beginning of heading stage, grain filling stage. From sowing to maturity, the air temperature varied from -3.9°C to 32.9°C and water content from 16.4 % to 39.0 % of soil volume in vegetative pot. Significant differences were found for grain yield among the cultivars. The short-term drought stress caused significant reductions in grain yield per pot. The photosynthetic efficiency parameters were significant between cultivars, but significant effects for treatments and interaction were only detected for the Fv/Fm parameter. Photosynthetic efficiency parameters did not have significant correlation coefficients with grain yield and its stability in both treatments. Stability indexes of the parameters PIABS and Fv/Fm had positive but not significant correlations with grain yield in stressed variant (0.465 and 0.452 and stability index of grain yield (0.337 and 0.481.

  18. miR-155, identified as anti-metastatic by global miRNA profiling of a metastasis model, inhibits cancer cell extravasation and colonization in vivo and causes significant signaling alterations

    DEFF Research Database (Denmark)

    Gravgaard, Karina Hedelund; Terp, Mikkel G; Lund, Rikke R

    2015-01-01

    To gain insight into miRNA regulation in metastasis formation, we used a metastasis cell line model that allows investigation of extravasation and colonization of circulating cancer cells to lungs in mice. Using global miRNA profiling, 28 miRNAs were found to exhibit significantly altered...... proliferation or apoptosis in established lung tumors. To identify proteins regulated by miR-155 and thus delineate its function in our cell model, we compared the proteome of xenograft tumors derived from miR-155-overexpressing CL16 cells and CL16 control cells using mass spectrometry-based proteomics. >4......,000 proteins were identified, of which 92 were consistently differentially expressed. Network analysis revealed that the altered proteins were associated with cellular functions such as movement, growth and survival as well as cell-to-cell signaling and interaction. Downregulation of the three metastasis...

  19. Overlapping toxic effect of long term thallium exposure on white mustard (Sinapis alba L.) photosynthetic activity.

    Science.gov (United States)

    Mazur, Radosław; Sadowska, Monika; Kowalewska, Łucja; Abratowska, Agnieszka; Kalaji, Hazem M; Mostowska, Agnieszka; Garstka, Maciej; Krasnodębska-Ostręga, Beata

    2016-09-02

    Heavy metal exposure affect plant productivity by interfering, directly and indirectly, with photosynthetic reactions. The toxic effect of heavy metals on photosynthetic reactions has been reported in wide-ranging studies, however there is paucity of data in the literature concerning thallium (Tl) toxicity. Thallium is ubiquitous natural trace element and is considered the most toxic of heavy metals; however, some plant species, such as white mustard (Sinapis alba L.) are able to accumulate thallium at very high concentrations. In this study we identified the main sites of the photosynthetic process inhibited either directly or indirectly by thallium, and elucidated possible detoxification mechanisms in S. alba. We studied the toxicity of thallium in white mustard (S. alba) growing plants and demonstrated that tolerance of plants to thallium (the root test) decreased with the increasing Tl(I) ions concentration in culture media. The root growth of plants exposed to Tl at 100 μg L(-1) for 4 weeks was similar to that in control plants, while in plants grown with Tl at 1,000 μg L(-1) root growth was strongly inhibited. In leaves, toxic effect became gradually visible in response to increasing concentration of Tl (100 - 1,000 μg L(-1)) with discoloration spreading around main vascular bundles of the leaf blade; whereas leaf margins remained green. Subsequent structural analyses using chlorophyll fluorescence, microscopy, and pigment and protein analysis have revealed different effects of varying Tl concentrations on leaf tissue. At lower concentration partial rearrangement of the photosynthetic complexes was observed without significant changes in the chloroplast structure and the pigment and protein levels. At higher concentrations, the decrease of PSI and PSII quantum yields and massive oxidation of pigments was observed in discolored leaf areas, which contained high amount of Tl. Substantial decline of the photosystem core proteins and disorder of the

  20. Seasonal response of photosynthetic electron transport and energy dissipation in the eighth year of exposure to elevated atmospheric CO2 (FACE) in Pinus taeda (loblolly pine)

    International Nuclear Information System (INIS)

    Logan, B.A.; Combs, A.; Kent, R.; Stanley, L.; Myers, K.; Tissue, D.T.; Western Sydney Univ., Richmond, NSW

    2009-01-01

    This study investigated the biological adaptation of loblolly pine following long-term seasonal exposure to elevated carbon dioxide (CO 2 ) partial pressures (pCO 2 ). Exposure to elevated atmospheric CO 2 (pCO 2 ) usually results in significant stimulation in light-saturated rates of photosynthetic CO 2 assimilation. Plants are protected against photoinhibition by biochemical processes known as photoprotection, including energy dissipation, which converts excess absorbed light energy into heat. This study was conducted in the eighth year of exposure to elevated pCO 2 at the Duke FACE site. The effect of elevated pCO 2 on electron transport and energy dissipation in the pine trees was examined by coupling the analyses of the capacity for photosynthetic oxygen (O 2 ) evolution, chlorophyll fluorescence emission and photosynthetic pigment composition with measurements of net photosynthetic CO 2 assimilation (Asat). During the summer growing season, Asat was 50 per cent higher in current-year needles and 24 per cent higher in year-old needles in elevated pCO 2 in comparison with needles of the same age cohort in ambient pCO 2 . Thus, older needles exhibited greater photosynthetic down-regulation than younger needles in elevated pCO 2 . In the winter, Asat was not significantly affected by growth pCO 2 . Asat was lower in winter than in summer. Growth at elevated pCO 2 had no significant effect on the capacity for photosynthetic oxygen evolution, photosystem 2 efficiencies, chlorophyll content or the size and conversion state of the xanthophyll cycle, regardless of season or needle age. There was no evidence that photosynthetic electron transport or photoprotective energy dissipation responded to compensate for the effects of elevated pCO 2 on Calvin cycle activity. 73 refs., 4 figs

  1. Optimal fold symmetry of LH2 rings on a photosynthetic membrane.

    Science.gov (United States)

    Cleary, Liam; Chen, Hang; Chuang, Chern; Silbey, Robert J; Cao, Jianshu

    2013-05-21

    An intriguing observation of photosynthetic light-harvesting systems is the N-fold symmetry of light-harvesting complex 2 (LH2) of purple bacteria. We calculate the optimal rotational configuration of N-fold rings on a hexagonal lattice and establish two related mechanisms for the promotion of maximum excitation energy transfer (EET). (i) For certain fold numbers, there exist optimal basis cells with rotational symmetry, extendable to the entire lattice for the global optimization of the EET network. (ii) The type of basis cell can reduce or remove the frustration of EET rates across the photosynthetic network. We find that the existence of a basis cell and its type are directly related to the number of matching points S between the fold symmetry and the hexagonal lattice. The two complementary mechanisms provide selection criteria for the fold number and identify groups of consecutive numbers. Remarkably, one such group consists of the naturally occurring 8-, 9-, and 10-fold rings. By considering the inter-ring distance and EET rate, we demonstrate that this group can achieve minimal rotational sensitivity in addition to an optimal packing density, achieving robust and efficient EET. This corroborates our findings i and ii and, through their direct relation to S, suggests the design principle of matching the internal symmetry with the lattice order.

  2. Influence of Sky Conditions on Estimation of Photosynthetic Photon Flux Density for Agricultural Ecosystem

    Science.gov (United States)

    Yamashita, M.; Yoshimura, M.

    2018-04-01

    Photosynthetic photon flux density (PPFD: µmol m-2 s-1) is indispensable for plant physiology processes in photosynthesis. However, PPFD is seldom measured, so that PPFD has been estimated by using solar radiation (SR: W m-2) measured in world wide. In method using SR, there are two steps: first to estimate photosynthetically active radiation (PAR: W m-2) by the fraction of PAR to SR (PF) and second: to convert PAR to PPFD using the ratio of quanta to energy (Q / E: µmol J-1). PF and Q/E usually have been used as the constant values, however, recent studies point out that PF and Q / E would not be constants under various sky conditions. In this study, we use the numeric data of sky-conditions factors such cloud cover, sun appearance/hiding and relative sky brightness derived from whole-sky image processing and examine the influences of sky-conditions factors on PF and Q / E of global and diffuse PAR. Furthermore, we discuss our results by comparing with the existing methods.

  3. Terrestrial biosphere models underestimate photosynthetic capacity and CO2 assimilation in the Arctic.

    Science.gov (United States)

    Rogers, Alistair; Serbin, Shawn P; Ely, Kim S; Sloan, Victoria L; Wullschleger, Stan D

    2017-12-01

    Terrestrial biosphere models (TBMs) are highly sensitive to model representation of photosynthesis, in particular the parameters maximum carboxylation rate and maximum electron transport rate at 25°C (V c,max.25 and J max.25 , respectively). Many TBMs do not include representation of Arctic plants, and those that do rely on understanding and parameterization from temperate species. We measured photosynthetic CO 2 response curves and leaf nitrogen (N) content in species representing the dominant vascular plant functional types found on the coastal tundra near Barrow, Alaska. The activation energies associated with the temperature response functions of V c,max and J max were 17% lower than commonly used values. When scaled to 25°C, V c,max.25 and J max.25 were two- to five-fold higher than the values used to parameterize current TBMs. This high photosynthetic capacity was attributable to a high leaf N content and the high fraction of N invested in Rubisco. Leaf-level modeling demonstrated that current parameterization of TBMs resulted in a two-fold underestimation of the capacity for leaf-level CO 2 assimilation in Arctic vegetation. This study highlights the poor representation of Arctic photosynthesis in TBMs, and provides the critical data necessary to improve our ability to project the response of the Arctic to global environmental change. No claim to original US Government works. New Phytologist © 2017 New Phytologist Trust.

  4. The Arabidopsis ppi1 Mutant Is Specifically Defective in the Expression, Chloroplast Import, and Accumulation of Photosynthetic ProteinsW⃞

    Science.gov (United States)

    Kubis, Sybille; Baldwin, Amy; Patel, Ramesh; Razzaq, Azam; Dupree, Paul; Lilley, Kathryn; Kurth, Joachim; Leister, Dario; Jarvis, Paul

    2003-01-01

    The import of nucleus-encoded proteins into chloroplasts is mediated by translocon complexes in the envelope membranes. A component of the translocon in the outer envelope membrane, Toc34, is encoded in Arabidopsis by two homologous genes, atTOC33 and atTOC34. Whereas atTOC34 displays relatively uniform expression throughout development, atTOC33 is strongly upregulated in rapidly growing, photosynthetic tissues. To understand the reason for the existence of these two related genes, we characterized the atTOC33 knockout mutant ppi1. Immunoblotting and proteomics revealed that components of the photosynthetic apparatus are deficient in ppi1 chloroplasts and that nonphotosynthetic chloroplast proteins are unchanged or enriched slightly. Furthermore, DNA array analysis of 3292 transcripts revealed that photosynthetic genes are moderately, but specifically, downregulated in ppi1. Proteome differences in ppi1 could be correlated with protein import rates: ppi1 chloroplasts imported the ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit and 33-kD oxygen-evolving complex precursors at significantly reduced rates, but the import of a 50S ribosomal subunit precursor was largely unaffected. The ppi1 import defect occurred at the level of preprotein binding, which is consistent with a role for atToc33 during preprotein recognition. The data suggest that atToc33 is involved preferentially in the import of photosynthetic proteins and, by extension, that atToc34 is involved in the import of nonphotosynthetic chloroplast proteins. PMID:12897258

  5. Foliar nitrogen and potassium applications improve photosynthetic activities and water relations in sunflower under moisture deficit condition

    International Nuclear Information System (INIS)

    Hussain, R.A.; Ahmad, R.

    2016-01-01

    This study investigated the influence of foliar supplementation of nitrogen (N) potassium (K) and their combination on photosynthetic activities, physiological indices and water relations of two sunflower (Helianthus annuus L.) hybrids Hysen-33 and LG-5551 under water deficit condition. Studies were conducted in a wire-house at Nuclear Institute for Agriculture and Biology, Faisalabad, Pakistan. Treatments were two water stress levels [100 (control) and 60% field capacity (water deficit)], six levels of foliar spray (no spray, water spray, 1% N, 1% K, 0.5% N + 0.5% K and 1% N + 1% K) and each treatment was replicated three times. Results showed that water stress reduced the photosynthetic activities: Pn (photosynthetic rate), E (rate of tanspiration) and gs (stomatal conductance) and water relations i.e., pie w (water potential), pie s (osmotic potential) and pie p (turgor potential) . Soil moisture deficit also significantly reduced the plant height, root length, fresh and dry matter which consequently affected the plant height stress tolerance index (PHSI), root length stress tolerance index (RLSI) and dry matter stress tolerance index (DMSI) in both sunflower hybrids. However, foliar supplementation with N and K or N+K improved the photosynthetic activities, water relations and physiological indices of both the sunflower hybrids. The findings of present study suggest that application of N+K is necessary to have high plant productivity. (author)

  6. The photosynthetic responses to stocking depth and algal mat density in the farmed seaweed Gracilaria lemaneiformis (Gracilariales, Rhodophyta).

    Science.gov (United States)

    Jiang, Heng; Zou, Dinghui; Chen, Weizhou; Yang, Yufeng

    2017-11-01

    The branches and mass of Gracilaria lemaneiformis increase with growth season, and the thalli sink to deeper depths with increasing biomass density during maricultivation. The changing depth and algal mat density may affect the physiology of the algae. In the present study, the photosynthetic behaviors regarding different biomass densities in G. lemaneiformis thalli collected from different stocking depths were determined, to examine how photosynthesis of this farmed alga was affected by the growth depths and algal mat densities. Our results showed that the chlorophyll a (Chl a), carotenoids (Car), phycoerythrin (PE) contents, and irradiance-saturated maximum photosynthetic rates (P max ) of the deeper layer-grown algae were significantly increased relative to the surface layer-grown algae. The P max , apparent photosynthetic efficiency (α) and dark respiration rate (R d ) of G. lemaneiformis thalli, were reduced, whereas the irradiance saturation points (I k ) were increased, with the increasing algal mat density. We proposed that appropriate measures are needed to trade off the stocking depth and biomass density, in an effort to maintain a relative high photosynthetic productivity during G. lemaneiformis maricultivation.

  7. Contrasting Responses of Marine and Freshwater Photosynthetic Organisms to UVB Radiation: A Meta-Analysis

    KAUST Repository

    Jin, Peng; Duarte, Carlos M.; Agusti, Susana

    2017-01-01

    artificial lamps. We found that marine photosynthetic organisms tend to be more sensitive than freshwater photosynthetic organisms to UVB radiation; responses to either decreased or increased UVB radiation vary among taxa; the mortality rate is the most

  8. On the photosynthetic and devlopmental responses of leaves to the spectral composition of light

    NARCIS (Netherlands)

    Hogewoning, S.W.

    2010-01-01

    Key words: action spectrum, artificial solar spectrum, blue light, Cucumis sativus, gas-exchange, light-emitting diodes (LEDs), light interception, light quality, non-photosynthetic pigments, photo-synthetic capacity, photomorphogenesis, photosystem excitation balance, quantum yield, red light.

  9. Rubisco mutants of Chlamydomonas reinhardtii enhance photosynthetic hydrogen production.

    Science.gov (United States)

    Pinto, T S; Malcata, F X; Arrabaça, J D; Silva, J M; Spreitzer, R J; Esquível, M G

    2013-06-01

    Molecular hydrogen (H2) is an ideal fuel characterized by high enthalpy change and lack of greenhouse effects. This biofuel can be released by microalgae via reduction of protons to molecular hydrogen catalyzed by hydrogenases. The main competitor for the reducing power required by the hydrogenases is the Calvin cycle, and rubisco plays a key role therein. Engineered Chlamydomonas with reduced rubisco levels, activity and stability was used as the basis of this research effort aimed at increasing hydrogen production. Biochemical monitoring in such metabolically engineered mutant cells proceeded in Tris/acetate/phosphate culture medium with S-depletion or repletion, both under hypoxia. Photosynthetic activity, maximum photochemical efficiency, chlorophyll and protein levels were all measured. In addition, expression of rubisco, hydrogenase, D1 and Lhcb were investigated, and H2 was quantified. At the beginning of the experiments, rubisco increased followed by intense degradation. Lhcb proteins exhibited monomeric isoforms during the first 24 to 48 h, and D1 displayed sensitivity under S-depletion. Rubisco mutants exhibited a significant decrease in O2 evolution compared with the control. Although the S-depleted medium was much more suitable than its complete counterpart for H2 production, hydrogen release was observed also in sealed S-repleted cultures of rubisco mutated cells under low-moderate light conditions. In particular, the rubisco mutant Y67A accounted for 10-15-fold higher hydrogen production than the wild type under the same conditions and also displayed divergent metabolic parameters. These results indicate that rubisco is a promising target for improving hydrogen production rates in engineered microalgae.

  10. Effects of gibberellic acid on growth and photosynthetic pigments of ...

    African Journals Online (AJOL)

    The aim of this study was to improve growth performance by enhancing the photosynthetic pigments and enzyme carbonic anhydrase (CA) activity of Hibiscus sabdariffa L. (cv. Sabahia 17) under NaCl stress. Under non-saline condition, application of GA3 enhanced growth parameters (shoot length, shoot fresh weight (FW) ...

  11. Continuous Cultivation of Photosynthetic Bacteria for Fatty Acids Production

    DEFF Research Database (Denmark)

    Kim, Dong-Hoon; Lee, Ji-Hye; Hwang, Yuhoon

    2013-01-01

    In the present work, we introduced a novel approach for microbial fatty acids (FA) production. Photosynthetic bacteria, Rhodobacter sphaeroides KD131, were cultivated in a continuous-flow, stirred-tank reactor (CFSTR) at various substrate (lactate) concentrations.At hydraulic retention time (HRT)....... sphaeroides was around 35% of dry cell weight, mainly composed of vaccenic acid (C18:1, omega-7)....

  12. Effect of Photosynthetic Photon Flux Density on Carboxylation Efficiency 1

    Science.gov (United States)

    Weber, James A.; Tenhunen, John D.; Gates, David M.; Lange, Otto L.

    1987-01-01

    The effect of photosynthetic photon flux density (PPFD) on photosynthetic response (A) to CO2 partial pressures between 35 pascals and CO2 compensation point (Γ) was investigated, especially below PPFD saturation. Spinacia oleracea cv `Atlanta,' Glycine max cv `Clark,' and Arbutus unedo were studied in detail. The initial slope of the photosynthetic response to CO2 (∂A/∂C[Γ]) was constant above a PPFD of about 500 to 600 micromoles per square meter per second for all three species; but declined rapidly with PPFD below this critical level. For Γ there was also a critical PPFD (approximately 200 micromoles per square meter per second for S. oleracea and G. max; 100 for A. unedo) above which Γ was essentially constant, but below which Γ increased with decreasing PPFD. All three species showed a dependence of ∂A/∂C(Γ) on PPFD at low PPFD. Simulated photosynthetic responses obtained with a biochemically based model of whole-leaf photosynthesis were similar to measured responses. PMID:16665640

  13. Coherent memory functions for finite systems: hexagonal photosynthetic unit

    International Nuclear Information System (INIS)

    Barvik, I.; Herman, P.

    1990-10-01

    Coherent memory functions entering the Generalized Master Equation are presented for an hexagonal model of a photosynthetic unit. Influence of an energy heterogeneity on an exciton transfer is an antenna system as well as to a reaction center is investigated. (author). 9 refs, 3 figs

  14. Effects of 1-butanol, neomycin and calcium on the photosynthetic ...

    African Journals Online (AJOL)

    ajl yemi

    Institute of Food Crops, Jiangsu High Quality Rice R&D Center, Jiangsu Academy of Agricultural Sciences, Nanjing,. Jiangsu Province, 210014, China. Accepted 31 October, 2011. The effects .... and blue light source under the open system, with the following conditions: 1200 µmol m-2s-1 photosynthetic photon flux density.

  15. Photosynthetic behaviour of Arabidopsis thaliana (Pa-1 accession ...

    African Journals Online (AJOL)

    The growth reduction observed in many plants caused by salinity is often associated with a decrease in their photosynthetic capacity. This effect could be associated with the partial stomatal closure and/or the non-stomatal limitation which involves the decrease in ribulose-1,5-bisphosphate carboxylase oxygenase ...

  16. Variability of photosynthetic pigments in the Colombian Pacific ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 111; Issue 3. Variability of photosynthetic pigments in the Colombian Pacific Ocean and its relationship with the wind field using ADEOS-I data. Efrain Rodriguez-Rubio Jose Stuardo. Volume 111 Issue 3 September 2002 pp 227-236 ...

  17. Photosynthetic Responses of Seedlings of two Indigenous Plants ...

    African Journals Online (AJOL)

    Bheema

    ABSTRACT. The potential role of exotic tree plantations in facilitating successional processes on degraded areas was evaluated in southern Ethiopia, Munessa-Shashemene forest, by examining photosynthetic responses of Bersamaabyssinica Fres. and Croton macrostachyusDel. seedlings naturally grown inside ...

  18. Abscisic acid effects on water and photosynthetic characteristics of ...

    African Journals Online (AJOL)

    The aim of this study is to compare the water and photosynthetic characteristics of two xerophilic ecotypes of Atriplex halimus (L.). Seeds collected from two different sites Djelfa and Oran are germinated in controlled greenhouse. After 6 months, the plantlets were treated 21 days with increasing concentrations of abscisic ...

  19. An Improved Method for Extraction and Separation of Photosynthetic Pigments

    Science.gov (United States)

    Katayama, Nobuyasu; Kanaizuka, Yasuhiro; Sudarmi, Rini; Yokohama, Yasutsugu

    2003-01-01

    The method for extracting and separating hydrophobic photosynthetic pigments proposed by Katayama "et al." ("Japanese Journal of Phycology," 42, 71-77, 1994) has been improved to introduce it to student laboratories at the senior high school level. Silica gel powder was used for removing water from fresh materials prior to…

  20. Photosynthetic incorporation of 14C by Stevia rebaudiana

    International Nuclear Information System (INIS)

    Ferraresi, M. de L.; Ferraresi Filho, O.; Bracht, A.

    1985-01-01

    The photosynthetic incorporation of 14 by Stevia rebaudiana specimens was investigated. The 14 C incorporation, when the isotope was furnished to the plant in form of 14 CO 2 , was rapid. After 24 hours, the radioactivity has been incorporated into a great number of compounds including pigments, terpenes, glucose, cellulose and also stevioside and its derivatives. (M.A.C.) [pt

  1. effect of ambient levels of ozone on photosynthetic components

    African Journals Online (AJOL)

    ACSS

    To clarify the long-term effects of ambient levels of tropospheric ozone (O3) on ... (Rubisco), thus contributing to the reduction in net photosynthetic rate at the .... USA). During the measurements, atmospheric. CO2 concentrations, air ...... productivity and implications for climate change. Annual Review of Plant Biology 63:.

  2. Non-photosynthetic plastids as hosts for metabolic engineering.

    Science.gov (United States)

    Mellor, Silas Busck; Behrendorff, James B Y H; Nielsen, Agnieszka Zygadlo; Jensen, Poul Erik; Pribil, Mathias

    2018-04-13

    Using plants as hosts for production of complex, high-value compounds and therapeutic proteins has gained increasing momentum over the past decade. Recent advances in metabolic engineering techniques using synthetic biology have set the stage for production yields to become economically attractive, but more refined design strategies are required to increase product yields without compromising development and growth of the host system. The ability of plant cells to differentiate into various tissues in combination with a high level of cellular compartmentalization represents so far the most unexploited plant-specific resource. Plant cells contain organelles called plastids that retain their own genome, harbour unique biosynthetic pathways and differentiate into distinct plastid types upon environmental and developmental cues. Chloroplasts, the plastid type hosting the photosynthetic processes in green tissues, have proven to be suitable for high yield protein and bio-compound production. Unfortunately, chloroplast manipulation often affects photosynthetic efficiency and therefore plant fitness. In this respect, plastids of non-photosynthetic tissues, which have focused metabolisms for synthesis and storage of particular classes of compounds, might prove more suitable for engineering the production and storage of non-native metabolites without affecting plant fitness. This review provides the current state of knowledge on the molecular mechanisms involved in plastid differentiation and focuses on non-photosynthetic plastids as alternative biotechnological platforms for metabolic engineering. © 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  3. Effect of maize seed laser irradiation on plant photosynthetic activity

    International Nuclear Information System (INIS)

    Antonov, M.; Stanev, V.; Velichkov, D.; Tsonev, Ts.

    1986-01-01

    Investigations were made with the two hybrids, H-708 and P x -20. The seeds were irradiated by a helium-neon quantum generator (L'vov-1 Electronica) with output power of 24 MW and 632.8 nm wave length. Once and twice irradiated seeds were sown on the 2nd, 5th and 10th day post irradiation. Changes in leaf area, chlorophyll content in the leaves, photosynthetic rate and its dependence on temperature and light, transpiration, stomatal resistance to CO 2 and total dry matter of the overground plant part were traced. Seed irradiation with laser rays did not affect the chlorophyll content of the leaves. The photosynthetic rate did not depend on the cultivar characteristics of the crop. Single and repeated irradiation of the hybrid H-708 in most case enhanced photosynthetic rate, but a similar effect was not observed in P x -20. Transpiration and CO 2 stomatal resistance were not equally affected by radiation. Laser rays enhanced the ability of the photosynthetic apparatus of the entire plants to use more efficiently high light intensities. The leaf area and the total plant dry matter increased in case of sowing on the 2nd and 5th day and a single irradiation and in case of sowing on the 5th and 10th day and twice repeated irradiations

  4. Sun and Shade leaves, SIF, and Photosynthetic Capacity

    Science.gov (United States)

    Berry, J. A.; Badgley, G.

    2016-12-01

    Recent advances in retrieval of solar induced chlorophyll fluorescence (SIF) have opened up new possibilities for remote sensing of canopy physiology and structure. To date most of the emphasis has been placed on SIF as an indicator of stress and photosynthetic capacity. However, it is clear that canopy structure can also have an influence. To this point, simulations of SIF in land surface models tend to under predict observed variation in SIF. Also, large, systematic differences in SIF from different canopy types seem to correlate well with the photosynthetic capacity of these canopies. SIF emissions from pampered crops can be several-fold that from evergreen, needle-leaf forests. Yet, these may have similar vegetation indices and absorb a similar fraction of incident PAR. SIF photons produced in a conifer canopy do have a lower probability of escaping its dense, clumped foliage. However, this does not explain the correlated differences in photosynthetic rate and SIF. It is useful, in this regard, to consider the separate contributions of sun and shade leaves to the SIF emitted by a canopy. Sun leaves tend to be displayed to intercept the direct solar beam, and these highly illuminated leaves are often visible from above the canopy. Sun leaves produce more SIF and a large fraction of it escapes. Therefore, the intensity of SIF may be a sensitive indicator of the partitioning of absorbed PAR to sun and shade leaves. Many models account tor the different photosynthetic capacity of sun and shade leaves in calculating canopy responses. However, the fraction of leaves in each category is usually parameterized by an assumed leaf angle distribution (e.g. spherical). In reality, the sun/shade fraction can vary over a wide range, and it has been difficult to measure. SIF and possibly near-IR reflectance of canopies can be used to specify this key parameter with obvious importance to understanding photosynthetic rate.

  5. Atmospheric transmittance model for photosynthetically active radiation

    International Nuclear Information System (INIS)

    Paulescu, Marius; Stefu, Nicoleta; Gravila, Paul; Paulescu, Eugenia; Boata, Remus; Pacurar, Angel; Mares, Oana; Pop, Nicolina; Calinoiu, Delia

    2013-01-01

    A parametric model of the atmospheric transmittance in the PAR band is presented. The model can be straightforwardly applied for calculating the beam, diffuse and global components of the PAR solar irradiance. The required inputs are: air pressure, ozone, water vapor and nitrogen dioxide column content, Ångström's turbidity coefficient and single scattering albedo. Comparison with other models and ground measured data shows a reasonable level of accuracy for this model, making it suitable for practical applications. From the computational point of view the calculus is condensed into simple algebra which is a noticeable advantage. For users interested in speed-intensive computation of the effective PAR solar irradiance, a PC program based on the parametric equations along with a user guide are available online at http://solar.physics.uvt.ro/srms

  6. Deriving C4 photosynthetic parameters from combined gas exchange and chlorophyll fluorescence using an Excel tool: theory and practice.

    Science.gov (United States)

    Bellasio, Chandra; Beerling, David J; Griffiths, Howard

    2016-06-01

    The higher photosynthetic potential of C4 plants has led to extensive research over the past 50 years, including C4 -dominated natural biomes, crops such as maize, or for evaluating the transfer of C4 traits into C3 lineages. Photosynthetic gas exchange can be measured in air or in a 2% Oxygen mixture using readily available commercial gas exchange and modulated PSII fluorescence systems. Interpretation of these data, however, requires an understanding (or the development) of various modelling approaches, which limit the use by non-specialists. In this paper we present an accessible summary of the theory behind the analysis and derivation of C4 photosynthetic parameters, and provide a freely available Excel Fitting Tool (EFT), making rigorous C4 data analysis accessible to a broader audience. Outputs include those defining C4 photochemical and biochemical efficiency, the rate of photorespiration, bundle sheath conductance to CO2 diffusion and the in vivo biochemical constants for PEP carboxylase. The EFT compares several methodological variants proposed by different investigators, allowing users to choose the level of complexity required to interpret data. We provide a complete analysis of gas exchange data on maize (as a model C4 organism and key global crop) to illustrate the approaches, their analysis and interpretation. © 2015 John Wiley & Sons Ltd. © 2016 John Wiley & Sons Ltd.

  7. Photoprotection Conferred by Changes in Photosynthetic Protein Levels and Organization during Dehydration of a Homoiochlorophyllous Resurrection Plant1

    Science.gov (United States)

    Charuvi, Dana; Nevo, Reinat; Shimoni, Eyal; Naveh, Leah; Zia, Ahmad; Adam, Zach; Farrant, Jill M.; Kirchhoff, Helmut; Reich, Ziv

    2015-01-01

    During desiccation, homoiochlorophyllous resurrection plants retain most of their photosynthetic apparatus, allowing them to resume photosynthetic activity quickly upon water availability. These plants rely on various mechanisms to prevent the formation of reactive oxygen species and/or protect their tissues from the damage they inflict. In this work, we addressed the issue of how homoiochlorophyllous resurrection plants deal with the problem of excessive excitation/electron pressures during dehydration using Craterostigma pumilum as a model plant. To investigate the alterations in the supramolecular organization of photosynthetic protein complexes, we examined cryoimmobilized, freeze-fractured leaf tissues using (cryo)scanning electron microscopy. These examinations revealed rearrangements of photosystem II (PSII) complexes, including a lowered density during moderate dehydration, consistent with a lower level of PSII proteins, as shown by biochemical analyses. The latter also showed a considerable decrease in the level of cytochrome f early during dehydration, suggesting that initial regulation of the inhibition of electron transport is achieved via the cytochrome b6f complex. Upon further dehydration, PSII complexes are observed to arrange into rows and semicrystalline arrays, which correlates with the significant accumulation of sucrose and the appearance of inverted hexagonal lipid phases within the membranes. As opposed to PSII and cytochrome f, the light-harvesting antenna complexes of PSII remain stable throughout the course of dehydration. Altogether, these results, along with photosynthetic activity measurements, suggest that the protection of retained photosynthetic components is achieved, at least in part, via the structural rearrangements of PSII and (likely) light-harvesting antenna complexes into a photochemically quenched state. PMID:25713340

  8. Long-term drought modifies the fundamental relationships between light exposure, leaf nitrogen content and photosynthetic capacity in leaves of the lychee tree (Litchi chinensis).

    Science.gov (United States)

    Damour, Gaëlle; Vandame, Marc; Urban, Laurent

    2008-09-08

    Drought has dramatic negative effects on plants' growth and crop productivity. Although some of the responses and underlying mechanisms are still poorly understood, there is increasing evidence that drought may have a negative effect on photosynthetic capacity. Biochemical models of leaf photosynthesis coupled with models of radiation transfer have been widely used in ecophysiological studies, and, more recently, in global change modeling. They are based on two fundamental relationships at the scale of the leaf: (i) nitrogen content-light exposure and (ii) photosynthetic capacity-nitrogen content. Although drought is expected to increase in many places across the world, such models are not adapted to drought conditions. More specifically, the effects of drought on the two fundamental relationships are not well documented. The objective of our study was to investigate the effects of a long-term drought imposed slowly on the nitrogen content and photosynthetic capacity of leaves similarly exposed to light, from 3-year-old lychee trees cv. Kwaï Mi. Leaf nitrogen and non-structural carbohydrate concentrations were measured along with gas exchanges and the light-saturated rate of photosynthetic electron transport (J(max)) after a 5.5-month-long period of drought. Leaf nitrogen content on a mass basis remained stable, while the leaf mass-to-area ratio (LMA) increased with increasing water stress. Consequently, the leaf nitrogen content on an area basis (N(a)) increased in a non-linear fashion. The starch content decreased, while the soluble sugar content increased. Stomata closed and net assimilation decreased to zero, while J(max) and the ratio J(max)/N(a) decreased with increasing water stress. The drought-associated decrease in photosynthetic capacity can be attributed to downregulation of photosynthetic electron transport and to reallocation of leaf nitrogen content. It is concluded that modeling photosynthesis in drought conditions will require, first, the modeling

  9. Controls on seasonal patterns of maximum ecosystem carbon uptake and canopy-scale photosynthetic light response: contributions from both temperature and photoperiod.

    Science.gov (United States)

    Stoy, Paul C; Trowbridge, Amy M; Bauerle, William L

    2014-02-01

    Most models of photosynthetic activity assume that temperature is the dominant control over physiological processes. Recent studies have found, however, that photoperiod is a better descriptor than temperature of the seasonal variability of photosynthetic physiology at the leaf scale. Incorporating photoperiodic control into global models consequently improves their representation of the seasonality and magnitude of atmospheric CO2 concentration. The role of photoperiod versus that of temperature in controlling the seasonal variability of photosynthetic function at the canopy scale remains unexplored. We quantified the seasonal variability of ecosystem-level light response curves using nearly 400 site years of eddy covariance data from over eighty Free Fair-Use sites in the FLUXNET database. Model parameters describing maximum canopy CO2 uptake and the initial slope of the light response curve peaked after peak temperature in about 2/3 of site years examined, emphasizing the important role of temperature in controlling seasonal photosynthetic function. Akaike's Information Criterion analyses indicated that photoperiod should be included in models of seasonal parameter variability in over 90% of the site years investigated here, demonstrating that photoperiod also plays an important role in controlling seasonal photosynthetic function. We also performed a Granger causality analysis on both gross ecosystem productivity (GEP) and GEP normalized by photosynthetic photon flux density (GEP n ). While photoperiod Granger-caused GEP and GEP n in 99 and 92% of all site years, respectively, air temperature Granger-caused GEP in a mere 32% of site years but Granger-caused GEP n in 81% of all site years. Results demonstrate that incorporating photoperiod may be a logical step toward improving models of ecosystem carbon uptake, but not at the expense of including enzyme kinetic-based temperature constraints on canopy-scale photosynthesis.

  10. Effects of shading on the photosynthetic characteristics and mesophyll cell ultrastructure of summer maize.

    Science.gov (United States)

    Ren, Baizhao; Cui, Haiyan; Camberato, James J; Dong, Shuting; Liu, Peng; Zhao, Bin; Zhang, Jiwang

    2016-08-01

    A field experiment was conducted to study the effects of shading on the photosynthetic characteristics and mesophyll cell ultrastructure of two summer maize hybrids Denghai605 (DH605) and Zhengdan958 (ZD958). The ambient sunlight treatment was used as control (CK) and shading treatments (40 % of ambient sunlight) were applied at different growth stages from silking (R1) to physiological maturity (R6) (S1), from the sixth leaf stage (V6) to R1 (S2), and from seeding to R6 (S3), respectively. The net photosynthetic rate (P n) was significantly decreased after shading. The greatest reduction of P n was found at S3 treatment, followed by S1 and S2 treatments. P n of S3 was decreased by 59 and 48 % for DH605, and 39 and 43 % for ZD958 at tasseling and milk-ripe stages, respectively, compared to that of CK. Additionally, leaf area index (LAI) and chlorophyll content decreased after shading. In terms of mesophyll cell ultrastructure, chloroplast configuration of mesophyll cells dispersed, and part of chloroplast swelled and became circular. Meanwhile, the major characteristics of chloroplasts showed poorly developed thylakoid structure at the early growth stage, blurry lamellar structure, loose grana, and a large gap between slices and warping granum. Then, plasmolysis occurred in mesophyll cells and the endomembrane system was destroyed, which resulted in the dissolution of cell membrane, karyotheca, mitochondria, and some membrane structures. The damaged mesophyll cell ultrastructure led to the decrease of photosynthetic capacity, and thus resulted in significant yield reduction by 45, 11, and 84 % in S1, S2, and S3 treatments, respectively, compared to that of CK.

  11. Genotypic variation in transpiration efficiency due to differences in photosynthetic capacity among sugarcane-related clones.

    Science.gov (United States)

    Li, Chunjia; Jackson, Phillip; Lu, Xin; Xu, Chaohua; Cai, Qing; Basnayake, Jayapathi; Lakshmanan, Prakash; Ghannoum, Oula; Fan, Yuanhong

    2017-04-01

    Sugarcane, derived from the hybridization of Saccharum officinarum×Saccharum spontaneum, is a vegetative crop in which the final yield is highly driven by culm biomass production. Cane yield under irrigated or rain-fed conditions could be improved by developing genotypes with leaves that have high intrinsic transpiration efficiency, TEi (CO2 assimilation/stomatal conductance), provided this is not offset by negative impacts from reduced conductance and growth rates. This study was conducted to partition genotypic variation in TEi among a sample of diverse clones from the Chinese collection of sugarcane-related germplasm into that due to variation in stomatal conductance versus that due to variation in photosynthetic capacity. A secondary goal was to define protocols for optimized larger-scale screening of germplasm collections. Genotypic variation in TEi was attributed to significant variation in both stomatal and photosynthetic components. A number of genotypes were found to possess high TEi as a result of high photosynthetic capacity. This trait combination is expected to be of significant breeding value. It was determined that a small number of observations (16) is sufficient for efficiently screening TEi in larger populations of sugarcane genotypes The research methodology and results reported are encouraging in supporting a larger-scale screening and introgression of high transpiration efficiency in sugarcane breeding. However, further research is required to quantify narrow sense heritability as well as the leaf-to-field translational potential of genotypic variation in transpiration efficiency-related traits observed in this study. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  12. Adults with an epilepsy history fare significantly worse on positive mental and physical health than adults with other common chronic conditions-Estimates from the 2010 National Health Interview Survey and Patient Reported Outcome Measurement System (PROMIS) Global Health Scale.

    Science.gov (United States)

    Kobau, Rosemarie; Cui, Wanjun; Zack, Matthew M

    2017-07-01

    Healthy People 2020, a national health promotion initiative, calls for increasing the proportion of U.S. adults who self-report good or better health. The Patient-Reported Outcomes Measurement Information System (PROMIS) Global Health Scale (GHS) was identified as a reliable and valid set of items of self-reported physical and mental health to monitor these two domains across the decade. The purpose of this study was to examine the percentage of adults with an epilepsy history who met the Healthy People 2020 target for self-reported good or better health and to compare these percentages to adults with history of other common chronic conditions. Using the 2010 National Health Interview Survey, we compared and estimated the age-standardized prevalence of reporting good or better physical and mental health among adults with five selected chronic conditions including epilepsy, diabetes, heart disease, cancer, and hypertension. We examined response patterns for physical and mental health scale among adults with these five conditions. The percentages of adults with epilepsy who reported good or better physical health (52%) or mental health (54%) were significantly below the Healthy People 2020 target estimate of 80% for both outcomes. Significantly smaller percentages of adults with an epilepsy history reported good or better physical health than adults with heart disease, cancer, or hypertension. Significantly smaller percentages of adults with an epilepsy history reported good or better mental health than adults with all other four conditions. Health and social service providers can implement and enhance existing evidence-based clinical interventions and public health programs and strategies shown to improve outcomes in epilepsy. These estimates can be used to assess improvements in the Healthy People 2020 Health-Related Quality of Life and Well-Being Objective throughout the decade. Published by Elsevier Inc.

  13. Scattering of ultraviolet and photosynthetically active radiation by Sorghum bicolor: influence of epicuticular wax

    International Nuclear Information System (INIS)

    Grant, R.H.; Jenks, M.A.; Rich, P.J.; Peters, P.J.; Ashworth, E.N.

    1995-01-01

    Near-isogenic mutants of Sorghum bicolor with genetic alterations affecting epicuticular wax (EW) structure but having similar canopy architecture provided a model system to examine the influence of EW on plant radiation scattering. Differences in canopies with two different sheath EW amounts showed differences in angular reflectance and transmittance. The differences varied with waveband of radiation. Canopy ultraviolet-B (UVB) and photosynthetically active radiation (PAR) backward reflectance in the principal solar plane were higher by wild-type plants (N-15) bearing reflective stalk EW filaments than mutant plants (bm-15) lacking stalk EW filaments. Between panicle emergence to anthesis the backward PAR reflectance increased more in the N-15 than bm-15 canopy. We suspect that the increase was a result of reflections from stalk facets emerging above the surface plane of the canopy foliage and exposing reflective EW. As panicles emerged above the foliage, canopy UVB and PAR forward reflectance by bm-15 increased while forward reflectance by N-15 decreased. The increased forward reflectance from bm-15 may be because of high specular reflectance from the microscopically smooth bm-15 stalk surfaces. Based on comparisons of probability distributions, significant differences in PAR and UVB canopy transmittance were detected between N-15 and bm-15. The median UVB transmittance was greater in the bm-15 canopy than the N-15 canopy, while the median PAR transmittance was the same for the two canopies. The greater transmittance in the N-15 canopy corresponded with lower EW load of the sheaths, but the difference between canopies was within the experimental error. Distinct influences of the stalk EW on canopy reflectance and transmittance were difficult to assess because of the relatively low proportion of surface area containing EW, the experimental errors associated with UVB irradiance field measurements. The optical properties of the S. bicolor canopy varied by waveband

  14. Flow of light energy in benthic photosynthetic microbial mats

    Energy Technology Data Exchange (ETDEWEB)

    Al-Najjar, Mohammad Ahmad A.

    2010-12-15

    The work in this thesis demonstrates the assessment of the energy budget inside microbial mat ecosystems, and the factors affecting light utilization efficiency. It presents the first balanced light energy budget for benthic microbial mat ecosystems, and shows how the budget and the spatial distribution of the local photosynthetic efficiencies within the euphotic zone depend on the absorbed irradiance (Jabs). The energy budget was dominated by heat dissipation on the expense of photosynthesis. The maximum efficiency of photosynthesis was at light limiting conditions When comparing three different marine benthic photosynthetic ecosystems (originated from Abu-Dhabi, Arctic, and Exmouth Gulf in Western Australia), differences in the efficiencies were calculated. The results demonstrated that the maximum efficiency depended on mat characteristics affecting light absorption and scattering; such as, photopigments ratio and distribution, and the structural organization of the photosynthetic organisms relative to other absorbing components of the ecosystem (i.e., EPS, mineral particles, detritus, etc.). The maximum efficiency decreased with increasing light penetration depth, and increased with increasing the accessory pigments (phycocyanin and fucoxanthin)/chlorophyll ratio. Spatial heterogeneity in photosynthetic efficiency, pigment distribution, as well as light acclimation in microbial mats originating from different geographical locations was investigated. We used a combined pigment imaging approach (variable chlorophyll fluorescence and hyperspectral imaging), and fingerprinting approach. For each mat, the photosynthetic activity was proportional to the local pigment concentration in the photic zone, but not for the deeper layers and between different mats. In each mat, yield of PSII and E1/2 (light acclimation) generally decreased in parallel with depth, but the gradients in both parameters varied greatly between samples. This mismatch between pigments concentration

  15. Canopy position affects photosynthetic adjustments to long-term elevated CO{sub 2} concentration (FACE) in aging needles in a mature Pinus taeda forest

    Energy Technology Data Exchange (ETDEWEB)

    Crous, K. Y.; Ellsworth, D. S. [University of Michigan, School of Natural Resources and Environment, Ann Arbor, MI (United States)

    2004-09-01

    Results of an assessment of the long-term effects of exposure to elevated carbon dioxide in free-air enrichment (FACE) on two age classes of pine needles in the upper and lower canopy of a pine forest in North Carolina are discussed. The observations were made during the second through sixth year of exposure. A significant response was observed in 60 per cent of all age classes and canopy locations. Evidence of concurrent down-regulation of Rubisco and electron transport capacity in upper canopy sunlit leaves was noted beyond the sixth year. No such effect was seen in the lower canopy. Carboxylation capacity and electron transport capacity in the upper canopy was down-regulated by 17-20 per cent in one year-old needles, but this was significant across sampling years only for electron transport capacity. It is suggested that a reduction in photosynthetic capacity in aging conifer needles at the canopy top may have significant consequences for canopy carbon balance and global carbon sinks because a major proportion of the annual carbon balance of these conifers is contributed by one-year old sunlit needles. 45 refs., 3 tabs., 4 figs.

  16. Spring photosynthetic recovery of boreal Norway spruce under conditions of elevated [CO(2)] and air temperature.

    Science.gov (United States)

    Wallin, Göran; Hall, Marianne; Slaney, Michelle; Räntfors, Mats; Medhurst, Jane; Linder, Sune

    2013-11-01

    Accumulated carbon uptake, apparent quantum yield (AQY) and light-saturated net CO2 assimilation (Asat) were used to assess the responses of photosynthesis to environmental conditions during spring for three consecutive years. Whole-tree chambers were used to expose 40-year-old field-grown Norway spruce trees in northern Sweden to an elevated atmospheric CO2 concentration, [CO2], of 700 μmol CO2 mol(-1) (CE) and an air temperature (T) between 2.8 and 5.6 °C above ambient T (TE), during summer and winter. Net shoot CO2 exchange (Anet) was measured continuously on 1-year-old shoots and was used to calculate the accumulated carbon uptake and daily Asat and AQY. The accumulated carbon uptake, from 1 March to 30 June, was stimulated by 33, 44 and 61% when trees were exposed to CE, TE, and CE and TE combined, respectively. Air temperature strongly influenced the timing and extent of photosynthetic recovery expressed as AQY and Asat during the spring. Under elevated T (TE), the recovery of AQY and Asat commenced ∼10 days earlier and the activity of these parameters was significantly higher throughout the recovery period. In the absence of frost events, the photosynthetic recovery period was less than a week. However, frost events during spring slowed recovery so that full recovery could take up to 60 days to complete. Elevated [CO2] stimulated AQY and Asat on average by ∼10 and ∼50%, respectively, throughout the recovery period, but had minimal or no effect on the onset and length of the photosynthetic recovery period during the spring. However, AQY, Asat and Anet all recovered at significantly higher T (average +2.2 °C) in TE than in TA, possibly caused by acclimation or by shorter days and lower light levels during the early part of the recovery in TE compared with TA. The results suggest that predicted future climate changes will cause prominent stimulation of photosynthetic CO2 uptake in boreal Norway spruce forest during spring, mainly caused by elevated T

  17. Photosynthetic Characteristics and Chloroplast Ultrastructure of Summer Maize Response to Different Nitrogen Supplies.

    Science.gov (United States)

    Liu, Zheng; Gao, Jia; Gao, Fei; Liu, Peng; Zhao, Bin; Zhang, Jiwang

    2018-01-01

    Maize ( Zea mays L.) is the important crop over the world. Nitrogen (N) as necessary element affects photosynthetic characteristics and grain yield of summer maize. In this study, N0 (0 kg N ha -1 ), N1 (129 kg N ha -1 ), N2 (185 kg N ha -1 ), and N3 (300 kg N ha -1 ) was conducted using hybrid 'ZhengDan958' at Dawenkou research field (36°11'N, 117°06'E, 178 m altitude) in the North China Plain to explore the effects of N rate on photosynthetic characteristics and chloroplast ultrastructure. Gas exchange parameters, chlorophyll fluorescence parameters, leaf area index (LAI), chlorophyll SPAD value, chloroplast ultrastructure, dry matter weight and grain yield were measured. At physiological maturity stage, dry matter weight and grain yield of N2 increased by 33-52% ( P ≤ 0.05) and 6-32% ( P ≤ 0.05), respectively, compared with other treatments. During the growing from silking (R1) to milk (R3) stage, LAI of N0 and N1 were 35-38% ( P ≤ 0.05) and 9-23% ( P ≤ 0.05) less than that of N2, respectively. Chlorophyll SPAD value of N0 and N1 were 13-22% ( P ≤ 0.05) and 5-11% ( P ≤ 0.05) lower than that of N2. There was no significant difference in LAI and chlorophyll SPAD value between N2 and N3 during the period from R1 to R3 ( P > 0.05). The net photosynthetic rate ( P n ), maximal quantum efficiency of PSII ( F v / F m ) and quantum efficiency of PSII (Φ PSII ) were higher with the increase of N rate up to N2 ( P ≤ 0.05), and those of N3 were significantly less than N2 ( P ≤ 0.05). In compared with N2, the chloroplast configuration of N0 and N1 became elliptical, almost circular or irregular. The membrane of chloroplast and thylakoid resolved with growing stage, and the number of chloroplast per cell and lamellae per grana decreased under N0 and N1 treatment ( P ≤ 0.05). Under N0 and N1 treatments, summer maize had more negative photosynthetic characteristics. The more number of osmium granule and vesicle and the larger gap between lamellae were

  18. Photosynthetic Characteristics and Chloroplast Ultrastructure of Summer Maize Response to Different Nitrogen Supplies

    Directory of Open Access Journals (Sweden)

    Zheng Liu

    2018-05-01

    Full Text Available Maize (Zea mays L. is the important crop over the world. Nitrogen (N as necessary element affects photosynthetic characteristics and grain yield of summer maize. In this study, N0 (0 kg N ha-1, N1 (129 kg N ha-1, N2 (185 kg N ha-1, and N3 (300 kg N ha-1 was conducted using hybrid ‘ZhengDan958’ at Dawenkou research field (36°11′N, 117°06′E, 178 m altitude in the North China Plain to explore the effects of N rate on photosynthetic characteristics and chloroplast ultrastructure. Gas exchange parameters, chlorophyll fluorescence parameters, leaf area index (LAI, chlorophyll SPAD value, chloroplast ultrastructure, dry matter weight and grain yield were measured. At physiological maturity stage, dry matter weight and grain yield of N2 increased by 33–52% (P ≤ 0.05 and 6–32% (P ≤ 0.05, respectively, compared with other treatments. During the growing from silking (R1 to milk (R3 stage, LAI of N0 and N1 were 35–38% (P ≤ 0.05 and 9–23% (P ≤ 0.05 less than that of N2, respectively. Chlorophyll SPAD value of N0 and N1 were 13–22% (P ≤ 0.05 and 5–11% (P ≤ 0.05 lower than that of N2. There was no significant difference in LAI and chlorophyll SPAD value between N2 and N3 during the period from R1 to R3 (P > 0.05. The net photosynthetic rate (Pn, maximal quantum efficiency of PSII (Fv/Fm and quantum efficiency of PSII (ΦPSII were higher with the increase of N rate up to N2 (P ≤ 0.05, and those of N3 were significantly less than N2 (P ≤ 0.05. In compared with N2, the chloroplast configuration of N0 and N1 became elliptical, almost circular or irregular. The membrane of chloroplast and thylakoid resolved with growing stage, and the number of chloroplast per cell and lamellae per grana decreased under N0 and N1 treatment (P ≤ 0.05. Under N0 and N1 treatments, summer maize had more negative photosynthetic characteristics. The more number of osmium granule and vesicle and the larger gap between lamellae were shown in N3

  19. Apparatus and method for measuring single cell and sub-cellular photosynthetic efficiency

    Science.gov (United States)

    Davis, Ryan Wesley; Singh, Seema; Wu, Huawen

    2013-07-09

    Devices for measuring single cell changes in photosynthetic efficiency in algal aquaculture are disclosed that include a combination of modulated LED trans-illumination of different intensities with synchronized through objective laser illumination and confocal detection. Synchronization and intensity modulation of a dual illumination scheme were provided using a custom microcontroller for a laser beam block and constant current LED driver. Therefore, single whole cell photosynthetic efficiency, and subcellular (diffraction limited) photosynthetic efficiency measurement modes are permitted. Wide field rapid light scanning actinic illumination is provided for both by an intensity modulated 470 nm LED. For the whole cell photosynthetic efficiency measurement, the same LED provides saturating pulses for generating photosynthetic induction curves. For the subcellular photosynthetic efficiency measurement, a switched through objective 488 nm laser provides saturating pulses for generating photosynthetic induction curves. A second near IR LED is employed to generate dark adapted states in the system under study.

  20. Non-cooperative immobilization of residual water bound in lyophilized photosynthetic lamellae.

    Science.gov (United States)

    Harańczyk, Hubert; Baran, Ewelina; Nowak, Piotr; Florek-Wojciechowska, Małgorzata; Leja, Anna; Zalitacz, Dorota; Strzałka, Kazimierz

    2015-12-01

    This study applied 1H-NMR in time and in frequency domain measurements to monitor the changes that occur in bound water dynamics at decreased temperature and with increased hydration level in lyophilizates of native wheat photosynthetic lamellae and in photosynthetic lamellae reconstituted from lyophilizate. Proton relaxometry (measured as free induction decay = FID) distinguishes a Gaussian component S within the NMR signal (o). This comes from protons of the solid matrix of the lamellae and consists of (i) an exponentially decaying contribution L1 from mobile membrane protons, presumably from lipids, and from water that is tightly bound to the membrane surface and thus restricted in mobility; and (ii) an exponentially decaying component L2 from more mobile, loosely bound water pool. Both proton relaxometry data and proton spectroscopy show that dry lyophilizate incubated in dry air, i.e., at a relative humidity (p/p0) of 0% reveals a relatively high hydration level. The observed liquid signal most likely originates from mobile membrane protons and a tightly bound water fraction that is sealed in pores of dry lyophilizate and thus restricted in mobility. The estimations suggest that the amount of sealed water does not exceed the value characteristic for the main hydration shell of a phospholipid. Proton spectra collected for dry lyophilizate of photosynthetic lamellae show a continuous decrease in the liquid signal component without a distinct freezing transition when it is cooled down to -60ºC, which is significantly lower than the homogeneous ice nucleation temperature [Bronshteyn, V.L. et al. Biophys. J. 65 (1993) 1853].

  1. Thermoluminescence as a complementary technique for the toxicological evaluation of chemicals in photosynthetic organisms

    Energy Technology Data Exchange (ETDEWEB)

    Repetto, Guillermo, E-mail: grepkuh@upo.es [Departamento de Biología Molecular e Ingeniería Bioquímica, Área de Toxicología, Universidad Pablo de Olavide, Carretera de Utrera km. 1, 41013 Seville (Spain); Zurita, Jorge L. [Departamento de Biología Molecular e Ingeniería Bioquímica, Área de Toxicología, Universidad Pablo de Olavide, Carretera de Utrera km. 1, 41013 Seville (Spain); Roncel, Mercedes; Ortega, José M. [Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-CSIC, Américo Vespucio 49, 41092 Seville (Spain)

    2015-01-15

    Highlights: • There are very few toxicological applications of thermoluminescence. • It is a luminescence emission induced by heating the sample in the dark. • It is useful for study the photosystem II function and the level of lipid peroxidation. - Abstract: Thermoluminescence is a simple technique very useful for studying electron transfer reactions on photosystem II (standard thermoluminescence) or the level of lipid peroxidation in membranes (high temperature thermoluminescence) in photosynthetic organisms. Both techniques were used to investigate the effects produced on Chlorella vulgaris cells by six compounds: the chemical intermediates bromobenzene and diethanolamine, the antioxidant propyl gallate, the semiconductor indium nitrate, the pesticide sodium monofluoroacetate and the antimalarial drug chloroquine. Electron transfer activity of the photosystem II significantly decreased after the exposure of Chlorella cells to all the six chemicals used. Lipid peroxidation was slightly decreased by the antioxidant propyl gallate, not changed by indium nitrate and very potently stimulated by diethanolamine, chloroquine, sodium monofluoroacetate and bromobenzene. For five of the chemicals studied (not bromobenzene) there is a very good correlation between the cytotoxic effects in Chlorella cells measured by the algal growth inhibition test, and the inhibition of photosystem II activity. The results suggest that one very important effect of these chemicals in Chlorella cells is the inhibition of photosynthetic metabolism by the blocking of photosystem II functionality. In the case of sodium monofluoroacetate, diethanolamine and chloroquine this inhibition seems to be related with the induction of high level of lipid peroxidation in cells that may alter the stability of photosystem II. The results obtained by both techniques supply information that can be used as a supplement to the growth inhibition test and allows a more complete assessment of the effects of

  2. Exploring photosynthesis evolution by comparative analysis of metabolic networks between chloroplasts and photosynthetic bacteria

    Directory of Open Access Journals (Sweden)

    Hou Jing

    2006-04-01

    Full Text Available Abstract Background Chloroplasts descended from cyanobacteria and have a drastically reduced genome following an endosymbiotic event. Many genes of the ancestral cyanobacterial genome have been transferred to the plant nuclear genome by horizontal gene transfer. However, a selective set of metabolism pathways is maintained in chloroplasts using both chloroplast genome encoded and nuclear genome encoded enzymes. As an organelle specialized for carrying out photosynthesis, does the chloroplast metabolic network have properties adapted for higher efficiency of photosynthesis? We compared metabolic network properties of chloroplasts and prokaryotic photosynthetic organisms, mostly cyanobacteria, based on metabolic maps derived from genome data to identify features of chloroplast network properties that are different from cyanobacteria and to analyze possible functional significance of those features. Results The properties of the entire metabolic network and the sub-network that consists of reactions directly connected to the Calvin Cycle have been analyzed using hypergraph representation. Results showed that the whole metabolic networks in chloroplast and cyanobacteria both possess small-world network properties. Although the number of compounds and reactions in chloroplasts is less than that in cyanobacteria, the chloroplast's metabolic network has longer average path length, a larger diameter, and is Calvin Cycle -centered, indicating an overall less-dense network structure with specific and local high density areas in chloroplasts. Moreover, chloroplast metabolic network exhibits a better modular organization than cyanobacterial ones. Enzymes involved in the same metabolic processes tend to cluster into the same module in chloroplasts. Conclusion In summary, the differences in metabolic network properties may reflect the evolutionary changes during endosymbiosis that led to the improvement of the photosynthesis efficiency in higher plants. Our

  3. Thermoluminescence as a complementary technique for the toxicological evaluation of chemicals in photosynthetic organisms

    International Nuclear Information System (INIS)

    Repetto, Guillermo; Zurita, Jorge L.; Roncel, Mercedes; Ortega, José M.

    2015-01-01

    Highlights: • There are very few toxicological applications of thermoluminescence. • It is a luminescence emission induced by heating the sample in the dark. • It is useful for study the photosystem II function and the level of lipid peroxidation. - Abstract: Thermoluminescence is a simple technique very useful for studying electron transfer reactions on photosystem II (standard thermoluminescence) or the level of lipid peroxidation in membranes (high temperature thermoluminescence) in photosynthetic organisms. Both techniques were used to investigate the effects produced on Chlorella vulgaris cells by six compounds: the chemical intermediates bromobenzene and diethanolamine, the antioxidant propyl gallate, the semiconductor indium nitrate, the pesticide sodium monofluoroacetate and the antimalarial drug chloroquine. Electron transfer activity of the photosystem II significantly decreased after the exposure of Chlorella cells to all the six chemicals used. Lipid peroxidation was slightly decreased by the antioxidant propyl gallate, not changed by indium nitrate and very potently stimulated by diethanolamine, chloroquine, sodium monofluoroacetate and bromobenzene. For five of the chemicals studied (not bromobenzene) there is a very good correlation between the cytotoxic effects in Chlorella cells measured by the algal growth inhibition test, and the inhibition of photosystem II activity. The results suggest that one very important effect of these chemicals in Chlorella cells is the inhibition of photosynthetic metabolism by the blocking of photosystem II functionality. In the case of sodium monofluoroacetate, diethanolamine and chloroquine this inhibition seems to be related with the induction of high level of lipid peroxidation in cells that may alter the stability of photosystem II. The results obtained by both techniques supply information that can be used as a supplement to the growth inhibition test and allows a more complete assessment of the effects of

  4. A theoretical approach to photosynthetically active radiation silicon sensor

    International Nuclear Information System (INIS)

    Tamasi, M.J.L.; Martínez Bogado, M.G.

    2013-01-01

    This paper presents a theoretical approach for the development of low cost radiometers to measure photosynthetically active radiation (PAR). Two alternatives are considered: a) glass optical filters attached to a silicon sensor, and b) dielectric coating on a silicon sensor. The devices proposed are based on radiometers previously developed by the Argentine National Atomic Energy Commission. The objective of this work is to adapt these low cost radiometers to construct reliable instruments for measuring PAR. The transmittance of optical filters and sensor response have been analyzed for different dielectric materials, number of layers deposited, and incidence angles. Uncertainties in thickness of layer deposition were evaluated. - Highlights: • Design of radiometers to measure photosynthetically active radiation • The study has used a filter and a Si sensor to modify spectral response. • Dielectric multilayers on glass and silicon sensor • Spectral response related to different incidence angles, materials and spectra

  5. Photosynthetic planulae and planktonic hydroids: contrasting strategies of propagule survival

    Directory of Open Access Journals (Sweden)

    Patrizia Pagliara

    2000-12-01

    Full Text Available Settlement delays can be important to prevent propagule waste when proper settling substrates are not immediately available. Under laboratory conditions, the planulae of Clytia viridicans underwent two alternative developmental patterns. Some settled on the bottom, forming a hydranth-gonotheca complex that produced up to four medusae and later either degenerated or gave rise to a hydroid colony. Other planulae settled right below the air-water interface, forming floating colonies that eventually fell to the bottom and settled. Halecium nanum released planulae with a rich population of symbiotic zooxanthellae that survived into a rearing jar for three months. After a long period of apparent quiescence (possibly fuelled by photosynthetic activities of zooxanthellae the planulae produced new colonies. Both photosynthetic planulae and settlement at the interface air-water allow a delay in the passage from a planktonic to a fully functional benthic life.

  6. Photosynthetic Energy Transfer at the Quantum/Classical Border.

    Science.gov (United States)

    Keren, Nir; Paltiel, Yossi

    2018-06-01

    Quantum mechanics diverges from the classical description of our world when very small scales or very fast processes are involved. Unlike classical mechanics, quantum effects cannot be easily related to our everyday experience and are often counterintuitive to us. Nevertheless, the dimensions and time scales of the photosynthetic energy transfer processes puts them close to the quantum/classical border, bringing them into the range of measurable quantum effects. Here we review recent advances in the field and suggest that photosynthetic processes can take advantage of the sensitivity of quantum effects to the environmental 'noise' as means of tuning exciton energy transfer efficiency. If true, this design principle could be a base for 'nontrivial' coherent wave property nano-devices. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Non-photosynthetic plastids as hosts for metabolic engineering

    DEFF Research Database (Denmark)

    Mellor, Silas Busck; Behrendorff, James Bruce Yarnton H; Nielsen, Agnieszka Janina Zygadlo

    2018-01-01

    Using plants as hosts for production of complex, high-value compounds and therapeutic proteins has gained increasing momentum over the past decade. Recent advances in metabolic engineering techniques using synthetic biology have set the stage for production yields to become economically attractive......, but more refined design strategies are required to increase product yields without compromising development and growth of the host system. The ability of plant cells to differentiate into various tissues in combination with a high level of cellular compartmentalization represents so far the most...... in green tissues, have proven to be suitable for high yield protein and bio-compound production. Unfortunately, chloroplast manipulation often affects photosynthetic efficiency and therefore plant fitness. In this respect, plastids of non-photosynthetic tissues, which have focused metabolisms for synthesis...

  8. Influence of thermal light correlations on photosynthetic structures

    Science.gov (United States)

    de Mendoza, Adriana; Manrique, Pedro; Caycedo-Soler, Felipe; Johnson, Neil F.; Rodríguez, Ferney J.; Quiroga, Luis

    2014-03-01

    The thermal light from the sun is characterized by both classical and quantum mechanical correlations. These correlations have left a fingerprint on the natural harvesting structures developed through five billion years of evolutionary pressure, specially in photosynthetic organisms. In this work, based upon previous extensive studies of spatio-temporal correlations of light fields, we hypothesize that structures involving photosensitive pigments like those present in purple bacteria vesicles emerge as an evolutionary response to the different properties of incident light. By using burstiness and memory as measures that quantify higher moments of the photon arrival statistics, we generate photon-time traces. They are used to simulate absorption on detectors spatially extended over regions comparable to these light fields coherence length. Finally, we provide some insights into the connection between these photo-statistical features with the photosynthetic membrane architecture and the lights' spatial correlation. Facultad de Ciencias Uniandes.

  9. BOREAS TE-9 NSA Photosynthetic Capacity and Foliage Nitrogen Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Dang, Qinglai; Margolis, Hank; Coyea, Marie

    2000-01-01

    The Boreal Ecosystem-Atmospheric Study (BOREAS) TE-9 (Terrestrial Ecology) team collected several data sets related to chemical and photosynthetic properties of leaves in boreal forest tree species. This data set describes the spatial and temporal relationship between foliage nitrogen concentration and photosynthetic capacity in the canopies of black spruce, jack pine, and aspen located within the Northern Study Area (NSA). The data were collected from June to September 1994 and are useful for modeling the vertical distribution of carbon fixation for different forest types in the boreal forest. The data are available in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  10. Advances in Metabolic Engineering of Cyanobacteria for Photosynthetic Biochemical Production

    OpenAIRE

    Lai, Martin C.; Lan, Ethan I.

    2015-01-01

    Engineering cyanobacteria into photosynthetic microbial cell factories for the production of biochemicals and biofuels is a promising approach toward sustainability. Cyanobacteria naturally grow on light and carbon dioxide, bypassing the need of fermentable plant biomass and arable land. By tapping into the central metabolism and rerouting carbon flux towards desirable compound production, cyanobacteria are engineered to directly convert CO2 into various chemicals. This review discusses the d...

  11. Microbiological Hydrogen Production by Anaerobic Fermentation and Photosynthetic Process

    International Nuclear Information System (INIS)

    Asada, Y.; Ohsawa, M.; Nagai, Y.; Fukatsu, M.; Ishimi, K.; Ichi-ishi, S.

    2009-01-01

    Hydrogen gas is a clean and renewable energy carrier. Microbiological hydrogen production from glucose or starch by combination used of an anaerobic fermenter and a photosynthetic bacterium, Rhodobacter spheroides RV was studied. In 1984, the co-culture of Clostridium butyricum and RV strain to convert glucose to hydrogen was demonstrated by Miyake et al. Recently, we studied anaerobic fermentation of starch by a thermophilic archaea. (Author)

  12. Isoprenoids emission in Stipa tenacissima L.: Photosynthetic control and the effect of UV light

    International Nuclear Information System (INIS)

    Guidolotti, Gabriele; Rey, Ana; Medori, Mauro; Calfapietra, Carlo

    2016-01-01

    Fluxes of CO_2 and isoprenoids were measured for the first time in Stipa tenacissima L (alfa grass), a perennial tussock grass dominant in the driest areas of Europe. In addition, we studied how those fluxes were influenced by environmental conditions, leaf ontogeny and UV radiation and compared emission rates in two contrasting seasons: summer when plants are mostly inactive and autumn, the growing season in this region. Leaf ontogeny significantly affected both photosynthesis and isoprenoids emission. Isoprene emission was positively correlated with photosynthesis, although a low isoprene emission was detected in brown leaves with a net carbon loss. Moreover, leaves with a significant lower photosynthesis emitted only monoterpenes, while at higher photosynthetic rates also isoprene was produced. Ambient UV radiation uncoupled photosynthesis and isoprene emission. It is speculated that alfa grass represent an exception from the general rules governing plant isoprenoid emitters. - Highlights: • Stipa tenacissima L. is a grass emitting either monoterpenes and isoprene. • The emission has reasonable rates even in senescent leaves. • Isoprene emission is positively correlated with CO_2 assimilation. • Ambient UV radiation uncouples photosynthesis and isoprene emission. • Leaves with lower photosynthetic rates emit only monoterpenes. - We proved for the first time that alfa grass emit both isoprene and monoterpene, and we provide some innovative aspects about the UV effect and the behavior of Stipa tenacissima.

  13. Herbicide effects on the growth and photosynthetic efficiency of Cassiopea maremetens.

    Science.gov (United States)

    Rowen, David J; Templeman, Michelle A; Kingsford, Michael J

    2017-09-01

    Herbicides from agricultural run-off have been measured in coastal systems of the Great Barrier Reef over many years. Non-target herbicide exposure, especially photosystem II herbicides has the potential to affect seagrasses and other marine species. The symbiotic benthic jellyfish Cassiopea maremetens is present in tropical/sub-tropical estuarine and marine environments. Jellyfish (n = 8 per treatment) were exposed to four separate concentrations of agricultural formulations of diuron or hexazinone to determine their sensitivity and potential for recovery to pulsed herbicide exposure. Jellyfish growth, symbiont photosynthetic activity and zooxanthellae density were analysed for herbicide-induced changes for 7 days followed by a 7 day recovery period. Both the jellyfish and endosymbiont were more sensitive to diuron than hexazinone. The 7-day EC 50 for jellyfish growth was 0.35 μg L -1 for Diuron and 17.5 μg L -1 for Hexazinone respectively. Diuron exposure caused a significant decrease (p diuron and hexazinone caused significant decreases in photosynthetic efficiency (effective quantum yield) in all treatment concentrations (0.1 μg L -1 and above) and this effect continued in the post-exposure period. As this species is frequently found in near-shore environments, they may be particularly vulnerable to herbicide run-off. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Photosynthetic Characteristics of Flag Leaves in Rice White Stripe Mutant 6001 During Senescence Process

    Directory of Open Access Journals (Sweden)

    Xiao-hui ZHEN

    2014-11-01

    Full Text Available Physiological, biochemical and electron microscopy analyses were used to investigate the photosynthetic performance of flag leaves in rice white stripe mutant 6001 during the senescence process. Results showed that the chlorophyll content at the heading and milk-ripe stages in rice mutant 6001 were about 34.78% and 3.00% less than those in wild type 6028, respectively. However, the chlorophyll content at the fully-ripe stage in rice mutant 6001 was higher than that in wild type 6028. At the heading stage, the net photosynthetic rate (Pn in rice mutant 6001 was lower than that in wild type 6028. Rice mutant 6001 also exhibited a significantly slower decrease rate of Pn than wild type 6028 during the senescence progress, especially at the later stage. Furthermore, Ca2+-ATPase, Mg2+-ATPase and photophosphorylation activities exhibited the similar trends as the Pn. During the senescence process, the 68 kDa polypeptide concentrations in the thylakoid membrane proteins exhibited a significant change, which was one of the critical factors that contributed to the observed change in photosynthesis. We also observed that the chloroplasts of rice mutant 6001 exhibited higher integrity than those of wild type 6028, and the chloroplast membrane of rice mutant 6001 disintegrated more slow during the senescence process. In general, rice mutant 6001 had a relatively slower senescence rate than wild type 6028, and exhibited anti-senescence properties.

  15. Bioaccumulation and effect of cadmium in the photosynthetic apparatus of Prosopis juliflora

    Directory of Open Access Journals (Sweden)

    Claudia Yared Michel-López

    2016-10-01

    Full Text Available In the present study Prosopis juliflora plants grown in hydroponics solution were exposed to 50,100 and 1000 μM CdCl2. The cadmium uptake, transport and toxicity on the photosynthetic activities in the plants were measured at 48 h after starting cadmium treatments. The results showed that the concentration of Cd2+ in P. juliflora tended to increase with addition of Cd2+ to hydroponics solution. However, the increase of Cd2+ in roots and leaves varied largely. In this sense, the accumulation of Cd2+ in P. juliflora roots increased significantly in proportion with the addition of this metal. In contrast a relatively low level of Cd2+ transportation index, and bioaccumulation factor were found in P. juliflora at 48 h after of treatments. On the other hand the maximum photochemical efficiency of photosystem II (Fv/Fm and the activity of photosystem II (Fv/Fo ratios in P. juliflora leaf treated with Cd2+ not showed significantly changes during the experiment. These results suggested that the photosynthetic apparatus of P. juliflora was not the primary target of the Cd2+ action. Further studies will be focused in understanding the participation of the root system in Prosopis plants with the rhizosphere activation and root adsorption to soil Cd2+ under natural conditions.

  16. Continuous cultivation of photosynthetic microorganisms: Approaches, applications and future trends.

    Science.gov (United States)

    Fernandes, Bruno D; Mota, Andre; Teixeira, Jose A; Vicente, Antonio A

    2015-11-01

    The possibility of using photosynthetic microorganisms, such as cyanobacteria and microalgae, for converting light and carbon dioxide into valuable biochemical products has raised the need for new cost-efficient processes ensuring a constant product quality. Food, feed, biofuels, cosmetics and pharmaceutics are among the sectors that can profit from the application of photosynthetic microorganisms. Biomass growth in a photobioreactor is a complex process influenced by multiple parameters, such as photosynthetic light capture and attenuation, nutrient uptake, photobioreactor hydrodynamics and gas-liquid mass transfer. In order to optimize productivity while keeping a standard product quality, a permanent control of the main cultivation parameters is necessary, where the continuous cultivation has shown to be the best option. However it is of utmost importance to recognize the singularity of continuous cultivation of cyanobacteria and microalgae due to their dependence on light availability and intensity. In this sense, this review provides comprehensive information on recent breakthroughs and possible future trends regarding technological and process improvements in continuous cultivation systems of microalgae and cyanobacteria, that will directly affect cost-effectiveness and product quality standardization. An overview of the various applications, techniques and equipment (with special emphasis on photobioreactors) in continuous cultivation of microalgae and cyanobacteria are presented. Additionally, mathematical modeling, feasibility, economics as well as the applicability of continuous cultivation into large-scale operation, are discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Quantum transport in the FMO photosynthetic light-harvesting complex.

    Science.gov (United States)

    Karafyllidis, Ioannis G

    2017-06-01

    The very high light-harvesting efficiency of natural photosynthetic systems in conjunction with recent experiments, which showed quantum-coherent energy transfer in photosynthetic complexes, raised questions regarding the presence of non-trivial quantum effects in photosynthesis. Grover quantum search, quantum walks, and entanglement have been investigated as possible effects that lead to this efficiency. Here we explain the near-unit photosynthetic efficiency without invoking non-trivial quantum effects. Instead, we use non-equilibrium Green's functions, a mesoscopic method used to study transport in nano-conductors to compute the transmission function of the Fenna-Matthews-Olson (FMO) complex using an experimentally derived exciton Hamiltonian. The chlorosome antenna and the reaction center play the role of input and output contacts, connected to the FMO complex. We show that there are two channels for which the transmission is almost unity. Our analysis also revealed a dephasing-driven regulation mechanism that maintains the efficiency in the presence of varying dephasing potentials.

  18. Photosynthetic Reaction Centres-from Basic Research to Application

    Directory of Open Access Journals (Sweden)

    László NAGY

    2010-06-01

    Full Text Available There is no doubt that studying the photosynthetic conversion of light into chemical energy is extremely important in many points of view; e.g., 1 technical-in order to improve the utilization of the solar energy; 2 food production-to improve the photosynthetic production of plants in agriculture; 3 ecology-keeping the primer production in ecosystems in the biosphere balanced, etc. In the photosynthetic reaction centre protein, RC, light energy is converted by a quantum yield of almost unity. There is no such a system designed by human which is able to do that. The RC purified from purple bacteria provides an extremely unique system for studying the requirements for high efficiency conversion of light into electrochemical energy. Thanks to the recent structural (e.g. crystallography (Nobel prize to Michel, Deisenhofer, Huber and functional (Nobel prize to Marcus results together with the works of molecular biology, computer- and electro-techniques, a wealth of information made a relatively clear picture about the kinetics, energetics and stabilization of electron transport within this protein that opens possibilities for new generation practical applications. In this paper we provide a short summary of fields in which the reaction centre protein can be important from practical points of view.

  19. Photovoltaic concepts inspired by coherence effects in photosynthetic systems

    KAUST Repository

    Bredas, Jean-Luc

    2016-12-20

    The past decade has seen rapid advances in our understanding of how coherent and vibronic phenomena in biological photosynthetic systems aid in the efficient transport of energy from light-harvesting antennas to photosynthetic reaction centres. Such coherence effects suggest strategies to increase transport lengths even in the presence of structural disorder. Here we explore how these principles could be exploited in making improved solar cells. We investigate in depth the case of organic materials, systems in which energy and charge transport stand to be improved by overcoming challenges that arise from the effects of static and dynamic disorder-structural and energetic-and from inherently strong electron-vibration couplings. We discuss how solar-cell device architectures can evolve to use coherence-exploiting materials, and we speculate as to the prospects for a coherent energy conversion system. We conclude with a survey of the impacts of coherence and bioinspiration on diverse solar-energy harvesting solutions, including artificial photosynthetic systems.

  20. DAILY BUDGETS OF PHOTOSYNTHETICALLY FIXED CARBON IN SYMBIOTIC ZOANTHIDS.

    Science.gov (United States)

    Steen, R Grant; Muscatine, L

    1984-10-01

    We tested the hypothesis that some zoanthids are able to meet a portion of their daily respiratory carbon requirement with photosynthetic carbon from symbiotic algal cells (= zooxanthellae). A daily budget was constructed for carbon (C) photosynthetically fixed by zooxanthellae of the Bermuda zoanthids Zoanthus sociatus and Palythoa variabilis. Zooxanthellae have an average net photosynthetic C fixation of 7.48 and 15.56 µgC·polyp -1 ·day -1 for Z. sociatus and P. variabilis respectively. The C-specific growth rate (µ c ) was 0.215·day -1 for Z. sociatus and 0.152·day -1 for P. variabilis. The specific growth rate (µ) of zooxanthellae in the zoanthids was measured to be 0.011 and 0.017·day -1 for Z. sociatus and P. variabilis zooxanthellae respectively. Z. sociatus zooxanthellae translocated 95.1% of the C assimilated in photosynthesis, while P. variabilis zooxanthellae translocated 88.8% of their fixed C. As the animal tissue of a polyp of Z. sociatus required 14.75 µgC·day -1 for respiration, and one of P. variabiis required 105.54 µgC·day -1 , the contribution of zooxanthellae to animal respiration (CZAR) was 48.2% for Z. sociatus and 13.1% for P. variabilis.

  1. Metabolic Engineering and Modeling of Metabolic Pathways to Improve Hydrogen Production by Photosynthetic Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Navid, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-12-19

    Rising energy demands and the imperative to reduce carbon dioxide (CO2) emissions are driving research on biofuels development. Hydrogen gas (H2) is one of the most promising biofuels and is seen as a future energy carrier by virtue of the fact that 1) it is renewable, 2) does not evolve the “greenhouse gas” CO2 in combustion, 3) liberates large amounts of energy per unit weight in combustion (having about 3 times the energy content of gasoline), and 4) is easily converted to electricity by fuel cells. Among the various bioenergy strategies, environmental groups and others say that the concept of the direct manufacture of alternative fuels, such as H2, by photosynthetic organisms is the only biofuel alternative without significant negative criticism [1]. Biological H2 production by photosynthetic microorganisms requires the use of a simple solar reactor such as a transparent closed box, with low energy requirements, and is considered as an attractive system to develop as a biocatalyst for H2 production [2]. Various purple bacteria including Rhodopseudomonas palustris, can utilize organic substrates as electron donors to produce H2 at the expense of solar energy. Because of the elimination of energy cost used for H2O oxidation and the prevention of the production of O2 that inhibits the H2-producing enzymes, the efficiency of light energy conversion to H2 by anoxygenic photosynthetic bacteria is in principle much higher than that by green algae or cyanobacteria, and is regarded as one of the most promising cultures for biological H2 production [3]. Here implemented a simple and relatively straightforward strategy for hydrogen production by photosynthetic microorganisms using sunlight, sulfur- or iron-based inorganic substrates, and CO2 as the feedstock. Carefully selected microorganisms with bioengineered beneficial

  2. A Meta-analysis of Plant Photosynthetic Traits and Water-use efficiency Responses to Drought

    Science.gov (United States)

    Zhang, J.

    2017-12-01

    decrease in the Pn and 72% of the decline in Tr. Nevertheless, the Gs did not show a significant linear correlation with WUE, it's a more complex relationship between them .Our study provides comprehensive information about the changes in plant photosynthetic traits and water use efficiency under drought.

  3. Global Positioning System : significant challenges in sustaining and upgrading widely used capabilities : report to the Subcommittee on National Security and Foreign Affairs, Committee on Oversight and Government Reform, House of Representatives.

    Science.gov (United States)

    2009-04-01

    The Global Positioning System (GPS), which provides positioning, navigation, and timing data to users worldwide, has become essential to U.S. national security and a key tool in an expanding array of public service and commercial applications at home...

  4. Comparison of Methods for Estimating Fractional Cover of Photosynthetic and Non-Photosynthetic Vegetation in the Otindag Sandy Land Using GF-1 Wide-Field View Data

    Directory of Open Access Journals (Sweden)

    Xiaosong Li

    2016-09-01

    Full Text Available Photosynthetic vegetation (PV and non-photosynthetic vegetation (NPV are important ground cover types for desertification monitoring and land management. Hyperspectral remote sensing has been proven effective for separating NPV from bare soil, but few studies determined fractional cover of PV (fpv and NPV (fnpv using multispectral information. The purpose of this study is to evaluate several spectral unmixing approaches for retrieval of fpv and fnpv in the Otindag Sandy Land using GF-1 wide-field view (WFV data. To deal with endmember variability, pixel-invariant (Spectral Mixture Analysis, SMA and pixel-variable (Multi-Endmember Spectral Mixture Analysis, MESMA, and Automated Monte Carlo Unmixing Analysis, AutoMCU endmember selection approaches were applied. Observed fractional cover data from 104 field sites were used for comparison. For fpv, all methods show statistically significant correlations with observed data, among which AutoMCU had the highest performance (R2 = 0.49, RMSE = 0.17, followed by MESMA (R2 = 0.48, RMSE = 0.21, and SMA (R2 = 0.47, RMSE = 0.27. For fnpv, MESMA had the lowest performance (R2 = 0.11, RMSE = 0.24 because of coupling effects of the NPV and bare soil endmembers, SMA overestimates fnpv (R2 = 0.41, RMSE = 0.20, but is significantly correlated with observed data, and AutoMCU provides the most accurate predictions of fnpv (R2 = 0.49, RMSE = 0.09. Thus, the AutoMCU approach is proven to be more effective than SMA and MESMA, and GF-1 WFV data are capable of distinguishing NPV from bare soil in the Otindag Sandy Land.

  5. Drought tolerance of selected bottle gourd [Lagenaria siceraria (Molina) Standl.] landraces assessed by leaf gas exchange and photosynthetic efficiency.

    Science.gov (United States)

    Mashilo, Jacob; Odindo, Alfred O; Shimelis, Hussein A; Musenge, Pearl; Tesfay, Samson Z; Magwaza, Lembe S

    2017-11-01

    Successful cultivation of bottle gourd in arid and semi-arid areas of sub-Saharan Africa and globally requires the identification of drought tolerant parents for developing superior genotypes with increased drought resistance. The objective of this study was to determine the level of drought tolerance among genetically diverse South African bottle gourd landraces based on leaf gas exchange and photosynthetic efficiency and identify promising genotypes for breeding. The responses of 12 bottle gourd landraces grown in glasshouse under non-stressed (NS) and drought-stressed (DS) conditions were studied. A significant genotype x water regime interaction was observed for gs, T, A, A/C i , IWUE, WUE ins , F m ', F v '/F m ', Ф PSII , qP, qN, ETR, ETR/A and AES indicating variability in response among the studied bottle gourd landraces under NS and DS conditions. Principal component analysis identified three principal components (PC's) under drought stress condition contributing to 82.9% of total variation among leaf gas exchange and chlorophyll fluorescence parameters measured. PC1 explained 36% of total variation contributed by gs, T, F 0 ', F m ', F v '/F m ' and qN, while PC2 explained 28% of the variation and highly correlated with A, A/C i , IWUE, WUE ins ETR/A and AES. PC3 explained 14% of total variation contributed by Ф PSII , qP and ETR. Principal biplot analysis allowed the identification of drought tolerant genotypes such as BG-27, BG-48, BG-58, BG-79, BG-70 and BG-78 which were grouped based on high gs, A, F m 'F v '/F m ', qN, ETR/A and AES under DS condition. The study suggests that the identified physiological traits could be useful indicators in the selection of bottle gourd genotypes for increased drought tolerance. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  6. Seeing green bacteria in a new light: genomics-enabled studies of the photosynthetic apparatus in green sulfur bacteria and filamentous anoxygenic phototrophic bacteria

    DEFF Research Database (Denmark)

    Frigaard, Niels-Ulrik; Bryant, Donald A

    2004-01-01

    Based upon their photosynthetic nature and the presence of a unique light-harvesting antenna structure, the chlorosome, the photosynthetic green bacteria are defined as a distinctive group in the Bacteria. However, members of the two taxa that comprise this group, the green sulfur bacteria...... (Chlorobi) and the filamentous anoxygenic phototrophic bacteria ("Chloroflexales"), are otherwise quite different, both physiologically and phylogenetically. This review summarizes how genome sequence information facilitated studies of the biosynthesis and function of the photosynthetic apparatus...... a and carotenoid biosynthesis enzymes, gene cluster analysis in Cfx. aurantiacus, and gene inactivation studies in Chl. tepidum. Based on these results, BChl a and BChl c biosynthesis is similar in the two organisms, whereas carotenoid biosynthesis differs significantly. In agreement with its facultative anaerobic...

  7. Calculation of the radiative properties of photosynthetic microorganisms

    International Nuclear Information System (INIS)

    Dauchet, Jérémi; Blanco, Stéphane; Cornet, Jean-François; Fournier, Richard

    2015-01-01

    A generic methodological chain for the predictive calculation of the light-scattering and absorption properties of photosynthetic microorganisms within the visible spectrum is presented here. This methodology has been developed in order to provide the radiative properties needed for the analysis of radiative transfer within photobioreactor processes, with a view to enable their optimization for large-scale sustainable production of chemicals for energy and chemistry. It gathers an electromagnetic model of light-particle interaction along with detailed and validated protocols for the determination of input parameters: morphological and structural characteristics of the studied microorganisms as well as their photosynthetic-pigment content. The microorganisms are described as homogeneous equivalent-particles whose shape and size distribution is characterized by image analysis. The imaginary part of their refractive index is obtained thanks to a new and quite extended database of the in vivo absorption spectra of photosynthetic pigments (that is made available to the reader). The real part of the refractive index is then calculated by using the singly subtractive Kramers–Krönig approximation, for which the anchor point is determined with the Bruggeman mixing rule, based on the volume fraction of the microorganism internal-structures and their refractive indices (extracted from a database). Afterwards, the radiative properties are estimated using the Schiff approximation for spheroidal or cylindrical particles, as a first step toward the description of the complexity and diversity of the shapes encountered within the microbial world. Finally, these predictive results are confronted to experimental normal-hemispherical transmittance spectra for validation. This entire procedure is implemented for Rhodospirillum rubrum, Arthrospira platensis and Chlamydomonas reinhardtii, each representative of the main three kinds of photosynthetic microorganisms, i.e. respectively

  8. Calculation of the radiative properties of photosynthetic microorganisms

    Science.gov (United States)

    Dauchet, Jérémi; Blanco, Stéphane; Cornet, Jean-François; Fournier, Richard

    2015-08-01

    A generic methodological chain for the predictive calculation of the light-scattering and absorption properties of photosynthetic microorganisms within the visible spectrum is presented here. This methodology has been developed in order to provide the radiative properties needed for the analysis of radiative transfer within photobioreactor processes, with a view to enable their optimization for large-scale sustainable production of chemicals for energy and chemistry. It gathers an electromagnetic model of light-particle interaction along with detailed and validated protocols for the determination of input parameters: morphological and structural characteristics of the studied microorganisms as well as their photosynthetic-pigment content. The microorganisms are described as homogeneous equivalent-particles whose shape and size distribution is characterized by image analysis. The imaginary part of their refractive index is obtained thanks to a new and quite extended database of the in vivo absorption spectra of photosynthetic pigments (that is made available to the reader). The real part of the refractive index is then calculated by using the singly subtractive Kramers-Krönig approximation, for which the anchor point is determined with the Bruggeman mixing rule, based on the volume fraction of the microorganism internal-structures and their refractive indices (extracted from a database). Afterwards, the radiative properties are estimated using the Schiff approximation for spheroidal or cylindrical particles, as a first step toward the description of the complexity and diversity of the shapes encountered within the microbial world. Finally, these predictive results are confronted to experimental normal-hemispherical transmittance spectra for validation. This entire procedure is implemented for Rhodospirillum rubrum, Arthrospira platensis and Chlamydomonas reinhardtii, each representative of the main three kinds of photosynthetic microorganisms, i.e. respectively

  9. Drivers of Global Vegetation Biomass Trends between 1988 and 2008

    KAUST Repository

    McCabe, Matthew

    2013-12-01

    Vegetation optical depth (VOD) is an indicator of the vegetation water content of both woody and leaf components in terrestrial biomass as derived from passive microwave observations. VOD is distinctly different from products derived from optical remote sensing: it is less prone to saturation in dense canopy; is sensitive to both photosynthetic and non-photosynthetic biomass; is less affected by atmospheric conditions; and is of coarser spatial resolution. Here, VOD retrievals from a series of sensors are blended to produce a time series from 1988 through to 2008, and a global analysis is undertaken to quantify and attribute global VOD trends over the same period. We conduct Mann-Kendall linear trend tests on annual average VOD to identify regions of significant change. Patterns for these regions were evaluated against independent datasets to diagnose the underlying cause of the observed trends. Results indicate that: (1) over grassland and shrubland, VOD patterns correspond strongly to temporal precipitation patterns; (2) over croplands, annual average VOD shows a general increase that corresponds to reported crop yield patterns and can be attributed to a combination of precipitation patterns and agricultural improvement; (3) over humid tropical forest, the spatial pattern of VOD decline agrees well with deforestation patterns identified in previous studies; and (4) over boreal forests, regional VOD declines can be attributed to a combination of fires and logging. We conclude that VOD can be used to estimate and interpret global changes in total above ground vegetation biomass. We expect that this new observationally based remote sensing data source will be of considerable interest to hydrological, agricultural, climate change and carbon cycle studies, and provide new insights into these and related process investigations.

  10. Drivers of Global Vegetation Biomass Trends between 1988 and 2008

    KAUST Repository

    McCabe, Matthew; Liu, Yi; Evans, Jason; De Jeu, Richard; van Dijk, Albert

    2013-01-01

    Vegetation optical depth (VOD) is an indicator of the vegetation water content of both woody and leaf components in terrestrial biomass as derived from passive microwave observations. VOD is distinctly different from products derived from optical remote sensing: it is less prone to saturation in dense canopy; is sensitive to both photosynthetic and non-photosynthetic biomass; is less affected by atmospheric conditions; and is of coarser spatial resolution. Here, VOD retrievals from a series of sensors are blended to produce a time series from 1988 through to 2008, and a global analysis is undertaken to quantify and attribute global VOD trends over the same period. We conduct Mann-Kendall linear trend tests on annual average VOD to identify regions of significant change. Patterns for these regions were evaluated against independent datasets to diagnose the underlying cause of the observed trends. Results indicate that: (1) over grassland and shrubland, VOD patterns correspond strongly to temporal precipitation patterns; (2) over croplands, annual average VOD shows a general increase that corresponds to reported crop yield patterns and can be attributed to a combination of precipitation patterns and agricultural improvement; (3) over humid tropical forest, the spatial pattern of VOD decline agrees well with deforestation patterns identified in previous studies; and (4) over boreal forests, regional VOD declines can be attributed to a combination of fires and logging. We conclude that VOD can be used to estimate and interpret global changes in total above ground vegetation biomass. We expect that this new observationally based remote sensing data source will be of considerable interest to hydrological, agricultural, climate change and carbon cycle studies, and provide new insights into these and related process investigations.

  11. Ameliorative effect of salicylic acid and theophylline on photosynthetic pigment content in gamma irradiated french bean varieties, using "6"0Co as a source

    International Nuclear Information System (INIS)

    Shukla, Pradeep K.; Vishwakarma, Kapil Kumar; Shukla, Saumya; Sharma, Richa; Ramteke, P.W.; Misra, Pragati

    2017-01-01

    Irradiation of seeds may cause genetic variability that enable plant breeders to select new genotypes with improved qualitative and quantitative characteristics. An experiment was conducted to study the protective role of salicylic acid and theophylline on photosynthetic pigments of gamma exposed french bean. Seeds of four French bean were treated by different doses of gamma radiation using "6"0Co as source. The results showed that the application of salicylic acid and theophylline significantly increased chlorophyll a content, chlorophyll b content, total chlorophyll content and carotenoid content. Salicylic acid was more effective than theophylline in overcoming the radiation effects and therefore, showed more protection to the photosynthetic pigments. (author)

  12. How well do growing season dynamics of photosynthetic capacity correlate with leaf biochemistry and climate fluctuations?

    Science.gov (United States)

    Way, Danielle A; Stinziano, Joseph R; Berghoff, Henry; Oren, Ram

    2017-07-01

    Accurate values of photosynthetic capacity are needed in Earth System Models to predict gross primary productivity. Seasonal changes in photosynthetic capacity in these models are primarily driven by temperature, but recent work has suggested that photoperiod may be a better predictor of seasonal photosynthetic capacity. Using field-grown kudzu (Pueraria lobata (Willd.) Ohwi), a nitrogen-fixing vine species, we took weekly measurements of photosynthetic capacity, leaf nitrogen, and pigment and photosynthetic protein concentrations and correlated these with temperature, irradiance and photoperiod over the growing season. Photosynthetic capacity was more strongly correlated with photoperiod than with temperature or daily irradiance, while the growing season pattern in photosynthetic capacity was uncoupled from changes in leaf nitrogen, chlorophyll and Rubisco. Daily estimates of the maximum carboxylation rate of Rubisco (Vcmax) based on either photoperiod or temperature were correlated in a non-linear manner, but Vcmax estimates from both approaches that also accounted for diurnal temperature fluctuations were similar, indicating that differences between these models depend on the relevant time step. We advocate for considering photoperiod, and not just temperature, when estimating photosynthetic capacity across the year, particularly as climate change alters temperatures but not photoperiod. We also caution that the use of leaf biochemical traits as proxies for estimating photosynthetic capacity may be unreliable when the underlying relationships between proxy leaf traits and photosynthetic capacity are established outside of a seasonal framework. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  13. Comparison of Six DNA Extraction Procedures and the Application of Plastid DNA Enrichment Methods in Selected Non-photosynthetic Plants

    Directory of Open Access Journals (Sweden)

    Shin-Yi Shyu

    2013-12-01

    Full Text Available Genomic DNA was isolated using three DNA extraction commercial kits and three CTAB-based methods for two non-photosynthetic plants, Balanophora japonica and Mitrastemon kanehirai. The quality of the isolated DNA was evaluated and subjected to following restriction enzyme digestions. All six procedures yielded DNA of sufficient quality for PCR, and the method described by Barnwell et al. (1998 performed well in isolating DNA from both species for restriction enzyme digestion. In addition, we succeeded to enrich plastid DNA content by using the methods depending on a high salt buffer to deplete nuclear material. The ‘high salt’ methods based on protocol presented by Milligan (1989 were able to increase plastid DNA effectively and significantly reduce nuclear DNA from M. kanehirai. The plastid DNA enrichment protocols are inexpensive and not time-consuming, and may be applicable to other non-photosynthetic plants.

  14. Photosynthetic and Ultrastructure Parameters of Maize Plants are Affected During the Phyto-Rhizoremediation Process of Degraded Metal Working Fluids.

    Science.gov (United States)

    Grijalbo, Lucía; Gutierrez Mañero, Francisco Javier; Fernandez-Pascual, Mercedes; Lucas, Jose Antonio

    2015-01-01

    A phyto-rhizoremediation system using corn and esparto fiber as rooting support to remediate degraded metal working fluids (dMWFs) has been developed in the present study. In order to improve the process, plants were inoculated at the root level with bacteria either individually, and with a consortium of strains. All strains used were able to grow with MWFs. The results show that this system significantly lowers the Chemical Oxygen Demand below legal limits within 5 days. However, results were only improved with the bacterial consortium. Despite the effectiveness of the phyto-rhizoremediation process, plants are damaged at the photosynthetic level according to the photosynthetic parameters measured, as well as at the ultrastructure of the vascular cylinder and the Bundle Sheath Cells. Interestingly, the bacterial inoculation protects against this damage. Therefore, it seems that that the inoculation with bacteria can protect the plants against these harmful effects.

  15. Impact of Aerosols on Shortwave and Photosynthetically Active Radiation Balance over Sub-tropical Region in South Asia: Observational and Modeling Approach

    Science.gov (United States)

    Subba, T.; Pathak, B.

    2016-12-01

    The North-East Indian Region (NER) (22-30ºN, 89-98ºE) in south Asia sandwiched between two global biodiversity hotspots namely, Himalaya and Indo-Burma, assumes significance owing to its unique topography with mountains in the north, east and south and densely populated Indo Gangetic plains (IGP) towards the west resulting in complex aerosol system. Multi-year (2010-2014) concurrent measurements of aerosol properties and the shortwave radiation budget are examined over four geographically distinct stations of NER operational under Indian Space Research organization's ARFINET (Aerosol Radiative Forcing over India NETwork). An attempt has been made to lessen the ambiguity of forcing estimation by validating the radiative transfer modelled ARF with the CNR4 net radiometer measured values (r2 0.98). The Normalized Difference Vegetation Index and its dependence on the extinction of the photosynthetically active radiation (PAR) due to aerosol are assessed. The spring time enhancement of aerosols in the column has shown significant surface cooling (ARF = -48 ± 5 Wm-2) over the region, while the very high Black Carbon (BC) mass concentrations near the surface (SSA > 0.8) leads to significant atmospheric warming (ARF = +41 ± 7 Wm-2) in the shortwave range. Radiative forcing estimates reveal that the atmospheric forcing by BC could be as high as +30Wm-2 over the western part, which are significantly higher than the eastern part with a consequent heating rate of 1.5 K day-1 revealing an east-west asymmetry over NER. The impact of BC aerosols on the photosynthetic rate varies among different locations ranging from -5±2 Wm-2 to -25±3 Wm-2. Almost 70% of the total atmospheric shortwave radiative absorption is attributed to just 10% contribution of Black Carbon (BC) to total mass concentration and causes a reduction of more than 30% of PAR reaching the surface over Brahmaputra valley due to direct radiative effect. Comparison of previous and the present study shows highest

  16. [Hydraulic limitation on photosynthetic rate of old Populus simonii trees in sandy soil of north Shaanxi Province].

    Science.gov (United States)

    Zuo, Li-Xiang; Li, Yang-Yang; Chen, Jia-Cun

    2014-06-01

    'Old and dwarf trees' on the loess plateau region mainly occurred among mature trees rather than among small trees. To elucidate the mechanism of tree age on 'old and dwarf trees' formation, taking Populus simonii, a tree species that accounted for the largest portion of 'old and dwarf trees' on the loess plateau, as an example, the growth, photosynthesis and hydraulic traits of P. simonii trees with different ages (young: 13-15 years, mid-aged: 31-34 years, and old: 49-54 years) were measured. The results showed that the dieback length increased, and net photosynthetic rate, stomatal conductance, transpiration rate, and whole plant hydraulic conductance decreased significantly with the increasing tree age. Both net photosynthetic rate and stomatal conductance measured at different dates were significantly and positively related to the whole plant hydraulic conductance, suggesting that the decreasing photosynthetic rate of old trees was possibly caused by the declined hydraulic conductance. Although the resistance to cavitation in stems and leaves was stronger in old trees than in young and mid-aged trees, there were no differences in midday native stem embolization degree and leaf hydraulic conductance based on the vulnerability curve estimation, suggesting that the increased hydraulic resistance of the soil-root system is probably the most important reason for decreasing the whole plant hydraulic conductance of old trees.

  17. The Influence of Different Interstock Lengths of Minneola Tanjelo on Photosynthetic Parameters and Fruit Yield of Star Ruby Grapefruit

    Directory of Open Access Journals (Sweden)

    Bilge Yılmaz

    2014-05-01

    Full Text Available In this study, Minneola Tangelo hybrid, a cross of grapefruit and mandarin (Duncan grapefruit x Dancy mandarin, used as interstock to Star Ruby grapefruit with different lengths. Effects of different interstock lengths on fruit yield and quality, plant development and photosynthetic parameters were investigated. According to the results, different interstock lengths significantly affected fruit yield and size. The highest fruit yield was determined in T-M20-S whereas the lowest was on T-M5-S. The highest fruit size were determined in Star Ruby fruits on T-M5-S and T-M40-S whereas the lowest on T-M20-S and T-S (control. T-M40-S and T-M20-S treatments markedly reduced stem diameter and tree canopy in comparison to other treatments and control. Usage of different interstock lengths did not significantly affected some of fruit quality traits, net photosynthetic rate, stomatal conductance, leaf transpiration rate, leaf water usage efficiency and leaf chlorophyll concentration. In regards to seasonal changes, net photosynthetic rate were higher in spring and summer seasons then winter and fall seasons.

  18. [Photosynthetic characteristics of Cuscuta japonica and its hosts during parasitization and after detachment].

    Science.gov (United States)

    Wang, Dong; Hu, Fei; Chen, Yu-Fen; Yang, Jun; Kong, Chui-Hua

    2007-08-01

    The study on the photosynthetic characteristics of Cuscuta japonica and its hosts showed that there was a negative correlation between the photosynthetic pigment content (PPC) of C. japonica and its hosts. The PPC increased in the C. japonica-preferred hosts' parasitized and neighboring leaves, but decreased in its less preferred hosts' parasitized and neighboring leaves. The leaves parasitized by C. japonica and their neighboring far from the parasitized ones had a lowered net photosynthesis rate P(n), and the decreasing order accorded with that of parasitization. The decrease of P(n) for C. japonica-less preferred hosts was mainly due to the stomatal factors, but that for the preferred hosts was regulated by multi-factors. Under light, the PPC of C. japonica detached from preferred hosts increased faster than that of C. japonica detached from less preferred hosts, but the dry matter decrease was in adverse. In dark, however, the changes in PPC and dry matter content of C. japonica were not significant, whatever hosts it was detached from.

  19. In vivo measurements of the seasonal photosynthetic fluorescence of the Mediterranean coral Cladocora caespitosa (L.

    Directory of Open Access Journals (Sweden)

    Andrea Peirano

    2007-12-01

    Full Text Available In situ photosynthetic fluorescence of the zooxanthellate Mediterranean coral Cladocora caespitosa (L. was measured seasonally on colonies from 5 to 27 m depth using an INF-300 Integrating Natural Fluorometer (Biospherical Instrument Inc.. This oceanographic instrument, used to measure the in vivo phytoplankton chlorophyll a (Chl a fluorescence, was adapted to record the natural fluorescence of C. caespitosa by SCUBA divers. The resulting curves of natural fluorescence of Chl a vs photosynthetically active radiation (PAR 400-700 nm showed that: (1 natural fluorescence was limited by light availability in both deep and shallow colonies in all seasons; (2 photosynthesis occurred in C. caespitosa also in winter, when temperature is low and seawater turbidity contributes significantly to PAR attenuation; and (3 the efficiency of the Chl a fluorescence increased from summer to winter. This last finding outlines the winter coupling between zooxanthellae activity and calcification processes and is consistent with the formation of the high density band in the coral skeleton.

  20. Elevated CO2 causes changes in the photosynthetic apparatus of a toxic cyanobacterium, Cylindrospermopsis raciborskii.

    Science.gov (United States)

    Pierangelini, Mattia; Stojkovic, Slobodanka; Orr, Philip T; Beardall, John

    2014-07-15

    We studied the physiological acclimation of growth, photosynthesis and CO2-concentrating mechanism (CCM) in Cylindrospermopsis raciborskii exposed to low (present day; L-CO2) and high (1300ppm; H-CO2) pCO2. Results showed that under H-CO2 the cell specific division rate (μc) was higher and the CO2- and light-saturated photosynthetic rates (Vmax and Pmax) doubled. The cells' photosynthetic affinity for CO2 (K0.5CO2) was halved compared to L-CO2 cultures. However, no significant differences were found in dark respiration rates (Rd), pigment composition and light harvesting efficiency (α). In H-CO2 cells, non-photochemical quenching (NPQ), associated with state transitions of the electron transport chain (ETC), was negligible. Simultaneously, a reorganisation of PSII features including antenna connectivity (JconPSIIα), heterogeneity (PSIIα/β) and effective absorption cross sectional area (σPSIIα/β) was observed. In relation to different activities of the CCM, our findings suggest that for cells grown under H-CO2: (1) there is down-regulation of CCM activity; (2) the ability of cells to use the harvested light energy is altered; (3) the occurrence of state transitions is likely to be associated with changes of electron flow (cyclic vs linear) through the ETC; (4) changes in PSII characteristics are important in regulating state transitions. Copyright © 2014 Elsevier GmbH. All rights reserved.

  1. Photosynthetic and enzymatic metabolism of Schinus terebinthifolius Raddi seedlings under water deficit

    Directory of Open Access Journals (Sweden)

    Danieli Pieretti Nunes

    Full Text Available ABSTRACT Schinus terebinthifolius Raddi is a tree species that can be used in the recovery of degraded areas, as it exhibits rapid growth and has a very expansive root system, facilitating water uptake from the deeper layers of the soil. The objective of this study was to evaluate photosynthesis and enzymatic activity in S. terebinthifolius seedlings under conditions of water deficit and their potential to recover following re-irrigation. The experiment was conducted in a greenhouse under a plastic covering where plants were distributed into two groups: Group 1 - control plants, where irrigation was maintained at 70% of the water retention capacity, and Group 2 - stressed plants, where irrigation was suspended until the photosynthetic rate neared zero, followed by rehydration for 12 days, then a further suspension of irrigation. At the beginning of the experiment and during the suspension of irrigation and rehydration, plants were evaluated for gas and antioxidant enzyme exchanges. Hydric stress significantly reduced photosynthesis, stomatal transpiration conductance, carboxylation efficiency of Rubisco, and the chlorophyll content of the S. terebinthifolius plants. Following rehydration, plants recovered the carboxylation efficiency of Rubisco, but not the photosynthetic rate. Antioxidant enzyme activity increased in both the aerial part and the root in response to water deficit.

  2. Remote sensing of photosynthetic-light-use efficiency of a Siberian boreal forest

    International Nuclear Information System (INIS)

    Nichol, C.J.; Grace, J.; Shibistova, O.; Matsubara, S.

    2002-01-01

    The relationship between a physiological index called the photochemical reflectance index (PRI) and photosynthetic light-use-efficiency (LUE) of a Siberian boreal forest during the winter-spring transition, or green-up period, was investigated in 2000. During this time the photosynthetic apparatus was considered under stress as a result of extremes of temperature (from -20 to 35 deg C) coupled with a high radiation load. Reflectance measurements of four stands were made from a helicopter-mounted spectro radiometer and PRI was calculated from these data. Eddy covariance towers were operating at the four stands and offered a means to calculate LUE. A significant linear relationship was apparent between PRI, calculated from the helicopter spectral data, and LUE, calculated from the eddy covariance data, for the four sites sampled. Reflectance measurements were also made of a Scots pine stand from the eddy covariance tower. Needles were also sampled during the time of spectral data acquisition for xanthophyll pigment determination. Strong linear relationships were observed among PRI, the epoxidation state of the xanthophyll cycle (EPS) and LUE over the green-up period and the diurnal cycle at the canopy scale

  3. Alternative oxidase: a respiratory electron transport chain pathway essential for maintaining photosynthetic performance during drought stress.

    Science.gov (United States)

    Vanlerberghe, Greg C; Martyn, Greg D; Dahal, Keshav

    2016-07-01

    Photosynthesis and respiration are the hubs of energy metabolism in plants. Drought strongly perturbs photosynthesis as a result of both diffusive limitations resulting from stomatal closure, and in some cases biochemical limitations that are associated with a reduced abundance of key photosynthetic components. The effects of drought on respiration, particularly respiration in the light (RL ), are less understood. The plant mitochondrial electron transport chain includes a non-energy conserving terminal oxidase called alternative oxidase (AOX). Several studies have shown that drought increases AOX transcript, protein and maximum capacity. Here we review recent studies comparing wild-type (WT) tobacco to transgenic lines with altered AOX protein amount. Specifically during drought, RL was compromised in AOX knockdown plants and enhanced in AOX overexpression plants, compared with WT. Significantly, these differences in RL were accompanied by dramatic differences in photosynthetic performance. Knockdown of AOX increased the susceptibility of photosynthesis to drought-induced biochemical limitations, while overexpression of AOX delayed the development of such biochemical limitations, compared with WT. Overall, the results indicate that AOX is essential to maintaining RL during drought, and that this non-energy conserving respiration maintains photosynthesis during drought by promoting energy balance in the chloroplast. This review also outlines several areas for future research, including the possibility that enhancement of non-energy conserving respiratory electron sinks may be a useful biotechnological approach to increase plant performance during stress. © 2016 Scandinavian Plant Physiology Society.

  4. Melatonin immunoreactivity in the photosynthetic prokaryote Rhodospirillum rubrum: implications for an ancient antioxidant system.

    Science.gov (United States)

    Manchester, L C; Poeggeler, B; Alvares, F L; Ogden, G B; Reiter, R J

    1995-01-01

    Rhodospirillum rubrum is a spiral anoxygenic photosynthetic bacterium that can exist under either aerobic or anaerobic conditions. The organism thrives in the presence of light or complete darkness and represents one of the oldest species of living organisms, possibly 2-3.5 billion years old. The success of this prokaryotic species may be attributed to the evolution of certain indole compounds that offer protection against life-threatening oxygen radicals produced by an evolutionary harsh environment. Melatonin, N-acetyl-5-methoxytryptamine, is an indolic highly conserved molecule that exists in protists, plants, and animals. This study was undertaken to determine the presence of an immunoreactive melatonin in the kingdom Monera and particularly in the photosynthetic bacterium, R. rubrum, under conditions of prolonged darkness or prolonged light. Immunoreactive melatonin was measured during both the extended day and extended night. Significantly more melatonin was observed during the scotophase than the photophase. This study marks the first demonstration of melatonin in a bacterium. The high level of melatonin observed in bacteria may provide on-site protection of bacterial DNA against free radical attack.

  5. Photosynthetic and Heterotrophic Ferredoxin Isoproteins Are Colocalized in Fruit Plastids of Tomato1

    Science.gov (United States)

    Aoki, Koh; Yamamoto, Miyuki; Wada, Keishiro

    1998-01-01

    Fruit tissues of tomato (Lycopersicon esculentum Mill.) contain both photosynthetic and heterotrophic ferredoxin (FdA and FdE, respectively) isoproteins, irrespective of their photosynthetic competence, but we did not previously determine whether these proteins were colocalized in the same plastids. In isolated fruit chloroplasts and chromoplasts, both FdA and FdE were detected by immunoblotting. Colocalization of FdA and FdE in the same plastids was demonstrated using double-staining immunofluorescence microscopy. We also found that FdA and FdE were colocalized in fruit chloroplasts and chloroamyloplasts irrespective of sink status of the plastid. Immunoelectron microscopy demonstrated that FdA and FdE were randomly distributed within the plastid stroma. To investigate the significance of the heterotrophic Fd in fruit plastids, Glucose 6-phosphate dehydrogenase (G6PDH) activity was measured in isolated fruit and leaf plastids. Fruit chloroplasts and chromoplasts showed much higher G6PDH activity than did leaf chloroplasts, suggesting that high G6PDH activity is linked with FdE to maintain nonphotosynthetic production of reducing power. This result suggested that, despite their morphological resemblance, fruit chloroplasts are functionally different from their leaf counterparts. PMID:9765529

  6. Salinity-induced modulation of plant growth and photosynthetic parameters in faba bean (vicia faba) cultivars

    International Nuclear Information System (INIS)

    Hussein, M.; Embiale, A.; Husen, A.; Eref, I.E.

    2017-01-01

    Salinity is one of the most severe environmental factors limiting the productivity of agricultural crops. The present study assesses salt-tolerant cultivars of Vicia faba L.on the basis of their growth, biomass and foliar characteristics. Four levels of salt stress (0, 50, 100 and 150mM) were applied to three selected cultivars, viz. Degaga, Dosha and Hachalu. Results revealed significant differences among the cultivars, salt-stress treatments, and their interaction, indicating the cultivars' variability and differential response to salt stress. Salinity stress adversely affected plant growth, plant water status and biomass production. Salt treatments decreased the chlorophyll a and chlorophyll b contents, but cultivar Dosha, which was ahead of others in height, leaf number, relative water content, total biomass and leaf-dry-mass ratio, was least affected. Functional leaf characters, such as photochemical efficiency of PSII (maximum quantum yield = Fv/Fm), stomatal conductance (gs), net photosynthetic rate (Pn) and transpiration rate (E) were also reduced under salt-stress, and againDosha cultivar did better than others except in gs. The relatively less decline in growth, water status, biomass, photosynthetic pigments and functional leaf characters of Dosha exhibits a reasonable tolerance ability of this cultivar, while the other two varieties viz., Degaga and Hachalu proved to be sensitive to salt stress. (author)

  7. The effects of coal dust on photosynthetic performance of the mangrove, Avicennia marina in Richards Bay, South Africa

    International Nuclear Information System (INIS)

    Naidoo, G.; Chirkoot, D.

    2004-01-01

    Richards Bay, on the northern KwaZulu-Natal coast, is the largest coal exporting port in South Africa. The coal is stored at the Richards Bay Coal Terminal (RBCT) prior to export. Dust from coal operations is a major problem in the Richards Bay area. In this study, we tested the hypothesis that coal dust adversely affects photosynthetic performance of Avicennia marina (Forssk.) Vierh., the dominant mangrove species in the harbour. Photosynthetic performance was determined on 10 trees by measuring carbon dioxide uptake and chlorophyll fluorescence parameters at two elevation sites and on upper and lower leaf surfaces that were covered or uncovered with coal dust. Measurements were made on five clear, sunny days at saturating light (>1000 μmol m -2 s -1 ) and high temperature (28-30 deg. C). Coal dust significantly reduced carbon dioxide exchange of upper and lower leaf surfaces by 17-39%, the reduction being generally greater on the lower leaf surface that is covered by a dense mat of trichomes and salt glands. The reduction in carbon dioxide exchange by coal dust was higher at the high elevation site that supported isolated dwarfed trees. The chlorophyll fluorescence data indicated that leaves coated with dust exhibited significantly lower photosystem II (PS II) quantum yield, lower electron transport rate (ETR) through PSII and reduced quantum efficiency of PSII (F v F m ). The chlorophyll fluorescence data supported the gas exchange measurements and are consistent with reduced photosynthetic performance of leaves coated with coal dust. - Coal dust reduced photosynthetic performance of the mangrove, Avicennia marina

  8. Short-term light and leaf photosynthetic dynamics affect estimates of daily understory photosynthesis in four tree species.

    Science.gov (United States)

    Naumburg, Elke; Ellsworth, David S

    2002-04-01

    Instantaneous measurements of photosynthesis are often implicitly or explicitly scaled to longer time frames to provide an understanding of plant performance in a given environment. For plants growing in a forest understory, results from photosynthetic light response curves in conjunction with diurnal light data are frequently extrapolated to daily photosynthesis (A(day)), ignoring dynamic photosynthetic responses to light. In this study, we evaluated the importance of two factors on A(day) estimates: dynamic physiological responses to photosynthetic photon flux density (PPFD); and time-resolution of the PPFD data used for modeling. We used a dynamic photosynthesis model to investigate how these factors interact with species-specific photosynthetic traits, forest type, and sky conditions to affect the accuracy of A(day) predictions. Increasing time-averaging of PPFD significantly increased the relative overestimation of A(day) similarly for all study species because of the nonlinear response of photosynthesis to PPFD (15% with 5-min PPFD means). Depending on the light environment characteristics and species-specific dynamic responses to PPFD, understory tree A(day) can be overestimated by 6-42% for the study species by ignoring these dynamics. Although these overestimates decrease under cloudy conditions where direct sunlight and consequently understory sunfleck radiation is reduced, they are still significant. Within a species, overestimation of A(day) as a result of ignoring dynamic responses was highly dependent on daily sunfleck PPFD and the frequency and irradiance of sunflecks. Overall, large overestimates of A(day) in understory trees may cause misleading inferences concerning species growth and competition in forest understories with sunlight. We conclude that comparisons of A(day) among co-occurring understory species in deep shade will be enhanced by consideration of sunflecks by using high-resolution PPFD data and understanding the physiological

  9. Ozone Effects on Fruit Productivity and Photosynthetic Response of Two Tomato Cultivars in Relation to Stomatal Fluxes

    Directory of Open Access Journals (Sweden)

    Giacomo Gerosa

    Full Text Available An Open-Top Chamber experiment on two tomato cultivars (cv. Oxheart and cv. San Marzano was carried out in Curno (Northern Italy between June and September 2007. Two ozone treatments were applied for a 3.5 months period: Non-Filtered OTC (NF-OTC, 95% of ambient ozone and Charcoal-Filtered OTC (CF-OTC, 50% of ambient ozone. Diurnal cycles of porometry measurements were performed during the season and allowed to draw a stomatal conductance model for each cultivar in order to calculate the ozone stomatal fluxes taken up by plants. Assessments on fruits yield were performed during the season, taking into account the number of fruits, their fresh weight and their marketability. In addition, measurements on the chlorophyll fluorescence of photosystems were carried out to assess possible negative effects on photosynthetic efficiency. Despite the two cultivars absorbed a similar ozone stomatal dose during the season (with an 8% difference, their responses to ozone treatments were totally divergent in relation to both fruits yield and photosynthetic efficiency. Plants of cv. Oxheart grown in NF-OTCs showed significant yield loss in the total weight of fruits (-35.9% which is exclusively related to a decrease in the number of fruits produced (-35.7% of total fruits; -30.6% of marketable fruits, since mean fresh weight of fruits remained unaffected. Moreover the same plants displayed low values (in comparison to CF-OTCs plants of the photosynthetic efficiency index (PIabs during the most intense period of ozone stress (July occurred in the flowering stage of plants and at the beginning of fructification. Plants of the cv. San Marzano had an opposite response behaviour with an increase of the mean fresh weight of fruits in plants grown in NF-OTC (even if not statistically significant and no difference in the number of fruits produced and in the values of photosynthetic efficiency.

  10. Morphological Characterization of Photosynthetic Microbial Granule from Palm Oil Mill Effluent (POME)

    International Nuclear Information System (INIS)

    Najib, M.Z.M.

    2013-01-01

    Presently, global warming is the most highlighted subjects in the environmental issues which relates closely to greenhouse gases (GHG) emissions. In 2007, the Intergovernmental Panel on Climate Change (IPCC) assigns only methane (CH 4 ) emissions to wastewater treatment rather than GHG emissions specifically carbon dioxide (CO 2 ) gas from the aerobic treatment processes. Focusing on the palm oil industry in Malaysia, the most commonly used treatment of palm oil mill effluent (POME) which is the conventional pounding system, has caused excessive generation of GHG such as CH 4 and CO 2 gases. To develop a novel, innovative and environmental-friendly mitigation method, this study explores into the possibility of growing the photosynthetic bacteria in the form of granules via the aerobic granulation process with potential applications in reducing CO 2 gases. The cultivation of photosynthetic microbial granules was investigated using POME as the substrate in a sequencing batch reactor (SBR) system via the sequencing cycle of feeding, reacting, settling and decanting. Evidence of the formation of granule was based on microscopic examination of the morphological changes during the development of the granule in the SBR system over a period of 90 days. It shows changes from dispersed loose structure of the sludge merging into small flocs of irregular shapes and finally into dense and compact granular form. The granule was formed by applying an organic loading rate (OLR) at 2.75 kg COD/ m 3 .day, hydraulic retention time (HRT) at 4 h and superficial air velocity of 2.07 cm/ s. The biomass concentration began to decreased first (initial sludge biomass = 16750 mg/ L) and then increased steadily to a constant value of 32000 mg/ L after 90 days. Besides, the results also demonstrated a good accumulation of biomass as the settleability between raw sludge and granule increased from 0.03 cm/ s to 0.94 cm/ s. The maximum settling velocity obtained in the reactor was approximately 2

  11. Robustness, efficiency, and optimality in the Fenna-Matthews-Olson photosynthetic pigment-protein complex

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Lewis A.; Habershon, Scott, E-mail: S.Habershon@warwick.ac.uk [Department of Chemistry and Centre for Scientific Computing, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2015-09-14

    Pigment-protein complexes (PPCs) play a central role in facilitating excitation energy transfer (EET) from light-harvesting antenna complexes to reaction centres in photosynthetic systems; understanding molecular organisation in these biological networks is key to developing better artificial light-harvesting systems. In this article, we combine quantum-mechanical simulations and a network-based picture of transport to investigate how chromophore organization and protein environment in PPCs impacts on EET efficiency and robustness. In a prototypical PPC model, the Fenna-Matthews-Olson (FMO) complex, we consider the impact on EET efficiency of both disrupting the chromophore network and changing the influence of (local and global) environmental dephasing. Surprisingly, we find a large degree of resilience to changes in both chromophore network and protein environmental dephasing, the extent of which is greater than previously observed; for example, FMO maintains EET when 50% of the constituent chromophores are removed, or when environmental dephasing fluctuations vary over two orders-of-magnitude relative to the in vivo system. We also highlight the fact that the influence of local dephasing can be strongly dependent on the characteristics of the EET network and the initial excitation; for example, initial excitations resulting in rapid coherent decay are generally insensitive to the environment, whereas the incoherent population decay observed following excitation at weakly coupled chromophores demonstrates a more pronounced dependence on dephasing rate as a result of the greater possibility of local exciton trapping. Finally, we show that the FMO electronic Hamiltonian is not particularly optimised for EET; instead, it is just one of many possible chromophore organisations which demonstrate a good level of EET transport efficiency following excitation at different chromophores. Overall, these robustness and efficiency characteristics are attributed to the highly

  12. Robustness, efficiency, and optimality in the Fenna-Matthews-Olson photosynthetic pigment-protein complex

    International Nuclear Information System (INIS)

    Baker, Lewis A.; Habershon, Scott

    2015-01-01

    Pigment-protein complexes (PPCs) play a central role in facilitating excitation energy transfer (EET) from light-harvesting antenna complexes to reaction centres in photosynthetic systems; understanding molecular organisation in these biological networks is key to developing better artificial light-harvesting systems. In this article, we combine quantum-mechanical simulations and a network-based picture of transport to investigate how chromophore organization and protein environment in PPCs impacts on EET efficiency and robustness. In a prototypical PPC model, the Fenna-Matthews-Olson (FMO) complex, we consider the impact on EET efficiency of both disrupting the chromophore network and changing the influence of (local and global) environmental dephasing. Surprisingly, we find a large degree of resilience to changes in both chromophore network and protein environmental dephasing, the extent of which is greater than previously observed; for example, FMO maintains EET when 50% of the constituent chromophores are removed, or when environmental dephasing fluctuations vary over two orders-of-magnitude relative to the in vivo system. We also highlight the fact that the influence of local dephasing can be strongly dependent on the characteristics of the EET network and the initial excitation; for example, initial excitations resulting in rapid coherent decay are generally insensitive to the environment, whereas the incoherent population decay observed following excitation at weakly coupled chromophores demonstrates a more pronounced dependence on dephasing rate as a result of the greater possibility of local exciton trapping. Finally, we show that the FMO electronic Hamiltonian is not particularly optimised for EET; instead, it is just one of many possible chromophore organisations which demonstrate a good level of EET transport efficiency following excitation at different chromophores. Overall, these robustness and efficiency characteristics are attributed to the highly

  13. Interactive effects of copper stress and arbuscular mycorrhizal fungi on photosynthetic characteristics and chlorphyl fluorescence parameters of elsholtzia splendens

    International Nuclear Information System (INIS)

    Li, Y.; Jin, Z.; Li, J.

    2017-01-01

    To determine interactive effects of added copper (Cu) and arbuscular mycorrhizal fungi (AMF) inoculation on the photosynthesis of Elsholtzia splendens, a greenhouse pot experiment was conducted. Four treatments were used, including -Cu-AMF (no Cu addition and no AMF inoculation), +Cu-AMF (Cu addition but no AMF inoculation), -Cu+AMF (no Cu addition and AMF inoculation), and +Cu+AMF (Cu addition and AMF inoculation). Cu addition did not change diurnal variation curves of the net photosynthetic rate(PN), the intercellular CO/sub 2/ concentration (Ci), the stomatal conductance (gs), or the transpiration rate (E); however, it significantly decreased the daily mean PN, gs, E, light-use efficiency (LUE), and carboxylation efficiency (CE). Furthermore, AMF inoculation significantly increased the daily mean PN, gs, LUE, and CE of E. splendens. In response to light, Cu addition significantly decreased the light-saturated net photosynthetic rate (PNmax), the light saturation point (LSP), the light compensation point (LCP), and the apparent quantum yield (AQY), while AMF inoculation significantly increased PNmax and AQY. In response to the CO/sub 2/ concentration, Cu addition significantly decreased PNmax and the CO/sub 2/ saturation point (CSP), while AMF inoculation significantly increased PNmax. Both Cu addition and AMF inoculation significantly decreased the relative chlorophyll content. Compared to the negative control treatment (-Cu-AMF), Cu addition significantly increased the minimal fluorescence, but significantly decreased maximal fluorescence, variable fluorescence,and maximum photochemical efficiency of PSII. These results suggest that AMF inoculations alleviate the inhibitory effect of copper stress on E. splendens plants by weakening its toxic effects on the photosynthetic apparatus and pigments. (author)

  14. The temporal and species dynamics of photosynthetic acclimation in flag leaves of rice (Oryza sativa) and wheat (Triticum aestivum) under elevated carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J.; Zeng, Q.; Xie, Z.; Tang, H.; Zhu, C. (Chinese Academy of Sciences. State Key Lab. of Soil and Sustainable Agriculture, Institute of Soil Science, Nanjing (China)); Hasegawa, T. (National Institute for Agro-Environmental Sciences. Agro-Meteorology Div., Tsukuba (Japan)); Ziska, L. (Crop Systems and Global Change Lab., Beltsville, MD (United States)); Jia, X. (Chinese Academic of Sciences/Nanjing Botanical Garden Memorial Sun Yat-Sen. Jiangsu Institute of Botany, Nanjing (China))

    2012-07-15

    In this study, we tested for the temporal occurrence of photosynthetic acclimation to elevated [CO{sub 2}] in the flag leaf of two important cereal crops, rice and wheat. In order to characterize the temporal onset of acclimation and the basis for any observed decline in photosynthetic rate, we characterized net photosynthesis, g{sub s}, g{sub m}, C{sub i}/C{sub a}, C{sub i}/C{sub c}, V{sub cmax}, J{sub max}, cell wall thickness, content of Rubisco, cytochrome (Cyt) f, N, chlorophyll and carbohydrate, mRNA expression for rbcL and petA, activity for Rubisco, sucrose phosphate synthase (SPS) and sucrose synthase (SS) at full flag expansion, mid-anthesis and the late grain-filling stage. No acclimation was observed for either crop at full flag leaf expansion. However, at the mid-anthesis stage, photosynthetic acclimation in rice was associated with RuBP carboxylation and regeneration limitations, while wheat only had the carboxylation limitation. By grain maturation, the decline of Rubisco content and activity had contributed to RuBP carboxylation limitation of photosynthesis in both crops at elevated [CO{sub 2}]; however, the sharp decrease of Rubisco enzyme activity played a more important role in wheat. Although an increase in non-structural carbohydrates did occur during these later stages, it was not consistently associated with changes in SPS and SS or photosynthetic acclimation. Rather, over time elevated [CO{sub 2}] appeared to enhance the rate of N degradation and senescence so that by late-grain fill, photosynthetic acclimation to elevated [CO{sub 2}] in the flag leaf of either species was complete. These data suggest that the basis for photosynthetic acclimation with elevated [CO{sub 2}] may be more closely associated with enhanced rates of senescence, and, as a consequence, may be temporally dynamic, with significant species variation. (Author)

  15. No prognostic significance of chronic infection with Chlamydia pneumoniae in acute coronary syndromes: insights from the Global Utilization of Strategies to Open Occluded Arteries IV Acute Coronary Syndromes trial

    DEFF Research Database (Denmark)

    Westerhout, Cynthia M; Gnarpe, Judy; Chang, Wei-Ching

    2007-01-01

    case-control substudy of the Global Utilization of Strategies to Open Occluded Arteries IV Acute Coronary Syndromes trial, 295 cases (30-day death/myocardial infarction [MI]) were matched by age, sex, baseline creatine kinase-myocardial kinase, and smoking status with 295 control subjects. To test...

  16. Simulation of the Unexpected Photosynthetic Seasonality in Amazonian Evergreen Forests by Using an Improved Diffuse Fraction-Based Light Use Efficiency Model

    Science.gov (United States)

    Yan, Hao; Wang, Shao-Qiang; da Rocha, Humberto R.; Rap, Alexandru; Bonal, Damien; Butt, Nathalie; Coupe, Natalia Restrepo; Shugart, Herman H.

    2017-11-01

    Understanding the mechanism of photosynthetic seasonality in Amazonian evergreen forests is critical for its formulation in global climate and carbon cycle models. However, the control of the unexpected photosynthetic seasonality is highly uncertain. Here we use eddy-covariance data across a network of Amazonian research sites and a novel evapotranspiration (E) and two-leaf-photosynthesis-coupled model to investigate links between photosynthetic seasonality and climate factors on monthly scales. It reproduces the GPP seasonality (R2 = 0.45-0.69) with a root-mean-square error (RMSE) of 0.67-1.25 g C m-2 d-1 and a Bias of -0.03-1.04 g C m-2 d-1 for four evergreen forest sites. We find that the proportion of diffuse and direct sunlight governs the photosynthetic seasonality via their interaction with sunlit and shaded leaves, supported by a proof that canopy light use efficiency (LUE) has a strong linear relationship with the fraction of diffuse sunlight for Amazonian evergreen forests. In the transition from dry season to rainy season, incident total radiation (Q) decreased while LUE and diffuse fraction increased, which produced the large seasonal increase ( 34%) in GPP of evergreen forests. We conclude that diffuse radiation is an important environmental driver of the photosynthetic seasonality in tropical Amazon forests yet depending on light utilization by sunlit and shaded leaves. Besides, the GPP model simulates the precipitation-dominated GPP seasonality (R2 = 0.40-0.69) at pasture and savanna sites. These findings present an improved physiological method to relate light components with GPP in tropical Amazon.

  17. Revealing Linear Aggregates of Light Harvesting Antenna Proteins in Photosynthetic Membranes

    OpenAIRE

    He, Yufan; Zeng, Xiaohua; Mukherjee, Saptarshi; Rajapaksha, Suneth; Kaplan, Samuel; Lu, H. Peter

    2010-01-01

    How light energy is harvested in a natural photosynthetic membrane through energy transfer is closely related to the stoichiometry and arrangement of light harvesting antenna proteins in the membrane. The specific photosynthetic architecture facilitates a rapid and efficient energy transfer among the light harvesting proteins (LH2 and LH1) and to the reaction center. Here we report the identification of linear aggregates of light harvesting proteins, LH2, in the photosynthetic membranes under...

  18. Photoelectrochemical cells based on photosynthetic systems: a review

    Directory of Open Access Journals (Sweden)

    Roman A. Voloshin

    2015-06-01

    Full Text Available Photosynthesis is a process which converts light energy into energy contained in the chemical bonds of organic compounds by photosynthetic pigments such as chlorophyll (Chl a, b, c, d, f or bacteriochlorophyll. It occurs in phototrophic organisms, which include higher plants and many types of photosynthetic bacteria, including cyanobacteria. In the case of the oxygenic photosynthesis, water is a donor of both electrons and protons, and solar radiation serves as inexhaustible source of energy. Efficiency of energy conversion in the primary processes of photosynthesis is close to 100%. Therefore, for many years photosynthesis has attracted the attention of researchers and designers looking for alternative energy systems as one of the most efficient and eco-friendly pathways of energy conversion. The latest advances in the design of optimal solar cells include the creation of converters based on thylakoid membranes, photosystems, and whole cells of cyanobacteria immobilized on nanostructured electrode (gold nanoparticles, carbon nanotubes, nanoparticles of ZnO and TiO2. The mode of solar energy conversion in photosynthesis has a great potential as a source of renewable energy while it is sustainable and environmentally safety as well. Application of pigments such as Chl f and Chl d (unlike Chl a and Chl b, by absorbing the far red and near infrared region of the spectrum (in the range 700-750 nm, will allow to increase the efficiency of such light transforming systems. This review article presents the last achievements in the field of energy photoconverters based on photosynthetic systems.

  19. Photosynthetically active radiation and comparison of methods for its estimation in equatorial Singapore

    Science.gov (United States)

    Tan, Puay Yok; Ismail, Mirza Rifqi Bin

    2016-02-01

    Photosynthetically active radiation (PAR) is an important input variable for urban climate, crop modelling and ecosystem services studies. Despite its importance, only a few empirical studies have been conducted on PAR, its relationship to global solar radiation and sky conditions and its estimation in the tropics. We report in this study, the characterisation of PAR in Singapore through direct measurements and development of models for its estimation using input variables of global solar radiation ( H), photometric radiation ( L), clearness index ( k t ) and sky view factor (SVF). Daily PAR showed a good correlation with daily H and had a comparatively small seasonal variation in PAR due to Singapore's equatorial position. The ratio of PAR to H ( PAR/ H) showed a slight depression in midyear from May to August, which correlated well with seasonal patterns in rainfall over the study period. Hourly PAR/ H increased throughout the day. Three empirical models developed in this study were able to predict daily PAR satisfactorily, with the most accurate model being one which included both H and k t as independent variables. A regression model for estimation of PAR under shaded conditions using SVF produced satisfactory estimation of daily PAR but was prone to high mean percentage error at low PAR levels.

  20. Canopy uptake of atmospheric N deposition at a conifer forest: part I -canopy N budget, photosynthetic efficiency and net ecosystem exchange

    International Nuclear Information System (INIS)

    Sievering, H.; Tomaszewski, T.; Torizzo, J.

    2007-01-01

    Global carbon cycle assessments of anthropogenic nitrogen (N) deposition influences on carbon sequestration often assume enhanced sequestration results. This assumption was evaluated at a Rocky Mountains spruce-fir forest. Forest canopy N uptake (CNU) of atmospheric N deposition was estimated by combining event wet and throughfall N fluxes with gradient measured HNO 3 and NH 3 as well as inferred (NO x and particulate N) dry fluxes. Approximately 80% of the growing-season 3 kg N/ha total deposition is retained in canopy foliage and branches. This CNU constitutes ∼1/3 of canopy growing season new N supply at this conifer forest site. Daytime net ecosystem exchange (NEE) significantly (P = 0.006) and negatively (CO 2 uptake) correlated with CNU. Multiple regression indicates ∼20% of daytime NEE may be attributed to CNU (P < 0.02); more than soil water content. A wet deposition N-amendment study (Tomaszewski and Sievering), at canopy spruce branches, increased their growing-season CNU by 40-50% above ambient. Fluorometry and gas exchange results show N-amended spruce branches had greater photosynthetic efficiency and higher carboxylation rates than control and untreated branches. N-amended branches had 25% less photoinhibition, with a 5-9% greater proportion of foliar-N-in-Rubisco. The combined results provide, partly, a mechanistic explanation for the NEE dependence on CNU

  1. Effect of chromone-substituted benzothiazolium halides on photosynthetic processes

    International Nuclear Information System (INIS)

    Kralova, K.; Sersen, F.; Gasparova, R.; Lacova, M.

    1998-01-01

    The effects of 3-R 2 -2[2-(6-R 1 -chromone-3-yl)ethenyl]benzothiazolium halides (CBH) on photosynthetic electron transport in spinach chloroplasts and in the legal suspension of Chlorella vulgaris were investigated. Using EPR spectroscopy it was confirmed that these compounds containing in their molecules two heterocyclic skeletons, namely benzothiazole and chromone, interact with the intermediate D + , corresponding to the tyrosine radical Tyr D situated in D 2 protein on the donor side of photosystem 2. Consequently, higher concentrations of CBH inhibited oxygen evolution rate in Chlorella vulgaris and the inhibitory effectiveness depended on the lipophilicity of the of the compound. (authors)

  2. The sporulation of the green alga Ulva prolifera is controlled by changes in photosynthetic electron transport chain.

    Science.gov (United States)

    Wang, Hui; Lin, Apeng; Gu, Wenhui; Huan, Li; Gao, Shan; Wang, Guangce

    2016-04-22

    Sporulation and spore release are essential phases of the life cycle in algae and land plants. Ulva prolifera, which is an ideal organism for studying sporulation and spore release, was used as the experimental material in the present study. The determination of photosynthetic parameters, combined with microscopic observation, treatment with photosynthetic inhibitors, limitation of carbon acquisition, and protein mass spectrometry, was employed in this experiment. Cycle electron transport (CEF) was found enhanced at the onset of sporangia formation. The inhibition effect of dibromothymoquinone (DBMIB) towards sporulation was always strong during the sporulation process whereas the inhibition effect of 3-(3',4'-dichlorophenyl)-1,1-dimethylurea (DCMU) was continuously declined accompanied with the progress of sporulation. The changes of photosynthesis resulted from the limitation of CO2 acquisition could stimulate sporulation onset. Quantitative protein analysis showed that enzymes involved in carbon fixation, including RUBISCO and pyruvate orthophosphate dikinase, declined during sporogenesis, while proteins involved in sporulation, including tubulin and centrin, increased. These results suggest that enhanced cyclic electron flow (CEF) and oxidation of the plastoquinone pool are essential for sporangia formation onset, and changes in photosynthetic electron transport chain have significant impacts on sporulation of the green algae.

  3. Application of heat stress in situ demonstrates a protective role of irradiation on photosynthetic performance in alpine plants.

    Science.gov (United States)

    Buchner, Othmar; Stoll, Magdalena; Karadar, Matthias; Kranner, Ilse; Neuner, Gilbert

    2015-04-01

    The impact of sublethal heat on photosynthetic performance, photosynthetic pigments and free radical scavenging activity was examined in three high mountain species, Rhododendron ferrugineum, Senecio incanus and Ranunculus glacialis using controlled in situ applications of heat stress, both in darkness and under natural solar irradiation. Heat treatments applied in the dark reversibly reduced photosynthetic performance and the maximum quantum efficiency of photosystem II (Fv /Fm), which remained impeded for several days when plants were exposed to natural light conditions subsequently to the heat treatment. In contrast, plants exposed to heat stress under natural irradiation were able to tolerate and recover from heat stress more readily. The critical temperature threshold for chlorophyll fluorescence was higher under illumination (Tc (')) than in the dark (Tc). Heat stress caused a significant de-epoxidation of the xanthophyll cycle pigments both in the light and in the dark conditions. Total free radical scavenging activity was highest when heat stress was applied in the dark. This study demonstrates that, in the European Alps, heat waves can temporarily have a negative impact on photosynthesis and, importantly, that results obtained from experiments performed in darkness and/or on detached plant material may not reliably predict the impact of heat stress under field conditions. © 2014 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.

  4. Growth and Photosynthetic Pigments Accumulation of Jute Mallow (Corchorus olitorius Linn. in Response to Different Levels of Magnesium Application

    Directory of Open Access Journals (Sweden)

    Ezekiel Dare OLOWOLAJU

    2017-06-01

    Full Text Available The hereby study investigated the effect of Magnesium application at different levels on the morphological parameters and photosynthetic pigment accumulation of Corchorus olitorius. Seeds of C. olitorius were utilized in the experiment. These seeds were sown in 2 big bowls and were supplied with 200 ml of water every day until they were fully established. After three weeks of sowing, the seedlings were transplanted into plastic pots. The treatments were: distilled water (control; nutrient solution in which the concentration of Magnesium was increased by the factor of 5 (N5, nutrient solution in which the concentration of Magnesium was increased by the factor of 10 (N10 and nutrient solution lacking Magnesium source (NMg. The seedlings were then divided into 4 regimes, with each regime containing each treatment. From the results obtained, it was observed that there was a significant effect at (P≥0.05 on the Corchorus olitorius growth parameters and photosynthetic pigment accumulation among the treatments. There was an increase in the shoot height, number of leaves, number of flowers, leaf area and the photosynthetic pigment accumulation in the seedlings treated with magnesium increased by the factor of 5 (N5 than by other treatments. The control recorded the lowest values for these parameters. It can be concluded that for an optimum growth of Corchorus olitorius, it can be inferred that the plant can do well in nutrient solution having Magnesium source (at moderate level.

  5. Acute toxicity of excess mercury on the photosynthetic performance of cyanobacterium, S. platensis--assessment by chlorophyll fluorescence analysis.

    Science.gov (United States)

    Lu, C M; Chau, C W; Zhang, J H

    2000-07-01

    Measurement of chlorophyll fluorescence has been shown to be a rapid, non-invasive, and reliable method to assess photosynthetic performance in a changing environment. In this study, acute toxicity of excess Hg on the photosynthetic performance of the cyanobacterium S. platensis, was investigated by use of chlorophyll fluorescence analysis after cells were exposed to excess Hg (up to 20 microM) for 2 h. The results determined from the fast fluorescence kinetics showed that Hg induced a significant increase in the proportion of the Q(B)-non-reducing PSII reaction centers. The fluorescence parameters measured under the steady state of photosynthesis demonstrated that the increase of Hg concentration led to a decrease in the maximal efficiency of PSII photochemistry, the efficiency of excitation energy capture by the open PSII reaction centers, and the quantum yield of PSII electron transport. Mercury also resulted in a decrease in the coefficients of photochemical and non-photochemical quenching. Mercury may have an acute toxicity on cyanobacteria by inhibiting the quantum yield of photosynthesis sensitively and rapidly. Such changes occurred before any other visible damages that may be evaluated by other conventional measurements. Our results also demonstrated that chlorophyll fluorescence analysis can be used as a useful physiological tool to assess early stages of change in photosynthetic performance of algae in response to heavy metal pollution.

  6. Seagrass canopy photosynthetic response is a function of canopy density and light environment: a model for Amphibolis griffithii.

    Science.gov (United States)

    Hedley, John D; McMahon, Kathryn; Fearns, Peter

    2014-01-01

    A three-dimensional computer model of canopies of the seagrass Amphibolis griffithii was used to investigate the consequences of variations in canopy structure and benthic light environment on leaf-level photosynthetic saturation state. The model was constructed using empirical data of plant morphometrics from a previously conducted shading experiment and validated well to in-situ data on light attenuation in canopies of different densities. Using published values of the leaf-level saturating irradiance for photosynthesis, results show that the interaction of canopy density and canopy-scale photosynthetic response is complex and non-linear, due to the combination of self-shading and the non-linearity of photosynthesis versus irradiance (P-I) curves near saturating irradiance. Therefore studies of light limitation in seagrasses should consider variation in canopy structure and density. Based on empirical work, we propose a number of possible measures for canopy scale photosynthetic response that can be plotted to yield isoclines in the space of canopy density and light environment. These plots can be used to interpret the significance of canopy changes induced as a response to decreases in the benthic light environment: in some cases canopy thinning can lead to an equivalent leaf level light environment, in others physiological changes may also be required but these alone may be inadequate for canopy survival. By providing insight to these processes the methods developed here could be a valuable management tool for seagrass conservation during dredging or other coastal developments.

  7. Seagrass canopy photosynthetic response is a function of canopy density and light environment: a model for Amphibolis griffithii.

    Directory of Open Access Journals (Sweden)

    John D Hedley

    Full Text Available A three-dimensional computer model of canopies of the seagrass Amphibolis griffithii was used to investigate the consequences of variations in canopy structure and benthic light environment on leaf-level photosynthetic saturation state. The model was constructed using empirical data of plant morphometrics from a previously conducted shading experiment and validated well to in-situ data on light attenuation in canopies of different densities. Using published values of the leaf-level saturating irradiance for photosynthesis, results show that the interaction of canopy density and canopy-scale photosynthetic response is complex and non-linear, due to the combination of self-shading and the non-linearity of photosynthesis versus irradiance (P-I curves near saturating irradiance. Therefore studies of light limitation in seagrasses should consider variation in canopy structure and density. Based on empirical work, we propose a number of possible measures for canopy scale photosynthetic response that can be plotted to yield isoclines in the space of canopy density and light environment. These plots can be used to interpret the significance of canopy changes induced as a response to decreases in the benthic light environment: in some cases canopy thinning can lead to an equivalent leaf level light environment, in others physiological changes may also be required but these alone may be inadequate for canopy survival. By providing insight to these processes the methods developed here could be a valuable management tool for seagrass conservation during dredging or other coastal developments.

  8. [Impact of atmospheric total suspended particulate pollution on photosynthetic parameters of street mango trees in Xiamen City].

    Science.gov (United States)

    Yu, Yu-xian; Chen, Jin-sheng; Ren, Yin; Li, Fang-yi; Cui, Sheng-hui

    2010-05-01

    With the development of urbanization, total suspended particulate (TSP) pollution is getting serious, and the normal physiological processes of urban vegetation are profoundly affected while adsorbing and purifying the particulates. In this study, four areas were selected, i.e., Tingxi reservoir (clean control area), Xiamen University (cultural and educational area), Xianyue (business area), and Haicang (industrial area), with their atmospheric TSP concentrations and the photosynthetic parameters of street Mango (Mangifera indica) trees monitored in April and May, 2009. The daily average concentration of TSP in Tingxi, Xiamen University, Xianyue, and Haicang was 0.061, 0.113, 0.120 and 0.205 mg x m(-3), respectively, and the impact of TSP stress on M. indica was in the sequence of Haicang > Xianyue > Xiamen University > Tingxi. TSP pollution negatively affected the net photosynthetic rate, stomatal conductance, and transpiration rate of M. indica, and induced intercellular CO2 concentration changed significantly. High TSP concentration could cause the decline of net photosynthetic rate via stomatal limitation.

  9. Temperature responses of photosynthetic capacity parameters were not affected by foliar nitrogen content in mature Pinus sylvestris.

    Science.gov (United States)

    Tarvainen, Lasse; Lutz, Martina; Räntfors, Mats; Näsholm, Torgny; Wallin, Göran

    2018-03-01

    A key weakness in current Earth System Models is the representation of thermal acclimation of photosynthesis in response to changes in growth temperatures. Previous studies in boreal and temperate ecosystems have shown leaf-scale photosynthetic capacity parameters, the maximum rates of carboxylation (V cmax ) and electron transport (J max ), to be positively correlated with foliar nitrogen (N) content at a given reference temperature. It is also known that V cmax and J max exhibit temperature optima that are affected by various environmental factors and, further, that N partitioning among the foliar photosynthetic pools is affected by N availability. However, despite the strong recent anthropogenic influence on atmospheric temperatures and N deposition to forests, little is known about the role of foliar N contents in controlling the photosynthetic temperature responses. In this study, we investigated the temperature dependencies of V cmax and J max in 1-year-old needles of mature boreal Pinus sylvestris (Scots pine) trees growing under low and high N availabilities in northern Sweden. We found that needle N status did not significantly affect the temperature responses of V cmax or J max when the responses were fitted to a peaked function. If such N insensitivity is a common tree trait it will simplify the interpretation of the results from gradient and multi-species studies, which commonly use sites with differing N availabilities, on temperature acclimation of photosynthetic capacity. Moreover, it will simplify modeling efforts aimed at understanding future carbon uptake by precluding the need to adjust the shape of the temperature response curves to variation in N availability. © 2017 Scandinavian Plant Physiology Society.

  10. Photosynthetic, morphological, and reproductive variations in Cypripedium tibeticum in relation to different light regimes in a subalpine forest.

    Directory of Open Access Journals (Sweden)

    Bao-Qiang Zheng

    Full Text Available Cypripedium tibeticum, a subalpine orchid species, inhabits various habitats of subalpine forests, mainly including the forest edge (FE, forest gap (FG, and understory (UST, which have significantly different light intensities (FE > FG > UST. However, the ecological and physiological influences caused by different light regimes in this species are still poorly understood. In the present study, photosynthetic, morphological, and reproductive characteristics were comprehensively studied in plants of C. tibeticum grown in three types of habitats. The photosynthetic capacities, such as the net photosynthetic rate, light-saturated photosynthesis (Pmax, and dry mass per unit leaf area (LMA, were higher in FE and FG than in UST according to light availability. Compared with FG, the populations in FE and UST suffer from excessively strong and inadequate radiation, respectively, which was further corroborated by the low Fv/Fm in FE and high apparent quantum yield (AQY in FG. The leaves of the orchids had various proportions of constituents, such as the leaf area, thickness and (or epidermal hair, to reduce damage from high radiation (including ultraviolet-b radiation in FE and capture more light in FG and UST. Although the flower rate (FR was positively correlated to both Pmax and the daily mean PAR, fruit-set only occurred in the populations in FG. The failures in FE and UST might be ascribed to changes in the floral functional structure and low biomass accumulation, respectively. Moreover, analysis of the demographic statistics showed that FG was an advantageous habitat for the orchid. Thus, C. tibeticum reacted to photosynthetic and morphological changes to adapt to different subalpine forest habitats, and neither full (under FE nor low (UST illumination was favorable for population expansion. These findings could serve as a guide for the protection and reintroduction of C. tibeticum and emphasize the importance of specific habitats for Cypripedium

  11. Photoinhibition-like damage to the photosynthetic apparatus in plant leaves induced by submergence treatment in the dark.

    Directory of Open Access Journals (Sweden)

    Xingli Fan

    Full Text Available Submergence is a common type of environmental stress for plants. It hampers survival and decreases crop yield, mainly by inhibiting plant photosynthesis. The inhibition of photosynthesis and photochemical efficiency by submergence is primarily due to leaf senescence and excess excitation energy, caused by signals from hypoxic roots and inhibition of gas exchange, respectively. However, the influence of mere leaf-submergence on the photosynthetic apparatus is currently unknown. Therefore, we studied the photosynthetic apparatus in detached leaves from four plant species under dark-submergence treatment (DST, without influence from roots and light. Results showed that the donor and acceptor sides, the reaction center of photosystem II (PSII and photosystem I (PSI in leaves were significantly damaged after 36 h of DST. This is a photoinhibition-like phenomenon similar to the photoinhibition induced by high light, as further indicated by the degradation of PsaA and D1, the core proteins of PSI and PSII. In contrast to previous research, the chlorophyll content remained unchanged and the H2O2 concentration did not increase in the leaves, implying that the damage to the photosynthetic apparatus was not caused by senescence or over-accumulation of reactive oxygen species (ROS. DST-induced damage to the photosynthetic apparatus was aggravated by increasing treatment temperature. This type of damage also occurred in the anaerobic environment (N2 without water, and could be eliminated or restored by supplying air to the water during or after DST. Our results demonstrate that DST-induced damage was caused by the hypoxic environment. The mechanism by which DST induces the photoinhibition-like damage is discussed below.

  12. Photosynthetic, morphological, and reproductive variations in Cypripedium tibeticum in relation to different light regimes in a subalpine forest.

    Science.gov (United States)

    Zheng, Bao-Qiang; Zou, Long-Hai; Li, Kui; Wan, Xiao; Wang, Yan

    2017-01-01

    Cypripedium tibeticum, a subalpine orchid species, inhabits various habitats of subalpine forests, mainly including the forest edge (FE), forest gap (FG), and understory (UST), which have significantly different light intensities (FE > FG > UST). However, the ecological and physiological influences caused by different light regimes in this species are still poorly understood. In the present study, photosynthetic, morphological, and reproductive characteristics were comprehensively studied in plants of C. tibeticum grown in three types of habitats. The photosynthetic capacities, such as the net photosynthetic rate, light-saturated photosynthesis (Pmax), and dry mass per unit leaf area (LMA), were higher in FE and FG than in UST according to light availability. Compared with FG, the populations in FE and UST suffer from excessively strong and inadequate radiation, respectively, which was further corroborated by the low Fv/Fm in FE and high apparent quantum yield (AQY) in FG. The leaves of the orchids had various proportions of constituents, such as the leaf area, thickness and (or) epidermal hair, to reduce damage from high radiation (including ultraviolet-b radiation) in FE and capture more light in FG and UST. Although the flower rate (FR) was positively correlated to both Pmax and the daily mean PAR, fruit-set only occurred in the populations in FG. The failures in FE and UST might be ascribed to changes in the floral functional structure and low biomass accumulation, respectively. Moreover, analysis of the demographic statistics showed that FG was an advantageous habitat for the orchid. Thus, C. tibeticum reacted to photosynthetic and morphological changes to adapt to different subalpine forest habitats, and neither full (under FE) nor low (UST) illumination was favorable for population expansion. These findings could serve as a guide for the protection and reintroduction of C. tibeticum and emphasize the importance of specific habitats for Cypripedium spp.

  13. Effect of temperature and light intensity on growth and photosynthetic activity of Chlamydomonas Reinhardtii

    International Nuclear Information System (INIS)

    Alfonsel, M.; Fernandez Gonzalez, J.

    1986-01-01

    The effect of five temperatures (15, 20, 25, 30 and 35 0 C) and two levels of illumination on growth and photosynthetic activity of Chlamydomonas reinhardtii has been studied. The growth of the cultures was evaluated by optical density. Photosynthetic activity has been carried out studying either the assimilation rate of CO 2 labelled with C 14 or the oxygen evolution by means of polarographic measurements. The maximum photosynthetic rate has been obtained at 25 0 C for the lower lavel of illumination (2400 lux) and at 35 0 C for the higher one (13200 lux). These results suggest an interacton of temperature and illumination on photosynthetic activity. (author)

  14. Reductive evolution of chloroplasts in non-photosynthetic plants, algae and protists.

    Science.gov (United States)

    Hadariová, Lucia; Vesteg, Matej; Hampl, Vladimír; Krajčovič, Juraj

    2018-04-01

    Chloroplasts are generally known as eukaryotic organelles whose main function is photosynthesis. They perform other functions, however, such as synthesizing isoprenoids, fatty acids, heme, iron sulphur clusters and other essential compounds. In non-photosynthetic lineages that possess plastids, the chloroplast genomes have been reduced and most (or all) photosynthetic genes have been lost. Consequently, non-photosynthetic plastids have also been reduced structurally. Some of these non-photosynthetic or "cryptic" plastids were overlooked or unrecognized for decades. The number of complete plastid genome sequences and/or transcriptomes from non-photosynthetic taxa possessing plastids is rapidly increasing, thus allowing prediction of the functions of non-photosynthetic plastids in various eukaryotic lineages. In some non-photosynthetic eukaryotes with photosynthetic ancestors, no traces of plastid genomes or of plastids have been found, suggesting that they have lost the genomes or plastids completely. This review summarizes current knowledge of non-photosynthetic plastids, their genomes, structures and potential functions in free-living and parasitic plants, algae and protists. We introduce a model for the order of plastid gene losses which combines models proposed earlier for land plants with the patterns of gene retention and loss observed in protists. The rare cases of plastid genome loss and complete plastid loss are also discussed.

  15. [Effects of reduced solar radiation on winter wheat flag leaf net photosynthetic rate].

    Science.gov (United States)

    Zheng, You-Fei; Ni, Yan-Li; Mai, Bo-Ru; Wu, Rong-Jun; Feng, Yan; Sun, Jian; Li, Jian; Xu, Jing-Xin

    2011-06-01

    Taking winter wheat Triticum aestivum L. (cv. Yangmai 13) as test material, a field experiment was conducted in Nanjing City to study the effects of simulated reduced solar radiation on the diurnal variation of winter wheat flag leaf photosynthetic rate and the main affecting factors. Five treatments were installed, i. e., 15% (T15), 20% (T20) , 40% (T40), 60% (T60), and 100% (CK) of total incident solar radiation. Reduced solar irradiance increased the chlorophyll and lutein contents significantly, but decreased the net photosynthetic rate (Pn). Under different solar irradiance, the diurnal variation of Pn had greater difference, and the daily maximum Pn was in the order of CK > T60 > T40 > T 20 > T15. In CK, the Pn exhibited a double peak diurnal curve; while in the other four treatments, the Pn showed a single peak curve, and the peak was lagged behind that of CK. Correlation analysis showed that reduced solar irradiance was the main factor affecting the diurnal variation of Pn, but the physiological parameters also played important roles in determining the diurnal variation of Pn. In treatments T60 and T40, the photosynthesis active radiation (PAR), leaf temperature (T1) , stomatal conductance (Gs) , and transpiration rate (Tr) were significantly positively correlated with Pn, suggesting their positive effects on Pn. The intercellular CO2 concentration (Ci) and stomatal limitation (Ls) had significant negative correlations with Pn in treatments T60 and T40 but significant positive correlations with Pn in treatments T20 and T15, implying that the Ci and Ls had negative (or positive) effects on Pn when the solar irradiance was higher (or lower) than 40% of incident solar irradiance.

  16. Global Ocean Phytoplankton

    Science.gov (United States)

    Franz, B. A.; Behrenfeld, M. J.; Siegel, D. A.; Werdell, P. J.

    2014-01-01

    Marine phytoplankton are responsible for roughly half the net primary production (NPP) on Earth, fixing atmospheric CO2 into food that fuels global ocean ecosystems and drives the ocean's biogeochemical cycles. Phytoplankton growth is highly sensitive to variations in ocean physical properties, such as upper ocean stratification and light availability within this mixed layer. Satellite ocean color sensors, such as the Sea-viewing Wide Field-of-view Sensor (SeaWiFS; McClain 2009) and Moderate Resolution Imaging Spectroradiometer (MODIS; Esaias 1998), provide observations of sufficient frequency and geographic coverage to globally monitor physically-driven changes in phytoplankton distributions. In practice, ocean color sensors retrieve the spectral distribution of visible solar radiation reflected upward from beneath the ocean surface, which can then be related to changes in the photosynthetic phytoplankton pigment, chlorophyll- a (Chla; measured in mg m-3). Here, global Chla data for 2013 are evaluated within the context of the 16-year continuous record provided through the combined observations of SeaWiFS (1997-2010) and MODIS on Aqua (MODISA; 2002-present). Ocean color measurements from the recently launched Visible and Infrared Imaging Radiometer Suite (VIIRS; 2011-present) are also considered, but results suggest that the temporal calibration of the VIIRS sensor is not yet sufficiently stable for quantitative global change studies. All MODISA (version 2013.1), SeaWiFS (version 2010.0), and VIIRS (version 2013.1) data presented here were produced by NASA using consistent Chla algorithms.

  17. Climatic driving forces in inter-annual variation of global FPAR

    Science.gov (United States)

    Peng, Dailiang; Liu, Liangyun; Yang, Xiaohua; Zhou, Bin

    2012-09-01

    Fraction of Absorbed Photosynthetically Active Radiation (FPAR) characterizes vegetation canopy functioning and its energy absorption capacity. In this paper, we focus on climatic driving forces in inter-annual variation of global FPAR from 1982 to 2006 by Global Historical Climatology Network (GHCN-Monthly) data. Using FPAR-Simple Ratio Vegetation Index (SR) relationship, Advanced Very High Resolution Radiometer (AVHRR) Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI) was used to estimate FPAR at the global scale. The correlation between inter-annual variation of FPAR and temperature, precipitation derived from GHCN-Monthly was examined, during the periods of March-May (MAM), June-August (JJA), September-November (SON), and December-February (DJF) over from 1982 to 2006. The analysis of climatic influence on global FPAR revealed the significant correlation with temperature and precipitation in some meteorological stations area, and a more significant correlation with precipitation was found than which with temperature. Some stations in the regions between 30° N and 60° N and around 30° S in South America, where the annual FPAR variation showed a significant positive correlation with temperature (P forest of Africa and Amazon during the dry season of JJA and SON.

  18. Composition and functional property of photosynthetic pigments under circadian rhythm in the cyanobacterium Spirulina platensis.

    Science.gov (United States)

    Kumar, Deepak; Kannaujiya, Vinod K; Richa; Pathak, Jainendra; Sundaram, Shanthy; Sinha, Rajeshwar P

    2018-05-01

    Circadian rhythm is an important endogenous biological signal for sustainable growth and development of cyanobacteria in natural ecosystems. Circadian effects of photosynthetically active radiation (PAR), ultraviolet-A (UV-A) and ultraviolet-B (UV-B) radiations on pigment composition have been studied in the cyanobacterium Spirulina platensis under light (L)/dark (D) oscillation with a combination of 4/20, 8/16, 12/12, 16/8, 20/4 and 24/24 h time duration. Circadian exposure of PAR + UV-A (PA) and PAR + UV-A + UV-B (PAB) showed more than twofold decline in Chl a, total protein and phycocyanin (PC) in light phase and significant recovery was achieved in dark phase. The fluorescence emission wavelength of PC was shifted towards lower wavelengths in the light phase of PAB in comparison to P and PA whereas the same wavelength was retrieved in the dark phase. The production of free radicals was accelerated twofold in the light phase (24 h L) whereas the same was retrieved to the level of control during the dark phase. Oxidatively induced damage was alleviated by antioxidative enzymes such as catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and ascorbate peroxidase (APX) in the light phase (0-24-h L) whereas the dark phase showed significant inhibition of the same enzymes. Similar characteristic inhibition of free radicals and recovery of PC was observed inside cellular filament after circadian rhythm of 24/24 h (L/D). Circadian exposure of P, PA and PAB significantly altered the synthesis and recovery of pigments that could be crucial for optimization and sustainable production of photosynthetic products for human welfare.

  19. Towards quantification of vibronic coupling in photosynthetic antenna complexes

    Energy Technology Data Exchange (ETDEWEB)

    Singh, V. P.; Westberg, M.; Wang, C.; Gellen, T.; Engel, G. S., E-mail: gsengel@uchicago.edu [Department of Chemistry, The James Franck Institute and The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637 (United States); Dahlberg, P. D. [Graduate Program in the Biophysical Sciences, The James Franck Institute and The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637 (United States); Gardiner, A. T.; Cogdell, R. J. [Department of Botany, Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, Scotland (United Kingdom)

    2015-06-07

    Photosynthetic antenna complexes harvest sunlight and efficiently transport energy to the reaction center where charge separation powers biochemical energy storage. The discovery of existence of long lived quantum coherence during energy transfer has sparked the discussion on the role of quantum coherence on the energy transfer efficiency. Early works assigned observed coherences to electronic states, and theoretical studies showed that electronic coherences could affect energy transfer efficiency—by either enhancing or suppressing transfer. However, the nature of coherences has been fiercely debated as coherences only report the energy gap between the states that generate coherence signals. Recent works have suggested that either the coherences observed in photosynthetic antenna complexes arise from vibrational wave packets on the ground state or, alternatively, coherences arise from mixed electronic and vibrational states. Understanding origin of coherences is important for designing molecules for efficient light harvesting. Here, we give a direct experimental observation from a mutant of LH2, which does not have B800 chromophores, to distinguish between electronic, vibrational, and vibronic coherence. We also present a minimal theoretical model to characterize the coherences both in the two limiting cases of purely vibrational and purely electronic coherence as well as in the intermediate, vibronic regime.

  20. Managing the cellular redox hub in photosynthetic organisms.

    Science.gov (United States)

    Foyer, Christine H; Noctor, Graham

    2012-02-01

    Light-driven redox chemistry is a powerful source of redox signals that has a decisive input into transcriptional control within the cell nucleus. Like photosynthetic electron transport pathways, the respiratory electron transport chain exerts a profound control over gene function, in order to balance energy (reductant and ATP) supply with demand, while preventing excessive over-reduction or over-oxidation that would be adversely affect metabolism. Photosynthetic and respiratory redox chemistries are not merely housekeeping processes but they exert a controlling influence over every aspect of plant biology, participating in the control of gene transcription and translation, post-translational modifications and the regulation of assimilatory reactions, assimilate partitioning and export. The number of processes influenced by redox controls and signals continues to increase as do the components that are recognized participants in the associated signalling pathways. A step change in our understanding of the overall importance of the cellular redox hub to plant cells has occurred in recent years as the complexity of the management of the cellular redox hub in relation to metabolic triggers and environmental cues has been elucidated. This special issue describes aspects of redox regulation and signalling at the cutting edge of current research in this dynamic and rapidly expanding field. © 2011 Blackwell Publishing Ltd.

  1. Phylogeny and photosynthetic pathway distribution in Anticharis Endl. (Scrophulariaceae).

    Science.gov (United States)

    Khoshravesh, Roxana; Hossein, Akhani; Sage, Tammy L; Nordenstam, Bertil; Sage, Rowan F

    2012-09-01

    C(4) photosynthesis independently evolved >62 times, with the majority of origins within 16 dicot families. One origin occurs in the poorly studied genus Anticharis Endl. (Scrophulariaceae), which consists of ~10 species from arid regions of Africa and southwest Asia. Here, the photosynthetic pathway of 10 Anticharis species and one species from each of the sister genera Aptosimum and Peliostomum was identified using carbon isotope ratios (δ(13)C). The photosynthetic pathway was then mapped onto an internal transcribed spacer (ITS) phylogeny of Anticharis and its sister genera. Leaf anatomy was examined for nine Anticharis species and plants from Aptosimum and Peliostomum. Leaf ultrastructure, gas exchange, and enzyme distributions were assessed in Anticharis glandulosa collected in SE Iran. The results demonstrate that C(3) photosynthesis is the ancestral condition, with C(4) photosynthesis occurring in one clade containing four species. C(4) Anticharis species exhibit the atriplicoid type of C(4) leaf anatomy and the NAD-malic enzyme biochemical subtype. Six Anticharis species had C(3) or C(3)-C(4) δ(13)C values and branched at phylogenetic nodes that were sister to the C(4) clade. The rest of Anticharis species had enlarged bundle sheath cells, close vein spacing, and clusters of chloroplasts along the centripetal (inner) bundle sheath walls. These traits indicate that basal-branching Anticharis species are evolutionary intermediates between the C(3) and C(4) conditions. Anticharis appears to be an important new group in which to study the dynamics of C(4) evolution.

  2. Enzymes involved in organellar DNA replication in photosynthetic eukaryotes.

    Science.gov (United States)

    Moriyama, Takashi; Sato, Naoki

    2014-01-01

    Plastids and mitochondria possess their own genomes. Although the replication mechanisms of these organellar genomes remain unclear in photosynthetic eukaryotes, several organelle-localized enzymes related to genome replication, including DNA polymerase, DNA primase, DNA helicase, DNA topoisomerase, single-stranded DNA maintenance protein, DNA ligase, primer removal enzyme, and several DNA recombination-related enzymes, have been identified. In the reference Eudicot plant Arabidopsis thaliana, the replication-related enzymes of plastids and mitochondria are similar because many of them are dual targeted to both organelles, whereas in the red alga Cyanidioschyzon merolae, plastids and mitochondria contain different replication machinery components. The enzymes involved in organellar genome replication in green plants and red algae were derived from different origins, including proteobacterial, cyanobacterial, and eukaryotic lineages. In the present review, we summarize the available data for enzymes related to organellar genome replication in green plants and red algae. In addition, based on the type and distribution of replication enzymes in photosynthetic eukaryotes, we discuss the transitional history of replication enzymes in the organelles of plants.

  3. Biomaterials based on photosynthetic membranes as potential sensors for herbicides.

    Science.gov (United States)

    Ventrella, Andrea; Catucci, Lucia; Placido, Tiziana; Longobardi, Francesco; Agostiano, Angela

    2011-08-15

    In this study, ultrathin film multilayers of Photosystem II-enriched photosynthetic membranes (BBY) were prepared and immobilized on quartz substrates by means of a Layer by Layer procedure exploiting electrostatic interactions with poly(ethylenimine) as polyelectrolyte. The biomaterials thus obtained were characterized by means of optical techniques and Atomic Force Microscopy, highlighting the fact that the Layer by Layer approach allowed the BBYs to be immobilized with satisfactory results. The activity of these hybrid materials was evaluated by means of optical assays based on the Hill Reaction, indicating that the biosamples, which preserved about 65% of their original activity even ten weeks after preparation, were both stable and active. Furthermore, an investigation of the biochips' sensitivity to the herbicide terbutryn, as a model analyte, gave interesting results: inhibition of photosynthetic activity was observed at terbutryn concentrations higher than 10(-7)M, thus evidencing the potential of such biomaterials in the environmental biosensor field. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Dynamic reorganization of photosynthetic supercomplexes during environmental acclimation

    Directory of Open Access Journals (Sweden)

    Jun eMinagawa

    2013-12-01

    Full Text Available Plants and algae have acquired the ability to acclimate to ever-changing environments in order to survive. During photosynthesis, light energy is converted by several membrane protein supercomplexes into electrochemical energy, which is eventually used to assimilate CO2. The efficiency of photosynthesis is modulated by many environmental factors such as quality and quantity of light, temperature, drought, and CO2 concentration, among others. Accumulating evidence indicates that photosynthetic supercomplexes undergo supramolecular reorganization within a short timeframe during acclimation to an environmental change. This reorganization includes state transitions that balance the excitation of photosystem I and II by shuttling peripheral antenna proteins between the two, thermal energy dissipation that occurs at energy-quenching sites within the light-harvesting antenna generated for negative feedback when excess light is absorbed, and cyclic electron flow that is facilitated between photosystem I and the cytochrome bf complex when cells demand more ATP and/or need to activate energy dissipation. This review will highlight the recent findings regarding these environmental acclimation events in model organisms with particular attention to the unicellular green alga C. reinhardtii and with reference to the vascular plant A. thaliana, which offers a glimpse into the dynamic behavior of photosynthetic machineries in nature.

  5. Significant Tsunami Events

    Science.gov (United States)

    Dunbar, P. K.; Furtney, M.; McLean, S. J.; Sweeney, A. D.

    2014-12-01

    Tsunamis have inflicted death and destruction on the coastlines of the world throughout history. The occurrence of tsunamis and the resulting effects have been collected and studied as far back as the second millennium B.C. The knowledge gained from cataloging and examining these events has led to significant changes in our understanding of tsunamis, tsunami sources, and methods to mitigate the effects of tsunamis. The most significant, not surprisingly, are often the most devastating, such as the 2011 Tohoku, Japan earthquake and tsunami. The goal of this poster is to give a brief overview of the occurrence of tsunamis and then focus specifically on several significant tsunamis. There are various criteria to determine the most significant tsunamis: the number of deaths, amount of damage, maximum runup height, had a major impact on tsunami science or policy, etc. As a result, descriptions will include some of the most costly (2011 Tohoku, Japan), the most deadly (2004 Sumatra, 1883 Krakatau), and the highest runup ever observed (1958 Lituya Bay, Alaska). The discovery of the Cascadia subduction zone as the source of the 1700 Japanese "Orphan" tsunami and a future tsunami threat to the U.S. northwest coast, contributed to the decision to form the U.S. National Tsunami Hazard Mitigation Program. The great Lisbon earthquake of 1755 marked the beginning of the modern era of seismology. Knowledge gained from the 1964 Alaska earthquake and tsunami helped confirm the theory of plate tectonics. The 1946 Alaska, 1952 Kuril Islands, 1960 Chile, 1964 Alaska, and the 2004 Banda Aceh, tsunamis all resulted in warning centers or systems being established.The data descriptions on this poster were extracted from NOAA's National Geophysical Data Center (NGDC) global historical tsunami database. Additional information about these tsunamis, as well as water level data can be found by accessing the NGDC website www.ngdc.noaa.gov/hazard/

  6. Combining machine learning and remotely sensed bandratios to investigate chlorophyll content and photosynthetic processes

    Science.gov (United States)

    Gholizadeh, Hamed

    Photosynthesis in aquatic and terrestrial ecosystems is the key component of the food chain and the most important driver of the global carbon cycle. Therefore, estimation of photosynthesis at large spatial scales is of great scientific importance and can only practically be achieved by remote sensing data and techniques. In this dissertation, remotely sensed information and techniques, as well as field measurements, are used to improve current approaches of assessing photosynthetic processes. More specifically, three topics are the focus here: (1) investigating the application of spectral vegetation indices as proxies for terrestrial chlorophyll in a mangrove ecosystem, (2) evaluating and improving one of the most common empirical ocean-color algorithms (OC4), and (3) developing an improved approach based on sunlit-to-shaded scaled photochemical reflectance index (sPRI) ratios for detecting drought signals in a deciduous forest at eastern United States. The results indicated that although the green normalized difference vegetation index (GNDVI) is an efficient proxy for terrestrial chlorophyll content, there are opportunities to improve the performance of vegetation indices by optimizing the band weights. In regards to the second topic, we concluded that the parameters of the OC4 algorithm and similar empirical models should be tuned regionally and the addition of sea-surface temperature makes the global ocean-color approaches more valid. Results obtained from the third topic showed that considering shaded and sunlit portions of the canopy (i.e., two-leaf models instead of single big leaf models) and taking into account the divergent stomatal behavior of the species (i.e. isohydric and anisohydric) can improve the capability of sPRI in detecting drought. In addition to investigating the photosynthetic processes, the other common theme of the three research topics is the evaluation of "off- the-shelf" solutions to remote-sensing problems. Although widely used

  7. FEATURES OF PHYSIOLOGICAL AND PHOTOSYNTHETIC ACTIVITY OF MAIZE PLANTS AT USING NON-TRADITIONAL ORGANIC FERTILIZERS

    Directory of Open Access Journals (Sweden)

    A. Kojuhov

    2012-07-01

    Full Text Available The use of fertilizers in cultivation of crops is an objective necessity. However, their use has a negative impact on environment and especially on the soil polluting it with heavy metals. Organic fertilizers can significantly improve physical and chemical soil properties and increase its fertility. In connection with deficiency of manure particular interest represents using of waste as non-conventional fertilizers, in particular waste of alcohol production. Using of high-dose alcohol stillage stronger growth processes and number of leaves, which leads to an increase of maize photosynthetic activity and productivity. Maximum formation of green mass was observed in variant with a dose of making alcohol stillage 40 m3/ha during vegetation.

  8. Transmittance of young Norway spruce stand canopy for photosynthetically active radiation during the growing season

    International Nuclear Information System (INIS)

    Markova, I.; Kubasek, J.

    2013-01-01

    Analysis of transmittance of young Norway spruce stand canopy for photosynthetically active radiation (PAR) was made at the study site of Bily Kriz (the Moravian-Silesian Beskids Mts., the Czech Republic) at different sky conditions during the growing season in 2010. For the description of PAR transmittance different phenological phases of the spruce stand development in clear and overcast days were chosen. The mean daily PAR transmittance of the spruce canopy was significantly higher in overcast days compared with clear ones. Diffuse PAR thus penetrated into lower parts of the canopy more efficiently than direct one. PAR transmittance of young Norway spruce stand canopy was different in individual phenological phases of the spruce stand canopy which was caused by changes in the stand structure during the growing season. Thus monitoring of transmittance of young Norway spruce stand canopy for PAR can help to describe the development of spruce stand canopy

  9. PHOTOSYNTHETIC PIGMENT AND GENETIC DIFFERENCES BETWEEN TWO SOUTHERN OCEAN MORPHOTYPES OF EMILIANIA HUXLEYI (HAPTOPHYTA)1.

    Science.gov (United States)

    Cook, Suellen S; Whittock, Lucy; Wright, Simon W; Hallegraeff, Gustaaf M

    2011-06-01

    The widespread coccolithophorid Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler plays a pivotal role in the carbon pump and is known to exhibit significant morphological, genetic, and physiological diversity. In this study, we compared photosynthetic pigments and morphology of triplicate strains of Southern Ocean types A and B/C. The two morphotypes differed in width of coccolith distal shield elements (0.11-0.24 μm, type A; 0.06-0.12 μm, type B/C) and morphology of distal shield central area (grill of curved rods in type A; thin plain plate in type B/C) and showed differences in carotenoid composition. The mean 19'-hexanoyloxyfucoxanthin (Hex):chl a ratio in type B/C was >1, whereas the type A ratio was huxleyi var. aurorae var. nov. S. S. Cook et Hallegr. © 2011 Phycological Society of America.

  10. Leaf Morphology, Photosynthetic Performance, Chlorophyll Fluorescence, Stomatal Development of Lettuce (Lactuca sativa L.) Exposed to Different Ratios of Red Light to Blue Light.

    Science.gov (United States)

    Wang, Jun; Lu, Wei; Tong, Yuxin; Yang, Qichang

    2016-01-01

    Red and blue light are both vital factors for plant growth and development. We examined how different ratios of red light to blue light (R/B) provided by light-emitting diodes affected photosynthetic performance by investigating parameters related to photosynthesis, including leaf morphology, photosynthetic rate, chlorophyll fluorescence, stomatal development, light response curve, and nitrogen content. In this study, lettuce plants (Lactuca sativa L.) were exposed to 200 μmol⋅m(-2)⋅s(-1) irradiance for a 16 h⋅d(-1) photoperiod under the following six treatments: monochromatic red light (R), monochromatic blue light (B) and the mixture of R and B with different R/B ratios of 12, 8, 4, and 1. Leaf photosynthetic capacity (A max) and photosynthetic rate (P n) increased with decreasing R/B ratio until 1, associated with increased stomatal conductance, along with significant increase in stomatal density and slight decrease in stomatal size. P n and A max under B treatment had 7.6 and 11.8% reduction in comparison with those under R/B = 1 treatment, respectively. The effective quantum yield of PSII and the efficiency of excitation captured by open PSII center were also significantly lower under B treatment than those under the other treatments. However, shoot dry weight increased with increasing R/B ratio with the greatest value under R/B = 12 treatment. The increase of shoot dry weight was mainly caused by increasing leaf area and leaf number, but no significant difference was observed between R and R/B = 12 treatments. Based on the above results, we conclude that quantitative B could promote photosynthetic performance or growth by stimulating morphological and physiological responses, yet there was no positive correlation between P n and shoot dry weight accumulation.

  11. Comparison of Methods for Estimating Fractional Cover of Photosynthetic and Non-Photosynthetic Vegetation in the Otindag Sandy Land Using GF-1 Wide-Field View Data

    OpenAIRE

    Xiaosong Li; Guoxiong Zheng; Jinying Wang; Cuicui Ji; Bin Sun; Zhihai Gao

    2016-01-01

    Photosynthetic vegetation (PV) and non-photosynthetic vegetation (NPV) are important ground cover types for desertification monitoring and land management. Hyperspectral remote sensing has been proven effective for separating NPV from bare soil, but few studies determined fractional cover of PV (fpv) and NPV (fnpv) using multispectral information. The purpose of this study is to evaluate several spectral unmixing approaches for retrieval of fpv and fnpv in the Otindag Sandy Land using GF-1 wi...

  12. Okadaic acid inhibits cell growth and photosynthetic electron transport in the alga Dunaliella tertiolecta

    Energy Technology Data Exchange (ETDEWEB)

    Perreault, Francois; Matias, Marcelo Seleme; Oukarroum, Abdallah [Department of Chemistry, Universite du Quebec a Montreal, 2101, Rue Jeanne Mance, Montreal, QC, Canada H2X 2J6 (Canada); Matias, William Gerson [Department of Chemistry, Universite du Quebec a Montreal, 2101, Rue Jeanne Mance, Montreal, QC, Canada H2X 2J6 (Canada); Laboratorio de Toxicologia Ambiental, LABTOX, Depto. de Engenharia Sanitaria e Ambiental, Universidade Federal de Santa Catarina, Campus Universitario, CEP: 88040-970, Florianopolis, SC (Brazil); Popovic, Radovan, E-mail: popovic.radovan@uqam.ca [Department of Chemistry, Universite du Quebec a Montreal, 2101, Rue Jeanne Mance, Montreal, QC, Canada H2X 2J6 (Canada)

    2012-01-01

    Okadaic acid (OA), which is produced by several dinoflagellate species, is a phycotoxin known to induce a decrease of biomass production in phytoplankton. However, the mechanisms of OA cytotoxicity are still unknown in microalgae. In this study, we exposed the green microalga Dunaliella tertiolecta to OA concentrations of 0.05 to 0.5 {mu}M in order to evaluate its effects on cell division, reactive oxygen species production and photosynthetic electron transport. After 72 h of treatment under continuous illumination, OA concentrations higher than 0.10 {mu}M decreased culture cell density, induced oxidative stress and inhibited photosystem II electron transport capacity. OA effect in D. tertiolecta was strongly light dependent since no oxidative stress was observed when D. tertiolecta was exposed to OA in the dark. In the absence of light, the effect of OA on culture cell density and photosystem II activity was also significantly reduced. Therefore, light appears to have a significant role in the toxicity of OA in microalgae. Our results indicate that the site of OA interaction on photosynthetic electron transport is likely to be at the level of the plastoquinone pool, which can lead to photo-oxidative stress when light absorbed by the light-harvesting complex of photosystem II cannot be dissipated via photochemical pathways. These findings allowed for a better understanding of the mechanisms of OA toxicity in microalgae. - Highlights: Black-Right-Pointing-Pointer Exposition of Dunaliella tertiolecta to okadaic acid in light conditions results in reactive oxygen species formation. Black-Right-Pointing-Pointer Inhibition of photosystem II is dependent on oxidative stress and effects of okadaic acid on the plastoquinone pool. Black-Right-Pointing-Pointer Oxidative stress and inhibition of photosynthesis increase okadaic acid effect on cell density in light conditions. Black-Right-Pointing-Pointer Okadaic acid induces toxicity in algae via both light-dependent and light

  13. The magnitude of interannual variability of ecosystem photosynthetic capacity is controled by stand age and biodiversity

    Science.gov (United States)

    Musavi, Talie; Migliavacca, Mirco; Mahecha, Miguel D.; Reichstein, Markus; Kattge, Jens; Wirth, Christian; Black, T. Andrew; Janssens, Ivan; Knohl, Alexander; Loustau, Denis; Roupsard, Olivier; Varlagin, Andrej; Rambal, Serge; Cescatti, Alessandro; Gianelle, Damiano; Kondo, Hiroaki; Tamrakar, Rijan

    2017-04-01

    Gross primary productivity, GPP, the total uptake of carbon dioxide (CO2) by ecosystems via photosynthesis, is the largest flux in the global carbon cycle. The photosynthetic capacity at light saturation (GPPsat) is a fundamental ecosystem functional property and its interannual variability (IAV) is propagated to the net ecosystem exchange of CO2. In this contribution we made use of a variety of data streams consisting of ecosystem-atmosphere CO2 fluxes measured at eddy covariance flux sites with more than 4 years of data, the GPPsat derived at the different sites, information about climate (temperature, precipitation, and water availability index - WAI), biodiversity information and species richness, stand age, and plant traits, nutrient availability indexes derived from field campaigns, ancillary databases, and the literature. We also used data about forest structure derived from satellite products. Sites were selected according to the availability of eddy covariance flux measurements for at least 4 years, information about stand age, canopy cover, canopy height, and species abundance. The resulting global database consisted of 50 sites with different vegetation types across different climatic regions. Considering the importance of the understanding of IAV in CO2 fluxes to improve the predictive capacity of the global carbon cycle we analyzed a range of alternative hypotheses and potential drivers of the magnitude of IAV in GPPsat in forest ecosystems. The results show that the IAV in GPPsat within sites is driven by climate (i.e. fluctuations in air temperature and soil water availability), but the magnitude of IAV in GPPsat is related to ecosystem structure, and more in details to stand age and biodiversity (R2=0.55, p<0.0001). We conclude that irrespective of forest type the IAV of GPPsat in older and more diverse forests is dampened, and is higher in younger forests with few dominant species.

  14. Photosynthetic control of electron transport and the regulation of gene expression

    NARCIS (Netherlands)

    Foyer, C.H.; Neukermans, J.; Queval, G.; Noctor, G.; Harbinson, J.

    2012-01-01

    The term ‘photosynthetic control’ describes the short- and long-term mechanisms that regulate reactions in the photosynthetic electron transport (PET) chain so that the rate of production of ATP and NADPH is coordinated with the rate of their utilization in metabolism. At low irradiances these

  15. Influence of stomatic aperture on photosynthetic activity of bean-seedlings leaves

    International Nuclear Information System (INIS)

    Suarez Moya, J.; Fernandez Gonzalez, J.

    1984-01-01

    The present paper contains the data of photosynthetic activity and stomatic aperture of bean-seedlings Ieaves, and the relations obtained with both results. It has been observed that the product of photosynthetic activity by the resistance; to transpiration measured by a promoter ia a constant, between some limits. (Author) 45 refs

  16. Detection of photosynthetic performance of Stipa bungeana seedlings under climatic change using chlorophyll fluorescence imaging

    Directory of Open Access Journals (Sweden)

    Xiliang eSong

    2016-01-01

    Full Text Available In this study, the impact of future climate change on photosynthetic efficiency as well as energy partitioning in the Stipa bungeana was investigated by using chlorophyll fluorescence imaging (CFI technique. Two thermal regimes (room temperature, T0: 23.0/17.0℃; High temperature, T6: 29.0/23.0℃ and three water conditions (Control, W0; Water deficit, W-30; excess precipitation, W+30 were set up in artificial control chambers. The results showed that excess precipitation had no significant effect on chlorophyll fluorescence parameters, while water deficit decreased the maximal quantum yield of photosystem II (PSII photochemistry for the dark-adapted state (Fv/Fm by 16.7%, with no large change in maximal quantum yield of PSII photochemistry for the light-adapted state (FV'/FM' and coefficient of the photochemical quenching (qP at T0 condition. Under T6 condition, high temperature offset the negative effect of water deficit on Fv/Fm and enhanced the positive effect of excess precipitation on Fv/Fm, Fv'/Fm' and qP, the values of which all increased. This indicates that the temperature higher by 6 ℃ will be beneficial to the photosynthetic performance of S. bungeana. Spatial changes of photosynthetic performance were monitored in three areas of interest (AOIs located on the bottom, middle and upper position of leaf. Chlorophyll fluorescence images (Fv/Fm, actual quantum yield of PSII photochemistry for the light-adapted state (ΦPSII, quantum yield of nonregulated energy dissipation for the light-adapted state (ΦNO at T0 condition, and ΦPSII at T6 condition showed a large spatial variation, with greater value of ΦNO and lower values of Fv/Fm and ΦPSII in the upper position of leaves. Moreover, there was a closer relationship between ΦPSII and ΦNO, suggesting that the energy dissipation by non-regulated quenching mechanisms played a dominant role in the yield of PSII photochemistry. It was also found that, among all measured fluorescence

  17. Effect of gamma radiation on photosynthetic metabolism of Chlorella pyrenoidosa studied by 14{sup C}O{sub 2} assimilation; Estudio del efecto de la radiacion gamma sobre el metabolismo fotosintetico de Chlorella pyrenoidosa mediante asimilacion de 14{sup C}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Martin, C; Fernandez, J

    1983-07-01

    The effect of five dose of gamma radiation (10, 100, 500, 1000 and 5000 Gy) on photosynthetic activity and metabolism of the primary products of photosynthesis has been studied, on Chlorella pyrenoidoBa cultures, by 14{sup C}O{sub 2} assimilation. The photosynthetic assimilation rate is remarkably depressed after irradiation at 500, 1000 and 5000 Gy dose, which also produce a significant change in radioactivity distribution pattern of primary compounds from photosynthesis. No significant effects have been observed on photosynthetic metabolism after irradiation at 10 and 100 Gy. (Author) 19 refs.

  18. Interactions between heavy metals and photosynthetic materials studied by optical techniques.

    Science.gov (United States)

    Ventrella, Andrea; Catucci, Lucia; Piletska, Elena; Piletsky, Sergey; Agostiano, Angela

    2009-11-01

    In this work studies on rapid inhibitory interactions between heavy metals and photosynthetic materials at different organization levels were carried out by optical assay techniques, investigating the possibility of applications in the heavy metal detection field. Spinach chloroplasts, thylakoids and Photosystem II proteins were employed as biotools in combination with colorimetric assays based on dichlorophenol indophenole (DCIP) photoreduction and on fluorescence emission techniques. It was found that copper and mercury demonstrated a strong and rapid photosynthetic activity inhibition, that varied from proteins to membranes, while other metals like nickel, cobalt and manganese produced only slight inhibition effects on all tested photosynthetic materials. By emission measurements, only copper was found to rapidly influence the photosynthetic material signals. These findings give interesting information about the rapid effects of heavy metals on isolated photosynthetic samples, and are in addition to the literature data concerning the effects of growth in heavy metal enriched media.

  19. The Effect of Static Magnetic Forces on Water Contents and Photosynthetic Pigments in Sweet Basil Ocimum basilicum L. (Lamiaceae)

    Energy Technology Data Exchange (ETDEWEB)

    Taia, Wafaa K; Kotbi, Abeer M [Alexandria Univ., Faculty of Science, Botany Dept., Alexandria (Egypt); AlZahrani, Hassan S [Faculty of Science, King AbdulAziz Univ., Biology Dept., Jeddah (Saudi Arabia)

    2007-07-01

    Three different magnetic regimes; aerial, surface and buried; each with three different forces, have been used to investigate their effects on the water contents and photosynthetic pigments of sweet basil plants (Ocimum basilicum L.). Two groups of sweet basil seeds, Ocimum basilicum L. have been cultivated, one under normal conditions and the second has been subdivided into three portion (aerial, surface and buried) to examine the effect of different magnetic forces coming from the three directions on the resulted plants. At all directions of magnets, water contents have been significantly affected by the magnetic forces. Chlorophyll A and carotene contents have been affected, as well, according to the three magnetic forces coming from soil surface regime only. Chlorophyll B did not significantly affected by differences magnetic forces in the three regimes, but it is affected by magnetism wherever its direction or force. But all the photosynthetic pigments contents (Chlorophyll A, B and Carotenes) decreased significantly than the control in the three magnetic regimes., but without any effect according to differences in the magnetic force in the aerial and burried regimes of magnetism. It was concluded that magnetism affects both water absorption and retention , the most influenced regime was the aerial magnets followed by the surface and buried ones. This result can be interpreted by the ionization of water which makes water ions respond to magnetic forces. Photosynthetic pigments have been decreased significantly by the exposure to magnetic fields, irrespective to its direction or force and this may be due to the effect of magnetic fields on the reduction in plastids inside the cells. (author)

  20. The Effect of Static Magnetic Forces on Water Contents and Photosynthetic Pigments in Sweet Basil Ocimum basilicum L. (Lamiaceae)

    International Nuclear Information System (INIS)

    Taia, Wafaa K; Kotbi, Abeer M; AlZahrani, Hassan S

    2007-01-01

    Three different magnetic regimes; aerial, surface and buried; each with three different forces, have been used to investigate their effects on the water contents and photosynthetic pigments of sweet basil plants (Ocimum basilicum L.). Two groups of sweet basil seeds, Ocimum basilicum L. have been cultivated, one under normal conditions and the second has been subdivided into three portion (aerial, surface and buried) to examine the effect of different magnetic forces coming from the three directions on the resulted plants. At all directions of magnets, water contents have been significantly affected by the magnetic forces. Chlorophyll A and carotene contents have been affected, as well, according to the three magnetic forces coming from soil surface regime only. Chlorophyll B did not significantly affected by differences magnetic forces in the three regimes, but it is affected by magnetism wherever its direction or force. But all the photosynthetic pigments contents (Chlorophyll A, B and Carotenes) decreased significantly than the control in the three magnetic regimes., but without any effect according to differences in the magnetic force in the aerial and burried regimes of magnetism. It was concluded that magnetism affects both water absorption and retention , the most influenced regime was the aerial magnets followed by the surface and buried ones. This result can be interpreted by the ionization of water which makes water ions respond to magnetic forces. Photosynthetic pigments have been decreased significantly by the exposure to magnetic fields, irrespective to its direction or force and this may be due to the effect of magnetic fields on the reduction in plastids inside the cells. (author)

  1. Effects of CO2 on the tolerance of photosynthesis to heat stress can be affected by photosynthetic pathway and nitrogen.

    Science.gov (United States)

    Wang, Dan; Heckathorn, Scott A; Hamilton, E William; Frantz, Jonathan

    2014-01-01

    Determining effects of elevated CO2 and N on photosynthetic thermotolerance is critical for predicting plant responses to global warming. We grew Hordeum vulgare (barley, C3) and Zea mays (corn, C4) at current or elevated CO2 (370, 700 ppm) and limiting or optimal soil N (0.5, 7.5 mmol/L). We assessed thermotolerance of net photosynthesis (Pn), photosystem II efficiency in the light (Fv'/Fm'), photochemical quenching (qp), carboxylation efficiency (CE), and content of rubisco activase and major heat-shock proteins (HSPs). For barley, elevated CO2 had no effect on Pn, qp, and CE at both high and low N and only a positive effect on Fv'/Fm' at high N. However, for corn, Pn, Fv'/Fm', qp, and CE were decreased substantially by elevated CO2 under high and low N, with greater decreases at high N for all but qp. The negative effects of high CO2 during heat stress on photosynthesis were correlated with rubisco activase and HSPs content, which decreased with heat stress, especially for low-N corn. These results indicate that stimulatory effects of elevated CO2 at normal temperatures on photosynthesis and growth (only found for high-N barley) may be partly offset by neutral or negative effects during heat stress, especially for C4 species. Thus, CO2 and N effects on photosynthetic thermotolerance may contribute to changes in plant productivity, distribution, and diversity in future.

  2. Asymmetrical effects of mesophyll conductance on fundamental photosynthetic parameters and their relationships estimated from leaf gas exchange measurements.

    Science.gov (United States)

    Sun, Ying; Gu, Lianhong; Dickinson, Robert E; Pallardy, Stephen G; Baker, John; Cao, Yonghui; DaMatta, Fábio Murilo; Dong, Xuejun; Ellsworth, David; Van Goethem, Davina; Jensen, Anna M; Law, Beverly E; Loos, Rodolfo; Martins, Samuel C Vitor; Norby, Richard J; Warren, Jeffrey; Weston, David; Winter, Klaus

    2014-04-01

    Worldwide measurements of nearly 130 C3 species covering all major plant functional types are analysed in conjunction with model simulations to determine the effects of mesophyll conductance (g(m)) on photosynthetic parameters and their relationships estimated from A/Ci curves. We find that an assumption of infinite g(m) results in up to 75% underestimation for maximum carboxylation rate V(cmax), 60% for maximum electron transport rate J(max), and 40% for triose phosphate utilization rate T(u) . V(cmax) is most sensitive, J(max) is less sensitive, and T(u) has the least sensitivity to the variation of g(m). Because of this asymmetrical effect of g(m), the ratios of J(max) to V(cmax), T(u) to V(cmax) and T(u) to J(max) are all overestimated. An infinite g(m) assumption also limits the freedom of variation of estimated parameters and artificially constrains parameter relationships to stronger shapes. These findings suggest the importance of quantifying g(m) for understanding in situ photosynthetic machinery functioning. We show that a nonzero resistance to CO2 movement in chloroplasts has small effects on estimated parameters. A non-linear function with gm as input is developed to convert the parameters estimated under an assumption of infinite gm to proper values. This function will facilitate gm representation in global carbon cycle models. © 2013 John Wiley & Sons Ltd.

  3. Terra Moderate Resolution Imaging Spectroradiometer (MODIS) Photosynthetically Available Radiation (PAR) Global Binned Data, reprocesing v2018

    Data.gov (United States)

    National Aeronautics and Space Administration — MODIS (or Moderate Resolution Imaging Spectroradiometer) is a key instrument aboard the Terra (EOS AM) and Aqua (EOS PM) satellites. Terra's orbit around the Earth...

  4. Estimation of chromophoric dissolved organic matter (CDOM) and photosynthetic activity of estuarine phytoplankton using a multiple-fixed-wavelength spectral fluorometer.

    Science.gov (United States)

    Goldman, Emily A; Smith, Erik M; Richardson, Tammi L

    2013-03-15

    The utility of a multiple-fixed-wavelength spectral fluorometer, the Algae Online Analyser (AOA), as a means of quantifying chromophoric dissolved organic matter (CDOM) and phytoplankton photosynthetic activity was tested using algal cultures and natural communities from North Inlet estuary, South Carolina. Comparisons of AOA measurements of CDOM to those by spectrophotometry showed a significant linear relationship, but increasing amounts of background CDOM resulted in progressively higher over-estimates of chromophyte contributions to a simulated mixed algal community. Estimates of photosynthetic activity by the AOA at low irradiance (≈ 80 μmol quanta m(-2) s(-1)) agreed well with analogous values from the literature for the chlorophyte, Dunaliella tertiolecta, but were substantially lower than previous measurements of the maximum quantum efficiency of photosystem II (F(v)/F(m)) in Thalassiosira weissflogii (a diatom) and Rhodomonas salina (a cryptophyte). When cells were exposed to high irradiance (1500 μmol quanta m(-2) s(-1)), declines in photosynthetic activity with time measured by the AOA mirrored estimates of cellular fluorescence capacity using the herbicide 3'-(3, 4-dichlorophenyl)-1',1'-dimethyl urea (DCMU). The AOA shows promise as a tool for the continuous monitoring of phytoplankton community composition, CDOM, and the group-specific photosynthetic activity of aquatic ecosystems. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Global distribution of radiolytic H2 production in marine sediment and implications for subsurface life

    Science.gov (United States)

    Sauvage, J.; Flinders, A. F.; Spivack, A. J.; D'Hondt, S.

    2017-12-01

    We present the first global estimate of radiolytic H2production in marine sediment. Knowledge of microbial electron donor production rates is critical to understand the bioenergetics of Earth's subsurface ecosystems In marine sediment, radiolysis of water by radiation from naturally occurring radionuclides leads to production of reduced (H2) and oxidized (H2O2, O2) species. Water radiolysis is catalyzed by marine sediment. The magnitude of catalysis depends on sediment composition and radiation type. Deep-sea clay is especially effective at enhancing H2 yields, increasing yield by more than an order of magnitude relative to pure water. This previously unrecognized catalytic effect of geological materials on radiolytic H2 production is important for fueling microbial life in the subseafloor, especially in sediment with high catalytic power. Our estimate of radiolytic H2 production is based on spatially integrating a previously published model and uses (i) experimentally constrained radiolytic H2 yields for the principal marine sediment types, (ii) bulk sediment radioactive element content of sediment cores in three ocean basins (N. Atlantic, N. and S. Pacific), and global distributions of (iii) seafloor lithology, (iv) sediment porosity, and (v) sediment thickness. We calculate that global radiolytic H2 production in marine sediment is 1.6E+12 mol H2 yr-1. This production rate is small relative to the annual rate of photosynthetic organic-matter production in the surface ocean. The globally integrated ratio of radiolytic H2 production relative to photosynthetic primary production is 4.1E-4, based on electron equivalences. Although small relative to global photosynthetic biomass production, sediment-catalyzed production of radiolytic products is significant in the subseafloor. Our analysis of 9 sites in the N. Atlantic, N. and S. Pacific suggests that H2 is the primary microbial fuel in organic-poor sediment older than a few million years; at these sites, calculated

  6. A cost-effective microbial fuel cell to detect and select for photosynthetic electrogenic activity in algae and cyanobacteria

    NARCIS (Netherlands)

    Luimstra, V.M.; Kennedy, S.J.; Güttler, J.; Wood, S.A.; Williams, D.E.; Packer, M.A.

    2014-01-01

    This work describes the development of an easily constructed, cost-effective photosynthetic microbial fuel cell design with highly reproducible electrochemical characteristics that can be used to screen algae and cyanobacteria for photosynthetic electrogenic activity. It is especially suitable for

  7. Methane dynamics in Northern Wetlands: Significance of vascular plants

    Energy Technology Data Exchange (ETDEWEB)

    Joabsson, Anna

    2001-09-01

    The studies presented illustrate several different aspects of the impact of vascular plants on methane emissions from northern natural wetlands. The subject has been approached on different scales, ranging from the study of microbial substrates in the vicinity of a single plant root, to an attempt to extrapolate some of the results to the entire northern hemisphere north of 50 meridian. The main overall conclusions from the papers are that vascular plants affect net methane emissions 1) by offering an efficient route of transport to the atmosphere so that methane oxidation in oxic surface soils is avoided, and 2) by being sources of methanogenic substrate. The degree to which vascular wetland plants affect methane emissions seems to be dependent on species-specific differences in both the capacity to act as gas conduits and the exudation of labile carbon compounds to the soil. An intimate coupling between vascular plant production and methane emission was found in an Arctic tundra wetland, although other environmental variables (water table, temperature) also contributed significantly to the explained variation in methane exchange. Studies of vascular plant extidation of organic acids suggest that the available pool of methanogenic substrates is both qualitatively and quantitatively correlated to vascular plant production (photosynthetic rate). On global scales, vascular plant production as a single factor does not seem to be sufficient to explain the majority of variation in methane flux patterns. Based on comparable experiments at five different sites in the northwestern Eurasian and Greenlandic North, we suggest that mean seasonal soil temperature is the best predictor of methane exchange on broad spatial and temporal scales.

  8. Rescuing ethanol photosynthetic production of cyanobacteria in non-sterilized outdoor cultivations with a bicarbonate-based pH-rising strategy.

    Science.gov (United States)

    Zhu, Zhi; Luan, Guodong; Tan, Xiaoming; Zhang, Haocui; Lu, Xuefeng

    2017-01-01

    Ethanol photosynthetic production based on cyanobacteria cell factories utilizing CO 2 and solar energy provides an attractive solution for sustainable production of green fuels. However, the scaling up processes of cyanobacteria cell factories were usually threatened or even devastated by biocontaminations, which restricted biomass or products accumulations of cyanobacteria cells. Thus it is of great significance to develop reliable biocontamination-controlling strategies for promoting ethanol photosynthetic production in large scales. The scaling up process of a previously developed Synechocystis strain Syn-HZ24 for ethanol synthesis was severely inhibited and devastated by a specific contaminant, Pannonibacter phragmitetus , which overcame the growths of cyanobacteria cells and completely consumed the ethanol accumulation in the cultivation systems. Physiological analysis revealed that growths and ethanol-consuming activities of the contaminant were sensitive to alkaline conditions, while ethanol-synthesizing cyanobacteria strain Syn-HZ24 could tolerate alkaline pH conditions as high as 11.0, indicating that pH-increasing strategy might be a feasible approach for rescuing ethanol photosynthetic production in outdoor cultivation systems. Thus, we designed and evaluated a Bicarbonate-based Integrated Carbon Capture System (BICCS) derived pH-rising strategy to rescue the ethanol photosynthetic production in non-sterilized conditions. In lab scale artificially simulated systems, pH values of BG11 culture medium were maintained around 11.0 by 180 mM NaHCO 3 and air steam, under which the infection of Pannonibacter phragmitetus was significantly restricted, recovering ethanol production of Syn-HZ24 by about 80%. As for outdoor cultivations, ethanol photosynthetic production of Syn-HZ24 was also successfully rescued by the BICCS-derived pH-rising strategy, obtaining a final ethanol concentration of 0.9 g/L after 10 days cultivation. In this work, a novel product

  9. Seasonal photosynthetic activity in evergreen conifer leaves monitored with spectral reflectance

    Science.gov (United States)

    Wong, C. Y.; Gamon, J. A.

    2013-12-01

    Boreal evergreen conifers must maintain photosynthetic systems in environments where temperatures vary greatly across seasons from high temperatures in the summer to freezing levels in the winter. This involves seasonal downregulation and photoprotection during periods of extreme temperatures. To better understand this downregulation, seasonal dynamics of photosynthesis of lodgepole (Pinus contorta D.) and ponderosa pine (Pinus ponderosa D.) were monitored in Edmonton, Canada over two years. Spectral reflectance at the leaf and stand scales was measured weekly and the Photochemical Reflectance Index (PRI), often used as a proxy for chlorophyll and carotenoid pigment levels and photosynthetic light-use efficiency (LUE), was used to track the seasonal dynamics of photosynthetic activity. Additional physiological measurements included leaf pigment content, chlorophyll fluorescence, and gas exchange. All the metrics indicate large seasonal changes in photosynthetic activity, with a sharp transition from winter downregulation to active photosynthesis in the spring and a more gradual fall transition into winter. The PRI was a good indicator of several other variables including seasonally changing photosynthetic activity, chlorophyll fluorescence, photosynthetic LUE, and pigment pool sizes. Over the two-year cycle, PRI was primarily driven by changes in constitutive (chlorophyll:carotenoid) pigment levels correlated with seasonal photosynthetic activity, with a much smaller variation caused by diurnal changes in xanthophyll cycle activity (conversion between violaxanthin & zeaxanthin). Leaf and canopy scale PRI measurements exhibited parallel responses during the winter-spring transition. Together, our findings indicate that evergreen conifers photosynthetic system possesses a remarkable degree of resilience in response to large temperature changes across seasons, and that optical remote sensing can be used to observe the seasonal effects on photosynthesis and

  10. Global biogeography of Prochlorococcus genome diversity in the surface ocean.

    Science.gov (United States)

    Kent, Alyssa G; Dupont, Chris L; Yooseph, Shibu; Martiny, Adam C

    2016-08-01

    Prochlorococcus, the smallest known photosynthetic bacterium, is abundant in the ocean's surface layer despite large variation in environmental conditions. There are several genetically divergent lineages within Prochlorococcus and superimposed on this phylogenetic diversity is extensive gene gain and loss. The environmental role in shaping the global ocean distribution of genome diversity in Prochlorococcus is largely unknown, particularly in a framework that considers the vertical and lateral mechanisms of evolution. Here we show that Prochlorococcus field populations from a global circumnavigation harbor extensive genome diversity across the surface ocean, but this diversity is not randomly distributed. We observed a significant correspondence between phylogenetic and gene content diversity, including regional differences in both phylogenetic composition and gene content that were related to environmental factors. Several gene families were strongly associated with specific regions and environmental factors, including the identification of a set of genes related to lower nutrient and temperature regions. Metagenomic assemblies of natural Prochlorococcus genomes reinforced this association by providing linkage of genes across genomic backbones. Overall, our results show that the phylogeography in Prochlorococcus taxonomy is echoed in its genome content. Thus environmental variation shapes the functional capabilities and associated ecosystem role of the globally abundant Prochlorococcus.

  11. Photosynthetic antennae systems: energy transport and optical absorption

    International Nuclear Information System (INIS)

    Reineker, P.; Supritz, Ch.; Warns, Ch.; Barvik, I.

    2004-01-01

    The energy transport and the optical line shape of molecular aggregates, modeling bacteria photosynthetic light-harvesting systems (chlorosomes in the case of Chlorobium tepidum or Chloroflexus aurantiacus and LH2 in the case of Rhodopseudomonas acidophila) is investigated theoretically. The molecular units are described by two-level systems with an average excitation energy ε and interacting with each other through nearest-neighbor interactions. For LH2 an elliptical deformation of the ring is also allowed. Furthermore, dynamic and in the case of LH2 also quasi-static fluctuations of the local excitation energies are taken into account, simulating fast molecular vibrations and slow motions of the protein backbone, respectively. The fluctuations are described by Gaussian Markov processes in the case of the chlorosomes and by colored dichotomic Markov processes, with exponentially decaying correlation functions, with small (λ s ) and large (λ) decay constants, in the case of LH2

  12. Mathematical Modeling of Acclimation Processes of the Photosynthetic Chain

    Directory of Open Access Journals (Sweden)

    S Heidari

    2016-10-01

    Full Text Available Introduction Photosynthetic energy conversion efficiency is characteristic of a system which is determined by interactions between various components of the system. The complex process of photosynthesis has been studied as a whole system which enables in silico examination of a large number of candidate genes for genetic engineering for a higher photosynthetic energy conversion efficiency. One of the most important environmental factors which influence the photosynthesis efficiency is light regime which can cause producing ROS components. To acclimate to such fluctuations, plants have evolved adaptive mechanisms to minimize damage of the photosynthetic apparatus excess light. A fast compatibility response to high light stresses is non-photochemical quenching process (NPQ, dissipating excessive energy to heat. Light harvested state switches into a quenched state by a conformational change of light harvesting complex (LHCII that regulated by xanthophylls and the PsbS protein within seconds. Low lumen pH activates xanthophyll synthesis via a xanthophyll cycle which consists of the de-epoxidation of violaxanthin to zeaxanthin by violaxanthin de-epoxidase in high light and inversely by zeaxanthin epoxidase in low light which occurs more slowly. Materials and Methods Thale cress (Arabidopsis thaliana (Chlombia-0 were grown on soil at 25/22 °C day/night temperature, with a 16/8 h photoperiod, and 40-70% (depend of plant species relative humidity. The light intensity was 150–200 µE m-2s-1 white light. Intensity of chlorophyll fluorescence was measured with PAM-2000 fluorometer (Heinz Walz, Germany and the manufacturer’s software (PamWin v.2. Results and Discussion In the present study, a dynamic kinetics amplified mathematical model was developed based on differential equations in order to predict short-term changes in NPQ in the process of adaptation to different light conditions. We investigated the stationary and dynamic behavior of the model

  13. Single Molecule Spectroscopy on Photosynthetic Pigment-Protein Complexes

    CERN Document Server

    Jelezko, F; Schuler, S; Thews, E; Tietz, C; Wechsler, A; Wrachtrup, J

    2001-01-01

    Single molecule spectroscopy was applied to unravel the energy transfer pathway in photosynthetic pigment-protein complexes. Detailed analysis of excitation and fluorescence emission spectra has been made for peripheral plant antenna LHC II and Photosystem I from cyanobacterium Synechococcus elongatus. Optical transitions of individual pigments were resolved under nonselective excitation of antenna chlorophylls. High-resolution fluorescence spectroscopy of individual plant antenna LHC II indicates that at low temperatures, the excitation energy is localized on the red-most Chl a pool absorbing at 680 nm. More than one pigment molecule is responsible for the fluorescence emission of the LHC II trimer. The spectral lines of single Chl a molecules absorbing at 675 nm are broadened because of the Foerster energy transfer towards the red-most pigments. Low-temperature spectroscopy on single PS I trimers indicates that two subgroups of pigments, which are present in the red antenna pool, differ by the strength of t...

  14. C4 photosynthetic machinery: insights from maize chloroplast proteomics

    Directory of Open Access Journals (Sweden)

    Qi eZhao

    2013-04-01

    Full Text Available C4 plants exhibit much higher CO2 assimilation rates than C3 plants. The specialized differentiation of mesophyll cell (M and bundle sheath cell (BS type chloroplasts is unique to C4 plants and improves photosynthesis efficiency. Maize (Zea mays is an important crop and model with C4 photosynthetic machinery. Current high-throughput quantitative proteomics approaches (e.g., 2DE, iTRAQ, and shotgun proteomics have been employed to investigate maize chloroplast structure and function. These proteomic studies have provided valuable information on C4 chloroplast protein components, photosynthesis, and other metabolic mechanisms underlying chloroplast biogenesis, stromal and membrane differentiation, as well as response to salinity, high/low temperature, and light stress. This review presents an overview of proteomics advances in maize chloroplast biology.

  15. Electrolyte control of photosynthetic electron transport in cyanobacteria

    International Nuclear Information System (INIS)

    Papageorgiou, G.C.

    1986-01-01

    Ion-permeable cells (permeaplasts) of the cyanobacterium Anacystis nidulans were prepared enzymatically and were characterized with respect to several structural and functional indices. The permeaplasts contain intact, ion-impermeable thylakoids and are photosynthetically active. The authors discuss how, employing these cells, they investigated the effects of cations, acting either on the outer, or on the inner thylakoid membrane surface, on photoinduced electron exchanges with anionic donors (Cyt c-550, plastocyanin, innersurface), or anionic acceptors (FeCN 3- ; outer surface). Cations accelerate such exchanges by accumulating near the solution-membrane interfaces and screening the negative surface charge of membranes. Electrostatic screening, however, is not the only contributing factor, and other electrolyte-linked influences must be invoked in order to interpret the experimental observations

  16. Photosynthetic production of diterpenoids in chloroplasts and cyanobacteria

    DEFF Research Database (Denmark)

    Vavitsas, Konstantinos

    Terpenoids are one of the largest classes of chemical compounds, some of them with industrial interest as nutraceuticals, biofuels, or chemical feedstocks. Diterpenoids are a large terpenoid subclass, and their chemical structure consists of a core skeleton of 20 carbon atoms. This skeleton can...... be further modified by cyclizing enzymes, and be decorated by the addition of chemical groups. Even though they are mainly plant-derived compounds, diterpenoid production in photosynthetic organisms is rather unexplored, with a few successful studies reported in the literature. In this thesis, I elaborate...... on the potential of using plant chloroplasts and cyanobacteria as biosynthetic vessels, with a focus on diterpenoid production, and on the potential direct linking of photosynthesis to drive electron-consuming enzymes, such as the monooxygenases cytochrome P450s. I subsequently present the full localization...

  17. Removal of triazine herbicides from freshwater systems using photosynthetic microorganisms

    International Nuclear Information System (INIS)

    Gonzalez-Barreiro, O.; Rioboo, C.; Herrero, C.; Cid, A.

    2006-01-01

    The uptake of the triazine herbicides, atrazine and terbutryn, was determined for two freshwater photosynthetic microorganisms, the green microalga Chlorella vulgaris and the cyanobacterium Synechococcus elongatus. An extremely rapid uptake of both pesticides was recorded, although uptake rate was lower for the cyanobacterium, mainly for atrazine. Other parameters related to the herbicide bioconcentration capacity of these microorganisms were also studied. Growth rate, biomass, and cell viability in cultures containing herbicide were clearly affected by herbicide uptake. Herbicide toxicity and microalgae sensitivity were used to determine the effectiveness of the bioconcentration process and the stability of herbicide removal. C. vulgaris showed higher bioconcentration capability for these two triazine herbicides than S. elongatus, especially with regard to terbutryn. This study supports the usefulness of such microorganisms, as a bioremediation technique in freshwater systems polluted with triazine herbicides

  18. Removal of triazine herbicides from freshwater systems using photosynthetic microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Barreiro, O. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain); Rioboo, C. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain); Herrero, C. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain); Cid, A. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain)]. E-mail: cid@udc.es

    2006-11-15

    The uptake of the triazine herbicides, atrazine and terbutryn, was determined for two freshwater photosynthetic microorganisms, the green microalga Chlorella vulgaris and the cyanobacterium Synechococcus elongatus. An extremely rapid uptake of both pesticides was recorded, although uptake rate was lower for the cyanobacterium, mainly for atrazine. Other parameters related to the herbicide bioconcentration capacity of these microorganisms were also studied. Growth rate, biomass, and cell viability in cultures containing herbicide were clearly affected by herbicide uptake. Herbicide toxicity and microalgae sensitivity were used to determine the effectiveness of the bioconcentration process and the stability of herbicide removal. C. vulgaris showed higher bioconcentration capability for these two triazine herbicides than S. elongatus, especially with regard to terbutryn. This study supports the usefulness of such microorganisms, as a bioremediation technique in freshwater systems polluted with triazine herbicides.

  19. Synthetic Biology with Cytochromes P450 Using Photosynthetic Chassis

    DEFF Research Database (Denmark)

    Gnanasekaran, Thiyagarajan

    , this modern field of synthetic biology is completely dependent on the nature of the chassis - the host organisms - for its endeavor. Of all the chassis, photosynthetic organisms such as cyanobacteria and plants gains special attention due to the remarkable amount of sunlight that is striking the Earth...... in cyanobacteria and plant chloroplasts for the purpose of light driven synthesis of bioactive compounds by using synthetic biology approaches. As model pathways, in this thesis, the pathway involved in the synthesis of the cyanogenic glucoside dhurrin from Sorghum bicolor, and the pathway involved......Synthetic biology is a rapidly growing engineering discipline in biology. It aims at building novel biological systems that do not exist in nature by selecting the interchangeable standardized biological parts that are already available in the nature, and assembling them in a specific order. Today...

  20. Characterization of the photosynthetic induction response in a Populus species with stomata barely responding to light changes.

    Science.gov (United States)

    Tang, Y; Liang, N

    2000-08-01

    The photosynthetic induction response is constrained by stomatal and biochemical limitations. However, leaves in some plants like Populus koreana x trichocarpa cv. Peace (a hybrid clone) may have little stomatal limitation because their stomata barely respond to changes in photon flux density (PFD). We examined the induction responses of leaves of well-watered and dehydrated P. koreana x trichocarpa plants grown in a high-light or a low-light regime. With an increase in PFD from 50 to 500 micromol m(-2) s(-1), steady-state stomatal conductance (g(s)) increased by only 0.25-8.2%, regardless of the initial g(s), but steady-state assimilation rate (A) increased by 550-1810%. Photosynthetic induction times required to reach 50% (IT50) and 90% (IT90) of A at high PFD were 60-90 s and 210-360 s, respectively. Examination of the dynamic relationships between A and g(s), and between A and intercellular CO2 concentration, indicated that the induction limitation was imposed completely by the biochemical components within 30-40 s after the PFD increase. Values of IT50 and IT90 were significantly higher in low-light leaves than in high-light leaves, whereas the induction state at 60 s and the induction efficiency at 60 and 120 s after the increase in PFD were lower in low-light leaves than in high-light leaves. Dehydration reduced leaf water potential (psi) significantly, resulting in a significantly decreased initial g(s). Leaf water potential had no significant effects on induction time in high-light leaves, but a low psi significantly reduced the induction time in low-light leaves. We conclude that the photosynthetic induction response was limited almost completely by biochemical components because the stomata barely responded to light changes. The biochemical limitation appeared to be higher in low-light leaves than in high-light leaves. Mild water stress may have reduced steady-state A and g(s), but it had little effect on the photosynthetic induction response in high

  1. Exclusion of solar UV radiation improves photosynthetic performance and yield of wheat varieties.

    Science.gov (United States)

    Kataria, Sunita; Guruprasad, K N

    2015-12-01

    Field studies were conducted to determine the potential for alterations in photosynthetic performance and grain yield of four wheat (Triticum aestivum) varieties of India- Vidisha, Purna, Swarna and Naveen Chandausi by ambient ultraviolet radiation (UV). The plants were grown in specially designed UV exclusion chambers, wrapped with filters that excluded UV-B (solar UV exclusion increased the leaf mass per area ratio, leaf weight ratio and chlorophylls per unit area of flag leaves in all the four varieties of wheat. Polyphasic chlorophyll a fluorescence transients from the flag leaves of UV excluded wheat plants gave a higher fluorescence yield. Exclusion of solar UV significantly enhanced photosynthetic performance as a consequence of increased efficiency of PS II, performance index (PIABS) and rate of photosynthesis in the flag leaves of wheat varieties along with a remarkable increase in carbonic anhydrase, Rubisco and nitrate reductase activities. This additional fixation of carbon and nitrogen by exclusion of UV was channelized towards the improvement in grain yield of wheat varieties as there was a decrease in the UV-B absorbing substances and an increase in soluble protein content in flag leaves of all the four varieties of wheat. The magnitude of response for UV exclusion for all the measured parameters was higher in two varieties of wheat Vidisha and Purna as compared to Swarna and Naveen Chandausi. Cumulative stress response index (CSRI) for each variety was developed from the cumulative sum of physiological and yield parameters such as leaf mass area ratio of flag leaf, total chlorophyll content, performance index at absorption basis, rate of photosynthesis and grain yield. All the varieties had a negative CSRI, demonstrating a negative impact of ambient UV radiation. Naveen Chandausi and Swarna are less sensitive to ambient UV radiation; Vidisha is more sensitive to both UV-A and UV-B and Purna is more sensitive to ambient UV-B radiation. Copyright

  2. Exploring the Limits to Photosynthetic Life in the Hyperarid Atacama (Chile) and Taklimakan (China) Deserts

    Science.gov (United States)

    Warren-Rhodes, K.; Ewing, S.; McKay, C. P.; Rhodes, K. L.

    2003-12-01

    Photosynthetic microbes inhabiting the cracks or fissures (chasmoendoliths) and undersides (hypoliths) of translucent stones function as the sole primary producers in the world's driest deserts. This poster reports on our studies of the distribution and survival of these microorganisms in the hyperarid core of the Atacama Desert--an extreme environment previously considered too dry to support photosynthetic life--and the Taklimakan Desert in China--one of the oldest and driest deserts on the Earth. In both deserts, we measured colonization rates and microclimate variables across natural precipitation gradients in order to investigate the role of moisture in the ecology and survival of hypolithic and chasmoendolithic microorganisms. Our results show 1000-fold variations in colonization rates--from 12% in the wettest portions of the Taklimakan Desert to 3000 y. At slightly wetter sites in the Atacama, Δ 14C of hypolith soils was progressively more enriched in proportion to increased MAP, with corresponding turnover times of >600 y (Δ 14C = -73 ‰ at sites with ˜5-10 mm MAP and ˜1 y Δ 14C = +12 ‰ ) as annual rainfall increased to ˜25 mm. At all sites, Δ 14C signatures of non-hypolith soils corresponded to turnover times that were longer by an order of magnitude, indicating significantly slower OC cycling by non-hypoliths. In the hyperarid core of the Atacama Desert, the prolonged lack of rainfall (decadal scales of a few millimeters) is responsible for possibly the lowest hypolithic and chasmoendolithic colonization rates observed in deserts on the Earth. Microclimate data for rock and soil surface moisture from rainfall, dew and frost suggest the particular form of moisture and its frequency may also explain observed differences in hypolithic versus chasmoendolithic colonization modes. These results hold theoretical and practical considerations for both terrestrial ecology and as analogs for possible life on Mars.

  3. Experimental climate warming decreases photosynthetic efficiency of lichens in an arid South African ecosystem.

    Science.gov (United States)

    Maphangwa, Khumbudzo Walter; Musil, Charles F; Raitt, Lincoln; Zedda, Luciana

    2012-05-01

    Elevated temperatures and diminished precipitation amounts accompanying climate warming in arid ecosystems are expected to have adverse effects on the photosynthesis of lichen species sensitive to elevated temperature and/or water limitation. This premise was tested by artificially elevating temperatures (increase 2.1-3.8°C) and reducing the amounts of fog and dew precipitation (decrease 30.1-31.9%), in an approximation of future climate warming scenarios, using transparent hexagonal open-top warming chambers placed around natural populations of four lichen species (Xanthoparmelia austroafricana, X. hyporhytida , Xanthoparmelia. sp., Xanthomaculina hottentotta) at a dry inland site and two lichen species (Teloschistes capensis and Ramalina sp.) at a humid coastal site in the arid South African Succulent Karoo Biome. Effective photosynthetic quantum yields ([Formula: see text]) were measured hourly throughout the day at monthly intervals in pre-hydrated lichens present in the open-top warming chambers and in controls which comprised demarcated plots of equivalent open-top warming chamber dimensions constructed from 5-cm-diameter mesh steel fencing. The cumulative effects of the elevated temperatures and diminished precipitation amounts in the open-top warming chambers resulted in significant decreases in lichen [Formula: see text]. The decreases were more pronounced in lichens from the dry inland site (decline 34.1-46.1%) than in those from the humid coastal site (decline 11.3-13.7%), most frequent and prominent in lichens at both sites during the dry summer season, and generally of greatest magnitude at or after the solar noon in all seasons. Based on these results, we conclude that climate warming interacting with reduced precipitation will negatively affect carbon balances in endemic lichens by increasing desiccation damage and reducing photosynthetic activity time, leading to increased incidences of mortality.

  4. Fagaceae tree species allocate higher fraction of nitrogen to photosynthetic apparatus than Leguminosae in Jianfengling tropical montane rain forest, China.

    Science.gov (United States)

    Tang, Jingchao; Cheng, Ruimei; Shi, Zuomin; Xu, Gexi; Liu, Shirong; Centritto, Mauro

    2018-01-01

    Variation in photosynthetic-nitrogen use efficiency (PNUE) is generally affected by several factors such as leaf nitrogen allocation and leaf diffusional conductances to CO2, although it is still unclear which factors significantly affect PNUE in tropical montane rain forest trees. In this study, comparison of PNUE, photosynthetic capacity, leaf nitrogen allocation, and diffusional conductances to CO2 between five Fagaceae tree species and five Leguminosae tree species were analyzed in Jianfengling tropical montane rain forest, Hainan Island, China. The result showed that PNUE of Fagaceae was significantly higher than that of Leguminosae (+35.5%), attributed to lower leaf nitrogen content per area (Narea, -29.4%). The difference in nitrogen allocation was the main biochemical factor that influenced interspecific variation in PNUE of these tree species. Fagaceae species allocated a higher fraction of leaf nitrogen to the photosynthetic apparatus (PP, +43.8%), especially to Rubisco (PR, +50.0%) and bioenergetics (PB +33.3%) in comparison with Leguminosae species. Leaf mass per area (LMA) of Leguminosae species was lower than that of Fagaceae species (-15.4%). While there was no significant difference shown for mesophyll conductance (gm), Fagaceae tree species may have greater chloroplast to total leaf surface area ratios and that offset the action of thicker cell walls on gm. Furthermore, weak negative relationship between nitrogen allocation in cell walls and in Rubisco was found for Castanopsis hystrix, Cyclobalanopsis phanera and Cy. patelliformis, which might imply that nitrogen in the leaves was insufficient for both Rubisco and cell walls. In summary, our study concluded that higher PNUE might contribute to the dominance of most Fagaceae tree species in Jianfengling tropical montane rain forest.

  5. Fagaceae tree species allocate higher fraction of nitrogen to photosynthetic apparatus than Leguminosae in Jianfengling tropical montane rain forest, China

    Science.gov (United States)

    Cheng, Ruimei; Shi, Zuomin; Xu, Gexi; Liu, Shirong; Centritto, Mauro

    2018-01-01

    Variation in photosynthetic-nitrogen use efficiency (PNUE) is generally affected by several factors such as leaf nitrogen allocation and leaf diffusional conductances to CO2, although it is still unclear which factors significantly affect PNUE in tropical montane rain forest trees. In this study, comparison of PNUE, photosynthetic capacity, leaf nitrogen allocation, and diffusional conductances to CO2 between five Fagaceae tree species and five Leguminosae tree species were analyzed in Jianfengling tropical montane rain forest, Hainan Island, China. The result showed that PNUE of Fagaceae was significantly higher than that of Leguminosae (+35.5%), attributed to lower leaf nitrogen content per area (Narea, –29.4%). The difference in nitrogen allocation was the main biochemical factor that influenced interspecific variation in PNUE of these tree species. Fagaceae species allocated a higher fraction of leaf nitrogen to the photosynthetic apparatus (PP, +43.8%), especially to Rubisco (PR, +50.0%) and bioenergetics (PB +33.3%) in comparison with Leguminosae species. Leaf mass per area (LMA) of Leguminosae species was lower than that of Fagaceae species (-15.4%). While there was no significant difference shown for mesophyll conductance (gm), Fagaceae tree species may have greater chloroplast to total leaf surface area ratios and that offset the action of thicker cell walls on gm. Furthermore, weak negative relationship between nitrogen allocation in cell walls and in Rubisco was found for Castanopsis hystrix, Cyclobalanopsis phanera and Cy. patelliformis, which might imply that nitrogen in the leaves was insufficient for both Rubisco and cell walls. In summary, our study concluded that higher PNUE might contribute to the dominance of most Fagaceae tree species in Jianfengling tropical montane rain forest. PMID:29390007

  6. Estimating hourly variation in photosynthetically active radiation across the UK using MSG SEVIRI data

    International Nuclear Information System (INIS)

    Pankaew, P; Milton, E J; Dash, J

    2014-01-01

    The amount of photosynthetically active radiation (PAR) reaching the Earth's surface is a key input variable in most gross primary productivity models. However, poor representation of PAR due to large pixel size or limited temporal sampling is one of the main sources of uncertainty in such models. This paper presents a method to estimate PAR at up to 1 km spatial resolution at a regional to global scale. The method uses broadband radiance data (400–1100nm) and per-pixel estimates of relative cloud cover from a geostationary satellite to estimate the amount of PAR reaching the Earth's surface at high spatial and temporal resolution (1–2 km and hourly). The method was validated using data from 54 pyranometers located at sites across the UK. Hourly averaged PAR over the range 400–1400 μmol m −2 s −1 was estimated with a mean bias error = 5.01 μmol m −2 s −1 (R 2 = 0.87), providing a source of accurate data for high resolution models of gross primary productivity

  7. Photosynthetic behavior, growth and essential oil production of Melissa officinalis L. cultivated under colored shade nets

    Directory of Open Access Journals (Sweden)

    Graziele C Oliveira

    2016-03-01

    Full Text Available The modulation of light is of importance during cultivation of medicinal plants to obtain desirable morphological and physiological changes associated with the maximum production of active principles. This study aimed to evaluate the effect of the light spectrum transmitted by colored shade nets on growth, essential oil production and photosynthetic behavior in plants of lemon balm (Melissa officinalis L. Plants were cultivated in pots for 4-mo under black, red, and blue nets with 50% shading, and full sunlight exposure. Biometric and anatomical variables, essential oil yield, global solar radiation, photon flux density, chlorophyll content, and gas exchange parameters were measured in M. officinalis leaves. The results showed that despite being considered a partial shade plant, this species is able to adapt to full sunlight conditions without increasing biomass production. The spectral changes provided by colored shade nets did not caused any noticeable change in leaf anatomy of M. officinalis. However, the use of blue net resulted in increments of 116% in plant height, 168% in leaf area, 42% in chlorophyll content and 30% in yield of essential oil in lemon balm plants. These plant's qualities make the use of blue net a cultivation practice suitable for commercial use.

  8. Relationship between photosynthetic pigments and chlorophyll fluorescence in soybean under varying phosphorus nutrition at ambient and elevated CO2

    Science.gov (United States)

    Photosynthetic pigments such as chlorophyll (Chl) a, Chl b and carotenoids concentration, and chlorophyll fluorescence (CF) have widely been used as indicators of stress and photosynthetic performance in plants. Although photosynthetic pigments and CF are partly interdependent due to absorption and ...

  9. Identification and growth conditions of purple non-sulfur photosynthetic bacteria isolated from palm oil mill effluent

    International Nuclear Information System (INIS)

    Radziah Ariffin

    2004-01-01

    An indigenous strain of the purple non-sulphur photosynthetic bacterium, isolated from palm oil mill effluent was presumably identified as species of Rhodopseudomonas palustris. Cultivation in synthetic medium under different conditions indicated that it gave maximum carotenoid and bacteriophyll synthesis under anaerobic conditions in the light with values of 12.6 and 108.1 mg/g dry cell weight respectively. These values were significantly higher than the pigment content obtained from aerobic cultivation. The specific growth rates in anaerobic was twice those in aerobic conditions in the light. Growth was not occurred in anaerobic or aerobic conditions in the dark. (Author)

  10. A photosynthetic-plasmonic-voltaic cell: Excitation of photosynthetic bacteria and current collection through a plasmonic substrate

    International Nuclear Information System (INIS)

    Samsonoff, Nathan; Ooms, Matthew D.; Sinton, David

    2014-01-01

    Excitation of photosynthetic biofilms using surface-confined evanescent light fields enables energy dense photobioreactors, while electrode-adhered biofilms can provide electricity directly. Here, we demonstrate concurrent light delivery and electron transport through a plasmonically excited metal film. Biofilms of cyanobacterium Synechococcus bacillaris on 50-nm gold films are excited via the Kretschmann configuration at λ = 670 nm. Cells show light/dark response to plasmonic excitation and grow denser biofilms, closer to the electrode surface, as compared to the direct irradiated case. Directly irradiated biofilms produced average electrical powers of 5.7 μW/m 2 and plasmonically excited biofilms produced average electrical powers of 5.8 μW/m 2 , with individual biofilms producing as much as 12 μW/m 2

  11. A photosynthetic-plasmonic-voltaic cell: Excitation of photosynthetic bacteria and current collection through a plasmonic substrate

    Energy Technology Data Exchange (ETDEWEB)

    Samsonoff, Nathan; Ooms, Matthew D.; Sinton, David [Department of Mechanical and Industrial Engineering, and Institute for Sustainable Energy, University of Toronto, Toronto M5S 3G8 (Canada)

    2014-01-27

    Excitation of photosynthetic biofilms using surface-confined evanescent light fields enables energy dense photobioreactors, while electrode-adhered biofilms can provide electricity directly. Here, we demonstrate concurrent light delivery and electron transport through a plasmonically excited metal film. Biofilms of cyanobacterium Synechococcus bacillaris on 50-nm gold films are excited via the Kretschmann configuration at λ = 670 nm. Cells show light/dark response to plasmonic excitation and grow denser biofilms, closer to the electrode surface, as compared to the direct irradiated case. Directly irradiated biofilms produced average electrical powers of 5.7 μW/m{sup 2} and plasmonically excited biofilms produced average electrical powers of 5.8 μW/m{sup 2}, with individual biofilms producing as much as 12 μW/m{sup 2}.

  12. Continuous high and low temperature induced a decrease of photosynthetic activity and changes in the diurnal fluctuations of organic acids in Opuntia streptacantha.

    Directory of Open Access Journals (Sweden)

    Zaida Zarely Ojeda-Pérez

    Full Text Available Opuntia plants grow naturally in areas where temperatures are extreme and highly variable in the day during the entire year. These plants survive through different adaptations to respond to adverse environmental conditions. Despite this capability, it is unknown how CAM photosynthetic activity and growth in Opuntia plantlets is affected by constant heat or cold. Therefore, the main objective of this research was to evaluate the short-term effect of high (40°C and low (4°C continuous temperatures on the photosynthetic efficiency, the organic acid content (malic acid and the relative growth rate (RGR in seven-month-old Opuntia streptacantha plantlets during 5, 10, and 15 days. Chlorophyll fluorescence analysis allowed us to determine that high temperatures negatively impact the photosynthetic efficiency of O. streptacantha plantlets, which exhibited the lowest values of maximum quantum efficiency of the photosystem II (Fv/Fm = 52%, Fv/F0 = 85%, operational quantum yield of PS (ΦPSII = 65% and relative electron transport rate (rETR = 65%, as well as highest values of basal fluorescence (F0 = 226% during 15 days of treatment. Similarly, low temperatures decreased Fv/Fm (16%, Fv/F0 (50%, ΦPSII and rETR (16%. High temperatures also decreased nocturnal acidification in approximately 34-50%, whereas low temperatures increased it by 30-36%. Additionally, both continuous temperatures affected drastically diurnal consumption of malic acid, which was related to a significant RGR inhibition, where the specific photosynthetic structure area component was the most affected. Our results allowed determining that, despite the high tolerance to extreme temperatures described for Opuntia plants, young individuals of O. streptacantha suffered photosynthetic impairment that led to the inhibition of their growth. Thus, the main findings reported in this study can help to predict the potential impact of climatic change on the establishment and survival of succulent

  13. Growth and photosynthetic responses of two pine species (Pinus koraiensis and Pinus rigida) in a polluted industrial region in Korea

    International Nuclear Information System (INIS)

    Choi, D.S.; Kayama, M.; Jin, H.O.; Lee, C.H.; Izuta, T.; Koike, T.

    2006-01-01

    We investigated the effects of pollutants on two pine species (Pinus koraiensis and Pinus rigida) in an industrial region in Korea, using a physiological approach. The concentrations of fluorine (F) and chlorine (Cl) in the atmosphere, in precipitation and soil water at the damaged site were all significantly higher than at a control site. Moreover, the concentrations of F, Cl and Mn in pine needles were significantly higher, and essential elements and chlorophyll in needles were significantly lower at the damaged site than at the control site. The photosynthetic capacities, shoot length and survival statistics of needles of the two pines were all significantly reduced at the damaged site compared to the control site, especially P. rigida. Based on our comparison of photosynthetic responses and the concentrations of F, Cl and Mn in needles of the two pine species, P. koraiensis is more resistant to excess Mn in its needles than P. rigida. - Pinus koraiensis seems to be more pollution tolerant than Pinus rigida

  14. Differential sensitivity of light-harnessing photosynthetic events in wheat and sunflower to exogenously applied ionic and nanoparticulate silver.

    Science.gov (United States)

    Pardha-Saradhi, P; Shabnam, Nisha; Sharmila, P; Ganguli, Ashok K; Kim, Hyunook

    2018-03-01

    Potential impacts of inevitable leaks of silver nanoparticles (AgNPs) into environment on human beings need attention. Owing to the vitality of photosynthesis in maintaining life and ecosystem functioning, impacts of exogenously applied nanoparticulate and Ag + on photosystem (PS)II function, which governs overall photosynthesis, in wheat and sunflower were evaluated. PSII efficiency and related Chl a fluorescence kinetics of these two plants remained unaffected by AgNPs. However, Ag + caused a significant decline in the PSII activity and related fluorescence steps in wheat, but not in sunflower. Electron flow between Q A and PQ pool was found most sensitive to Ag + . Number of active reaction centers, electron transport, trapping of absorbed light for photochemistry, and performance index declined, while dissipation of absorbed light energy as heat significantly increased in wheat exposed to Ag + . Total antioxidant activity in sunflower was least affected by both Ag and AgNPs. In contrast, in the case of wheat, the antioxidant activity was declined by Ag + but not by AgNPs. Further, the amount of silver absorbed by plants exposed to Ag + was higher than that absorbed by plants exposed to AgNPs. While wheat retained majority of Ag in its roots, sunflower showed major Ag accumulation in stem. Photosynthetic events in sunflower, unlike wheat, were least affected as no detectable Ag levels was recorded in their leaves. Our findings revealed that AgNPs seemed non/less-toxic to light harnessing photosynthetic machinery of wheat, compared to Ag + . Photosynthetic events in sunflower were not affected by Ag + , either, as its translocation to leaves was restricted. Copyright © 2017. Published by Elsevier Ltd.

  15. [Flag leaf photosynthetic characteristics, change in chlorophyll fluorescence parameters, and their relationships with yield of winter wheat sowed in spring].

    Science.gov (United States)

    Xu, Lan; Gao, Zhi-qang; An, Wei; Li, Yan-liang; Jiao, Xiong-fei; Wang, Chuang-yun

    2016-01-01

    With five good winter wheat cultivars selected from the middle and lower reaches of Yangtze River and Southwest China as test materials, a field experiment in Xinding basin area of Shanxi Province was conducted to study the photosynthetic characteristics, chlorophyll content, and chlorophyll fluorescence parameters of flag leaf at different sowing dates, as well as the correlations between these indices and yield for two years (2013-2014). The results showed that the difference in most fluorescence parameters except chlorophyll content among cultivars was significant. The correlations between these fluorescence parameters and yield were significant. The variation coefficient of chlorophyll (Chl) content was low (0.12-0.17), and that of performance index based on absorption (PIabs) was high (0.32-0.39), with the partial correlation coefficients of them with grain yield from 2013 to 2014 ranged in 0.70-0.81. Under the early sowing condition, the grain yield positively correlated with PIabs at flowering and filling stages and chlorophyll content at grain filling stage, but negatively correlated with the relative variable fluorescence at I point (Vi) at grain filling stage. About 81.1%-82.8% of grain yield were determined by the variations of PIabs, Chl, and Vi. Wheat cultivars had various performances in the treatments with different sowing dates and a consistent trend was observed in the two experimental years. Among these 5 cultivars, Yangmai 13 was suitable for early sowing, with the flag leaf photosynthetic rate (Pn), Chl, most fluorescence parame-ters, and grain yield showed obviously high levels. In conclusion, under early sowing condition chlorophyll content at grain filling stages, PIabs at flowering and filling stages, and Pn were important indices for selecting wheat cultivars with high photosynthetic efficiency.

  16. Diurnal changes of photosynthetic quantum yield in the intertidal macroalga Sargassum thunbergii under simulated tidal emersion conditions

    Science.gov (United States)

    Yu, Yong Qiang; Zhang, Quan Sheng; Tang, Yong Zheng; Li, Xue Meng; Liu, Hong Liang; Li, Li Xia

    2013-07-01

    In this study, a three-way factorial experimental design was used to investigate the diurnal changes of photosynthetic activity of the intertidal macroalga Sargassum thunbergii in response to temperature, tidal pattern and desiccation during a simulated diurnal light cycle. The maximum (Fv/Fm) and effective (ΦPSII) quantum yields of photosystem II (PSII) were estimated by chlorophyll fluorescence using a pulse amplitude modulated fluorometer. Results showed that this species exhibited sun-adapted characteristics, as evidenced by the daily variation of Fv/Fm and ΦPSII. Both yield values decreased with increasing irradiance towards noon and recovered rapidly in the afternoon suggesting a dynamic photoinhibition. The photosynthetic quantum yield of S. thunbergii thalli varied significantly with temperature, tidal pattern and desiccation. Thalli were more susceptible to light-induced damage at high temperature of 25 °C and showed complete recovery of photosynthetic activity only when exposed to 8 °C. In contrast with the mid-morning low tide period, although there was an initial increase in photosynthetic yield during emersion, thalli showed a greater degree of decline at the end of emersion and remained less able to recover when low tide occurred at mid-afternoon. Short-term air exposure of 2 h did not significantly influence the photosynthesis. However, when exposed to moderate conditions (4 h desiccation at 15 °C or 6 h desiccation at 8 °C), a significant inhibition of photosynthesis was followed by partial or complete recovery upon re-immersion in late afternoon. Only extreme conditions (4 h desiccation at 25 °C or 6 h desiccation at 15 °C or 25 °C) resulted in the complete inhibition, with little indication of recovery until the following morning, implying the occurrence of chronic PSII damage. Based on the magnitude of effect, desiccation was the predominant negative factor affecting the photosynthesis under the simulated daytime irradiance period. These

  17. Global estimates of evapotranspiration and gross primary production based on MODIS and global meteorology data

    Science.gov (United States)

    Yuan, W.; Liu, S.; Yu, G.; Bonnefond, J.-M.; Chen, J.; Davis, K.; Desai, A.R.; Goldstein, Allen H.; Gianelle, D.; Rossi, F.; Suyker, A.E.; Verma, S.B.

    2010-01-01

    The simulation of gross primary production (GPP) at various spatial and temporal scales remains a major challenge for quantifying the global carbon cycle. We developed a light use efficiency model, called EC-LUE, driven by only four variables: normalized difference vegetation index (NDVI), photosynthetically active radiation (PAR), air temperature, and the Bowen ratio of sensible to latent heat flux. The EC-LUE model may have the most potential to adequately address the spatial and temporal dynamics of GPP because its parameters (i.e., the potential light use efficiency and optimal plant growth temperature) are invariant across the various land cover types. However, the application of the previous EC-LUE model was hampered by poor prediction of Bowen ratio at the large spatial scale. In this study, we substituted the Bowen ratio with the ratio of evapotranspiration (ET) to net radiation, and revised the RS-PM (Remote Sensing-Penman Monteith) model for quantifying ET. Fifty-four eddy covariance towers, including various ecosystem types, were selected to calibrate and validate the revised RS-PM and EC-LUE models. The revised RS-PM model explained 82% and 68% of the observed variations of ET for all the calibration and validation sites, respectively. Using estimated ET as input, the EC-LUE model performed well in calibration and validation sites, explaining 75% and 61% of the observed GPP variation for calibration and validation sites respectively.Global patterns of ET and GPP at a spatial resolution of 0.5° latitude by 0.6° longitude during the years 2000–2003 were determined using the global MERRA dataset (Modern Era Retrospective-Analysis for Research and Applications) and MODIS (Moderate Resolution Imaging Spectroradiometer). The global estimates of ET and GPP agreed well with the other global models from the literature, with the highest ET and GPP over tropical forests and the lowest values in dry and high latitude areas. However, comparisons with observed

  18. Fluorescence measurements show stronger cold inhibition of photosynthetic light reactions in Scots pine compared to Norway spruce as well as during spring compared to autumn.

    Science.gov (United States)

    Linkosalo, Tapio; Heikkinen, Juha; Pulkkinen, Pertti; Mäkipää, Raisa

    2014-01-01

    We studied the photosynthetic activity of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] Karst) in relation to air temperature changes from March 2013 to February 2014. We measured the chlorophyll fluorescence of approximately 50 trees of each species growing in southern Finland. Fluorescence was measured 1-3 times per week. We began by measuring shoots present in late winter (i.e., March 2013) before including new shoots once they started to elongate in spring. By July, when the spring shoots had achieved similar fluorescence levels to the older ones, we proceeded to measure the new shoots only. We analyzed the data by fitting a sigmoidal model containing four parameters to link sliding averages of temperature and fluorescence. A parameter defining the temperature range over which predicted fluorescence increased most rapidly was the most informative with in describing temperature dependence of fluorescence. The model generated similar fluorescence patterns for both species, but differences were observed for critical temperature and needle age. Down regulation of the light reaction was stronger in spring than in autumn. Pine showed more conservative control of the photosynthetic light reactions, which were activated later in spring and more readily attenuated in autumn. Under the assumption of a close correlation of fluorescence and photosynthesis, spruce should therefore benefit more than pine from the increased photosynthetic potential during warmer springs, but be more likely to suffer frost damage with a sudden cooling following a warm period. The winter of 2013-2014 was unusually mild and similar to future conditions predicted by global climate models. During the mild winter, the activity of photosynthetic light reactions of both conifers, especially spruce, remained high. Because light levels during winter are too low for photosynthesis, this activity may translate to a net carbon loss due to respiration.

  19. Fluorescence measurements show stronger cold inhibition of photosynthetic light reactions in Scots pine compared to Norway spruce as well as during spring compared to autumn

    Directory of Open Access Journals (Sweden)

    Tapio eLinkosalo

    2014-06-01

    Full Text Available We studied the photosynthetic activity of Scots pine (Pinus sylvestris L. and Norway spruce (Picea abies [L.] Karst in relation to air temperature changes from March 2013 to February 2014. We measured the chlorophyll fluorescence of approximately 50 trees of each species growing in southern Finland. Fluorescence was measured 13 times per week. We began by measuring shoots present in late winter (i.e., March 2013 before including new shoots once they started to elongate in spring. By July, when the spring shoots had achieved similar fluorescence levels to the older ones, we proceeded to measure the new shoots only.We analysed the data by fitting a sigmoidal model containing four parameters to link sliding averages of temperature and fluorescence. A parameter defining the temperature range over which predicted fluorescence increased most rapidly was the most informative with in describing temperature dependence of fluorescence.The model generated similar fluorescence patterns for both species, but differences were observed for critical temperature and needle age. Down regulation of the light reaction was stronger in spring than in autumn. Pine showed more conservative control of the photosynthetic light reactions, which were activated later in spring and more readily attenuated in autumn. Under the assumption of a close correlation of fluorescence and photosynthesis, spruce should therefore benefit more than pine from the increased photosynthetic potential during warmer springs, but be more likely to suffer frost damage with a sudden cooling following a warm period. The winter of 20132014 was unusually mild and similar to future conditions predicted by global warming models. During the mild winter, the activity of photosynthetic light reactions of both conifers, especially spruce, remained high. Because light levels during winter are too low for photosynthesis, this activity may translate to a net carbon loss due to respiration.

  20. Global Governance, Educational Change

    Science.gov (United States)

    Mundy, Karen

    2007-01-01

    In the last half decade, a rising literature has focused on the idea that processes of economic, political and social globalization require analysis in terms of governance at the global level. It is argued in this article that emerging forms of global governance have produced significant challenges to conventional conceptions of international…

  1. Diurnal changes of net photosynthetic rate (NPR) in leaves of Lonicera japonica Thunb. and the responding mathematical model of NPR to photosynthetic valid radiation

    International Nuclear Information System (INIS)

    Wu Dafu; Zhang Shengli; Li Dongfang

    2009-01-01

    [Objective] The study provided theoretical basis for production practice . [Method] With Lonicera japonica Thunb .as material, diurnal changes of net photosynthetic rate (NPR) in leaves of the plant and the responding mathematical model of NPR to photosynthetic valid radiation were studied using portable photosynthetic determinator system. [Result] Like most of C3 plants, the diurnal changes curve of NPR of Lonicera japonica Thunb .showed double peaks, but there were time difference in reaching the peak value between the study and previous ones . The responding mathematical model of NPR to photosynthetic valid radiation could be described by three mathematic functions, such as logarithm, linearity and binomial, but binomial function was more precise than the others. Light saturation point of Lonicera japonica Thunb. was figured out by binomial equation deduced in the study , and light saturation point was 1 086 .3 μmol/ (m2•s) . [Conclusion] The diurnal changes curve of NPR of Lonicera japonica Thunb .showed double peaks, and the responding mathematical model of NPR to photosynthetic valid radiation could be described by binomial functions

  2. Cotton growth potassium deficiency stress is influenced by photosynthetic apparatus and root system

    International Nuclear Information System (INIS)

    Hussain, Z.U.; Arshad, M.

    2010-01-01

    Due to rapid depletion of soil potassium (K) and increasing cost of K fertilizers in Pakistan, the K-use efficient crop genotypes become very important for agricultural sustain ability. However, limited research has been done on this important issue particularly in cotton, an important fibre crop. We studied the growth and biomass production of three cotton genotypes (CIM-506, NIAB- 78 and NIBGE-2) different in K-use efficiency in a K-deficient solution culture. Genotypes differed significantly for biomass production, absolute growth rates (shoot, root, leaf, total), leaf area, mean leaf area and relative growth rate of leaf under K deficiency stress, besides specific leaf area. The relative growth rate (shoot, root, total) did not differ significantly, except for leaf. For all these characters, NIBGE-2 was the best performer followed by NIAB-78 and CIM-506. Shoot dry weight was significantly related with (in decreasing order of significance): mean leaf area, leaf dry weight, leaf area, root dry weight, absolute growth rate of shoot, absolute growth rate of root, absolute growth rate total, absolute growth rate root, relative growth rate leaf, relative growth rate total and relative growth rate shoot. Hence, the enhanced biomass accumulation of cotton genotypes under K deficiency stress is related to their efficient photosynthetic apparatus and root system, appeared to be the most important morphological markers while breeding for K-use efficient cotton genotypes.(author)

  3. Atomic force microscopy studies of native photosynthetic membranes.

    Science.gov (United States)

    Sturgis, James N; Tucker, Jaimey D; Olsen, John D; Hunter, C Neil; Niederman, Robert A

    2009-05-05

    In addition to providing the earliest surface images of a native photosynthetic membrane at submolecular resolution, examination of the intracytoplasmic membrane (ICM) of purple bacteria by atomic force microscopy (AFM) has revealed a wide diversity of species-dependent arrangements of closely packed light-harvesting (LH) antennae, capable of fulfilling the basic requirements for efficient collection, transmission, and trapping of radiant energy. A highly organized architecture was observed with fused preparations of the pseudocrystalline ICM of Blastochloris viridis, consiting of hexagonally packed monomeric reaction center light-harvesting 1 (RC-LH1) core complexes. Among strains which also form a peripheral LH2 antenna, images of ICM patches from Rhodobacter sphaeroides exhibited well-ordered, interconnected networks of dimeric RC-LH1 core complexes intercalated by rows of LH2, coexisting with LH2-only domains. Other peripheral antenna-containing species, notably Rhodospirillum photometricum and Rhodopseudomonas palustris, showed a less regular organization, with mixed regions of LH2 and RC-LH1 cores, intermingled with large, paracrystalline domains. The ATP synthase and cytochrome bc(1) complex were not observed in any of these topographs and are thought to be localized in the adjacent cytoplasmic membrane or in inaccessible ICM regions separated from the flat regions imaged by AFM. The AFM images have served as a basis for atomic-resolution modeling of the ICM vesicle surface, as well as forces driving segregation of photosynthetic complexes into distinct domains. Docking of atomic-resolution molecular structures into AFM topographs of Rsp. photometricum membranes generated precise in situ structural models of the core complex surrounded by LH2 rings and a region of tightly packed LH2 complexes. A similar approach has generated a model of the highly curved LH2-only membranes of Rba. sphaeroides which predicts that sufficient space exists between LH2 complexes

  4. Adaptive changes in chlorophyll content and photosynthetic features to low light in Physocarpus amurensis Maxim and Physocarpus opulifolius "Diabolo".

    Science.gov (United States)

    Zhang, Huihui; Zhong, Haixiu; Wang, Jifeng; Sui, Xin; Xu, Nan

    2016-01-01

    The present study aims to investigate the differences in leaf pigment content and the photosynthetic characteristics under natural and low light intensities between the Chinese native Physocarpus amurensis Maxim and the imported Physocarpus opulifolius "Diabolo" from North America. We aim to discuss the responses and the adaptive mechanism of these two cultivars of Physocarpus to a low light environment. The results show that the specific leaf area (SLA) and the chlorophyll content were significantly increased in the leaves of both Physocarpus cultivars in response to a low light intensity, and the SLA and chlorophyll content were higher in the leaves of low light-treated P. opulifolius "Diabolo" compared with the leaves of low light-treated P. amurensis Maxim. Moreover, the content of anthocyanin was markedly reduced in the leaves of P. opulifolius "Diabolo" under low light intensity, which allowed for a greater capacity of photon capture under the low light condition. Under natural light, the photosynthetic carbon assimilation capacity was greater in the leaves of P. amurensis Maxim compared with the leaves of P. opulifolius "Diabolo" that were rich with anthocyanin. However, in response to low light, AQY, P max, LCP and LSP decreased to a lesser extent in the leaves of P. opulifolius "Diabolo" compared with the leaves of P. amurensis Maxim. These results suggest that P. opulifolius "Diabolo" exhibits a greater ability in adaption to low light, and it is probably related to the relatively higher chlorophyll content and the smaller SLA in the leaves of P. opulifolius "Diabolo." In addition, the low light intensity resulted in a reduced photochemical activity of photosystem (PS) II in the leaves of both Physocarpus, as evidenced by increased values of the relative variable fluorescence at point J and point I on the OJIP curve. This result suggests that the electron acceptor in PS II was the major responsive site to the low light stress in the leaves of both

  5. Needle age and season influence photosynthetic temperature response and total annual carbon uptake in mature Picea mariana trees

    Science.gov (United States)

    Jensen, Anna M.; Warren, Jeffrey M.; Hanson, Paul J.; Childs, Joanne; Wullschleger, Stan D.

    2015-01-01

    Background and Aims The carbon (C) balance of boreal terrestrial ecosystems is sensitive to increasing temperature, but the direction and thresholds of responses are uncertain. Annual C uptake in Picea and other evergreen boreal conifers is dependent on seasonal- and cohort-specific photosynthetic and respiratory temperature response functions, so this study examined the physiological significance of maintaining multiple foliar cohorts for Picea mariana trees within an ombrotrophic bog ecosystem in Minnesota, USA. Methods Measurements were taken on multiple cohorts of needles for photosynthetic capacity, foliar respiration (Rd) and leaf biochemistry and morphology of mature trees from April to October over 4 years. The results were applied to a simple model of canopy photosynthesis in order to simulate annual C uptake by cohort age under ambient and elevated temperature scenarios. Key Results Temperature responses of key photosynthetic parameters [i.e. light-saturated rate of CO2 assimilation (Asat), rate of Rubisco carboxylation (Vcmax) and electron transport rate (Jmax)] were dependent on season and generally less responsive in the developing current-year (Y0) needles compared with 1-year-old (Y1) or 2-year-old (Y2) foliage. Temperature optimums ranged from 18·7 to 23·7, 31·3 to 38·3 and 28·7 to 36·7 °C for Asat, Vcmax and Jmax, respectively. Foliar cohorts differed in their morphology and photosynthetic capacity, which resulted in 64 % of modelled annual stand C uptake from Y1&2 cohorts (LAI 0·67 m2 m−2) and just 36 % from Y0 cohorts (LAI 0·52 m2 m−2). Under warmer climate change scenarios, the contribution of Y0 cohorts was even less; e.g. 31 % of annual C uptake for a modelled 9 °C rise in mean summer temperatures. Results suggest that net annual C uptake by P. mariana could increase under elevated temperature, and become more dependent on older foliar cohorts. Conclusions Collectively, this study illustrates the physiological and

  6. Modulation of cadmium-induced phytotoxicity in Cabomba caroliniana by urea involves photosynthetic metabolism and antioxidant status.

    Science.gov (United States)

    Huang, Wenmin; Shao, Hui; Zhou, Sining; Zhou, Qin; Li, Wei; Xing, Wei

    2017-10-01

    Urea is a widespread organic pollutant, which can be a nitrogen source, playing different roles in the growth of submerged macrophytes depending on concentrations, while high cadmium (Cd) concentrations are often toxic to macrophytes. In order to evaluate the combined effect of urea and Cd on a submerged macrophyte, Cabomba caroliniana, the morphological and physiological responses of C. caroliniana in the presence of urea and Cd were studied. The results showed that high concentrations of urea (400mgL -1 ) and Cd (500µmolL -1 ) had negative effects on C. caroliniana. There were strong visible symptoms of toxicity after 4 days of exposure under Cd-alone, 400mgL -1 urea, and Cd+400mgL -1 urea treatments. In addition, 400mgL -1 urea and Cd had adverse effects on C. caroliniana's pigment system. Significant losses in chlorophyll fluorescence and photosynthetic rates, as well as Rubisco activity were also observed under Cd-alone, 400mgL -1 urea, and Cd+400mgL -1 urea treatments. 400mgL -1 urea markedly enhanced Cd toxicity in C. caroliniana, reflected by a sharp decrease in photosynthetic activity and more visible toxicity symptoms. The results of thiobarbituric acid reactive substances (TBARS) pointed to extreme oxidative stress in C. caroliniana induced under Cd or 400mgL -1 urea exposure. Exogenous ascorbate (AsA) protected C. caroliniana from adverse damage in 400mgL -1 urea, which further corroborated the oxidative stress claim under 400mgL -1 urea. However, results also demonstrated that lower urea concentration (10mgL -1 ) alleviated Cd-induced phytotoxicity by stimulating chlorophyll synthesis and photosynthetic activity, as well as activating the activity of catalase (CAT) and glutathione-S-transferase (GST), which may explain the alleviating effect of urea on C. caroliniana under Cd stress. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Impact of a cyclonic eddy on phytoplankton community structure and photosynthetic competency in the subtropical North Pacific Ocean

    Science.gov (United States)

    Vaillancourt, Robert D.; Marra, John; Seki, Michael P.; Parsons, Michael L.; Bidigare, Robert R.

    2003-07-01

    A synoptic spatial examination of the eddy Haulani (17-20 November 2000) revealed a structure typical of Hawaiian cyclonic eddies with divergent surface flow forcing the upward displacement of deep waters. Hydrographic surveys revealed that surface water in the eddy center was ca. 3.5°C cooler, 0.5 saltier, and 1.4 kg m -3 denser than surface waters outside the eddy. Vertically integrated concentrations of nitrate+nitrite, phosphate and silicate were enhanced over out-eddy values by about 2-fold, and nitrate+nitrite concentrations were ca. 8× greater within the euphotic zone inside the eddy than outside. Si:N ratios were lower within the upper mixed layer of the eddy, indicating an enhanced Si uptake relative to nitrate+nitrite. Chlorophyll a concentrations were higher within the eddy compared to control stations outside, when integrated over the upper 150 m, but were not significantly different when integrated over the depth of the euphotic zone. Photosynthetic competency, assessed using fast repetition-rate fluorometry, varied with the doming of the isopycnals and the supply of macro-nutrients to the euphotic zone. The physical and chemical environment of the eddy selected for the accumulation of larger phytoplankton species. Photosynthetic bacteria ( Prochlorococcus and Synechococcus) and small (3 μm diameter) were more abundant inside the eddy than outside. Diatoms of the genera Rhizosolenia and Hemiaulus outside the eddy contained diazotrophic endosymbiontic cyanobacteria, but these endosymbionts were absent from the cells of these species inside the eddy. The increase in cell numbers of large photosynthetic eukaryotes with hard silica or calcite cell walls is likely to have a profound impact on the proportion of the organic carbon production that is exported to deep water by sinking of senescent cells and cells grazed by herbivorous zooplankton and repackaged as large fecal pellets.

  8. Influence of TiO2 Nanoparticles on Growth and Phenolic Compounds Production in Photosynthetic Microorganisms

    Directory of Open Access Journals (Sweden)

    Mattia Comotto

    2014-01-01

    Full Text Available The influence of titanium dioxide nanoparticles (pure anatase and 15% N doped anatase on the growth of Chlorella vulgaris, Haematococcus pluvialis, and Arthrospira platensis was investigated. Results showed that pure anatase can lead to a significant growth inhibition of C. vulgaris and A. platensis (17.0 and 74.1%, resp., while for H. pluvialis the nanoparticles do not cause a significant inhibition. Since in these stress conditions photosynthetic microorganisms can produce antioxidant compounds in order to prevent cell damages, we evaluated the polyphenols content either inside the cells or released in the medium. Although results did not show a significant difference in C. vulgaris, the phenolic concentrations of two other microorganisms were statistically affected by the presence of titanium dioxide. In particular, 15% N doped anatase resulted in a higher production of extracellular antioxidant compounds, reaching the concentration of 65.2 and 68.0 mg gDB-1 for H. pluvialis and A. platensis, respectively.

  9. Combined effects of graphene oxide and Cd on the photosynthetic capacity and survival of Microcystis aeruginosa

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Yulin, E-mail: tangyulin@tongji.edu.cn; Tian, Jinglin; Li, Shuyan; Xue, Chonghua; Xue, Zhehua; Yin, Daqiang; Yu, Shuili

    2015-11-01

    In this work, the combined effects of graphene oxide (GO) and Cd{sup 2+} solution on Microcystis aeruginosa were investigated. Chlorophyll fluorescence parameters were measured by a pulse-amplitude modulated fluorometer. GO at low concentrations exhibited no significant toxicity. The presence of GO at low concentrations significantly enhanced Cd{sup 2+} toxicity as the 96 h half maximal effective concentration of the Cd{sup 2+} reduced from 0.51 ± 0.01 to 0.474 ± 0.01 mg/L. However, concentrations of GO above 5 mg/L did not significantly increase the toxicity of the Cd{sup 2+}/GO system. Observations through scanning and transmission electron microscopy revealed that GO, with Cd{sup 2+}, easily attached to and entered into the algae. Reactive oxygen species and malondialdehyde were measured to explain the toxicity mechanism. The photosynthetic parameters were useful in measuring the combined toxicity of the nanoparticles and heavy metals. - Highlights: • Combined effects of graphene oxide and Cd{sup 2+} to M. aeruginosa were investigated. • Chlorophyll fluorescence parameters were obtained by PAM. • OS and MDA were measured to evaluate algae toxicity. • GO at low concentration enhanced Cd{sup 2+} toxicity.

  10. RNA function and phosphorus use by photosynthetic organisms

    Directory of Open Access Journals (Sweden)

    John Albert Raven

    2013-12-01

    Full Text Available Phosphorus (P in RNA accounts for half or more of the total non-storage P in oxygenic photolithotrophs grown in either P-replete or P-limiting growth conditions. Since many natural environments are P-limited for photosynthetic primary productivity, and peak phosphorus fertilizer production is forecast for the next few decades, the paper analyses what economies in P allocation to RNA could, in principle, increase P use efficiency of growth (rate of dry matter production per unit organism P. The possibilities of decreasing P allocation to RNA without decreasing growth rate include a more widespread down-regulation of RNA production in P-limited organisms (as in the growth rate hypothesis, optimal allocation of P to RNA spatially among cell compartments and organs, and temporally depending on the stage of growth, and, for exponentially growing organisms with a constant fraction of P in RNA, a constant rate of protein synthesis through the diel cycle. Acting on these suggestions would be technically demanding, and could have unintended consequences for other aspect of metabolism.

  11. A multi-pathway model for photosynthetic reaction center

    International Nuclear Information System (INIS)

    Qin, M.; Shen, H. Z.; Yi, X. X.

    2016-01-01

    Charge separation occurs in a pair of tightly coupled chlorophylls at the heart of photosynthetic reaction centers of both plants and bacteria. Recently it has been shown that quantum coherence can, in principle, enhance the efficiency of a solar cell, working like a quantum heat engine. Here, we propose a biological quantum heat engine (BQHE) motivated by Photosystem II reaction center (PSII RC) to describe the charge separation. Our model mainly considers two charge-separation pathways which is more than that typically considered in the published literature. We explore how these cross-couplings increase the current and power of the charge separation and discuss the effects of multiple pathways in terms of current and power. The robustness of the BQHE against the charge recombination in natural PSII RC and dephasing induced by environments is also explored, and extension from two pathways to multiple pathways is made. These results suggest that noise-induced quantum coherence helps to suppress the influence of acceptor-to-donor charge recombination, and besides, nature-mimicking architectures with engineered multiple pathways for charge separations might be better for artificial solar energy devices considering the influence of environments.

  12. Hyperspectral estimation of corn fraction of photosynthetically active radiation

    International Nuclear Information System (INIS)

    Yang Fei; Zhang Bai; Song Kaishan

    2008-01-01

    Fraction of absorbed photosynthetically active radiation (FPAR) is one of the important variables in many productivity and biomass estimation models, this analyzed the effect of FPAR estimation with hyperspectral information, which could provide the scientific support on the improvement of FPAR estimation, remote sensing data validation, and the other ecological models. Based on the field experiment of corn, this paper analyzed the correlations between FPAR and spectral reflectance or the differential coefficient, and discussed the mechanism of FPAR estimation, studied corn FPAR estimation with reflectance, first differential coefficient, NDVI and RVI. The reflectance of visible bands showed much better correlations with FPAR than near-infrared bands. The correlation curve between FPAR and differential coefficient varied more frequently and greatly than the curve of FPAR and reflectance. Reflectance and differential coefficient both had good regressions with FPAR of the typical single band, with the maximum R2 of 0.791 and 0.882. In a word, differential coefficient and vegetation index were much effective than reflectance for corn FPAR estimating, and the stepwised regression of multibands differential coefficient showed the best regression with R2 of 0.944. 375 nm purpled band and 950 nm near-infraed band absorbed by water showed prodigious potential for FPAR estimating precision. On the whole, vegetation index and differential coefficient have good relationships with FPAR, and could be used for FAPR estimation. It would be effective of choosing right bands and excavating the hyperspectral data to improve FPAR estimating precision

  13. Mimicking the Role of the Antenna in Photosynthetic Photoprotection

    Energy Technology Data Exchange (ETDEWEB)

    Terazono, Yuichi; Kodis, Gerdenis; Bhushan, Kul; Zaks, Julia; Madden, Christopher; Moore, Ana L.; Moore, Thomas A.; Fleming, Graham R.; Gust, Devens

    2011-03-09

    One mechanism used by plants to protect against damage from excess sunlight is called nonphotochemical quenching (NPQ). Triggered by low pH in the thylakoid lumen, NPQ leads to conversion of excess excitation energy in the antenna system to heat before it can initiate production of harmful chemical species by photosynthetic reaction centers. Here we report a synthetic hexad molecule that functionally mimics the role of the antenna in NPQ. When the hexad is dissolved in an organic solvent, five zinc porphyrin antenna moieties absorb light, exchange excitation energy, and ultimately decay by normal photophysical processes. Their excited-state lifetimes are long enough to permit harvesting of the excitation energy for photoinduced charge separation or other work. However, when acid is added, a pH-sensitive dye moiety is converted to a form that rapidly quenches the first excited singlet states of all five porphyrins, converting the excitation energy to heat and rendering the porphyrins kinetically incompetent to readily perform useful photochemistry.

  14. Bacterial uptake of photosynthetic carbon from freshwater phytoplankton

    International Nuclear Information System (INIS)

    Coveney, M.F.

    1982-01-01

    Microheterotrophic uptake of algal extracellular products was studied in two eutrophic lakes in southern Sweden. Size fractionation was used in H 14 CO 3 uptake experiments to measure 14 C fixation in total particulate, small particulate and dissolved organic fractions. Carbon fixed in algal photosynthesis was recovered as dissolved and small particulate 14 C, representing excretion and bacterial uptake of algal products. Estimated gross extracellular release was low in these eutrophic systems, 1 to 7% of total 14 C uptake per m 2 lake surface. From 28 to 80 % of 14 C released was recovered in the small particulate fraction after ca. 4h incubation.This percentage was uniform within each depth profile, but varied directly with in situ water temperature. Laboratory time-series incubations indicated steady state for the pool of algal extracellular products on one occasion, while increasing pool size was indicated in the remaining two experiments. Uptake of photosynthetic carbon to small particles in situ was 32 to 95% of estimted heterotrophic bacterial production (as dark 14 CO 2 uptake) on four occasions. While excretion apparently was not an important loss of cabon for phytoplankton, it may have represented an important carbon source for planktonic bacteria. (author)

  15. Engineering biosynthesis of high-value compounds in photosynthetic organisms.

    Science.gov (United States)

    O'Neill, Ellis C; Kelly, Steven

    2017-09-01

    The photosynthetic, autotrophic lifestyle of plants and algae position them as ideal platform organisms for sustainable production of biomolecules. However, their use in industrial biotechnology is limited in comparison to heterotrophic organisms, such as bacteria and yeast. This usage gap is in part due to the challenges in generating genetically modified plants and algae and in part due to the difficulty in the development of synthetic biology tools for manipulating gene expression in these systems. Plant and algal metabolism, pre-installed with multiple biosynthetic modules for precursor compounds, bypasses the requirement to install these pathways in conventional production organisms, and creates new opportunities for the industrial production of complex molecules. This review provides a broad overview of the successes, challenges and future prospects for genetic engineering in plants and algae for enhanced or de novo production of biomolecules. The toolbox of technologies and strategies that have been used to engineer metabolism are discussed, and the potential use of engineered plants for industrial manufacturing of large quantities of high-value compounds is explored. This review also discusses the routes that have been taken to modify the profiles of primary metabolites for increasing the nutritional quality of foods as well as the production of specialized metabolites, cosmetics, pharmaceuticals and industrial chemicals. As the universe of high-value biosynthetic pathways continues to expand, and the tools to engineer these pathways continue to develop, it is likely plants and algae will become increasingly valuable for the biomanufacturing of high-value compounds.

  16. Manganese in photosynthetic oxygen evolution: An edge and EXAFS study

    International Nuclear Information System (INIS)

    Yachandra, V.K.; Guiles, R.D.; McDermott, A.; Britt, R.D.; Dexheimer, S.L.; Saver, K.; Klein, M.P.

    1985-01-01

    The authors edge studies have previously shown that the Mn edges in photosynthetic samples in the S 1 and S 2 states fall into the range for Mn III and Mn IV complexes, and that the K-edge energy increases appreciably on advancing S 1 to S 2 . This was the first evidence that manganese is directly involved in the storage of oxidizing equivalents. More recently, they have extended this result with better quality data from both spinach and a thermophilic cyanobacterium. The newer results show an interesting structure to the edges, including a 1s to 3d transition. The EXAFS results for spinach membranes show that the salient features of the Mn structure are the same in the S 1 and S 2 states. These features are a Mn neighbor at approx. =2.7 A and O or N neighbors at approx. =1.75 A and approx. =2.0 A. The EXAFS spectrum of the S 1 state of the thermophilic blue green algae are strikingly similar to that of spinach

  17. Protein translocons in photosynthetic organelles of Paulinella chromatophora

    Directory of Open Access Journals (Sweden)

    Przemysław Gagat

    2014-12-01

    Full Text Available The rhizarian amoeba Paulinella chromatophora harbors two photosynthetic cyanobacterial endosymbionts (chromatophores, acquired independently of primary plastids of glaucophytes, red algae and green plants. These endosymbionts have lost many essential genes, and transferred substantial number of genes to the host nuclear genome via endosymbiotic gene transfer (EGT, including those involved in photosynthesis. This indicates that, similar to primary plastids, Paulinella endosymbionts must have evolved a transport system to import their EGT-derived proteins. This system involves vesicular trafficking to the outer chromatophore membrane and presumably a simplified Tic-like complex at the inner chromatophore membrane. Since both sequenced Paulinella strains have been shown to undergo differential plastid gene losses, they do not have to possess the same set of Toc and Tic homologs. We searched the genome of Paulinella FK01 strain for potential Toc and Tic homologs, and compared the results with the data obtained for Paulinella CCAC 0185 strain, and 72 cyanobacteria, eight Archaeplastida as well as some other bacteria. Our studies revealed that chromatophore genomes from both Paulinella strains encode the same set of translocons that could potentially create a simplified but fully-functional Tic-like complex at the inner chromatophore membranes. The common maintenance of the same set of translocon proteins in two Paulinella strains suggests a similar import mechanism and/or supports the proposed model of protein import. Moreover, we have discovered a new putative Tic component, Tic62, a redox sensor protein not identified in previous comparative studies of Paulinella translocons.

  18. [Molecular, genetic and physiological analysis of photoinhibition and photosynthetic

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    A major goal of this project is to use a combined molecular genetic, biochemical and physiological approach to understand the relationship between photosynthetic performance and the structure of the multifunctional D1 reaction center protein of Photosystem II encoded by the chloroplast psbA gene. Relative to other chloroplast proteins, turover of D1 is rapid and highly light dependent and de novo synthesis of D1 is required for a plant's recovery from short term exposure to irradiances which induce photoinhibitory damage. These observations have led to models for a damage/repair cycle of PSII involving the targeted degradation and replacement of photodamaged D1. To investigate the effects of perturbing the D1 cycle on photosynthesis and autotrophic growth under high and low irradiance, we have examined the consequences of site-specific mutations of the psbA and 16S rRNA genes affecting synthesis, maturation and function/stability of the D1 protein introduced into the chloroplast genome of wildtype strain of the green alga Chlamydomonas reinhardtii using biolistic transformation.

  19. Importance of structure and density of macroalgae communities (Fucus serratus) for photosynthetic production and light utilisation

    DEFF Research Database (Denmark)

    Binzer, Thomas; Sand-Jensen, Kaj

    2002-01-01

    at high light depended on community density. Therefore, while the determination of the production of individual algal thalli is useful for evaluating differences in acclimatisation and adaptation between species and stands, it is not useful for evaluating production rates for entire plants and communities......Determination of photosynthetic production in plant communities is essential for evaluating plant growth rates and carbon fluxes in ecosystems, but it cannot easily be derived from the photosynthetic response of individual leaves or thalli, which has been the focus of virtually all previous aquatic...... studies. To evaluate the regulation of aquatic community production, we measured the photosynthetic production of thallus parts and entire communities of Fucus serratus (L.) of different density and spatial structure exposed to varying photon flux density and dissolved CO2 concentration. Photosynthetic...

  20. Using Phenomic Analysis of Photosynthetic Function for Abiotic Stress Response Gene Discovery

    KAUST Repository

    Rungrat, Tepsuda; Awlia, Mariam; Brown, Tim; Cheng, Riyan; Sirault, Xavier; Fajkus, Jiri; Trtilek, Martin; Furbank, Bob; Badger, Murray; Tester, Mark A.; Pogson, Barry J; Borevitz, Justin O; Wilson, Pip

    2016-01-01

    Monitoring the photosynthetic performance of plants is a major key to understanding how plants adapt to their growth conditions. Stress tolerance traits have a high genetic complexity as plants are constantly, and unavoidably, exposed to numerous

  1. Development of photosynthetic biofilms affected by dissolved and sorbed copper in a eutrophic river

    NARCIS (Netherlands)

    Barranguet, C.; Plans, M.; Van der Grinten, E.; Sinke, J.J.; Admiraal, W.

    2002-01-01

    Photosynthetic biofilms are capable of immobilizing important concentrations of metals, therefore reducing bioavailability to organisms. But also metal pollution is believed to produce changes in the microalgal species composition of biofilms. We investigated the changes undergone by natural

  2. Photosynthetically Available Radiation, Aqua MODIS, NPP, 0.125 degrees, East US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures photosynthetically available radiation that may be used to mode primary productivity. THIS IS AN EXPERIMENTAL PRODUCT: intended strictly for...

  3. Effect of Temperature and light intensity on growth and Photosynthetic Activity of Chlamydomonas reinhard II

    International Nuclear Information System (INIS)

    Alfonsel Jaen, M.; Fernandez Gonzalez, J.

    1985-01-01

    The effect of five temperatures (15,20,25,30 and 35 degree centigree) and two levels of illumination on growth and photosynthetic activity of Chlamydomonas reinhard II has been studied. The growth of the cultures was evaluated by optical density. Photosynthetic activity has been carried out studying either the assimilation rate of C0 2 labelled with C-14 or the oxygen evolution by means of polarographic measurements. The maximum photosynthetic rate has been obtained at 25 degree centigree for the lower level of illumination (2400 lux) and at 35 degree centigree for the higher one (13200 lux) and at 35 degree centigree for the higher ono (13200 lux). These results suggest an interaction of temperature and illumination on photosynthetic activity. (Author) 37 refs

  4. Improving Delivery of Photosynthetic Reducing Power to Cytochrome P450s

    DEFF Research Database (Denmark)

    Mellor, Silas Busck

    at sustainable production of high-value and commodity products. Cytochrome P450 enzymes play key roles in the biosynthesis of important natural products. The electron carrier ferredoxin can couple P450s non-natively to photosynthetic electron supply, providing ample reducing power for catalysis. However......, photosynthetic reducing power feeds into both central and specialized metabolism, which leads to a fiercely competitive system from which to siphon reductant. This thesis explores the optimization of light-driven P450 activity, and proposes strategies to overcome the limitations imposed by competition...... for photosynthetic reducing power. Photosynthetic electron carrier proteins interact with widely different partners because they use relatively non-specific interactions. The mechanistic basis of these interactions and its impact on natural electron transfer complexes is discussed. This particular type...

  5. Using a Microscale Approach to Rapidly Separate and Characterize Three Photosynthetic Pigment Species from Fern

    Science.gov (United States)

    Ayudhya, Theppawut Israsena Na; Posey, Frederick T.; Tyus, Jessica C.; Dingra, Nin N.

    2015-01-01

    A rapid separation of three photosynthetic pigments (chlorophyll "a" and "b" and xanthophyll) from fern ("Polystichum acrostichoides") is described using microscale solvent extraction and traditional thin layer chromatography that minimizes use of harmful chemicals and lengthy procedures. The experiment introduces…

  6. Polyhouse cultivation of invitro raised elite Stevia rebaudiana Bertoni: An assessment of biochemical and photosynthetic characteristics

    Science.gov (United States)

    Polyhouse cultivated Stevia rebaudiana Bertoni plants, initially raised from synthetic seeds, were assessed for biochemical and photosynthetic characteristics and compared with their mother plant. Synthetic seeds were produced using nodal segments containing single axillary buds excised from in vitr...

  7. Emerging experimental and computational technologies for purpose designed engineering of photosynthetic prokaryotes

    KAUST Repository

    Lindblad, Peter

    2016-01-01

    With recent advances in synthetic molecular tools to be used in photosynthetic prokaryotes, like cyanobacteria, it is possible to custom design and construct microbial cells for specific metabolic functions. This cross-disciplinary area of research

  8. Leaf development and photosynthetic properties of three tropical tree species with delayed greening

    NARCIS (Netherlands)

    Cai, Z.Q.; Slot, M.; Fan, Z.X.

    2005-01-01

    Leaf developmental patterns were characterized for three tropical tree species with delayed greening. Changes in the pigment contents, photosynthetic capacity, stomata development, photosystem 2 efficiency, rate of energy dissipation, and the activity of partial protective enzymes were followed in

  9. Specific Interaction between Redox Phospholipid Polymers and Plastoquinone in Photosynthetic Electron Transport Chain.

    Science.gov (United States)

    Tanaka, Kenya; Kaneko, Masahiro; Ishikawa, Masahito; Kato, Souichiro; Ito, Hidehiro; Kamachi, Toshiaki; Kamiya, Kazuhide; Nakanishi, Shuji

    2017-04-19

    Redox phospholipid polymers added in culture media are known to be capable of extracting electrons from living photosynthetic cells across bacterial cell membranes with high cytocompatibility. In the present study, we identify the intracellular redox species that transfers electrons to the polymers. The open-circuit electrochemical potential of an electrolyte containing the redox polymer and extracted thylakoid membranes shift to positive (or negative) under light irradiation, when an electron transport inhibitor specific to plastoquinone is added upstream (or downstream) in the photosynthetic electron transport chain. The same trend is also observed for a medium containing living photosynthetic cells of Synechococcus elongatus PCC7942. These results clearly indicate that the phospholipid redox polymers extract photosynthetic electrons mainly from plastoquinone. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Photosynthetic CO{sub 2} fixation and energy production - microalgae as a main subject

    Energy Technology Data Exchange (ETDEWEB)

    Asada, Yasuo [National Inst. of Bioscience and Human-Technology, Tsukuba-shi, Ibaraki-ken (Japan)

    1993-12-31

    Research activities for application of microalgal photosynthesis to CO{sub 2} fixation in Japan are overviewed. Presenter`s studies on energy (hydrogen gas) production by cyanobacteria (blue-green algae) and photosynthetic bacteria are also introduced.

  11. Photosynthetically Available Radiation, Aqua MODIS, NPP, 0.125 degrees, West US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures photosynthetically available radiation that may be used to mode primary productivity. THIS IS AN EXPERIMENTAL PRODUCT: intended strictly for...

  12. Photosynthetically Available Radiation, Aqua MODIS, NPP, 0.125 degrees, Gulf of Mexico

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures photosynthetically available radiation that may be used to mode primary productivity. THIS IS AN EXPERIMENTAL PRODUCT: intended strictly for...

  13. Effects of temperature and salinity on survival rate of cultured corals and photosynthetic efficiency of zooxanthellae in coral tissues

    Science.gov (United States)

    Kuanui, Pataporn; Chavanich, Suchana; Viyakarn, Voranop; Omori, Makoto; Lin, Chiahsin

    2015-06-01

    This study investigated the effects of temperature and salinity on growth, survival, and photosynthetic efficiency of three coral species, namely, Pocillopora damicornis, Acropora millepora and Platygyra sinensis of different ages (6 and 18 months old). The experimental corals were cultivated via sexual propagation. Colonies were exposed to 5 different temperatures (18, 23, 28, 33, and 38°C) and 5 different salinities (22, 27, 32, 37, and 42 psu). Results showed that temperature significantly affected photosynthetic efficiency (Fv/Fm) (p < 0.05) compared to salinity. The maximum quantum yield of corals decreased ranging from 5% to 100% when these corals were exposed to different temperatures and salinities. Temperature also significantly affected coral growth and survival. However, corals exposed to changes in salinity showed higher survivorship than those exposed to changes in temperature. Results in this study also showed that corals of different ages and of different species did not display the same physiological responses to changes in environmental conditions. Thus, the ability of corals to tolerate salinity and temperature stresses depends on several factors.

  14. Comparative Study on the Effect of Water Stress and Rootstock on Photosynthetic Function in Pistachio (Pistacia vera L. Trees

    Directory of Open Access Journals (Sweden)

    Abolfazl Ranjbar

    2017-12-01

    Full Text Available The aim of this study is to evaluate the  effects of water deficit stress on chlorophyll fluorescence (CF characteristics of photosystem II (PSII and pigment contents in two rootstock seedlings (Pistacia atlantica L. and P. khinjuk L.. Three levels of soil water potential (Ψs was used, including WWD (-0.05 MPa, MWD (-0.7 MPa and SWD (-1.5 MPa. It was found that water stress increased the minimal fluorescence (F0, quantum yield baseline (F0/Fm and decreased the maximal fluorescence (Fm and maximum quantum yield of PSII photochemistry (Fv/Fm parameters in dark adapted leaves. In light adapted leaves, a significant increase in non-photochemical quenching (NPQ and thermal dissipation of light energy to heat (D and a decrease in electron transport rate (ETR and photochemical efficiency of photosystem II (ΦPSII occurred. The results demonstrated a decline in photosynthetic pigments (Chla, (Chlb and carotenoids (Car content with increasing water stress, whereas there was no significant effect on Chl (a/b and Car/(a+b ratios. Our data revealed there was no different in terms of performance between the two rootstocks in the alteration rate of pigment contents and photosynthetic features against soil water deficit conditions.

  15. Comparison of net photosynthetic rate and 14C distribution between different cultural conditions on double cropping rice

    International Nuclear Information System (INIS)

    Huang Jianliang; Li Hesong; Zou Yingbin; Tu Naimei; Li Jianhui

    2002-01-01

    By applying the cultural method 'Vigorous Root-Strong Stem-Heavy Panicle Cultural Method' (VSHM), the yield of double cropping rice reached 18000 kg/hm 2 in large area at Liling county, Hunan province. The net photosynthetic rate and 14 C distribution of rice leaves between VSHM and traditional cultural methods (CK) were compared. The photosynthetic rate of the flag leaves at ripening stages under VSHM was higher than that of controls with both earlier rice or later rice. Regarding the net amount of 14 C-assimilate by a single flag leaf and the second top leaf, there were differences at the significant level of 0.01 and 0.05, respectively between VSHM and controls, and VSHM were 7.72%-35.05% higher. The percentage of distribution at panicles of 14 C-assimilate were 51.93%-61.40% when flag leaf was labelled, and 45.34%-54.25% when the second top leaf was labelled, that of earlier rice was higher than later rice respectively, but the differences were not significant between VSHM and CK. The actual yield of double cropping rice under the cultural condition of VSHM was 17710 kg/hm 2 , and increased by 18.33% when compared with controls

  16. Adverse effects of automobiles related PB/sup 2+/ pollution on photosynthetic attributes and water relations of roadside vegetation

    International Nuclear Information System (INIS)

    Ahmad, I.; Hussain, M.; Hameed, M.; Ahmad, R.

    2018-01-01

    This research was designed for the phyto-monitoring of Pb2+ pollution emitted from automobiles running along Motorway (M-2) and G.T. road and its effects on photosynthetic attributes and water relations of selected plant species growing along these roads. The data were collected from specified sites at different time intervals during all four seasons of the year. The results revealed significantly (p<0.05) higher Pb2+ content plant leaves growing in the vicinity of roadside (0 m distance) as compared to plant leaves collected from 50 m distance (Control) along both roads (M-2 and G.T. road). The leaves of Nerium oleander (2.45 mg kg-1 dry wt.) collected from M-2 trapped the higher amount of Pb2+ (p<0.001) at Kalar Kahar in Summer and Calotropis procera (2.78 mg kg-1 dry wt.) had the highest (p<0.05) Pb2+ deposition at Bahyria Town during summer. Photosynthetic rate, transpiration rate and stomatal conductance decreased significantly (p<0.01) in plants along roadsides; whereas, inconsistent results in water use efficiency were perceived in plants at 0 m distance as compared to those collected from 50 m distance. These outcomes are important to identify the existence of roadside vehicular pollutants on plants and to its ecological hazards. (author)

  17. Relationship between photosynthetic phosphorus-use efficiency and foliar phosphorus fractions in tropical tree species

    OpenAIRE

    Hidaka, Amane; Kitayama, Kanehiro

    2013-01-01

    How plants develop adaptive strategies to efficiently use nutrients on infertile soils is an important topic in plant ecology. It has been suggested that, with decreasing phosphorus (P) availability, plants increase photosynthetic P-use efficiency (PPUE) (i.e., the ratio of instantaneous photosynthetic carbon assimilation rate per unit foliar P). However, the mechanism to increase PPUE remains unclear. In this study, we tested whether high PPUE is explained by an optimized allocation of P in ...

  18. Fiber-optic fluorometer for microscale mapping of photosynthetic pigments in microbial communities

    DEFF Research Database (Denmark)

    Thar, Roland Matthias; Kühl, Michael; Holst, Gerhard

    2001-01-01

    Microscale fluorescence measurements were performed in photosynthetic biofilms at a spatial resolution of 100 to 200 µm with a new fiber-optic fluorometer which allowed four different excitation and emission wavelengths and was configured for measuring phycobiliproteins, chlorophylls, and bacteri......Microscale fluorescence measurements were performed in photosynthetic biofilms at a spatial resolution of 100 to 200 µm with a new fiber-optic fluorometer which allowed four different excitation and emission wavelengths and was configured for measuring phycobiliproteins, chlorophylls...