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Sample records for acquired photosynthetic traits

  1. Reverse evolution: driving forces behind the loss of acquired photosynthetic traits.

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    Francisco de Castro

    Full Text Available The loss of photosynthesis has occurred often in eukaryotic evolution, even more than its acquisition, which occurred at least nine times independently and which generated the evolution of the supergroups Archaeplastida, Rhizaria, Chromalveolata and Excavata. This secondary loss of autotrophic capability is essential to explain the evolution of eukaryotes and the high diversity of protists, which has been severely underestimated until recently. However, the ecological and evolutionary scenarios behind this evolutionary "step back" are still largely unknown.Using a dynamic model of heterotrophic and mixotrophic flagellates and two types of prey, large bacteria and ultramicrobacteria, we examine the influence of DOC concentration, mixotroph's photosynthetic growth rate, and external limitations of photosynthesis on the coexistence of both types of flagellates. Our key premises are: large bacteria grow faster than small ones at high DOC concentrations, and vice versa; and heterotrophic flagellates are more efficient than the mixotrophs grazing small bacteria (both empirically supported. We show that differential efficiency in bacteria grazing, which strongly depends on cell size, is a key factor to explain the loss of photosynthesis in mixotrophs (which combine photosynthesis and bacterivory leading to purely heterotrophic lineages. Further, we show in what conditions an heterotroph mutant can coexist, or even out-compete, its mixotrophic ancestor, suggesting that bacterivory and cell size reduction may have been major triggers for the diversification of eukaryotes.Our results suggest that, provided the mixotroph's photosynthetic advantage is not too large, the (small heterotroph will also dominate in nutrient-poor environments and will readily invade a community of mixotrophs and bacteria, due to its higher efficiency exploiting the ultramicrobacteria. As carbon-limited conditions were presumably widespread throughout Earth history, such a

  2. Height-related changes in leaf photosynthetic traits in diverse Bornean tropical rain forest trees.

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    Kenzo, Tanaka; Inoue, Yuta; Yoshimura, Mitsunori; Yamashita, Megumi; Tanaka-Oda, Ayumi; Ichie, Tomoaki

    2015-01-01

    Knowledge of variations in morphophysiological leaf traits with forest height is essential for quantifying carbon and water fluxes from forest ecosystems. Here, we examined changes in leaf traits with forest height in diverse tree species and their role in environmental acclimation in a tropical rain forest in Borneo that does not experience dry spells. Height-related changes in leaf physiological and morphological traits [e.g., maximum photosynthetic rate (Amax), stomatal conductance (gs), dark respiration rate (Rd), carbon isotope ratio (δ(13)C), nitrogen (N) content, and leaf mass per area (LMA)] from understory to emergent trees were investigated in 104 species in 29 families. We found that many leaf area-based physiological traits (e.g., A(max-area), Rd, gs), N, δ(13)C, and LMA increased linearly with tree height, while leaf mass-based physiological traits (e.g., A(max-mass)) only increased slightly. These patterns differed from other biomes such as temperate and tropical dry forests, where trees usually show decreased photosynthetic capacity (e.g., A(max-area), A(max-mass)) with height. Increases in photosynthetic capacity, LMA, and δ(13)C are favored under bright and dry upper canopy conditions with higher photosynthetic productivity and drought tolerance, whereas lower R d and LMA may improve shade tolerance in lower canopy trees. Rapid recovery of leaf midday water potential to theoretical gravity potential during the night supports the idea that the majority of trees do not suffer from strong drought stress. Overall, leaf area-based photosynthetic traits were associated with tree height and the degree of leaf drought stress, even in diverse tropical rain forest trees.

  3. A Bias for the Natural? Children's Beliefs about Traits Acquired through Effort, Bribes, or Medicine

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    Lockhart, Kristi L.; Keil, Frank C.; Aw, Justine

    2013-01-01

    Three studies compared beliefs about natural and late blooming positive traits with those acquired through personal effort, extrinsic rewards or medicine. Young children (5-6 years), older children (8-13 years), and adults all showed a strong bias for natural and late blooming traits over acquired traits. All age groups, except 8- to 10-year-olds,…

  4. A Bias for the Natural? Children's Beliefs about Traits Acquired through Effort, Bribes, or Medicine

    Science.gov (United States)

    Lockhart, Kristi L.; Keil, Frank C.; Aw, Justine

    2013-01-01

    Three studies compared beliefs about natural and late blooming positive traits with those acquired through personal effort, extrinsic rewards or medicine. Young children (5-6 years), older children (8-13 years), and adults all showed a strong bias for natural and late blooming traits over acquired traits. All age groups, except 8- to 10-year-olds,…

  5. Higher photosynthetic capacity and different functional trait scaling relationships in erect bryophytes compared with prostrate species.

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    Wang, Zhe; Liu, Xin; Bao, Weikai

    2016-02-01

    Ecophysiological studies of bryophytes have generally been conducted at the shoot or canopy scale. However, their growth forms are diverse, and knowledge of whether bryophytes with different shoot structures have different functional trait levels and scaling relationships is limited. We collected 27 bryophyte species and categorised them into two groups based on their growth forms: erect and prostrate species. Twenty-one morphological, nutrient and photosynthetic traits were quantified. Trait levels and bivariate trait scaling relationships across species were compared between the two groups. The two groups had similar mean values for shoot mass per area (SMA), light saturation point and mass-based nitrogen (N(mass)) and phosphorus concentrations. Erect bryophytes possessed higher values for mass-based chlorophyll concentration (Chl(mass)), light-saturated assimilation rate (A(mass)) and photosynthetic nitrogen/phosphorus use efficiency. N(mass), Chl(mass) and A(mass) were positively related, and these traits were negatively associated with SMA. Furthermore, the slope of the regression of N(mass) versus Chl(mass) was steeper for erect bryophytes than that for prostrate bryophytes, whereas this pattern was reversed for the relationship between Chl(mass) and A(mass). In conclusion, erect bryophytes possess higher photosynthetic capacities than prostrate species. Furthermore, erect bryophytes invest more nitrogen in chloroplast pigments to improve their light-harvesting ability, while the structure of prostrate species permits more efficient light capture. This study confirms the effect of growth form on the functional trait levels and scaling relationships of bryophytes. It also suggests that bryophytes could be good models for investigating the carbon economy and nutrient allocation of plants at the shoot rather than the leaf scale.

  6. Homophily and the Speed of Social Mobilization: The Effect of Acquired and Ascribed Traits

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    Alstott, Jeff; Velu, Chander

    2014-01-01

    Large-scale mobilization of individuals across social networks is becoming increasingly prevalent in society. However, little is known about what affects the speed of social mobilization. Here we use a framed field experiment to identify and measure properties of individuals and their relationships that predict mobilization speed. We ran a global social mobilization contest and recorded personal traits of the participants and those they recruited. We studied the effects of ascribed traits (gender, age) and acquired traits (geography, and information source) on the speed of mobilization. We found that homophily, a preference for interacting with other individuals with similar traits, had a mixed role in social mobilization. Homophily was present for acquired traits, in which mobilization speed was faster when the recuiter and recruit had the same trait compared to different traits. In contrast, we did not find support for homophily for the ascribed traits. Instead, those traits had other, non-homophily effects...

  7. Low temperature wheat germplasm and its leaf photosynthetic traits and structure characteristics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Songwu; MIAO Fang; WANG Changfa

    2004-01-01

    Low temperature germplasm with constant low plant temperature was found in the nature through a long-time observation on wheat canopy temperature and traits; correspondingly, high temperature germplasm with constant high plant temperature also exists. Compared with the high temperature germplasm, the chlorophyll content and the net photosynthetic rate of the three functional leaves on the top of the low temperature wheat germplasm are higher and the structure tends to be more complicated, which is characterized by smaller mesophyll cells and more closely arranged cell layers, more and denser chloroplasts with thick stroma, more granas and well developed grana lamellae, a larger vascular bundle area with smaller interspace. All these characteristics embody the consistency of structure and function and provide the theoretical bases for looking for and cultivating the new low temperature materials in agricultural practice.

  8. EFFECT OF PLANT DENSITY ON AGRONOMIC TRAITS AND PHOTOSYNTHETIC PERFORMANCE IN THE MAIZE IBM POPULATION

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    Mario Franić

    2015-12-01

    Full Text Available Photosynthesis is a vital process in plant physiology. Performance index is an indicator of plant vitality and is used as a main parameter in chlorophyll fluorescence measurements. Plant density is an important factor in maize production that can affect grain yield. Objective of this paper was to estimate the effect of plant density on agronomic traits and photosynthetic efficiency in the maize IBM population. The results showed a decrease in grain yield per plant basis (20 plants per plot in higher plant density (normal density - 3.88 kg per plot, high density - 2.95 kg per plot and an increase in grain yield per unit area (yield/ha in higher plant density (normal density - 11.03t ha-1, high density - 13.64 t ha-1. Performance index was decreased in higher plant density (normal density - 5.31, high density - 4.95. Statistical analysis showed highly significant effect (p<0.001 of density on performance index and highly significant effects (p<0.001 of plant density and genotype on maize yield. Low positive correlation was observed between grain yield per plot and performance index (r = 0.36, p<0.001.

  9. How trait anxiety, interpretation bias and memory affect acquired fear in children learning about new animals.

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    Field, Zoë C; Field, Andy P

    2013-06-01

    Cognitive models of vulnerability to anxiety propose that information processing biases such as interpretation bias play a part in the etiology and maintenance of anxiety disorders. However, at present little is known about the role of memory in information processing accounts of child anxiety. The current study investigates the relationships between interpretation biases, memory and fear responses when learning about new stimuli. Children (aged 8-11 years) were presented with ambiguous information regarding a novel animal, and their fear, interpretation bias, and memory for the information was measured. The main findings were: (1) trait anxiety and interpretation bias significantly predicted acquired fear; (2) interpretation bias did not significantly mediate the relationship between trait anxiety and acquired fear; (3) interpretation bias appeared to be a more important predictor of acquired fear than trait anxiety per se; and (4) the relationship between interpretation bias and acquired fear was not mediated by the number of negative memories but was mediated by the number of positive and false-positive memories. The findings suggest that information processing models of child anxiety need to explain the role of positive memory in the formation of fear responses.

  10. The photosynthetic capacity in 35 ferns and fern allies: mesophyll CO2 diffusion as a key trait.

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    Tosens, Tiina; Nishida, Keisuke; Gago, Jorge; Coopman, Rafael Eduardo; Cabrera, Hernán Marino; Carriquí, Marc; Laanisto, Lauri; Morales, Loreto; Nadal, Miquel; Rojas, Roke; Talts, Eero; Tomas, Magdalena; Hanba, Yuko; Niinemets, Ülo; Flexas, Jaume

    2016-03-01

    Ferns and fern allies have low photosynthetic rates compared with seed plants. Their photosynthesis is thought to be limited principally by physical CO2 diffusion from the atmosphere to chloroplasts. The aim of this study was to understand the reasons for low photosynthesis in species of ferns and fern allies (Lycopodiopsida and Polypodiopsida). We performed a comprehensive assessment of the foliar gas-exchange and mesophyll structural traits involved in photosynthetic function for 35 species of ferns and fern allies. Additionally, the leaf economics spectrum (the interrelationships between photosynthetic capacity and leaf/frond traits such as leaf dry mass per unit area or nitrogen content) was tested. Low mesophyll conductance to CO2 was the main cause for low photosynthesis in ferns and fern allies, which, in turn, was associated with thick cell walls and reduced chloroplast distribution towards intercellular mesophyll air spaces. Generally, the leaf economics spectrum in ferns follows a trend similar to that in seed plants. Nevertheless, ferns and allies had less nitrogen per unit DW than seed plants (i.e. the same slope but a different intercept) and lower photosynthesis rates per leaf mass area and per unit of nitrogen.

  11. Water relations traits of C4 grasses depend on phylogenetic lineage, photosynthetic pathway, and habitat water availability.

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    Liu, Hui; Osborne, Colin P

    2015-02-01

    The repeated evolution of C4 photosynthesis in independent lineages has resulted in distinct biogeographical distributions in different phylogenetic lineages and the variants of C4 photosynthesis. However, most previous studies have only considered C3/C4 differences without considering phylogeny, C4 subtype, or habitat characteristics. We hypothesized that independent lineages of C4 grasses have structural and physiological traits that adapt them to environments with differing water availability. We measured 40 traits of 33 species from two major C4 grass lineages in a common glasshouse environment. Chloridoideae species were shorter, with narrower and longer leaves, smaller but denser stomata, and faster curling leaves than Panicoideae species, but overall differences in leaf hydraulic and gas exchange traits between the two lineages were weak. Chloridoideae species had two different ways to reach higher drought resistance potential than Panicoideae; NAD-ME species used water saving, whereas PCK species used osmotic adjustment. These patterns could be explained by the interactions of lineage×C4 subtype and lineage×habitat water availability in affected traits. Specifically, phylogeny tended to have a stronger influence on structural traits, and C4 subtype had more important effects on physiological traits. Although hydraulic traits did not differ consistently between lineages, they showed strong covariation and relationships with leaf structure. Thus, phylogenetic lineage, photosynthetic pathway, and adaptation to habitat water availability act together to influence the leaf water relations traits of C4 grasses. This work expands our understanding of ecophysiology in major C4 grass lineages, with implications for explaining their regional and global distributions in relation to climate.

  12. Water relations traits of C4 grasses depend on phylogenetic lineage, photosynthetic pathway, and habitat water availability

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    Liu, Hui; Osborne, Colin P.

    2015-01-01

    The repeated evolution of C4 photosynthesis in independent lineages has resulted in distinct biogeographical distributions in different phylogenetic lineages and the variants of C4 photosynthesis. However, most previous studies have only considered C3/C4 differences without considering phylogeny, C4 subtype, or habitat characteristics. We hypothesized that independent lineages of C4 grasses have structural and physiological traits that adapt them to environments with differing water availability. We measured 40 traits of 33 species from two major C4 grass lineages in a common glasshouse environment. Chloridoideae species were shorter, with narrower and longer leaves, smaller but denser stomata, and faster curling leaves than Panicoideae species, but overall differences in leaf hydraulic and gas exchange traits between the two lineages were weak. Chloridoideae species had two different ways to reach higher drought resistance potential than Panicoideae; NAD-ME species used water saving, whereas PCK species used osmotic adjustment. These patterns could be explained by the interactions of lineage×C4 subtype and lineage×habitat water availability in affected traits. Specifically, phylogeny tended to have a stronger influence on structural traits, and C4 subtype had more important effects on physiological traits. Although hydraulic traits did not differ consistently between lineages, they showed strong covariation and relationships with leaf structure. Thus, phylogenetic lineage, photosynthetic pathway, and adaptation to habitat water availability act together to influence the leaf water relations traits of C4 grasses. This work expands our understanding of ecophysiology in major C4 grass lineages, with implications for explaining their regional and global distributions in relation to climate. PMID:25504656

  13. Estimating Plant Traits of Grasslands from UAV-Acquired Hyperspectral Images: A Comparison of Statistical Approaches

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    Alessandra Capolupo

    2015-12-01

    Full Text Available Grassland ecosystems cover around 40% of the entire Earth’s surface. Therefore, it is necessary to guarantee good grassland management at field scale in order to improve its conservation and to achieve optimal growth. This study identified the most appropriate statistical strategy, between partial least squares regression (PLSR and narrow vegetation indices, for estimating the structural and biochemical grassland traits from UAV-acquired hyperspectral images. Moreover, the influence of fertilizers on plant traits for grasslands was analyzed. Hyperspectral data were collected from an experimental field at the farm Haus Riswick, near Kleve in Germany, for two different flight campaigns in May and October. The collected image blocks were geometrically and radiometrically corrected for surface reflectance. Spectral signatures extracted for the plots were adopted to derive grassland traits by computing PLSR and the following narrow vegetation indices: the MERIS Terrestrial Chlorophyll Index (MTCI, the ratio of the Modified Chlorophyll Absorption in Reflectance and Optimized Soil-Adjusted Vegetation Index (MCARI/OSAVI modified by Wu, the Red-edge Chlorophyll Index (CIred-edge, and the Normalized Difference Red Edge (NDRE. PLSR showed promising results for estimating grassland structural traits and gave less satisfying outcomes for the selected chemical traits (crude ash, crude fiber, crude protein, Na, K, metabolic energy. Established relations are not influenced by the type and the amount of fertilization, while they are affected by the grassland health status. PLSR is found to be the best strategy, among the approaches analyzed in this paper, for exploring structural and biochemical features of grasslands. Using UAV-based hyperspectral sensing allows for the highly detailed assessment of grassland experimental plots.

  14. Ancestral genes can control the ability of horizontally acquired loci to confer new traits.

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    H Deborah Chen

    2011-07-01

    Full Text Available Horizontally acquired genes typically function as autonomous units conferring new abilities when introduced into different species. However, we reasoned that proteins preexisting in an organism might constrain the functionality of a horizontally acquired gene product if it operates on an ancestral pathway. Here, we determine how the horizontally acquired pmrD gene product activates the ancestral PmrA/PmrB two-component system in Salmonella enterica but not in the closely related bacterium Escherichia coli. The Salmonella PmrD protein binds to the phosphorylated PmrA protein (PmrA-P, protecting it from dephosphorylation by the PmrB protein. This results in transcription of PmrA-dependent genes, including those conferring polymyxin B resistance. We now report that the E. coli PmrD protein can activate the PmrA/PmrB system in Salmonella even though it cannot do it in E. coli, suggesting that these two species differ in an additional component controlling PmrA-P levels. We establish that the E. coli PmrB displays higher phosphatase activity towards PmrA-P than the Salmonella PmrB, and we identified a PmrB subdomain responsible for this property. Replacement of the E. coli pmrB gene with the Salmonella homolog was sufficient to render E. coli resistant to polymyxin B under PmrD-inducing conditions. Our findings provide a singular example whereby quantitative differences in the biochemical activities of orthologous ancestral proteins dictate the ability of a horizontally acquired gene product to confer species-specific traits. And they suggest that horizontally acquired genes can potentiate selection at ancestral loci.

  15. Characterization and molecular interpretation of the photosynthetic traits of Lonicera confusa in Karst environment.

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    Geng Wu

    Full Text Available Lonicera confusa was a medical plant which could adapt to the Ca-rich environment in the karst area of China. The photosynthesis, relative chlorophyll content,differentially expressed genes (DEGs and differentially expressed proteins (DEPs of L. confusa that cultivated in calcareous and sandstone soils were investigated. The results showed that the relative chlorophyll content and net photosynthesis rate of L. confusa in calcareous soil are much higher than that planted in sandstone soil, the higher content of calcium might play a role in keeping the chloroplast from harm and showed higher photosynthesis rate. The transpiration and stomata conductance were decreased in calcareous soil, which might result from the closure of stomata. The GeneFishing and proteomic results showed that the expression of DEGs and DEPs were critical for photosynthesis and stomata closure, such as RuBisCO, photosynthetic electron transfer c and malate dehydrogenase varied in the leaves of L. confusa that cultivated in different soils. These DEGs or DEPs were further found to be directly or indirectly regulated by calcium sensor proteins. This study enriched our knowledge of the molecular mechanism of high net photosynthesis rate and lower transpiration of L. confusa that cultivated in the calcareous soil in some degree.

  16. Changes in Leaf Anatomical Traits Enhanced Photosynthetic Activity of Soybean Grown in Hydroponics with Plant Growth-Promoting Microorganisms.

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    Paradiso, Roberta; Arena, Carmen; De Micco, Veronica; Giordano, Maria; Aronne, Giovanna; De Pascale, Stefania

    2017-01-01

    The use of hydroponic systems for cultivation in controlled climatic conditions and the selection of suitable genotypes for the specific environment help improving crop growth and yield. We hypothesized that plant performance in hydroponics could be further maximized by exploiting the action of plant growth-promoting organisms (PGPMs). However, the effects of PGPMs on plant physiology have been scarcely investigated in hydroponics. Within a series of experiments aimed to identify the best protocol for hydroponic cultivation of soybean [Glycine max (L.) Merr.], we evaluated the effects of a PGPMs mix, containing bacteria, yeasts, mycorrhiza and trichoderma beneficial species on leaf anatomy, photosynthetic activity and plant growth of soybean cv. 'Pr91m10' in closed nutrient film technique (NFT). Plants were grown in a growth chamber under semi-aseptic conditions and inoculated at seed, seedling and plant stages, and compared to non-inoculated (control) plants. Light and epi-fluorescence microscopy analyses showed that leaves of inoculated plants had higher density of smaller stomata (297 vs. 247 n/mm(2)), thicker palisade parenchyma (95.0 vs. 85.8 μm), and larger intercellular spaces in the mesophyll (57.5% vs. 52.2%), compared to non-inoculated plants. The modifications in leaf functional anatomical traits affected gas exchanges; in fact starting from the reproductive phase, the rate of leaf net photosynthesis (NP) was higher in inoculated compared to control plants (8.69 vs. 6.13 μmol CO2 m(-2) s(-1) at the beginning of flowering). These data are consistent with the better maximal PSII photochemical efficiency observed in inoculated plants (0.807 vs. 0.784 in control); conversely no difference in leaf chlorophyll content was found. The PGPM-induced changes in leaf structure and photosynthesis lead to an improvement of plant growth (+29.9% in plant leaf area) and seed yield (+36.9%) compared to control. Our results confirm that PGPMs may confer benefits in

  17. Changes in Leaf Anatomical Traits Enhanced Photosynthetic Activity of Soybean Grown in Hydroponics with Plant Growth-Promoting Microorganisms

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    Roberta Paradiso

    2017-05-01

    Full Text Available The use of hydroponic systems for cultivation in controlled climatic conditions and the selection of suitable genotypes for the specific environment help improving crop growth and yield. We hypothesized that plant performance in hydroponics could be further maximized by exploiting the action of plant growth-promoting organisms (PGPMs. However, the effects of PGPMs on plant physiology have been scarcely investigated in hydroponics. Within a series of experiments aimed to identify the best protocol for hydroponic cultivation of soybean [Glycine max (L. Merr.], we evaluated the effects of a PGPMs mix, containing bacteria, yeasts, mycorrhiza and trichoderma beneficial species on leaf anatomy, photosynthetic activity and plant growth of soybean cv. ‘Pr91m10’ in closed nutrient film technique (NFT. Plants were grown in a growth chamber under semi-aseptic conditions and inoculated at seed, seedling and plant stages, and compared to non-inoculated (control plants. Light and epi-fluorescence microscopy analyses showed that leaves of inoculated plants had higher density of smaller stomata (297 vs. 247 n/mm2, thicker palisade parenchyma (95.0 vs. 85.8 μm, and larger intercellular spaces in the mesophyll (57.5% vs. 52.2%, compared to non-inoculated plants. The modifications in leaf functional anatomical traits affected gas exchanges; in fact starting from the reproductive phase, the rate of leaf net photosynthesis (NP was higher in inoculated compared to control plants (8.69 vs. 6.13 μmol CO2 m-2 s-1 at the beginning of flowering. These data are consistent with the better maximal PSII photochemical efficiency observed in inoculated plants (0.807 vs. 0.784 in control; conversely no difference in leaf chlorophyll content was found. The PGPM-induced changes in leaf structure and photosynthesis lead to an improvement of plant growth (+29.9% in plant leaf area and seed yield (+36.9% compared to control. Our results confirm that PGPMs may confer benefits in

  18. Effects of atmospheric CO2 concentration, irradiance, and soil nitrogen availability on leaf photosynthetic traits of Polygonum sachalinense around natural CO2 springs in northern Japan.

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    Osada, Noriyuki; Onoda, Yusuke; Hikosaka, Kouki

    2010-09-01

    Long-term exposure to elevated CO2 concentration will affect the traits of wild plants in association with other environmental factors. We investigated multiple effects of atmospheric CO2 concentration, irradiance, and soil N availability on the leaf photosynthetic traits of a herbaceous species, Polygonum sachalinense, growing around natural CO2 springs in northern Japan. Atmospheric CO2 concentration and its interaction with irradiance and soil N availability affected several leaf traits. Leaf mass per unit area increased and N per mass decreased with increasing CO2 and irradiance. Leaf N per area increased with increasing soil N availability at higher CO2 concentrations. The photosynthetic rate under growth CO2 conditions increased with increasing irradiance and CO2, and with increasing soil N at higher CO2 concentrations. The maximal velocity of ribulose 1,5-bisphosphate carboxylation (V (cmax)) was affected by the interaction of CO2 and soil N, suggesting that down-regulation of photosynthesis at elevated CO2 was more evident at lower soil N availability. The ratio of the maximum rate of electron transport to V (cmax) (J (max)/V (cmax)) increased with increasing CO2, suggesting that the plants used N efficiently for photosynthesis at high CO2 concentrations by changes in N partitioning. To what extent elevated CO2 influenced plant traits depended on other environmental factors. As wild plants are subject to a wide range of light and nutrient availability, our results highlight the importance of these environmental factors when the effects of elevated CO2 on plants are evaluated.

  19. A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling.

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    Galmés, Jeroni; Hermida-Carrera, Carmen; Laanisto, Lauri; Niinemets, Ülo

    2016-09-01

    The present study provides a synthesis of the in vitro and in vivo temperature responses of Rubisco Michaelis-Menten constants for CO2 (Kc) and O2 (Ko), specificity factor (Sc,o) and maximum carboxylase turnover rate (kcatc) for 49 species from all the main photosynthetic kingdoms of life. Novel correction routines were developed for in vitro data to remove the effects of study-to-study differences in Rubisco assays. The compilation revealed differences in the energy of activation (∆Ha) of Rubisco kinetics between higher plants and other photosynthetic groups, although photosynthetic bacteria and algae were under-represented and very few species have been investigated so far. Within plants, the variation in Rubisco temperature responses was related to species' climate and photosynthetic mechanism, with differences in ∆Ha for kcatc among C3 plants from cool and warm environments, and in ∆Ha for kcatc and Kc among C3 and C4 plants. A negative correlation was observed among ∆Ha for Sc/o and species' growth temperature for all data pooled, supporting the convergent adjustment of the temperature sensitivity of Rubisco kinetics to species' thermal history. Simulations of the influence of varying temperature dependences of Rubisco kinetics on Rubisco-limited photosynthesis suggested improved photosynthetic performance of C3 plants from cool habitats at lower temperatures, and C3 plants from warm habitats at higher temperatures, especially at higher CO2 concentration. Thus, variation in Rubisco kinetics for different groups of photosynthetic organisms might need consideration to improve prediction of photosynthesis in future climates. Comparisons between in vitro and in vivo data revealed common trends, but also highlighted a large variability among both types of Rubisco kinetics currently used to simulate photosynthesis, emphasizing the need for more experimental work to fill in the gaps in Rubisco datasets and improve scaling from enzyme kinetics to realized

  20. Photosynthetic traits of five neotropical rainforest tree species: interactions between light response curves and leaf-to-air vapour pressure deficit

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    Marcelo Schramm Mielke

    2005-09-01

    Full Text Available Measurements of leaf gas exchange at different photosynthetic photon flux density (PPFD levels were conducted in order to compare the photosynthetic traits of five neotropical rainforest tree species, with a special emphasis on empirical mathematical models to estimate the light response curve parameters incorporating the effects of leaf-to-air vapour pressure deficit (D on the saturated photosynthetic rate (Amax. All empirical mathematical models seemed to provide a good estimation of the light response parameters. Comparisons of the leaf photosynthetic traits between different species needed to select an appropriate model and indicated the microenvironmental conditions when the data were collected. When the vapour pressure deficit inside the chamber was not controlled, the incorporation of linear or exponencial functions that explained the effects of D on leaf gas exchange, was a very good method to enhance the performance of the models.Medições das trocas gasosas foliares em diferentes níveis do densidade de fluxo de fótons fotossintéticamente ativos (PPFD foram realizadas com o objetivo de comparar as características fotossintéticas de cinco espécies arbóreas de florestas úmidas neotropicais, com especial ênfase em modelos matemáticos empíricos para estimativa de parâmetros derivados das curvas de resposta à radiação luminosa e dos efeitos da diferença de pressão de vapor entre a folha e o ar (D na taxa fotossintética em saturação luminosa (Amax. Os modelos analisados proporcionaram boas estimativas para os parâmetros derivados das curvas de resposta à radiação luminosa. Comparações entre as características fotossintéticas de diferentes espécies devem sempre considerar os modelos utilizados, seguidas de indicações pormenorizadas das condições microambientais no momento em que os dados foram coletados. Quando a diferença de pressão de vapor não for controlada artificialmente durante as medições, a

  1. Leaf traits and photosynthetic responses of Betula pendula saplings to a range of ground-level ozone concentrations at a range of nitrogen loads.

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    Harmens, Harry; Hayes, Felicity; Sharps, Katrina; Mills, Gina; Calatayud, Vicent

    2017-04-01

    Ground-level ozone (O3) concentrations and atmospheric nitrogen (N) deposition rates have increased strongly since the 1950s. Rising ground-level O3 concentrations and atmospheric N deposition both affect plant physiology and growth, however, impacts have often been studied in isolation rather than in combination. In addition, studies are often limited to a control treatment and one or two elevated levels of ozone and/or nitrogen supply. In the current study, three-year old Betula pendula saplings were exposed to seven different O3 profiles (24h mean O3 concentration of 36-68ppb in 2013, with peaks up to an average of 105ppb) in precision-controlled hemispherical glasshouses (solardomes) and four different N loads (10, 30, 50 or 70kgNha(-1)y(-1)) in 2012 and 2013. Here we report on the effects of enhanced O3 concentrations and N load on leaf traits and gas exchange in leaves of varying age and developmental stage in 2013. The response of leaf traits to O3 (but not N) vary with leaf developmental stage. For example, elevated O3 did not affect the chlorophyll content of the youngest fully expanded leaf, but it reduced the chlorophyll content and photosynthetic parameters in aging leaves, relatively more so later than earlier in the growing season. Elevated O3 enhanced the N content of senesced leaves prior to leaf fall, potentially affecting subsequent N cycling in the soil. Enhanced N generally stimulated the chlorophyll content and photosynthetic capacity. Whilst elevated O3 reduced the light-saturated rate of photosynthesis (Asat) in aging leaves, it did not affect stomatal conductance (gs). This suggests that photosynthesis and gs are not closely coupled at elevated O3 under-light saturating conditions. We did not observe any interactions between O3 and N regarding photosynthetic parameters (Vc,max, Jmax, Asat), chlorophyll content, gs, N content in senesced leaves and leaf number. Hence, the sensitivity of these leaf traits to O3 in young silver birch trees is

  2. Photosynthetic traits of Sphagnum and feather moss species in undrained, drained and rewetted boreal spruce swamp forests.

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    Kangas, Laura; Maanavilja, Liisa; Hájek, Tomáš; Juurola, Eija; Chimner, Rodney A; Mehtätalo, Lauri; Tuittila, Eeva-Stiina

    2014-02-01

    In restored peatlands, recovery of carbon assimilation by peat-forming plants is a prerequisite for the recovery of ecosystem functioning. Restoration by rewetting may affect moss photosynthesis and respiration directly and/or through species successional turnover. To quantify the importance of the direct effects and the effects mediated by species change in boreal spruce swamp forests, we used a dual approach: (i) we measured successional changes in moss communities at 36 sites (nine undrained, nine drained, 18 rewetted) and (ii) photosynthetic properties of the dominant Sphagnum and feather mosses at nine of these sites (three undrained, three drained, three rewetted). Drainage and rewetting affected moss carbon assimilation mainly through species successional turnover. The species differed along a light-adaptation gradient, which separated shade-adapted feather mosses from Sphagnum mosses and Sphagnum girgensohnii from other Sphagna, and a productivity and moisture gradient, which separated Sphagnum riparium and Sphagnum girgensohnii from the less productive S. angustifolium, S. magellanicum and S. russowii. Undrained and drained sites harbored conservative, low-production species: hummock-Sphagna and feather mosses, respectively. Ditch creation and rewetting produced niches for species with opportunistic strategies and high carbon assimilation. The direct effects also caused higher photosynthetic productivity in ditches and in rewetted sites than in undrained and drained main sites.

  3. The Impact of Alternative Trait-Scaling Hypotheses for the Maximum Photosynthetic Carboxylation Rate (V (sub cmax)) on Global Gross Primary Production

    Science.gov (United States)

    Walker, Anthony P.; Quaife, Tristan; Van Bodegom, Peter M.; De Kauwe, Martin G.; Keenan, Trevor F.; Joiner, Joanna; Lomas, Mark R.; MacBean, Natasha; Xu, Chongang; Yang, Xiaojuan; hide

    2017-01-01

    The maximum photosynthetic carboxylation rate (V (sub cmax)) is an influential plant trait that has multiple scaling hypotheses, which is a source of uncertainty in predictive understanding of global gross primary production (GPP). Four trait-scaling hypotheses (plant functional type, nutrient limitation, environmental filtering, and plant plasticity) with nine specific implementations were used to predict global V(sub cmax) distributions and their impact on global GPP in the Sheffield Dynamic Global Vegetation Model (SDGVM). Global GPP varied from 108.1 to 128.2 petagrams of Carbon (PgC) per year, 65 percent of the range of a recent model intercomparison of global GPP. The variation in GPP propagated through to a 27percent coefficient of variation in net biome productivity (NBP). All hypotheses produced global GPP that was highly correlated (r equals 0.85-0.91) with three proxies of global GPP. Plant functional type-based nutrient limitation, underpinned by a core SDGVM hypothesis that plant nitrogen (N) status is inversely related to increasing costs of N acquisition with increasing soil carbon, adequately reproduced global GPP distributions. Further improvement could be achieved with accurate representation of water sensitivity and agriculture in SDGVM. Mismatch between environmental filtering (the most data-driven hypothesis) and GPP suggested that greater effort is needed understand V(sub cmax) variation in the field, particularly in northern latitudes.

  4. Evidence for both innate and acquired mechanisms of protection from Plasmodium falciparum in children with sickle cell trait

    Science.gov (United States)

    Gong, Lauren; Maiteki-Sebuguzi, Catherine; Rosenthal, Philip J.; Hubbard, Alan E.; Drakeley, Chris J.; Dorsey, Grant

    2012-01-01

    Sickle cell trait (HbAS) is known to be protective against Plasmodium falciparum malaria, but it is unclear when during the course of infection this protection occurs and whether protection is innate or acquired. To address these questions, a cohort of 601 children 1-10 years of age were enrolled in Kampala, Uganda, and followed for 18 months for symptomatic malaria and asymptomatic parasitemia. Genotyping was used to detect and follow individual parasite clones longitudinally within subjects. Children with HbAS were protected against the establishment of parasitemia, as assessed by the molecular force of infection at older but not younger ages (at 2 years of age: incidence rate ratio [IRR] = 1.16; 95% confidence interval [95% CI], 0.62-2.19; P = .6; at 9 years of age: IRR = 0.50; 95% CI, 0.28-0.87; P = .01), suggesting an acquired mechanism of protection. Once parasitemic, children with HbAS were less likely to progress to symptomatic malaria, with protection again being the most pronounced at older ages (at 2 years of age: relative risk [RR] = 0.92; 95% CI, 0.77-1.10; P = .3; at 9 years of age: RR = 0.68; 95% CI, 0.51-0.91; P = .008). Conversely, the youngest children were best protected against high parasite density (at 2 years of age: relative density = 0.24; 95% CI, 0.10-0.54; P = .001; at 9 years of age: relative density = 0.59; 95% CI, 0.30-1.19; P = .14), suggesting an innate mechanism of protection against this end point. PMID:22327223

  5. Functional traits and structural controls on the relationship between photosynthetic CO2 uptake and sun-induced fluorescence in a Mediterranean grassland under different nutrient availability

    Science.gov (United States)

    Migliavacca, Mirco

    2016-04-01

    Recent studies have shown how human induced nitrogen (N) and phosphorous (P) imbalances affect essential ecosystem processes, and might be particularly important in water-limited ecosystems. Hyperspectral information can be used to directly infer nutrient-induced variation in structural and functional changes of vegetation under different nutrient availability. However, several uncertainties still hamper the direct link between photosynthetic CO2 uptake (gross primary productivity, GPP) and hyperspectral reflectance. Sun-induced fluorescence (SIF) provides a new non-invasive measurement approach that has the potential to quantify dynamic changes in light use efficiency and photosynthetic CO2 uptake. In this contribution we will present an experiment conducted in a Mediterranean grassland, where 16 plots of 8x8 meters were manipulated by adding nutrient (N, P, and NP). Almost simultaneous estimates of canopy scale GPP and SIF were conducted with transparent transient-state canopy chambers and high resolution spectrometers, respectively. We investigated the response of GPP and SIF to different nutrient availability and plant stoichiometry. The second objective was to identify how structural (LAI, leaf angle distribution, and biodiversity) and canopy biochemical properties (e.g. N and chlorophyll content - Chl) control the functional relationship between GPP and SIF. To test the different hypotheses the SCOPE radiative transfer model was used. We ran a factorial experiment with SCOPE to disentangle the main drivers (structure vs biochemistry) of the relationship GPP-SIF. The results showed significant differences in GPP values between N and without N addition plots. We also found that vegetation indices sensitive to pigment variations and physiology (such as photochemical reflectance index PRI) and SIF showed differences between different treatments. SCOPE showed very good agreement with the observed data (R2=0.71). The observed variability in SIF was mainly related

  6. Photosynthetic responses to leaf surface wetness in tropical plant species of Costa Rica with varying leaf traits

    Science.gov (United States)

    Aparecido, L. M. T.; Moore, G. W.; Miller, G. R.; Cahill, A. T.

    2015-12-01

    Wet tropical forests are some of the environments with the greatest annual precipitation, but are also considered as the world's major carbon sink; however, literature postulates that phothsynthesis rates are inhibited while leaves are wet. Yet measurements of photosynthesis during wet conditions are challenging to obtain due to equipment limitations and the extreme complexity of canopy-atmosphere interactions in tropical environments. The objective of this study was to evaluate tropical species reactions to simulated leaf wetness and test the hypothesis that leaf wetness reduces rates of photosynthesis. In a central Costa Rica site with an average 4200 mm annual rainfall, we selected six tropical species with distinct leaf traits in which five sun-exposed leaf replicates from each species were subjected to gas exchange measurements using a LI-6400 IRGA (LICOR Inc., Lincoln, NE) under dry and wet/misted leaf conditions. Relationships between photosynthesis (As) and stomatal conductance (gs) with leaf to air temperature difference (DT), VPD, and relative humidity were evaluated using linear regression analysis. We found that the responses varied greatly among species, but all plants maintained a baseline of activity under wet leaf conditions, suggesting that abaxial leaf As was a significant percentage of total leaf As. Stachytarpheta jamaicens had an 18.7% reduction in As, while others, like Zamia skinneri, had a 7% increase in As. Tibouchina heteromalla showed a rapid stomatal recovery of 2 mins, while Carapa guianensis was slower with 7 mins. This variability between species suggests that leaf traits, such as presence or absence of trichomes, water repellency, vein distribution and size and leaf angle variation, may be critical for optimizing photosynthesis under wet conditions. Relative humidity and leaf temperature were the strongest secondary influences on As and gs under wet leaf conditions. While tropical vegetation-atmosphere interactions are complex, such

  7. Photosynthetic Genes and Genes Associated with the C4 Trait in Maize Are Characterized by a Unique Class of Highly Regulated Histone Acetylation Peaks on Upstream Promoters.

    Science.gov (United States)

    Perduns, Renke; Horst-Niessen, Ina; Peterhansel, Christoph

    2015-08-01

    Histone modifications contribute to gene regulation in eukaryotes. We analyzed genome-wide histone H3 Lysine (Lys) 4 trimethylation and histone H3 Lys 9 acetylation (two modifications typically associated with active genes) in meristematic cells at the base and expanded cells in the blade of the maize (Zea mays) leaf. These data were compared with transcript levels of associated genes. For individual genes, regulations (fold changes) of histone modifications and transcript levels were much better correlated than absolute intensities. When focusing on regulated histone modification sites, we identified highly regulated secondary H3 Lys 9 acetylation peaks on upstream promoters (regulated secondary upstream peaks [R-SUPs]) on 10% of all genes. R-SUPs were more often found on genes that were up-regulated toward the blade than on down-regulated genes and specifically, photosynthetic genes. Among those genes, we identified six genes encoding enzymes of the C4 cycle and a significant enrichment of genes associated with the C4 trait derived from transcriptomic studies. On the DNA level, R-SUPs are frequently associated with ethylene-responsive elements. Based on these data, we suggest coevolution of epigenetic promoter elements during the establishment of C4 photosynthesis.

  8. Correlation and quantitative trait loci analyses of total chlorophyll content and photosynthetic rate of rice (Oryza sativa) under water stress and well-watered conditions.

    Science.gov (United States)

    Hu, Song-Ping; Zhou, Ying; Zhang, Lin; Zhu, Xiu-Dong; Li, Lin; Luo, Li-Jun; Liu, Guo-Lan; Zhou, Qing-Ming

    2009-09-01

    In order to explore the relevant molecular genetic mechanisms of photosynthetic rate (PR) and chlorophyll content (CC) in rice (Oryza sativa L.), we conducted a series of related experiments using a population of recombinant inbred lines (Zhenshan97B x IRAT109). We found a significant correlation between CC and PR (R= 0.19**) in well-watered conditions, but no significant correlation during water stress (r= 0.08). We detected 13 main quantitative trait loci (QTLs) located on chromosomes 1, 2, 3, 4, 5, 6, and 10, which were associated with CC, including six QTLs located on chromosomes 1, 2, 3, 4, and 5 during water stress, and seven QTLs located on chromosomes 2, 3, 4, 6, and 10 in well-watered conditions. These QTLs explained 47.39% of phenotypic variation during water stress and 56.19% in well-watered conditions. We detected four main QTLs associated with PR; three of them (qPR2, qPR10, qPR11) were located on chromosomes 2, 10, and 11 during water stress, and one (qPR10) was located on chromosome 10 in well-watered conditions. These QTLs explained 34.37% and 18.41% of the phenotypic variation in water stress and well-watered conditions, respectively. In total, CC was largely controlled by main QTLs, and PR was mainly controlled by epistatic QTL pairs.

  9. Mammalian-specific genomic functions: Newly acquired traits generated by genomic imprinting and LTR retrotransposon-derived genes in mammals

    Science.gov (United States)

    KANEKO-ISHINO, Tomoko; ISHINO, Fumitoshi

    2015-01-01

    Mammals, including human beings, have evolved a unique viviparous reproductive system and a highly developed central nervous system. How did these unique characteristics emerge in mammalian evolution, and what kinds of changes did occur in the mammalian genomes as evolution proceeded? A key conceptual term in approaching these issues is “mammalian-specific genomic functions”, a concept covering both mammalian-specific epigenetics and genetics. Genomic imprinting and LTR retrotransposon-derived genes are reviewed as the representative, mammalian-specific genomic functions that are essential not only for the current mammalian developmental system, but also mammalian evolution itself. First, the essential roles of genomic imprinting in mammalian development, especially related to viviparous reproduction via placental function, as well as the emergence of genomic imprinting in mammalian evolution, are discussed. Second, we introduce the novel concept of “mammalian-specific traits generated by mammalian-specific genes from LTR retrotransposons”, based on the finding that LTR retrotransposons served as a critical driving force in the mammalian evolution via generating mammalian-specific genes. PMID:26666304

  10. 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.

  11. Effect of Soil texture on Photosynthetic traits and the deposition of Dry matter accumulation of peanut%土壤质地对花生光合特性及干物质积累分配的影响

    Institute of Scientific and Technical Information of China (English)

    贾立华; 王月福; 陈安余; 冯锴

    2013-01-01

    The paper explored the effect of soil texture on photosynthetic traits and detribution of dry matter accumulation of peanut,in order to explicit the suitable soil texture appropriated for high-yielding peanut cultivation.The soil texture including Sandy soil,Clay and Loam,and the experiment were implemented in box plant method.The results showed that the early period of peanut growth and development is Sandy soil>Loam>Clay and the later period is Loam>Sandy soil>Clay on Leaf area per plant,Functional leaf chlorophyll content,Net photosynthetic rate and Distribution of dry matter accumulation of peanut.Sandy soil is in favor of early period of photosynthetic matter accumulation,Loam is in favor of whole period,and Clay is not conductive to the whole period.Loam is more suitable than Clay and Sandy soil on distribution ratio of peanut organ dry matter accumulation.Loam has a higher pod yield than Sandy soil and Clay.%为了明确适合花生生长获得高产的土壤类型,采用箱栽的方法,研究了不同质地土壤(砂土、壤土、粘土)对花生光合特性及干物质积累分配的影响.结果表明,花生单株叶面积、功能叶叶绿素SPAD值、净光合速率和植株总干物质重在生育前期表现为砂土>壤土>粘土,在生育后期则表现为壤土>砂土>粘土.砂土有利于花生前期光合物质积累,壤土则在整个生育期内均有利于花生光合物质积累,而粘土则在整个生育期内均不利于花生光合物质积累.壤土花生各器官干物质分配比例较粘土和砂土合理.壤土的荚果产量显著高于砂土和粘土.

  12. 长期施肥对水稻光合特性及水分利用效率的影响%Effects of long-term fertilization on rice photosynthetic traits and water use efficiency

    Institute of Scientific and Technical Information of China (English)

    袁颖红; 樊后保; 黄欠如; 廖迎春; 黄荣珍

    2009-01-01

    A field experiment has being conducted for 27 years in Jinxian County, Institute of Red Soil in Jiangxi Province (116°20'24" E, 28°15'30" N) to study the effects of fertilization on the rice photosynthetic traits and water use efficiency. Four treatments were installed,i. e., no fertilization (CK), chemical fertilization (N, NP, NPK), organic fertilization (M), and chemi-cal and organic fertilization (NPKM). Long-term fertilization, especially treatment NPKM, in- creased the flag leaf chlorophyll content, net photosynthetic rate, stomatal conductance, transpi-ration rate, and water use efficiency of rice at its all growth stages and the rice yield, and de-creased the flag leaf intercellular CO_2 concentration. With the growth of rice, the chlorophyll content, net photosynthetic rate, stomatal conductance, and transpiration rate decreased, but the intercellular CO_2 concentration increased. The water use efficiency was the greatest at full-head-ing stage. There were significant positive correlations between the chlorophyll content and net photosynthetic rate at various growth stages and the rice yield, Long-term fertilization, especially the combined chemical and organic fertilization, was favorable to the rice growth and develop-ment, water use efficiency, and yield production in red soil region.%在实施了27年的长期田间定位试验区,研究了长期不同施肥对红壤区水稻光合特性及水分利用效率的影响.结果表明:在不施肥(CK)、无机肥(N、NP、NPK)、有机肥(猪粪+紫云英绿肥,M)和无机肥与有机肥配施(NPKM)处理中,长期施用肥料,特别是有机肥与无机肥配施提高水稻各生育期剑叶叶绿素含量、净光合作用速率、气孔导度、蒸腾速率、水分利用效率和水稻产量,降低水稻剑叶胞间CO_2浓度;水稻剑叶叶绿素含量、净光合作用速率、气孔导度、蒸腾速率随发育阶段演进而减小,孕穗期>齐穗期>乳熟期,而胞间CO_2浓度相反;水分利

  13. Relationship of Leaf Photosynthetic Characteristics and Root Physiological Traits with Grain Yield in Super Rice%超级稻叶片光合特性和根系生理性状与产量的关系

    Institute of Scientific and Technical Information of China (English)

    付景; 陈露; 黄钻华; 王志琴; 杨建昌

    2012-01-01

    为阐明超级稻产量形成机制,以4个超级稻品种[两优培九和Ⅱ优084(杂交籼稻)、淮稻9号和武粳15(粳稻)]为材料,2个高产品种[汕优63(杂交籼稻)和扬辐粳8号(粳稻)]为对照,观测了不同生育时期叶片光合性状和根系生理性状的变化特点.结果表明,4个超级稻品种的平均总颖花量和产量较两个对照品种分别高出43.5%和16.1%,但超级稻的结实率较对照品种低15.3个百分点.超级稻品种在生育前期叶片中叶绿素a含量、叶绿素b含量、总叶绿索含量、类胡萝卜素含量、光合速率、蒸腾速率、气孔导度和根系中单位干重根系活力、每株根系活力、总根系吸收面积、活跃吸收面积和比表面积均高于对照品种,而在生育后期以上性状指标下降速率大于各自对照品种,直至齐穗后20 d前以上性状指标均小于各自对照品种.说明超级稻强大的产量库容与其生育前中期较强的叶片光合能力和较好的根系生理性状密切相关,生育后期叶片光合能力和根系生理活性下降快导致其结实率下降,从而限制了其产量潜力的发挥.提高生育后期特别是结实后期根系生理活性是进一步提高超级稻产量的重要途径.%The success in super rice breeding has been considered as a great progress in rice production in China. This study aimed to understand the mechanism underlying the yield formation of super rice. Four super rice cultivars, Liangyoupeijiu and Ilyou 084 (indica hybrids), Huaidao 9 and Wujing 15 (japonica), and two elite check cultivars, Shanyou 63 (Mica hybrids) and Yangfujing 8 (japonica), were grown in field. Leaf photosynthetic characteristics and root physiological traits were investigated at different growth stages. The results showed that average total spilcelet number and grain yield of the four super rice cultivars were 43.5% and 16.1%, respectively, more than those of two elite check cultivars, but the seed

  14. Effects of long-term nitrogen addition on photosynthetic characteristics and leaf traits of Stipa baicalensis in Inner Mongolia,China%贝加尔针茅光合特征与叶片功能特性对长期氮添加的响应

    Institute of Scientific and Technical Information of China (English)

    刘红梅; 李洁; 皇甫超河; 陈新微; 杨殿林

    2016-01-01

    以贝加尔针茅草甸草原建群种贝加尔针茅为研究对象,通过一个连续6年氮添加野外控制试验,设置5个氮素处理:N0(0 kg N/hm2)、N30(30 kg N/hm2)、N50(50 kg N/hm2)、N100(100 kg N/hm2)、N150(150 kg N/hm2),探讨氮沉降变化对贝加尔针茅种群光合特性与叶片功能特性变化规律及其影响因子。结果表明,氮素添加变化显著影响贝加尔针茅的净光合速率等光合特性,氮素添加处理净光合速率(net photosynthetic rate,Pn )、气孔导度(stomatal conductance,Gs )、蒸腾速率(transpiration rate,Tr )、光合氮利用效率(photosynthetic nitrogen use effi-ciency,PNUE)和光合能量利用效率(photosynthetic energy use efficiency,PEUE)均低于或显著低于无氮素添加处理。氮素添加处理叶片比叶面积(specific leaf area,SLA)、叶片 N 含量(leaf N content,N mass )、建成成本(leaf construction cost,CC mass )、叶片 N∶P 均高于或显著高于无氮素添加处理。相关分析表明,5个氮素处理的 Pn 与Gs 、Tr 、PNUE、PEUE、叶片 P 含量(leaf P content,P mass )、土壤 N ∶P 呈显著正相关,与叶片比叶面积(SLA)、N mass 、CC mass 、土壤含水量、土壤 pH 值呈极显著负相关;叶片 N mass 与 SLA、CC mass 、土壤 N∶P 呈显著正相关,与PNUE、PEUE、P mass 、土壤含水量、土壤 pH 值呈显著负相关。综合以上研究表明,长期氮添加会降低贝加尔针茅净光合速率、养分利用效率,提高叶片建成成本和叶片 N∶P,土壤含水量和土壤 pH 值是引起这种改变发生的主要因子。%Atmospheric nitrogen deposition is an important component phenomenon of global change,and in-duces a series of ecological problems.We conducted a field manipulation experiment to study the photosynthet-ic response and change in leaf functional traits after long-term nitrogen addition in

  15. 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.

  16. Acquired blepharoptosis

    NARCIS (Netherlands)

    Oosterhuis, HJGH

    1996-01-01

    A review is given of the aetiology and possible treatment of acquired (non-congenital) blepharoptosis, which is a common but not specific sign of neurological disease: The diagnostic categories of upper eyelid drooping are scheduled as (a) pseudo-ptosis due to a local process or overactivity of eye

  17. Acquired blepharoptosis

    NARCIS (Netherlands)

    Oosterhuis, HJGH

    1996-01-01

    A review is given of the aetiology and possible treatment of acquired (non-congenital) blepharoptosis, which is a common but not specific sign of neurological disease: The diagnostic categories of upper eyelid drooping are scheduled as (a) pseudo-ptosis due to a local process or overactivity of eye

  18. Photosynthetic Diurnal Variation of Soybean Cultivars with High Photosynthetic Efficiency

    Institute of Scientific and Technical Information of China (English)

    MAN Wei-qun; DU Wei-guang; ZHANG Gui-ru; LUAN Xiao-yan; GE Qiao-ying; HAO Nai-bin; CHEN Yi

    2002-01-01

    The photosynthetic characters were investigated among soybean cultivars with high photosynthetic efficiency and high yield. The results indicated that: 1) There were significant differences in photosynthetic rate (Ph) and dark respiration rate (DR) under saturation light intensity and appropriate temperature.2) There were a little difference in light compensation point among them. Photo flux density (PFD) were mong the cultivars. Diurnal variation of Pn was shown a curve with two peaks. 4) The cultivars with high photosynthetic efficiency were subjected less to photoinhibition than that with high yield. Critical temperatures of photoinhibition in high photosynthetic efficiency cultivars were higher than that of high yield.

  19. Acquired Methemoglobinaemia

    Directory of Open Access Journals (Sweden)

    Adil Al-Lawati

    2012-05-01

    Full Text Available Acquired methemoglobinaemia is a relatively rare condition and, therefore infrequently encountered in acute medical practice. Suspicion of the condition may be triggered when the measured PaO2 is ‘out of keeping’ with the oxygen saturations that are discovered with pulse oximetry. We describe two separate cases of acquired methemoglobinaemia secondary to the recreational use of alkyl nitrites (’poppers’. The patients presented at separate times to two different teaching hospitals in London, UK. The similarity of these cases has led the authors to conclude that a raised awareness of this potentially fatal condition, and its association with a widely-available recreational drug, is necessary to ensure a correct and timely diagnosis.

  20. Hydraulic basis for the evolution of photosynthetic productivity.

    Science.gov (United States)

    Scoffoni, Christine; Chatelet, David S; Pasquet-Kok, Jessica; Rawls, Michael; Donoghue, Michael J; Edwards, Erika J; Sack, Lawren

    2016-05-27

    Clarifying the evolution and mechanisms for photosynthetic productivity is a key to both improving crops and understanding plant evolution and habitat distributions. Current theory recognizes a role for the hydraulics of water transport as a potential determinant of photosynthetic productivity based on comparative data across disparate species. However, there has never been rigorous support for the maintenance of this relationship during an evolutionary radiation. We tested this theory for 30 species of Viburnum, diverse in leaf shape and photosynthetic anatomy, grown in a common garden. We found strong support for a fundamental requirement for leaf hydraulic capacity (Kleaf) in determining photosynthetic capacity (Amax), as these traits diversified across this lineage in tight coordination, with their proportionality modulated by the climate experienced in the species' range. Variation in Kleaf arose from differences in venation architecture that influenced xylem and especially outside-xylem flow pathways. These findings substantiate an evolutionary basis for the coordination of hydraulic and photosynthetic physiology across species, and their co-dependence on climate, establishing a fundamental role for water transport in the evolution of the photosynthetic rate.

  1. Acquired Techniques

    DEFF Research Database (Denmark)

    Lunde Nielsen, Espen; Halse, Karianne

    2013-01-01

    Acquired Techniques - a Leap into the Archive, at Aarhus School of Architecture. In collaboration with Karianne Halse, James Martin and Mika K. Friis. Following the footsteps of past travelers this is a journey into tools and techniques of the architectural process. The workshop will focus upon...... architectural production as a conglomerate of various analogue and digital methods, and provide the basics, the tips/tricks - and how the tool themselves becomes operational for spatial/thematic investigations. Eventually, this will become a city, exhibition and phamplet inhabited by the (by...

  2. Photosynthetic Pigments in Diatoms

    OpenAIRE

    Paulina Kuczynska; Malgorzata Jemiola-Rzeminska; Kazimierz Strzalka

    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...

  3. Differential allocation to photosynthetic and non-photosynthetic nitrogen fractions among native and invasive species.

    Science.gov (United States)

    Funk, Jennifer L; Glenwinkel, Lori A; Sack, Lawren

    2013-01-01

    Invasive species are expected to cluster on the "high-return" end of the leaf economic spectrum, displaying leaf traits consistent with higher carbon assimilation relative to native species. Intra-leaf nitrogen (N) allocation should support these physiological differences; however, N biochemistry has not been examined in more than a few invasive species. We measured 34 leaf traits including seven leaf N pools for five native and five invasive species from Hawaii under low irradiance to mimic the forest understory environment. We found several trait differences between native and invasive species. In particular, invasive species showed preferential N allocation to metabolism (amino acids) rather than photosynthetic light reactions (membrane-bound protein) by comparison with native species. The soluble protein concentration did not vary between groups. Under these low irradiance conditions, native species had higher light-saturated photosynthetic rates, possibly as a consequence of a greater investment in membrane-bound protein. Invasive species may succeed by employing a wide range of N allocation mechanisms, including higher amino acid production for fast growth under high irradiance or storage of N in leaves as soluble protein or amino acids.

  4. Differential allocation to photosynthetic and non-photosynthetic nitrogen fractions among native and invasive species.

    Directory of Open Access Journals (Sweden)

    Jennifer L Funk

    Full Text Available Invasive species are expected to cluster on the "high-return" end of the leaf economic spectrum, displaying leaf traits consistent with higher carbon assimilation relative to native species. Intra-leaf nitrogen (N allocation should support these physiological differences; however, N biochemistry has not been examined in more than a few invasive species. We measured 34 leaf traits including seven leaf N pools for five native and five invasive species from Hawaii under low irradiance to mimic the forest understory environment. We found several trait differences between native and invasive species. In particular, invasive species showed preferential N allocation to metabolism (amino acids rather than photosynthetic light reactions (membrane-bound protein by comparison with native species. The soluble protein concentration did not vary between groups. Under these low irradiance conditions, native species had higher light-saturated photosynthetic rates, possibly as a consequence of a greater investment in membrane-bound protein. Invasive species may succeed by employing a wide range of N allocation mechanisms, including higher amino acid production for fast growth under high irradiance or storage of N in leaves as soluble protein or amino acids.

  5. 密度和空间布局种植方式对夏玉米穗位叶光合生理性状的影响%Effects of Planting Densities and Row Spacing Modes on Photosynthetic and Physiological Traits of Ear Leaves of Summer Maize

    Institute of Scientific and Technical Information of China (English)

    王萌; 陈国强; 金海燕; 韩晨光; 臧凤艳; 李子芳; 王金龙; 吴锡冬

    2016-01-01

    effects on net photosynthetic rate and its rela-tive traits of a summer maize variety ZD958 at different growth stages(flowering stage,silking stage,earlier filling stage,later filling stage and full ripe stage).The results indicated that the row spacing mode of three plants per spot with wide and narrow row could significantly decrease net photosynthetic rate of ear leaves at flowering stage and full ripe stage.At the planting density of 81 000 plants /ha,the net photosynthetic rate was not associated with row spac-ing modes.Meanwhile,under the row spacing mode of one plant per spot with equal row,planting density did not significantly affect net photosynthetic rate of ear leaves.It was noteworthy that the carotenoid content was closely as-sociated with planting densities,row spacing modes and their interaction effects.Under the row spacing mode of three plants per spot with equal row,the planting density of 93 000 plants /ha significantly decreased carotenoid con-tent at the first three growth stages,while both the densities of 69 000 under the mode of three plants per spot with wide and narrow row and 57 000 plants /ha under the mode of one plant per spot with equal row could significantly reduce carotenoid content at the full ripe stage.It was also found that the maximum photochemical efficiency of PSⅡ was not influenced by planting densities,row spacing modes and their interaction effects.In general,the plant-ing density of 81 000 plants /ha was not closely associated with row spacing modes,which was similar with the rela-tionships between the row spacing mode of one plant per spot with equal row and planting densities.In these two cir-cumstances,the net photosynthetic rate and its relative traits could maintain relatively higher levels.Our results could also supply experimental evidences for explaining the relationships among cropping patterns,photosynthetic products source and yield pool based on photosynthetic matters and water physiology(pigment content

  6. 胺鲜酯和镉对蓖麻幼苗光合生理特性的影响%RESPONSES OF PHOTOSYNTHETIC TRAITS OF CASTOR BEAN SEEDLINGS TO CADMIUM AND DIETHYL AMINOETHYL HEXANOATE

    Institute of Scientific and Technical Information of China (English)

    张铮; 钱宝云; 程晓庆; 刘彩凤; 史刚荣

    2011-01-01

    To determine whether diethyl aminoethyl hexanoate ( DA-6 ) pretreatment alleviated the cadmium ( Cd) toxicity to castor bean ( Ricinus communis L. ) seedlings, tffects of Cd (0, 50μmol · L-1 CdCl2 ) and DA-6 (0 , 0. 1, 10 and lOOOmg · L-1 ) , and their interactions on plant growth and photosynthesis were investigated. Results showed that 50 ixmol · L-1 CdCl2 inhibited plant growth and photosynthesis of castor seedlings. Under Cd exposure, the net photosynthetic rate (Pn) , stomatal conductance (Gs) and transpiration rate (E) , photosynthetic pigment contents (Chi a, Chi b, Chi a + b, Car and Chi /Car) and chlorophyll fluorescence parameters (Fm, Fv/Fm, Fv/Foand ⅡPS Ⅱ) decreased, whereas the intercellular CO2 concentration (Ci) , Chi a/b and Fo increased. Presoaking seeds with different concentrations of DA-6 did not change the plant growth regardless of Cd. In the absence of Cd, DA-6 pretreatment significantly enhanced the pigment contents (Chi a, Chi b, Chi a + b and Car) in castor leaves, while the ratio of pigment content ( Chi a/b, Chi/Car) , chlorophyll fluorescence parameters, and gas exchange parameters remained unaffected. In the present of Cd, presoaking seeds with 10 and lOOOmg · L-1 DA-6 caused a reduction in pigment contents (Chi a, Chi b, Chi a + b and Car) , gas exchange parameters (Pn, E and Gs) , as well as chlorophyllfluorescence parameters (Fm, Fv/Fm, Fv/Foand ΦPS Ⅱ) in castor seedlings. It was indicated that DA-6 presoaking might aggravate, rather than alleviate, the inhibition of Cd on photosynthesis of castor bean seedlings.%以蓖麻(Ricinus communis L.)为研究对象,通过水培试验研究胺鲜酯(DA-6)和镉(Cd)对蓖麻生长和光合生理特性的交互作用,探讨DA-6浸种对植物Cd毒害是否具有缓解作用.研究结果表明,50μmol·L-1CdCl2对蓖麻幼苗生长和光合作用具有抑制作用.Cd处理显著降低蓖麻叶片的光合速率(Pn)、气孔导度(Gs)和蒸腾速率(E),而胞间CO2浓度(Ci)则明

  7. 氮磷水平对龙须菜生长和光合特性的影响%EFFECTS OF NITROGEN AND PHOSPHOROUS LEVELS ON GROWTH AND PHOTOSYNTHETIC TRAITS OF GRACILARIA LEMANEIFORMIS (RHODO-PHYTA)

    Institute of Scientific and Technical Information of China (English)

    李枫; 邹定辉; 刘兆普; 赵耕毛; 程丽巍; 朱喜锋; 陈伟洲

    2009-01-01

    Aim Our objective was to investigate the impacts of different nutrient levels on the physiology of Gracilaria lemaneiformis to evaluate the relationship between this mariculture species and costal environment.Methods Thalli of Gracilaria lemaneiformis were cultured for 15 days under four different nutrient conditions (low N and low P, low N and high P, high N and low P, and high N and high P) to examine the possible effects of the availability of different nutrients on growth and photosynthesis in this alga. Important findings Growth of G. lemaneiformis was enhanced with the low N and high P treatment, high N and low P treatment, and high N and high P treatment, compared to low N and low P treatment. The highest relative growth rate (RGR) and biomass were observed under high N and high P treatment. Gracilaria lemaneiformis was capable of using HCO_3~- as a source of exogenous inorganic carbon (Ci) for its photosynthesis, and the ability was increased at the above three nutrient conditions. Both carbon-saturated photosynthetic rate and apparent half saturation constant under high N and high P treatment were significant higher than those under low N and low P treatment by 118% and 48.71%, respectively. Photochemical efficiency of G. lemaneiformis was stimulated with low N and high P treatment, but was inhibited at the two high N treatments. Thus, the rates of growth and photosynthesis were the highest, but the photochemical efficiency was the lowest in G. lemaneiformis grown under high N and high P treatment.%研究不同营养盐条件对龙须菜(Gracilaria lemaneiformis)的生理效应,对深入了解龙须菜与近海环境的相互作用具有重要意义.在低氮低磷(LNLP)、低氮高磷(LNHP)、高氮低磷(HNLP)和高氮高磷(HNaP)4种营养盐条件下培养龙须菜15 d,以探讨不同氮、磷水平对龙须菜生长和光合特性的影响.结果表明:1)LNHP、HNLP和HNHP处理促进了龙须菜的生长,其中HNHP处理下龙须菜具有最大的

  8. 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

  9. The Photosynthetic Cycle

    Science.gov (United States)

    Calvin, Melvin

    1955-03-21

    A cyclic sequence of transformations, including the carboxylation of RuDP (ribulose diphosphate) and its re-formation, has been deduced as the route for the creation of reduced carbon compounds in photosynthetic organisms. With the demonstration of RuDP as substrate for the carboxylation in a cell-free system, each of the reactions has now been carried out independently in vitro. Further purification of this last enzyme system has confirmed the deduction that the carboxylation of RuDP leads directly to the two molecules of PGA (phosphoglyceric acid) involving an internal dismutation and suggesting the name "carboxydismutase" for the enzyme. As a consequence of this knowledge of each of the steps in the photosynthetic CO{sub 2} reduction cycle, it is possible to define the reagent requirements to maintain it. The net requirement for the reduction of one molecule of CO{sub 2} is four equivalents of [H]and three molecules of ATP (adenine triphosphate). These must ultimately be supplied by the photochemical reaction. Some possible ways in which this may be accomplished are discussed.

  10. 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.

  11. Enhancement of leaf photosynthetic capacity through increased stomatal density in Arabidopsis.

    Science.gov (United States)

    Tanaka, Yu; Sugano, Shigeo S; Shimada, Tomoo; Hara-Nishimura, Ikuko

    2013-05-01

    Photosynthetic rate is determined by CO2 fixation and CO2 entry into the plant through pores in the leaf epidermis called stomata. However, the effect of increased stomatal density on photosynthetic rate remains unclear. This work investigated the effect of alteration of stomatal density on leaf photosynthetic capacity in Arabidopsis thaliana. Stomatal density was modulated by overexpressing or silencing STOMAGEN, a positive regulator of stomatal development. Leaf photosynthetic capacity and plant growth were examined in transgenic plants. Increased stomatal density in STOMAGEN-overexpressing plants enhanced the photosynthetic rate by 30% compared to wild-type plants. Transgenic plants showed increased stomatal conductance under ambient CO2 conditions and did not show alterations in the maximum rate of carboxylation, indicating that the enhancement of photosynthetic rate was caused by gas diffusion changes. A leaf photosynthesis-intercellular CO2 concentration response curve showed that photosynthetic rate was increased under high CO2 conditions in association with increased stomatal density. STOMAGEN overexpression did not alter whole plant biomass, whereas its silencing caused biomass reduction. Our results indicate that increased stomatal density enhanced leaf photosynthetic capacity by modulating gas diffusion. Stomatal density may be a target trait for plant engineering to improve photosynthetic capacity.

  12. 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

  13. Light-exposed shoots of seven coexisting deciduous species show common photosynthetic responses to tree height.

    Science.gov (United States)

    Miyata, Rie; Kohyama, Takashi S

    2016-10-01

    Functional traits of light-exposed leaves have been reported to show tree height-dependent change. However, it remains unknown how plastic response of leaf traits to tree height is linked with shoot-level carbon gain. To answer this question, we examined the photosynthetic properties of fully lit current-year shoots in crown tops with various heights for seven deciduous broad-leaved species dominated in a cool-temperate forest in northern Japan. We measured leaf mass, stomatal conductance, nitrogen content, light-saturated net photosynthetic rate (all per leaf lamina area), foliar stable carbon isotope ratio, and shoot mass allocation to leaf laminae. We employed hierarchical Bayesian models to simultaneously quantify inter-trait relationships for all species. We found that leaf and shoot traits were co-varied in association with height, and that there was no quantitative inter-specific difference in leaf- and shoot-level plastic responses to height. Nitrogen content increased and stomatal conductance decreased with height. Reflecting these antagonistic responses to height, photosynthetic rate was almost unchanged with height. Photosynthetic rate divided by stomatal conductance as a proxy of photosynthetic water use efficiency sufficiently explained the variation of foliar carbon isotope ratio. The increase in mass allocation to leaves in a shoot compensated for the height-dependent decline in photosynthetic rate per leaf lamina mass. Consequently, photosynthetic gain at the scale of current-year shoot mass was kept unchanged with tree height. We suggest that the convergent responses of shoot functional traits across species reflect common requirements for trees coexisting in a forest.

  14. Multiscale photosynthetic exciton transfer

    CERN Document Server

    Ringsmuth, A K; Stace, T M; 10.1038/nphys2332

    2012-01-01

    Photosynthetic light harvesting provides a natural blueprint for bioengineered and biomimetic solar energy and light detection technologies. Recent evidence suggests some individual light harvesting protein complexes (LHCs) and LHC subunits efficiently transfer excitons towards chemical reaction centers (RCs) via an interplay between excitonic quantum coherence, resonant protein vibrations, and thermal decoherence. The role of coherence in vivo is unclear however, where excitons are transferred through multi-LHC/RC aggregates over distances typically large compared with intra-LHC scales. Here we assess the possibility of long-range coherent transfer in a simple chromophore network with disordered site and transfer coupling energies. Through renormalization we find that, surprisingly, decoherence is diminished at larger scales, and long-range coherence is facilitated by chromophoric clustering. Conversely, static disorder in the site energies grows with length scale, forcing localization. Our results suggest s...

  15. QTLs analysis of rice peduncle vascular bundle and panicle traits

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@The vascular bundle in plants plays an important role in transportation of photosynthetic products, mineral nutrients, water, and so on. Significant positive correlations were found between grain yield, panicle traits and the No. Of peduncle vascular bundles. So, it is very important to study the inheritance of peduncle vascular bundle, which is a quantitative trait.

  16. Horizontal gene transfer in the evolution of photosynthetic eukaryotes

    Institute of Scientific and Technical Information of China (English)

    Jinling HUANG; Jipei YUE

    2013-01-01

    Horizontal gene transfer (HGT) may not only create genome mosaicism,but also introduce evolutionary novelties to recipient organisms.HGT in plastid genomes,though relatively rare,still exists.HGT-derived genes are particularly common in unicellular photosynthetic eukaryotes and they also occur in multicellular plants.In particular,ancient HGT events occurring during the early evolution of primary photosynthetic eukaryotes were probably frequent.There is clear evidence that anciently acquired genes played an important role in the establishment of primary plastids and in the transition of plants from aquatic to terrestrial environments.Although algal genes have often been used to infer historical plastids in plastid-lacking eukaryotes,reliable approaches are needed to distinguish endosymbionts-derived genes from those independently acquired from preferential feeding or other activities.

  17. Global-scale environmental control of plant photosynthetic capacity.

    Science.gov (United States)

    Ali, Ashehad A; Xu, Chonggang; Rogers, Alistair; McDowell, Nathan G; Medlyn, Belinda E; Fisher, Rosie A; Wullschleger, Stan D; Reich, Peter B; Vrugt, Jasper A; Bauerle, William L; Santiago, Louis S; Wilson, Cathy J

    2015-12-01

    Photosynthetic capacity, determined by light harvesting and carboxylation reactions, is a key plant trait that determines the rate of photosynthesis; however, in Earth System Models (ESMs) at a reference temperature, it is either a fixed value for a given plant functional type or derived from a linear function of leaf nitrogen content. In this study, we conducted a comprehensive analysis that considered correlations of environmental factors with photosynthetic capacity as determined by maximum carboxylation (V(cm)) rate scaled to 25 degrees C (i.e., V(c),25; μmol CO2 x m(-2)x s(-1)) and maximum electron transport rate (J(max)) scaled to 25 degrees C (i.e., J25; μmol electron x m(-2) x s(-1)) at the global scale. Our results showed that the percentage of variation in observed V(c),25 and J25 explained jointly by the environmental factors (i.e., day length, radiation, temperature, and humidity) were 2-2.5 times and 6-9 times of that explained by area-based leaf nitrogen content, respectively. Environmental factors influenced photosynthetic capacity mainly through photosynthetic nitrogen use efficiency, rather than through leaf nitrogen content. The combination of leaf nitrogen content and environmental factors was able to explain -56% and -66% of the variation in V(c),25 and J25 at the global scale, respectively. Our analyses suggest that model projections of plant photosynthetic capacity and hence land-atmosphere exchange under changing climatic conditions could be substantially improved if environmental factors are incorporated into algorithms used to parameterize photosynthetic capacity in ESMs.

  18. Freshwater Biological Traits Database (Traits)

    Science.gov (United States)

    The traits database was compiled for a project on climate change effects on river and stream ecosystems. The traits data, gathered from multiple sources, focused on information published or otherwise well-documented by trustworthy sources.

  19. Acquired platelet function defect

    Science.gov (United States)

    Acquired qualitative platelet disorders; Acquired disorders of platelet function ... blood clotting. Disorders that can cause problems in platelet function include: Idiopathic thrombocytopenic purpura Chronic myelogenous leukemia Multiple ...

  20. Plastic traits of an exotic grass contribute to its abundance but are not always favourable.

    Directory of Open Access Journals (Sweden)

    Jennifer Firn

    Full Text Available In herbaceous ecosystems worldwide, biodiversity has been negatively impacted by changed grazing regimes and nutrient enrichment. Altered disturbance regimes are thought to favour invasive species that have a high phenotypic plasticity, although most studies measure plasticity under controlled conditions in the greenhouse and then assume plasticity is an advantage in the field. Here, we compare trait plasticity between three co-occurring, C(4 perennial grass species, an invader Eragrostis curvula, and natives Eragrostis sororia and Aristida personata to grazing and fertilizer in a three-year field trial. We measured abundances and several leaf traits known to correlate with strategies used by plants to fix carbon and acquire resources, i.e. specific leaf area (SLA, leaf dry matter content (LDMC, leaf nutrient concentrations (N, C:N, P, assimilation rates (Amax and photosynthetic nitrogen use efficiency (PNUE. In the control treatment (grazed only, trait values for SLA, leaf C:N ratios, Amax and PNUE differed significantly between the three grass species. When trait values were compared across treatments, E. curvula showed higher trait plasticity than the native grasses, and this correlated with an increase in abundance across all but the grazed/fertilized treatment. The native grasses showed little trait plasticity in response to the treatments. Aristida personata decreased significantly in the treatments where E. curvula increased, and E. sororia abundance increased possibly due to increased rainfall and not in response to treatments or invader abundance. Overall, we found that plasticity did not favour an increase in abundance of E. curvula under the grazed/fertilized treatment likely because leaf nutrient contents increased and subsequently its' palatability to consumers. E. curvula also displayed a higher resource use efficiency than the native grasses. These findings suggest resource conditions and disturbance regimes can be manipulated to

  1. Frankincense tapping reduced photosynthetic carbon gain in Boswellia papyrifera (Burseraceae) trees

    NARCIS (Netherlands)

    Mengistu, T.; Sterck, F.J.; Anten, N.P.R.; Bongers, F.

    2012-01-01

    Whole-crown carbon gain depends on environmental variables and functional traits, and in turn sets limits to growth sinks of trees. We estimated the annual whole-crown carbon gain of trees of the species Boswellia papyrifera, which are tapped for frankincense, by integrating leaf photosynthetic rate

  2. 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.

  3. Effects of Rht10 on Agronomic and Photosynthetic Traits in ‘Lumai15' and Its Male-sterility Lines%Rht10基因对‘鲁麦15'农艺性状和光合生理特性的影响

    Institute of Scientific and Technical Information of China (English)

    孙正娟; 高庆荣; 王茂婷; 田守波; 袁凯; 于松

    2011-01-01

    利用‘鲁麦15'、‘Rht10鲁麦15'、‘Ms2鲁麦15'及‘Ms2+Rht10鲁麦15'近等基因系为试验材料,研究了Rht10基因对小麦农艺性状、净光合速率(Pn)、蒸腾速率(Tr)等光合生理特性的影响.结果表明,Rht10使小麦的挑旗、抽穗、开花期均推迟了4~5 d;Rht10对‘鲁麦15'和‘Ms2鲁麦15'的降秆强度分别为53.77%和53.00%,穗长显著缩短(P0.05).含有Rht10基因的材料与不含此基因的材料之间的光合生理参数普遍存在显著差异,但在不同时期不同参数差异正负不同;在灌浆后期,Rht10对Pn有显著正效应(P<0.05);从开花期到灌浆后期,Pn与气孔导度(Gs)、胞间二氧化碳浓度(Ci)总体变化趋势相同,且相关性显著,表明Pn在一定程度上受气孔因素的限制;在灌浆中后期,Rht10对Gs有明显的正效应;在抽穗和开花期,Rht10对Tr有明显的正效应;Rht10对叶片水分利用效率(WUE)在4个生育期有明显的负效应.由此可见,Rht10基因对小麦的生育期、株高、穗长都有明显的不利影响,对各项光合生理参数也有普遍正向或负向的影响,在利用Rht10进行杂交育种时应充分考虑此基因带来的不利效应.%'Lumai 15', 'Rht10 Lumai 15','Ms2 Lumai 15' and 'Ms2+Rht10 Lumai 15' as materials,were aimed to investigate the effect of Rht10 on agronomic and photosynthetic traits, such as photosynthesis (Pn) ,transpiration (Tr) ,and so on. The results showed that the materials which have Rht10 gene made the growth period 4~5 days longer than those without Rht10 gene;The plant height of' Lumai 15' and Ms2 'Lumai 15 ' was shortened by 53.77% and 53.00% with Rht10 gene, respectively; Rht10 gene also significantly shortened the spike length of wheat (P<0. 05),Rht10 can significantly decrease the kernel weight,but the effect on the spikelet number was not obvious (P>0.05) ;There were universal remarkable differences in photosynthesizes in the physiological parameter between the materials

  4. Trait values, not trait plasticity, best explain invasive species' performance in a changing environment.

    Science.gov (United States)

    Matzek, Virginia

    2012-01-01

    The question of why some introduced species become invasive and others do not is the central puzzle of invasion biology. Two of the principal explanations for this phenomenon concern functional traits: invasive species may have higher values of competitively advantageous traits than non-invasive species, or they may have greater phenotypic plasticity in traits that permits them to survive the colonization period and spread to a broad range of environments. Although there is a large body of evidence for superiority in particular traits among invasive plants, when compared to phylogenetically related non-invasive plants, it is less clear if invasive plants are more phenotypically plastic, and whether this plasticity confers a fitness advantage. In this study, I used a model group of 10 closely related Pinus species whose invader or non-invader status has been reliably characterized to test the relative contribution of high trait values and high trait plasticity to relative growth rate, a performance measure standing in as a proxy for fitness. When grown at higher nitrogen supply, invaders had a plastic RGR response, increasing their RGR to a much greater extent than non-invaders. However, invasive species did not exhibit significantly more phenotypic plasticity than non-invasive species for any of 17 functional traits, and trait plasticity indices were generally weakly correlated with RGR. Conversely, invasive species had higher values than non-invaders for 13 of the 17 traits, including higher leaf area ratio, photosynthetic capacity, photosynthetic nutrient-use efficiency, and nutrient uptake rates, and these traits were also strongly correlated with performance. I conclude that, in responding to higher N supply, superior trait values coupled with a moderate degree of trait variation explain invasive species' superior performance better than plasticity per se.

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

    African Journals Online (AJOL)

    AJL

    2012-02-21

    Feb 21, 2012 ... Full Length Research Paper ... photosynthetic measurement system, high performance liquid chromatography and SPSS13.0 software. ... net photosynthetic rate and lycorine and galantamine contents. .... Pigment analysis.

  6. Heterosis of maize photosynthetic performance

    Institute of Scientific and Technical Information of China (English)

    LI Xia; DING Zaisong; LI Lianlu; WANG Meiyun; ZHAO Ming

    2007-01-01

    Four maize inbred lines with different photosyn-thetic rates and their two hybrids were used as test materials,and the diurnal variations of their photosynthesis parameters in the silking stage were measured to study the heterosis of photosynthetic performance.Results showed that net photo-synthetic rate (In),transpiration rate (Tr) and stomatal conductance (Gs) all presented an obvious single-peaked curve in a day,with the peak values occurring at 10:00-12:00,12:00,10:00-12:00 a.m.,respectively,while water use efficiency (WUE) had a"V"type variant trend,with the lowest value appearing at 12:00.The diurnal variation of Pn and Tr was correlated markedly with Gs,suggesting that Gs played an important role in regulating the diurnal variation of Pn and Tr,and Pn,Tr and Gs had a higher heterosis in the afternoon than in the morning,while the WUE was in reverse,indicating that maize hybrid had higher resistance to the high temperature and dehydration in the afternoon,which provided a new path to select varieties with a high net photosynthetic rate.

  7. 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 phot

  8. Physiological and biogeochemical traits of bleaching and recovery in the mounding species of coral Porites lobata: implications for resilience in mounding corals.

    Directory of Open Access Journals (Sweden)

    Stephen J Levas

    Full Text Available Mounding corals survive bleaching events in greater numbers than branching corals. However, no study to date has determined the underlying physiological and biogeochemical trait(s that are responsible for mounding coral holobiont resilience to bleaching. Furthermore, the potential of dissolved organic carbon (DOC as a source of fixed carbon to bleached corals has never been determined. Here, Porites lobata corals were experimentally bleached for 23 days and then allowed to recover for 0, 1, 5, and 11 months. At each recovery interval a suite of analyses were performed to assess their recovery (photosynthesis, respiration, chlorophyll a, energy reserves, tissue biomass, calcification, δ(13C of the skeletal, δ(13C, and δ(15N of the animal host and endosymbiont fractions. Furthermore, at 0 months of recovery, the assimilation of photosynthetically acquired and zooplankton-feeding acquired carbon into the animal host, endosymbiont, skeleton, and coral-mediated DOC were measured via (13C-pulse-chase labeling. During the first month of recovery, energy reserves and tissue biomass in bleached corals were maintained despite reductions in chlorophyll a, photosynthesis, and the assimilation of photosynthetically fixed carbon. At the same time, P. lobata corals catabolized carbon acquired from zooplankton and seemed to take up DOC as a source of fixed carbon. All variables that were negatively affected by bleaching recovered within 5 to 11 months. Thus, bleaching resilience in the mounding coral P. lobata is driven by its ability to actively catabolize zooplankton-acquired carbon and seemingly utilize DOC as a significant fixed carbon source, facilitating the maintenance of energy reserves and tissue biomass. With the frequency and intensity of bleaching events expected to increase over the next century, coral diversity on future reefs may favor not only mounding morphologies but species like P. lobata, which have the ability to utilize heterotrophic

  9. Invasive Buddleja davidii allocates more nitrogen to its photosynthetic machinery than five native woody species.

    Science.gov (United States)

    Feng, Yu-Long; Auge, Harald; Ebeling, Susan K

    2007-09-01

    The general-purpose genotype hypothesis and the hypothesis of the evolution of invasiveness predict that invasive species are characterized by particular traits that confer invasiveness. However, these traits are still not well-defined. In this study, ecophysiological traits of eight populations of the invasive shrub Buddleja davidii from a wide range of European locations and five co-occurring native woody species in Germany were compared in a common garden experiment. We hypothesized that the invader has higher resource capture ability and utilization efficiency than the natives. No differences were detected among the eight populations of B. davidii in any of the traits evaluated, indicating that the invader did not evolve during range expansion, thus providing support to the general-purpose genotype hypothesis. The invader showed significantly higher maximum electron transport rate, maximum carboxylation rate, carboxylation efficiency, light-saturated photosynthetic rate (P(max)) and photosynthetic nitrogen utilization efficiency (PNUE) than the five natives. Leaf nitrogen content was not significantly different between the invader and the natives, but the invader allocated more nitrogen to the photosynthetic machinery than the natives. The increased nitrogen content in the photosynthetic machinery resulted in a higher resource capture ability and utilization efficiency in the invader. At the same intercellular CO(2) concentration, P (max) was significantly higher in the invader than in the natives, again confirming the importance of the higher nitrogen allocation to photosynthesis. The invader reduced metabolic cost by increasing the ratio of P (max) to dark respiration rate (R (d)), but it did not reduce carbon cost by increasing the specific leaf area and decreasing leaf construction cost. The higher nitrogen allocation to the photosynthetic machinery, P(max), PNUE and P(max)/R(d) may facilitate B. davidii invasion, although studies involving a wide range of

  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. Chromatic adaptation of photosynthetic membranes.

    Science.gov (United States)

    Scheuring, Simon; Sturgis, James N

    2005-07-15

    Many biological membranes adapt in response to environmental conditions. We investigated how the composition and architecture of photosynthetic membranes of a bacterium change in response to light, using atomic force microscopy. Despite large modifications in the membrane composition, the local environment of core complexes remained unaltered, whereas specialized paracrystalline light-harvesting antenna domains grew under low-light conditions. Thus, the protein mixture in the membrane shows eutectic behavior and can be mimicked by a simple model. Such structural adaptation ensures efficient photon capture under low-light conditions and prevents photodamage under high-light conditions.

  12. 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

  13. 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 r

  14. Cancer resistance as an acquired and inheritable trait

    DEFF Research Database (Denmark)

    Koch, Janne; Hau, Jann; Jensen, Henrik Elvang

    2014-01-01

    AIM: To induce cancer resistance in wild-type mice and detect if the resistance could be inherited to the progeny of the induced resistant mice. Furthermore to investigate the spectrum and immunology of this inherited cancer resistance. MATERIALS AND METHODS: Resistance to with live S180 cancer...... cells in BALB/c mice was induced by immunization with inactivated S180 cancer cells. The immunization was performed by either frozen/thawed or irradiated cancer cells or cell-free ascitic fluid (CFAF). RESULTS: In all instances the induced resistance was demonstrated to be inheritable. The phenotype...... was named HICR (heritable induced cancer resistance) and was defined as primary resistant progeny from mice immunized with frozen/thawed or irradiated S180 cells or CFAF obtained from mice with S180 induced ascites. Notably, this resistance was transferred from both male and female mice to the offspring...

  15. Leaf photosynthetic rate of tropical ferns is evolutionarily linked to water transport capacity.

    Science.gov (United States)

    Zhang, Shi-Bao; Sun, Mei; Cao, Kun-Fang; Hu, Hong; Zhang, Jiao-Lin

    2014-01-01

    Ferns usually have relatively lower photosynthetic potential than angiosperms. However, it is unclear whether low photosynthetic potential of ferns is linked to leaf water supply. We hypothesized that there is an evolutionary association of leaf water transport capacity with photosynthesis and stomatal density in ferns. In the present study, a series of functional traits relating to leaf anatomy, hydraulics and physiology were assessed in 19 terrestrial and 11 epiphytic ferns in a common garden, and analyzed by a comparative phylogenetics method. Compared with epiphytic ferns, terrestrial ferns had higher vein density (Dvein), stomatal density (SD), stomatal conductance (gs), and photosynthetic capacity (Amax), but lower values for lower epidermal thickness (LET) and leaf thickness (LT). Across species, all traits varied significantly, but only stomatal length (SL) showed strong phylogenetic conservatism. Amax was positively correlated with Dvein and gs with and without phylogenetic corrections. SD correlated positively with Amax, Dvein and gs, with the correlation between SD and Dvein being significant after phylogenetic correction. Leaf water content showed significant correlations with LET, LT, and mesophyll thickness. Our results provide evidence that Amax of the studied ferns is linked to leaf water transport capacity, and there was an evolutionary association between water supply and demand in ferns. These findings add new insights into the evolutionary correlations among traits involving carbon and water economy in ferns.

  16. Acquired inflammatory demyelinating neuropathies.

    Science.gov (United States)

    Ensrud, E R; Krivickas, L S

    2001-05-01

    The acquired demyelinating neuropathies can be divided into those with an acute onset and course and those with a more chronic course. The acute neuropathies present as Guillain-Barré syndrome and include acute inflammatory demyelinating polyradiculoneuropathy (AIDP), Miller Fisher syndrome, acute motor axonal neuropathy (AMAN), acute motor and sensory axonal neuropathy (AMSAN), and acute pandysautonomia. The chronic neuropathies are collectively known as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and include MADSAM (multifocal acquired demyelinating sensory and motor neuropathy, also know as Lewis-Sumner syndrome) and DADS (distal acquired demyelinating symmetric neuropathy) as variants. The clinical features, pathology, pathogenesis, diagnosis, treatment, rehabilitation, and prognosis of these neuropathies are discussed.

  17. Quantum coherence in photosynthetic complexes

    Energy Technology Data Exchange (ETDEWEB)

    Calhoun, Tessa R.; Fleming, Graham R. [Department of Chemistry, University of California, Berkeley, CA 94720 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2011-04-15

    The initial steps of photosynthesis require the absorption and subsequent transfer of energy through an intricate network of pigment-protein complexes. Held within the protein scaffold of these complexes, chromophore molecules are densely packed and fixed in specific geometries relative to one another resulting in Coulombic coupling. Excitation energy transfer through these systems can be accomplished with near unity quantum efficiency [Wraight and Clayton, Biochim. Biophys. Acta 333, 246 (1974)]. While replication of this feat is desirable for artificial photosynthesis, the mechanism by which nature achieves this efficiency is unknown. Recent experiments have revealed the presence of long-lived quantum coherences in photosynthetic pigment-protein complexes spanning bacterial and plant species with a variety of functions and compositions. Its ubiquitous presence and wavelike energy transfer implicate quantum coherence as key to the high efficiency achieved by photosynthesis. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Tocopherol functions in photosynthetic organisms.

    Science.gov (United States)

    Maeda, Hiroshi; DellaPenna, Dean

    2007-06-01

    During the past decade, the genes required for tocopherol (vitamin E) synthesis in plants and cyanobacteria have been identified. A series of mutants in which specific pathway steps are disrupted have been generated, providing new insights into tocopherol functions in photosynthetic organisms. Tocopherols are essential for controlling non-enzymatic lipid peroxidation during seed dormancy and seedling germination. Their absence results in elevated levels of malondialdehyde and phytoprostanes, and in inappropriate activation of plant defense responses. Surprisingly, tocopherol deficiency in mature leaves has limited consequences under most abiotic stresses, including high intensity light stress. The cell wall development of phloem transfer cells under cold conditions is, however, severely impaired in mature leaves of tocopherol-deficient mutants, indicating that tocopherols are required for proper adaptation of phloem loading at low temperatures.

  19. Hospital-acquired pneumonia

    Science.gov (United States)

    ... tends to be more serious than other lung infections because: People in the hospital are often very sick and cannot fight off ... prevent pneumonia. Most hospitals have programs to prevent hospital-acquired infections.

  20. Acquired Cutix Laxa

    Directory of Open Access Journals (Sweden)

    Jaswal Ritu

    1999-01-01

    Full Text Available A case of acquired cutis laxa in a male is reported. The skin became loose and started hanging in folds after the patient received therapy for piles. Relevant literature is reviewed.

  1. Acquired color vision deficiency.

    Science.gov (United States)

    Simunovic, Matthew P

    2016-01-01

    Acquired color vision deficiency occurs as the result of ocular, neurologic, or systemic disease. A wide array of conditions may affect color vision, ranging from diseases of the ocular media through to pathology of the visual cortex. Traditionally, acquired color vision deficiency is considered a separate entity from congenital color vision deficiency, although emerging clinical and molecular genetic data would suggest a degree of overlap. We review the pathophysiology of acquired color vision deficiency, the data on its prevalence, theories for the preponderance of acquired S-mechanism (or tritan) deficiency, and discuss tests of color vision. We also briefly review the types of color vision deficiencies encountered in ocular disease, with an emphasis placed on larger or more detailed clinical investigations.

  2. Laboratory-acquired brucellosis

    DEFF Research Database (Denmark)

    Fabiansen, C.; Knudsen, J.D.; Lebech, A.M.

    2008-01-01

    Brucellosis is a rare disease in Denmark. We describe one case of laboratory-acquired brucellosis from an index patient to a laboratory technician following exposure to an infected blood culture in a clinical microbiology laboratory Udgivelsesdato: 2008/6/9......Brucellosis is a rare disease in Denmark. We describe one case of laboratory-acquired brucellosis from an index patient to a laboratory technician following exposure to an infected blood culture in a clinical microbiology laboratory Udgivelsesdato: 2008/6/9...

  3. 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.

  4. 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.

  5. [Effects of light quality on photosynthetic pigment contents and photosynthetic characteristics of peanut seedling leaves].

    Science.gov (United States)

    Yan, Meng-Meng; Wang, Ming-Lun; Wang, Hong-Bo; Wang, Yue-Fu; Zhao, Chang-Xing

    2014-02-01

    This study explored the effects of different light quality on photosynthetic pigment contents and photosynthetic characteristics of peanut (Qinhua 6) seedling leaves. The results showed that, compared with natural light, blue light (445-470 nm) could significantly improve the specific leaf area (SLA), chlorophyll a/b value and carotenoid content of peanut seedlings. Meanwhile, the net photosynthetic rate, stomatal conductance, and transpiration rate were higher, the intercellular CO2 content was lower, and the photosynthetic efficiency was improved significantly under blue light. Red light (610-660 nm) could improve the chlorophyll content significantly, and reduce SLA, chlorophyll a/b value and carotenoid content, with a lower photosynthetic efficiency than natural light. Green light (515-520 nm) and yellow light (590-595 nm) were not conducive to photosynthetic pigment accumulation of leaves, and significantly inhibited leaf photosynthesis of peanut seedlings.

  6. Acquired smooth muscle hamartoma

    Directory of Open Access Journals (Sweden)

    Bari Arfan ul

    2006-01-01

    Full Text Available Smooth muscle hamartoma is an uncommon, usually congenital, cutaneous hyperplasia of the arrectores pilorum muscles. When it is acquired, it may be confused with Becker′s nevus. We report a case of this rare tumor in a 19-year-old man. The disease started several years ago as multiple small skin-colored papules that subsequently coalesced to form a large soft plaque on the back of the left shoulder. The diagnosis of acquired smooth muscle hamartoma was confirmed on histopathology. The patient was reassured about the benign nature of the lesion and was not advised any treatment.

  7. Leaf-level photosynthetic capacity in lowland Amazonian and high-elevation Andean tropical moist forests of Peru.

    Science.gov (United States)

    Bahar, Nur H A; Ishida, F Yoko; Weerasinghe, Lasantha K; Guerrieri, Rossella; O'Sullivan, Odhran S; Bloomfield, Keith J; Asner, Gregory P; Martin, Roberta E; Lloyd, Jon; Malhi, Yadvinder; Phillips, Oliver L; Meir, Patrick; Salinas, Norma; Cosio, Eric G; Domingues, Tomas F; Quesada, Carlos A; Sinca, Felipe; Escudero Vega, Alberto; Zuloaga Ccorimanya, Paola P; Del Aguila-Pasquel, Jhon; Quispe Huaypar, Katherine; Cuba Torres, Israel; Butrón Loayza, Rosalbina; Pelaez Tapia, Yulina; Huaman Ovalle, Judit; Long, Benedict M; Evans, John R; Atkin, Owen K

    2016-07-08

    We examined whether variations in photosynthetic capacity are linked to variations in the environment and/or associated leaf traits for tropical moist forests (TMFs) in the Andes/western Amazon regions of Peru. We compared photosynthetic capacity (maximal rate of carboxylation of Rubisco (Vcmax ), and the maximum rate of electron transport (Jmax )), leaf mass, nitrogen (N) and phosphorus (P) per unit leaf area (Ma , Na and Pa , respectively), and chlorophyll from 210 species at 18 field sites along a 3300-m elevation gradient. Western blots were used to quantify the abundance of the CO2 -fixing enzyme Rubisco. Area- and N-based rates of photosynthetic capacity at 25°C were higher in upland than lowland TMFs, underpinned by greater investment of N in photosynthesis in high-elevation trees. Soil [P] and leaf Pa were key explanatory factors for models of area-based Vcmax and Jmax but did not account for variations in photosynthetic N-use efficiency. At any given Na and Pa , the fraction of N allocated to photosynthesis was higher in upland than lowland species. For a small subset of lowland TMF trees examined, a substantial fraction of Rubisco was inactive. These results highlight the importance of soil- and leaf-P in defining the photosynthetic capacity of TMFs, with variations in N allocation and Rubisco activation state further influencing photosynthetic rates and N-use efficiency of these critically important forests.

  8. Hybrid system of semiconductor and photosynthetic protein.

    Science.gov (United States)

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

    2014-08-29

    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.

  9. Photosynthetic carbon monoxide metabolism by sugarcane leaves

    Energy Technology Data Exchange (ETDEWEB)

    Kortschak, H.P.; Nickell, L.G.

    1973-01-01

    The photosynthetic carbon monoxide metabolism by sugarcane was studied to determine whether substantial quantities of CO are removed from the air by fields in Hawaii. Leaves metabolized low CO concentrations photosynthetically, with sucrose as an end product. Rates of uptake were of the order of 10/sup -4/ power mg/d sq m/hr. This was to low to be significant in removing CO from the atmosphere.

  10. Leaf shape linked to photosynthetic rates and temperature optima in South African Pelargonium species.

    Science.gov (United States)

    Nicotra, A B; Cosgrove, M J; Cowling, A; Schlichting, C D; Jones, C S

    2008-01-01

    The thermal response of gas exchange varies among plant species and with growth conditions. Plants from hot dry climates generally reach maximal photosynthetic rates at higher temperatures than species from temperate climates. Likewise, species in these environments are predicted to have small leaves with more-dissected shapes. We compared eight species of Pelargonium (Geraniaceae) selected as phylogenetically independent contrasts on leaf shape to determine whether: (1) the species showed plasticity in thermal response of gas exchange when grown under different water and temperature regimes, (2) there were differences among more- and less-dissected leafed species in trait means or plasticity, and (3) whether climatic variables were correlated with the responses. We found that a higher growth temperature led to higher optimal photosynthetic temperatures, at a cost to photosynthetic capacity. Optimal temperatures for photosynthesis were greater than the highest growth temperature regime. Stomatal conductance responded to growth water regime but not growth temperature, whereas transpiration increased and water use efficiency (WUE) decreased at the higher growth temperature. Strikingly, species with more-dissected leaves had higher rates of carbon gain and water loss for a given growth condition than those with less-dissected leaves. Species from lower latitudes and lower rainfall tended to have higher photosynthetic maxima and conductance, but leaf dissection did not correlate with climatic variables. Our results suggest that the combination of dissected leaves, higher photosynthetic rates, and relatively low WUE may have evolved as a strategy to optimize water delivery and carbon gain during short-lived periods of high soil moisture. Higher thermal optima, in conjunction with leaf dissection, may reflect selection pressure to protect photosynthetic machinery against excessive leaf temperatures when stomata close in response to water stress.

  11. Learning to Acquire

    DEFF Research Database (Denmark)

    Henningsson, Stefan

    2015-01-01

    This paper develops a knowledge-based model of information systems (IS) integration in acquisition-based growth programs. Previous research has found important differences in the acquirers’ abilities for acquisition IS integration, and that these differences play key roles in explaining the econo...... are therefore persistent and hard to overcome for the inexperienced acquirer....

  12. Acquired cutis laxa

    Directory of Open Access Journals (Sweden)

    Musaliar S

    2003-03-01

    Full Text Available A 13-yeat-old male patient born of non consanguineous marriage with history of recurrent urticaria and angioedema for the past 2 years presented with wrinkling and laxity of the skin over the face, axilla and abdomen. Histopathology was consistent with cutis laxa. We are reporting a rare case of acquired cutis laxa due to recurrent urticaria.

  13. Acquired cutis laxa

    Directory of Open Access Journals (Sweden)

    Musaliar S

    2003-01-01

    Full Text Available A 13-yeat-old male patient born of non consanguineous marriage with history of recurrent urticaria and angioedema for the past 2 years presented with wrinkling and laxity of the skin over the face, axilla and abdomen. Histopathology was consistent with cutis laxa. We are reporting a rare case of acquired cutis laxa due to recurrent urticaria.

  14. Photosynthetic light reactions--an adjustable hub in basic production and plant immunity signaling.

    Science.gov (United States)

    Kangasjärvi, Saijaliisa; Tikkanen, Mikko; Durian, Guido; Aro, Eva-Mari

    2014-08-01

    Photosynthetic efficiency is a key trait that influences the sustainable utilization of plants for energy and nutrition. By now, extensive research on photosynthetic processes has underscored important structural and functional relationships among photosynthetic thylakoid membrane protein complexes, and their roles in determining the productivity and stress resistance of plants. Photosystem II photoinhibition-repair cycle, for example, has arisen vital in protecting also Photosystem I against light-induced damage. Availability of highly sophisticated genetic, biochemical and biophysical tools has greatly expanded the catalog of components that carry out photoprotective functions in plants. On thylakoid membranes, these components encompass a network of overlapping systems that allow delicate regulation of linear and cyclic electron transfer pathways, balancing of excitation energy distribution between the two photosystems and dissipation of excess light energy in the antenna system as heat. An increasing number of reports indicate that the above mentioned mechanisms also mediate important functions in the regulation of biotic stress responses in plants. Particularly the handling of excitation energy in the light harvesting II antenna complexes appears central to plant immunity signaling. Comprehensive understanding of the underlying mechanisms and regulatory cross-talk, however, still remain elusive. This review highlights the current understanding of components that regulate the function of photosynthetic light reactions and directly or indirectly also modulate disease resistance in higher plants. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  15. Acquired methemoglobinemia in infants

    Directory of Open Access Journals (Sweden)

    Mehmet Mutlu

    2011-06-01

    Full Text Available Objective: This study aimed to determine the etiologic factors of acquired methemoglobinemia in infants younger than three months in our region. Material and Methods: This study was carried out retrospectively in infants with methemoglobinemia admitted to Karadeniz Technical University, Pediatric Clinic, during the period 2000-2009. Infants with methemoglobinemia were identified according to the medical records or ICD-10 code. Results: Nine infants with acquired methemoglobinemia (8 male, 1 female were included in the study. Seven cases were associated with the use of prilocaine for circumcision, one case with the use of prilocaine-lidocaine for local pain therapy, and one case with neonatal sepsis caused by Staphylococcus aureus.Conclusion: Prilocaine should not be used in infants less than three months of age because of the risk of methemoglobinemia. Ascorbic acid is an effective therapy if methylene blue is not obtained. It should not be forgotten that sepsis caused by S. aureus may cause methemoglobinemia in infants.

  16. Racks to acquire

    CERN Multimedia

    2004-01-01

    IT department has 25 80cm deep SCHROFF 19" racks which are no longer needed. Please contact Michel Blanc (Michel.Blanc@cern.ch, 74925 or 163223) from Monday 27th September if you are interested in acquiring some or all of these racks. Five shelf units suitable for housing up to 44 mini-tower PCs are also available. Photographs of racks and shelf units are available in the directory \\\\cern.ch\\dfs\\users\\t\\tim\\Public\\513.

  17. Acquired hypertrichosis lanuginosa

    Directory of Open Access Journals (Sweden)

    Kumar Pramod

    1993-01-01

    Full Text Available Acquired hypertirichosis lanuginose developed rapidly in a patient with no detectable malignancy. Soft, fine, downy hair growth was noticed on the face, ears, limbs and trunk. Bilaterally symmetrical vitiliginous macules were present on the ear and preauricular region. This case is reported because of its rarity, absence of any detectable malignancy and development of vitiligo, which to our knowledge has not been reported earlier.

  18. The photosynthetic apparatus and its regulation in the aerobic gammaproteobacterium Congregibacter litoralis gen. nov., sp. nov.

    Directory of Open Access Journals (Sweden)

    Stefan Spring

    Full Text Available BACKGROUND: There is accumulating evidence that in some marine environments aerobic bacteriochlorophyll a-producing bacteria represent a significant part of the microbial population. The interaction of photosynthesis and carbon metabolism in these interesting bacteria is still largely unknown and requires further investigation in order to estimate their contribution to the marine carbon cycle. METHODOLOGY/PRINCIPAL FINDINGS: Here, we analyzed the structure, composition and regulation of the photosynthetic apparatus in the obligately aerobic marine gammaproteobacterium KT71(T. Photoheterotrophically grown cells were characterized by a poorly developed lamellar intracytoplasmic membrane system, a type 1 light-harvesting antenna complex and a photosynthetic reaction center associated with a tetraheme cytochrome c. The only photosynthetic pigments produced were bacteriochlorophyll a and spirilloxanthin. Under semiaerobic conditions KT71(T cells expressing a photosynthetic apparatus showed a light-dependent increase of growth yield in the range of 1.3-2.5 fold. The expression level of the photosynthetic apparatus depended largely on the utilized substrate, the intermediary carbon metabolism and oxygen tension. In addition, pigment synthesis was strongly influenced by light, with blue light exerting the most significant effect, implicating that proteins containing a BLUF domain may be involved in regulation of the photosynthetic apparatus. Several phenotypic traits in KT71(T could be identified that correlated with the assumed redox state of growing cells and thus could be used to monitor the cellular redox state under various incubation conditions. CONCLUSIONS/SIGNIFICANCE: In a hypothetical model that explains the regulation of the photosynthetic apparatus in strain KT71(T we propose that the expression of photosynthesis genes depends on the cellular redox state and is maximal under conditions that allow a balanced membrane redox state. So far

  19. Acquired hyperostosis syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Dihlmann, W.; Hering, L.; Bargon, G.W.

    1988-10-01

    Sterno-costo-clavicular hyperostosis (SCCH) is the most common manifestation of a syndrome, consisting of increased bone metabolism, mostly new bone formation and heterotopic ossification of fibrous tissue, which we have characterised as the acquired hyperostosis syndrome. In part I we discuss the terminology, radiological appearances, scintigraphy, clinical and laboratory findings, bacteriology, histology, nosology, complications, treatment and differential diagnosis of SCCH. Chronic recurrent multifocal osteomyelitis (CRMO) is regarded as a phaenotype of SCCH, depending on the age. CRMO occurs in children, adolescents and young adults, SCCH predominantly in middleaged and elderly adults.

  20. Acquired von Willebrand Syndrome

    Institute of Scientific and Technical Information of China (English)

    郭涛

    2005-01-01

    @@ Acquired von Willebrand syndrome (AvWS) is kind of bleeding disorder with laboratory findings similar to those in congenital yon Willebrand disease (vWD).AvWS doesn's have any personal or family history of bleeding, but is associated with certain diseases or abnormal conditions or drugs. Although AvWS is being stated as a rare disease, it has gained more and more attention during the past years. Not because of the severity of the disease, but it is more common than we thought and most patients don' t have a proper diagnosis.

  1. "Ready to Acquire"

    DEFF Research Database (Denmark)

    Yetton, Philip; Henningsson, Stefan; Bjørn-Andersen, Niels

    2013-01-01

    This article describes the experiences of Danisco (a global food ingredients company) as it followed a growth-by-acquisition business strategy, focusing on how a new CIO built the IT resources to ensure the IT organization was "ready to acquire." We illustrate how these IT capabilities expedited...... the IT integration following two acquisitions, one of which involved Danisco expanding the scale of its business and the other extending the scope. Based on insights gained from Danisco, we provide lessons for CIOs to realize business benefits when managing post-acquisition IT integration....

  2. Enhanced practical photosynthetic CO2 mitigation

    Science.gov (United States)

    Bayless, David J.; Vis-Chiasson, Morgan L.; Kremer, Gregory G.

    2003-12-23

    This process is unique in photosynthetic carbon sequestration. An on-site biological sequestration system directly decreases the concentration of carbon-containing compounds in the emissions of fossil generation units. In this process, photosynthetic microbes are attached to a growth surface arranged in a containment chamber that is lit by solar photons. A harvesting system ensures maximum organism growth and rate of CO.sub.2 uptake. Soluble carbon and nitrogen concentrations delivered to the cyanobacteria are enhanced, further increasing growth rate and carbon utilization.

  3. Learning-by-Being-Acquired

    DEFF Research Database (Denmark)

    Colombo, Massimo Gaetano; Moreira, Solon; Rabbiosi, Larissa

    2016-01-01

    of new teams with both inventors of the acquiring and acquired firms-and assess the impact of this integration action in the period that immediately follows the acquisition. Drawing on social identity and self-categorization theories, we argue that R&D team reorganization increases the acquired inventors......’ use of the prior stock of technological knowledge of the acquiring firm after the acquisition. Furthermore, this effect is enhanced if the focal acquired inventor has high relative innovation ability but is weakened for acquired inventors with high ingroup collaborative strength. We construct a sample...

  4. Learning-By-Being-Acquired

    DEFF Research Database (Denmark)

    Colombo, Massimo G.; Moreira, Solon; Rabbiosi, Larissa

    In this paper we study post-acquisition integration in terms of R&D team reorganization—i.e., the creation of new teams with both inventors of the acquiring and acquired firms—and assess its impact on knowledge transfer in the period that follows the acquisition. Drawing on social identity and self......-categorization theories, we argue that R&D team reorganization increases the acquired inventors’ use of the prior stock of technological knowledge of the acquiring firm after the acquisition. Furthermore, this effect is enhanced if acquired inventors have higher innovation ability relative to their acquiring peers...

  5. Novel adaptive photosynthetic characteristics of mesophotic symbiotic microalgae within the reef-building coral, Stylophora pistillata

    Directory of Open Access Journals (Sweden)

    Shai Einbinder

    2016-10-01

    Full Text Available Photosynthetic coral reef structures extend from the shallow sundrenched waters to the dimly lit, twilight mesophotic depths. For their resident endosymbiotic dinoflagellates, primarily from the genus Symbiodinium spp., this represents a photic environment that varies ~15 fold in intensity and also differs in spectral composition. We examined photosynthesis in the scleractinian coral Stylophora pistillata in shallow (3 m and mesophotic settings (65m in the northern Red Sea. Symbiodinium spp. in corals originating from the mesophotic environment consistently performed below their photosynthetic compensation point and also exhibited distinct light harvesting antenna organization. In addition, the non-photochemical quenching activity of Symbiodinium spp. from mesophotic corals was shown to be considerably lower than those found in shallow corals, showing they have fewer defenses to high-light settings. Over a period of almost four years, we extensively utilized closed circuit Trimix rebreather diving to perform the study. Phylogenetic analysis showed that shallow corals (3m transplanted to a deep reef environment (65 m maintained their initial Symbiodinium spp. community (clade A, rather than taking on deep low-light clades (clade C, demonstrating that shallow S. pistillata acclimate to low-light mesophotic environments while maintaining their shallow photosynthetic traits. Mesophotic corals exhibited static depth-related chlorophyll content per cell, a decrease in PSI activity and enhanced sigmoidal fluorescence rise kinetics. The sigmoidal fluorescence rise kinetics we observed in mesophotic corals is an indication of energy transfer between photosynthetic units. We postulate that at mesophotic depths, a community of adapted Symbiodinium spp. utilize a unique adaptation to lower light conditions by shifting their light harvesting to a PSII based system, where PSII is structured near PSI, with additional PCP soluble antenna also trapping light

  6. Uncertainty quantified trait predictions

    Science.gov (United States)

    Fazayeli, Farideh; Kattge, Jens; Banerjee, Arindam; Schrodt, Franziska; Reich, Peter

    2015-04-01

    Functional traits of organisms are key to understanding and predicting biodiversity and ecological change, which motivates continuous collection of traits and their integration into global databases. Such composite trait matrices are inherently sparse, severely limiting their usefulness for further analyses. On the other hand, traits are characterized by the phylogenetic trait signal, trait-trait correlations and environmental constraints, all of which provide information that could be used to statistically fill gaps. We propose the application of probabilistic models which, for the first time, utilize all three characteristics to fill gaps in trait databases and predict trait values at larger spatial scales. For this purpose we introduce BHPMF, a hierarchical Bayesian extension of Probabilistic Matrix Factorization (PMF). PMF is a machine learning technique which exploits the correlation structure of sparse matrices to impute missing entries. BHPMF additionally utilizes the taxonomic hierarchy for trait prediction. Implemented in the context of a Gibbs Sampler MCMC approach BHPMF provides uncertainty estimates for each trait prediction. We present comprehensive experimental results on the problem of plant trait prediction using the largest database of plant traits, where BHPMF shows strong empirical performance in uncertainty quantified trait prediction, outperforming the state-of-the-art based on point estimates. Further, we show that BHPMF is more accurate when it is confident, whereas the error is high when the uncertainty is high.

  7. Identification of large variation in the photosynthetic induction response among 37 soybean [Glycine max (L.) Merr.] genotypes that is not correlated with steady-state photosynthetic capacity.

    Science.gov (United States)

    Soleh, M A; Tanaka, Y; Kim, S Y; Huber, S C; Sakoda, K; Shiraiwa, T

    2017-03-01

    Irradiance continuously fluctuates during the day in the field. The speed of the induction response of photosynthesis in high light affects the cumulative carbon gain of the plant and could impact growth and yield. The photosynthetic induction response and its relationship with the photosynthetic capacity under steady-state conditions (P max) were evaluated in 37 diverse soybean [Glycine max (L.) Merr.] genotypes. The induction response of leaf photosynthesis showed large variation among the soybean genotypes. After 5 min illumination with strong light, genotype NAM23 had the highest leaf photosynthetic rate of 33.8 µmol CO2 m(-2) s(-1), while genotype NAM12 showed the lowest rate at 4.7 µmol CO2 m(-2) s(-1). Cumulative CO2 fixation (CCF) during the first 5 min of high light exposure ranged from 5.5 mmol CO2 m(-2) for NAM23 to 0.81 mmol CO2 m(-2) for NAM12. The difference in the induction response among genotypes was consistent throughout the growth season. However, there was no significant correlation between CCF and P max among genotypes suggesting that different mechanisms regulate P max and the induction response. The observed variation in the induction response was mainly attributed to ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activation, but soybean lines differing in the induction response did not differ in the leaf content of Rubisco activase α- and β-proteins. Future studies will be focused on identifying molecular determinants of the photosynthetic induction response and determining whether this trait could be an important breeding target to achieve improved growth of soybeans in the field.

  8. 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

  9. 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 prote

  10. 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 prote

  11. Nonlinear optical absorption of photosynthetic pigment molecules in leaves.

    Science.gov (United States)

    Ye, Zi-Piao

    2012-04-01

    A mathematical formulation of the relationship between optical absorption coefficient of photosynthetic pigment molecules and light intensity was developed. It showed that physical parameters of photosynthetic pigment molecule (i.e., light absorption cross-section of photosynthetic pigment molecule, its average lifetime in the excited state, total photosynthetic pigment molecules, the statistical weight, or degeneracy of energy level of photosynthetic pigment molecules in the ground state and in the excited state) influenced on both the light absorption coefficient and effective light absorption cross-section of photosynthetic pigment molecules. Moreover, it also showed that both the light absorption coefficient and effective light absorption cross-section of photosynthetic pigment molecules were not constant, they decreased nonlinearly with light intensity increasing. The occupation numbers of photosynthetic pigment molecules in the excited states increased nonlinearly with light intensity increasing.

  12. Longitudinal photosynthetic gradient in crust lichens' thalli.

    Science.gov (United States)

    Wu, Li; Zhang, Gaoke; Lan, Shubin; Zhang, Delu; Hu, Chunxiang

    2014-05-01

    In order to evaluate the self-shading protection for inner photobionts, the photosynthetic activities of three crust lichens were detected using Microscope-Imaging-PAM. The false color images showed that longitudinal photosynthetic gradient was found in both the green algal lichen Placidium sp. and the cyanolichen Peltula sp. In longitudinal direction, all the four chlorophyll fluorescence parameters Fv/Fm, Yield, qP, and rETR gradually decreased with depth in the thalli of both of these two lichens. In Placidium sp., qN values decreased with depth, whereas an opposite trend was found in Peltula sp. However, no such photosynthetic heterogeneity was found in the thalli of Collema sp. in longitudinal direction. Microscope observation showed that photobiont cells are compactly arranged in Placidium sp. and Peltula sp. while loosely distributed in Collema sp. It was considered that the longitudinal photosynthetic heterogeneity was ascribed to the result of gradual decrease of incidence caused by the compact arrangement of photobiont cells in the thalli. The results indicate a good protection from the self-shading for the inner photobionts against high radiation in crust lichens.

  13. Natural strategies for photosynthetic light harvesting

    NARCIS (Netherlands)

    Croce, R.; Amerongen, van 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

  14. Photosynthetic antenna engineering to improve crop yields.

    Science.gov (United States)

    Kirst, Henning; Gabilly, Stéphane T; Niyogi, Krishna K; Lemaux, Peggy G; Melis, Anastasios

    2017-05-01

    Evidence shows that decreasing the light-harvesting antenna size of the photosystems in tobacco helps to increase the photosynthetic productivity and plant canopy biomass accumulation under high-density cultivation conditions. Decreasing, or truncating, the chlorophyll antenna size of the photosystems can theoretically improve photosynthetic solar energy conversion efficiency and productivity in mass cultures of algae or plants by up to threefold. A Truncated Light-harvesting chlorophyll Antenna size (TLA), in all classes of photosynthetic organisms, would help to alleviate excess absorption of sunlight and the ensuing wasteful non-photochemical dissipation of excitation energy. Thus, solar-to-biomass energy conversion efficiency and photosynthetic productivity in high-density cultures can be increased. Applicability of the TLA concept was previously shown in green microalgae and cyanobacteria, but it has not yet been demonstrated in crop plants. In this work, the TLA concept was applied in high-density tobacco canopies. The work showed a 25% improvement in stem and leaf biomass accumulation for the TLA tobacco canopies over that measured with their wild-type counterparts grown under the same ambient conditions. Distinct canopy appearance differences are described between the TLA and wild type tobacco plants. Findings are discussed in terms of concept application to crop plants, leading to significant improvements in agronomy, agricultural productivity, and application of photosynthesis for the generation of commodity products in crop leaves.

  15. Mechanism of photoprotection in photosynthetic proteins

    OpenAIRE

    TRSKOVÁ, Eliška

    2015-01-01

    Nonphotochemical quenching is an important protective mechanism of photosynthetic proteins against excessive irradiation. In this work, isolation of native light harvesting antennae from alga Chromera velia was optimized using methods of sucrose density centrifugation, isoelectric focusing, ion exchange chromatography and gel electrophoresis. Moreover, the ability of light harvesting antennae to trigger nonphotochemical quenching was studied in vivo and in vitro.

  16. Effects of salt stress on photosynthetic characteristics and some physiological traits of rice varieties at different nitrogen levels%不同供氮水平下盐胁迫对水稻光合特性和某些生理特性的影响

    Institute of Scientific and Technical Information of China (English)

    刘晓龙; 徐晨; 徐克章; 崔菁菁; 张治安; 凌凤楼; 安久海; 武志海

    2015-01-01

    Objective]To understand the response to salt stress on rice varieties cultured at different nitro-gen levels.[Method]Two north japonica rice varieties were cultured at five nitrogen levels of nutrient so-lution until booting stage , the changes of biomass , photosynthetic characteristics and some physiological characteristics of two rice varieties were measured in three salt concentrations .[Result and conclusion]The biomass of rice varieties which were cultured at different nitrogen levels of nutrient solution decreased under salt stress;there were significant decrease in net photosynthetic rate ( Pn) , stomatal conductance (Gs), transpiration rate ( Tr) and apparent mesophyll conductance ( AMC) of rice leaves under salt stress.The Pn reduction was due to non-stomatal restriction factors in low-nitrogen-level nutrient solu-tion, however, the stomatal and non-stomatal limitation factors resulted in the Pn reduction in high-nitro-gen-level nutrient solution .Under salt stress , the activity of antioxidant enzymes such as SOD , POD and CAT, the contents of proline and soluble sugar of leaves in 1/2N-level nutrient solution were significantly higher than those at other nitrogen-levels, the membrane permeability and the content of MDA in 1/2N-level were lower than those at other nitrogen-levels.The results show that rice varieties cultured in 1/2N-level nutrient solution can improve the capacity of osmotic regulation , enhancing the salt-tolerance ability of rice varieties at booting stage .The capacity of salt-tolerance of Jiudao 13 is higher than that of Jijing 88 .%目的为了解不同供氮水平培养的水稻植株对盐胁迫的响应.方法以2个北方常规粳稻品种为材料,在5个供氮水平下培养至孕穗期,以3个盐浓度进行胁迫处理,研究了处理后的水稻植株生物量、光合特性及一些生理特性的变化.结果和结论不同供氮水平培养的水稻植株在盐胁迫后生物量均呈

  17. Surgical treatment of acquired tracheocele.

    Science.gov (United States)

    Porubsky, Edward A; Gourin, Christine G

    2006-06-01

    Acquired tracheoceles are rare clinical entities that can cause a variety of chronic and recurrent aerodigestive tract symptoms. The management of acquired tracheoceles is primarily conservative, but surgical intervention may be indicated for patients with refractory symptoms. We present a case of acquired tracheocele and describe a method of successful surgical management.

  18. Mosaic origin of the heme biosynthesis pathway in photosynthetic eukaryotes.

    Science.gov (United States)

    Oborník, Miroslav; Green, Beverley R

    2005-12-01

    Heme biosynthesis represents one of the most essential metabolic pathways in living organisms, providing the precursors for cytochrome prosthetic groups, photosynthetic pigments, and vitamin B(12). Using genomic data, we have compared the heme pathway in the diatom Thalassiosira pseudonana and the red alga Cyanidioschyzon merolae to those of green algae and higher plants, as well as to those of heterotrophic eukaryotes (fungi, apicomplexans, and animals). Phylogenetic analyses showed the mosaic character of this pathway in photosynthetic eukaryotes. Although most of the algal and plant enzymes showed the expected plastid (cyanobacterial) origin, at least one of them (porphobilinogen deaminase) appears to have a mitochondrial (alpha-proteobacterial) origin. Another enzyme, glutamyl-tRNA synthase, obviously originated in the eukaryotic nucleus. Because all the plastid-targeted sequences consistently form a well-supported cluster, this suggests that genes were either transferred from the primary endosymbiont (cyanobacteria) to the primary host nucleus shortly after the primary endosymbiotic event or replaced with genes from other sources at an equally early time, i.e., before the formation of three primary plastid lineages. The one striking exception to this pattern is ferrochelatase, the enzyme catalyzing the first committed step to heme and bilin pigments. In this case, two red algal sequences do not cluster either with the other plastid sequences or with cyanobacterial sequences and appear to have a proteobacterial origin like that of the apicomplexan parasites Plasmodium and Toxoplasma. Although the heterokonts also acquired their plastid via secondary endosymbiosis from a red alga, the diatom has a typical plastid-cyanobacterial ferrochelatase. We have not found any remnants of the plastidlike heme pathway in the nonphotosynthetic heterokonts Phytophthora ramorum and Phytophthora sojae.

  19. Comparative Mechanisms of Photosynthetic Carbon Acquisitionin Hizikiafusiforme Under Submersed and Emersed Conditions

    Institute of Scientific and Technical Information of China (English)

    ZOUDing-Hui; GAOKun-Shan

    2004-01-01

    The economic seaweed Hizikia fusiforme (Harv.) Okamura (Sargassaceae, Phaeophyta) usually experiences periodical exposures to air at low tide. Photosynthetic carbon acquisition mechanisms were comparatively studied under submersed and emersed conditions in order to establish a general understanding of its photosynthetic characteristics associated with tidal cycles. When submersed in seawater, H.fusiforme was capable of acquiring HCO3- as a source of inorganic carbon (Ci) to drive photosynthesis, while emersed and exposed to air, it used atmospheric 002 for photosynthesis. The pH changes surroundingthe H.fusiforme fronds had less influence on the photosynthetic rates under emersed condition than under submersed condition. When the pH was as high as 10.0, emersed H.fusiforme could photosynthesize efficiently, but the submersed alga exhibited very poor photosynthesis. Extracellular carbonic anhydrase (CA) played an important role in the photosynthetic acquisitions of exogenous Ci in water as well as in air. Both the concentrations of dissolved inorganic carbon in general seawater and CO2 in air were demonstrated to limit the photosynthesis of H.fusiforme, which was sensitive to O2. It appeared that the exogenous carbon acquisition system, being dependent of external CA activity, operates in a way not enough to raise intracellular CO2 level to prevent photorespiration. The inability of H.fusiforme to achieve its maximum photosynthetic rate at the current ambient Ci levels under both submersed and emersed conditions suggested that the yield of aquaculture for this economic species would respond profitably to future increases in CO2 concentration in the sea and air.

  20. Evaluating the Importance of Plant Functional Traits: the Subalpine and Alpine

    Science.gov (United States)

    Sanchez, A.; Smith, W. K.

    2011-12-01

    Over the past several decades, researchers have attempted to characterize plant groups according to traits that are considered functional, i.e. contributing significantly to fitness. Due to the complexity of measuring fitness, the capability for photosynthetic carbon gain is often used as a proxy. Thus, this approach correlates structural differences to photosynthetic performance, especially those differences that are known to be associated with photosynthesis, are easily measured and inexpensive. At the often sharp boundary between the subalpine forest and alpine community (treeline ecotone), plant structural traits change dramatically, i.e. tall evergreen trees give way abruptly to low-stature shrubs, grasses, forbs, and herbs. Yet, the differences in functional traits, so abundant in the literature for a variety of species and communities, have not been compared contiguous communities such as the subalpine forest and alpine. Can differences in functional traits already identified in the literature also be used to characterize species of these two contrasting communities? Or are there other traits that are most functional and/or, possibly, unique to each community and not the most popular traits reported so far in the literature. Also, does the community structure itself help determine functional traits? For example, the top ten most frequently studied traits (145 total papers from approximately 63 different refereed journals) considered functional include the following (% of the 145 publications): specific leaf area or mass (SLA or SLM 39%), plant height (36%), leaf nitrogen content (34%), leaf size (19%), leaf area (16%), leaf photosynthetic performance (15%), leaf dry matter content (LDMC 15%), leaf mass per unit leaf area (LMA 15%), leaf thickness (15%), and seed mass (14%). In addition, another 120 traits were mentioned as functional, although all fell below a 14% citation rate. Particular focus was placed on this group due to the possibility that they might

  1. ICU-Acquired Weakness.

    Science.gov (United States)

    Jolley, Sarah E; Bunnell, Aaron E; Hough, Catherine L

    2016-11-01

    Survivorship after critical illness is an increasingly important health-care concern as ICU use continues to increase while ICU mortality is decreasing. Survivors of critical illness experience marked disability and impairments in physical and cognitive function that persist for years after their initial ICU stay. Newfound impairment is associated with increased health-care costs and use, reductions in health-related quality of life, and prolonged unemployment. Weakness, critical illness neuropathy and/or myopathy, and muscle atrophy are common in patients who are critically ill, with up to 80% of patients admitted to the ICU developing some form of neuromuscular dysfunction. ICU-acquired weakness (ICUAW) is associated with longer durations of mechanical ventilation and hospitalization, along with greater functional impairment for survivors. Although there is increasing recognition of ICUAW as a clinical entity, significant knowledge gaps exist concerning identifying patients at high risk for its development and understanding its role in long-term outcomes after critical illness. This review addresses the epidemiologic and pathophysiologic aspects of ICUAW; highlights the diagnostic challenges associated with its diagnosis in patients who are critically ill; and proposes, to our knowledge, a novel strategy for identifying ICUAW. Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

  2. Acquiring specific interpreting competence

    Directory of Open Access Journals (Sweden)

    Jana Zidar Forte

    2012-12-01

    Full Text Available In postgraduate interpreter training, the main objective of the course is to help trainees develop various competences, from linguistic, textual and cultural competence, to professional and specific interpreting competence. For simultaneous interpreting (SI, the main focus is on mastering the SI technique and strategies as well as on developing and strengthening communicative skills, which is discussed and illustrated with examples in the present paper. First, a brief overview is given of all the necessary competences of a professional interpreter with greater emphasis on specific interpreting competence for SI. In the second part of the paper, various approaches are described in terms of acquiring specific skills and strategies, specifically through a range of exercises. Besides interpreting entire speeches, practical courses should also consist of targeted exercises, which help trainees develop suitable coping strategies and mechanisms (later on almost automatisms, while at the same time "force" them to reflect on their individual learning process and interpreting performance. This provides a solid base on which trained interpreters can progress and develop their skills also after joining the professional sphere.

  3. Traits traded off

    NARCIS (Netherlands)

    Rueffler, Claus

    2006-01-01

    The course of evolution is restricted by constraints. A special type of constraint is a trade-off where different traits are negatively correlated. In this situation a mutant type that shows an improvement in one trait suffers from a decreased performance through another trait. In a fixed fitness la

  4. Comparative Genomic Study of the Thioredoxin Family in Photosynthetic Organisms with Emphasis on Populus trichocarpa

    Institute of Scientific and Technical Information of China (English)

    Kamel Chibani; Gunnar Wingsle; Jean-Pierre Jacquot; Eric Gelhaye; Nicolas Rouhier

    2009-01-01

    The recent genome sequencing of Populus trichocarpa and Vitis vinifera, two models of woody plants, of Sorghum bicolor, a model of monocot using C4 metabolism, and of the moss Physcomitrella patens, together with the availability of photosynthetic organism genomes allows performance of a comparative genomic study with organisms having different ways of life, reproduction modes, biological traits, and physiologies. Thioredoxins (Trxs) are small ubiq-uitous proteins involved in the reduction of disulfide bridges in a variety of target enzymes present in all sub-cellular compartments and involved in many biochemical reactions. The genes coding for these enzymes have been identified in these newly sequenced genomes and annotated. The gene content, organization and distribution were compared to other photosynthetic organisms, leading to a refined classification. This analysis revealed that higher plants and bryo-phytes have a more complex family compared to algae and cyanobacteria and to non-photosynthetic organisms, since poplar exhibits 49 genes coding for typical and atypical thioredoxins and thioredoxin reductases, namely one-third more than monocots such as Oryza sativa and S. bicolor. The higher number of Trxs in poplar is partially explained by gene duplication in the Trx m, h, and nucleoredoxin classes. Particular attention was paid to poplar genes with emphasis on Trx-like classes called Clot, thioredoxin-like, thioredoxins of the lilium type and nucleoredoxins, which were not described in depth in previous genomic studies.

  5. Correlated interaction fluctuations in photosynthetic complexes

    CERN Document Server

    Vlaming, Sebastiaan M

    2011-01-01

    The functioning and efficiency of natural photosynthetic complexes is strongly influenced by their embedding in a noisy protein environment, which can even serve to enhance the transport efficiency. Interactions with the environment induce fluctuations of the transition energies of and interactions between the chlorophyll molecules, and due to the fact that different fluctuations will partially be caused by the same environmental factors, correlations between the various fluctuations will occur. We argue that fluctuations of the interactions should in general not be neglected, as these have a considerable impact on population transfer rates, decoherence rates and the efficiency of photosynthetic complexes. Furthermore, while correlations between transition energy fluctuations have been studied, we provide the first quantitative study of the effect of correlations between interaction fluctuations and transition energy fluctuations, and of correlations between the various interaction fluctuations. It is shown t...

  6. Photosynthetic rates of citronella and lemongrass.

    Science.gov (United States)

    Herath, H M; Ormrod, D P

    1979-02-01

    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 meter(2) 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.

  7. Photosynthetic rates influence the population dynamics of understory herbs in stochastic light environments.

    Science.gov (United States)

    Westerband, Andrea C; Horvitz, Carol C

    2017-02-01

    Temporal variability in light from gaps in the tree canopy strongly influences the vital rates of understory plants. From 2012 to 2015, we estimated the size-specific vital rates of two herbs, Calathea crotalifera and Heliconia tortuosa, over a range of light environments. We estimated maximum photosynthetic capacity (Amax ) for a subset of individuals each year during three annual censuses, and modelled future size as a linear function of current size (a plant trait that changes ontogenetically), canopy openness (an environmental variable), and Amax (a potentially plastic physiological trait). We estimated what the demographic success would be of a population comprised of individuals with a particular fixed Amax for each of several levels of canopy openness if the environment remained constant, by evaluating corresponding Integral Projection Models and their deterministic growth rates (λ). We then estimated their demographic success in the stochastic light environment (λS ) and its elasticities. As light increased, deterministic λ increased for Calathea by 33% but decreased for Heliconia by 52%, and increasing Amax had no effect on λ for Calathea but increased λ for Heliconia in low light. As Amax increased, λS increased for Heliconia, but not Calathea. We also investigated whether photosynthetic rates would influence the elasticities of λS, including its response to perturbation of vital rates in each environment (E(S)β ), vital rates over all environments (E(S) ), and variability of vital rates among environments (E(S)(σ) ). E(S) , E(S)(σ) , and E(S)β were influenced by Amax for Heliconia but not Calathea. Events that affect some vital rates in high light have a greater impact on overall fitness than events that affect the same vital rates in shady environments, and there is greater potential for selection on traits of large individuals in high light than in low light for Heliconia, while the reverse was true for Calathea. Photosynthetic rates

  8. Nonclassical energy transfer in photosynthetic FMO complex

    Directory of Open Access Journals (Sweden)

    Abramavicius Vytautas

    2013-03-01

    Full Text Available Excitation energy transfer in a photosynthetic FMO complex has been simulated using the stochastic Schrödinger equation. Fluctuating chromophore transition energies are simulated from the quantum correlation function which allows to properly include the finite temperature. The resulting excitation dynamics shows fast thermalization of chromophore occupations into proper thermal equilibrium. The relaxation process is characterized by entropy dynamics, which shows nonclassical behavior.

  9. 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.

  10. 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.

  11. 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

    2003-04-15

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 1/2/2003 through 4/01/2003. As indicated in the list of accomplishments below we are progressing with long-term model scale bioreactor tests and are completing final preparations for pilot scale bioreactor testing. Specific results and accomplishments for the first quarter of 2003 are included.

  12. Using Phenomic Analysis of Photosynthetic Function for Abiotic Stress Response Gene Discovery

    KAUST Repository

    Rungrat, Tepsuda

    2016-09-09

    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 stress factors, which limits their growth rates in the natural environment. Arabidopsis thaliana, with its broad genetic diversity and wide climatic range, has been shown to successfully adapt to stressful conditions to ensure the completion of its life cycle. As a result, A. thaliana has become a robust and renowned plant model system for studying natural variation and conducting gene discovery studies. Genome wide association studies (GWAS) in restructured populations combining natural and recombinant lines is a particularly effective way to identify the genetic basis of complex traits. As most abiotic stresses affect photosynthetic activity, chlorophyll fluorescence measurements are a potential phenotyping technique for monitoring plant performance under stress conditions. This review focuses on the use of chlorophyll fluorescence as a tool to study genetic variation underlying the stress tolerance responses to abiotic stress in A. thaliana.

  13. Photosynthetic system in Blastochloris viridis revisited.

    Science.gov (United States)

    Konorty, Marina; Brumfeld, Vlad; Vermeglio, Andre; Kahana, Nava; Medalia, Ohad; Minsky, Abraham

    2009-06-09

    The bacterium Blastochloris viridis carries one of the simplest photosynthetic systems, which includes a single light-harvesting complex that surrounds the reaction center, membrane soluble quinones, and a soluble periplasmic protein cytochrome c(2) that shuttle between the reaction center and the bc(1) complex and act as electron carriers, as well as the ATP synthase. The close arrangement of the photosynthetic membranes in Bl. viridis, along with the extremely tight arrangement of the photosystems within these membranes, raises a fundamental question about the diffusion of the electron carriers. To address this issue, we analyzed the structure and response of the Bl. viridis photosynthetic system to various light conditions, by using a combination of electron microscopy, whole-cell cryotomography, and spectroscopic methods. We demonstrate that in response to high light intensities, the ratio of both cytochrome c(2) and bc(1) complexes to the reaction centers is increased. The shorter membrane stacks, along with the notion that the bc(1) complex is located at the highly curved edges of these stacks, result in a smaller average distance between the reaction centers and the bc(1) complexes, leading to shorter pathways of cytochrome c(2) between the two complexes. Under anaerobic conditions, the slow diffusion rate is further mitigated by keeping most of the quinone pool reduced, resulting in a concentration gradient of quinols that allows for a constant supply of theses electron carriers to the bc(1) complex.

  14. Studies on Photosynthetic Characteristics of Plum Leaves

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Many photosynthetic characteristics of three plum varieties were studied with a infrared CO2 analyzer. Results showed that plums belong to light-loving species,having a relative high light compensation point (75~ 80μmol · m-2 · s-1 ), In natural light range from none to 1400μmol · m-2s-1PAR,the light response curve of plum as a hyperbo and the net photosynthetic rate(Pn) in leavs increased with PA elevation. Pn of plum tree was 20 to 22.50mg CO2 · dm-1 · h-1 at 1380μmol · m-2 · s-1 PAR,indicating that plum was typi cal C3-type fruit tree. Diurnal change in Pn was a bimoal curve with the highest photosynthetic rate arising at about 10:00 a. m. indicated the clear“none-rest”characteristic in plum leaves. Among three varieties. SuiLi3 had the shortest“none-rest“time followed by JiLin6 and NuXinLi. Seasonal change in Pn was a bi modal curve with the first period of high Pn in late June and the second in late August. Pn in leaves decreased visibly in period of drought in Spring and Summer.

  15. Radiative Energy Budgets of Phototrophic Surface-Associated Microbial Communities and their Photosynthetic Efficiency Under Diffuse and Collimated Light

    Science.gov (United States)

    Lichtenberg, Mads; Brodersen, Kasper E.; Kühl, Michael

    2017-01-01

    structural organization of phytoelements are important traits affecting the photosynthetic efficiency of biofilms and sediments. PMID:28400749

  16. Genes involved in the biosynthesis of photosynthetic pigments in the purple sulfur photosynthetic bacterium Thiocapsa roseopersicina.

    Science.gov (United States)

    Kovács, Akos T; Rákhely, Gábor; Kovács, Kornél L

    2003-06-01

    A pigment mutant strain of the purple sulfur photosynthetic bacterium Thiocapsa roseopersicina BBS was isolated by plasposon mutagenesis. Nineteen open reading frame, most of which are thought to be genes involved in the biosynthesis of carotenoids, bacteriochlorophyll, and the photosynthetic reaction center, were identified surrounding the plasposon in a 22-kb-long chromosomal locus. The general arrangement of the photosynthetic genes was similar to that in other purple photosynthetic bacteria; however, the locations of a few genes occurring in this region were unusual. Most of the gene products showed the highest similarity to the corresponding proteins in Rubrivivax gelatinosus. The plasposon was inserted into the crtD gene, likely inactivating crtC as well, and the carotenoid composition of the mutant strain corresponded to the aborted spirilloxanthin pathway. Homologous and heterologous complementation experiments indicated a conserved function of CrtC and CrtD in the purple photosynthetic bacteria. The crtDC and crtE genes were shown to be regulated by oxygen, and a role of CrtJ in aerobic repression was suggested.

  17. Variability of photosynthetic parameters of Pinus sibirica Du Tour needles under changing climatic factors

    Directory of Open Access Journals (Sweden)

    A.P. Zotikova

    2013-12-01

    Full Text Available The air temperature and relative humidity and the intensity of photosynthetically active radiation are the basic ecological factors determining geographical distribution of a species. Wood plant adaptation depends on the intensity of physiological and biochemicalprocesses of plants as a response to changing environmental factors. Investigations to reveal (detect the variability of modification andgenetic components of the photosynthetic parameters in needles of the Siberian cedar (Pinus sibirica Du Tour mountain ecotypes, distributed in central part of the Altai Mountains, were carried out. Also, the survey was extended to some experiments with these ecotypes introduced to mild climate and flat regions from south-western of Siberia. The length and thickness of needles, the size of chloroplasts, content of the photosynthetic pigments, and the functional activity of chloroplastsat the level of photo system II were the evaluated traits. Growing under mountainous conditions (at about 2000m elevation, the two-year-old needles were shorter and thicker and contained very large in size chloroplasts while the content of chlorophylls and carotinoids was twice lower than that in the local ecotype growing in the lowlands. On the other hand, more green and yellow pigments were found in needles of mountain ecotypes planted in the lowlands compared to the local lowland ectype trees. A decrease in pool of the photosynthetic pigments in the highlands ecotypes is probably due to decreased biosynthesis andincreased photo-destruction caused by severe light and temperature conditions. These parameters are likely to be associated withmodifications due to intense insolation, low temperature, ozone concentration, UV radiation, and other negative factors that are morepronounced at high elevation. Despite the large pool of accumulated photosynthetic pigments, the functional activity of chloroplasts in themountain ecotype at the level

  18. Variability of photosynthetic parameters of Pinus sibirica Du Tour needles under changing climatic factors

    Directory of Open Access Journals (Sweden)

    A.P. Zotikova

    2013-12-01

    Full Text Available The air temperature and relative humidity and the intensity of photosynthetically active radiation are the basic ecological factors determining geographical distribution of a species. Wood plant adaptation depends on the intensity of physiological and biochemicalprocesses of plants as a response to changing environmental factors. Investigations to reveal (detect the variability of modification andgenetic components of the photosynthetic parameters in needles of the Siberian cedar (Pinus sibirica Du Tour mountain ecotypes, distributed in central part of the Altai Mountains, were carried out. Also, the survey was extended to some experiments with these ecotypes introduced to mild climate and flat regions from south-western of Siberia. The length and thickness of needles, the size of chloroplasts, content of the photosynthetic pigments, and the functional activity of chloroplastsat the level of photo system II were the evaluated traits. Growing under mountainous conditions (at about 2000m elevation, the two-year-old needles were shorter and thicker and contained very large in size chloroplasts while the content of chlorophylls and carotinoids was twice lower than that in the local ecotype growing in the lowlands. On the other hand, more green and yellow pigments were found in needles of mountain ecotypes planted in the lowlands compared to the local lowland ectype trees. A decrease in pool of the photosynthetic pigments in the highlands ecotypes is probably due to decreased biosynthesis andincreased photo-destruction caused by severe light and temperature conditions. These parameters are likely to be associated withmodifications due to intense insolation, low temperature, ozone concentration, UV radiation, and other negative factors that are morepronounced at high elevation. Despite the large pool of accumulated photosynthetic pigments, the functional activity of chloroplasts in themountain ecotype at the level

  19. Linking hydraulic traits to tropical forest function in a size-structured and trait-driven model (TFS v.1-Hydro)

    Science.gov (United States)

    Christoffersen, Bradley O.; Gloor, Manuel; Fauset, Sophie; Fyllas, Nikolaos M.; Galbraith, David R.; Baker, Timothy R.; Kruijt, Bart; Rowland, Lucy; Fisher, Rosie A.; Binks, Oliver J.; Sevanto, Sanna; Xu, Chonggang; Jansen, Steven; Choat, Brendan; Mencuccini, Maurizio; McDowell, Nate G.; Meir, Patrick

    2016-11-01

    Forest ecosystem models based on heuristic water stress functions poorly predict tropical forest response to drought partly because they do not capture the diversity of hydraulic traits (including variation in tree size) observed in tropical forests. We developed a continuous porous media approach to modeling plant hydraulics in which all parameters of the constitutive equations are biologically interpretable and measurable plant hydraulic traits (e.g., turgor loss point πtlp, bulk elastic modulus ɛ, hydraulic capacitance Cft, xylem hydraulic conductivity ks,max, water potential at 50 % loss of conductivity for both xylem (P50,x) and stomata (P50,gs), and the leaf : sapwood area ratio Al : As). We embedded this plant hydraulics model within a trait forest simulator (TFS) that models light environments of individual trees and their upper boundary conditions (transpiration), as well as providing a means for parameterizing variation in hydraulic traits among individuals. We synthesized literature and existing databases to parameterize all hydraulic traits as a function of stem and leaf traits, including wood density (WD), leaf mass per area (LMA), and photosynthetic capacity (Amax), and evaluated the coupled model (called TFS v.1-Hydro) predictions, against observed diurnal and seasonal variability in stem and leaf water potential as well as stand-scaled sap flux. Our hydraulic trait synthesis revealed coordination among leaf and xylem hydraulic traits and statistically significant relationships of most hydraulic traits with more easily measured plant traits. Using the most informative empirical trait-trait relationships derived from this synthesis, TFS v.1-Hydro successfully captured individual variation in leaf and stem water potential due to increasing tree size and light environment, with model representation of hydraulic architecture and plant traits exerting primary and secondary controls, respectively, on the fidelity of model predictions. The plant

  20. FishTraits Database

    Science.gov (United States)

    Angermeier, Paul L.; Frimpong, Emmanuel A.

    2009-01-01

    The need for integrated and widely accessible sources of species traits data to facilitate studies of ecology, conservation, and management has motivated development of traits databases for various taxa. In spite of the increasing number of traits-based analyses of freshwater fishes in the United States, no consolidated database of traits of this group exists publicly, and much useful information on these species is documented only in obscure sources. The largely inaccessible and unconsolidated traits information makes large-scale analysis involving many fishes and/or traits particularly challenging. FishTraits is a database of >100 traits for 809 (731 native and 78 exotic) fish species found in freshwaters of the conterminous United States, including 37 native families and 145 native genera. The database contains information on four major categories of traits: (1) trophic ecology, (2) body size and reproductive ecology (life history), (3) habitat associations, and (4) salinity and temperature tolerances. Information on geographic distribution and conservation status is also included. Together, we refer to the traits, distribution, and conservation status information as attributes. Descriptions of attributes are available here. Many sources were consulted to compile attributes, including state and regional species accounts and other databases.

  1. Clinicopathological correlation of acquired hyperpigmentary disorders

    Directory of Open Access Journals (Sweden)

    Anisha B Patel

    2013-01-01

    Full Text Available Acquired pigmentary disorders are group of heterogenous entities that share single, most significant, clinical feature, that is, dyspigmentation. Asians and Indians, in particular, are mostly affected. Although the classic morphologies and common treatment options of these conditions have been reviewed in the global dermatology literature, the value of histpathological evaluation has not been thoroughly explored. The importance of accurate diagnosis is emphasized here as the underlying diseases have varying etiologies that need to be addressed in order to effectively treat the dyspigmentation. In this review, we describe and discuss the utility of histology in the diagnostic work of hyperpigmentary disorders, and how, in many cases, it can lead to targeted and more effective therapy. We focus on the most common acquired pigmentary disorders seen in Indian patients as well as a few uncommon diseases with distinctive histological traits. Facial melanoses, including mimickers of melasma, are thoroughly explored. These diseases include lichen planus pigmentosus, discoid lupus erythematosus, drug-induced melanoses, hyperpigmentation due to exogenous substances, acanthosis nigricans, and macular amyloidosis.

  2. 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.

  3. Communication: Coherences observed in vivo in photosynthetic bacteria using two-dimensional electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dahlberg, Peter D. [Graduate Program in the Biophysical Sciences, Institute for Biophysical Dynamics, and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Norris, Graham J.; Wang, Cheng; Viswanathan, Subha; Singh, Ved P.; Engel, Gregory S., E-mail: gsengel@uchicago.edu [Department of Chemistry, Institute for Biophysical Dynamics, and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States)

    2015-09-14

    Energy transfer through large disordered antenna networks in photosynthetic organisms can occur with a quantum efficiency of nearly 100%. This energy transfer is facilitated by the electronic structure of the photosynthetic antennae as well as interactions between electronic states and the surrounding environment. Coherences in time-domain spectroscopy provide a fine probe of how a system interacts with its surroundings. In two-dimensional electronic spectroscopy, coherences can appear on both the ground and excited state surfaces revealing detailed information regarding electronic structure, system-bath coupling, energy transfer, and energetic coupling in complex chemical systems. Numerous studies have revealed coherences in isolated photosynthetic pigment-protein complexes, but these coherences have not been observed in vivo due to the small amplitude of these signals and the intense scatter from whole cells. Here, we present data acquired using ultrafast video-acquisition gradient-assisted photon echo spectroscopy to observe quantum beating signals from coherences in vivo. Experiments were conducted on isolated light harvesting complex II (LH2) from Rhodobacter sphaeroides, whole cells of R. sphaeroides, and whole cells of R. sphaeroides grown in 30% deuterated media. A vibronic coherence was observed following laser excitation at ambient temperature between the B850 and the B850{sup ∗} states of LH2 in each of the 3 samples with a lifetime of ∼40-60 fs.

  4. Communication: Coherences observed in vivo in photosynthetic bacteria using two-dimensional electronic spectroscopy

    Science.gov (United States)

    Dahlberg, Peter D.; Norris, Graham J.; Wang, Cheng; Viswanathan, Subha; Singh, Ved P.; Engel, Gregory S.

    2015-01-01

    Energy transfer through large disordered antenna networks in photosynthetic organisms can occur with a quantum efficiency of nearly 100%. This energy transfer is facilitated by the electronic structure of the photosynthetic antennae as well as interactions between electronic states and the surrounding environment. Coherences in time-domain spectroscopy provide a fine probe of how a system interacts with its surroundings. In two-dimensional electronic spectroscopy, coherences can appear on both the ground and excited state surfaces revealing detailed information regarding electronic structure, system-bath coupling, energy transfer, and energetic coupling in complex chemical systems. Numerous studies have revealed coherences in isolated photosynthetic pigment-protein complexes, but these coherences have not been observed in vivo due to the small amplitude of these signals and the intense scatter from whole cells. Here, we present data acquired using ultrafast video-acquisition gradient-assisted photon echo spectroscopy to observe quantum beating signals from coherences in vivo. Experiments were conducted on isolated light harvesting complex II (LH2) from Rhodobacter sphaeroides, whole cells of R. sphaeroides, and whole cells of R. sphaeroides grown in 30% deuterated media. A vibronic coherence was observed following laser excitation at ambient temperature between the B850 and the B850∗ states of LH2 in each of the 3 samples with a lifetime of ∼40-60 fs. PMID:26373989

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

    Directory of Open Access Journals (Sweden)

    Celio Helder Resende de Sousa

    2017-01-01

    Full Text Available 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 (ε at four sites in the Amazon Basin: r2 values ranged from 0.37 to 0.51 for northern flux sites and to 0.78 for 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.

  6. Multidimensional Ultrafast Spectroscopy of Photosynthetic Pigment-Protein Complexes

    OpenAIRE

    De Re, Eleonora

    2014-01-01

    This dissertation presents the application of ultrafast spectroscopy to the investigation of pigment-protein complexes (PPCs) involved in energy transfer and energy dissipation in photosynthetic organisms. PPCs are the building blocks of all photosynthetic organisms, and within individual pigment-protein complexes, energy transfer dynamics occur over fast timescales and broad spectral regions. Chapter 1 gives an introduction to the capability of photosynthetic organisms to absorb light energy...

  7. Multiscale Analysis and Optimisation of Photosynthetic Solar Energy Systems

    CERN Document Server

    Ringsmuth, Andrew K

    2014-01-01

    This work asks how light harvesting in photosynthetic systems can be optimised for economically scalable, sustainable energy production. Hierarchy theory is introduced as a system-analysis and optimisation tool better able to handle multiscale, multiprocess complexities in photosynthetic energetics compared with standard linear-process analysis. Within this framework, new insights are given into relationships between composition, structure and energetics at the scale of the thylakoid membrane, and also into how components at different scales cooperate under functional objectives of the whole photosynthetic system. Combining these reductionistic and holistic analyses creates a platform for modelling multiscale-optimal, idealised photosynthetic systems in silico.

  8. Modulation of Leaf Economic Traits and Rates by Soil Properties, at Global Scale

    Science.gov (United States)

    Maire, V.; Wright, I. J.; Reich, P. B.; Batjes, N. H., Jr.; van Bodegom, P. M.; Bhaskar, R.; Santiago, L. S.; Ellsworth, D.; Niinemets, U.; Cornwell, W.

    2014-12-01

    Photosynthesis can be construed as an economic process that optimises the costs of acquisition, transport and utilisation of two substitutable photosynthetic resources: water and nitrogen. The influence of soil fertility on photosynthetic rates and leaf 'economic' traits related with H2O and N costs is poorly quantified in higher plants in comparison with the effects of climate. We set out to address this situation by quantifying the unique and shared contributions to global leaf-trait variation from soils and climate. Using a trait dataset comprising 1509 species from 288 sites, with climate and soil data derived from global datasets, we quantified the effects of soil and climate properties on photosynthetic traits: light-saturated photosynthetic rate (Aarea), stomatal conductance to water vapour (gs), leaf N and P (Narea and Parea) and specific leaf area (SLA). We used mixed regression models, multivariate analyses and variance partitioning. Along a first dimension of soil fertility, soil pH covaried positively with measures of base status and climatic aridity, and negatively with soil organic C content. Along this dimension from low to high soil pH, Narea, Parea and Aarea increased and SLA decreased. Along an independent dimension of soil fertility, gs declined and Parea increased with soil available P (Pavail). Overall, soil variables were stronger predictors of leaf traits than were climate variables, except for SLA. Importantly, soils and climate were not redundant information to explain leaf trait variation but were not additive either. Shared effects of soil and climate dominated over their independent effects on Narea and Parea, while unique effects of soils dominated for Aarea and gs. Three environmental variables were key for explaining variation in leaf traits: soil pH and Pavail, and climatic aridity. Although the reliability of global soils datasets lags behind that of climate datasets our results nonetheless provide compelling evidence that both can

  9. Microspectroscopy of the photosynthetic compartment of algae.

    Science.gov (United States)

    Evangelista, Valtere; Frassanito, Anna Maria; Passarelli, Vincenzo; Barsanti, Laura; Gualtieri, Paolo

    2006-01-01

    We performed microspectroscopic evaluation of the pigment composition of the photosynthetic compartments of algae belonging to different taxonomic divisions and higher plants. The feasibility of microspectroscopy for discriminating among species and/or phylogenetic groups was tested on laboratory cultures. Gaussian bands decompositions and a fitting algorithm, together with fourth-derivative transformation of absorbance spectra, provided a reliable discrimination among chlorophylls a, b and c, phycobiliproteins and carotenoids. Comparative analysis of absorption spectra highlighted the evolutionary grouping of the algae into three main lineages in accordance with the most recent endosymbiotic theories.

  10. Culturing photosynthetic bacteria through surface plasmon resonance

    Science.gov (United States)

    Ooms, Matthew D.; Bajin, Lauren; Sinton, David

    2012-12-01

    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 μm 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.

  11. Simulation of photosynthetic production using neural network

    Science.gov (United States)

    Kmet, Tibor; Kmetova, Maria

    2013-10-01

    This paper deals with neural network based optimal control synthesis for solving optimal control problems with control and state constraints and discrete time delay. The optimal control problem is transcribed into nonlinear programming problem which is implemented with adaptive critic neural network. This approach is applicable to a wide class of nonlinear systems. The proposed simulation methods is illustrated by the optimal control problem of photosynthetic production described by discrete time delay differential equations. Results show that adaptive critic based systematic approach holds promise for obtaining the optimal control with control and state constraints.

  12. 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.

  13. Comparisons of photosynthesis-related traits of 27 abundant or subordinate bryophyte species in a subalpine old-growth fir forest.

    Science.gov (United States)

    Wang, Zhe; Bader, Maaike Y; Liu, Xin; Zhu, Zhangming; Bao, Weikai

    2017-09-01

    Bryophyte communities can exhibit similar structural and taxonomic diversity as vascular plant communities, just at a smaller scale. Whether the physiological diversity can be similarly diverse, and whether it can explain local abundance patterns is unknown, due to a lack of community-wide studies of physiological traits. This study re-analyzed data on photosynthesis-related traits (including the nitrogen, phosphorus and chlorophyll concentrations, photosynthetic capacities, and photosynthetic nutrient use efficiencies) of 27 bryophyte species in a subalpine old-growth fir forest on the eastern Tibetan Plateau. We explored differences between taxonomic groups and hypothesized that the most abundant bryophyte species had physiological advantages relative to other subdominant species. Principal component analysis (PCA) was used to summarize the differences among species and trait values of the most abundant and other co-occurring subdominant species. Species from the Polytrichaceae were separated out on both PCA axes, indicating their high chlorophyll concentrations and photosynthetic capacities (axis 1) and relatively high-light requirements (axis 2). Mniaceae species also had relatively high photosynthetic capacities, but their light saturation points were low. In contrast, Racomitrium joseph-hookeri and Lepidozia reptans, two species with a high shoot mass per area, had high-light requirements and low nutrient and chlorophyll concentrations and photosynthetic capacities. The nutrient concentrations, photosynthetic capacities, and photosynthetic nutrient use efficiencies of the most abundant bryophyte species did not differ from co-occurring subdominant species. Our research confirms the links between the photosynthesis-related traits and adaptation strategies of bryophytes. However, species relative abundance was not related to these traits.

  14. Sickle Cell Trait

    Science.gov (United States)

    ... Websites About Us Information For… Media Policy Makers Sickle Cell Trait Language: English (US) Español (Spanish) Recommend on Facebook Tweet Share Compartir Get Screened for Sickle Cell Trait Did you know there’s more than one way ...

  15. Wide ranges of functional traits in the flora from the central region of Sonora: A diversity to be explored

    Science.gov (United States)

    Cesar Hinojo Hinojo; Alejandro E. Castellanos; Jose M. Llano. Sotelo

    2013-01-01

    Although the Sonoran Desert does not have the highest plant species richness, it has been documented with the highest growth form diversity from the North American deserts. It is not known if this high growth form diversity could also harbor a high functional diversity. In this study we characterize the ecophysiological functional traits of photosynthetic capacity,...

  16. QTL analysis of leaf photosynthesis rate and related physiological traits in Brassica napus

    Institute of Scientific and Technical Information of China (English)

    YAN Xing-ying; QU Cun-min; LI Jia-na; CHEN Li; LIU Lie-zhao

    2015-01-01

    Rapeseed (Brassica napus L.) oil is the crucial source of edible oil in China. In addition, it can become a major renewable and sustainable feedstock for biodiesel production in the future. It is known that photosynthesis products are the primary sources for dry matter accumulation in rapeseed. Therefore, increasing the photosynthetic efifciency is desirable for the raise of rapeseed yield. The objective of the present study was to identify the genetic mechanism of photosynthesis based on the description of relationships between different photosynthetic traits and their quantitative trait loci (QTL) by using a recombinant inbred line (RIL) population with 172 lines. Speciifcal y, correlation analysis in this study showed that internal CO2 concentration has negative correlations with other three physiological traits under two different stages. Total y, 11 and 12 QTLs of the four physiological traits measured at the stages 1 and 2 were detected by using a high-density single nu-cleotidepolymorphism (SNP) markers linkage map with composite interval mapping (CIM), respectively. Three co-localized QTLs on A03 were detected at stage 1 with 5, 5, and 10%of the phenotypic variation, respectively. Other two co-localized QTLs were located on A05 at stage 2, which explained up to 12 and 5%of the phenotypic variation, respectively. The results are beneifcial for our understanding of genetic control of photosynthetic physiological characterizations and improvement of rapeseed yield in the future.

  17. Acquired ichthyosis with hoffman's syndrome

    Directory of Open Access Journals (Sweden)

    Sathyanarayana B

    2003-01-01

    Full Text Available A middle aged man presented with features of acquired ichthyosis with Hoffman's syndrome. Laboratory tests support hypothyodism. Myoedema and hypertrophy of muscles were present. Patient was previously treated for Pellagra.

  18. Generality of leaf trait relationships: A test across six biomes

    Energy Technology Data Exchange (ETDEWEB)

    Reich, P.B. [Univ. of Minnesota, Saint Paul, MN (United States). Dept. of Forest Resources; Ellsworth, D.S. [Brookhaven National Lab., Upton, NY (United States). Dept. of Applied Science; Walters, M.B. [Michigan State Univ., East Lansing, MI (United States). Dept. of Forestry; Vose, J.M. [Forest Service, Otto, NC (United States). Coweeta Hydrological Lab.; Gresham, C. [Clemson Univ., Georgetown, SC (United States). Baruch Forest Inst.; Volin, J.C. [Florida Atlantic Univ., Davie, FL (United States). Div. of Science; Bowman, W.D. [Inst. of Arctic and Alpine Research, Boulder, CO (United States). Mountain Research Station]|[Univ. of Colorado, Boulder, CO (United States). Dept. of Evolutionary, Population, and Organismic Biology

    1999-09-01

    Convergence in interspecific leaf trait relationships across diverse taxonomic groups and biomes would have important evolutionary and ecological implications. Such convergence has been hypothesized to result from trade-offs that limit the combination of plant traits for any species. Here the authors address this issue by testing for biome differences in the slope and intercept of interspecific relationships among leaf traits: longevity, net photosynthetic capacity (A{sub max}), leaf diffusive conductance (G{sub S}), specific leaf area (SLA), and nitrogen (N) status, for more than 100 species in six distinct biomes of the Americas. The six biomes were: alpine tundra-subalpine forest ecotone, cold temperate forest-prairie ecotone, montane cool temperate forest, desert shrubland, subtropical forest, and tropical rain forest. Despite large differences in climate and evolutionary history, in all biomes mass-based leaf N (N{sub mass}), SLA, G{sub S}, and A{sub max} were positively related to one another and decreased with increasing leaf life span. The relationships between pairs of leaf traits exhibited similar slopes among biomes, suggesting a predictable set of scaling relationships among key leaf morphological, chemical, and metabolic traits that are replicated globally among terrestrial ecosystems regardless of biome or vegetation type. However, the intercept (i.e., the overall elevation of regression lines) of relationships between pairs of leaf traits usually differed among biomes. With increasing aridity across sites, species had greater A{sub max} for a given level of G{sub S} and lower SLA for any given leaf life span. Using principal components analysis, most variation among species was explained by an axis related to mass-based leaf traits (A{sub max}, N, and SLA) while a second axis reflected climate, G{sub S}, and other area-based leaf traits.

  19. 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.

  20. Non-photosynthetic pigments as potential biosignatures

    Science.gov (United States)

    Schwieterman, E. W.; Cockell, C. S.; Meadows, V. S.

    2014-03-01

    Photosynthetic organisms on Earth produce potentially detectable surface reflectance biosignatures due in part to the spectral location and strength of pigment absorption. However, life on Earth uses pigments for a multitude of purposes other than photosynthesis, including coping with extreme environments. Macroscopic environments exist on Earth where the surface reflectance is significantly altered by a nonphotosynthetic pigment, such as the case of hypersaline lakes and ponds (Oren et al. 1992). Here we explore the nature and potential detectability of non-photosynthetic pigments in disk-averaged planetary observations using a combination of laboratory measurements and archival reflectance spectra, along with simulated broadband photometry and spectra. The in vivo visible reflectance spectra of a cross section of pigmented microorganisms are presented to illustrate the spectral diversity of biologically produced pigments. Synthetic broadband colors are generated to show a significant spread in color space. A 1D radiative transfer model (Meadows & Crisp 1996; Crisp 1997) is used to approximate the spectra of scenarios where pigmented organisms are widespread on planets with Earth-like atmospheres. Broadband colors are revisited to show that colors due to surface reflectivity are not robust to the addition of scattering and absorption effects from the atmosphere. We consider a èbest case' plausible scenario for the detection of nonphotosynthetic pigments by using the Virtual Planetary Laboratory's 3D spectral Earth model (Robinson et al. 2011) to explore the detectability of the surface biosignature produced by pigmented halophiles that are widespread on an Earth-analog planet.

  1. Engineered photosynthetic bacteria, method of manufacture of biofuels

    Energy Technology Data Exchange (ETDEWEB)

    Laible, Philip D.; Snyder, Seth W.

    2016-09-13

    The invention provides for a novel type of biofuel; a method for cleaving anchors from photosynthetic organisms; and a method for producing biofuels using photosynthetic organisms, the method comprising identifying photosynthesis co-factors and their anchors in the organisms; modifying the organisms to increase production of the anchors; accumulating biomass of the organisms in growth media; and harvesting the anchors.

  2. Somatically acquired structural genetic differences

    DEFF Research Database (Denmark)

    Magaard Koldby, Kristina; Nygaard, Marianne; Christensen, Kaare;

    2016-01-01

    Structural genetic variants like copy number variants (CNVs) comprise a large part of human genetic variation and may be inherited as well as somatically acquired. Recent studies have reported the presence of somatically acquired structural variants in the human genome and it has been suggested t...... with age.European Journal of Human Genetics advance online publication, 20 April 2016; doi:10.1038/ejhg.2016.34.......Structural genetic variants like copy number variants (CNVs) comprise a large part of human genetic variation and may be inherited as well as somatically acquired. Recent studies have reported the presence of somatically acquired structural variants in the human genome and it has been suggested...... that they may accumulate in elderly individuals. To further explore the presence and the age-related acquisition of somatic structural variants in the human genome, we investigated CNVs acquired over a period of 10 years in 86 elderly Danish twins as well as CNV discordances between co-twins of 18 monozygotic...

  3. 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

  4. Antenna organization in green photosynthetic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Blankenship, R.E.

    1987-01-01

    This project is concerned with the structure and function of the unique antenna system found in the green photosynthetic bacteria. The antenna system in these organisms is contained within a vesicle known as a chlorosome, which is attached to the cytoplasmic side of the cell membrane. Additional antenna pigments and reaction centers are contained in integral membrane proteins. Energy absorbed by the bacteriochlorophyll c (BChl c) pigments in the chlorosome is transferred via a baseplate'' array of BChl a antenna pigments into the membrane and to the reaction center. A schematic model of chlorosome structure is shown. This project is aimed at increasing our understanding of the organization of the pigments in the chlorosome and how the antenna system functions.

  5. Photosynthetic machineries in nano-systems.

    Science.gov (United States)

    Nagy, László; Magyar, Melinda; Szabó, Tibor; Hajdu, Kata; Giotta, Livia; Dorogi, Márta; Milano, Francesco

    2014-01-01

    Photosynthetic reaction centres are membrane-spanning proteins, found in several classes of autotroph organisms, where a photoinduced charge separation and stabilization takes place with a quantum efficiency close to unity. The protein remains stable and fully functional also when extracted and purified in detergents thereby biotechnological applications are possible, for example, assembling it in nano-structures or in optoelectronic systems. Several types of bionanocomposite materials have been assembled by using reaction centres and different carrier matrices for different purposes in the field of light energy conversion (e.g., photovoltaics) or biosensing (e.g., for specific detection of pesticides). In this review we will summarize the current status of knowledge, the kinds of applications available and the difficulties to be overcome in the different applications. We will also show possible research directions for the close future in this specific field.

  6. Elementary Energy Transfer Pathways in Allochromatium vinosum Photosynthetic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Lüer, Larry; Carey, Anne-Marie; Henry, Sarah; Maiuri, Margherita; Hacking, Kirsty; Polli, Dario; Cerullo, Giulio; Cogdell, Richard J.

    2015-11-01

    Allochromatium vinosum (formerly Chromatium vinosum) purple bacteria are known to adapt their light-harvesting strategy during growth according to environmental factors such as temperature and average light intensity. Under low light illumination or low ambient temperature conditions, most of the LH2 complexes in the photosynthetic membranes form a B820 exciton with reduced spectral overlap with LH1. To elucidate the reason for this light and temperature adaptation of the LH2 electronic structure, we performed broadband femtosecond transient absorption spectroscopy as a function of excitation wavelength in A. vinosum membranes. A target analysis of the acquired data yielded individual rate constants for all relevant elementary energy transfer (ET) processes. We found that the ET dynamics in high-light-grown membranes was well described by a homogeneous model, with forward and backward rate constants independent of the pump wavelength. Thus, the overall B800→B850→B890→ Reaction Center ET cascade is well described by simple triexponential kinetics. In the low-light-grown membranes, we found that the elementary backward transfer rate constant from B890 to B820 was strongly reduced compared with the corresponding constant from B890 to B850 in high-light-grown samples. The ET dynamics of low-light-grown membranes was strongly dependent on the pump wavelength, clearly showing that the excitation memory is not lost throughout the exciton lifetime. The observed pump energy dependence of the forward and backward ET rate constants suggests exciton diffusion via B850→ B850 transfer steps, making the overall ET dynamics nonexponential. Our results show that disorder plays a crucial role in our understanding of low-light adaptation in A. vinosum.

  7. Elementary Energy Transfer Pathways in Allochromatium vinosum Photosynthetic Membranes.

    Science.gov (United States)

    Lüer, Larry; Carey, Anne-Marie; Henry, Sarah; Maiuri, Margherita; Hacking, Kirsty; Polli, Dario; Cerullo, Giulio; Cogdell, Richard J

    2015-11-01

    Allochromatium vinosum (formerly Chromatium vinosum) purple bacteria are known to adapt their light-harvesting strategy during growth according to environmental factors such as temperature and average light intensity. Under low light illumination or low ambient temperature conditions, most of the LH2 complexes in the photosynthetic membranes form a B820 exciton with reduced spectral overlap with LH1. To elucidate the reason for this light and temperature adaptation of the LH2 electronic structure, we performed broadband femtosecond transient absorption spectroscopy as a function of excitation wavelength in A. vinosum membranes. A target analysis of the acquired data yielded individual rate constants for all relevant elementary energy transfer (ET) processes. We found that the ET dynamics in high-light-grown membranes was well described by a homogeneous model, with forward and backward rate constants independent of the pump wavelength. Thus, the overall B800→B850→B890→ Reaction Center ET cascade is well described by simple triexponential kinetics. In the low-light-grown membranes, we found that the elementary backward transfer rate constant from B890 to B820 was strongly reduced compared with the corresponding constant from B890 to B850 in high-light-grown samples. The ET dynamics of low-light-grown membranes was strongly dependent on the pump wavelength, clearly showing that the excitation memory is not lost throughout the exciton lifetime. The observed pump energy dependence of the forward and backward ET rate constants suggests exciton diffusion via B850→ B850 transfer steps, making the overall ET dynamics nonexponential. Our results show that disorder plays a crucial role in our understanding of low-light adaptation in A. vinosum.

  8. Photosynthetic reaction centers/ITO hybrid nanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Szabo, Tibor [Department of Medical Physics and Informatics, University of Szeged, Szeged (Hungary); Bencsik, Gabor [Department of Physical Chemistry and Materials Science, University of Szeged, Szeged (Hungary); Magyar, Melinda [Department of Medical Physics and Informatics, University of Szeged, Szeged (Hungary); Visy, Csaba [Department of Physical Chemistry and Materials Science, University of Szeged, Szeged (Hungary); Gingl, Zoltan [Department of Technical Informatics, University of Szeged, Szeged (Hungary); Nagy, Krisztina; Varo, Gyoergy [Institute of Biophysics, Hungarian Academy of Sciences, Biological Research Center, Szeged (Hungary); Hajdu, Kata; Kozak, Gabor [Department of Medical Physics and Informatics, University of Szeged, Szeged (Hungary); Nagy, Laszlo, E-mail: lnagy@sol.cc.u-szeged.hu [Department of Medical Physics and Informatics, University of Szeged, Szeged (Hungary)

    2013-03-01

    Photosynthetic reaction center proteins purified from Rhodobacter sphaeroides purple bacterium were deposited on the surface of indium tin oxide (ITO), a transparent conductive oxide, and the photochemical/-physical properties of the composite were investigated. The kinetics of the light induced absorption change indicated that the RC was active in the composite and there was an interaction between the protein cofactors and the ITO. The electrochromic response of the bacteriopheophytine absorption at 771 nm showed an increased electric field perturbation around this chromophore on the surface of ITO compared to the one measured in solution. This absorption change is associated with the charge-compensating relaxation events inside the protein. Similar life time, but smaller magnitude of this absorption change was measured on the surface of borosilicate glass. The light induced change in the conductivity of the composite as a function of the concentration showed the typical sigmoid saturation characteristics unlike if the photochemically inactive chlorophyll was layered on the ITO. In this later case the light induced change in the conductivity was oppositely proportional to the chlorophyll concentration due to the thermal dissipation of the excitation energy. The sensitivity of the measurement is very high; few picomole RC can change the light induced resistance of the composite. - Highlights: Black-Right-Pointing-Pointer Photosynthetic reaction center/ITO nanocomposite has been fabricated. Black-Right-Pointing-Pointer The composite showed photochemical/-physical activity with very high sensitivity. Black-Right-Pointing-Pointer This new type of material can be a good model of optoelectronic devices.

  9. Multivariate Analysis of Grain Yield and Its Attributing Traits in Different Maize Hybrids Grown under Heat and Drought Stress.

    Science.gov (United States)

    Ali, Fawad; Kanwal, Naila; Ahsan, Muhammmad; Ali, Qurban; Bibi, Irshad; Niazi, Nabeel Khan

    2015-01-01

    This study was carried out to evaluate F1 single cross-maize hybrids in four crop growing seasons (2010-2012). Morphological traits and physiological parameters of twelve maize hybrids were evaluated (i) to construct seed yield equation and (ii) to determine grain yield attributing traits of well-performing maize genotype using a previously unexplored method of two-way hierarchical clustering. In seed yield predicting equation photosynthetic rate contributed the highest variation (46%). Principal component analysis data showed that investigated traits contributed up to 90.55% variation in dependent structure. From factor analysis, we found that factor 1 contributed 49.6% variation (P < 0.05) with primary important traits (i.e., number of leaves per plant, plant height, stem diameter, fresh leaves weight, leaf area, stomata conductance, substomata CO2 absorption rate, and photosynthetic rate). The results of two-way hierarchical clustering demonstrated that Cluster III had outperforming genotype H12 (Sultan × Soneri) along with its most closely related traits (photosynthetic rate, stomata conductance, substomata CO2 absorption rate, chlorophyll contents, leaf area, and fresh stem weight). Our data shows that H12 (Sultan × Soneri) possessed the highest grain yield per plant under environmentally stress conditions, which are most likely to exist in arid and semiarid climatic conditions, such as in Pakistan.

  10. Photosynthetic efficiency in rhizophoracean mangroves with reference to compartmentalization of photosynthetic pigments

    Directory of Open Access Journals (Sweden)

    P. Moorthy

    1999-06-01

    Full Text Available Photosynthetic pigments are localized in protein complexes of chloroplast membranes and their role in photosynthesis has long been established but their efficiency has not been measured in many species. The photosynthetic efficiency of four rhizophoracean mangroves, Rhizophora apiculata, R. mucronata, Bruguiera cylindrica and Ceriops decandra was studied in randomly collected propagules from Pichavaram mangrove forest (southeast coast of India by estimating the concentration of photosynthetic pigments in protein complexes of the thylakoid membrane. Reaction centre chlorophyll (RC-chl was maximum in B. cylindrica and minimum in R. mucronata. Of the total amount of chlorophylls, RC-chl constitutes about 50%. The light harvesting complex chlorophyll (LHC-chl was highest in C. decandra and lowest in R. mucronata. Net photosynthesis was found to be higher in B. cylindrica and lower in R. mucronata with the respective CO2 fixation of 20.52 and 10.83 m mol m-2 s-1. A positive correlation was obtained between RC-chl and net photosynthesis. The stomatal conductance to CO2 influx was also found to be high and low in B. cylindrica and R. mucronata respectively. We refer the chlorophylls present in the reaction centre and light harvesting complex as " membrane bound chlorophyll" and propose to use this as an index for measuring the productivity of mangrove species.

  11. Increased grain yield with improved photosynthetic characters in modern maize parental lines

    Institute of Scientific and Technical Information of China (English)

    LI Cong-feng; TAO Zhi-qiang; LIU Peng; ZHANG Ji-wang; ZHUANG Ke-zhang; DONG Shu-ting; ZHAO Ming

    2015-01-01

    The grain yield of maize has increased continuously in past decades, largely through hybrid innovation, cultivation tech-nology, and in particular, recent genetic improvements in photosynthesis. Elite inbred lines are crucial for innovating new germplasm. Here, we analyzed variations in grain yield and a series of eco-physiological photosynthetic traits after anthesis in sixteen parental lines of maize (Zea mays L.) released during three different eras (1960s, 1980s, 2000s). We found that grain yield and biomass signiifcantly increased in the 2000s than those in the 1980s and 1960s. Leaf area, chlorophyl , and soluble protein content slowly decreased, and maintained a higher net photosynthesis rate (Pn) and improved stomatal conductance (Gs) after anthesis in the 2000s. In addition, the parental lines in the 2000s obtained higher actual photo-chemistry efifciency (ФPSI ) and the maximum PSII photochemistry efifciency (Fv/Fm), which largely improved light partition-ing and chlorophyl lfuorescence characteristic, including higher photochemical and photosystem II (PSII) reaction center activity, lower thermal energy dissipation in antenna proteins. Meanwhile, more lamel ae per granum within chloroplasts were observed in the parental lines of the 2000s, with a clear and complete chloroplast membrane, which wil greatly help to improve photosynthetic capacity and energy efifciency of ear leaf in maize parental lines. It is concluded that grain yield increase in modern maize parental lines is mainly attributed to the improved chloroplast structure and more light energy catched for the photochemical reaction, thus having a better stay-green characteristic and stronger photosynthetic capac-ity after anthesis. Our direct physiological evaluation of these inbred lines provides important information for the further development of promising maize cultivars.

  12. Increased grain yield with improved photosynthetic characters in modern maize parental lines

    Institute of Scientific and Technical Information of China (English)

    LI Cong-feng[1; TAO Zhi-qiang[1; LIU Peng[2; ZHANG Ji-wang[2; ZHUANG Ke-zhang[3; DONG Shu-ting[2; ZHAO Ming[1

    2015-01-01

    The grain yield of maize has increased continuously in past decades, largely through hybrid innovation, cultivation tech- nology, and in particular, recent genetic improvements in photosynthesis. Elite inbred lines are crucial for innovating new germplasm. Here, we analyzed variations in grain yield and a series of eco-physiological photosynthetic traits after anthesis in sixteen parental lines of maize (Zea mays L.) released during three different eras (1960s, 1980s, 2000s). We found that grain yield and biomass significantly increased in the 2000s than those in the 1980s and 1960s. Leaf area, chlorophyll, and soluble protein content slowly decreased, and maintained a higher net photosynthesis rate (Po) and improved stomatal conductance (Gs) after anthesis in the 2000s. In addition, the parental lines in the 2000s obtained higher actual photo- chemistry efficiency (Ps,) and the maximum PSII photochemistry efficiency (FJFm), which largely improved light partition- ing and chlorophyll fluorescence characteristic, including higher photochemical and photosystem II (PSII) reaction center activity, lower thermal energy dissipation in antenna proteins. Meanwhile, more lamellae per granum within chloroplasts were observed in the parental lines of the 2000s, with a clear and complete chloroplast membrane, which will greatly help to improve photosynthetic capacity and energy efficiency of ear leaf in maize parental lines. It is concluded that grain yield increase in modern maize parental lines is mainly attributed to the improved chloroplast structure and more light energy catched for the photochemical reaction, thus having a better stay-green characteristic and stronger photosynthetic capac- ity after anthesis. Our direct physiological evaluation of these inbred lines provides important information for the further development of promising maize cultivars.

  13. Effects of nutrient addition on leaf chemistry, morphology, and photosynthetic capacity of three bog shrubs.

    Science.gov (United States)

    Bubier, Jill L; Smith, Rose; Juutinen, Sari; Moore, Tim R; Minocha, Rakesh; Long, Stephanie; Minocha, Subhash

    2011-10-01

    Plants in nutrient-poor environments typically have low foliar nitrogen (N) concentrations, long-lived tissues with leaf traits designed to use nutrients efficiently, and low rates of photosynthesis. We postulated that increasing N availability due to atmospheric deposition would increase photosynthetic capacity, foliar N, and specific leaf area (SLA) of bog shrubs. We measured photosynthesis, foliar chemistry and leaf morphology in three ericaceous shrubs (Vaccinium myrtilloides, Ledum groenlandicum and Chamaedaphne calyculata) in a long-term fertilization experiment at Mer Bleue bog, Ontario, Canada, with a background deposition of 0.8 g N m(-2) a(-1). While biomass and chlorophyll concentrations increased in the highest nutrient treatment for C. calyculata, we found no change in the rates of light-saturated photosynthesis (A(max)), carboxylation (V(cmax)), or SLA with nutrient (N with and without PK) addition, with the exception of a weak positive correlation between foliar N and A(max) for C. calyculata, and higher V(cmax) in L. groenlandicum with low nutrient addition. We found negative correlations between photosynthetic N use efficiency (PNUE) and foliar N, accompanied by a species-specific increase in one or more amino acids, which may be a sign of excess N availability and/or a mechanism to reduce ammonium (NH(4)) toxicity. We also observed a decrease in foliar soluble Ca and Mg concentrations, essential minerals for plant growth, but no change in polyamines, indicators of physiological stress under conditions of high N accumulation. These results suggest that plants adapted to low-nutrient environments do not shift their resource allocation to photosynthetic processes, even after reaching N sufficiency, but instead store the excess N in organic compounds for future use. In the long term, bog species may not be able to take advantage of elevated nutrients, resulting in them being replaced by species that are better adapted to a higher nutrient environment.

  14. Same Traits, Different Variance

    Directory of Open Access Journals (Sweden)

    Jamie S. Churchyard

    2014-02-01

    Full Text Available Personality trait questionnaires are regularly used in individual differences research to examine personality scores between participants, although trait researchers tend to place little value on intra-individual variation in item ratings within a measured trait. The few studies that examine variability indices have not considered how they are related to a selection of psychological outcomes, so we recruited 160 participants (age M = 24.16, SD = 9.54 who completed the IPIP-HEXACO personality questionnaire and several outcome measures. Heterogenous within-subject differences in item ratings were found for every trait/facet measured, with measurement error that remained stable across the questionnaire. Within-subject standard deviations, calculated as measures of individual variation in specific item ratings within a trait/facet, were related to outcomes including life satisfaction and depression. This suggests these indices represent valid constructs of variability, and that researchers administering behavior statement trait questionnaires with outcome measures should also apply item-level variability indices.

  15. Photosynthetic acclimation to enriched CO{sub 2} concentrations in Pinus Ponderosa

    Energy Technology Data Exchange (ETDEWEB)

    Torres, M.P. [California State Univ., Humbolt, CA (United States)

    1995-11-01

    By the middle of the 21st century earth`s ambient CO{sub 2} level is expected to increase two-fold ({approximately}350 umol/L). Higher levels of CO{sub 2} are expected to cause major changes in the morphological, physiological, and biochemical traits of the world`s vegetation. Therefore, we constructed an experiment designed to measure the long-term acclimation processes of Pinus Ponderosa. As a prominent forest conifer, Pinus Ponderosa is useful when assessing a large scale global carbon budget. Eighteen genetically variable families were exposed to 3 different levels of CO{sub 2} (350 umol/L, 525 umol/L, 700 umol/L), for three years. Acclimation responses were quantified by assays of photosynthetic rate, chlorophyll fluorescence, and chlorophyll pigment concentrations.

  16. Responses of photosynthetic parameters to drought in subtropical forest ecosystem of China

    Science.gov (United States)

    Zhou, Lei; Wang, Shaoqiang; Chi, Yonggang; Li, Qingkang; Huang, Kun; Yu, Quanzhou

    2015-12-01

    The mechanism underlying the effect of drought on the photosynthetic traits of leaves in forest ecosystems in subtropical regions is unclear. In this study, three limiting processes (stomatal, mesophyll and biochemical limitations) that control the photosynthetic capacity and three resource use efficiencies (intrinsic water use efficiency (iWUE), nitrogen use efficiency (NUE) and light use efficiency (LUE)), which were characterized as the interactions between photosynthesis and environmental resources, were estimated in two species (Schima superba and Pinus massoniana) under drought conditions. A quantitative limitation analysis demonstrated that the drought-induced limitation of photosynthesis in Schima superba was primarily due to stomatal limitation, whereas for Pinus massoniana, both stomatal and non-stomatal limitations generally exhibited similar magnitudes. Although the mesophyll limitation represented only 1% of the total limitation in Schima superba, it accounted for 24% of the total limitations for Pinus massoniana. Furthermore, a positive relationship between the LUE and NUE and a marginally negative relationship or trade-off between the NUE and iWUE were observed in the control plots. However, drought disrupted the relationships between the resource use efficiencies. Our findings may have important implications for reducing the uncertainties in model simulations and advancing the understanding of the interactions between ecosystem functions and climate change.

  17. Genetic analysis of biomass and photosynthetic parameters in wheat grown in different light intensities

    Institute of Scientific and Technical Information of China (English)

    Hongwei Li; Gui Wang; Qi Zheng; Bin Li; Ruilian Jing; Zhensheng Li

    2014-01-01

    Growth light intensities largely determine photo-synthesis, biomass, and grain yield of cereal crops. To explore the genetic basis of light responses of biomass and photosynthetic parameters in wheat (Triticum aestivum L.), a quantitative trait locus (QTL) analysis was carried out in a doubled haploid (DH) population grown in low light (LL), medium light (ML), and high light (HL), respectively. The results showed that the wheat seedlings grown in HL produced more biomass with lower total chlorophyll content (Chl), carotenoid content, and maximum photochemical efficiency of photosystem II (Fv/Fm) while the wheat seed-lings grown in LL produced less biomass with higher Chl compared with those grown in ML. In total, 48 QTLs were identified to be associated with the investigated parameters in relation to growth light intensities. These QTLs were mapped to 15 chromosomes which individually explained 6.3%-36.0% of the phenotypic variance, of which chromo-somes 3A, 1D, and 6B were specifically involved in LL response, 5D and 7A specifically involved in ML response, and 4B specifically involved in HL response. Several light-responsive QTLs were co-located with QTLs for photosyn-thetic parameters, biomass, and grain weight under various conditions which may provide new hints to uncover the genetic control of photosynthesis, biomass, and grain weight.

  18. Acquiring taste in home economics?

    DEFF Research Database (Denmark)

    Stenbak Larsen, Christian

    2015-01-01

    appreciated by the group of boys, and others again learned to stick with their idiosyncrasies when pressured by the teacher. Conclusions: Children were acquiring taste in the home economic lessons, but not only the kind of tastes that the teacher had planned for. This leads to reflections on the very complex...

  19. Acquired Equivalence Changes Stimulus Representations

    Science.gov (United States)

    Meeter, M.; Shohamy, D.; Myers, C. E.

    2009-01-01

    Acquired equivalence is a paradigm in which generalization is increased between two superficially dissimilar stimuli (or antecedents) that have previously been associated with similar outcomes (or consequents). Several possible mechanisms have been proposed, including changes in stimulus representations, either in the form of added associations or…

  20. Acquired aplastic anemia in children.

    Science.gov (United States)

    Hartung, Helge D; Olson, Timothy S; Bessler, Monica

    2013-12-01

    This article provides a practice-based and concise review of the etiology, diagnosis, and management of acquired aplastic anemia in children. Bone marrow transplantation, immunosuppressive therapy, and supportive care are discussed in detail. The aim is to provide the clinician with a better understanding of the disease and to offer guidelines for the management of children with this uncommon yet serious disorder.

  1. Post febrile acquired cutis laxa

    Directory of Open Access Journals (Sweden)

    Muthukumaran R

    1999-01-01

    Full Text Available Acquired cutis laxa following enteric fever has been described in a male in the neck region. Biopsy revealed fragmented elastic fibres in the dermis which were better visualised with special stain for elastic tissue. This case is reported for rarity of its occurrence at the localised site following febrile illness.

  2. Complement's participation in acquired immunity

    DEFF Research Database (Denmark)

    Nielsen, Claus Henrik; Leslie, Robert Graham Quinton

    2002-01-01

    in which antigen is seen, be it alone or in association with natural or induced antibodies and/or C3-complement fragments. The aim of this review is to describe the present status of our understanding of complement's participation in acquired immunity and the regulation of autoimmune responses....

  3. Acquired causes of intestinal malabsorption

    NARCIS (Netherlands)

    van der Heide, F.

    This review focuses on the acquired causes, diagnosis, and treatment of intestinal malabsorption. Intestinal absorption is a complex process that depends on many variables, including the digestion of nutrients within the intestinal lumen, the absorptive surface of the small intestine, the membrane

  4. Power and Autistic Traits

    Science.gov (United States)

    Overskeid, Geir

    2016-01-01

    Autistic traits can help people gain and sustain power, and has probably done so throughout history, says the present paper. A number of testable claims follow from this assumption. First, the powerful should have more autistic traits than others – which they do appear to have. Among other things, powerful people, and those with many autistic traits, tend to prefer solitary activities and are often aloof. Moreover, they are often rigid and socially insensitive, low on empathy and with low scores on the trait of agreeableness – and as a rule they do not have many friends. Both groups are also more self-centered than others, more honest, less submissive, more sensitive to slights, and with a stronger tendency to engage in abstract thinking. They tend to behave in bossy or dominant ways, and their moral judgment is more based on rules than on feelings. In addition to experimental evidence, I cite biographies showing that a surprising number of presidents, prime ministers and other powerful people seem to have had traits like those in question – and interestingly, in animals, leaders are often rigid and insensitive to group members’ needs and feelings, mostly acting the way they are themselves inclined to, not responding much to others. Problem solving is important in leadership, and people with many autistic traits appear often to be better thinkers than typical subjects with similar IQs. However, these and other congruities could be coincidences. Hence the question of whether traits the two groups have in common also have a common cause constitutes a strong test of the paper’s thesis – and a common cause does appear to exist, in the form of testosterone’s effects on the central nervous system. Finally, there is evidence that, other things equal, powerful men have more reproductive success than others. If men wielding power do indeed have more autistic traits than those less powerful, this will lead to, other things equal, such traits becoming more

  5. Power and Autistic Traits

    Directory of Open Access Journals (Sweden)

    Geir Overskeid

    2016-08-01

    Full Text Available Autistic traits can help people gain and sustain power, and has probably done so throughout history, says the present paper. A number of testable claims follow from this assumption. First, the powerful should have more autistic traits than others – which they do appear to have. Among other things, powerful people, and those with many autistic traits, tend to prefer solitary activities and are often aloof. Moreover, they are often rigid and socially insensitive, low on empathy and with low scores on the trait of agreeableness -- and as a rule they do not have many friends. Both groups are also more self-centered than others, more honest, less submissive, more sensitive to slights, and with a stronger tendency to engage in abstract thinking. They tend to behave in bossy or dominant ways, and their moral judgment is more based on rules than on feelings. In addition to experimental evidence, I cite biographies showing that a surprising number of presidents, prime ministers and other powerful people seem to have had traits like those in question – and interestingly, in animals, leaders are often rigid and insensitive to group members’ needs and feelings, mostly acting the way they are themselves inclined to, not responding much to others. Problem solving is important in leadership, and people with many autistic traits appear often to be better thinkers than typical subjects with similar IQs. However, these and other congruities could be coincidences. Hence the question of whether traits the two groups have in common also have a common cause constitutes a strong test of the paper’s thesis – and a common cause does appear to exist, in the form of testosterone’s effects on the central nervous system. Finally, there is evidence that, other things equal, powerful men have more reproductive success than others. If men wielding power do indeed have more autistic traits than those less powerful, this will lead to, other things equal, such traits

  6. Trait Acclimation Mitigates Mortality Risks of Tropical Canopy Trees under Global Warming.

    Science.gov (United States)

    Sterck, Frank; Anten, Niels P R; Schieving, Feike; Zuidema, Pieter A

    2016-01-01

    There is a heated debate about the effect of global change on tropical forests. Many scientists predict large-scale tree mortality while others point to mitigating roles of CO2 fertilization and - the notoriously unknown - physiological trait acclimation of trees. In this opinion article we provided a first quantification of the potential of trait acclimation to mitigate the negative effects of warming on tropical canopy tree growth and survival. We applied a physiological tree growth model that incorporates trait acclimation through an optimization approach. Our model estimated the maximum effect of acclimation when trees optimize traits that are strongly plastic on a week to annual time scale (leaf photosynthetic capacity, total leaf area, stem sapwood area) to maximize carbon gain. We simulated tree carbon gain for temperatures (25-35°C) and ambient CO2 concentrations (390-800 ppm) predicted for the 21st century. Full trait acclimation increased simulated carbon gain by up to 10-20% and the maximum tolerated temperature by up to 2°C, thus reducing risks of tree death under predicted warming. Functional trait acclimation may thus increase the resilience of tropical trees to warming, but cannot prevent tree death during extremely hot and dry years at current CO2 levels. We call for incorporating trait acclimation in field and experimental studies of plant functional traits, and in models that predict responses of tropical forests to climate change.

  7. Trait acclimation mitigates mortality risks of tropical canopy trees under global warming

    Directory of Open Access Journals (Sweden)

    Frank eSterck

    2016-05-01

    Full Text Available There is a heated debate about the effect of global change on tropical forests. Many scientists predict large-scale tree mortality while others point to mitigating roles of CO2 fertilization and – the notoriously unknown – physiological trait acclimation of trees. In this opinion article we provided a first quantification of the potential of trait acclimation to mitigate the negative effects of warming on tropical canopy tree growth and survival. We applied a physiological tree growth model that incorporates trait acclimation through an optimization approach. Our model estimated the maximum effect of acclimation when trees optimize traits that are strongly plastic on a week to annual time scale (leaf photosynthetic capacity, total leaf area, stem sapwood area to maximize carbon gain. We simulated tree carbon gain for temperatures (25-35ºC and ambient CO2 concentrations (390-800 ppm predicted for the 21st century. Full trait acclimation increased simulated carbon gain by up to 10-20% and the maximum tolerated temperature by up to 2ºC, thus reducing risks of tree death under predicted warming. Functional trait acclimation may thus increase the resilience of tropical trees to warming, but cannot prevent tree death during extremely hot and dry years at current CO2 levels. We call for incorporating trait acclimation in field and experimental studies of plant functional traits, and in models that predict responses of tropical forests to climate change.

  8. 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

    2014-04-01

    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.

  9. 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.

  10. [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.

  11. The OzT8 locus in rice protects leaf carbon assimilation rate and photosynthetic capacity under ozone stress.

    Science.gov (United States)

    Chen, Charles P; Frei, Michael; Wissuwa, Matthias

    2011-07-01

    Tropospheric ozone (O₃) is a phytotoxic air pollutant whose current background concentrations in parts of East Asia have caused estimated rice yield losses of up to 20%; currently, however, little is known about the mechanisms of O₃ tolerance in rice. We previously identified a quantitative trait locus (QTL) in rice called OzT8, which was associated with relative dry weight under ozone stress. The photosynthetic response in SL46, a Nipponbare (NB)-Kasalath chromosome segment substitution line (SL) containing the OzT8 locus, was compared to the parent NB in multiple ozone fumigation experiments (100 ppb, 8 h d⁻¹, 23 d). By day 23, SL46 showed significantly less reduction of photosynthetic capacity compared to NB; the maximum carboxylation rate of ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco) decreased by 24% in SL46 compared to 49% in NB, and the maximum electron transport rate decreased by 16 and 39%, respectively. The midday carbon assimilation rates also showed a similar trend, but there was no genotypic difference in stomatal conductance. These results indicate that the OzT8 locus confers ozone tolerance via biochemical acclimation, not avoidance, making it a potentially valuable target for breeding of ozone tolerance into future rice lines. The sequence of photosynthetic response of rice to ozone stress and related tolerance factors are also discussed.

  12. Cerebellum and personality traits.

    Science.gov (United States)

    Petrosini, Laura; Cutuli, Debora; Picerni, Eleonora; Laricchiuta, Daniela

    2015-02-01

    Personality traits are multidimensional traits comprising cognitive, emotional, and behavioral characteristics, and a wide array of cerebral structures mediate individual variability. Differences in personality traits covary with brain morphometry in specific brain regions. A cerebellar role in emotional and affective processing and on personality characteristics has been suggested. In a large sample of healthy subjects of both sexes and differently aged, the macro- and micro-structural variations of the cerebellum were correlated with the scores obtained in the Temperament and Character Inventory (TCI) by Cloninger. Cerebellar volumes were associated positively with Novelty Seeking scores and negatively with Harm Avoidance scores. Given the cerebellar contribution in personality traits and emotional processing, we investigated the cerebellar involvement even in alexithymia, construct of personality characterized by impairment in cognitive, emotional, and affective processing. Interestingly, the subjects with high alexithymic traits had larger volumes in the bilateral Crus 1. The cerebellar substrate for some personality dimensions extends the relationship between personality and brain areas to a structure up to now thought to be involved mainly in motor and cognitive functions, much less in emotional processes and even less in personality individual differences. The enlarged volumes of Crus 1 in novelty seekers and alexithymics support the tendency to action featuring both personality constructs. In fact, Novelty Seeking and alexithymia are rooted in behavior and inescapably have a strong action component, resulting in stronger responses in the structures more focused on action and embodiment, as the cerebellum is.

  13. Mapping Foliar Traits Across Biomes Using Imaging Spectroscopy: A Synthesis

    Science.gov (United States)

    Townsend, P. A.; Singh, A.; Wang, Z.

    2016-12-01

    One of the great promises of imaging spectroscopy - also known as hyperspectral remote sensing - is the ability to map the spatial variation in foliar functional traits, such as nitrogen concentration, pigments, leaf structure, photosynthetic capacity and secondary biochemistry, that drive terrestrial ecosystem processes. A remote-sensing approach enables characterization of within- and between-biome variations that may be crucial to understanding ecosystem responses to pests, pathogens and environmental change. We provide a synthesis of the foliar traits that can be mapped from imaging spectroscopy, as well as an overview of both the major applications of trait maps derived from hyperspectral imagery and current gaps in our knowledge and capacity. Specifically, we make the case that a global imaging spectroscopy mission will provide unique and urgent measurements necessary to understand the response of agricultural and natural systems to rapid global changes. Finally, we present a quantitative framework to utilize imaging spectroscopy to characterize spatial and temporal variation in foliar traits within and between biomes. From this we can infer the dynamics of vegetation function across ecosystems, especially in transition zones and environmentally sensitive systems. Eventual launch of a global imaging spectroscopy mission will enable collection of narrowband VSWIR measurements that will help close major gaps in our understanding of biogeochemical cycles and improve representation of vegetated biomes in Earth system process models.

  14. Occupationally Acquired American Cutaneous Leishmaniasis

    Directory of Open Access Journals (Sweden)

    Maria Edileuza Felinto de Brito

    2012-01-01

    Full Text Available We report two occupationally acquired cases of American cutaneous leishmaniasis (ACL: one accidental laboratory autoinoculation by contaminated needlestick while handling an ACL lesion sample, and one acquired during field studies on bird biology. Polymerase chain reaction (PCR assays of patient lesions were positive for Leishmania, subgenus Viannia. One isolate was obtained by culture (from patient 2 biopsy samples and characterized as Leishmania (Viannia naiffi through an indirect immunofluorescence assay (IFA with species-specific monoclonal antibodies (mAbs and by multilocus enzyme electrophoresis (MLEE. Patients were successfully treated with N-methyl-glucamine. These two cases highlight the potential risks of laboratory and field work and the need to comply with strict biosafety procedures in daily routines. The swab collection method, coupled with PCR detection, has greatly improved ACL laboratory diagnosis.

  15. Nursing home-acquired pneumonia.

    Science.gov (United States)

    El Solh, Ali A

    2009-02-01

    Nursing home-acquired pneumonia (NHAP) was first described in 1978. Since then there has been much written regarding NHAP and its management despite the lack of well-designed studies in this patient population. The most characteristic features of patients with NHAP are the atypical presentation, which may lead to delay in diagnosis and therapy. The microbial etiology of pneumonia encompasses a wide spectrum that spans microbes recovered from patients with community-acquired pneumonia to organisms considered specific only to nosocomial settings. Decision to transfer a nursing home patient to an acute care facility depends on a host of factors, which include the level of staffing available at the nursing home, patients' advance directives, and complexity of treatment. The presence of risk factors for multidrug-resistant pathogens dictates approach to therapy. Prevention remains the cornerstone of reducing the incidence of disease. Despite the advance in medical services, mortality from NHAP remains high.

  16. Occupationally Acquired American Cutaneous Leishmaniasis

    Science.gov (United States)

    Felinto de Brito, Maria Edileuza; Andrade, Maria Sandra; de Almeida, Éricka Lima; Medeiros, Ângela Cristina Rapela; Werkhäuser, Roberto Pereira; de Araújo, Ana Isabele Freitas; Brandão-Filho, Sinval Pinto; Paiva de Almeida, Alzira Maria; Gomes Rodrigues, Eduardo Henrique

    2012-01-01

    We report two occupationally acquired cases of American cutaneous leishmaniasis (ACL): one accidental laboratory autoinoculation by contaminated needlestick while handling an ACL lesion sample, and one acquired during field studies on bird biology. Polymerase chain reaction (PCR) assays of patient lesions were positive for Leishmania, subgenus Viannia. One isolate was obtained by culture (from patient 2 biopsy samples) and characterized as Leishmania (Viannia) naiffi through an indirect immunofluorescence assay (IFA) with species-specific monoclonal antibodies (mAbs) and by multilocus enzyme electrophoresis (MLEE). Patients were successfully treated with N-methyl-glucamine. These two cases highlight the potential risks of laboratory and field work and the need to comply with strict biosafety procedures in daily routines. The swab collection method, coupled with PCR detection, has greatly improved ACL laboratory diagnosis. PMID:23227369

  17. CNOOC Acquires Oversea Assets Successfully

    Institute of Scientific and Technical Information of China (English)

    Hu Senlin

    2006-01-01

    @@ After last year CNOOC's bidding for buy the US energy company Unocal Corp lost out to the Chevron Corporation, it conducted the crossing-border asset-acquirement again in the beginning of this year. On Jan. 9, 2006,CNOOC Ltd signed a definitive agreement with Nigeria South Atlantic Petroleum Limited (SAPETRO) to acquire a 45 % working interest in an offshore oil developing license OML 130 in Nigeria for US$2.268 billion cash. The purchase will be funded by the internal capital resources of CNOOC Ltd. In which, US$1.75 billion will pay for buying SAPETRO, and the remaining cash will be used to pay for the early operation cost.

  18. A method to determine photosynthetic activity from oxygen microsensor data in biofilms subjected to evaporation.

    Science.gov (United States)

    Li, Tong; Podola, Björn; de Beer, Dirk; Melkonian, Michael

    2015-10-01

    Phototrophic biofilms are widely distributed in nature and their ecological importance is well recognized. More recently, there has been a growing interest in using artificial phototrophic biofilms in innovative photobioreactors for production of microalgal biomass in biotechnological applications. To study physiological processes within these biofilms, microsensors have been applied in several studies. Here, the 'light-dark shift method' relies on measurement of photosynthetic activity in terms of light-induced oxygen production. However, when applied to non-submerged biofilms that can be found in numerous locations in nature, as well as in some types of photobioreactors, limitations of this approach are obvious due to rapid removal of gaseous species at the biofilm surface. Here, we introduce a mathematical correction to recover the distribution of the actual photosynthetic activity along the depth gradient in the biofilm, based on a numerical solution of the inversed diffusion equation of oxygen. This method considers changes in mass transport during the measurement period as can found on biofilms possessing a thin flow/mass transfer boundary layer (e. g., non-submerged biofilms). Using both simulated and real microsensor data, the proposed method was shown to be much more accurate than the classical method, which leads to underestimations of rates near the biofilm surface. All test profiles could be recovered with a high fit. According to our simulated microsensor measurements, a depth resolution of ≤20 μm is recommended near the surface. We conclude that our method strongly improves the quality of data acquired from light-dark measurements of photosynthetic activity in biofilms.

  19. [Acquired disorders of color vision].

    Science.gov (United States)

    Lascu, Lidia; Balaş, Mihaela

    2002-01-01

    This article is a general view of acquired disorders of color vision. The revision of the best known methods and of the etiopathogenic classification is not very important in ophthalmology but on the other hand, the detection of the blue defect advertise and associated ocular pathology. There is a major interest in serious diseases as multiple sclerosis, AIDS, diabetes melitus, when the first ocular sign can be a defect in the color vision.

  20. 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

  1. 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

  2. Towards autotrophic tissue engineering: Photosynthetic gene therapy for regeneration.

    Science.gov (United States)

    Chávez, Myra Noemi; Schenck, Thilo Ludwig; Hopfner, Ursula; Centeno-Cerdas, Carolina; Somlai-Schweiger, Ian; Schwarz, Christian; Machens, Hans-Günther; Heikenwalder, Mathias; Bono, María Rosa; Allende, Miguel L; Nickelsen, Jörg; Egaña, José Tomás

    2016-01-01

    The use of artificial tissues in regenerative medicine is limited due to hypoxia. As a strategy to overcome this drawback, we have shown that photosynthetic biomaterials can produce and provide oxygen independently of blood perfusion by generating chimeric animal-plant tissues during dermal regeneration. In this work, we demonstrate the safety and efficacy of photosynthetic biomaterials in vivo after engraftment in a fully immunocompetent mouse skin defect model. Further, we show that it is also possible to genetically engineer such photosynthetic scaffolds to deliver other key molecules in addition to oxygen. As a proof-of-concept, biomaterials were loaded with gene modified microalgae expressing the angiogenic recombinant protein VEGF. Survival of the algae, growth factor delivery and regenerative potential were evaluated in vitro and in vivo. This work proposes the use of photosynthetic gene therapy in regenerative medicine and provides scientific evidence for the use of engineered microalgae as an alternative to deliver recombinant molecules for gene therapy.

  3. 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 efficienc

  4. Native mass spectrometry of photosynthetic pigment–protein complexes

    National Research Council Canada - National Science Library

    Zhang, Hao; Cui, Weidong; Gross, Michael L; Blankenship, Robert E

    2013-01-01

    .... This approach is now a powerful tool to investigate protein complexes. This article reviews the background of native MS of protein complexes and describes its strengths, taking photosynthetic pigment...

  5. 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

  6. Environmental regulation of intrinsic photosynthetic capacity: an integrated view.

    Science.gov (United States)

    Demmig-Adams, Barbara; Stewart, Jared J; Adams, William W

    2017-06-01

    Environmental modulation of photosynthetic capacity is reviewed in the context of its assessment and its regulation, genetic differences among species and ecotypes, and links to plant stress tolerance and productivity. Modulation of intrinsic photosynthetic capacity matches investment in photosynthetic components to opportunity for CO2 uptake and productivity in specific environments, with exceptionally high rates during particularly narrow windows of opportunity. Response varies among species and ecotypes and should be evaluated on multiple reference bases as well as chloroplast, leaf, and whole plant scales. Photosynthetic capacity, total foliar vascular transport capacity, and plant sink strength are modulated in concert. Switching among alternative target sinks and alternative foliar vascular architectures may provide avenues for co-optimization of productivity and stress tolerance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Functional Implications of Photosystem II Crystal Formation in Photosynthetic Membranes

    NARCIS (Netherlands)

    Tietz, Stefanie; Puthiyaveetil, Sujith; Enlow, Heather M; Yarbrough, Robert; Wood, Magnus; Semchonok, Dmitry A; Lowry, Troy; Li, Zhirong; Jahns, Peter; Boekema, Egbert J; Lenhert, Steven; Niyogi, Krishna K; Kirchhoff, Helmut

    2015-01-01

    The structural organization of proteins in biological membranes can affect their function. Photosynthetic thylakoid membranes in chloroplasts have the remarkable ability to change their supramolecular organization between disordered and semicrystalline states. Although the change to the semicrystall

  8. 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.

  9. 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.

  10. 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.

  11. Photocurrent of a single photosynthetic protein

    Science.gov (United States)

    Gerster, Daniel; Reichert, Joachim; Bi, Hai; Barth, Johannes V.; Kaniber, Simone M.; Holleitner, Alexander W.; Visoly-Fisher, Iris; Sergani, Shlomi; Carmeli, Itai

    2012-10-01

    Photosynthesis is used by plants, algae and bacteria to convert solar energy into stable chemical energy. The initial stages of this process--where light is absorbed and energy and electrons are transferred--are mediated by reaction centres composed of chlorophyll and carotenoid complexes. It has been previously shown that single small molecules can be used as functional components in electric and optoelectronic circuits, but it has proved difficult to control and probe individual molecules for photovoltaic and photoelectrochemical applications. Here, we show that the photocurrent generated by a single photosynthetic protein--photosystem I--can be measured using a scanning near-field optical microscope set-up. One side of the protein is anchored to a gold surface that acts as an electrode, and the other is contacted by a gold-covered glass tip. The tip functions as both counter electrode and light source. A photocurrent of ~10 pA is recorded from the covalently bound single-protein junctions, which is in agreement with the internal electron transfer times of photosystem I.

  12. Photosynthetic light harvesting: excitons and coherence.

    Science.gov (United States)

    Fassioli, Francesca; Dinshaw, Rayomond; Arpin, Paul C; Scholes, Gregory D

    2014-03-06

    Photosynthesis begins with light harvesting, where specialized pigment-protein complexes transform sunlight into electronic excitations delivered to reaction centres to initiate charge separation. There is evidence that quantum coherence between electronic excited states plays a role in energy transfer. In this review, we discuss how quantum coherence manifests in photosynthetic light harvesting and its implications. We begin by examining the concept of an exciton, an excited electronic state delocalized over several spatially separated molecules, which is the most widely available signature of quantum coherence in light harvesting. We then discuss recent results concerning the possibility that quantum coherence between electronically excited states of donors and acceptors may give rise to a quantum coherent evolution of excitations, modifying the traditional incoherent picture of energy transfer. Key to this (partially) coherent energy transfer appears to be the structure of the environment, in particular the participation of non-equilibrium vibrational modes. We discuss the open questions and controversies regarding quantum coherent energy transfer and how these can be addressed using new experimental techniques.

  13. Quantum measurement corrections to CIDNP in photosynthetic reaction centers

    OpenAIRE

    Kominis, I. 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 here show that the recently understood fundamental quantum dynamics of radical-ion-pair reactions open up a new and comple...

  14. The Photosynthetic Reaction Center from the Purple Bacterium Rhodopseudomonas viridis

    Science.gov (United States)

    Deisenhofer, Johann; Michel, Hartmut

    1989-09-01

    The history and methods of membrane protein crystallization are described. The solution of the structure of the photosynthetic reaction center from the bacterium Rhodopseudomonas viridis is described, and the structure of this membrane protein complex is correlated with its function as a light-driven electron pump across the photosynthetic membrane. Conclusions about the structure of the photosystem II reaction center from plants are drawn, and aspects of membrane protein structure are discussed.

  15. Hydrogen photoproduction by use of photosynthetic organisms and biomimetic systems.

    Science.gov (United States)

    Allakhverdiev, Suleyman I; Kreslavski, Vladimir D; Thavasi, Velmurugan; Zharmukhamedov, Sergei K; Klimov, Vyacheslav V; Nagata, Toshi; Nishihara, Hiroshi; Ramakrishna, Seeram

    2009-02-01

    Hydrogen can be important clean fuel for future. Among different technologies for hydrogen production, oxygenic natural and artificial photosyntheses using direct photochemistry in synthetic complexes have a great potential to produce hydrogen, since both use clean and cheap sources: water and solar energy. Artificial photosynthesis is one way to produce hydrogen from water using sunlight by employing biomimetic complexes. However, splitting of water into protons and oxygen is energetically demanding and chemically difficult. In oxygenic photosynthetic microorganisms such as algae and cyanobacteria, water is split into electrons and protons, which during primary photosynthetic process are redirected by photosynthetic electron transport chain, and ferredoxin, to the hydrogen-producing enzymes hydrogenase or nitrogenase. By these enzymes, e- and H+ recombine and form gaseous hydrogen. Biohydrogen activity of hydrogenase can be very high but it is extremely sensitive to photosynthetic O2. In contrast, nitrogenase is insensitive to O2, but has lower activity. At the moment, the efficiency of biohydrogen production is low. However, theoretical expectations suggest that the rates of photon conversion efficiency for H2 bioproduction can be high enough (>10%). Our review examines the main pathways of H2 photoproduction by using of photosynthetic organisms and biomimetic photosynthetic systems.

  16. Rice photosynthetic productivity and PSII photochemistry under nonflooded irrigation.

    Science.gov (United States)

    He, Haibing; Yang, Ru; Jia, Biao; Chen, Lin; Fan, Hua; Cui, Jing; Yang, Dong; Li, Menglong; Ma, Fu-Yu

    2014-01-01

    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.

  17. 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.

  18. The effect of interspecific variation in photosynthetic plasticity on 4-year growth rate and 8-year survival of understorey tree seedlings in response to gap formations in a cool-temperate deciduous forest.

    Science.gov (United States)

    Oguchi, Riichi; Hiura, Tsutom; Hikosaka, Kouki

    2017-04-19

    Gap formation increases the light intensity in the forest understorey. The growth responses of seedlings to the increase in light availability show interspecific variation, which is considered to promote biodiversity in forests. At the leaf level, some species increase their photosynthetic capacity in response to gap formation, whereas others do not. Here we address the question of whether the interspecific difference in the photosynthetic response results in the interspecific variation in the growth response. If so, the interspecific difference in photosynthetic response would also contribute to species coexistence in forests. We also address the further relevant question of why some species do not increase their photosynthetic capacity. We assumed that some cost of photosynthetic plasticity may constrain acquisition of the plasticity in some species, and hypothesized that species with larger photosynthetic plasticity exhibit better growth after gap formation and lower survivorship in the shade understorey of a cool-temperate deciduous forest. We created gaps by felling canopy trees and studied the relationship between the photosynthetic response and the subsequent growth rate of seedlings. Naturally growing seedlings of six deciduous woody species were used and their mortality was examined for 8 years. The light-saturated rate of photosynthesis (Pmax) and the relative growth rate (RGR) of the seedlings of all study species increased at gap plots. The extent of these increases varied among the species. The stimulation of RGR over 4 years after gap formation was strongly correlated with change in photosynthetic capacity of newly expanded leaves. The increase in RGR and Pmax correlated with the 8-year mortality at control plots. These results suggest a trade-off between photosynthetic plasticity and the understorey shade tolerance. Gap-demanding species may acquire photosynthetic plasticity, sacrificing shade tolerances, whereas gap-independent species may acquire

  19. Changes in photosynthetic carbon metabolism in senescent leaves of chickpea, Cicer arietinum L.

    OpenAIRE

    Chandrashekhar V. Murumkar; Prakash D Chavan

    2014-01-01

    Photosynthetic processes in mature and senescent leaves of chickpea (Cicer arietinum L.) have been compared. With age, leaf photosynthetic pigments viz. chlorophyll a, chlorophyll b and carotenoids, and rate of 14°C fixation were considerably affected. Analysis of δ13C, and short term photosynthetic products showed no major change in the path of photosynthetic carbon fixation. Study of long term photosynthetic 14C assimilation revealed that in old senescent leaves, 14C incorporation into orga...

  20. Three photosynthetic patterns characterized by cluster analysis of gas exchange data in two rice populations

    OpenAIRE

    2014-01-01

    Plant photosynthetic rate is affected by stomatal status and internal CO2 carboxylation. Understanding which process determines photosynthetic rate is essential for developing strategies for breeding crops with high photosynthetic efficiency. In this study, we identified different physiological patterns of photosynthetic rate in two different rice populations. Photosynthetic gas exchange parameters were measured during the flowering stage in two rice populations. Clustering and correlation an...

  1. Photosynthetic and Molecular Markers of CO2-mediated Photosynthetic Downregulation in Nodulated Alfalfa

    Institute of Scientific and Technical Information of China (English)

    (A)lvaro Sanz-Sáez; Gorka Erice; Iker Aranjuelo; Ricardo Aroca; Juan Manuel Ruíz-Lozano; Jone Aguirreolea; Juan José Irigoyen

    2013-01-01

    Elevated CO2 leads to a decrease in potential net photosynthesis in long-term experiments and thus to a reduction in potential growth.This process is known as photosynthetic downregulation.There is no agreement on the definition of which parameters are the most sensitive for detecting CO2 acclimation.In order to investigate the most sensitive photosynthetic and molecular markers of CO2 acclimation,the effects of elevated CO2,and associated elevated temperature were analyzed in alfalfa plants inoculated with different Sinorhizobium meliloti strains.Plants (Medicago sativa L.cv.Aragón) were grown in summer or autumn in temperature gradient greenhouses (TGG).At the end of the experiment,all plants showed acclimation in both seasons,especially under elevated summer temperatures.This was probably due to the lower nitrogen (N) availability caused by decreased N2-fixation under higher temperatures.Photosynthesis measured at growth CO2 concentration,rubisco in vitro activity and maximum rate of carboxylation were the most sensitive parameters for detecting downregulation.Severe acclimation was also related with decreases in leaf nitrogen content associated with declines in rubisco content (large and small subunits) and activity that resulted in a drop in photosynthesis.Despite the sensitivity of rubisco content as a marker of acclimation,it was not coordinated with gene expression,possibly due to a lag between gene transcription and protein translation.

  2. Acquired Upper Extremity Growth Arrest.

    Science.gov (United States)

    Gauger, Erich M; Casnovsky, Lauren L; Gauger, Erica J; Bohn, Deborah C; Van Heest, Ann E

    2017-01-01

    This study reviewed the clinical history and management of acquired growth arrest in the upper extremity in pediatric patients. The records of all patients presenting from 1996 to 2012 with radiographically proven acquired growth arrest were reviewed. Records were examined to determine the etiology and site of growth arrest, management, and complications. Patients with tumors or hereditary etiology were excluded. A total of 44 patients (24 boys and 20 girls) with 51 physeal arrests who presented at a mean age of 10.6 years (range, 0.8-18.2 years) were included in the study. The distal radius was the most common site (n=24), followed by the distal humerus (n=8), metacarpal (n=6), distal ulna (n=5), proximal humerus (n=4), radial head (n=3), and olecranon (n=1). Growth arrest was secondary to trauma (n=22), infection (n=11), idiopathy (n=6), inflammation (n=2), compartment syndrome (n=2), and avascular necrosis (n=1). Twenty-six patients (59%) underwent surgical intervention to address deformity caused by the physeal arrest. Operative procedures included ipsilateral unaffected bone epiphysiodesis (n=21), shortening osteotomy (n=10), lengthening osteotomy (n=8), excision of physeal bar or bone fragment (n=2), angular correction osteotomy (n=1), and creation of single bone forearm (n=1). Four complications occurred; 3 of these required additional procedures. Acquired upper extremity growth arrest usually is caused by trauma or infection, and the most frequent site is the distal radius. Growth disturbances due to premature arrest can be treated effectively with epiphysiodesis or osteotomy. In this series, the specific site of anatomic growth arrest was the primary factor in determining treatment. [Orthopedics. 2017; 40(1):e95-e103.]. Copyright 2016, SLACK Incorporated.

  3. Pneumonia acquired in the Community

    Directory of Open Access Journals (Sweden)

    María Caridad Fragoso Marchante

    2007-06-01

    Full Text Available A bibliographical revision of the main aspects in the diagnosis and treatment of the patients suffering from pneumonia acquired in the community is carried out. Microorganisms responsible for this type of pneumonia are mention in this paper as well as the available diagnostic methods for germs isolation. Different guidelines for diagnosis and treatment of this disease published by several medical societies and scientific institutions are analyzed by means of a review of the stratification index of the patients used in each of them. Aspects related to the duration of the treatment and the possible causes associated with the unfavorable evolution are stated.

  4. 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.

  5. Enhanced Practical Photosynthetic CO2 Mitigation

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-10-15

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 7/2/2003 through 10/01/2003. As indicated in the list of accomplishments below we are preparing for the final tests necessary to meet our project goals. Specific results and accomplishments for the third quarter of 2003 include: (1) Bioreactor support systems and test facilities: (A) The solar collector used in the light delivery system showed signs of degradation and hence had to be replaced by ORNL. A set of light readings were taken after the new solar collector was installed. The readings showed an acceptable light profile. (B) 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. The improvements have been completed and the system is ready for testing. (C) The pilot scale bioreactor is ready for testing pending some information from the CRF-2 tests. (2) Organisms and Growth Surfaces: (A) The shape of the Chlorogloeopsis sp. cells (cyanobacteria) was found to be affected by environmental pH, which may be useful in culture quality control. Besides, the further investigation of this phenomenon suggested that the rate of cell adhesion to glass surface decreases upon medium alkalinization. Thus, harvesting effectiveness may be improved by increasing medium pH up to 9 before harvesting of cyanobacteria from a substratum.

  6. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-01-30

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 10/2/2003 through 1/1/2004. As indicated in the list of accomplishments below we have seen very encouraging results from the model scale tests in terms of organism growth rates and we have begun the final tests necessary to meet our project goals. Specific results and accomplishments for the fourth quarter of 2003 include: (1) Bioreactor support systems and test facilities--(A) The solar collector is working well and has survived the winter weather. (B) The improved high-flow CRF-2 test system has been used successfully to run several long-term growth tests with periodic harvesting events. The high flow harvesting system performed well. The mass measurement results after a 4-week test show 275% growth over the initial mass loading. This figure would have been higher had there been no leakage and handling losses. Carbon dating of biomass from this test is planned for carbon uptake estimation. The next test will include direct measurement of carbon uptake in addition to organism mass measurements. (C) Qualitative organism growth testing has begun in the pilot scale bioreactor. Some issues with uniformity of organism loading, fluid leakage and evaporation have surfaced and are currently being addressed, and quantitative testing will begin as soon as these problems are resolved. (2) Organisms and Growth Surfaces--(A) Montana State University (Subcontracted to do organism studies) submitted their final (3-year) project report. An abstract of the report in included in this quarterly report.

  7. Effects of UVC254 nm on the photosynthetic activity of photobionts from the astrobiologically relevant lichens Buellia frigida and Circinaria gyrosa

    Science.gov (United States)

    Meeßen, J.; Backhaus, T.; Sadowsky, A.; Mrkalj, M.; Sánchez, F. J.; de la Torre, R.; Ott, S.

    2014-10-01

    In the past decade, various astrobiological studies on different lichen species investigated the impairment of viability and photosynthetic activity by exposure to simulated or real space parameters (as vacuum, polychromatic ultraviolet (UV)-radiation and monochromatic UVC) and consistently found high post-exposure viability as well as low rates of photosynthetic impairment (de Vera et al. 2003, 2004a; 2004b; de la Torre et al. 2010; Onofri et al. 2012; Sánchez et al. 2012, 2014; Brandt et al. 2014). To achieve a better understanding of the basic mechanisms of resistance, the present study subdued isolated and metabolically active photobionts of two astrobiologically relevant lichens to UVC254 nm, examined its effect on photosynthetic activity by chlorophyll a fluorescence and characterized the UVC-induced damages by quantum yield reduction and measurements of non-photochemical quenching. The results indicate a strong impairment of photosynthetic activity, photoprotective mechanisms and overall photobiont vitality when being irradiated in the isolated and metabolically active state. In conclusion, the present study stresses the higher susceptibility of photobionts towards extreme environmental conditions as UVC-exposure, a stressor that does not occur on the Earth. By comparison with previous studies, the present results highlight the importance of protective mechanisms in lichens, such as morphological-anatomical traits (Meeßen et al. 2013), secondary lichen compounds (Meeßen et al. 2014) and the symbiont's pivotal ability to pass into anhydrobiosis when desiccating.

  8. Understanding the low photosynthetic rates of sun and shade coffee leaves: bridging the gap on the relative roles of hydraulic, diffusive and biochemical constraints to photosynthesis.

    Directory of Open Access Journals (Sweden)

    Samuel C V Martins

    Full Text Available It has long been held that the low photosynthetic rates (A of coffee leaves are largely associated with diffusive constraints to photosynthesis. However, the relative limitations of the stomata and mesophyll to the overall diffusional constraints to photosynthesis, as well as the coordination of leaf hydraulics with photosynthetic limitations, remain to be fully elucidated in coffee. Whether the low actual A under ambient CO2 concentrations is associated with the kinetic properties of Rubisco and high (photorespiration rates also remains elusive. Here, we provide a holistic analysis to understand the causes associated with low A by measuring a variety of key anatomical/hydraulic and photosynthetic traits in sun- and shade-grown coffee plants. We demonstrate that leaf hydraulic architecture imposes a major constraint on the maximisation of the photosynthetic gas exchange of coffee leaves. Regardless of the light treatments, A was mainly limited by stomatal factors followed by similar limitations associated with the mesophyll and biochemical constraints. No evidence of an inefficient Rubisco was found; rather, we propose that coffee Rubisco is well tuned for operating at low chloroplastic CO2 concentrations. Finally, we contend that large diffusive resistance should lead to large CO2 drawdown from the intercellular airspaces to the sites of carboxylation, thus favouring the occurrence of relatively high photorespiration rates, which ultimately leads to further limitations to A.

  9. A single origin of the photosynthetic organelle in different Paulinella lineages

    Directory of Open Access Journals (Sweden)

    Ishida Ken-ichiro

    2009-05-01

    Full Text Available Abstract Background Gaining the ability to photosynthesize was a key event in eukaryotic evolution because algae and plants form the base of the food chain on our planet. The eukaryotic machines of photosynthesis are plastids (e.g., chloroplast in plants that evolved from cyanobacteria through primary endosymbiosis. Our knowledge of plastid evolution, however, remains limited because the primary endosymbiosis occurred more than a billion years ago. In this context, the thecate "green amoeba" Paulinella chromatophora is remarkable because it very recently (i.e., minimum age of ≈ 60 million years ago acquired a photosynthetic organelle (termed a "chromatophore"; i.e., plastid via an independent primary endosymbiosis involving a Prochlorococcus or Synechococcus-like cyanobacterium. All data regarding P. chromatophora stem from a single isolate from Germany (strain M0880/a. Here we brought into culture a novel photosynthetic Paulinella strain (FK01 and generated molecular sequence data from these cells and from four different cell samples, all isolated from freshwater habitats in Japan. Our study had two aims. The first was to compare and contrast cell ultrastructure of the M0880/a and FK01 strains using scanning electron microscopy. The second was to assess the phylogenetic diversity of photosynthetic Paulinella to test the hypothesis they share a vertically inherited plastid that originated in their common ancestor. Results Comparative morphological analyses show that Paulinella FK01 cells are smaller than M0880/a and differ with respect to the number of scales per column. There are more distinctive, multiple fine pores on the external surface of FK01 than in M0880/a. Molecular phylogenetic analyses using multiple gene markers demonstrate these strains are genetically distinct and likely comprise separate species. The well-supported monophyly of the Paulinella chromatophora strains analyzed here using plastid-encoded 16S rRNA suggests strongly

  10. An Excel tool for deriving key photosynthetic parameters from combined gas exchange and chlorophyll fluorescence: theory and practice.

    Science.gov (United States)

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

    2016-06-01

    Combined photosynthetic gas exchange and modulated fluorometres are widely used to evaluate physiological characteristics associated with phenotypic and genotypic variation, whether in response to genetic manipulation or resource limitation in natural vegetation or crops. After describing relatively simple experimental procedures, we present the theoretical background to the derivation of photosynthetic parameters, and provide a freely available Excel-based fitting tool (EFT) that will be of use to specialists and non-specialists alike. We use data acquired in concurrent variable fluorescence-gas exchange experiments, where A/Ci and light-response curves have been measured under ambient and low oxygen. From these data, the EFT derives light respiration, initial PSII (photosystem II) photochemical yield, initial quantum yield for CO2 fixation, fraction of incident light harvested by PSII, initial quantum yield for electron transport, electron transport rate, rate of photorespiration, stomatal limitation, Rubisco (ribulose 1·5-bisphosphate carboxylase/oxygenase) rate of carboxylation and oxygenation, Rubisco specificity factor, mesophyll conductance to CO2 diffusion, light and CO2 compensation point, Rubisco apparent Michaelis-Menten constant, and Rubisco CO2 -saturated carboxylation rate. As an example, a complete analysis of gas exchange data on tobacco plants is provided. We also discuss potential measurement problems and pitfalls, and suggest how such empirical data could subsequently be used to parameterize predictive photosynthetic models.

  11. High-Throughput Phenotyping of Maize Leaf Physiological and Biochemical Traits Using Hyperspectral Reflectance1[OPEN

    Science.gov (United States)

    Yendrek, Craig R.; Tomaz, Tiago; Montes, Christopher M.; Cao, Youyuan; Morse, Alison M.; Brown, Patrick J.; McIntyre, Lauren M.; Leakey, Andrew D.B.

    2017-01-01

    High-throughput, noninvasive field phenotyping has revealed genetic variation in crop morphological, developmental, and agronomic traits, but rapid measurements of the underlying physiological and biochemical traits are needed to fully understand genetic variation in plant-environment interactions. This study tested the application of leaf hyperspectral reflectance (λ = 500–2,400 nm) as a high-throughput phenotyping approach for rapid and accurate assessment of leaf photosynthetic and biochemical traits in maize (Zea mays). Leaf traits were measured with standard wet-laboratory and gas-exchange approaches alongside measurements of leaf reflectance. Partial least-squares regression was used to develop a measure of leaf chlorophyll content, nitrogen content, sucrose content, specific leaf area, maximum rate of phosphoenolpyruvate carboxylation, [CO2]-saturated rate of photosynthesis, and leaf oxygen radical absorbance capacity from leaf reflectance spectra. Partial least-squares regression models accurately predicted five out of seven traits and were more accurate than previously used simple spectral indices for leaf chlorophyll, nitrogen content, and specific leaf area. Correlations among leaf traits and statistical inferences about differences among genotypes and treatments were similar for measured and modeled data. The hyperspectral reflectance approach to phenotyping was dramatically faster than traditional measurements, enabling over 1,000 rows to be phenotyped during midday hours over just 2 to 4 d, and offers a nondestructive method to accurately assess physiological and biochemical trait responses to environmental stress. PMID:28049858

  12. Foodborne listeriosis acquired in hospitals.

    Science.gov (United States)

    Silk, Benjamin J; McCoy, Morgan H; Iwamoto, Martha; Griffin, Patricia M

    2014-08-15

    Listeriosis is characterized by bacteremia or meningitis. We searched for listeriosis case series and outbreak investigations published in English by 2013, and assessed the strength of evidence for foodborne acquisition among patients who ate hospital food. We identified 30 reports from 13 countries. Among the case series, the median proportion of cases considered to be hospital-acquired was 25% (range, 9%-67%). The median number of outbreak-related illnesses considered to be hospital-acquired was 4.0 (range, 2-16). All patients were immunosuppressed in 18 of 24 (75%) reports with available data. Eight outbreak reports with strong evidence for foodborne acquisition in a hospital implicated sandwiches (3 reports), butter, precut celery, Camembert cheese, sausage, and tuna salad (1 report each). Foodborne acquisition of listeriosis among hospitalized patients is well documented internationally. The number of listeriosis cases could be reduced substantially by establishing hospital policies for safe food preparation for immunocompromised patients and by not serving them higher-risk foods.

  13. Pruritic acquired nevus of Ota.

    Science.gov (United States)

    Quenan, S; Strueven, V; Saxer, N; Laffitte, E; Kaya, G; Krischer, J; Hafezi, F; Le Gal, F-A

    2013-01-01

    Nevus of Ota is a unilateral, asymptomatic cutaneous and mucosal hyperpigmentation of the face that is congenital or may appear during childhood. We present a case of symptomatic acquired nevus of Ota in an adult, associated with intense pruritus, not described in the literature so far. A 32-year-old woman presented with brownish mottled macules which appeared on her face progressively over 8 days, following the distribution of the first and second divisions of the left trigeminal nerve and partially covering the iris and sclera of the left eye. She reported an intense pruritus in this area. We performed a biopsy on the left forehead, which confirmed the diagnosis of nevus of Ota. Specific stains and immunohistochemistry revealed increased numbers of mast cells. Ophthalmological tests showed acute acquired melanocytosis of the left iris and sclera. The origin of the nevus is still unclear. Several hypotheses suggest a reactivation of melanocytes during their migration from the neural crest. The pruritus reported in our patient may be explained by the increased quantity of mast cells observed in the lesion and/or neuronal stimulation of the ophthalmic and maxillary divisions of the fifth cranial nerve.

  14. Plant morphometric traits and climate gradients in northern China: a meta-analysis using quadrat and flora data.

    Science.gov (United States)

    Meng, Ting-Ting; Ni, Jian; Harrison, Sandy P

    2009-11-01

    The collection of field data on plant traits is time consuming and this makes it difficult to examine changing patterns of traits along large-scale climate gradients. The present study tests whether trait information derived from regional floras can be used in conjunction with pre-existing quadrat data on species presence to derive meaningful relationships between specific morphometric traits and climate. Quadrat records were obtained for 867 species in 404 sites from northern China (38-49 degrees N, 82-132 degrees E) together with information on the presence/absence of key traits from floras. Bioclimate parameters for each site were calculated using the BIOME3 model. Principal component analysis and correlation analysis were conducted to determine the most important climate factors. The Akaike Information Criterion was used to select the best relationship between each trait and climate. Canonical correspondence analysis was used to explore the relationships between climate and trait occurrence. The changing abundance of life form, leaf type, phenology, photosynthetic pathway, leaf size and several other morphometric traits are determined by gradients in plant-available moisture (as measured by the ratio of actual to potential evapotranspiration: alpha), growing-season temperature (as measured by growing degree-days on a 0 degrees base: GDD(0)) or a combination of these. Different plant functional types (PFTs, as defined by life form, leaf type and phenology) reach maximum abundance in distinct areas of this climate space: for example, evergreen trees occur in the coldest, wettest environments (GDD(0) 0.38), and deciduous scale-leaved trees occur in drier, warmer environments than deciduous broad-leaved trees. Most leaf-level traits show similar relationships with climate independently of PFT: for example, leaf size in all PFTs increases as the environment becomes wetter and cooler. However, some traits (e.g. petiole length) display different relationships with

  15. 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

    . These synthetic systems are providing a deeper understanding of structural and environmental effects on the interactions between carotenoids and tetrapyrroles and thereby better defining their role in controlling natural photosynthetic systems.

  16. Genetic Determinism and the Innate-Acquired Distinction in Medicine.

    Science.gov (United States)

    Kronfeldner, Maria E

    2009-06-01

    This article illustrates in which sense genetic determinism is still part of the contemporary interactionist consensus in medicine. Three dimensions of this consensus are discussed: kinds of causes, a continuum of traits ranging from monogenetic diseases to car accidents, and different kinds of determination due to different norms of reaction. On this basis, this article explicates in which sense the interactionist consensus presupposes the innate-acquired distinction. After a descriptive Part 1, Part 2 reviews why the innate-acquired distinction is under attack in contemporary philosophy of biology. Three arguments are then presented to provide a limited and pragmatic defense of the distinction: an epistemic, a conceptual, and a historical argument. If interpreted in a certain manner, and if the pragmatic goals of prevention and treatment (ideally specifying what medicine and health care is all about) are taken into account, then the innate-acquired distinction can be a useful epistemic tool. It can help, first, to understand that genetic determination does not mean fatalism, and, second, to maintain a system of checks and balances in the continuing nature-nurture debates.

  17. Photosynthetic terpene hydrocarbon production for fuels and chemicals.

    Science.gov (United States)

    Wang, Xin; Ort, Donald R; Yuan, Joshua S

    2015-02-01

    Photosynthetic hydrocarbon production bypasses the traditional biomass hydrolysis process and represents the most direct conversion of sunlight energy into the next-generation biofuels. As a major class of biologically derived hydrocarbons with diverse structures, terpenes are also valuable in producing a variety of fungible bioproducts in addition to the advanced 'drop-in' biofuels. However, it is highly challenging to achieve the efficient redirection of photosynthetic carbon and reductant into terpene biosynthesis. In this review, we discuss four major scientific and technical barriers for photosynthetic terpene production and recent advances to address these constraints. Collectively, photosynthetic terpene production needs to be optimized in a systematic fashion, in which the photosynthesis improvement, the optimization of terpene biosynthesis pathway, the improvement of key enzymes and the enhancement of sink effect through terpene storage or secretion are all important. New advances in synthetic biology also offer a suite of potential tools to design and engineer photosynthetic terpene platforms. The systemic integration of these solutions may lead to 'disruptive' technologies to enable biofuels and bioproducts with high efficiency, yield and infrastructure compatibility.

  18. Photosynthetic terpene hydrocarbon production for fuels and chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X; Ort, DR; Yuan, JS

    2015-01-28

    Photosynthetic hydrocarbon production bypasses the traditional biomass hydrolysis process and represents the most direct conversion of sunlight energy into the next-generation biofuels. As a major class of biologically derived hydrocarbons with diverse structures, terpenes are also valuable in producing a variety of fungible bioproducts in addition to the advanced drop-in' biofuels. However, it is highly challenging to achieve the efficient redirection of photosynthetic carbon and reductant into terpene biosynthesis. In this review, we discuss four major scientific and technical barriers for photosynthetic terpene production and recent advances to address these constraints. Collectively, photosynthetic terpene production needs to be optimized in a systematic fashion, in which the photosynthesis improvement, the optimization of terpene biosynthesis pathway, the improvement of key enzymes and the enhancement of sink effect through terpene storage or secretion are all important. New advances in synthetic biology also offer a suite of potential tools to design and engineer photosynthetic terpene platforms. The systemic integration of these solutions may lead to disruptive' technologies to enable biofuels and bioproducts with high efficiency, yield and infrastructure compatibility.

  19. Personality Traits and Administrators

    OpenAIRE

    Anitha V

    2008-01-01

    Administration is the art of getting tasks done by utilizing the resources and coordinating the people. Administrators give trigger to the administration by coordinating, and directing all parts of an organization by managing the tangible and intangible resources of the organization. The qualities of leadership are therefore a critical determinant of organizational success. The theories of leadership (Trait to Transformational leadership theory) have strived to look into the aspects that make...

  20. Thalassaemia trait and pregnancy.

    OpenAIRE

    1985-01-01

    The haematological variables, haematinic state, and placental function of more than 2000 pregnant women, heterozygous for either alpha- or beta-thalassaemia genes, were examined during pregnancy. Four features emerged. Firstly, it was possible by discriminant function analysis of haematological variables to distinguish in pregnant patients between the anaemia caused by thalassaemia trait and that caused by iron deficiency. Secondly, patients with thalassaemia become significantly more anaemic...

  1. Complement's participation in acquired immunity

    DEFF Research Database (Denmark)

    Nielsen, Claus Henrik; Leslie, Robert Graham Quinton

    2002-01-01

    of the B cell receptor for antigen (BCR), a complex composed of the iC3b/C3d fragment-binding complement type 2 receptor (CR2, CD21) and its signaling element CD19 and the IgG-binding receptor FcgammaRIIb (CD32). The positive or negative outcome of signaling through this triad is determined by the context...... in which antigen is seen, be it alone or in association with natural or induced antibodies and/or C3-complement fragments. The aim of this review is to describe the present status of our understanding of complement's participation in acquired immunity and the regulation of autoimmune responses....

  2. Lymphoma in acquired generalized lipodystrophy.

    Science.gov (United States)

    Brown, Rebecca J; Chan, Jean L; Jaffe, Elaine S; Cochran, Elaine; DePaoli, Alex M; Gautier, Jean-Francois; Goujard, Cecile; Vigouroux, Corinne; Gorden, Phillip

    2016-01-01

    Acquired generalized lipodystrophy (AGL) is a rare disease thought to result from autoimmune destruction of adipose tissue. Peripheral T-cell lymphoma (PTCL) has been reported in two AGL patients. We report five additional cases of lymphoma in AGL, and analyze the role of underlying autoimmunity and recombinant human leptin (metreleptin) replacement in lymphoma development. Three patients developed lymphoma during metreleptin treatment (two PTCL and one ALK-positive anaplastic large cell lymphoma), and two developed lymphomas (mycosis fungoides and Burkitt lymphoma) without metreleptin. AGL is associated with high risk for lymphoma, especially PTCL. Autoimmunity likely contributes to this risk. Lymphoma developed with or without metreleptin, suggesting metreleptin does not directly cause lymphoma development; a theoretical role of metreleptin in lymphoma progression remains possible. For most patients with AGL and severe metabolic complications, the proven benefits of metreleptin on metabolic disease will likely outweigh theoretical risks of metreleptin in lymphoma development or progression.

  3. Bejel: acquirable only in childhood?

    Science.gov (United States)

    Rothschild, Bruce M; Rothschild, Christine; Naples, Virginia; Billard, Michel; Panero, Barbara

    2006-10-01

    Bejel clearly has a long history in the Middle East and the Sudan, but was it transmitted to Europe? As the major manifestation of bejel is presence of periosteal reaction in 20-40% of afflicted populations, absence of significant population frequency of periosteal reaction in Europe would exclude that diagnosis. Examination of skeletal populations from continental Europe revealed no significant periosteal reaction at the time of and immediately subsequent to the Crusades. Thus, there is no evidence for bejel in Europe, in spite of clear contact (the mechanism of bejel transmission in children) between warring groups, at least during the Crusades. This supports the hypothesis that bejel is a childhood-acquired disease and apparently cannot be contracted in adulthood.

  4. Advanced complex trait analysis.

    Science.gov (United States)

    Gray, A; Stewart, I; Tenesa, A

    2012-12-01

    The Genome-wide Complex Trait Analysis (GCTA) software package can quantify the contribution of genetic variation to phenotypic variation for complex traits. However, as those datasets of interest continue to increase in size, GCTA becomes increasingly computationally prohibitive. We present an adapted version, Advanced Complex Trait Analysis (ACTA), demonstrating dramatically improved performance. We restructure the genetic relationship matrix (GRM) estimation phase of the code and introduce the highly optimized parallel Basic Linear Algebra Subprograms (BLAS) library combined with manual parallelization and optimization. We introduce the Linear Algebra PACKage (LAPACK) library into the restricted maximum likelihood (REML) analysis stage. For a test case with 8999 individuals and 279,435 single nucleotide polymorphisms (SNPs), we reduce the total runtime, using a compute node with two multi-core Intel Nehalem CPUs, from ∼17 h to ∼11 min. The source code is fully available under the GNU Public License, along with Linux binaries. For more information see http://www.epcc.ed.ac.uk/software-products/acta. a.gray@ed.ac.uk Supplementary data are available at Bioinformatics online.

  5. Quantitative traits and diversification.

    Science.gov (United States)

    FitzJohn, Richard G

    2010-12-01

    Quantitative traits have long been hypothesized to affect speciation and extinction rates. For example, smaller body size or increased specialization may be associated with increased rates of diversification. Here, I present a phylogenetic likelihood-based method (quantitative state speciation and extinction [QuaSSE]) that can be used to test such hypotheses using extant character distributions. This approach assumes that diversification follows a birth-death process where speciation and extinction rates may vary with one or more traits that evolve under a diffusion model. Speciation and extinction rates may be arbitrary functions of the character state, allowing much flexibility in testing models of trait-dependent diversification. I test the approach using simulated phylogenies and show that a known relationship between speciation and a quantitative character could be recovered in up to 80% of the cases on large trees (500 species). Consistent with other approaches, detecting shifts in diversification due to differences in extinction rates was harder than when due to differences in speciation rates. Finally, I demonstrate the application of QuaSSE to investigate the correlation between body size and diversification in primates, concluding that clade-specific differences in diversification may be more important than size-dependent diversification in shaping the patterns of diversity within this group.

  6. 12 CFR 583.1 - Acquire.

    Science.gov (United States)

    2010-01-01

    ... AND LOAN HOLDING COMPANIES § 583.1 Acquire. The term acquire means to acquire, directly or indirectly, ownership or control through an acquisition of shares, an acquisition of assets or assumption of liabilities, a merger or consolidation, or any similar transaction....

  7. Evaluation of Aegilops tauschii and Aegilops speltoides for acquired thermotolerance: Implications in wheat breeding programmes.

    Science.gov (United States)

    Hairat, Suboot; Khurana, Paramjit

    2015-10-01

    Severe and frequent heat waves are predicted in the near future having dramatic and far-reaching ecological and social impact. The aim of this study was to examine acquired thermotolerance of two Aegilops species: Aegilops tauschii and Aegilops speltoides and study their potential adaptive mechanisms. The effect of two episodes of high heat stress (45 °C/12 h) with a day of recovery period was investigated on their physiology. As compared to A. speltoides, A. tauschii suffered less inhibition of photosystem II efficiency and net photosynthetic rate (Pn). Although A. tauschii showed nearly complete recovery of PSII, the adverse effect was more pronounced in A. speltoides. Measurement of the minimum fluorescence (Fo) versus temperature curves revealed a higher inflection temperature of Fo for A. tauschii than A. speltoides, reflecting greater thermo stability of the photosynthetic apparatus. Absorbed light energy distribution revealed that A. speltoides showed increased steady state fluorescence and a lower absorbed light allocated to photosynthetic chemistry (ɸPSII) relative to A. tauschii. However, A. tauschii showed higher ability to scavenge free radicals as compared to A. speltoides. This was further validated by higher expression of ascorbate peroxidase gene. These results suggest that A. tauschii showed faster recovery and a better thermostability of its photosynthetic apparatus under severe stress conditions along with a better regulation of energy channeling of PSII complexes to minimize oxidative damage and thus retains greater capability of carbon assimilation. These factors aid in imparting a greater heat tolerance to A. tauschii as compared to A. speltoides and thus make it a better candidate for alien species introgression in wheat breeding programs for thermotolerance in wheat.

  8. Clinorotation affects mesophyll photosynthetic cells in leaves of pea seedlings.

    Science.gov (United States)

    Adamchuk, N I

    1998-07-01

    Experiments with autotrophs in altered gravity condition have a grate significant for development of space biology. The main results of investigation in the photosynthetic apparatus state under microgravity condition have based on the experiments with maturity plants and their differentiated cells. The structural and functional organization of photosynthetic cells in seedlings is poor understandable still. Along with chloroplasts preserving a native membrane system in palisade parenchyma cells of the 29-day pea plant leaves in microgravity, chloroplasts with fribly packed or damaged granae, whose thylakoids appeared as vesicles with an electrontransparent content, were also observed. The investigation of preceding process induced these effects have a sense. That is why, the goal of our experiments was to perform the study of a structural organization of the photosynthetic cells of 3-d pair of pea seedlings leaves under the influence of clinorotation.

  9. Photovoltaic concepts inspired by coherence effects in photosynthetic systems

    Science.gov (United States)

    Brédas, Jean-Luc; Sargent, Edward H.; Scholes, Gregory D.

    2017-01-01

    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.

  10. 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.

  11. Treatment of Chinese Traditional Medicine Wastewater by Photosynthetic Bacteria

    Institute of Scientific and Technical Information of China (English)

    WANG You-zhi; WANG Feng-jun; BAO Li

    2005-01-01

    The influence factors treating wastewater of Chinese traditional medicine extraction by photosynthetic bacteria are tested and discussed. The results indicate that the method of photosynthetic bacteria can eliminate COD and BCD from wastewater in high efficiency. And it also has high load shock resistance. On the conditions of slight aerobic and semi-darkness, treating wastewater of Chinese traditional medicine extraction, the method has better efficiency to eliminate COD and BOD from the wastewater than those by anaerobic illumination and aerobic darkness treatments. After pretreatment of hydrolytic acidization, the removal rate of COD in the wastewater reached more than 85 %, and that rate of BOD reached more than 90% in the treating system of photosynthetic bacteria. It may be more feasible and advantageous than traditional anaerobic biological process to treat organic wastewater using PSB system.

  12. 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.

  13. [Effects of soil phosphorus level on morphological and photosynthetic characteristics of Ageratina adenophora and chromolaena odorata].

    Science.gov (United States)

    Wang, Manlia; Feng, Yulong; Li, Xin

    2006-04-01

    In this paper, a comparative study was made on the growth, morphology, biomass allocation, and photosynthesis of two invasive plant species Ageratina adenophora and Chromolaena odorata under five soil phosphorus levels, aimed to know how the test plant species acclimate to the changes of soil phosphorus level, evaluate which plant traits were associated with the invasiveness of the two species, and know whether the increased level of soil phosphorus could facilitate their invasion. The results showed that the two species had considerable phenotypic plasticity and ? phosphorus acclimation ability. At low phosphorus levels, their root mass ratio increased, which could enhance the nutrient capture ability, while at high phosphorus levels, their specific leaf area, maximum net photosynthetic rate, light saturation point, and chlorophyll and carotenoid contents per unit area were high, and the assimilative capacity and area increased, which could facilitate their carbon gain. A. adenophora had higher phosphorus acclimation ability than C. odorata. With the increase of phosphorous level, the relative growth rate, total biomass, branch number, leaf area index, and maximum net photosynthetic rate of the two species increased significantly, and most of the parameters were not decreased significantly under over-optimal phosphorus level. The two species could grow better under high phosphorus levels which were usually excessive and/or harmful for most native species, and enhanced soil phosphorus level might promote their invasion. At high phosphorus levels, the two invasive plant species might shade out native species through increasing their plant height, branch number, and leaf area index. The two species could maintain relatively high growth rate under high phosphorus levels in dry season when native plant species almost stopped growing. The ability that the invasive plant species could temporally use natural resources which native plant species could not use was also

  14. 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.

  15. Enhanced Practical Photosynthetic CO2 Mitigation

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-07-22

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 4/2/2003 through 7/01/2003. As indicated in the list of accomplishments below we have completed some long-term model scale bioreactor tests and are prepared to begin pilot scale bioreactor testing. Specific results and accomplishments for the second quarter of 2003 include: (1) Bioreactor support systems and test facilities: (a) Qualitative long-term survivability tests for S.C.1.2(2) on Omnisil have been successfully completed and results demonstrate a growth rate that appears to be acceptable. (b) Quantitative tests of long-term growth productivity for S.C.1.2(2) on Omnisil have been completed and initial results are promising. Initial results show that the mass of organisms doubled (from 54.9 grams to 109.8 grams) in about 5 weeks. Full results will be available as soon as all membranes and filters are completely dried. The growth rate should increase significantly with the initiation of weekly harvesting during the long term tests. (c) The phase 1 construction of the pilot scale bioreactor has been completed, including the solar collector and light distribution system. We are now in the phase of system improvement as we wait for CRF-2 results in order to be able to finalize the design and construction of the pilot scale system. (d) A mass transfer experimental setup was constructed in order to measure the mass transfer rate from the gas to the liquid film flowing over a membrane and to study the hydrodynamics of the liquid film flowing over a membrane in the bioreactor. Results were reported for mass transfer coefficient, film thickness, and fluid velocity over an Omnisil membrane with a ''drilled hole'' header pipe design. (2) Organisms and Growth Surfaces: (a) A selectivity approach was used to obtain a cyanobacterial culture with elevated resistance to acid pH. Microlonies of ''3

  16. 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

  17. 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

    2001-10-15

    This report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 10/03/2000 through 10/02/2001. Most of the achievements are milestones in our efforts to complete the tasks and subtasks that constitute the project objectives. This is the fourth quarterly report for this project, so it also serves as a year-1 project review. We have made significant progress on our Phase I objectives, and our current efforts are focused on fulfilling these research objectives ''on time'' relative to the project timeline. Overall, we believe that we are on schedule to complete Phase I activities by 10/2002, which is the milestone date from the original project timeline. Our results to date concerning the individual factors which have the most significant effect on CO{sub 2} uptake are inconclusive, but we have gathered useful information about the effects of lighting, temperature and CO{sub 2} concentration on one particular organism (Nostoc) and significant progress has been made in identifying other organisms that are more suitable for use in the bioreactor due to their better tolerance for the high temperatures likely to be encountered in the flue gas stream. Our current tests are focused on one such thermophilic organism (Cyanidium), and an enlarged bioreactor system (CRF-2) has been prepared for testing this organism. Tests on the enhanced mass transfer CO{sub 2} absorption technique are underway and useful information is currently being collected concerning pressure drop. The solar collectors for the deep-penetration hybrid solar lighting system have been designed and a single solar collector tracking unit is being prepared for installation in the pilot scale bioreactor system currently under construction. Much progress has been made in designing the fiber optic light delivery system, but final selection of the ''optimum'' delivery system design depends on many

  18. Functional traits enhance invasiveness of bamboos over co-occurring tree saplings in the semideciduous Atlantic Forest

    Science.gov (United States)

    Montti, Lía; Villagra, Mariana; Campanello, Paula I.; Gatti, M. Genoveva; Goldstein, Guillermo

    2014-01-01

    Many woody bamboo species are forest understory plants that become invasive after disturbance. They can grow rapidly forming a dense, nearly monospecific understory that inhibits tree regeneration. The principal aim of this study was to understand what functional traits of bamboos allow them to outcompete tree seedlings and saplings and become successful species in the semideciduous Atlantic Forests of northeastern Argentina. We studied leaf and whole-plant functional traits of two bamboo species of the genus Chusquea and five co-occurring saplings of common tree species growing under similar solar radiation and soil nutrient availabilities. Nutrient addition had no effect on bamboo or tree sapling survival and growth after two years. Tree species with high-light requirements had higher growth rates and developed relatively thin leaves with high photosynthetic capacity per unit leaf area and short leaf life-span when growing in gaps, but had lower survival rates in the understory. The opposite pattern was observed in shade-tolerant species that were able to survive in the understory but had lower photosynthetic capacity and growth than light-requiring species in gaps. Bamboos exhibited a high plasticity in functional traits and leaf characteristics that enabled them to grow rapidly in gaps (e.g., higher photosynthetic capacity per unit dry mass and clonal reproduction in gaps than in the understory) but at the same time to tolerate closed-canopy conditions (they had thinner leaves and a relatively longer leaf life-span in the understory compared to gaps). Photosynthetic capacity per unit dry mass was higher in bamboos than in trees. Bamboo plasticity in key functional traits, such as clonal reproduction at the plant level and leaves with a relatively low C cost and high photosynthesis rates, allows them to colonize disturbed forests with consequences at the community and ecosystem levels. Increasing disturbance in some forests worldwide will likely enhance bamboo

  19. Inherited or acquired metabolic disorders.

    Science.gov (United States)

    Eichler, Florian; Ratai, Eva; Carroll, Jason J; Masdeu, Joseph C

    2016-01-01

    This chapter starts with a description of imaging of inherited metabolic disorders, followed by a discussion on imaging of acquired toxic-metabolic disorders of the adult brain. Neuroimaging is crucial for the diagnosis and management of a number of inherited metabolic disorders. Among these, inherited white-matter disorders commonly affect both the nervous system and endocrine organs. Magnetic resonance imaging (MRI) has enabled new classifications of these disorders that have greatly enhanced both our diagnostic ability and our understanding of these complex disorders. Beyond the classic leukodystrophies, we are increasingly recognizing new hereditary leukoencephalopathies such as the hypomyelinating disorders. Conventional imaging can be unrevealing in some metabolic disorders, but proton magnetic resonance spectroscopy (MRS) may be able to directly visualize the metabolic abnormality in certain disorders. Hence, neuroimaging can enhance our understanding of pathogenesis, even in the absence of a pathologic specimen. This review aims to present pathognomonic brain MRI lesion patterns, the diagnostic capacity of proton MRS, and information from clinical and laboratory testing that can aid diagnosis. We demonstrate that applying an advanced neuroimaging approach enhances current diagnostics and management. Additional information on inherited and metabolic disorders of the brain can be found in Chapter 63 in the second volume of this series.

  20. Comparative analysis of growth and photosynthetic characteristics of (Populus simonii × P. nigra × (P. nigra × P. simonii hybrid clones of different ploidides.

    Directory of Open Access Journals (Sweden)

    Xiyang Zhao

    Full Text Available To evaluate differences among poplar clones of various ploidies, 12 hybrid poplar clones (P. simonii × P. nigra × (P. nigra × P. simonii with different ploidies were used to study phenotypic variation in growth traits and photosynthetic characteristics. Analysis of variance showed remarkable differences for each of the investigated traits among these clones (P < 0.01. Coefficients of phenotypic variation (PCV ranged from 2.38% to 56.71%, and repeatability ranged from 0.656 to 0.987. The Pn (photosynthetic rate photosynthetic photon flux density (PPFD curves of the 12 clones were S-shaped, but the Pn-ambient CO2 (Ca curves were shaped like an inverted "V". The stomatal conductance (Gs-PPFD and transpiration rate (Tr-PPFD curves had an upward tendency; however, with increasing PFFD, the intercellular CO2 concentration (Ci-PPFD curves had a downward tendency in all of the clones. The Pn-PPFD and Pn-Ca curves followed the pattern of a quadratic equation. The average light saturation point and light compensation point of the triploid clones were the highest and lowest, respectively, among the three types of clones. For Pn-Ca curves, diploid clones had a higher average CO2 saturation point and average CO2 compensation point compared with triploid and tetraploid clones. Correlation analyses indicated that all investigated traits were strongly correlated with each other. In future studies, molecular methods should be used to analyze poplar clones of different ploidies to improve our understanding of the growth and development mechanisms of polyploidy.

  1. Defects of colour vision: A review of congenital and acquired colour vision deficiencies

    Directory of Open Access Journals (Sweden)

    Nabeela Hasrod

    2016-03-01

    Full Text Available Colour vision deficiencies (CVDs can be categorised as being congenital or acquired. Some CVDs are already present at birth, as inherited conditions that are the result of changes at the photo-pigment level and are non-pathological, incurable and do not change over time. Examples are red-green defects which are inherited as an X-linked recessive trait. Acquired CVD develops secondary to ocular and systemic conditions or as a side effect of certain medications or sometimes toxic effects of chemicals, and trauma and ageing can also be important in some CVDs.

  2. Towards a universal trait-based model of terrestrial primary production

    Science.gov (United States)

    Wang, H.; Prentice, I. C.; Cornwell, W.; Keenan, T. F.; Davis, T.; Wright, I. J.; Evans, B. J.; Peng, C.

    2015-12-01

    Systematic variations of plant traits along environmental gradients have been observed for decades. For example, the tendencies of leaf nitrogen per unit area to increase, and of the leaf-internal to ambient CO2 concentration ratio (ci:ca) to decrease, with aridity are well established. But ecosystem models typically represent trait variation based purely on empirical relationships, or on untested conjectures, or not at all. Neglect of quantitative trait variation and its adapative significance probably contributes to the persistent large uncertainties among models in predicting the response of the carbon cycle to environmental change. However, advances in ecological theory and the accumulation of extensive data sets during recent decades suggest that theoretically based and testable predictions of trait variation could be achieved. Based on well-established ecophysiological principles and consideration of the adaptive significance of traits, we propose universal relationships between photosynthetic traits (ci:ca, carbon fixation capacity, and the ratio of electron transport capacity to carbon fixation capacity) and primary environmental variables, which capture observed trait variations both within and between plant functional types. Moreover, incorporating these traits into the standard model of C3photosynthesis allows gross primary production (GPP) of natural vegetation to be predicted by a single equation with just two free parameters, which can be estimated from independent observations. The resulting model performs as well as much more complex models. Our results provide a fresh perspective with potentially high reward: the possibility of a deeper understanding of the relationships between plant traits and environment, simpler and more robust and reliable representation of land processes in Earth system models, and thus improved predictability for biosphere-atmosphere interactions and climate feedbacks.

  3. 17 CFR 210.8-04 - Financial statements of businesses acquired or to be acquired.

    Science.gov (United States)

    2010-04-01

    ... businesses acquired or to be acquired. (a) If a business combination has occurred or is probable, financial... section. The required financial statements of related businesses may be presented on a combined basis for... financial statements of the business acquired or to be acquired and the smaller reporting company's...

  4. 17 CFR 210.8-06 - Real estate operations acquired or to be acquired.

    Science.gov (United States)

    2010-04-01

    ... 17 Commodity and Securities Exchanges 2 2010-04-01 2010-04-01 false Real estate operations acquired or to be acquired. 210.8-06 Section 210.8-06 Commodity and Securities Exchanges SECURITIES AND... Statements of Smaller Reporting Companies § 210.8-06 Real estate operations acquired or to be acquired. If...

  5. 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. A

  6. 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. A

  7. Photosynthetic bacteria as alternative energy sources: overview on hydrogen production research

    Energy Technology Data Exchange (ETDEWEB)

    Mitsui, A.; Ohta, Y.; Frank, J.

    1979-01-01

    Hydrogen production research towards the application of marine and non-marine species of photosynthetic bacteria is reviewed. Potential use of photosynthetic bacteria as renewable energy resources is discussed.

  8. Effects of Silicon on Photosynthetic Characteristics of Maize (Zea maysL.) on Alluvial Soil

    National Research Council Canada - National Science Library

    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 [subscript] P n [/subscript...

  9. Acquired immune deficiency syndrome: review.

    Science.gov (United States)

    Scully, C; Cawson, R A; Porter, S R

    1986-07-19

    Acquired immunodeficiency syndrome (AIDS) is reviewed for dental practitioners, with an emphasis on oral findings; the clinical course, diagnosis, reporting, treatment, prognosis, transmission, and epidemiology are also covered. HIV infection has an incubation period that may be associated with glandular fever, a prodrome called AIDS-Related Complex (ARC) characterized by lymphadenopathy, low fever, weight loss, night sweats, diarrhea, oral candidosis, nonproductive cough and recurrent infections. AIDS is characterized by opportunistic infections. Over 50% present with pneumocystis carinii pneumonia, 21% with Kaposi's sarcoma, and 6% have both. The AIDS virus causes direct neurological symptoms in some cases. Oral candidosis (thrush) in a young male without a local cause such as xerostomia or immune suppression is strongly suggestive of AIDS. Other oral manifestations are severe herpes simplex, varicella-zoster, Epstein-Barr virus, cytomegalovirus, venereal warts, aphthous ulceration, mycobacterial oral ulcers, oral histoplasmosis, sinusitis and osteomyelitis of the jaw. Hairy leukoplakia, usually seen on the lateral border of the tongue, is probably caused by Epstein-Barr virus. Kaposi's sarcoma, an endothelial cell tumor, is characteristic of AIDS, and in 50% of patients is oral or perioral. Cervical lymph node enlargement will be seen in those with ARC as well as AIDS. No guidelines have been issued by the Department of Health and Social Security for dental surgeons in the UK for reporting AIDS cases. Although HIV virions have been isolated from saliva, there are no known incidents of transmission via saliva. HIV is less likely to be transmitted by needle stick injuries than, for example hepatitis B (25% risk), especially if the blood is from a carrier rather than a full blown AIDS case.

  10. Personality Traits and Social Inequality

    OpenAIRE

    2015-01-01

    During many decades, sociologists have downplayed the role that personality traits play in shaping individual’s lives. However, recent studies, mostly in economics, have shown the influence of these traits on a several educational and occupational outcomes. This thesis is an attempt to shed more light on this topic. By using longitudinal data from the German Socio-Economic Panel, it first investigates how the Big Five personality traits affect two important labor market outcomes: unemployment...

  11. Variability of anatomical-physiological traits in black locust clones - Robinia pseudoacacia L

    Directory of Open Access Journals (Sweden)

    Orlović Saša S.

    2004-01-01

    Full Text Available Variability within R. pseudoacacia species represents an important factor in selection of fast-growing genotypes. Therefore, it is important to identify superior individuals according to their anatomical and physiological traits. This paper presents the results of a study of genotype variability of the main leaf anatomical (frequency, length and width of stomata, leaflet thickness among veins, leaflet thickness on the main vein, mesophyll thickness, length and width of vascular bundle of main vein and physiological (leaf area, photosynthetic pigments content and content of N P, K, Ca, Na parameters among five clones of Robinia pseudoacacia L. Significant interclonal variations were observed in the investigated parameters. Clone R-56 had the highest N, P, and K concentrations, the largest mesophyll volume and the highest pigment concentration. We concluded that the clone R-56, although without a remarkable leaf area, possesses the ability for high photosynthetic production. The results are going to be used in further work on selection.

  12. Protein structure, electron transfer and evolution of prokaryotic photosynthetic reaction centers

    Science.gov (United States)

    Blankenship, R. E.

    1994-01-01

    Photosynthetic reaction centers from a variety of organisms have been isolated and characterized. The groups of prokaryotic photosynthetic organisms include the purple bacteria, the filamentous green bacteria, the green sulfur bacteria and the heliobacteria as anoxygenic representatives as well as the cyanobacteria and prochlorophytes as oxygenic representatives. This review focuses on structural and functional comparisons of the various groups of photosynthetic reaction centers and considers possible evolutionary scenarios to explain the diversity of existing photosynthetic organisms.

  13. Protein structure, electron transfer and evolution of prokaryotic photosynthetic reaction centers

    Science.gov (United States)

    Blankenship, R. E.

    1994-01-01

    Photosynthetic reaction centers from a variety of organisms have been isolated and characterized. The groups of prokaryotic photosynthetic organisms include the purple bacteria, the filamentous green bacteria, the green sulfur bacteria and the heliobacteria as anoxygenic representatives as well as the cyanobacteria and prochlorophytes as oxygenic representatives. This review focuses on structural and functional comparisons of the various groups of photosynthetic reaction centers and considers possible evolutionary scenarios to explain the diversity of existing photosynthetic organisms.

  14. Hybridization of cloned Rhodopseudomonas capsulata photosynthesis genes with DNA from other photosynthetic bacteria.

    OpenAIRE

    Beatty, J T; Cohen, S N

    1983-01-01

    The homology of Rhodopseudomonas capsulata DNA segments carrying photosynthesis genes with sequences present in total DNA from certain other photosynthetic and non-photosynthetic bacterial species was determined by hybridization. R. capsulata DNA fragments that carry loci for production of peptide components of the photosynthetic reaction center and light-harvesting I antenna complex were found to hybridize to DNA from some photosynthetic species. However, fragments that carry carotenoid or b...

  15. Towards improved quantification of vegetation photosynthetic activity at global scale: the FLuorescence EXplorer (FLEX) mission

    Science.gov (United States)

    Moreno, Jose

    2014-05-01

    The fluorescence signal, originated from the core complexes of the photosynthetic machinery, is a sensitive indicator of the actual photosynthesis in both healthy and physiologically stressed vegetation, which can be used as a powerful non-invasive marker to track the status, resilience, and recovery of photochemical processes. This is of particular interest for the improvements in the predictive capability of global carbon cycle models through new parameterizations for canopy photosynthesis and the corresponding exchange processes of energy, water and carbon between the surface and the atmosphere. The shape of the fluorescence emission spectrum consists of two peaks having broad bands with maxima around 685 nm and 740 nm. The variations in amplitude and shape of the emission reflect the efficiency of photosynthetic electron transport. The integral of the overall fluorescence emission provides information about actual photosynthetic light conversion. The shape of the emission spectrum provides additional information about the vegetation health status. While most of the information that has been acquired by remote sensing of the Earth's surface about vegetation conditions and photosynthetic activity has come from "reflected" light in the solar domain, the ESA's Earth Explorer candidate FLEX (Fluorescence EXplorer) mission is the first space mission focused on the estimation of fluorescence emission by terrestrial vegetation on a global scale with high spatial resolution and resolving the spectral shape of fluorescence emission. The FLEX mission also includes explicit measurement of photochemical changes in reflectance (i.e., PRI), canopy temperature measurements and all the relevant variables (chlorophyll content, Leaf Area Index, etc.) needed to asses the actual physiological status of vegetation and to provide quantitative estimates of photosynthetic rates and gross primary production. FLEX is one of two candidate Earth Explorer-8 missions currently under Phase A

  16. 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) 4....... sphaeroides was around 35% of dry cell weight, mainly composed of vaccenic acid (C18:1, omega-7)....

  17. Photosynthetic terpene hydrocarbon production for fuels and chemicals

    Science.gov (United States)

    Photosynthetic terpene production[ED1] represents an energy and carbon-efficient route for hydrocarbon fuel production. Diverse terpene structures also provide the potential to produce next-generation 'drop-in' hydrocarbon fuel molecules. However, it is highly challenging to achieve efficient redire...

  18. Modeling the dynamic modulation of light energy in photosynthetic algae.

    Science.gov (United States)

    Papadakis, Ioannis A; Kotzabasis, Kiriakos; Lika, Konstadia

    2012-05-01

    An integrated cell-based dynamic mathematical model that take into account the role of the photon absorbing process, the partition of excitation energy, and the photoinactivation and repair of photosynthetic units, under variable light and dissolved inorganic carbon (DIC) availability is proposed. The modeling of the photon energy absorption and the energy dissipation is based on the photoadaptive changes of the underlying mechanisms. The partition of the excitation energy is based on the relative availability of light and DIC to the cell. The modeling of the photoinactivation process is based on the common aspect that it occurs under any light intensity and the modeling of the repair process is based on the evidence that it is controlled by chloroplast and nuclear-encoded enzymes. The present model links the absorption of photons and the partitioning of excitation energy to the linear electron flow and other quenchers with chlorophyll fluorescence emission parameters, and the number of the functional photosynthetic units with the photosynthetic oxygen production rate. The energy allocation to the LEF increases as DIC availability increases and/or light intensity decreases. The rate of rejected energy increases with light intensity and with DIC availability. The resulting rate coefficient of photoinactivation increases as light intensity and/or as DIC concentration increases. We test the model against chlorophyll fluorescence induction and photosynthetic oxygen production rate measurements, obtained from cultures of the unicellular green alga Scenedesmus obliquus, and find a very close quantitative and qualitative correspondence between predictions and data.

  19. Hydraulic constraints modify optimal photosynthetic profiles in giant sequoia trees.

    Science.gov (United States)

    Ambrose, Anthony R; Baxter, Wendy L; Wong, Christopher S; Burgess, Stephen S O; Williams, Cameron B; Næsborg, Rikke R; Koch, George W; Dawson, Todd E

    2016-11-01

    Optimality theory states that whole-tree carbon gain is maximized when leaf N and photosynthetic capacity profiles are distributed along vertical light gradients such that the marginal gain of nitrogen investment is identical among leaves. However, observed photosynthetic N gradients in trees do not follow this prediction, and the causes for this apparent discrepancy remain uncertain. Our objective was to evaluate how hydraulic limitations potentially modify crown-level optimization in Sequoiadendron giganteum (giant sequoia) trees up to 90 m tall. Leaf water potential (Ψ l ) and branch sap flow closely followed diurnal patterns of solar radiation throughout each tree crown. Minimum leaf water potential correlated negatively with height above ground, while leaf mass per area (LMA), shoot mass per area (SMA), leaf nitrogen content (%N), and bulk leaf stable carbon isotope ratios (δ(13)C) correlated positively with height. We found no significant vertical trends in maximum leaf photosynthesis (A), stomatal conductance (g s), and intrinsic water-use efficiency (A/g s), nor in branch-averaged transpiration (E L), stomatal conductance (G S), and hydraulic conductance (K L). Adjustments in hydraulic architecture appear to partially compensate for increasing hydraulic limitations with height in giant sequoia, allowing them to sustain global maximum summer water use rates exceeding 2000 kg day(-1). However, we found that leaf N and photosynthetic capacity do not follow the vertical light gradient, supporting the hypothesis that increasing limitations on water transport capacity with height modify photosynthetic optimization in tall trees.

  20. Systemic regulation of photosynthetic function in field-grown sorghum.

    Science.gov (United States)

    Li, Tao; Liu, Yujun; Shi, Lei; Jiang, Chuangdao

    2015-09-01

    The photosynthetic characteristics of developing leaves of plants grown under artificial conditions are, to some extent, regulated systemically by mature leaves; however, whether systemic regulation of photosynthesis occurs in field-grown crops is unclear. To explore this question, we investigated the effects of planting density on growth characteristics, gas exchange, leaf nitrogen concentration and chlorophyll a fluorescence in field-grown sorghum (Sorghum bicolor L.). Our results showed that close planting resulted in a marked decline in light intensity in lower canopy. Sorghum plants grown at a high planting density had lower net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (E) than plants grown at a low planting density. Moreover, in the absence of mineral deficiency, close planting induced a slight increase in leaf nitrogen concentration. The decreased photosynthesis in leaves of the lower canopy at high planting density was caused mainly by the low light. However, newly developed leaves exposed to high light in the upper canopy of plants grown at high planting density also exhibited a distinct decline in photosynthesis relative to plants grown at low planting density. Based on these results, the photosynthetic function of the newly developed leaves in the upper canopy was not determined fully by their own high light environment. Accordingly, we suggest that the photosynthetic function of newly developed leaves in the upper canopy of field-grown sorghum plants is regulated systemically by the lower canopy leaves. The differences in systemic regulation of photosynthesis were also discussed between field conditions and artificial conditions.

  1. Functional Implications of Photosystem II Crystal Formation in Photosynthetic Membranes*

    Science.gov (United States)

    Tietz, Stefanie; Puthiyaveetil, Sujith; Enlow, Heather M.; Yarbrough, Robert; Wood, Magnus; Semchonok, Dmitry A.; Lowry, Troy; Li, Zhirong; Jahns, Peter; Boekema, Egbert J.; Lenhert, Steven; Niyogi, Krishna K.; Kirchhoff, Helmut

    2015-01-01

    The structural organization of proteins in biological membranes can affect their function. Photosynthetic thylakoid membranes in chloroplasts have the remarkable ability to change their supramolecular organization between disordered and semicrystalline states. Although the change to the semicrystalline state is known to be triggered by abiotic factors, the functional significance of this protein organization has not yet been understood. Taking advantage of an Arabidopsis thaliana fatty acid desaturase mutant (fad5) that constitutively forms semicrystalline arrays, we systematically test the functional implications of protein crystals in photosynthetic membranes. Here, we show that the change into an ordered state facilitates molecular diffusion of photosynthetic components in crowded thylakoid membranes. The increased mobility of small lipophilic molecules like plastoquinone and xanthophylls has implications for diffusion-dependent electron transport and photoprotective energy-dependent quenching. The mobility of the large photosystem II supercomplexes, however, is impaired, leading to retarded repair of damaged proteins. Our results demonstrate that supramolecular changes into more ordered states have differing impacts on photosynthesis that favor either diffusion-dependent electron transport and photoprotection or protein repair processes, thus fine-tuning the photosynthetic energy conversion. PMID:25897076

  2. Functional Implications of Photosystem II Crystal Formation in Photosynthetic Membranes.

    Science.gov (United States)

    Tietz, Stefanie; Puthiyaveetil, Sujith; Enlow, Heather M; Yarbrough, Robert; Wood, Magnus; Semchonok, Dmitry A; Lowry, Troy; Li, Zhirong; Jahns, Peter; Boekema, Egbert J; Lenhert, Steven; Niyogi, Krishna K; Kirchhoff, Helmut

    2015-05-29

    The structural organization of proteins in biological membranes can affect their function. Photosynthetic thylakoid membranes in chloroplasts have the remarkable ability to change their supramolecular organization between disordered and semicrystalline states. Although the change to the semicrystalline state is known to be triggered by abiotic factors, the functional significance of this protein organization has not yet been understood. Taking advantage of an Arabidopsis thaliana fatty acid desaturase mutant (fad5) that constitutively forms semicrystalline arrays, we systematically test the functional implications of protein crystals in photosynthetic membranes. Here, we show that the change into an ordered state facilitates molecular diffusion of photosynthetic components in crowded thylakoid membranes. The increased mobility of small lipophilic molecules like plastoquinone and xanthophylls has implications for diffusion-dependent electron transport and photoprotective energy-dependent quenching. The mobility of the large photosystem II supercomplexes, however, is impaired, leading to retarded repair of damaged proteins. Our results demonstrate that supramolecular changes into more ordered states have differing impacts on photosynthesis that favor either diffusion-dependent electron transport and photoprotection or protein repair processes, thus fine-tuning the photosynthetic energy conversion.

  3. 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 extracting pigments by a…

  4. Effect of Pb2+ ions on photosynthetic apparatus.

    Science.gov (United States)

    Sersen, Frantisek; Kralova, Katarina; Pesko, Matus; Cigan, Marek

    2014-01-01

    Using model lead compounds Pb(NO3)2 and Pb(CH3CHOO)2, the mechanism and the site of action of Pb2+ ions in the photosynthetic apparatus of spinach chloroplasts were studied. Both compounds inhibited photosynthetic electron transport (PET) through photosystem 1 (PS1) and photosystem 2 (PS2), while Pb(NO3)2 was found to be more effective PET inhibitor. Using EPR spectroscopy the following sites of Pb2+ action in the photosynthetic apparatus were determined: the water-splitting complex and the Z•/D• intermediates on the donor side of PS2 and probably also the ferredoxin on the acceptor side of PS1, because cyclic electron flow in chloroplasts was impaired by treatment with Pb2+ ions. Study of chlorophyll fluorescence in suspension of spinach chloroplasts in the presence of Pb2+ ions confirmed their site of action in PS2. Using fluorescence spectroscopy also formation of complexes between Pb2+ and amino acid residues in photosynthetic proteins was confirmed and constants of complex formation among Pb2+ and aromatic amino acids were calculated for both studied lead compounds.

  5. 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

  6. Intraspecific Trait Variation and Coordination: Root and Leaf Economics Spectra in Coffee across Environmental Gradients.

    Science.gov (United States)

    Isaac, Marney E; Martin, Adam R; de Melo Virginio Filho, Elias; Rapidel, Bruno; Roupsard, Olivier; Van den Meersche, Karel

    2017-01-01

    Hypotheses on the existence of a universal "Root Economics Spectrum" (RES) have received arguably the least attention of all trait spectra, despite the key role root trait variation plays in resource acquisition potential. There is growing interest in quantifying intraspecific trait variation (ITV) in plants, but there are few studies evaluating (i) the existence of an intraspecific RES within a plant species, or (ii) how a RES may be coordinated with other trait spectra within species, such as a leaf economics spectrum (LES). Using Coffea arabica (Rubiaceae) as a model species, we measured seven morphological and chemical traits of intact lateral roots, which were paired with information on four key LES traits. Field collections were completed across four nested levels of biological organization. The intraspecific trait coefficient of variation (cv) ranged from 25 to 87% with root diameter and specific root tip density showing the lowest and highest cv, respectively. Between 27 and 68% of root ITV was explained by site identity alone for five of the seven traits measured. A single principal component explained 56.2% of root trait covariation, with plants falling along a RES from resource acquiring to conserving traits. Multiple factor analysis revealed significant orthogonal relationships between root and leaf spectra. RES traits were strongly orthogonal with respect to LES traits, suggesting these traits vary independently from one another in response to environmental cues. This study provides among the first evidence that plants from the same species differentiate from one another along an intraspecific RES. We find that in one of the world's most widely cultivated crops, an intraspecific RES is orthogonal to an intraspecific LES, indicating that above and belowground responses of plants to managed (or natural) environmental gradients are likely to occur independently from one another.

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

    OpenAIRE

    Minobu Kasai; Keisuke Koide; Yuya Ichikawa

    2012-01-01

    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, implica...

  8. Hydrogen peroxide inhibits photosynthetic electron transport in cells of cyanobacteria.

    Science.gov (United States)

    Samuilov, V D; Bezryadnov, D B; Gusev, M V; Kitashov, A V; Fedorenko, T A

    2001-06-01

    The effect of H2O2 on photosynthetic O2 evolution and photosynthetic electron transfer in cells of cyanobacteria Anabaena variabilis and Anacystis nidulans was studied. The following experiments were performed: 1) directly testing the effect of exogenous H2O2; 2) testing the effect of intracellular H2O2 generated with the use of methyl viologen (MV); 3) testing the effect of inhibiting intracellular H2O2 decomposition by salicylic acid (SA) and 3-amino-1,2,4-triazole (AT). H2O2 inhibited photosynthetic O2 evolution and light-induced reduction of p-benzoquinone (BQ) + ferricyanide (FeCy) in the Hill reaction. The I50 value for H2O2 was ~0.75 mM. Photosynthetic electron transfer in the cells treated with H2O2 was not maintained by H2O2, NH2OH, 1,5-diphenylcarbazide, tetraphenylboron, or butylated hydroxytoluene added as artificial electron donors for Photosystem (PS) II. The H2O --> CO2, H2O --> MV (involving PSII and PSI) and H2O --> BQ + FeCy (chiefly dependent on PSII) electron transfer reactions were inhibited upon incubation of the cells with MV, SA, or AT. The N,N,N,N-tetramethyl-p-phenylenediamine --> MV (chiefly dependent on PSI) electron transfer was inhibited by SA and AT but was resistant to MV. The results show that H2O2 inhibits photosynthetic electron transfer. It is unlikely that H2O2 could be a physiological electron donor in oxygenic photosynthesis.

  9. [Environmental Effect of Substrate Amelioration on Lake: Effects on Phragmites communis Growth and Photosynthetic Fluorescence Characteristics].

    Science.gov (United States)

    Yu, Ju-hua; Zhong, Ji-cheng; Fan, Cheng-xin; Huang, Wei; Shang, Jing-ge; Gu, Xiao-zhi

    2015-12-01

    Growth of rooted aquatic macrophytes was affected by the nature and composition of lake bottom sediments. Obviously, it has been recognized as an important ecological restoration measure by improving lake substrate and then reestablishing and restoring aquatic macrophytes in order to get rid of the environmental problem of lake. This study simulated five covering thickness to give an insight into the influence of substrate amelioration on Phragmites communis growth and photosynthetic fluorescence characteristics. The results showed that the total biomass, plant height, leaf length and leaf width of Phragmites communis under capping 5 cm were much more significant than those of capping 18 cm (P Phragmites communis , but the growth of control group Phragmites communis was slightly constrained by eutrophicated sediment. In addition, as the capping thickness growing, the underground: shoot biomass ratio of the plant would be reduced dramatically, in order to acquire much more nutrients from sediment for plant growing, the underground biomass of Phragmites communis would be preferentially developed, especially, the biomass of fine root. However, Photosystem II (PS II) photochemical efficiency (Fv/Fm), quantum yield (Yield), photochemical quenching (qP), non-photochemical quenching (qN) of Phragmites communis under different treatments had no significant differences (P > 0.05), furthermore, with much greater capping thickness, the photosynthesis structure of PS II would be much easier destroyed, and PS II would be protected by increasing heat dissipating and reducing leaf photosynthetic area and leaf light-captured pigment contents. In terms of the influence of sediment amelioration by soil exchange on the growth and photosynthetic fluorescence characteristics of Phragmites communis, plant growth could be effectively promoted under capping 2 cm and capping 5 cm by increasing the Eh value and nutrient content, whereas plant under capping 18 cm would be much easier

  10. Estimating plant traits of grasslands from UAV-acquired hyperspectral images

    NARCIS (Netherlands)

    Capolupo, Alessandra; Kooistra, Lammert; Berendonk, Clara; Boccia, Lorenzo; Suomalainen, Juha

    2015-01-01

    Grassland ecosystems cover around 40% of the entire Earth's surface. Therefore, it is necessary to guarantee good grassland management at field scale in order to improve its conservation and to achieve optimal growth. This study identified the most appropriate statistical strategy, between

  11. Seasonal succession in zooplankton feeding traits reveals trophic trait coupling

    DEFF Research Database (Denmark)

    Kenitz, Kasia; Visser, Andre; Mariani, Patrizio

    2017-01-01

    succession and shows how the physical environment controls the vertical structure of plankton communities, where ambush feeders exhibit a preference for greater depths during summer. We characterize the seasonal succession as trophic trait coupling and conjecture that this coupling leads to a trophic trait......The seasonal forcing of pelagic communities invokes a succession of the dominant phytoplankton and zooplankton species. Here, we characterize the seasonal succession of the plankton traits and their interactions using observations and model simulations of the plankton community in the western...... English Channel. We focus on activity traits that characterize the defensive and feeding abilities of zooplankton and distinguish between low risk, low return ambush feeders and high risk, high return feeding-current feeders. While the phytoplankton succession depends on traits related to nutrient...

  12. Giraffe browsing in response to plant traits

    Science.gov (United States)

    Mahenya, Obeid; Ndjamba, Johannes Kambinda; Mathisen, Karen Marie; Skarpe, Christina

    2016-08-01

    Intake rates by large herbivores are governed by among other things plant traits. We used Masai giraffe (Giraffa camelopardalis tippelskirchi Matschie) as study animals, testing whether they as very large browsers would follow the Jarman-Bell principle and maximize intake rate while tolerating low forage quality. We worked in Arusha National Park, Tanzania. We investigated how intake rate was determined by bite mass and bite rate, and show that bite mass and bite rate were determined by plant characteristics, governed by inherent plant traits, plant traits acquired from previous years' browsing, and season. We predicted that; (1) bite mass would be larger in trees without spines than with (2) bite mass would be larger in the wet season than in the dry, (3) bite rate would be higher in spinescent trees than in non-spinescent, (4) bite rate and/or bite mass would increase with previous years' browsing, (5) bite mass, bite rate or browsing time per tree would be highest for high trees with large, although still available canopies. Visual observations were used to collect data on tree attributes, number of bites taken and time of browsing. Sample size was 132 observed giraffe. We found that bite mass was larger in spineless than in spinescent trees and was larger in the wet season than in the dry. Bite rate, but not bite mass, increased with increasing browsing in previous years and was highest on two to three meter high trees and in spinescent trees. Intake rate followed bite mass more than bite rate and was higher in spineless than in spinescent trees, higher in the wet season than in the dry, and tended to increase with tree height. Giraffe did not prioritize the highest intake rate, but browsed much on Acacias giving a high quality diet but a low intake rate.

  13. Manager traits and quality-of-care performance in hospitals.

    Science.gov (United States)

    Aij, Kjeld Harald; Aernoudts, René L M C; Joosten, Gepke

    2015-07-06

    This paper aims to assess the impact of the leadership traits of chief executive officers (CEOs) on hospital performance in the USA. The effectiveness and efficiency of the CEO is of critical importance to the performance of any organization, including hospitals. Management systems and manager behaviours (traits) are of crucial importance to any organization because of their connection with organizational performance. To identify key factors associated with the quality of care delivered by hospitals, the authors gathered perceptions of manager traits from chief executive officers (CEOs) and followers in three groups of US hospitals delivering different levels of quality of care performance. Three high- and three low-performing hospitals were selected from the top and bottom 20th percentiles, respectively, using a national hospital ranking system based on standard quality of care performance measures. Three lean hospitals delivering intermediate performance were also selected. A survey was used to gather perceptions of manager traits (providing a modern or lean management system inclination) from CEOs and their followers in the three groups, which were compared. Four traits were found to be significantly different (alpha performing hospitals. The different perceptions between these two hospital groups were all held by followers in the low-performing hospitals and not the CEOs, and all had a modern management inclination. No differences were found between lean (intermediate-) and high-performing hospitals, or between high- and low-performing hospitals. These findings support a need for hospital managers to acquire appropriate traits to achieve lean transformation, support a benefit of measuring manager traits to assess progress towards lean transformation and lend weight to improved quality of care that can be delivered by hospitals adopting a lean system of management.

  14. Cryptosporidiosis in the acquired immune deficiency syndrome.

    Science.gov (United States)

    Cooper, D A; Wodak, A; Marriot, D J; Harkness, J L; Ralston, M; Hill, A; Penny, R

    1984-10-01

    Cryptosporidiosis was found in a patient with the acquired immune deficiency syndrome. The microbiological and morphological features of this newly recognized opportunistic infection are distinctive and diagnostic.

  15. Acquired Dyslexia and Dysgraphia in Chinese

    Directory of Open Access Journals (Sweden)

    Wengang Yin

    2005-01-01

    Full Text Available Understanding how the mappings between orthography and phonology in alphabetic languages are learned, represented and processed has been enhanced by the cognitive neuropsychological investigation of patients with acquired reading and writing disorders. During the past decade, this methodology has been extended to understanding reading and writing in Chinese leading to new insights about language processing, dyslexia and dysgraphia. The aim of this paper is to review reports of patients who have acquired dyslexia and acquired dysgraphia in Chinese and describe the functional architecture of the reading and writing system. Our conclusion is that the unique features of Chinese script will determine the symptoms of acquired dyslexia and dysgraphia in Chinese.

  16. 24-epibrassinolide mitigates the adverse effects of manganese induced toxicity through improved antioxidant system and photosynthetic attributes in Brassica juncea.

    Science.gov (United States)

    Fariduddin, Qazi; Ahmed, Mumtaz; Mir, Bilal A; Yusuf, Mohammad; Khan, Tanveer A

    2015-08-01

    The objective of this study was to establish relationship between manganese-induced toxicity and antioxidant system response in Brassica juncea plants and also to investigate whether brassinosteroids activate antioxidant system to confer tolerance to the plants affected with manganese induced oxidative stress. Brassica juncea plants were administered with 3, 6, or 9 mM manganese at 10-day stage for 3 days. At 31-day stage, the seedlings were sprayed with deionized water (control) or 10(-8) M of 24-epibrassinolide, and plants were harvested at 45-day stage to assess growth, leaf gas-exchange traits, and biochemical parameters. The manganese treatments diminished growth along with photosynthetic attributes and carbonic anhydrase activity in the concentration-dependent manner, whereas it enhanced lipid peroxidation, electrolyte leakage, accumulation of H2O2 as well as proline, and various antioxidant enzymes in the leaves of Brassica juncea which were more pronounced at higher concentrations of manganese. However, the follow-up application of 24-epibrassinolide to the manganese stressed plants improved growth, water relations, and photosynthesis and further enhanced the various antioxidant enzymes viz. catalase, peroxidase, and superoxide dismutase and content of proline. The elevated level of antioxidant enzymes as well as proline could have conferred tolerance to the manganese-stressed plants resulting in improved growth and photosynthetic attributes.

  17. Diffusional limitations explain the lower photosynthetic capacity of ferns as compared with angiosperms in a common garden study.

    Science.gov (United States)

    Carriquí, M; Cabrera, H M; Conesa, M À; Coopman, R E; Douthe, C; Gago, J; Gallé, A; Galmés, J; Ribas-Carbo, M; Tomás, M; Flexas, J

    2015-03-01

    Ferns are thought to have lower photosynthetic rates than angiosperms and they lack fine stomatal regulation. However, no study has directly compared photosynthesis in plants of both groups grown under optimal conditions in a common environment. We present a common garden comparison of seven angiosperms and seven ferns paired by habitat preference, with the aims of (1) confirming that ferns do have lower photosynthesis capacity than angiosperms and quantifying these differences; (2) determining the importance of diffusional versus biochemical limitations; and (3) analysing the potential implication of leaf anatomical traits in setting the photosynthesis capacity in both groups. On average, the photosynthetic rate of ferns was about half that of angiosperms, and they exhibited lower stomatal and mesophyll conductance to CO2 (gm ), maximum velocity of carboxylation and electron transport rate. A quantitative limitation analysis revealed that stomatal and mesophyll conductances were co-responsible for the lower photosynthesis of ferns as compared with angiosperms. However, gm alone was the most constraining factor for photosynthesis in ferns. Consistently, leaf anatomy showed important differences between angiosperms and ferns, especially in cell wall thickness and the surface of chloroplasts exposed to intercellular air spaces.

  18. On the number of independent cultural traits carried by individuals and populations

    Science.gov (United States)

    Lehmann, Laurent; Aoki, Kenichi; Feldman, Marcus W.

    2011-01-01

    In species subject to individual and social learning, each individual is likely to express a certain number of different cultural traits acquired during its lifetime. If the process of trait innovation and transmission reaches a steady state in the population, the number of different cultural traits carried by an individual converges to some stationary distribution. We call this the trait-number distribution. In this paper, we derive the trait-number distributions for both individuals and populations when cultural traits are independent of each other. Our results suggest that as the number of cultural traits becomes large, the trait-number distributions approach Poisson distributions so that their means characterize cultural diversity in the population. We then analyse how the mean trait number varies at both the individual and population levels as a function of various demographic features, such as population size and subdivision, and social learning rules, such as conformism and anti-conformism. Diversity at the individual and population levels, as well as at the level of cultural homogeneity within groups, depends critically on the details of population demography and the individual and social learning rules. PMID:21199846

  19. On the number of independent cultural traits carried by individuals and populations.

    Science.gov (United States)

    Lehmann, Laurent; Aoki, Kenichi; Feldman, Marcus W

    2011-02-12

    In species subject to individual and social learning, each individual is likely to express a certain number of different cultural traits acquired during its lifetime. If the process of trait innovation and transmission reaches a steady state in the population, the number of different cultural traits carried by an individual converges to some stationary distribution. We call this the trait-number distribution. In this paper, we derive the trait-number distributions for both individuals and populations when cultural traits are independent of each other. Our results suggest that as the number of cultural traits becomes large, the trait-number distributions approach Poisson distributions so that their means characterize cultural diversity in the population. We then analyse how the mean trait number varies at both the individual and population levels as a function of various demographic features, such as population size and subdivision, and social learning rules, such as conformism and anti-conformism. Diversity at the individual and population levels, as well as at the level of cultural homogeneity within groups, depends critically on the details of population demography and the individual and social learning rules.

  20. Relationships Between Spielberger Trait Anxiety and Lykken Social and Physical Trait Anxiety

    Science.gov (United States)

    Blankstein, Kirk R.

    1976-01-01

    To determine the relationship between Spielberger's measure of trait anxiety and social-interpersonal vs. physical danger trait anxiety, Ss were administered the trait scale of the State-Trait Anxiety Inventory (STAI) and Lykken's Activity Preference Questionnaire (APQ). (Editor)

  1. Coordination of Leaf Photosynthesis, Transpiration, and Structural Traits in Rice and Wild Relatives (Genus Oryza).

    Science.gov (United States)

    Giuliani, Rita; Koteyeva, Nuria; Voznesenskaya, Elena; Evans, Marc A; Cousins, Asaph B; Edwards, Gerald E

    2013-07-01

    The genus Oryza, which includes rice (Oryza sativa and Oryza glaberrima) and wild relatives, is a useful genus to study leaf properties in order to identify structural features that control CO(2) access to chloroplasts, photosynthesis, water use efficiency, and drought tolerance. Traits, 26 structural and 17 functional, associated with photosynthesis and transpiration were quantified on 24 accessions (representatives of 17 species and eight genomes). Hypotheses of associations within, and between, structure, photosynthesis, and transpiration were tested. Two main clusters of positively interrelated leaf traits were identified: in the first cluster were structural features, leaf thickness (Thick(leaf)), mesophyll (M) cell surface area exposed to intercellular air space per unit of leaf surface area (S(mes)), and M cell size; a second group included functional traits, net photosynthetic rate, transpiration rate, M conductance to CO(2) diffusion (g(m)), stomatal conductance to gas diffusion (g(s)), and the g(m)/g(s) ratio.While net photosynthetic rate was positively correlated with gm, neither was significantly linked with any individual structural traits. The results suggest that changes in gm depend on covariations of multiple leaf (S(mes)) and M cell (including cell wall thickness) structural traits. There was an inverse relationship between Thick(leaf) and transpiration rate and a significant positive association between Thick(leaf) and leaf transpiration efficiency. Interestingly, high g(m) together with high g(m)/g(s) and a low S(mes)/g(m) ratio (M resistance to CO(2) diffusion per unit of cell surface area exposed to intercellular air space) appear to be ideal for supporting leaf photosynthesis while preserving water; in addition, thick M cell walls may be beneficial for plant drought tolerance.

  2. Changes in photosynthetic carbon metabolism in senescent leaves of chickpea, Cicer arietinum L.

    Directory of Open Access Journals (Sweden)

    Chandrashekhar V. Murumkar

    2014-01-01

    Full Text Available Photosynthetic processes in mature and senescent leaves of chickpea (Cicer arietinum L. have been compared. With age, leaf photosynthetic pigments viz. chlorophyll a, chlorophyll b and carotenoids, and rate of 14°C fixation were considerably affected. Analysis of δ13C, and short term photosynthetic products showed no major change in the path of photosynthetic carbon fixation. Study of long term photosynthetic 14C assimilation revealed that in old senescent leaves, 14C incorporation into organic acid and sugar fractions was enhanced.

  3. Ontogeny strongly and differentially alters leaf economic and other key traits in three diverse Helianthus species.

    Science.gov (United States)

    Mason, Chase M; McGaughey, Sarah E; Donovan, Lisa A

    2013-10-01

    The leaf economics spectrum (LES) describes large cross-species variation in suites of leaf functional traits ranging from resource-acquisitive to resource-conservative strategies. Such strategies have been integral in explaining plant adaptation to diverse environments, and have been linked to numerous ecosystem processes. The LES has previously been found to be significantly modulated by climate, soil fertility, biogeography, growth form, and life history. One largely unexplored aspect of LES variation, whole-plant ontogeny, is investigated here using multiple populations of three very different species of sunflower: Helianthus annuus, Helianthus mollis, and Helianthus radula. Plants were grown under environmentally controlled conditions and assessed for LES and related traits at four key developmental stages, using recently matured leaves to standardize for leaf age. Nearly every trait exhibited a significant ontogenetic shift in one or more species, with trait patterns differing among populations and species. Photosynthetic rate, leaf nitrogen concentration, and leaf mass per area exhibited surprisingly large changes, spanning over two-thirds of the original cross-species LES variation and shifting from resource-acquisitive to resource-conservative strategies as the plants matured. Other traits being investigated in relation to the LES, such as leaf water content, pH, and vein density, also showed large changes. The finding that ontogenetic variation in LES strategy can be substantial leads to a recommendation of standardization by developmental stage when assessing 'species values' of labile traits for comparative approaches. Additionally, the substantial ontogenetic trait shifts seen within single individuals provide an opportunity to uncover the contribution of gene regulatory changes to variation in LES traits.

  4. Environmental Filtering of Forest Canopy Functional Traits Determined from Imaging Spectroscopy 139618

    Science.gov (United States)

    Asner, G. P.

    2016-12-01

    Forests play a vital role in the functioning of the biosphere, yet little is known about functional properties of forest canopies that contribute to biospheric processes. Forest canopy functional traits - the chemical and physical properties of the foliage mediating carbon update, nutrient use, and water relations - are of particular interest because they link tree physiology to biogeochemical and hydrological cycles. Measuring forest canopy functional traits has been a slow, laborious, and usually spatially biased process. Forest functional traits are difficult to assess because spatial and temporal variation often exceeds our ability to adequately utilize field-based approaches, and traditional satellite observations do not easily reveal functionally-relevant differences or changes. Using high-fidelity imaging spectroscopy, it is possible to measure, map and monitor a growing suite of forest canopy functional traits, including water content, multiple nutrients, photosynthetic pigments, and defense compounds. In combination, these traits describe a large proportion of tree physiology, and the interaction with abiotic and biotic drivers. Using airborne imaging spectroscopy from the Carnegie Airborne Observatory, combined with maps of geophysical, climatic and land-use factors, we have determined the relative importance of these environmental filters in determining forest canopy functional traits over large areas such as the Peruvian Amazon, California, and Borneo. Results indicate consistency in the critical role of certain environmental factors that geographically sort forest canopy functional traits, with multiple secondary factors shifting their contribution among forest types. Mapping and monitoring a suite of forest functional traits is now possible at sub-continental scales using airborne high-fidelity imaging spectroscopy. Taking this new scientific knowledge and capability global will require an Earth observing mission with 15-16 day revisit and a spatial

  5. Response of growth, quality parameters and photosynthetic apparatus of endive plant to different culture media

    Directory of Open Access Journals (Sweden)

    Kowalczyk Katarzyna

    2016-06-01

    Full Text Available Endive (Cichorium endivia L. is a leaf vegetable with high vitamin and nutritional values. Therefore, an increase of its cultivation in Poland and other European countries has been observed in recent years. The aim of this research was to study the effect of different growth media on the quality and photosynthetic efficiency of different endive cultivars. The experiment was conducted in controlled greenhouse conditions. Endive was grown in three independent NFT cultivation systems: a standard culture medium (control, A1, a culture medium concentrated three-fold (A2 and a medium concentrated five-fold (A3. Four cultivars were used: ‘Kethel’, ‘Barundi’, ‘Galanti’ and ‘Perceval’. The plants were examined for the number and weight of fully-grown leaves and the weight of roots, dry matter content and chemical quality attributes of endive such as ascorbic acid (AA, total soluble solids (TSS, chlorophyll and proline. In addition, several physiological traits such as modulated chlorophyll a fluorescence were measured.

  6. Quantitative trait loci underlying udder morphology traits in dairy sheep.

    Science.gov (United States)

    Gutiérrez-Gil, B; El-Zarei, M F; Alvarez, L; Bayón, Y; de la Fuente, L F; San Primitivo, F; Arranz, J J

    2008-09-01

    A genome scan was conducted on the basis of the daughter design to detect quantitative trait loci (QTL) influencing udder morphology traits in Spanish Churra dairy sheep. A total of 739 ewes belonging to 11 half-sib families were genotyped for 182 microsatellite markers covering 3,248.2 cM (Kosambi) of the ovine autosomal genome. Phenotypic traits included scores for 5 linear udder traits: udder depth, udder attachment, teat placement, teat size, and udder shape. Quantitative measurements for the QTL analysis were calculated for each trait from evaluation scores using within-family yield deviations corrected for fixed environmental effects. Joint analysis of all families using Haley-Knott regression identified 5 regions that exceeded the 5% chromosome-wise significance threshold on chromosomes 7, 14, 15, 20, and 26. Based on the across-family results, a within-family analysis was carried out to identify families segregated according to the QTL and to estimate the QTL effect. The allelic substitution effect for individual families ranged from 0.47 to 1.7 phenotypic standard deviation units for udder shape on chromosome 15 and udder depth on chromosome 14, respectively. These QTL regions provide a starting point for further research aimed at the characterization of genetic variability involved in udder traits in Churra sheep. This paper presents the first report of a sheep genome scan for udder-related traits in a dairy sheep outbred population.

  7. Quantitative trait loci underlying milk production traits in sheep.

    Science.gov (United States)

    Gutiérrez-Gil, B; El-Zarei, M F; Alvarez, L; Bayón, Y; de la Fuente, L F; San Primitivo, F; Arranz, J-J

    2009-08-01

    Improvement of milk production traits in dairy sheep is required to increase the competitiveness of the industry and to maintain the production of high quality cheese in regions of Mediterranean countries with less favourable conditions. Additional improvement over classical selection could be reached if genes with significant effects on the relevant traits were specifically targeted by selection. However, so far, few studies have been undertaken to detect quantitative trait loci (QTL) in dairy sheep. In this study, we present a complete genome scan performed in a commercial population of Spanish Churra sheep to identify chromosomal regions associated with phenotypic variation observed in milk production traits. Eleven half-sib families, including a total of 1213 ewes, were analysed following a daughter design. Genome-wise multi-marker regression analysis revealed a genome-wise significant QTL for milk protein percentage on chromosome 3. Eight other regions, localized on chromosomes 1, 2, 20, 23 and 25, showed suggestive significant linkage associations with some of the analysed traits. To our knowledge, this study represents the first complete genome scan for milk production traits reported in dairy sheep. The experiment described here shows that analysis of commercial dairy sheep populations has the potential to increase our understanding of the genetic determinants of complex production-related traits.

  8. Mapping Quantitative Trait Loci Controlling Endosperm Traits with Molecular Marker

    Institute of Scientific and Technical Information of China (English)

    XU Chen-wu; LI Tao; SUN Chang-sen; GU Shi-liang

    2002-01-01

    Based on the genetic models for triploid endosperm traits and on the methods for mapping diploid quantitative traits loci (QTLs), the genetic constitutions, components of means and genetic variances of QTL controlling endosperm traits under flanking marker genotypes of different generations were presented. From these results, a multiple linear regression method for mapping QTL underlying endosperm traits in cereals was proposed, which used the means of endosperm traits under flanking marker genotypes as a dependent variable, the coefficient of additive effect ( d ) and dominance effect ( h 1 and/or h2 ) of a putative QTL in a given interval as independent variables. This method can work at any position in a genome covered by markers and increase the estimation precision of QTL location and their effects by eliminating the interference of other relative QTLs. This method can also be easily used in other uneven data such as markers and quantitative traits detected or measured in plants and tissues different either in generations or at chromosomal ploidy levels, and in endosperm traits controlled by complicated genetic models considering the effects produced by genotypes of both maternal plants and seeds on them.

  9. 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

  10. And the Winner is – Acquired

    DEFF Research Database (Denmark)

    Henkel, Joachim; Rønde, Thomas; Wagner, Marcus

    value in case of success—that is, a more radical innovation. In the second stage, successful entrants bid to be acquired by the incumbent. We assume that entrants cannot survive on their own, so being acquired amounts to a ‘prize’ in a contest. We identify an equilibrium in which the incumbent chooses...

  11. Freshwater Biological Traits Database (Final Report)

    Science.gov (United States)

    EPA announced the release of the final report, Freshwater Biological Traits Database. This report discusses the development of a database of freshwater biological traits. The database combines several existing traits databases into an online format. The database is also...

  12. 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.

  13. Quantitative Trait Loci for Fertility Traits in Finnish Ayrshire Cattle

    DEFF Research Database (Denmark)

    Schulman, Nina F; Sahana, Goutam; Lund, Mogens S

    2008-01-01

    A whole genome scan was carried out to detect quantitative trait loci (QTL) for fertility traits in Finnish Ayrshire cattle. The mapping population consisted of 12 bulls and 493 sons. Estimated breeding values for days open, fertility treatments, maternal calf mortality and paternal non-return rate...... if these effects were due to a pleiotropic QTL affecting fertility and milk yield traits or to linked QTL causing the effects. This distinction could only be made with confidence on BTA1 where a QTL affecting milk yield is linked to a pleiotropic QTL affecting days open and fertility treatments...

  14. Small-Scale Habitat-Specific Variation and Adaptive Divergence of Photosynthetic Pigments in Different Alkali Soils in Reed Identified by Common Garden and Genetic Tests

    Science.gov (United States)

    Qiu, Tian; Jiang, LiLi; Li, ShanZhi; Yang, YunFei

    2017-01-01

    Flexibility of photosynthetic pigment traits is an important adaptive mechanism through which plants can increase mean fitness in a variable environment. Unlike morphological traits in plants, photosythesis has been shown to exhibit phenotypic plasticity, responding rapidly to environmental conditions. Meanwhile, local adaptation at small scales is considered to be rare. Thus, detecting the small-scale adaptive divergence of photosynthetic pigments presents a challenge. Leaf concentrations of photosynthetic pigments under stressful conditions may be reduced or maintained. Concentrations of some pigments and/or ratio of Chlorophyll a (Chla) to Chlorophyll b (Chlb) do not change markedly in some species, such as the common reed, Phragmites australis, a cosmopolitan grass and common invader. Little is known about photosynthetic responses of this plant to varying levels of alkali salt. Few studies have attempted to account for the relationship between pigment accumulation and leaf position in wild plant populations in grasslands. In this study, photosynthetic pigment concentrations and the total Chl(a+b)/Car ratio decreased as the growing season progressed and were shown to be significantly lower in the habitat with a higher soil pH value and less moisture when compared between habitats. The Chla/Chlb ratio did not differ significantly between habitats, although it increased significantly over time. Leaves in the middle position may be functionally important in the response to soil conditions because only pigment concentrations and the Chl(a+b)/Car ratio of those leaves varied between habitats significantly. The outlier loci, used to evaluate molecular signatures of selection, were detected by Arlequin, Bayescan, and Bayenv analyses. In the simulated habitats of common garden, the local genotypes had higher values of Chla, Chlb, Chl(a+b), Car in their home habitat than did genotypes originating from the other habitat. QST–FST comparisons provided evidence of

  15. Correlated evolution of stem and leaf hydraulic traits in Pereskia (Cactaceae).

    Science.gov (United States)

    Edwards, Erika J

    2006-01-01

    Recent studies have demonstrated significant correlations between stem and leaf hydraulic properties when comparing across species within ecological communities. This implies that these traits are co-evolving, but there have been few studies addressing plant water relations within an explicitly evolutionary framework. This study tests for correlated evolution among a suite of plant water-use traits and environmental parameters in seven species of Pereskia (Cactaceae), using phylogenetically independent contrasts. There were significant evolutionary correlations between leaf-specific xylem hydraulic conductivity, Huber Value, leaf stomatal pore index, leaf venation density and leaf size, but none of these traits appeared to be correlated with environmental water availability; only two water relations traits - mid-day leaf water potentials and photosynthetic water use efficiency - correlated with estimates of moisture regime. In Pereskia, it appears that many stem and leaf hydraulic properties thought to be critical to whole-plant water use have not evolved in response to habitat shifts in water availability. This may be because of the extremely conservative stomatal behavior and particular rooting strategy demonstrated by all Pereskia species investigated. These results highlight the need for a lineage-based approach to understand the relative roles of functional traits in ecological adaptation.

  16. Ecophysiological traits may explain the abundance of climbing plant species across the light gradient in a temperate rainforest.

    Science.gov (United States)

    Gianoli, Ernesto; Saldaña, Alfredo; Jiménez-Castillo, Mylthon

    2012-01-01

    Climbing plants are a key component of rainforests, but mechanistic approaches to their distribution and abundance are scarce. In a southern temperate rainforest, we addressed whether the dominance of climbing plants across light environments is associated with the expression of ecophysiological traits. In mature forest and canopy gaps, we measured leaf size, specific leaf area, photosynthetic rate, and dark respiration in six of the most abundant woody vines. Mean values of traits and their phenotypic change (%) between mature forest and canopy gaps were predictor variables. Leaf size and specific leaf area were not significantly associated with climbing plant dominance. Variation in gas-exchange traits between mature forest and canopy gaps explained, at least partly, the dominance of climbers in this forest. A greater increase in photosynthetic rate and a lower increase in dark respiration rate when canopy openings occur were related to the success of climbing plant species. Dominant climbers showed a strategy of maximizing exploitation of resource availability but minimizing metabolic costs. Results may reflect phenotypic plasticity or genetic differentiation in ecophysiological traits between light environments. It is suggested that the dominant climbers in this temperate rainforest would be able to cope with forest clearings due to human activities.

  17. Ecophysiological traits may explain the abundance of climbing plant species across the light gradient in a temperate rainforest.

    Directory of Open Access Journals (Sweden)

    Ernesto Gianoli

    Full Text Available Climbing plants are a key component of rainforests, but mechanistic approaches to their distribution and abundance are scarce. In a southern temperate rainforest, we addressed whether the dominance of climbing plants across light environments is associated with the expression of ecophysiological traits. In mature forest and canopy gaps, we measured leaf size, specific leaf area, photosynthetic rate, and dark respiration in six of the most abundant woody vines. Mean values of traits and their phenotypic change (% between mature forest and canopy gaps were predictor variables. Leaf size and specific leaf area were not significantly associated with climbing plant dominance. Variation in gas-exchange traits between mature forest and canopy gaps explained, at least partly, the dominance of climbers in this forest. A greater increase in photosynthetic rate and a lower increase in dark respiration rate when canopy openings occur were related to the success of climbing plant species. Dominant climbers showed a strategy of maximizing exploitation of resource availability but minimizing metabolic costs. Results may reflect phenotypic plasticity or genetic differentiation in ecophysiological traits between light environments. It is suggested that the dominant climbers in this temperate rainforest would be able to cope with forest clearings due to human activities.

  18. Detection of circular polarization in light scattered from photosynthetic microbes

    CERN Document Server

    Sparks, William B; Germer, Thomas A; Chen, Feng; DasSarma, Shiladitya; DasSarma, Priya; Robb, Frank T; Manset, Nadine; Kolokolova, Ludmilla; Reid, Neill; Macchetto, F Duccio; Martin, William; 10.1073/pnas.0810215106

    2009-01-01

    The identification of a universal biosignature that could be sensed remotely is critical to the prospects for success in the search for life elsewhere in the universe. A candidate universal biosignature is homochirality, which is likely to be a generic property of all biochemical life. Due to the optical activity of chiral molecules, it has been hypothesized that this unique characteristic may provide a suitable remote sensing probe using circular polarization spectroscopy. Here, we report the detection of circular polarization in light scattered by photosynthetic microbes. We show that the circular polarization appears to arise from circular dichroism of the strong electronic transitions of photosynthetic absorption bands. We conclude that circular polarization spectroscopy could provide a powerful remote sensing technique for generic life searches.

  19. Photosynthetic membrane development studied using picosecond fluorescence kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Karukstis, K.K.; Sauer, K.

    1983-01-01

    Using measurements of the kinetics of chlorophyll a fluorescence emission, the development of the photosynthetic membrane during etioplast-to-chloroplast differentiation was investigated. Tthe chlorophyll fluorescence decay kinetics of pea chloroplasts from plants grown under intermittent (2 min light-118 min dark) and continuous light regimes were monitored with a single-proton timing system with picosecond resolution. The changes in the fluorescence yields and decay kinetics were associated with known structural and organizational developmental phenomena in the chloroplast. This correlation provides a more detailed assignment of the origins of the fluorescence decay components than has been previously obtained by studying only mature chloroplasts. In particular, the analysis of the variable kinetics and multiexponential character of the fluorescence emission during thylakoid development focuses on the organization of photosynthetic units and the degree of communication between reaction centers in the same photosystem. These results further demonstrate that the age of etiolated tissue is critical to plastid development.

  20. 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.

  1. Quantum oscillatory exciton migration in photosynthetic reaction centers.

    Science.gov (United States)

    Abramavicius, Darius; Mukamel, Shaul

    2010-08-14

    The harvesting of solar energy and its conversion to chemical energy is essential for all forms of life. The primary photon absorption, transport, and charge separation events, which trigger a chain of chemical reactions, take place in membrane-bound photosynthetic complexes. Whether quantum effects, stemming from entanglement of chromophores, persist in the energy transport at room temperature, despite the rapid decoherence effects caused by environment fluctuations, is under current active debate. If confirmed, these may explain the high efficiency of light harvesting and open up numerous applications to quantum computing and information processing. We present simulations of the photosynthetic reaction center of photosystem II that clearly establish oscillatory energy transport at room temperature originating from interference of quantum pathways. These signatures of quantum transport may be observed by two dimensional coherent optical spectroscopy.

  2. 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.

  3. Spatial coherence of thermal photons favors photosynthetic life

    CERN Document Server

    Manrique, Pedro; Caycedo-Soler, Felipe; Rodríguez, Ferney; Quiroga, Luis; Johnson, Neil

    2015-01-01

    Harvesting of sunlight underpins Life on Earth as well as driving novel energy device design. Though several experiments suggest that excitation energy transport and charge separation within a photosynthetic membrane may benefit from the quantum nature of their dynamics, the effects of spatial coherences in the incident light have been largely ignored. Here we show that spatial correlations in the incident light likely play an important role in trapping light and adding robustness, as well as providing a driving mechanism for an organism's adaptation toward more ordered structures. Our theory is grounded by empirical inputs, while its output is validated against testable predictions. Our results suggest that spatiotemporal correlations between photons, a fundamental property of the quantum world, should play a key role in our understanding of early Life and in improving the design of artificial photosynthetic systems.

  4. Challenges and Perspectives in Designing Artificial Photosynthetic Systems.

    Science.gov (United States)

    Zhou, Han; Yan, Runyu; Zhang, Di; Fan, Tongxiang

    2016-07-11

    The development of artificial photosynthetic systems for water splitting and CO2 reduction on a large scale for practical applications is the ultimate goal towards worldwide sustainability. This Concept highlights the state-of-the-art research trends of artificial photosynthesis concepts and designs from some new perspectives. Particularly, it is focused on five important aspects for the design of promising artificial photosynthetic systems: 1) catalyst development, 2) architecture design, 3) device buildup 4) mechanism exploration, and 5) theoretical investigations. Some typical progress and challenges, the most significant milestones achieved to date, as well as possible future directions are illustrated and discussed. This Concept article presents a selection of new developments to highlight new trends and possibilities, main barriers, or challenges; with this, we hope to inspire more advances in the field of artificial photosynthesis.

  5. 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.

  6. Anatomical structure of moss leaves and their photosynthetic activity

    Directory of Open Access Journals (Sweden)

    Jan Krupa

    2014-01-01

    Full Text Available The photosynthetic activity of the leaf area unit increases depending on the degree of differentiation of the anatomical structure of the leaves of six chosen moss species. There is a correlation between the leaf area and the degree of differentiation of the anatomical structure resulting in enlargement of the area of contact of the assimilating cells with air. The leaves of Catharinea undulata having a one-layer blade and provided with several lamellae show a higher photosynthesis per 1 cm2 of their surface than the one-layer leaves of Mniurnm or Funaria. Aloina leaves are the smallest in area among those of the moss species discussed, however, their photosynthetic rate is almost 4.5 times higher than in Funaria leaves. By analogy to the structure of leaves and their function in vascular, plants, these changes and correlations may be considered as attempts of primeval adaptation of mosses to terrestrial conditions of living.

  7. Electron transfer pathway analysis in bacterial photosynthetic reaction center

    CERN Document Server

    Kitoh-Nishioka, Hirotaka

    2016-01-01

    A new computational scheme to analyze electron transfer (ET) pathways in large biomolecules is presented with applications to ETs in bacterial photosynthetic reaction center. It consists of a linear combination of fragment molecular orbitals and an electron tunneling current analysis, which enables an efficient first-principles analysis of ET pathways in large biomolecules. The scheme has been applied to the ET from menaquinone to ubiquinone via nonheme iron complex in bacterial photosynthetic reaction center. It has revealed that not only the central Fe$^{2+}$ ion but also particular histidine ligands are involved in the ET pathways in such a way to mitigate perturbations that can be caused by metal ion substitution and depletion, which elucidates the experimentally observed insensitivity of the ET rate to these perturbations.

  8. An allosteric photoredox catalyst inspired by photosynthetic machinery.

    Science.gov (United States)

    Lifschitz, Alejo M; Young, Ryan M; Mendez-Arroyo, Jose; Stern, Charlotte L; McGuirk, C Michael; Wasielewski, Michael R; Mirkin, Chad A

    2015-03-30

    Biological photosynthetic machinery allosterically regulate light harvesting via conformational and electronic changes at the antenna protein complexes as a response to specific chemical inputs. Fundamental limitations in current approaches to regulating inorganic light-harvesting mimics prevent their use in catalysis. Here we show that a light-harvesting antenna/reaction centre mimic can be regulated by utilizing a coordination framework incorporating antenna hemilabile ligands and assembled via a high-yielding, modular approach. As in nature, allosteric regulation is afforded by coupling the conformational changes to the disruptions in the electrochemical landscape of the framework upon recognition of specific coordinating analytes. The hemilabile ligands enable switching using remarkably mild and redox-inactive inputs, allowing one to regulate the photoredox catalytic activity of the photosynthetic mimic reversibly and in situ. Thus, we demonstrate that bioinspired regulatory mechanisms can be applied to inorganic light-harvesting arrays displaying switchable catalytic properties and with potential uses in solar energy conversion and photonic devices.

  9. Detecting extraterrestrial life with the Colossus telescope using photosynthetic biosignatures

    Science.gov (United States)

    Berdyugina, S.; Kuhn, J.; Harrington, D.; Moretto, G.; Langlois, M.; Halliday, D.; Harlingten, C.

    2014-03-01

    We propose to search for life on Earth-like planets in habitable zones using photosynthesis biosignatures. Many life forms on Earth process the solar light and utilize it to support their own activity and to provide a valuable energy source for other life forms. We expect therefore that photosynthesis is very likely to arise on another planet and can produce conspicuous biosignatures. We have recently identified biological polarization effects, e.g., selective light absorption or scattering by photosynthetic molecules which can be used for remote detection of extraterrestrial life. Here we present synthetic spectra and polarization of Earth-like planets with photosynthetic life and evaluate the sensitivity of the Colossus telescope for their remote detection in the solar neighborhood.

  10. 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.

  11. Remote sensing of vegetation canopy photosynthetic and stomatal conductance efficiencies

    Science.gov (United States)

    Myneni, R. B.; Ganapol, B. D.; Asrar, G.

    1992-01-01

    The problem of remote sensing the canopy photosynthetic and stomatal conductance efficiencies is investigated with the aid of one- and three-dimensional radiative transfer methods coupled to a semi-empirical mechanistic model of leaf photosynthesis and stomatal conductance. Desertlike vegetation is modeled as clumps of leaves randomly distributed on a bright dry soil with partial ground cover. Normalized difference vegetation index (NDVI), canopy photosynthetic (Ep), and stomatal efficiencies (Es) are calculated for various geometrical, optical, and illumination conditions. The contribution of various radiative fluxes to estimates of Ep is evaluated and the magnitude of errors in bulk canopy formulation of problem parameters are quantified. The nature and sensitivity of the relationship between Ep and Es to NDVI is investigated, and an algorithm is proposed for use in operational remote sensing.

  12. Counting Viruses and Bacteria in Photosynthetic Microbial Mats

    OpenAIRE

    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 typically used in benthic viral ecology were applied to the complex matrix of microbial mats but were found to inefficiently extract viruses. Here, we present a method for extraction and quantifica...

  13. Leaf chlorophyll content as a proxy for leaf photosynthetic capacity.

    Science.gov (United States)

    Croft, Holly; Chen, Jing M; Luo, Xiangzhong; Bartlett, Paul; Chen, Bin; Staebler, Ralf M

    2017-09-01

    Improving the accuracy of estimates of forest carbon exchange is a central priority for understanding ecosystem response to increased atmospheric CO2 levels and improving carbon cycle modelling. However, the spatially continuous parameterization of photosynthetic capacity (Vcmax) at global scales and appropriate temporal intervals within terrestrial biosphere models (TBMs) remains unresolved. This research investigates the use of biochemical parameters for modelling leaf photosynthetic capacity within a deciduous forest. Particular attention is given to the impacts of seasonality on both leaf biophysical variables and physiological processes, and their interdependent relationships. Four deciduous tree species were sampled across three growing seasons (2013-2015), approximately every 10 days for leaf chlorophyll content (ChlLeaf ) and canopy structure. Leaf nitrogen (NArea ) was also measured during 2014. Leaf photosynthesis was measured during 2014-2015 using a Li-6400 gas-exchange system, with A-Ci curves to model Vcmax. Results showed that seasonality and variations between species resulted in weak relationships between Vcmax normalized to 25°C (Vcmax25) and NArea (R(2)  = 0.62, P models to derive ChlLeaf . TBMs largely treat photosynthetic parameters as either fixed constants or varying according to leaf nitrogen content. This research challenges assumptions that simple NArea -Vcmax25 relationships can reliably be used to constrain photosynthetic capacity in TBMs, even within the same plant functional type. It is suggested that ChlLeaf provides a more accurate, direct proxy for Vcmax25 and is also more easily retrievable from satellite data. These results have important implications for carbon modelling within deciduous ecosystems. © 2017 Her Majesty the Queen in Right of Canada.

  14. Stoichiometry and kinetics of mercury uptake by photosynthetic bacteria.

    Science.gov (United States)

    Kis, Mariann; Sipka, Gábor; Maróti, Péter

    2017-05-01

    Mercury adsorption on the cell surface and intracellular uptake by bacteria represent the key first step in the production and accumulation of highly toxic mercury in living organisms. In this work, the biophysical characteristics of mercury bioaccumulation are studied in intact cells of photosynthetic bacteria by use of analytical (dithizone) assay and physiological photosynthetic markers (pigment content, fluorescence induction, and membrane potential) to determine the amount of mercury ions bound to the cell surface and taken up by the cell. It is shown that the Hg(II) uptake mechanism (1) has two kinetically distinguishable components, (2) includes co-opted influx through heavy metal transporters since the slow component is inhibited by Ca(2+) channel blockers, (3) shows complex pH dependence demonstrating the competition of ligand binding of Hg(II) ions with H(+) ions (low pH) and high tendency of complex formation of Hg(II) with hydroxyl ions (high pH), and (4) is not a passive but an energy-dependent process as evidenced by light activation and inhibition by protonophore. Photosynthetic bacteria can accumulate Hg(II) in amounts much (about 10(5)) greater than their own masses by well-defined strong and weak binding sites with equilibrium binding constants in the range of 1 (μM)(-1) and 1 (mM)(-1), respectively. The strong binding sites are attributed to sulfhydryl groups as the uptake is blocked by use of sulfhydryl modifying agents and their number is much (two orders of magnitude) smaller than the number of weak binding sites. Biofilms developed by some bacteria (e.g., Rvx. gelatinosus) increase the mercury binding capacity further by a factor of about five. Photosynthetic bacteria in the light act as a sponge of Hg(II) and can be potentially used for biomonitoring and bioremediation of mercury-contaminated aqueous cultures.

  15. Changes in Endopeptidase Activity during Photosynthetic Declination in Rice Leaf

    Institute of Scientific and Technical Information of China (English)

    DENGZhi-rui; ZHANGRong-xian

    2004-01-01

    Two japonica rice varieties, Wuyujing 3 and 97-7, were used to study the changes in contents of soluble protein, free amino acids and endopeptidase activity, during photosynthetic declination. The content of soluble protein in flag leaf of cv.Wuyujing 3 was higher than that of cv. 97-7, but decreased rapidly in Wuyujing 3. Free amino acids in flag leaf and the thirteenth leaf of Wuyujing 3 started to increase 10 days before the turning point of photosynthetic declination (TPPD), while it occurred just 1-2 days before TPPD in the flag leaf and the thirteenth leaf of 97-7. During reversible phase of photosynthetic declination,endopeptidase activity remained at a low level and increased slightly only in the later part of this phase. Then it rose up rapidly at irreversible decline phase and reached a vety high level. For Wuyujing 3, the change in endopeptidase activity in the thirteenth leaf was parallel to that in flag leaf. However, for 97-7, the rapid increase of endopeptidase activity in the thirteenth leaf started later than that of flag leaf. The results implied that the rate of protein breakdown and conversion to transportable nitrogen in leaves of 97-7 was slower than that in leaves of Wuyujing 3 during photosynthetic declination and it led to relativeh" lower seed setting rate and fully filling grains rate in 97-7. This may be one of the important reasons why 97-7 could not bring the high yicld potentiality into play and the findings may be taken into consideration while breeding for high potential varieties in future.

  16. Changes in Endopeptidase Activity during Photosynthetic Declination in Rice Leaf

    Institute of Scientific and Technical Information of China (English)

    DENG Zhi-rui; ZHANG Rong-xian

    2004-01-01

    Two japonica rice varieties, Wuyujing 3 and 97-7, were used to study the changes in contents of soluble protein, free amino acids and endopeptidase activity during photosynthetic declination. The content of soluble protein in flag leaf of cv.Wuyujing 3 was higher than that of cv. 97-7, but decreased rapidly in Wuyujing 3. Free amino acids in flag leaf and the thirteenth leaf of Wuyujing 3 started to increase 10 days before the turning point of photosynthetic declination (TPPD), while it occurred just 1-2 days before TPPD in the flag leaf and the thirteenth leaf of 97-7. During reversible phase of photosynthetic declination,endopeptidase activity remained at a low level and increased slightly only in the later part of this phase. Then it rose up rapidly at irreversible decline phase and reached a very high level. For Wuyujing 3, the change in endopeptidase activity in the thirteenth leaf was parallel to that in flag leaf. However, for 97-7, the rapid increase of endopeptidase activity in the thirteenth leaf started later than that of flag leaf. The results implied that the rate of protein breakdown and conversion to transportable nitrogen in leaves of 97-7 was slower than that in leaves of Wuyujing 3 during photosynthetic declination and it led to relatively lower seed setting rate and fully filling grains rate in 97-7. This may be one of the important reasons why 97-7 could not bring the high yield potentiality into play and the findings may be taken into consideration while breeding for high potential varieties in future.

  17. Microbiological Hydrogen Production by Anaerobic Fermentation and Photosynthetic Process

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-01

    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)

  18. Quantitative trait loci analysis of swine meat quality traits

    DEFF Research Database (Denmark)

    Li, H D; Lund, M S; Christensen, O F

    2010-01-01

    were estimated from a posterior distribution of the QTL position. In total, 31 QTL for the 6 meat quality traits were found to be significant at the 5% chromosome-wide level, among which 11 QTL were significant at the 5% genome-wide level and 5 of these were significant at the 0.1% genome-wide level...... will be helpful for fine mapping and identifying genes affecting meat quality traits, and tightly linked markers may be incorporated into marker-assisted selection programs......A QTL study was performed in large half-sib families to characterize the genetic background of variation in pork quality traits as well as to examine the possibilities of including QTL in a marker-assisted selection scheme. The quality traits included ultimate pH in LM and the semimembranosus, drip...

  19. Photosynthetic responses to water deficit in six Mediterranean sclerophyll species: possible factors explaining the declining distribution of Rhamnus ludovici-salvatoris, an endemic Balearic species.

    Science.gov (United States)

    Gulías, J; Flexas, J; Abadía, A; Madrano, H

    2002-07-01

    We sought to explain the declining distribution in the Balearic Islands of the endemic shrub Rhamnus ludovici-salvatoris R. Chodat, by comparing its photosynthetic response to drought with that of several widely distributed, competing Mediterranean species (R. alaternus L., Quercus ilex L., Pistacia lentiscus L., Q. humilis Mill. and P. terebinthus L.). All of the study species, except for the two Rhamnus species, avoided desiccation by rapidly adjusting their stomatal conductance at the onset of drought, and maintaining constant leaf relative water content. The two Rhamnus species showed desiccation-tolerant behavior; i.e., as drought progressed, their predawn leaf relative water content decreased simultaneously with stomatal closure. All four desiccation-avoiding species showed a significant positive correlation between leaf thermal dissipation (estimated by the fluorescence parameter NPQ (non-photochemical quenching)) and the de-epoxidation state of the xanthophyll cycle (DPS). The two Rhamnus species exhibited maximum DPS regardless of treatment, but only R. alaternus increased NPQ in response to drought. Rhamnus ludovici-salvatoris had a high ratio of photorespiration to photosynthesis and a low intrinsic water-use efficiency; traits that are likely to be unfavorable for plant productivity under arid conditions. It also had the lowest DPS and thermal dissipation among the six species. We conclude that the photosynthetic traits of R. ludovici-salvatoris account for its limited ability to compete with other species in the Mediterranean region.

  20. Counting viruses and bacteria in photosynthetic microbial mats.

    Science.gov (United States)

    Carreira, Cátia; Staal, Marc; Middelboe, Mathias; Brussaard, Corina P D

    2015-03-01

    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 typically used in benthic viral ecology were applied to the complex matrix of microbial mats but were found to inefficiently extract viruses. Here, we present a method for extraction and quantification of viruses from photosynthetic microbial mats using epifluorescence microscopy (EFM) and flow cytometry (FCM). A combination of EDTA addition, probe sonication, and enzyme treatment applied to a glutaraldehyde-fixed sample resulted in a substantially higher viral (5- to 33-fold) extraction efficiency and reduced background noise compared to previously published methods. Using this method, it was found that in general, intertidal photosynthetic microbial mats harbor very high viral abundances (2.8 × 10(10) ± 0.3 × 10(10) g(-1)) compared with benthic habitats (10(7) to 10(9) g(-1)). This procedure also showed 4.5- and 4-fold-increased efficacies of extraction of viruses and bacteria, respectively, from intertidal sediments, allowing a single method to be used for the microbial mat and underlying sediment.

  1. γ- Irradiation Effect: Variation of Photosynthetic Activity of Euglena

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Objective To study the effects of gamma-ray irradiation on carbon fixation (Specific production rate: SPR), CO2 utilization efficiency (CUE) and electron transfer rate (ETR) in the photosynthetic flagellate Euglena gracilis strain Z in a dose-response dependent manner. Methods Euglena cells were cultured in an inorganic nutrient medium containing ammonium chloride or proteose peptone. Cells were exposed to gamma-ray at 5 doses (0, 100, 250, 350, 500 Gy for water). Five days after irradiation, three photosynthetic activities were measured. SPR, which is a carbon uptake rate per unit carbon mass, was determined by 13C tracer methodology. CUE was evaluated using a relation of carbon isotope fractionation in Calvin cycle. ETR in photosystem II (PS II) was measured by a chlorophyll fluorescence analysis. Results Even at a dose of 500 Gy, 80 % of ETR of the non-irradiated control (0 Gy) was sustained, while SPR and CUE were about half the level in the non-irradiated control at 500 Gy. Furthermore, the dose response of ETR was considerably different from the others. Conclusion Our findings suggest that not only PS II but also the Calvin cycle in the photosynthetic system is affected by gamma ray irradiation.

  2. PHOTOSYNTHETIC PIGMENTS IN HEVEA CLONES UNDER POWDERY MILDEW ATTACK

    Directory of Open Access Journals (Sweden)

    Gisely Cristina Gonzalez

    2013-08-01

    Full Text Available http://dx.doi.org/10.5902/1980509810561The rubber tree [Hevea brasiliensis (Willd. ex Adr. Of Juss. Muell. Arg.] can be affected by the occurrence of the fungus Oidium heveae, which causes one of the most important diseases of rubber trees, powdery mildew. This work studied meet changes in photosynthetic pigments, an indicator of oxidative stress, in seedlings of three Hevea brasiliensis clones, RRIM 600, GT1 and PR255, under infection in Oidium heveae. The experiment was conducted in an open environment under natural photoperiod conditions and at the beginning of the trial, the rubber plants would be inoculated were sprayed with an aqueous suspension containing O. heveae at a concentration of 16 x 104 conidia mL-1. On the day of inoculation and after 48, 96, 144 and 192 h leaf samples were collected for the determination of photosynthetic pigments. Degradation in photosynthetic pigments in the period of infection was observed in rubber tree clones studied; thus, there is oxidative stress in clones of rubber trees. No promising genetic material for genetic improvement work stress tolerance by Oidium heveae was identified.

  3. 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.

  4. 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.

  5. Photosynthetic recovery of desiccated intertidal seaweeds after rehydration

    Institute of Scientific and Technical Information of China (English)

    JI Yan; GAO Kunshan; TANAKA Jiro

    2005-01-01

    Intertidal seaweeds experience periodical desiccation and rehydration to different extents due to the tidal cycles and their vertical distributions. Their photosynthetic recovery process during the rehydration may show different patterns among the seaweeds from different zonations or depths at intertidal zone. In this study 12 species of seaweeds collected from the upper, middle, lower and sublittoral zones were examined. The relationship of the photosynthetic recovery to vertical distribution was assessed by comparing their patterns of photosynthetic and respiratory performances after rehydration following desiccation. Both the photosynthesis and dark respiration declined during emersion, showing certain degrees of recovery after re-immersion into seawater for most species, but the extents were markedly different from one species to the other. The species from upper intertidal zone after being rehydrated for 1 hour, following 2 hours of desiccation, achieved 100 % recovery of their initial physiological activity, while most of the lower or sublittoral species did not achieve full recovery. It is the ability to withstand desiccation stress (fast recovery during rehydration), but not that to avoid desiccation (water retain ing ability) that determines the distribution of intertidal seaweeds. Such physiological behavior during rehydration after desiccation reflects the adaptive strategy of intertidal seaweeds against desiccation and their capabilityof primary production in the process of rehydration.

  6. 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.

  7. Improved hydrogen photoproduction from photosynthetic bacteria and green algae

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, P.F.; Lien, S.; Seibert, M.

    1979-01-01

    Photosynthetic bacteria evolve hydrogen at much higher rates than do other classes of photosynthetic microorganisms. In addition, they tolerate harsh environments, grow rapidly, and utilize both visible and near infrared light in photosynthesis. They do not split water, but this does not necessarily eliminate their potential use in future applied systems. They are easily manipulated genetically, and thus might be modified to metabolize common biomass waste materials in place of expensive defined organic substrates. Furthermore, the potential for increasing hydrogen photoproduction via genetic techniques is promising. Strains that partially degrade cellulose, have high photoproduction rates, or contain very large amounts of the enzymes associated with hydrogen metabolism have been isolated. Green algae also produce hydrogen but are capable of using water as a substrate. For example, C. reinhardi can evolve hydrogen and oxygen at a molar ratio approaching 2:1. Based upon effect of dichlorophenyl dimethylurea (a specific inhibitor of photosystem II, PSII) on hydrogen photoproduction in the wild type strain and upon results obtained with PSII mutants, one can demonstrate that water is the major source of electrons for hydrogen production. The potential efficiency of in vivo coupling between hydrogenase and the photosynthetic electron transport system is high. Up to 76% of the reductants generated by the electron transport system can be channeled directly to the enzyme for in vivo hydrogen production. Rates exceeding 170 ..mu..moles of H/sub 2/ mg Chl/sup -1/ hr/sup -1/ have been observed.

  8. Photosynthetic bicarbonate utilization in Porphyra haitanensis Bangiales,Rhodophyta

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The activities of carbonic anhydrase (CA) and photosynthesis of Porphyra haitanensis were investigated in order to see its photosynthetic utilization of inorganic carbon source. Both intra- and extra-cellular CA activities existed in the thallus. CA inhibitors, acetazolamide (AZ) and ethoxyzolamide (EZ), remarkably depressed the photosynthetic oxygen evolution in seawater of pH 8.2 and 10.0, and EZ showed stronger inhibition than AZ. The observed net photosynthetic rate in seawater of pH 8.2 was much higher than that of CO2 supply theoretically derived from spontaneous dehydration of HCO3-. P. haitanensis also showed a rather high pH compensation point (9.9). The results demonstrated that P. haitanensis could utilize bicarbonate as the external inorganic carbon source for photosynthesis. The bicarbonate utilization was closely associated with dehydration catalyzed by extracellular CA activity. The inorganic carbon composition in seawater could well saturate the photosynthesis of P. haitanensis. The low Km value and compensation points for inorganic carbon reflected the existence of CO2- concentrating mechanism in this alga.

  9. Photosynthetic Physiological Characteristics of Gazania rigens L. Under Drought Stress

    Science.gov (United States)

    Gao, T. T.; Zheng, S. W.; Zhou, X. H.; Wang, D. X.; Lu, X. P.

    2016-08-01

    To investigate the responses of photosynthetic physiological characteristics of Gazania rigens L. to drought stress, the changes of three cultivars (‘Xingbai’, ‘XH’ and ‘Hongwen’) photosynthetic values under drought stress were determined via LI-6400 portable photosynthesis analyzer (LI-COR, USA), and the relationships between photosynthesis and drought resistance of each cultivar were analyzed. The results showed that, three cultivars net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and light use efficiency (LUE) value indicated the trend of decreasing gradually and there existed significant reduction in Pn and Gs values. There were extremely negative significant correlations between drought stress treatment days and Pn, Gs, Tr, water use efficiency (WUE) and LUE values. A small amount of leaves began to turn soft and yellow after drought stress treatment for 10 days, but they could recover to grow quickly after rehydration. The Pn values of ‘Hongwen’ decreased quickly and changed in a large range, so it had a poor resistance; the Pn values of ‘Xingbai’ decreased slowly and changed in a small range, so it had a strong resistance; while the changes of their hybrids -‘XH’ were between its parents. This research would provide a theoretical basis for gazania resistance cultivar breeding and application in landscape.

  10. Photovoltaic concepts inspired by coherence effects in photosynthetic systems

    KAUST Repository

    Brédas, 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.

  11. 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.

  12. The Evolution of Light Stress Proteins in Photosynthetic Organisms

    Directory of Open Access Journals (Sweden)

    Iwona Adamska

    2006-04-01

    Full Text Available The Elip (early light-inducible protein family in pro- and eukaryotic photosynthetic organisms consists of more than 100 different stress proteins. These proteins accumulate in photosynthetic membranes in response to light stress and have photoprotective functions. At the amino acid level, members of the Elip family are closely related to light-harvesting chlorophyll a/b-binding (Cab antenna proteins of photosystem I and II, present in higher plants and some algae. Based on their predicted secondary structure, members of the Elip family are divided into three groups: (a one-helix Hlips (high light-induced proteins, also called Scps (small Cab-like proteins or Ohps (one-helix proteins; (b two-helix Seps (stress-enhanced proteins; and (c three-helix Elips and related proteins. Despite having different physiological functions it is believed that eukaryotic three-helix Cab proteins evolved from the prokaryotic Hlips through a series of duplications and fusions. In this review we analyse the occurrence of Elip family members in various photosynthetic prokaryotic and eukaryotic organisms and discuss their evolutionary relationship with Cab proteins.

  13. Photosynthetic hydrogen and oxygen production by green algae

    Energy Technology Data Exchange (ETDEWEB)

    Greenbaum, E.; Lee, J.W.

    1997-12-31

    An overview of photosynthetic hydrogen and oxygen production by green algae in the context of its potential as a renewable chemical feed stock and energy carrier is presented. Beginning with its discovery by Gaffron and Rubin in 1942, motivated by curiosity-driven laboratory research, studies were initiated in the early 1970s that focused on photosynthetic hydrogen production from an applied perspective. From a scientific and technical point of view, current research is focused on optimizing net thermodynamic conversion efficiencies represented by the Gibbs Free Energy of molecular hydrogen. The key research questions of maximizing hydrogen and oxygen production by light-activated water splitting in green algae are (1) removing the oxygen sensitivity of algal hydrogenases; (2) linearizing the light saturation curves of photosynthesis throughout the entire range of terrestrial solar irradiance--including the role of bicarbonate and carbon dioxide in optimization of photosynthetic electron transport and (3) the minimum number of light reactions that are required to split water to elemental hydrogen and oxygen. Each of these research topics is being actively addressed by the photobiological hydrogen research community.

  14. Mapping the functional connectome traits of levels of consciousness.

    Science.gov (United States)

    Amico, Enrico; Marinazzo, Daniele; Di Perri, Carol; Heine, Lizette; Annen, Jitka; Martial, Charlotte; Dzemidzic, Mario; Kirsch, Murielle; Bonhomme, Vincent; Laureys, Steven; Goñi, Joaquín

    2017-03-01

    Examining task-free functional connectivity (FC) in the human brain offers insights on how spontaneous integration and segregation of information relate to human cognition, and how this organization may be altered in different conditions, and neurological disorders. This is particularly relevant for patients in disorders of consciousness (DOC) following severe acquired brain damage and coma, one of the most devastating conditions in modern medical care. We present a novel data-driven methodology, connICA, which implements Independent Component Analysis (ICA) for the extraction of robust independent FC patterns (FC-traits) from a set of individual functional connectomes, without imposing any a priori data stratification into groups. We here apply connICA to investigate associations between network traits derived from task-free FC and cognitive/clinical features that define levels of consciousness. Three main independent FC-traits were identified and linked to consciousness-related clinical features. The first one represents the functional configuration of a "resting" human brain, and it is associated to a sedative (sevoflurane), the overall effect of the pathology and the level of arousal. The second FC-trait reflects the disconnection of the visual and sensory-motor connectivity patterns. It also relates to the time since the insult and to the ability of communicating with the external environment. The third FC-trait isolates the connectivity pattern encompassing the fronto-parietal and the default-mode network areas as well as the interaction between left and right hemispheres, which are also associated to the awareness of the self and its surroundings. Each FC-trait represents a distinct functional process with a role in the degradation of conscious states of functional brain networks, shedding further light on the functional sub-circuits that get disrupted in severe brain-damage. Copyright © 2017. Published by Elsevier Inc.

  15. Culinary and sensory traits diversity in the Spanish Core Collection of common beans (Phaseolus vulgaris L.

    Directory of Open Access Journals (Sweden)

    Pedro A. Casquero

    2016-03-01

    Full Text Available The Spanish National Plant Genetic Resource Center’s core collection of bean germplasm includes 202 accessions selected from more than 3000 accessions in function of passport data, seed phenotype, genetic background, and agronomic traits. To acquire more useful information about these accessions, we cultivated and characterized them for sensory and culinary traits. We found considerable variation for culinary and sensory traits of the cooked beans (mean coefficients of variation: 41% for the sensory traits and 40% for the culinary traits. The large dataset enabled us to study correlations between sensory and culinary traits and among these traits and geographic origin, seed color, and growth habit. Greater proportion of white in the seed coat correlated positively with brightness and negatively with mealiness (r=0.60, r=-0.60, p<0.001, respectively. Mealiness correlated negatively with seed-coat roughness and rate of water absorption (r=-0.60, r=-0.53, p<0.001, respectively. Materials of Andean origin had lower seed-coat brightness (p<0.01 and seed-coat roughness, and greater seed-coat perceptibility, mealiness, flavor, and aroma (p<0.001 than materials of Mesoamerican origin. Growth habit failed to correlate with culinary or sensory traits. Breeders can benefit from the information about this core collection available at www.crf.inia.es/crfesp/paginaprincipaljudia.asp.

  16. Culinary and sensory traits diversity in the Spanish Core Collection of common beans (Phaseolus vulgaris L.)

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, A.; Casquero, P.A.; Mayo, S.; Almirall, A.; Plans, M.; Simó, J.; Romero-del-Castillo, R.; Casañas, F.

    2016-11-01

    The Spanish National Plant Genetic Resource Center’s core collection of bean germplasm includes 202 accessions selected from more than 3000 accessions in function of passport data, seed phenotype, genetic background, and agronomic traits. To acquire more useful information about these accessions, we cultivated and characterized them for sensory and culinary traits. We found considerable variation for culinary and sensory traits of the cooked beans (mean coefficients of variation: 41% for the sensory traits and 40% for the culinary traits). The large dataset enabled us to study correlations between sensory and culinary traits and among these traits and geographic origin, seed color, and growth habit. Greater proportion of white in the seed coat correlated positively with brightness and negatively with mealiness (r=0.60, r=-0.60, p<0.001, respectively). Mealiness correlated negatively with seed-coat roughness and rate of water absorption (r=-0.60, r=-0.53, p<0.001, respectively). Materials of Andean origin had lower seed-coat brightness (p<0.01) and seed-coat roughness, and greater seed-coat perceptibility, mealiness, flavor, and aroma (p<0.001) than materials of Mesoamerican origin. Growth habit failed to correlate with culinary or sensory traits. Breeders can benefit from the information about this core collection available at www.crf.inia.es/crfesp/paginaprincipaljudia.asp. (Author)

  17. Manganese accumulation in rice: implications for photosynthetic functioning.

    Science.gov (United States)

    Lidon, Fernando Cebola; Barreiro, Maria Graça; Ramalho, José Cochicho

    2004-11-01

    In order to gain fundamental insights into the nature of the adaptation to Mn excess, the characterisation of the photosynthetic apparatus in Mn-treated rice was carried out in 21-day-old plants. We found 17- and 11-fold increases in Mn in the leaf tissues and in thylakoid, respectively, when the plants were grown hydroponically in nutrient solutions with Mn concentrations between 0.125 and 32 mg l(-1) (2.3 and 582.5 microM). Net photosynthesis and the photosynthetic capacity decreased after the 0.5 and 2 mg l(-1) (9.1 and 36.4 microM) Mn treatment, respectively. The stomatal conductance displayed a similar trend to that of photosynthetic capacity. The levels of basal chlorophyll fluorescence and the ratio between variable and maximum chlorophyll fluorescence did not vary significantly among treatments, but the photochemical quenching and the quantum yield of non-cyclic electron transport increased until the 2 mg l(-1) (36.4 microM) Mn treatment. The lipid matrix of thylakoids revealed a global increase in the proportions of phospholipids, relative to galactolipids. This pattern was coupled with diminishing levels of monogalactosyldiacylglycerol. The relative ratio between total carotenoids and total chlorophylls decreased until the last Mn treatment, yet the levels of carotenes, zeaxanthin, and violaxanthin plus antheraxanthin displayed different patterns. It was further found that the de-epoxidation state involving the components of the xanthophylls cycle increased until the 8 mg l(-1) (145.6 microM) Mn treatment. The levels of the photosynthetic electron carriers displayed different patterns, with plastocyanin and the high and low forms of cytochrome b559 remaining steady, whereas cytochromes b563 and f increased until the 8 mg l(-1) (145.6 microM) Mn treatment and the quinone pool increased until the highest Mn treatment. It was concluded that Mn-mediated inhibition of rice photosynthesis barely implicates stomatal conductance, as well as the distribution of

  18. 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

  19. Forming impressions from incongruent traits.

    Science.gov (United States)

    Casselden, P A; Hampson, S E

    1990-08-01

    The factors that affect the ease with which impressions are formed from incongruent trait pairs are investigated. In Experiments 1 and 2, trait pairs that were both descriptively and evaluatively congruent, as well as ones that were only evaluatively congruent, were found to be more imaginable and to be perceived as more frequently co-occurring than incongruent trait pairs. In Experiment 3, response latency provided a converging measure of ease of imaginability. Experiment 4 examined written descriptions of targets described by these trait pairs, and found more attempts to integrate the congruent than the incongruent pairs. These findings are discussed in terms of the relation between laypersons' impressions of personality and formal personality assessment.

  20. Authoritarian Personality Traits Among Students

    Science.gov (United States)

    Dunham, J.

    1973-01-01

    The results are reported of an investigation into the social attitudes of the total population (800) of one English university using Adorno's F scale to measure authoritarian personality traits. (Author)

  1. Enhancing Medicares Hospital Acquired Conditions Policy

    Data.gov (United States)

    U.S. Department of Health & Human Services — The current Medicare policy of non-payment to hospitals for Hospital Acquired Conditions (HAC) seeks to avoid payment for preventable complications identified within...

  2. Common acquired kidney diseases in children

    African Journals Online (AJOL)

    5. Common acquired kidney diseases in children. Examination of the urine is probably the most ... rheumatic fever and APSGN should not ... remains unknown. ... Volume overload may also cause ..... systematic review of observational studies.

  3. Hospital-Acquired Condition Reduction Program

    Data.gov (United States)

    U.S. Department of Health & Human Services — In October 2014, CMS began reducing Medicare payments for subsection (d) hospitals that rank in the worst performing quartile with respect to hospital-acquired...

  4. The evolution of costly acquired immune memory

    National Research Council Canada - National Science Library

    Best, Alex; Hoyle, Andy

    2013-01-01

    A key feature of the vertebrate adaptive immune system is acquired immune memory, whereby hosts launch a faster and heightened response when challenged by previously encountered pathogens, preventing full infection...

  5. 7 CFR 926.10 - Acquire.

    Science.gov (United States)

    2010-01-01

    ... of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE DATA COLLECTION, REPORTING AND RECORDKEEPING REQUIREMENTS APPLICABLE TO CRANBERRIES NOT SUBJECT TO THE CRANBERRY MARKETING ORDER § 926.10 Acquire....

  6. Enhancing Medicares Hospital Acquired Conditions Policy

    Data.gov (United States)

    U.S. Department of Health & Human Services — The current Medicare policy of non-payment to hospitals for Hospital Acquired Conditions (HAC) seeks to avoid payment for preventable complications identified within...

  7. Acquired uniparental disomy in myeloproliferative neoplasms.

    Science.gov (United States)

    Score, Joannah; Cross, Nicholas C P

    2012-10-01

    The finding of somatically acquired uniparental disomy, where both copies of a chromosome pair or parts of chromosomes have originated from one parent, has led to the discovery of several novel mutated genes in myeloproliferative neoplasms and related disorders. This article examines how the development of single nucleotide polymorphism array technology has facilitated the identification of regions of acquired uniparental disomy and has led to a much greater understanding of the molecular pathology of these heterogeneous diseases.

  8. The evolution of costly acquired immune memory

    OpenAIRE

    Best, A.; Hoyle, A

    2013-01-01

    A key feature of the vertebrate adaptive immune system is acquired immune memory, whereby hosts launch a faster and heightened response when challenged by previously encountered pathogens, preventing full infection. Here, we use a mathematical model to explore the role of ecological and epidemiological processes in shaping selection for costly acquired immune memory. Applying the framework of adaptive dynamics to the classic SIR (Susceptible-Infected-Recovered) epidemiological model, we focus...

  9. Acquiring Evolving Technologies: Web Services Standards

    Science.gov (United States)

    2016-06-30

    2006 Carnegie Mellon University Acquiring Evolving Technologies: Web Services Standards Harry L. Levinson Software Engineering Institute Carnegie...Acquiring Evolving Technologies: Web Services Standards 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...NUMBER OF PAGES 22 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Standard Form

  10. Acquired pure red cell aplasia in children

    Directory of Open Access Journals (Sweden)

    Sujata R Dafale

    2012-01-01

    Full Text Available Acquired Pure Red Cell Aplasia (PRCA is a rare occurrence in children.This is a case of an eight year old girl child who developed acquired PRCA secondary to long term intake of sodium Valproate. This case is reported to review the causes of PRCA in children and to reconsider the use of drugs of longer duration in children and adults.

  11. Acquiring Secure Systems Through Information Economics

    Science.gov (United States)

    2015-05-01

    Acquiring Secure Systems Through Information Economics Chad Dacus Research Professor of Defense Economics Air Force Research Institute Dr. Pano...to 00-00-2015 4. TITLE AND SUBTITLE Acquiring Secure Systems Through Information Economics 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...If adversary can hack into mission essential software/hardware, then mission is compromised • Mission assurance requires materiel solutions, educated

  12. Spectral Bio-indicator Simulations for Tracking Photosynthetic Activities in a Corn Field

    Science.gov (United States)

    Cheng, Yen-Ben; Middleton, Elizabeth M.; Huemmrich, K. Fred; Zhang, Qingyuan; Corp, Lawrence; Campbell, Petya; Kustas, William

    2011-01-01

    Accurate assessment of vegetation canopy optical properties plays a critical role in monitoring natural and managed ecosystems under environmental changes. In this context, radiative transfer (RT) models simulating vegetation canopy reflectance have been demonstrated to be a powerful tool for understanding and estimating spectral bio-indicators. In this study, two narrow band spectroradiometers were utilized to acquire observations over corn canopies for two summers. These in situ spectral data were then used to validate a two-layer Markov chain-based canopy reflectance model for simulating the Photochemical Reflectance Index (PRI), which has been widely used in recent vegetation photosynthetic light use efficiency (LUE) studies. The in situ PRI derived from narrow band hyperspectral reflectance exhibited clear responses to: 1) viewing geometry which affects the asset of light environment; and 2) seasonal variation corresponding to the growth stage. The RT model (ACRM) successfully simulated the responses to the variable viewing geometry. The best simulations were obtained when the model was set to run in the two layer mode using the sunlit leaves as the upper layer and shaded leaves as the lower layer. Simulated PRI values yielded much better correlations to in situ observations when the cornfield was dominated by green foliage during the early growth, vegetative and reproductive stages (r = 0.78 to 0.86) than in the later senescent stage (r = 0.65). Further sensitivity analyses were conducted to show the important influences of leaf area index (LAI) and the sunlit/shaded ratio on PRI observations.

  13. Changes in foliar carbon isotope composition and seasonal stomatal conductance reveal adaptive traits in Mediterranean coppices affected by drought

    Institute of Scientific and Technical Information of China (English)

    Giovanni Di Matteo; Luigi Perini; Paolo Atzori; Paolo De Angelis; Tiziano Mei; Giada Bertini; Gianfranco Fabbio; Giuseppe Scarascia Mugnozza

    2014-01-01

    We estimated water-use efficiency and potential photosyn-thetic assimilation of Holm oak (Quercus ilex L.) on slopes of NW and SW aspects in a replicated field test examining the effects of intensifying drought in two Mediterranean coppice forests. We used standard tech-niques for quantifying gas exchange and carbon isotopes in leaves and analyzed total chlorophyll, carotenoids and nitrogen in leaves collected from Mediterranean forests managed under the coppice system. We pos-tulated that responses to drought of coppiced trees would lead to differ-ential responses in physiological traits and that these traits could be used by foresters to adapt to predicted warming and drying in the Mediterra-nean area. We observed physiological responses of the coppiced trees that suggested acclimation in photosynthetic potential and water-use effi-ciency:(1) a significant reduction in stomatal conductance (p<0.01) was recorded as the drought increased at the SW site;(2) foliarδ13C increased as drought increased at the SW site (p<0.01);(3) variations in levels of carotenoids and foliar nitrogen, and differences in foliar morphology were recorded, and were tentatively attributed to variation in photosyn-thetic assimilation between sites. These findings increase knowledge of the capacity for acclimation of managed forests in the Mediterranean region of Europe.

  14. Combined expression trait correlations and expression quantitative trait locus mapping.

    Directory of Open Access Journals (Sweden)

    Hong Lan

    2006-01-01

    Full Text Available Coordinated regulation of gene expression levels across a series of experimental conditions provides valuable information about the functions of correlated transcripts. The consideration of gene expression correlation over a time or tissue dimension has proved valuable in predicting gene function. Here, we consider correlations over a genetic dimension. In addition to identifying coregulated genes, the genetic dimension also supplies us with information about the genomic locations of putative regulatory loci. We calculated correlations among approximately 45,000 expression traits derived from 60 individuals in an F2 sample segregating for obesity and diabetes. By combining the correlation results with linkage mapping information, we were able to identify regulatory networks, make functional predictions for uncharacterized genes, and characterize novel members of known pathways. We found evidence of coordinate regulation of 174 G protein-coupled receptor protein signaling pathway expression traits. Of the 174 traits, 50 had their major LOD peak within 10 cM of a locus on Chromosome 2, and 81 others had a secondary peak in this region. We also characterized a Riken cDNA clone that showed strong correlation with stearoyl-CoA desaturase 1 expression. Experimental validation confirmed that this clone is involved in the regulation of lipid metabolism. We conclude that trait correlation combined with linkage mapping can reveal regulatory networks that would otherwise be missed if we studied only mRNA traits with statistically significant linkages in this small cross. The combined analysis is more sensitive compared with linkage mapping alone.

  15. 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

  16. Investigating the construct of trauma-related acquired callousness among delinquent youth: differences in emotion processing.

    Science.gov (United States)

    Bennett, Diana C; Kerig, Patricia K

    2014-08-01

    This study tested theories regarding differences in emotion processing among youth characterized by primary versus acquired callous-unemotional (CU) traits in a sample of 417 detained adolescents (306 boys, 111 girls). Mixture modeling identified 2 groups of youth high in CU, but with different levels of posttraumatic stress symptoms consistent with theoretical conceptualizations of acquired CU as being linked to trauma. Differences between the 2 groups of youth were investigated regarding 3 dimensions of emotion processing: emotion regulation, numbing, and recognition. Compared to youth classified in the primary group, youth classified as acquired CU demonstrated greater difficulty with lack of clarity (OR = 0.53), and nonacceptance of emotions, (OR = 0.57), general numbing of emotions (OR = 0.87), and recognition of disgust (OR = 0.18). Differences in emotion processing reported by youth in the 2 groups are consistent with theories regarding acquired callousness as related to emotional detachment in the aftermath of posttraumatic distress. The results of the current study have implications for the classification of primary and acquired CU, as well as the clinical treatment of youth with these characteristics.

  17. 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.

  18. Modulation of host immunity and reproduction by horizontally acquired Wolbachia.

    Science.gov (United States)

    Pigeault, Romain; Braquart-Varnier, Christine; Marcadé, Isabelle; Mappa, Gaëtan; Mottin, Elmina; Sicard, Mathieu

    2014-11-01

    The Wolbachia are symbiotic bacteria vertically transmitted from one host generation to another. However, a growing amount of data shows that horizontal transfers of Wolbachia also frequently occur within and between host species. The consequences of the arrival of new symbionts on host physiology can be studied by their experimental introduction in asymbiotic hosts. After experimental transfers of the eight major isopod Wolbachia strains in the isopod Porcellio dilatatus only two of them (wCon and wDil) were found to (1) have no pathogenic effect on the host and (2) be able to pass vertically to the host offspring. In the present work, we studied the influence of these two strains, able to complete an horizontal transfer, on immunity and reproduction of P. dilatatus at two stages of the transfer: (1) in recipient hosts that encounter the symbionts: to test the influence of symbiont when acquired during host life and (2) in vertically infected offspring: to test the influence of a symbiotic interaction occurring all lifelong. The impact of Wolbachia varied depending on the stage: there were clearer effects in vertically infected individuals than in those that acquired the symbionts during their lives. Moreover, the two Wolbachia strains showed contrasted effects: the strain wCon tended to reduce the reproductive investment but to maintain or increase immune parameters whilst wDil had positive effects on reproductive investment but decreased the investment in some immune parameters. These results suggest that horizontally acquisition of Wolbachia can influence the balance between host immune and reproductive traits.

  19. 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.

  20. Biophysical consequences of photosynthetic temperature acclimation for climate

    Science.gov (United States)

    Smith, Nicholas G.; Lombardozzi, Danica; Tawfik, Ahmed; Bonan, Gordon; Dukes, Jeffrey S.

    2017-03-01

    Photosynthetic temperature acclimation is a commonly observed process that is increasingly being incorporated into Earth System Models (ESMs). While short-term acclimation has been shown to increase carbon storage in the future, it is uncertain whether acclimation will directly influence simulated future climate through biophysical mechanisms. Here, we used coupled atmosphere-biosphere simulations using the Community Earth System Model (CESM) to assess how acclimation-induced changes in photosynthesis influence global climate under present-day and future (RCP 8.5) conditions. We ran four 30 year simulations that differed only in sea surface temperatures and atmospheric CO2 (present or future) and whether a mechanism for photosynthetic temperature acclimation was included (yes or no). Acclimation increased future photosynthesis and, consequently, the proportion of energy returned to the atmosphere as latent heat, resulting in reduced surface air temperatures in areas and seasons where acclimation caused the biggest increase in photosynthesis. However, this was partially offset by temperature increases elsewhere, resulting in a small, but significant, global cooling of 0.05°C in the future, similar to that expected from acclimation-induced increases in future land carbon storage found in previous studies. In the present-day simulations, the photosynthetic response was not as strong and cooling in highly vegetated regions was less than warming elsewhere, leading to a net global increase in temperatures of 0.04°C. Precipitation responses were variable and rates did not change globally in either time period. These results, combined with carbon-cycle effects, suggest that models without acclimation may be overestimating positive feedbacks between climate and the land surface in the future.

  1. Alternating electron and proton transfer steps in photosynthetic water oxidation.

    Science.gov (United States)

    Klauss, André; Haumann, Michael; Dau, Holger

    2012-10-02

    Water oxidation by cyanobacteria, algae, and plants is pivotal in oxygenic photosynthesis, the process that powers life on Earth, and is the paradigm for engineering solar fuel-production systems. Each complete reaction cycle of photosynthetic water oxidation requires the removal of four electrons and four protons from the catalytic site, a manganese-calcium complex and its protein environment in photosystem II. In time-resolved photothermal beam deflection experiments, we monitored apparent volume changes of the photosystem II protein associated with charge creation by light-induced electron transfer (contraction) and charge-compensating proton relocation (expansion). Two previously invisible proton removal steps were detected, thereby filling two gaps in the basic reaction-cycle model of photosynthetic water oxidation. In the S(2) → S(3) transition of the classical S-state cycle, an intermediate is formed by deprotonation clearly before electron transfer to the oxidant (Y Z OX). The rate-determining elementary step (τ, approximately 30 µs at 20 °C) in the long-distance proton relocation toward the protein-water interface is characterized by a high activation energy (E(a) = 0.46 ± 0.05 eV) and strong H/D kinetic isotope effect (approximately 6). The characteristics of a proton transfer step during the S(0) → S(1) transition are similar (τ, approximately 100 µs; E(a) = 0.34 ± 0.08 eV; kinetic isotope effect, approximately 3); however, the proton removal from the Mn complex proceeds after electron transfer to . By discovery of the transient formation of two further intermediate states in the reaction cycle of photosynthetic water oxidation, a temporal sequence of strictly alternating removal of electrons and protons from the catalytic site is established.

  2. Transpiration-induced changes in the photosynthetic capacity of leaves.

    Science.gov (United States)

    Sharkey, T D

    1984-02-01

    High transpiration rates were found to affect the photosynthetic capacity of Xanthium strumarium L. leaves in a manner analagous to that of low soil water potential. The effect was also looked for and found in Gossypium hirsutum L., Agathis robusta (C. Moore ex Muell.) Bailey, Eucalyptus microcarpa Maiden, Larrea divaricata Cav., the wilty flacca tomato mutant (Lycopersicon esculentum (L.) Mill.) and Scrophularia desertorum (Munz) Shaw. Two methods were used to distinguish between effects on stomatal conductance, which can lower assimilation by reducing CO2 availability, and effects on the photosynthetic capacity of the mesophyll. First, the response of assimilation to intercellular CO2 pressure (C i) was compared under conditions of high and low transpiration. Second, in addition to estimating C i using the usual Ohm's law analogy, C i was measured directly using the closed-loop technique of T.D. Sharkey, K. Imai, G.D. Farquhar and I.R. Cowan (1982, Plant Physiol, 60, 657-659). Transpiration stress responses of Xanthium strumarium were compared with soil drought effects. Both stresses reduced photosynthesis at high C i but not at low C i; transpiration stress increased the quantum requirement of photosynthesis. Transpiration stress could be induced in small sections of leaves. Total transpiration from the plant did not influence the photosynthetic capacity of a leaf kept under constant conditions, indicating that water deficits develop over small areas within the leaf. The effect of high transpiration on photosynthesis was reversed approximately half-way by returning the plants to low-transpiration conditions. This reversal occurred as fast as measurements could be made (5 min), but little further recovery was observed in subsequent hours.

  3. THE INFLUENCE OF GRAMOXONE HERBICIDE ON THE CONTENT OF THE PHOTOSYNTHETIC PIGMENTS IN ZEA MAYS

    Directory of Open Access Journals (Sweden)

    Antoanela Patras

    2007-08-01

    Full Text Available The active substance of Gramoxone herbicide is interacting with plant’s photosynthetic systems, playing the role of final acceptor of the photosynthetic electrons. Except this known mode of action, it has been also observed the inhibitory action on the protoporphyrinogen oxidase – essential enzyme for chlorophylls biosynthesis, and also the decrease of photosynthetic pigment’s concentration in some spontaneous plants. Based on these prerequisites, the present study demonstrates the decrease of the photosynthetic pigment’s content in Zea mays in the presence of Gramoxone.

  4. Photosynthetic recovery in Arctic caribou forage lichens following a long-term field sulfur dioxide fumigation

    Energy Technology Data Exchange (ETDEWEB)

    Moser, T.J.; Nash, T.H. III; Olafsen, A.G.

    1983-01-01

    The gross photosynthetic response of Cladonia stellaris, cladonia rangiferina, and Cetraria cucullata was monitored during three growing seasons subsequent to a long-term, in situ SO/sub 2/ fumigation conducted in 1978 at Anaktuvuk Pass, AK. The lichen vegetation which had experienced the greatest SO/sub 2/stress during the 1978 fumigation remained photosynthetically inactive. Significant photosynthetic recovery was discovered in the test species which had experienced sublethal concentrations of SO/sub 2/; however, their photosynthetic capacities remained less than controls.

  5. Expectancies and Self-Efficacy Mediate the Effects of Impulsivity on Marijuana Use Outcomes: An Application of the Acquired Preparedness Model

    OpenAIRE

    Hayaki, Jumi; Herman, Debra S.; Hagerty, Claire E.; de Dios, Marcel A.; Anderson, Bradley J.; Stein, Michael D

    2010-01-01

    This study tests the acquired preparedness model (APM) to explain associations among trait impulsivity, social learning principles, and marijuana use outcomes in a community sample of female marijuana users. The APM states that individuals with high-risk dispositions are more likely to acquire certain types of learning that, in turn, instigate problematic substance use behaviors. In this study, three domains of psychosocial learning were tested: positive and negative marijuana use expectancie...

  6. Comprehensive comparative analysis of kinesins in photosynthetic eukaryotes

    Directory of Open Access Journals (Sweden)

    Reddy Anireddy SN

    2006-01-01

    Full Text Available Abstract Background Kinesins, a superfamily of molecular motors, use microtubules as tracks and transport diverse cellular cargoes. All kinesins contain a highly conserved ~350 amino acid motor domain. Previous analysis of the completed genome sequence of one flowering plant (Arabidopsis has resulted in identification of 61 kinesins. The recent completion of genome sequencing of several photosynthetic and non-photosynthetic eukaryotes that belong to divergent lineages offers a unique opportunity to conduct a comprehensive comparative analysis of kinesins in plant and non-plant systems and infer their evolutionary relationships. Results We used the kinesin motor domain to identify kinesins in the completed genome sequences of 19 species, including 13 newly sequenced genomes. Among the newly analyzed genomes, six represent photosynthetic eukaryotes. A total of 529 kinesins was used to perform comprehensive analysis of kinesins and to construct gene trees using the Bayesian and parsimony approaches. The previously recognized 14 families of kinesins are resolved as distinct lineages in our inferred gene tree. At least three of the 14 kinesin families are not represented in flowering plants. Chlamydomonas, a green alga that is part of the lineage that includes land plants, has at least nine of the 14 known kinesin families. Seven of ten families present in flowering plants are represented in Chlamydomonas, indicating that these families were retained in both the flowering-plant and green algae lineages. Conclusion The increase in the number of kinesins in flowering plants is due to vast expansion of the Kinesin-14 and Kinesin-7 families. The Kinesin-14 family, which typically contains a C-terminal motor, has many plant kinesins that have the motor domain at the N terminus, in the middle, or the C terminus. Several domains in kinesins are present exclusively either in plant or animal lineages. Addition of novel domains to kinesins in lineage

  7. Isolation and Biological Characteristics of Photosynthetic Bacterium Strain PSB-1

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@Photosynthetic bacteria(PSB) with multiple functions of applying photo-energy and complex metabolism, are widely spread in lakes, rivers and seas. According to Bergey's manual of systematic bacteriology, the PSB includes at least 27 genera[1]. In recent years, some new species of PSB have been reported The study of PSB is of high value in theory and practice. Some new biochemical compounds derived from PSB are discovered with the potentiality of insecticide, fungicide, herbicide and bacteriacide[8,9].PSB can also be applied to the control of environment,and industries of energy and feed.[8,9,10

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

    Science.gov (United States)

    Lai, Martin C; Lan, Ethan I

    2015-10-27

    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 diversity of bioproducts synthesized by engineered cyanobacteria, the metabolic pathways used, and the current engineering strategies used for increasing their titers.

  9. Continuous Cultivation of Photosynthetic Bacteria for Fatty Acids Production

    OpenAIRE

    Kim, Dong-Hoon; Lee, Ji-Hye; Hwang, Yuhoon; Kang, Seoktae; Kim, Mi-Sun

    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) 4 d, cell concentration continuously increased from 0.97 g dcw/L to 2.05 g dcw/L as lactate concentration increased from 30 mM to 60 mM. At 70 mM, however, cell concentration fluctuated with incomple...

  10. Anatomical variation in Cactaceae and relatives: Trait lability and evolutionary innovation.

    Science.gov (United States)

    Ogburn, R Matthew; Edwards, Erika J

    2009-02-01

    The cacti have undergone extensive specialization in their evolutionary history, providing an excellent system in which to address large-scale questions of morphological and physiological adaptation. Recent molecular phylogenetic studies suggest that (1) Pereskia, the leafy genus long interpreted as the sister group of all other cacti, is likely paraphyletic, and (2) Cactaceae are nested within a paraphyletic Portulacaceae as a member of the "ACPT" clade (Anacampseroteae, Cactaceae, Portulaca, and Talinum). We collected new data on the vegetative anatomy of the ACPT clade and relatives to evaluate whether patterns in the distributions of traits may provide insight into early events in the evolutionary transition to the cactus life form. Many traits had high levels of homoplasy and were mostly equivocal with regard to infraclade relationships of ACPT, although several characters do lend further support to a paraphyletic Pereskia. These include a thick stem cuticle, prominent stem mucilage cells, and hypodermal calcium oxalate druses, all of which are likely to be important traits for stem water storage and photosynthesis. We hypothesize that high lability of many putative "precursor" traits may have been critical in generating the organismal context necessary for the evolution of an efficient and integrated photosynthetic stem.

  11. Regulation of leaf photosynthetic rate correlating with leaf carbohydrate status and activation state of Rubisco under a variety of photosynthetic source/sink balances.

    Science.gov (United States)

    Kasai, Minobu

    2008-09-01

    There is evidence suggesting that in plants changes in the photosynthetic source/sink balance are an important factor that regulates leaf photosynthetic rate through affects on the leaf carbohydrate status. However, to resolve the regulatory mechanism of leaf photosynthetic rate associated with photosynthetic source/sink balance, information, particularly on mutual relationships of experimental data that are linked with a variety of photosynthetic source/sink balances, seems to be still limited. Thus, a variety of manipulations altering the plant source/sink ratio were carried out with soybean plants, and the mutual relationships of various characteristics such as leaf photosynthetic rate, carbohydrate content and the source/sink ratio were analyzed in manipulated and non-manipulated control plants. The manipulations were removal of one-half or all pods, removal of one-third or two-third leaves, and shading of one-third or one-half leaves with soybean plants grown for 8 weeks under 10 h light (24 degrees C) and 14 h darkness (17 degrees C). It was shown that there were significant negative correlations between source/sink ratio (dry weight ratio of attached leaves to other all organs) and leaf photosynthetic rate; source/sink ratio and activation ratio (percentage of initial activity to total activity) of Rubisco in leaf extract; leaf carbohydrate (sucrose or starch) content and photosynthetic rate; carbohydrate (sucrose or starch) content and activation ratio of Rubisco; amount of protein-bound ribulose-1,5-bisphosphate (RuBP) in leaf extract and leaf photosynthetic rate; and the amount of protein-bound RuBP and activation ratio of Rubisco. In addition, there were significant positive correlations between source/sink ratio and leaf carbohydrate (sucrose or starch) content; source/sink ratio and the amount of protein-bound RuBP; carbohydrate (sucrose or starch) content and amount of protein-bound RuBP and the activation ratio of Rubisco and leaf photosynthetic rate

  12. Rhizosphere hydrophobicity: A positive trait in the competition for water.

    Science.gov (United States)

    Zeppenfeld, Thorsten; Balkenhol, Niko; Kóvacs, Kristóf; Carminati, Andrea

    2017-01-01

    The ability to acquire water from the soil is a major driver in interspecific plant competition and it depends on several root functional traits. One of these traits is the excretion of gel-like compounds (mucilage) that modify physical soil properties. Mucilage secreted by roots becomes hydrophobic upon drying, impedes the rewetting of the soil close to the root, the so called rhizosphere, and reduces water availability to plants. The function of rhizosphere hydrophobicity is not easily understandable when looking at a single plant, but it may constitute a competitive advantage at the ecosystem level. We hypothesize that by making the top soil hydrophobic, deep-rooted plants avoid competititon with shallow-rooted plants. To test this hypothesis we used an individual-based model to simulate water uptake and growth of two virtual plant species, one deep-rooted plant capable of making the soil hydrophobic and a shallow-rooted plant. We ran scenarios with different precipitation regimes ranging from dry to wet (350, 700, and 1400 mm total annual precipitation) and from high to low precipitation frequencies (1, 7, and 14 days). Plant species abundance and biomass were chosen as indicators for competitiveness of plant species. At constant precipitation frequency mucilage hydrophobicity lead to a benefit in biomass and abundance of the tap-rooted population. Under wet conditions this effect diminished and tap-rooted plants were less productive. Without this trait both species coexisted. The effect of root exudation trait remained constant under different precipitation frequencies. This study shows that mucilage secretion is a competitive trait for the acquisition of water. This advantage is achieved by the modification of the soil hydraulic properties and specifically by inducing water repellency in soil regions which are shared with other species.

  13. Trait Self-Compassion Reflects Emotional Flexibility Through an Association with High Vagally Mediated Heart Rate Variability.

    Science.gov (United States)

    Svendsen, Julie Lillebostad; Osnes, Berge; Binder, Per-Einar; Dundas, Ingrid; Visted, Endre; Nordby, Helge; Schanche, Elisabeth; Sørensen, Lin

    Converging evidence shows a positive effect of self-compassion on self-reported well-being and mental health. However, few studies have examined the relation between self-compassion and psychophysiological measures. In the present study, we therefore examined the relation between trait self-compassion and vagally mediated heart rate variability (vmHRV) in 53 students (39 female, mean age = 23.63). Trait self-compassion was assessed using the Self-Compassion Scale, and resting vmHRV was measured during a 5-min ECG baseline period. We hypothesized that higher levels of trait self-compassion would predict higher levels of resting vmHRV. Controlling for potential covariates (including age, gender, and BMI), the results confirmed our hypotheses, showing that higher levels of trait self-compassion predicted higher vmHRV. These results were validated with a 24-h measure of vmHRV, acquired from a subsample of the participants (n = 26, 16 female, mean age = 23.85), confirming the positive correlation between high trait self-compassion and higher vmHRV. The relation between trait self-compassion, vmHRV, self-reported trait anxiety (the trait scale of the State-Trait Anxiety Inventory; STAI) and self-reported rumination (the Rumination subscale of the Rumination-Reflection Questionnaire; RRQ-Rum) was also investigated. Higher levels of trait anxiety and rumination were highly correlated with low levels of trait self-compassion. Trait anxiety, but not rumination, correlated marginally significantly with the level of vmHRV. The findings of the present study indicate that trait self-compassion predicts a better ability to physiologically and psychologically adapt emotional responses. Possible implications and limitations of the study are discussed.

  14. Personal traits, cohabitation, and marriage.

    Science.gov (United States)

    French, Michael T; Popovici, Ioana; Robins, Philip K; Homer, Jenny F

    2014-05-01

    This study examines how personal traits affect the likelihood of entering into a cohabitating or marital relationship using a competing risk survival model with cohabitation and marriage as competing outcomes. The data are from Waves 1, 3, and 4 of the National Longitudinal Study of Adolescent Health, a rich dataset with a large sample of young adults (N=9835). A personal traits index is constructed from interviewer-assessed scores on the respondents' physical attractiveness, personality, and grooming. Having a higher score on the personal traits index is associated with a greater hazard of entering into a marital relationship for men and women, but the score does not have a significant influence on entering into a cohabitating relationship. Numerous sensitivity tests support the core findings.

  15. Prevention of hospital-acquired hyponatraemia

    DEFF Research Database (Denmark)

    Lunøe, Mathilde; Overgaard-Steensen, C

    2015-01-01

    for prevention of hospital-acquired hyponatraemia is an understanding of what determines plasma sodium concentration (P-[Na(+) ]) in the individual patient. P-[Na(+) ] is determined by balances of water and cations according to Edelman. This paper discusses the mechanisms influencing water and cation balances...... like Ringer-acetate/Ringer-lactate can increase the intracranial pressure dramatically. Consequently, 0.9 % NaCl is recommended as first-line fluid for such patients. CONCLUSIONS: The occurrence of hospital-acquired hyponatraemia may be reduced by prescribing fluids, type and amount, with the same...

  16. 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.

  17. Plant traits determine forest flammability

    Science.gov (United States)

    Zylstra, Philip; Bradstock, Ross

    2016-04-01

    Carbon and nutrient cycles in forest ecosystems are influenced by their inherent flammability - a property determined by the traits of the component plant species that form the fuel and influence the micro climate of a fire. In the absence of a model capable of explaining the complexity of such a system however, flammability is frequently represented by simple metrics such as surface fuel load. The implications of modelling fire - flammability feedbacks using surface fuel load were examined and compared to a biophysical, mechanistic model (Forest Flammability Model) that incorporates the influence of structural plant traits (e.g. crown shape and spacing) and leaf traits (e.g. thickness, dimensions and moisture). Fuels burn with values of combustibility modelled from leaf traits, transferring convective heat along vectors defined by flame angle and with plume temperatures that decrease with distance from the flame. Flames are re-calculated in one-second time-steps, with new leaves within the plant, neighbouring plants or higher strata ignited when the modelled time to ignition is reached, and other leaves extinguishing when their modelled flame duration is exceeded. The relative influence of surface fuels, vegetation structure and plant leaf traits were examined by comparing flame heights modelled using three treatments that successively added these components within the FFM. Validation was performed across a diverse range of eucalypt forests burnt under widely varying conditions during a forest fire in the Brindabella Ranges west of Canberra (ACT) in 2003. Flame heights ranged from 10 cm to more than 20 m, with an average of 4 m. When modelled from surface fuels alone, flame heights were on average 1.5m smaller than observed values, and were predicted within the error range 28% of the time. The addition of plant structure produced predicted flame heights that were on average 1.5m larger than observed, but were correct 53% of the time. The over-prediction in this

  18. Effects of carbon dioxide concentration and nutrition on photosynthetic functions of white birch seedlings

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S. [Lakehead Univ., Thunder Bay, ON (Canada). Faculty of Forestry and the Forest Environment; Dang, Q.L. [Lakehead Univ., Thunder Bay, ON (Canada). Faculty of Forest and the Forest Environment; Chinese Academy of Sciences, Beijing (China). Inst. of Botany, Laboratory of Quantitative Vegetation Ecology

    2006-11-15

    Increases in atmospheric carbon dioxide (CO{sub 2}) can impact photosynthesis and dry mass production of plants. This study investigated the physiological responses of white birch seedlings to elevated carbon dioxide (CO{sub 2}) at low and high supplies of nitrogen (N), phosphorus (P) and potassium (K). A 2-way factorial experiment was carried out with birch seedlings grown for 4 months in environment-controlled greenhouses. Elevated CO{sub 2} enhanced maximal carboxylation rate and photosynthetically active radiation-saturated electron transport rates were measured after 2.5 and 3.5 months of treatment, as well as actual photochemical efficiency and photosynthetic linear electron transport to carboxylation. Net photosynthetic rate increases were observed as well as increases in photosynthetic water use efficiency (WUE); photosynthetic N efficiency and P efficiency. Stomatal conductance, transpiration rate and the fraction of total photosynthetic linear electron transport partitioned to oxygenation were reduced. Low nutrient availability decreased net photosynthetic rates, WUE, and triose phosphate utilization. However, photosynthetic linear electron transport and N use efficiency increased. There were significant interactive effects of CO{sub 2} and nutrition over time, with evidence of photosynthetic up-regulation in response to elevated CO{sub 2} in seedlings receiving high nutrition. Photosynthetic depression in response to low nutrient availability was attributed to biochemical limitation rather than stomatal limitation. Elevated CO{sub 2} reduced leaf N concentration in seedlings receiving low nutrition, but had no significant effect on leaf P or K concentrations. High nutrient availability generally increased area-based leaf N, P and K concentrations but had negligible effects on K after 2.5 months of treatment. Results suggested that increases in electron partitioning to photorespiration in response to low nutrient availability may be related to

  19. Function and distribution of bilin biosynthesis enzymes in photosynthetic organisms.

    Science.gov (United States)

    Dammeyer, Thorben; Frankenberg-Dinkel, Nicole

    2008-10-01

    Bilins are open-chain tetrapyrrole molecules essential for light-harvesting and/or sensing in many photosynthetic organisms. While they serve as chromophores in phytochrome-mediated light-sensing in plants, they additionally function in light-harvesting in cyanobacteria, red algae and cryptomonads. Associated to phycobiliproteins a variety of bile pigments is responsible for the specific light-absorbance properties of the organisms enabling efficient photosynthesis under different light conditions. The initial step of bilin biosynthesis is the cleavage of heme by heme oxygenases (HO) to afford the first linear molecule biliverdin. This reaction is ubiquitously found also in non-photosynthetic organisms. Biliverdin is then further reduced by site specific reductases most of them belonging to the interesting family of ferredoxin-dependent bilin reductases (FDBRs)-a new family of radical oxidoreductases. In recent years much progress has been made in the field of heme oxygenases but even more in the widespread family of FDBRs, revealing novel biochemical FDBR activities, new crystal structures and new ecological aspects, including the discovery of bilin biosynthesis genes in wild marine phage populations. The aim of this review is to summarize and discuss the recent progress in this field and to highlight the new and remaining questions.

  20. Evanescent cultivation of photosynthetic bacteria on thin waveguides

    Science.gov (United States)

    Pierobon, S. C.; Ooms, M. D.; Sinton, D.

    2014-04-01

    Waveguides with thicknesses similar to biofilms (10-100 µm) provide an opportunity to improve the bioenergy density of biofilm photobioreactors, avoiding the fundamental light- and mass-transport productivity limitations of planktonic photobioreactors. This report investigates the biofilm growth of a mutant of Synechococcus elongatus (PCC 7942) in evanescent light fields that can be scaled over large planar areas. In this study, areas of 7.2 cm2 are illuminated via frustrated total internal reflections on planar waveguides. The resulting photosynthetic biofilm growth showed resilience to surface intensities exceeding photosynthetic limits and a more uniform cell density distribution (1.0 ± 0.3 × 109 mL-1) than predicted from surface light distribution profiles. These results indicate potential for larger area biofilms using the uniform lighting conditions identified. The combination of evanescent illumination with biofilms indicates a modular reactor cell density on the order of 108 mL-1, representing a two orders of magnitude improvement over current facility architectures, with significant potential for further improvement through denser biofilms.

  1. Photosynthetic characteristics of olive tree (Olea europaea) bark.

    Science.gov (United States)

    Filippou, Manolis; Fasseas, Costas; Karabourniotis, George

    2007-07-01

    Functional and structural characteristics of corticular photosynthesis of sun-exposed bark of olive tree (Olea europaea L.) were examined. Stomata are only sporadically present during stem primary growth. Light transmission through the phellem was age dependent, decreasing rapidly in stems older than five years of age. Light transmission was also low in pubescent 1-year-old stems. Light transmission was about 50% higher in wet phellem than in dry phellem. Photosynthetic capacity on a unit area basis (measured with an oxygen disc electrode at 27 degrees C and about 5% CO(2) on chlorophyllous tissue discs isolated from the stem) was higher in 1-, 20- and 30-year-old stems compared with 2-10-year-old stems. Low chlorophyll a/b ratio and light compensation points were recorded in olive stems with low phellem light transmission, in accordance with the shade acclimation hypothesis. The intrinsic photochemical efficiency of photosystem II of all stems, especially young stems, was less than that of the leaves. Our results show that olive tree bark possesses an efficient photosynthetic mechanism that may significantly contribute not only to the reduction in concentrations of CO(2) in the inner bark, but also to whole-tree carbon balance.

  2. 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.

  3. Enzymes involved in organellar DNA replication in photosynthetic eukaryotes

    Directory of Open Access Journals (Sweden)

    Takashi eMoriyama

    2014-09-01

    Full Text Available 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.

  4. 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.

  5. Chlorophyll Fluorescence Imaging Uncovers Photosynthetic Fingerprint of Citrus Huanglongbing.

    Science.gov (United States)

    Cen, Haiyan; Weng, Haiyong; Yao, Jieni; He, Mubin; Lv, Jingwen; Hua, Shijia; Li, Hongye; He, Yong

    2017-01-01

    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. Architecture of the native photosynthetic apparatus of Phaeospirillum molischianum.

    Science.gov (United States)

    Gonçalves, Rui Pedro; Bernadac, Alain; Sturgis, James N; Scheuring, Simon

    2005-12-01

    The ubiquity and importance of photosynthetic organisms in nature has made the molecular mechanisms of photosynthesis a widely studied subject at both structural and functional levels. A current challenge is to understand the supramolecular assembly of the proteins involved in photosynthesis in native membranes. We have used atomic force microscopy to study the architecture of the photosynthetic apparatus and analyze the structure of single molecules in chromatophores of Phaeospirillum molischianum. Core complexes are formed by the reaction center enclosed by an elliptical light harvesting complex 1. LH2 are octameric rings, assembled either with cores or in hexagonally packed LH2 antenna domains. The symmetry mismatch caused by octameric LH2 packing in a hexagonal lattice, that could be avoided in a square lattice, suggests lipophobic effects rather than specific inter-molecular interactions drive protein organization. The core and LH2 complexes are organized to form a supramolecular assembly reminiscent to that found in Rhodospirillum photometricum, and very different from that observed in Rhodobacter sphaeroides, Rb. blasticus, and Blastochloris viridis.

  7. Photosynthetic leaf area modulates tiller bud outgrowth in sorghum.

    Science.gov (United States)

    Kebrom, Tesfamichael H; Mullet, John E

    2015-08-01

    Shoot branches or tillers develop from axillary buds. The dormancy versus outgrowth fates of buds depends on genetic, environmental and hormonal signals. Defoliation inhibits bud outgrowth indicating the role of leaf-derived metabolic factors such as sucrose in bud outgrowth. In this study, the sensitivity of bud outgrowth to selective defoliation was investigated. At 6 d after planting (6 DAP), the first two leaves of sorghum were fully expanded and the third was partially emerged. Therefore, the leaves were selectively defoliated at 6 DAP and the length of the bud in the first leaf axil was measured at 8 DAP. Bud outgrowth was inhibited by defoliation of only 2 cm from the tip of the second leaf blade. The expression of dormancy and sucrose-starvation marker genes was up-regulated and cell cycle and sucrose-inducible genes was down-regulated during the first 24 h post-defoliation of the second leaf. At 48 h, the expression of these genes was similar to controls as the defoliated plant recovers. Our results demonstrate that small changes in photosynthetic leaf area affect the propensity of tiller buds for outgrowth. Therefore, variation in leaf area and photosynthetic activity should be included when integrating sucrose into models of shoot branching.

  8. Photosynthetic Hydrogen and Oxygen Production by Green Algae

    Energy Technology Data Exchange (ETDEWEB)

    Greenbaum, E.; Lee, J.W.

    1999-08-22

    Photosynthesis research at Oak Ridge National Laboratory is focused on hydrogen and oxygen production by green algae in the context of its potential as a renewable fuel and chemical feed stock. Beginning with its discovery by Gaffron and Rubin in 1942, motivated by curiosity-driven laboratory research, studies were initiated in the early 1970s that focused on photosynthetic hydrogen production from an applied perspective. From a scientific and technical point of view, current research is focused on optimizing net thermodynamic conversion efficiencies represented by the Gibbs Free Energy of molecular hydrogen. The key research questions of maximizing hydrogen and oxygen production by light-activated water splitting in green algae are: (1) removing the oxygen sensitivity of algal hydrogenases; (2) linearizing the light saturation curves of hotosynthesis throughout the entire range of terrestrial solar irradiance-including the role of bicarbonate and carbon dioxide in optimization of photosynthetic electron transpor;t and (3) constructing real-world bioreactors, including the generation of hydrogen and oxygen against workable back pressures of the photoproduced gases.

  9. Artificial photosynthetic reaction centers coupled to light-harvesting antennas.

    Science.gov (United States)

    Ghosh, Pulak Kumar; Smirnov, Anatoly Yu; Nori, Franco

    2011-12-01

    We analyze a theoretical model for energy and electron transfer in an artificial photosynthetic system. The photosystem consists of a molecular triad (i.e., with a donor, a photosensitive unit, and an acceptor) coupled to four accessory light-harvesting-antenna pigments. The resonant energy transfer from the antennas to the artificial reaction center (the molecular triad) is described here by the Förster mechanism. We consider two different kinds of arrangements of the accessory light-harvesting pigments around the reaction center. The first arrangement allows direct excitation transfer to the reaction center from all the surrounding pigments. The second configuration transmits energy via a cascade mechanism along a chain of light-harvesting chromophores, where only one chromophore is connected to the reaction center. We show that the artificial photosynthetic system using the cascade energy transfer absorbs photons in a broader wavelength range and converts their energy into electricity with a higher efficiency than the system based on direct couplings between all the antenna chromophores and the reaction center.

  10. 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.

  11. Towards quantification of vibronic coupling in photosynthetic antenna complexes

    Science.gov (United States)

    Singh, V. P.; Westberg, M.; Wang, C.; Dahlberg, P. D.; Gellen, T.; Gardiner, A. T.; Cogdell, R. J.

    2015-01-01

    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. PMID:26049466

  12. Photosynthetic diversity meets biodiversity: the C4 plant example.

    Science.gov (United States)

    Sage, Rowan F; Stata, Matt

    2015-01-01

    Physiological diversification reflects adaptation for specific environmental challenges. As the major physiological process that provides plants with carbon and energy, photosynthesis is under strong evolutionary selection that gives rise to variability in nearly all parts of the photosynthetic apparatus. Here, we discuss how plants, notably those using C4 photosynthesis, diversified in response to environmental challenges imposed by declining atmospheric CO2 content in recent geological time. This reduction in atmospheric CO2 increases the rate of photorespiration and reduces photosynthetic efficiency. While plants have evolved numerous mechanisms to compensate for low CO2, the most effective are the carbon concentration mechanisms of C4, C2, and CAM photosynthesis; and the pumping of dissolved inorganic carbon, mainly by algae. C4 photosynthesis enables plants to dominate warm, dry and often salinized habitats, and to colonize areas that are too stressful for most plant groups. Because C4 lineages generally lack arborescence, they cannot form forests. Hence, where they predominate, C4 plants create a different landscape than would occur if C3 plants were to predominate. These landscapes (mostly grasslands and savannahs) present unique selection environments that promoted the diversification of animal guilds able to graze upon the C4 vegetation. Thus, the rise of C4 photosynthesis has made a significant contribution to the origin of numerous biomes in the modern biosphere.

  13. Toward a photosynthetic microbial platform for terpenoid engineering.

    Science.gov (United States)

    Davies, Fiona K; Jinkerson, Robert E; Posewitz, Matthew C

    2015-03-01

    Plant terpenoids are among the most diverse group of naturally-occurring organic compounds known, and several are used in contemporary consumer products. Terpene synthase enzymes catalyze complex rearrangements of carbon skeleton precursors to yield thousands of unique chemical structures that range in size from the simplest five carbon isoprene unit to the long polymers of rubber. Such chemical diversity has established plant terpenoids as valuable commodity chemicals with applications in the pharmaceutical, neutraceutical, cosmetic, and food industries. More recently, terpenoids have received attention as a renewable alternative to petroleum-derived fuels and as the building blocks of synthetic biopolymers. However, the current plant- and petrochemical-based supplies of commodity terpenoids have major limitations. Photosynthetic microorganisms provide an opportunity to generate terpenoids in a renewable manner, employing a single consolidated host organism that is able to use solar energy, H2O and CO2 as the primary inputs for terpenoid biosynthesis. Advances in synthetic biology have seen important breakthroughs in microbial terpenoid engineering, traditionally via fermentative pathways in yeast and Escherichia coli. This review draws on the knowledge obtained from heterotrophic microbial engineering to propose strategies for the development of microbial photosynthetic platforms for industrial terpenoid production. The importance of utilizing the wealth of genetic information provided by nature to unravel the regulatory mechanisms of terpenoid biosynthesis is highlighted.

  14. Synergistic Two-Photon Absorption Enhancement in Photosynthetic Light Harvesting

    Science.gov (United States)

    Chen, Kuo-Mei; Chen, Yu-Wei; Gao, Ting-Fong

    2012-06-01

    The grand scale fixation of solar energies into chemical substances by photosynthetic reactions of light-harvesting organisms provides Earth's other life forms a thriving environment. Scientific explorations in the past decades have unraveled the fundamental photophysical and photochemical processes in photosynthesis. Higher plants, green algae, and light-harvesting bacteria utilize organized pigment-protein complexes to harvest solar power efficiently and the resultant electronic excitations are funneled into a reaction center, where the first charge separation process takes place. Here we show experimental evidences that green algae (Chlorella vulgaris) in vivo display a synergistic two-photon absorption enhancement in their photosynthetic light harvesting. Their absorption coefficients at various wavelengths display dramatic dependence on the photon flux. This newly found phenomenon is attributed to a coherence-electronic-energy-transfer-mediated (CEETRAM) photon absorption process of light-harvesting pigment-protein complexes of green algae. Under the ambient light level, algae and higher plants can utilize this quantum mechanical mechanism to create two entangled electronic excitations adjacently in their light-harvesting networks. Concerted multiple electron transfer reactions in the reaction centers and oxygen evolving complexes can be implemented efficiently by the coherent motion of two entangled excitons from antennae to the charge separation reaction sites. To fabricate nanostructured, synthetic light-harvesting apparatus, the paramount role of the CEETRAM photon absorption mechanism should be seriously considered in the strategic guidelines.

  15. The genetic basis of anoxygenic photosynthetic arsenite oxidation

    Science.gov (United States)

    Hernandez-Maldonado, Jamie; Sanchez-Sedillo, Benjamin; Stoneburner, Brendon; Boren, Alison; Miller, Laurence G.; McCann, Shelley; Rosen, Michael R.; Oremland, Ronald S.; Saltikov, Chad W.

    2017-01-01

    “Photoarsenotrophy”, the use of arsenite as an electron donor for anoxygenic photosynthesis, is thought to be an ancient form of phototrophy along with the photosynthetic oxidation of Fe(II), H2S, H2, and NO2-. Photoarsenotrophy was recently identified from Paoha Island's (Mono Lake, CA) arsenic-rich hot springs. The genomes of several photoarsenotrophs revealed a gene cluster, arxB2AB1CD, where arxA is predicted to encode for the sole arsenite oxidase. The role of arxA in photosynthetic arsenite oxidation was confirmed by disrupting the gene in a representative photoarsenotrophic bacterium, resulting in the loss of light-dependent arsenite oxidation. In situ evidence of active photoarsenotrophic microbes was supported by arxA mRNA detection for the first time, in red-pigmented microbial mats within the hot springs of Paoha Island. This work expands on the genetics for photosynthesis coupled to new electron donors and elaborates on known mechanisms for arsenic metabolism, thereby highlighting the complexities of arsenic biogeochemical cycling.

  16. Linking canopy reflectance to crop structure and photosynthesis to capture and interpret spatiotemporal dimensions of per-field photosynthetic productivity

    Science.gov (United States)

    Xue, Wei; Jeong, Seungtaek; Ko, Jonghan; Tenhunen, John

    2017-03-01

    Nitrogen and water availability alter canopy structure and physiology, and thus crop growth, yielding large impacts on ecosystem-regulating/production provisions. However, to date, explicitly quantifying such impacts remains challenging partially due to lack of adequate methodology to capture spatial dimensions of ecosystem changes associated with nitrogen and water effects. A data fitting, where close-range remote-sensing measurements of vegetation indices derived from a handheld instrument and an unmanned aerial vehicle (UAV) system are linked to in situ leaf and canopy photosynthetic traits, was applied to capture and interpret inter- and intra-field variations in gross primary productivity (GPP) in lowland rice grown under flooded conditions (paddy rice, PD) subject to three nitrogen application rates and under rainfed conditions (RF) in an East Asian monsoon region of South Korea. Spatial variations (SVs) in both GPP and light use efficiency (LUEcabs) early in the growing season were enlarged by nitrogen addition. The nutritional effects narrowed over time. A shift in planting culture from flooded to rainfed conditions strengthened SVs in GPP and LUEcabs. Intervention of prolonged drought late in the growing season dramatically intensified SVs that were supposed to seasonally decrease. Nevertheless, nitrogen addition effects on SV of LUEcabs at the early growth stage made PD fields exert greater SVs than RF fields. SVs of GPP across PD and RF rice fields were likely related to leaf area index (LAI) development less than to LUEcabs, while numerical analysis suggested that considering strength in LUEcabs and its spatial variation for the same crop type tends to be vital for better evaluation in landscape/regional patterns of ecosystem photosynthetic productivity at critical phenology stages.

  17. [Effects of different tillage methods on photosynthetic characteristics, dry matter production and economic benefit of double cropping soybean].

    Science.gov (United States)

    Tang, Jiang-hua; Su, Li-li; Li, Ya-jie; Xu, Wen-xiu; Peng, Jiang-long

    2016-01-01

    In order to explore suitable mode of high yield cultivation of double cropping soybean after wheat under drip irrigation in northern Xinjiang, field trials were set in 2013-2014 to investigate physiological indices and agronomic traits of double cropping soybean under different tillage methods under drip irrigation. The results showed that leaf area index (LAI), chlorophyll content (SPAD), leaf net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (g(s)) during the determination period under different tillage methods were in the order of tillage plus film covering (TP)> tillage (T)> rotary tillage (RT) > no-tillage (NT) , and the concentration of intercellular CO₂(Ci) was the opposite. LAI, SPAD, Pn, Tr, and g(s) of TP were higher than that with NT by 55.0%, 9.1%, 41.8%, 37.5% and 56.4%, respectively, and Ci was decreased by 22.1%. TP enhanced the photosynthetic efficiency of soybean and improved the ability of CO₂assimilation, consequently leading to the increase of soybean yield under TP compared to NT. The plant dry matter accumulation of TP treatment was improved greatly, with the pod number and seeds number per plant, 100-seed mass and yield of quadric sowing soybean being increased by 50.3%, 48.1%, 11.8% and 20.8% compared with that under NT, and the differences were significant. Therefore, the plastic film mulching combined with tillage under drip irrigation technology was suitable for double cropping soybean after wheat in northern Xinjiang under this experimental condition.

  18. Relative importance of photosynthetic physiology and biomass allocation for tree seedling growth across a broad light gradient.

    Science.gov (United States)

    Montgomery, Rebecca

    2004-02-01

    Studies of tree seedling physiology and growth under field conditions provide information on the mechanisms underlying inter- and intraspecific differences in growth and survival at a critical period during forest regeneration. I compared photosynthetic physiology, growth and biomass allocation in seedlings of three shade-tolerant tree species, Virola koschynii Warb., Dipteryx panamensis (Pittier) Record & Mell and Brosimum alicastrum Swartz., growing across a light gradient created by a forest-pasture edge (0.5 to 67% diffuse transmittance (%T)). Most growth and physiological traits showed nonlinear responses to light availability, with the greatest changes occurring between 0.5 and 20 %T. Specific leaf area (SLA) and nitrogen per unit leaf mass (N mass) decreased, maximum assimilation per unit leaf area (A area) and area-based leaf N concentration (N area) increased, and maximum assimilation per unit leaf mass (A mass) did not change with increasing irradiance. Plastic responses in SLA were important determinants of leaf N and A area across the gradient. Species differed in magnitude and plasticity of growth; B. alicastrum had the lowest relative growth rates (RGR) and low plasticity. Its final biomass varied only 10-fold across the light gradient. In contrast, the final biomass of D. panamensis and V. koschynii varied by 100- and 50-fold, respectively, and both had higher RGR than B. alicastrum. As light availability increased, all species decreased biomass allocation to leaf tissue (mass and area) and showed a trade-off between allocation to leaf area at a given plant mass (LAR) and net gain in mass per unit leaf area (net assimilation rate, NAR). This trade-off largely reflected declines in SLA with increasing light. Finally, A area was correlated with NAR and both were major determinants of intraspecific variation in RGR. These data indicate the importance of plasticity in photosynthetic physiology and allocation for variation in tree seedling growth among

  19. 17 CFR 210.3-05 - Financial statements of businesses acquired or to be acquired.

    Science.gov (United States)

    2010-04-01

    ... General Instructions As to Financial Statements § 210.3-05 Financial statements of businesses acquired or... financial statements of related businesses may be presented on a combined basis for any periods they are... registered to be offered to the security holders of the business to be acquired, the financial...

  20. Acquired alexia with agraphia syndrome in childhood.

    Science.gov (United States)

    Paquier, Philippe F; De Smet, Hyo Jung; Mariën, Peter; Poznanski, Nathalie; Van Bogaert, Patrick

    2006-04-01

    The acquired alexia with agraphia syndrome is a conspicuous disorder of reading and writing in the absence of significant other language impairments that has mainly been recorded in adults. Pure cases are rare, with most patients displaying mild aphasic deficits. In children, acquired reading and writing disorders are generally reported as part of more encompassing aphasic syndromes affecting oral and written language equally, for example, Broca or Wernicke aphasia. Documented instances of predominant acquired reading and writing disorders in childhood are exceptional. We report an 11-year-old, right-handed boy who sustained a left temporoparieto-occipital hematoma following rupture of an arteriovenous malformation and who consecutively presented with the acquired alexia with agraphia syndrome associated with word-finding difficulties. Neuropsychologic and neurolinguistic data showed that there was no concomitant Gerstmann and/or angular gyrus syndrome. Th e recoveryfrom the anomia was quite favorable, but recovery of written language was more protracted and acted on the patient's further scholastic achievement. This case is reminiscent of a historical childhood case reported in 1939 and is consonant with adult cases in terms of lesion location and semiologic picture.

  1. Community-Acquired Pneumonia in Indonesia

    NARCIS (Netherlands)

    H. Farida (Helmia)

    2015-01-01

    markdownabstract__Abstract__ __Background:__ Knowledge about the etiology and management of community-acquired pneumonia (CAP) in Indonesia is lacking. __Methods:__ Hospital-based and a population-based cohort studies were carried out during 2007-2011 in Semarang, Indonesia. __Results:__

  2. Sexually acquired Salmonella Typhi urinary tract infection.

    Science.gov (United States)

    Wielding, Sally; Scott, Gordon

    2016-05-01

    We report a case of isolated urinary Salmonella enterica serotype Typhi in an HIV-positive man who has sex with men. He was clinically well and blood and stool cultures were negative, indicating that this may have been a sexually acquired urinary tract infection.

  3. Acquired double pylorus:A case report

    Institute of Scientific and Technical Information of China (English)

    Qing-Yu Chen; Yan Chen; Liang; Jing Wang; Qin Du; Jian-Ting Cai; Jia-Min Chen

    2012-01-01

    Double pylorus is one of the rare anomalies of the gastrointestinal tract, it can be congenital or acquired. In this case we report a case of double pylorus because of chronic peptic ulcer. Upper GI endoscopy revealed gastroduodenal fistula located on the lesser curve of the antrum, the patient's symptoms were improved rapidly by intensive antiulcer treatment.

  4. Acquired antibiotic resistance genes:an overview

    NARCIS (Netherlands)

    Hoek, A.H. van; Mevius, D.; Guerra, B.; Mullany, P.; Robberts, A.P.

    2011-01-01

    In this review an overview is given on antibiotic resistance (AR) mechanisms with special attentions to the AR genes described so far preceded by a short introduction on the discovery and mode of action of the different classes of antibiotics. As this review is only dealing with acquired resistance,

  5. Acquired antibiotic resistance genes: an overview

    NARCIS (Netherlands)

    Hoek, van A.H.; Mevius, D.J.; Guerra, B.; Mullany, P.; Roberts, A.P.; Aarts, H.J.

    2011-01-01

    In this review an overview is given on antibiotic resistance (AR) mechanisms with special attentions to the AR genes described so far preceded by a short introduction on the discovery and mode of action of the different classes of antibiotics. As this review is only dealing with acquired resistance,

  6. Mitral valve repair in acquired dextrocardia.

    Science.gov (United States)

    Elmistekawy, Elsayed; Chan, Vincent; Hynes, Mark; Mesana, Thierry

    2015-10-01

    Surgical correction of valvular heart disease in patients with dextrocardia is extremely rare. We report a surgical case of mitral valve repair in a patient with acquired dextrocardia. Successful mitral valve repair was performed through a right lateral thoracotomy. We describe our surgical strategy and summarize the literature.

  7. Acute acquired comitant esotropia of childhood

    DEFF Research Database (Denmark)

    Hesgaard, Helena; Vinding, Troels

    2015-01-01

    PURPOSE: To identify characteristics of pediatric patients who develop acute acquired comitant esotropia (AACE) with and without intracranial disease. METHODS: We reviewed the charts of 48 children consecutively referred to the hospital with AACE during a 13-year period. Inclusion criteria were...

  8. Monitoring Agitated Behavior After acquired Brain Injury

    DEFF Research Database (Denmark)

    Aadal, Lena; Mortensen, Jesper; Nielsen, Jørgen Feldbaek

    2016-01-01

    Purpose: To describe the onset, duration, intensity, and nursing shift variation of agitated behavior in patients with acquired brain injury (ABI) at a rehabilitation hospital. Design: Prospective descriptive study. Methods: A total of 11 patients with agitated behavior were included. Agitated...

  9. Immunomodulation in community-acquired pneumonia

    NARCIS (Netherlands)

    Remmelts, H.H.F.

    2013-01-01

    Community-acquired pneumonia (CAP) is a common disease with considerable morbidity and mortality, despite effective antibiotic treatment. In this thesis, we showed that the major causative microorganisms in CAP trigger distinct inflammatory response profiles in the host. While an inflammatory respon

  10. Acquired Demyelinating Syndromes and Pediatric Multiple Sclerosis

    NARCIS (Netherlands)

    I.A. Ketelslegers (Immy)

    2014-01-01

    markdownabstract__Abstract__ Acquired inflammatory demyelinating diseases of the central nervous system (CNS) cause damage to myelin sheaths and typically result in white matter lesions due to inflammation, myelin loss and axonal pathology. Clinically, this may result in transient, relapsing or pro

  11. Does chromatin remodeling mark systemic acquired resistance?

    NARCIS (Netherlands)

    Burg, van den H.A.; Takken, F.L.W.

    2009-01-01

    The recognition of plant pathogens activates local defense responses and triggers a long-lasting systemic acquired resistance (SAR) response. Activation of SAR requires the hormone salicylic acid (SA), which induces SA-responsive gene expression. Recent data link changes in gene expression to chroma

  12. Acquired antibiotic resistance genes:an overview

    NARCIS (Netherlands)

    Hoek, A.H. van; Mevius, D.; Guerra, B.; Mullany, P.; Robberts, A.P.

    In this review an overview is given on antibiotic resistance (AR) mechanisms with special attentions to the AR genes described so far preceded by a short introduction on the discovery and mode of action of the different classes of antibiotics. As this review is only dealing with acquired resistance,

  13. Acquired antibiotic resistance genes: an overview

    NARCIS (Netherlands)

    Hoek, van A.H.; Mevius, D.J.; Guerra, B.; Mullany, P.; Roberts, A.P.; Aarts, H.J.

    2011-01-01

    In this review an overview is given on antibiotic resistance (AR) mechanisms with special attentions to the AR genes described so far preceded by a short introduction on the discovery and mode of action of the different classes of antibiotics. As this review is only dealing with acquired resistance,

  14. Acquired nasal deformities in fighter pilots.

    Science.gov (United States)

    Schreinemakers, Joyce R C; van Amerongen, Pieter; Kon, Moshe

    2010-07-01

    Fighter pilots may develop slowly progressive deformities of their noses during their flying careers. The spectrum of deformities that may be acquired ranges from soft tissue to osseous changes. The main cause is the varying pressure exerted by the oxygen mask on the skin and bony pyramid of the nose during flying.

  15. Chronic Acquired Demyelinating Polyneuropathy following Renal Transplantation

    OpenAIRE

    Younger, D. S.; Stuart Orsher

    2013-01-01

    The clinical, laboratory, and treatment findings of a patient with chronic acquired demyelinating polyneuropathy (CADP) in association with renal transplantation are described. Like the present case, many such patients have been described under the rubric of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).

  16. Severe acquired anaemia in Africa: new concepts

    NARCIS (Netherlands)

    M. Boele van Hensbroek; F. Jonker; I. Bates

    2011-01-01

    Severe anaemia is common in Africa. It has a high mortality and particularly affects young children and pregnant women. Recent research provides new insights into the mechanisms and causes of severe acquired anaemia and overturns accepted dogma. Deficiencies of vitamin B12 and vitamin A, but not of

  17. ACQUIRED CUTIS LAXA WITH RECURRENT URTICARIA

    Directory of Open Access Journals (Sweden)

    Ganaparthi

    2015-05-01

    Full Text Available A 30 year old male patient presented with progressive laxity and wrinkling of skin over the face for past 10 years, patient also gives history of recurrent urticaria since 12 years. Skin biopsy using Verhoff Van Gieson stain suggestive of cutis laxa. We are reporting a rare case of acquired cutis laxa with recurrent urticaria

  18. Photoperiodic Regulation of the Seasonal Pattern of Photosynthetic Capacity and the Implications for Carbon Cycling

    Energy Technology Data Exchange (ETDEWEB)

    Bauerle, William L. [Colorado State University, Fort Collins; Oren, Ram [Duke University; Way, Danielle A. [Duke University; Qian, Song S. [Duke University; Stoy, Paul C. [Montana State University; Thornton, Peter E [ORNL; Bowden, Joseph D. [Colorado State University, Fort Collins; Hoffman, Forrest M [ORNL; Reynolds, Robert F. [Clemson University

    2012-01-01

    Although temperature is an important driver of seasonal changes in photosynthetic physiology, photoperiod also regulates leaf activity. Climate change will extend growing seasons if temperature cues predominate, but photoperiod-controlled species will show limited responsiveness to warming. We show that photoperiod explains more seasonal variation in photosynthetic activity across 23 tree species than temperature. Although leaves remain green, photosynthetic capacity peaks just after summer solstice and declines with decreasing photoperiod, before air temperatures peak. In support of these findings, saplings grown at constant temperature but exposed to an extended photoperiod maintained high photosynthetic capacity, but photosynthetic activity declined in saplings experiencing a naturally shortening photoperiod; leaves remained equally green in both treatments. Incorporating a photoperiodic correction of photosynthetic physiology into a global-scale terrestrial carbon-cycle model significantly improves predictions of seasonal atmospheric CO{sub 2} cycling, demonstrating the benefit of such a function in coupled climate system models. Accounting for photoperiod-induced seasonality in photosynthetic parameters reduces modeled global gross primary production 2.5% ({approx}4 PgC y{sup -1}), resulting in a >3% ({approx}2 PgC y{sup -1}) decrease of net primary production. Such a correction is also needed in models estimating current carbon uptake based on remotely sensed greenness. Photoperiod-associated declines in photosynthetic capacity could limit autumn carbon gain in forests, even if warming delays leaf senescence.

  19. Photoperiodic regulation of the seasonal pattern of photosynthetic capacity and the implications for carbon cycling.

    Science.gov (United States)

    Bauerle, William L; Oren, Ram; Way, Danielle A; Qian, Song S; Stoy, Paul C; Thornton, Peter E; Bowden, Joseph D; Hoffman, Forrest M; Reynolds, Robert F

    2012-05-29

    Although temperature is an important driver of seasonal changes in photosynthetic physiology, photoperiod also regulates leaf activity. Climate change will extend growing seasons if temperature cues predominate, but photoperiod-controlled species will show limited responsiveness to warming. We show that photoperiod explains more seasonal variation in photosynthetic activity across 23 tree species than temperature. Although leaves remain green, photosynthetic capacity peaks just after summer solstice and declines with decreasing photoperiod, before air temperatures peak. In support of these findings, saplings grown at constant temperature but exposed to an extended photoperiod maintained high photosynthetic capacity, but photosynthetic activity declined in saplings experiencing a naturally shortening photoperiod; leaves remained equally green in both treatments. Incorporating a photoperiodic correction of photosynthetic physiology into a global-scale terrestrial carbon-cycle model significantly improves predictions of seasonal atmospheric CO(2) cycling, demonstrating the benefit of such a function in coupled climate system models. Accounting for photoperiod-induced seasonality in photosynthetic parameters reduces modeled global gross primary production 2.5% (∼4 PgC y(-1)), resulting in a >3% (∼2 PgC y(-1)) decrease of net primary production. Such a correction is also needed in models estimating current carbon uptake based on remotely sensed greenness. Photoperiod-associated declines in photosynthetic capacity could limit autumn carbon gain in forests, even if warming delays leaf senescence.

  20. Kinetic characterization of the photosynthetic reaction centres in microalgae by means of fluorescence methodology

    NARCIS (Netherlands)

    Gargano, Immacolata; Olivieri, Giuseppe; Spasiano, Danilo; Andreozzi, Roberto; Pollio, Antonino; Marotta, Raffaele; Ambrosio, D' Nicola; Marzocchella, Antonio

    2015-01-01

    The kinetic characterization of the photosynthetic activity in autotrophic microalgae plays a key role in the design of optimized photobioreactors. This paper presents a procedure to assess kinetic parameters of a three-state photosynthetic reaction centres model. Four kinetic parameters of the

  1. Atomic force microscopy of bacterial photosynthetic systems: a new model for native membrane organization

    NARCIS (Netherlands)

    Bahatyrova, Svetlana

    2005-01-01

    The main goal of this thesis was to investigate the supramolecular architecture of a photosynthetic membrane from Rhodobacter sphaeroides purple bacteria cells. This is extremely timely, since we now know all of the structures of photosynthetic pigment-protein LH and RC complexes, ATP-synthase and b

  2. 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 mecha

  3. Chlorophylls d and f and Their Role in Primary Photosynthetic Processes of Cyanobacteria.

    Science.gov (United States)

    Allakhverdiev, S I; Kreslavski, V D; Zharmukhamedov, S K; Voloshin, R A; Korol'kova, D V; Tomo, T; Shen, J-R

    2016-03-01

    The finding of unique Chl d- and Chl f-containing cyanobacteria in the last decade was a discovery in the area of biology of oxygenic photosynthetic organisms. Chl b, Chl c, and Chl f are considered to be accessory pigments found in antennae systems of photosynthetic organisms. They absorb energy and transfer it to the photosynthetic reaction center (RC), but do not participate in electron transport by the photosynthetic electron transport chain. However, Chl d as well as Chl a can operate not only in the light-harvesting complex, but also in the photosynthetic RC. The long-wavelength (Qy) Chl d and Chl f absorption band is shifted to longer wavelength (to 750 nm) compared to Chl a, which suggests the possibility for oxygenic photosynthesis in this spectral range. Such expansion of the photosynthetically active light range is important for the survival of cyanobacteria when the intensity of light not exceeding 700 nm is attenuated due to absorption by Chl a and other pigments. At the same time, energy storage efficiency in photosystem 2 for cyanobacteria containing Chl d and Chl f is not lower than that of cyanobacteria containing Chl a. Despite great interest in these unique chlorophylls, many questions related to functioning of such pigments in primary photosynthetic processes are still not elucidated. This review describes the latest advances in the field of Chl d and Chl f research and their role in primary photosynthetic processes of cyanobacteria.

  4. 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 mecha

  5. 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

  6. Personality traits and personality disorders.

    Science.gov (United States)

    Deary, I J; Peter, A; Austin, E; Gibson, G

    1998-11-01

    The structure of personality disorder traits was examined in a sample of 400 undergraduates who completed the personality disorder questionnaire from the Structured Clinical Interview for DSM-III-R (SCID-II). The relations between personality disorder and normal personality traits indexed by the Eysenck Personality Questionnaire-Revised (EPQ-R) were examined. The three-cluster model of personality traits--as described in the DSM scheme--found equivocal support. Exploratory principal components analysis and confirmatory factor analysis found four broad factors of personality disorder that overlapped with normal personality traits: an asthenic factor related to neuroticism; an antisocial factor associated with psychoticism; an asocial factor linked to introversion-extraversion; and an anankastic (obsessive-compulsive) factor. There is growing agreement about the number and type of broad personality disorder dimensions; similar dimensions may be found in clinical and non-clinical samples, suggesting that those people with personality disorders differ quantitatively rather than qualitatively from others; and there is substantial overlap between normal and abnormal personality dimensions.

  7. Quantitative Trait Loci and Antagonistic Associations for Two Developmentally Related Traits in the Drosophila Head

    Science.gov (United States)

    Gomez, Federico H.

    2017-01-01

    In insects, some developmentally related traits are negatively correlated. Here, we mapped Quantitative Trait Loci (QTL) for traits of eye size and head capsule, in an intercontinental set of recombinant inbred lines (RILs) of Drosophila melanogaster. Composite interval mapping identified QTL on all major chromosomes. Two negatively correlated traits (size of eyes and between-eyes distance) were influenced by one QTL that appeared to be antagonistic between the traits (QTL cytological range is 25F5–30A6), consistent with a negative genetic correlation between these traits of the head capsule. Comparisons of QTL across traits indicated a nonrandom distribution over the genome, with a considerable overlap between some QTL across traits. Developmentally-related traits were influenced by QTL in a pattern that is consistent both with 1) the sign of the genetic correlation between the traits and 2) a constraint in the micro-evolutionary differentiation in the traits. PMID:28130460

  8. Variation in photosynthetic performance and hydraulic architecture across European beech (Fagus sylvatica L.) populations supports the case for local adaptation to water stress.

    Science.gov (United States)

    Aranda, Ismael; Cano, Francisco Javier; Gascó, Antonio; Cochard, Hervé; Nardini, Andrea; Mancha, Jose Antonio; López, Rosana; Sánchez-Gómez, David

    2015-01-01

    The aim of this study was to provide new insights into how intraspecific variability in the response of key functional traits to drought dictates the interplay between gas-exchange parameters and the hydraulic architecture of European beech (Fagus sylvatica L.). Considering the relationships between hydraulic and leaf functional traits, we tested whether local adaptation to water stress occurs in this species. To address these objectives, we conducted a glasshouse experiment in which 2-year-old saplings from six beech populations were subjected to different watering treatments. These populations encompassed central and marginal areas of the range, with variation in macro- and microclimatic water availability. The results highlight subtle but significant differences among populations in their functional response to drought. Interpopulation differences in hydraulic traits suggest that vulnerability to cavitation is higher in populations with higher sensitivity to drought. However, there was no clear relationship between variables related to hydraulic efficiency, such as xylem-specific hydraulic conductivity or stomatal conductance, and those that reflect resistance to xylem cavitation (i.e., Ψ(12), the water potential corresponding to a 12% loss of stem hydraulic conductivity). The results suggest that while a trade-off between photosynthetic capacity at the leaf level and hydraulic function of xylem could be established across populations, it functions independently of the compromise between safety and efficiency of the hydraulic system with regard to water use at the interpopulation level.

  9. Dependence of Photosynthetic Capacity, Photosynthetic Pigment Allocation, and Carbon Storage on Nitrogen Levels in Foliage of Aspen Stands

    Science.gov (United States)

    Middleton, Elizabeth M.; Sullivan, Joseph H.; Papagno, Andrea J.

    2000-01-01

    The role of foliar nitrogen (N) in the seasonal dynamics and vertical canopy distribution of photosynthetic pigments, photosynthetic capacity, and carbon (C) storage was investigated in boreal broadleaved species. The study was conducted at two different aged stands (60 y and 15 y) in 1994 and 1996 in Saskatchewan, Canada as part of the Boreal Ecosystem-Atmosphere Study (BOREAS). Foliage in upper and lower strata was examined for aspen (Populus tremuloides Michx.) and its associated hazelnut shrub (Corylus americana Walt.). We determined that C accumulation, expressed as dry mass per unit leaf area (mg C cm (exp -2)), was linearly dependent on N content (approximately 0.3- 3.5 mg N cm (exp -2))(r (exp 2) = 0.93, n=383, P less than 0.001) when eleven foliage groups were defined according to species, site, and developmental stage. C assembly was greatest in the upper aspen strata of both sites (seasonal average, 40.1 plus or minus 0.6 mg C cm (exp -2)), intermediate in the lower aspen strata (32.7 plus or minus 0.6), and considerably lower, and similar, in the hazelnut shrub layers (23.7 plus or minus 0.6) and in expanding aspen leaves (23.8 plus or minus 0.5); the lowest C assembly per unit N occurred in the two youngest, emerging leaf groups (17.1 plus or minus 0.6). Other relationships among physiological and biochemical variables were typically non-linear and were confounded by inclusion of the three groups of young (i.e., emerging or expanding) leaves, unless these were separately identified. Net C uptake, measured as photosynthetic capacity (A (sub max), micromole CO2 m (exp -2) s (exp -1)), was greater in aspen throughout the season, and optimal in mid-summer at a C:N ratio of approximately 18 (approximately 2.3 %N). When young leaves were excluded and logarithms of both variables were used, A (sub max) was approximately linearly dependent on N (mg N cm (exp-2) (r (exp 2) = 0.85, n= 193, P less than 0.001), attributed to incorporation of N into photosynthetic

  10. 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

    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...... production in relation to photon flux density differed considerably between entire communities and individual thallus parts. No light saturation occurred in the communities, and all photosynthetic variables such as light compensation point, efficiency of light utilisation at low light and maximum production...

  11. Comparison of Net Photosynthetic Rate in Leaves of Soybean with Different Yield Levels

    Institute of Scientific and Technical Information of China (English)

    Li Da-yong; Zhang Zhi-an; Zheng Dian-jun; Jiang Li-yan; Wang Yuan-li

    2012-01-01

    A total of nine soybean (Glycine max (L.) Merr.) cultivars were divided into three yield levels which were planted under the same environmental condition. The net photosynthetic rate was measured by LI-6400 portable photosynthesis system. The chlorophyll content and specific leaf weight were measured with regular methods. The results showed that the specific leaf weight, chlorophyll content and net photosynthetic rate of high yield varieties were higher than those of low yield varieties. The yield had a significantly positive correlation with the net photosynthetic rate. With the improvement of modem technology, the net photosynthetic rate could be measured quickly and exactly. Hence, net photosynthetic rate could be used as an effective index in the selection of high yield soybean.

  12. 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

  13. Tracking acquired antibiotic resistance in commensal bacteria of Galapagos land iguanas: no man, no resistance.

    Directory of Open Access Journals (Sweden)

    Maria Cristina Thaller

    Full Text Available BACKGROUND: Antibiotic resistance, evolving and spreading among bacterial pathogens, poses a serious threat to human health. Antibiotic use for clinical, veterinary and agricultural practices provides the major selective pressure for emergence and persistence of acquired resistance determinants. However, resistance has also been found in the absence of antibiotic exposure, such as in bacteria from wildlife, raising a question about the mechanisms of emergence and persistence of resistant strains under similar conditions, and the implications for resistance control strategies. Since previous studies yielded some contrasting results, possibly due to differences in the ecological landscapes of the studied wildlife, we further investigated this issue in wildlife from a remote setting of the Galapagos archipelago. METHODOLOGY/PRINCIPAL FINDINGS: Screening for acquired antibiotic resistance was carried out in commensal enterobacteria from Conolophus pallidus, the terrestrial iguana of Isla Santa Fe, where: i the abiotic conditions ensure to microbes good survival possibilities in the environment; ii the animal density and their habits favour microbial circulation between individuals; and iii there is no history of antibiotic exposure and the impact of humans and introduced animal species is minimal except for restricted areas. Results revealed that acquired antibiotic resistance traits were exceedingly rare among bacteria, occurring only as non-dominant strains from an area of minor human impact. CONCLUSIONS/SIGNIFICANCE: Where both the exposure to antibiotics and the anthropic pressure are minimal, acquired antibiotic resistance traits are not normally found in bacteria from wildlife, even if the ecological landscape is highly favourable to bacterial circulation among animals. Monitoring antibiotic resistance in wildlife from remote areas could also be a useful tool to evaluate the impact of anthropic pressure.

  14. Stress strengthens memory of first impressions of others' positive personality traits.

    Directory of Open Access Journals (Sweden)

    Johanna Lass-Hennemann

    Full Text Available Encounters with strangers bear potential for social conflict and stress, but also allow the formation of alliances. First impressions of other people play a critical role in the formation of alliances, since they provide a learned base to infer the other's future social attitude. Stress can facilitate emotional memories but it is unknown whether stress strengthens our memory for newly acquired impressions of other people's personality traits. To answer this question, we subjected 60 students (37 females, 23 males to an impression-formation task, viewing portraits together with brief positive vs. negative behavior descriptions, followed by a 3-min cold pressor stress test or a non-stressful control procedure. The next day, novel and old portraits were paired with single trait adjectives, the old portraits with a trait adjective matching the previous day's behavior description. After a filler task, portraits were presented again and subjects were asked to recall the trait adjective. Cued recall was higher for old (previously implied than the novel portraits' trait adjectives, indicating validity of the applied test procedures. Overall, recall rate of implied trait adjectives did not differ between the stress and the control group. However, while the control group showed a better memory performance for others' implied negative personality traits, the stress group showed enhanced recall for others' implied positive personality traits. This result indicates that post-learning stress affects consolidation of first impressions in a valence-specific manner. We propose that the stress-induced strengthening of memory of others' positive traits forms an important cue for the formation of alliances in stressful conditions.

  15. Stress Strengthens Memory of First Impressions of Others' Positive Personality Traits

    Science.gov (United States)

    Lass-Hennemann, Johanna; Kuehl, Linn K.; Schulz, André; Oitzl, Melly S.; Schachinger, Hartmut

    2011-01-01

    Encounters with strangers bear potential for social conflict and stress, but also allow the formation of alliances. First impressions of other people play a critical role in the formation of alliances, since they provide a learned base to infer the other's future social attitude. Stress can facilitate emotional memories but it is unknown whether stress strengthens our memory for newly acquired impressions of other people's personality traits. To answer this question, we subjected 60 students (37 females, 23 males) to an impression-formation task, viewing portraits together with brief positive vs. negative behavior descriptions, followed by a 3-min cold pressor stress test or a non-stressful control procedure. The next day, novel and old portraits were paired with single trait adjectives, the old portraits with a trait adjective matching the previous day's behavior description. After a filler task, portraits were presented again and subjects were asked to recall the trait adjective. Cued recall was higher for old (previously implied) than the novel portraits' trait adjectives, indicating validity of the applied test procedures. Overall, recall rate of implied trait adjectives did not differ between the stress and the control group. However, while the control group showed a better memory performance for others' implied negative personality traits, the stress group showed enhanced recall for others' implied positive personality traits. This result indicates that post-learning stress affects consolidation of first impressions in a valence-specific manner. We propose that the stress-induced strengthening of memory of others' positive traits forms an important cue for the formation of alliances in stressful conditions. PMID:21298099

  16. Traits of Heracleum sosnowskyi Plants in Monostand on Invaded Area.

    Directory of Open Access Journals (Sweden)

    Igor V Dalke

    Full Text Available The ability of giant hogweeds to form monodominant communities and even pure monostands in invaded areas has been well documented. Understanding of the mechanisms leading to monostand formation can aid in determining the limitations of existing community ecology models and establishing an effective management plan for invasive species elimination. The aim of this observational study was to investigate traits of Heracleum sosnowskyi plants (demography, canopy structure, morphology and physiology of the plants in a pure stand in an invaded area useful for understanding potential monostand formation mechanisms. All measurements were performed in one typical Heracleum sosnowskyi monostand located in an abandoned agriculture field located in Syktyvkar city suburb (North-east Russia. This monostand consisted of five main plant growth stages: seed, seedling, juvenile, vegetative adult, and generative adult. Plants of all stages began to grow simultaneously shortly after the snowmelt, at the same time as spring ephemeral plant species grew. The density of generative plants did not change during the vegetation period, but the density of the other plant stages rapidly decreased after the formation of a tall (up to 2-2.5 m and dense (Leaf area index up to 6.5 canopy. The canopy captured approximately 97% of the light. H. sosnowskyi showed high (several orders of magnitude higher than average taiga zone grasses photosynthetic water use efficiency (6-7 μM CO2/μM H2O. Formation of H. sosnowskyi monostands occurs primarily in disturbed areas with relatively rich and well-moistened soils. Early commencement of growth, rapid formation of a dense canopy, high efficiency of light and water use during photosynthesis, ability of young plants to survive in low light conditions, rapid recovery of above-ground plant parts after damage, and the high density of the soil seed bank are the most important traits of H. sosnowskyi plants for monostand formation in invaded

  17. Stability of personality traits in adulthood

    OpenAIRE

    Allemand, Mathias; Gruenenfelder-Steiger, Andrea E; Hill, Patrick L.

    2013-01-01

    Stability represents a fundamental concept in developmental theory and research. In this article we give an overview of recent work on personality traits and their stability in adulthood. First, we define personality traits and stability. Second, we present empirical evidence supporting change and stability of personality traits across the adult years with respect to conceptually and statistically different forms of stability. Third, we describe mechanisms and processes that enable trait stab...

  18. Genetic Variation, Heritability, and Diversity Analysis of Upland Rice (Oryza sativa L. Genotypes Based on Quantitative Traits

    Directory of Open Access Journals (Sweden)

    Mst. Tuhina-Khatun

    2015-01-01

    Full Text Available Upland rice is important for sustainable crop production to meet future food demands. The expansion in area of irrigated rice faces limitations due to water scarcity resulting from climate change. Therefore, this research aimed to identify potential genotypes and suitable traits of upland rice germplasm for breeding programmes. Forty-three genotypes were evaluated in a randomised complete block design with three replications. All genotypes exhibited a wide and significant variation for 22 traits. The highest phenotypic and genotypic coefficient of variation was recorded for the number of filled grains/panicle and yields/plant (g. The highest heritability was found for photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO2, and number of filled grains/panicle and yields/plant (g. Cluster analysis based on 22 traits grouped the 43 rice genotypes into five clusters. Cluster II was the largest and consisted of 20 genotypes mostly originating from the Philippines. The first four principle components of 22 traits accounted for about 72% of the total variation and indicated a wide variation among the genotypes. The selected best trait of the number of filled grains/panicle and yields/plant (g, which showed high heritability and high genetic advance, could be used as a selection criterion for hybridisation programmes in the future.

  19. Genetic Variation, Heritability, and Diversity Analysis of Upland Rice (Oryza sativa L.) Genotypes Based on Quantitative Traits.

    Science.gov (United States)

    Tuhina-Khatun, Mst; Hanafi, Mohamed M; Rafii Yusop, Mohd; Wong, M Y; Salleh, Faezah M; Ferdous, Jannatul

    2015-01-01

    Upland rice is important for sustainable crop production to meet future food demands. The expansion in area of irrigated rice faces limitations due to water scarcity resulting from climate change. Therefore, this research aimed to identify potential genotypes and suitable traits of upland rice germplasm for breeding programmes. Forty-three genotypes were evaluated in a randomised complete block design with three replications. All genotypes exhibited a wide and significant variation for 22 traits. The highest phenotypic and genotypic coefficient of variation was recorded for the number of filled grains/panicle and yields/plant (g). The highest heritability was found for photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO₂, and number of filled grains/panicle and yields/plant (g). Cluster analysis based on 22 traits grouped the 43 rice genotypes into five clusters. Cluster II was the largest and consisted of 20 genotypes mostly originating from the Philippines. The first four principle components of 22 traits accounted for about 72% of the total variation and indicated a wide variation among the genotypes. The selected best trait of the number of filled grains/panicle and yields/plant (g), which showed high heritability and high genetic advance, could be used as a selection criterion for hybridisation programmes in the future.

  20. 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.

  1. Characterization of Leaf Photosynthetic Properties for No-Tillage Rice

    Institute of Scientific and Technical Information of China (English)

    CHEN Song; XIA Guo-mian; ZHAO Wei-ming; WU Fei-bo; ZHANG Guo-ping

    2007-01-01

    A study was conducted to determine the influence of no-tillage cultivation on leaf photosynthesis of rice plants under field conditions. Experiments with the treatments, no-tillage and conventional tillage were carried out at three locations (Jiaxing, Hangzhou,and Xiaoshan, Zhejiang Province, China) for two years (2005 and 2006). Grain yield was constant in Jiaxing, but slightly higher in Hangzhou and Xiaoshan under no-tillage cultivation than that under conventional cultivation. In comparison with the conventional cultivation, no-tillage cultivation showed less biomass accumulation before heading and higher capacity of matter production during grain filling. A significantly higher leaf net photosynthetic rate was observed for the plants under no-tillage than for those under conventional tillage. The fluorescence parameter (Fv/Fm) in leaf did not show any difference between the two cultivations. The effect of cultivation management on transpiration rate (Tr) and SPAD value of rice leaf was dependent on the location and year.

  2. Quantum delocalization directs antenna absorption to photosynthetic reaction centers

    CERN Document Server

    Caycedo-Soler, Felipe; Autenrieth, Caroline; Ghosh, Robin; Huelga, Susana F; Plenio, Martin B

    2015-01-01

    Photosynthesis -- the conversion of sunlight to chemical energy -- is fundamental for supporting life on our planet. Despite its importance, the physical principles that underpin the primary steps of photosynthesis, from photon absorption to electronic charge separation, remain to be understood in full. Previously, electronic coherence within tightly-packed light-harvesting (LH) units or within individual reaction centers (RCs) has been recognized as an important ingredient for a complete understanding of the excitation energy transfer dynamics. However, the electronic coherence across RC and LH units has been consistently neglected as it does not play a significant role during these relatively slow transfer processes. Here, we turn our attention to the absorption process, which occurs on much shorter timescales. We demonstrate that the - often overlooked - spatially extended but short-lived excitonic delocalization across RC and LH units plays a relevant role in general photosynthetic systems, as it causes a...

  3. An extended model for electron spin polarization in photosynthetic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Morris, A.L.; Norris, J.R. (Argonne National Lab., IL (USA) Chicago Univ., IL (USA). Dept. of Chemistry); Thurnauer, M.C. (Argonne National Lab., IL (USA))

    1990-01-01

    We have developed a general model for electron spin polarization which includes contributions from both CIDEP (chemically induced dynamic electron polarization) and CRP (correlated radical polarization). In this paper, we apply this model to sequential electron transfer in photosynthetic bacteria. Our model calculates the density matrix for the P{sup +}I{sup {minus}} radical pair and transfers the polarization as it develops to the P{sup +}Q{sup {minus}} radical pair. We illustrate several possible cases. One case is equivalent to CIDEP; no interactions are included on the secondary radical pair, P{sup +}Q{sup {minus}}. Another approximates CRPP by either increasing the transfer rate from P{sup +}I{sup {minus}} to P{sup +}Q{sup {minus}} or restricting interactions to the secondary radical pair, P{sup +}Q{sup {minus}}. Others allow interactions on both the primary and secondary radical pairs with various transfer rates. 15 refs., 4 figs.

  4. Vibration-assisted resonance in photosynthetic excitation energy transfer

    CERN Document Server

    Irish, E K; Lovett, B W

    2013-01-01

    Coherent quantum energy transfer, as observed in photosynthetic pigment-protein complexes, is inhibited by energetic disorder. While this difficulty can be overcome to some extent by the addition of environmental noise, it has recently has begun to be appreciated that discrete intra- and/or intermolecular vibrational modes may play an important role in quantum dynamics. We present a microscopic mechanism by which intramolecular vibrational modes create resonant energy transfer pathways, enhancing the efficiency of both coherent and dephasing-assisted transfer. The principles of this vibration-assisted resonance are illustrated in a simple model based on one energy-transfer branch of the well-characterised Fenna-Matthews-Olson complex. Despite its simplicity, this model captures the interplay between strong electronic coupling that produces delocalised exciton states and resonance-enhanced weak coupling to local vibrational modes. Analytical and numerical results show that intramolecular vibrations can enhance...

  5. 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

  6. Interplay between coherence and decoherence in LHCII photosynthetic complex

    CERN Document Server

    Giorda, Paolo; Zanardi, Paolo; Lloyd, Seth

    2011-01-01

    This paper investigates the dynamics of excitonic transport in photocomplex LHCII, the primary component of the photosynthetic apparatus in green plants. The dynamics exhibits a strong interplay between coherent processes mediated by the excitonic Hamiltonian, and incoherent processes due to interactions with the environment. The spreading of the exciton over a single monomer is well described by a proper measure of delocalization that allows one to identify two relevant time scales. An exciton initially localized in one chromophore first spreads coherently to neighboring chromophores. During this initial coherent spreading, quantum effects such as entanglement play a role. As the effects of a decohering environment come into play, coherence and decoherence interact to give rise to efficient and robust excitonic transport, reaching a maximum efficiency at the levels of decoherence found in physiological conditions. We analyze the efficiency for different possible topologies (monomer, dimer, trimer, tetramer) ...

  7. 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...

  8. Limits of quantum speedup in photosynthetic light harvesting

    CERN Document Server

    Hoyer, Stephan; Whaley, K Birgitta

    2009-01-01

    In the initial stages of photosynthesis, energy collected from light is transferred across a network of chlorophyll molecules to a reaction center. Recent experimental evidence showing long lived quantum coherences in this energy transport in several photosynthetic light-harvesting complexes has suggested that coherence may play an important role in the function of these systems. In particular, it has been hypothesized that excitation transport in such systems may feature speedups analogous to those found in quantum algorithms. The most direct analogy to such transport is found in quantum walks, which form the basis of a powerful class of quantum algorithms including quantum search. Unlike idealized quantum walks, however, real light harvesting complexes are characterized by disorder, energy funnels and decoherence. Whether any quantum speedup can be found in this situation is unclear. Here we characterize quantum speedup for excitation energy transfer in the Fenna-Matthews-Olson (FMO) complex of green sulfur...

  9. Quantum Coherent Dynamics at Ambient Temperature in Photosynthetic Molecules

    CERN Document Server

    Walters, Zachary B

    2011-01-01

    Photosynthetic antenna complexes are responsible for absorbing energy from sunlight and transmitting it to remote locations where it can be stored. Recent experiments have found that this process involves long-lived quantum coherence between pigment molecules, called chromophores, which make up these complexes. Expected to decay within 100 fs at room temperature, these coherences were instead found to persist for picosecond time scales, despite having no apparent isolation from the thermal environment of the cell. This paper derives a quantum master equation which describes the coherent evolution of a system in strong contact with a thermal environment. Conditions necessary for long coherence lifetimes are identified, and the role of coherence in efficient energy transport is illuminated. Static spectra and exciton transfer rates for the PE545 complex of the cryptophyte algae CS24 are calculated and shown to have good agreement with experiment.

  10. 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.

  11. Factors influencing the purification efficiency of photosynthetic bacteria

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    One strain of photosynthetic bacteria (PSB) was isolated from substrate sludge offresh-water fishpond. Influence of the use level of PSB culture solution, illumination condition,temperature, salinity, the use level of copper sulfate and dipterex on the purification efficiency was investigated. The results showed that the optimum use level of PSB culture solution was 10 mg/L,and the purification efficiency at illumination was higher than that at black, and if the temperature was lower than 15℃, or the use level of sodium chloride, copper sulfate and dipterex were higherthan 10 000 mg/L, 0.4 mg/L and 2.0 mg/L, respectively, the purification efficiency dropped distinctly.

  12. Quantum entanglement phenomena in photosynthetic light harvesting complexes

    CERN Document Server

    Whaley, K Birgitta; Ishizaki, Akihito

    2010-01-01

    We review recent theoretical calculations of quantum entanglement in photosynthetic light harvesting complexes. These works establish, for the first time, a manifestation of this characteristically quantum mechanical phenomenon in biologically functional structures. We begin by summarizing calculations on model biomolecular systems that aim to reveal non-trivial characteristics of quantum entanglement in non-equilibrium biological environments. We then discuss and compare several calculations performed recently of excitonic dynamics in the Fenna-Matthews-Olson light harvesting complex and of the entanglement present in this widely studied pigment-protein structure. We point out the commonalities between the derived results and also identify and explain the differences. We also discuss recent work that examines entanglement in the structurally more intricate light harvesting complex II (LHCII). During this overview, we take the opportunity to clarify several subtle issues relating to entanglement in such biomo...

  13. Characterization of Leaf Photosynthetic Properties for No-Tillage Rice

    Directory of Open Access Journals (Sweden)

    Song CHEN

    2007-12-01

    Full Text Available A study was conducted to determine the influence of no-tillage cultivation on leaf photosynthesis of rice plants under field conditions. Experiments with the treatments, no-tillage and conventional tillage were carried out at three locations (Jiaxing, Hangzhou, and Xiaoshan, Zhejiang Province, China for two years (2005 and 2006. Grain yield was constant in Jiaxing, but slightly higher in Hangzhou and Xiaoshan under no-tillage cultivation than that under conventional cultivation. In comparison with the conventional cultivation, no-tillage cultivation showed less biomass accumulation before heading and higher capacity of matter production during grain filling. A significantly higher leaf net photosynthetic rate was observed for the plants under no-tillage than for those under conventional tillage. The fluorescence parameter (Fv/Fm in leaf did not show any difference between the two cultivations. The effect of cultivation management on transpiration rate (Tr and SPAD value of rice leaf was dependent on the location and year.

  14. Synthetic Biology with Cytochromes P450 Using Photosynthetic Chassis

    DEFF Research Database (Denmark)

    Gnanasekaran, Thiyagarajan

    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......, 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......’s atmosphere and anthropogenic carbon dioxide (CO2) increase in the atmosphere. Hence, tapping into photosynthesis for synthetic biology endeavor is very rational, and for future, it has a huge potential for the industrial production of fuels and high value bioactive compounds in a sustainable way. Most...

  15. New thioredoxin targets in the unicellular photosynthetic eukaryote Chlamydomonas reinhardtii

    Science.gov (United States)

    Lemaire, Stéphane D.; Guillon, Blanche; Le Maréchal, Pierre; Keryer, Eliane; Miginiac-Maslow, Myroslawa; Decottignies, Paulette

    2004-01-01

    Proteomics were used to identify the proteins from the eukaryotic unicellular green alga Chlamydomonas reinhardtii that can be reduced by thioredoxin. These proteins were retained specifically on a thioredoxin affinity column made of a monocysteinic thioredoxin mutant able to form mixed disulfides with its targets. Of a total of 55 identified targets, 29 had been found previously in higher plants or Synechocystis, but 26 were new targets. Biochemical tests were performed on three of them, showing a thioredoxin-dependent activation of isocitrate lyase and isopropylmalate dehydrogenase and a thioredoxin-dependent deactivation of catalase that is redox insensitive in Arabidopsis. In addition, we identified a Ran protein, a previously uncharacterized nuclear target in a photosynthetic organism. The metabolic and evolutionary implications of these findings are discussed. PMID:15123830

  16. Ultrafast transient absorption spectroscopy: principles and application to photosynthetic systems.

    Science.gov (United States)

    Berera, Rudi; van Grondelle, Rienk; Kennis, John T M

    2009-01-01

    The photophysical and photochemical reactions, after light absorption by a photosynthetic pigment-protein complex, are among the fastest events in biology, taking place on timescales ranging from tens of femtoseconds to a few nanoseconds. The advent of ultrafast laser systems that produce pulses with femtosecond duration opened up a new area of research and enabled investigation of these photophysical and photochemical reactions in real time. Here, we provide a basic description of the ultrafast transient absorption technique, the laser and wavelength-conversion equipment, the transient absorption setup, and the collection of transient absorption data. Recent applications of ultrafast transient absorption spectroscopy on systems with increasing degree of complexity, from biomimetic light-harvesting systems to natural light-harvesting antennas, are presented. In particular, we will discuss, in this educational review, how a molecular understanding of the light-harvesting and photoprotective functions of carotenoids in photosynthesis is accomplished through the application of ultrafast transient absorption spectroscopy.

  17. Photosynthetic biomineralization of radioactive Sr via microalgal CO2 absorption.

    Science.gov (United States)

    Lee, Seung Yeop; Jung, Kwang-Hwan; Lee, Ju Eun; Lee, Keon Ah; Lee, Sang-Hyo; Lee, Ji Young; Lee, Jae Kwang; Jeong, Jong Tae; Lee, Seung-Yop

    2014-11-01

    Water-soluble radiostrontium ((90)Sr) was efficiently removed as a carbonate form through microalgal photosynthetic process. The immobilization of soluble (90)Sr radionuclide and production of highly-precipitable radio-strontianite ((90)SrCO3) biomineral are achieved by using Chlorella vulgaris, and the biologically induced mineralization drastically decreased the (90)Sr radioactivity in water to make the highest (90)Sr removal ever reported. The high-resolution microscopy revealed that the short-term removal of soluble (90)Sr by C. vulgaris was attributable to the rapid and selective carbonation of (90)Sr together with the consumption of dissolved CO2 during photosynthesis. A small amount of carbonate in water could act as Sr(2+) sinks through the particular ability of the microalga to make the carbonate mineral of Sr stabilized firmly at the surface site.

  18. Personality Traits, Learning and Academic Achievements

    Science.gov (United States)

    Jensen, Mikael

    2015-01-01

    There has been an increased interest in personality traits (especially the five-factor model) in relation to education and learning over the last decade. Previous studies have shown a relation between personality traits and learning, and between personality traits and academic achievement. The latter is typically described in terms of Grade Point…

  19. A trait database for marine copepods

    DEFF Research Database (Denmark)

    Brun, Philipp Georg; Payne, Mark; Kiørboe, Thomas

    2017-01-01

    The trait-based approach is gaining increasing popularity in marine plankton ecology but the field urgently needs more and easier accessible trait data to advance.We compiled trait information on marine pelagic copepods, a major group of zooplankton, from the published literature and from experts...

  20. Extracellular production of tellurium nanoparticles by the photosynthetic bacterium Rhodobacter capsulatus

    Energy Technology Data Exchange (ETDEWEB)

    Borghese, Roberto, E-mail: roberto.borghese@unibo.it [Dept. of Pharmacy and Biotechnology, University of Bologna (Italy); Brucale, Marco [Institute for the Study of Nanostructured Materials (CNR-ISMN), Rome (Italy); Fortunato, Gianuario [Dept. of Pharmacy and Biotechnology, University of Bologna (Italy); Lanzi, Massimiliano [Dept. of Industrial Chemistry “Toso Montanari”, University of Bologna (Italy); Mezzi, Alessio [Institute for the Study of Nanostructured Materials (CNR-ISMN), Rome (Italy); Valle, Francesco; Cavallini, Massimiliano [Institute for the Study of Nanostructured Materials (CNR-ISMN), Bologna (Italy); Zannoni, Davide [Dept. of Pharmacy and Biotechnology, University of Bologna (Italy)

    2016-05-15

    Highlights: • Tellurite is reduced by R. capsulatus as cytosolic tellurium nanoprecipitates TeNPs. • Lawsone allows R. capsulatus to produce extracellular TeNPs. • Extracellular TeNPs production depends on the carbon source used for cells growth. • Both lawsone concentration and the incubation time determine the TeNPs size. • Extracellular TeNPs are coated with extracellular polymeric substances (EPS). - Abstract: The toxic oxyanion tellurite (TeO{sub 3}{sup 2−}) is acquired by cells of Rhodobacter capsulatus grown anaerobically in the light, via acetate permease ActP2 and then reduced to Te{sup 0} in the cytoplasm as needle-like black precipitates. Interestingly, photosynthetic cultures of R. capsulatus can also generate Te{sup 0} nanoprecipitates (TeNPs) outside the cells upon addition of the redox mediator lawsone (2-hydroxy-1,4-naphtoquinone). TeNPs generation kinetics were monitored to define the optimal conditions to produce TeNPs as a function of various carbon sources and lawsone concentration. We report that growing cultures over a 10 days period with daily additions of 1 mM tellurite led to the accumulation in the growth medium of TeNPs with dimensions from 200 up to 600–700 nm in length as determined by atomic force microscopy (AFM). This result suggests that nucleation of TeNPs takes place over the entire cell growth period although the addition of new tellurium Te{sup 0} to pre-formed TeNPs is the main strategy used by R. capsulatus to generate TeNPs outside the cells. Finally, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) analysis of TeNPs indicate they are coated with an organic material which keeps the particles in solution in aqueous solvents.

  1. Reprint of “Extracellular production of tellurium nanoparticles by the photosynthetic bacterium Rhodobacter capsulatus”

    Energy Technology Data Exchange (ETDEWEB)

    Borghese, Roberto, E-mail: roberto.borghese@unibo.it [Dept. of Pharmacy and Biotechnology, University of Bologna (Italy); Brucale, Marco [Institute for the Study of Nanostructured Materials (CNR-ISMN), Rome (Italy); Fortunato, Gianuario [Dept. of Pharmacy and Biotechnology, University of Bologna (Italy); Lanzi, Massimiliano [Dept. of Industrial Chemistry “Toso Montanari”, University of Bologna (Italy); Mezzi, Alessio [Institute for the Study of Nanostructured Materials (CNR-ISMN), Rome (Italy); Valle, Francesco; Cavallini, Massimiliano [Institute for the Study of Nanostructured Materials (CNR-ISMN), Bologna (Italy); Zannoni, Davide [Dept. of Pharmacy and Biotechnology, University of Bologna (Italy)

    2017-02-15

    Highlights: • Tellurite is reduced by R. capsulatus as cytosolic tellurium nanoprecipitates TeNPs. • Lawsone allows R. capsulatus to produce extracellular TeNPs. • Extracellular TeNPs production depends on the carbon source used for cells growth. • Both lawsone concentration and the incubation time determine the TeNPs size. • Extracellular TeNPs are coated with extracellular polymeric substances (EPS). - Abstract: The toxic oxyanion tellurite (TeO{sub 3}{sup 2−}) is acquired by cells of Rhodobacter capsulatus grown anaerobically in the light, via acetate permease ActP2 and then reduced to Te{sup 0} in the cytoplasm as needle-like black precipitates. Interestingly, photosynthetic cultures of R. capsulatus can also generate Te{sup 0} nanoprecipitates (TeNPs) outside the cells upon addition of the redox mediator lawsone (2-hydroxy-1,4-naphtoquinone). TeNPs generation kinetics were monitored to define the optimal conditions to produce TeNPs as a function of various carbon sources and lawsone concentration. We report that growing cultures over a 10 days period with daily additions of 1 mM tellurite led to the accumulation in the growth medium of TeNPs with dimensions from 200 up to 600–700 nm in length as determined by atomic force microscopy (AFM). This result suggests that nucleation of TeNPs takes place over the entire cell growth period although the addition of new tellurium Te{sup 0} to pre-formed TeNPs is the main strategy used by R. capsulatus to generate TeNPs outside the cells. Finally, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) analysis of TeNPs indicate they are coated with an organic material which keeps the particles in solution in aqueous solvents.

  2. Subcortical infarction resulting in acquired stuttering.

    Science.gov (United States)

    Ciabarra, A M; Elkind, M S; Roberts, J K; Marshall, R S

    2000-10-01

    Stuttering is an uncommon presentation of acute stroke. Reported cases have often been associated with left sided cortical lesions, aphasia, and difficulties with other non-linguistic tests of rhythmic motor control. Three patients with subcortical lesions resulting in stuttering are discussed. In one patient the ability to perform time estimations with a computerised repetitive time estimation task was characterised. One patient had a pontine infarct with clinical evidence of cerebellar dysfunction. A second patient had a left basal ganglionic infarct and a disruption of timing estimation. A third patient had a left subcortical infarct and a mild aphasia. These findings expand the reported distribution of infarction that can result in acquired stuttering. Subcortical mechanisms of speech control and timing may contribute to the pathophysiology of acquired stuttering.

  3. Acquired portosystemic collaterals: anatomy and imaging*

    Science.gov (United States)

    Leite, Andréa Farias de Melo; Mota Jr., Américo; Chagas-Neto, Francisco Abaeté; Teixeira, Sara Reis; Elias Junior, Jorge; Muglia, Valdair Francisco

    2016-01-01

    Portosystemic shunts are enlarged vessels that form collateral pathological pathways between the splanchnic circulation and the systemic circulation. Although their causes are multifactorial, portosystemic shunts all have one mechanism in common-increased portal venous pressure, which diverts the blood flow from the gastrointestinal tract to the systemic circulation. Congenital and acquired collateral pathways have both been described in the literature. The aim of this pictorial essay was to discuss the distinct anatomic and imaging features of portosystemic shunts, as well as to provide a robust method of differentiating between acquired portosystemic shunts and similar pathologies, through the use of illustrations and schematic drawings. Imaging of portosystemic shunts provides subclinical markers of increased portal venous pressure. Therefore, radiologists play a crucial role in the identification of portosystemic shunts. Early detection of portosystemic shunts can allow ample time to perform endovascular shunt operations, which can relieve portal hypertension and prevent acute or chronic complications in at-risk patient populations. PMID:27777479

  4. Acquired versus familial demyelinative neuropathies in children.

    Science.gov (United States)

    Miller, R G; Gutmann, L; Lewis, R A; Sumner, A J

    1985-01-01

    The electrophysiologic differences between chronic acquired demyelinative neuropathy and the demyelinative form of Charcot-Marie-Tooth disease have recently been reported. The present report extends these observations to include the genetically determined demyelinating neuropathies seen in metachromatic leukodystrophy, Krabbe's leukodystrophy, and Cockayne's syndrome. The electrophysiologic features of metachromatic leukodystrophy (five patients), Krabbe's (four patients), and Cockayne's syndrome (three patients) were all similar. There was uniform slowing of conduction (both in different nerves and in different nerve segments), and conduction block was not seen. These findings are consistent with a uniform degree of demyelination in multiple nerves and throughout the entire length of individual axons. Thus, uniform slowing of nerve conduction constitutes strong evidence for a familial demyelinative neuropathy, as opposed to the multifocal slowing seen in acute and chronic acquired demyelinative neuropathy.

  5. Acquired portosystemic collaterals: anatomy and imaging

    Energy Technology Data Exchange (ETDEWEB)

    Leite, Andrea Farias de Melo; Mota Junior, Americo, E-mail: andreafariasm@gmail.com [Instituto de Medicina Integral Professor Fernando Figueira de Pernambuco (IMIP), Recife, PE (Brazil); Chagas-Neto, Francisco Abaete [Universidade de Fortaleza (UNIFOR), Fortaleza, CE (Brazil); Teixeira, Sara Reis; Elias Junior, Jorge; Muglia, Valdair Francisco [Universidade de Sao Paulo (FMRP/USP), Ribeirao Preto, SP (Brazil). Faculdade de Medicina

    2016-07-15

    Portosystemic shunts are enlarged vessels that form collateral pathological pathways between the splanchnic circulation and the systemic circulation. Although their causes are multifactorial, portosystemic shunts all have one mechanism in common - increased portal venous pressure, which diverts the blood flow from the gastrointestinal tract to the systemic circulation. Congenital and acquired collateral pathways have both been described in the literature. The aim of this pictorial essay was to discuss the distinct anatomic and imaging features of portosystemic shunts, as well as to provide a robust method of differentiating between acquired portosystemic shunts and similar pathologies, through the use of illustrations and schematic drawings. Imaging of portosystemic shunts provides subclinical markers of increased portal venous pressure. Therefore, radiologists play a crucial role in the identification of portosystemic shunts. Early detection of portosystemic shunts can allow ample time to perform endovascular shunt operations, which can relieve portal hypertension and prevent acute or chronic complications in at-risk patient populations. (author)

  6. Recognising and managing community-acquired pneumonia.

    Science.gov (United States)

    Gibson, Vanessa

    2015-11-18

    Pneumonia remains a significant cause of morbidity and mortality in the UK and yet the seriousness of the disease is underestimated. Pneumonia can be life-threatening because the delicate tissues of the alveoli and pulmonary capillaries are susceptible to damage from the inflammatory response. This damage leads to consolidation that prevents the diffusion of oxygen and carbon dioxide, and this in turn can lead to respiratory failure. This article summarises guidance on the diagnosis and management of community-acquired pneumonia, and also includes information on the prevention of pneumonia. This information should be valuable to nurses working in a variety of clinical areas since patients with community-acquired pneumonia are encountered in primary, intermediate, secondary and critical care.

  7. Quantitative trait loci for flowering time and morphological traits in multiple populations of Brassica rapa

    NARCIS (Netherlands)

    Lou, P.; Jianjun Zhao, Jianjun; Kim, J.S.; Shen, Shuxing; Pino del Carpio, D.; Song, Xiaofei; Jin, M.; Vreugdenhil, D.; Wang, Xiaowu; Koornneef, M.; Bonnema, A.B.

    2007-01-01

    Wide variation for morphological traits exists in Brassica rapa and the genetic basis of this morphological variation is largely unknown. Here is a report on quantitative trait loci (QTL) analysis of flowering time, seed and pod traits, growth-related traits, leaf morphology, and turnip formation in

  8. Quantitative trait loci for flowering time and morphological traits in multiple populations of Brassica rapa

    NARCIS (Netherlands)

    Lou, P.; Jianjun Zhao, Jianjun; Kim, J.S.; Shen, Shuxing; Pino del Carpio, D.; Song, Xiaofei; Jin, M.; Vreugdenhil, D.; Wang, Xiaowu; Koornneef, M.; Bonnema, A.B.

    2007-01-01

    Wide variation for morphological traits exists in Brassica rapa and the genetic basis of this morphological variation is largely unknown. Here is a report on quantitative trait loci (QTL) analysis of flowering time, seed and pod traits, growth-related traits, leaf morphology, and turnip formation in

  9. 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 ...

  10. Assembly of Photosynthetic Antenna Protein Complexes from Algae for Development of Nano-biodevice and Its Fuelization

    Science.gov (United States)

    2013-05-20

    Task 1 : Artificial domain assembly of LH pigment complexes from photosynthetic bacterial membranes on nano-patterning and lipid modified...public release; distribution unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT The purpose of this proposal is to use photosynthetic antenna pigment ...nanobiophotonics) and its fuelization. The advantage of these pigment complexes from algae as well as from plants and photosynthetic bacteria is its

  11. Acquired antibiotic resistance genes: an overview.

    Directory of Open Access Journals (Sweden)

    Angela H.A.M. van Hoek

    2011-09-01

    Full Text Available In this review an overview is given on antibiotic resistance mechanisms with special attentions to the antibiotic resistance genes described so far preceded by a short introduction on the discovery and mode of action of the different classes of antibiotics. As this review is only dealing with acquired resistance, attention is paid to mobile genetic elements such as plasmids, transposons and integrons, which are associated with antibiotic resistance genes, and involved in the dispersal of antimicrobial determinants between different bacteria.

  12. Acquired antibiotic resistance genes: an overview.

    OpenAIRE

    Hoek, Angela H.A.M. van; Dik eMevius; Beatriz eGuerra; Peter eMullany; Adam Paul Roberts; Aarts, Henk J. M.

    2011-01-01

    In this review an overview is given on antibiotic resistance mechanisms with special attentions to the antibiotic resistance genes described so far preceded by a short introduction on the discovery and mode of action of the different classes of antibiotics. As this review is only dealing with acquired resistance, attention is paid to mobile genetic elements such as plasmids, transposons and integrons, which are associated with antibiotic resistance genes, and involved in the dispersal of anti...

  13. Acquired Antibiotic Resistance Genes: An Overview

    OpenAIRE

    Hoek, Angela H.A.M. van; Mevius, Dik; Guerra, Beatriz; Mullany, Peter; Roberts, Adam Paul; Aarts, Henk J. M.

    2011-01-01

    In this review an overview is given on antibiotic resistance (AR) mechanisms with special attentions to the AR genes described so far preceded by a short introduction on the discovery and mode of action of the different classes of antibiotics. As this review is only dealing with acquired resistance, attention is also paid to mobile genetic elements such as plasmids, transposons, and integrons, which are associated with AR genes, and involved in the dispersal of antimicrobial determinants betw...

  14. The pathophysiology of acquired premature ejaculation

    OpenAIRE

    McMahon, Chris G; Jannini, Emmanuele A.; Serefoglu, Ege C.; Hellstrom, Wayne J.G.

    2016-01-01

    The second Ad Hoc International Society for Sexual Medicine (ISSM) Committee for the Definition of Premature Ejaculation defined acquired premature ejaculation (PE) as a male sexual dysfunction characterized by a the development of a clinically significant and bothersome reduction in ejaculation latency time in men with previous normal ejaculatory experiences, often to about 3 minutes or less, the inability to delay ejaculation on all or nearly all vaginal penetrations, and the presence of ne...

  15. Earth Knowledge Acquired by Middle School Students

    Science.gov (United States)

    Ride, Sally

    2008-01-01

    Earth Knowledge Acquired by Middle School Students (EarthKAM), an education activity, allows middle school students to program a digital camera on board the International Space Station to photograph a variety of geographical targets for study in the classroom. Photos are made available on the web for viewing and study by participating schools around the world. Educators use the images for projects involving Earth Science, geography, physics, and social science.

  16. The evolution of costly acquired immune memory.

    Science.gov (United States)

    Best, Alex; Hoyle, Andy

    2013-07-01

    A key feature of the vertebrate adaptive immune system is acquired immune memory, whereby hosts launch a faster and heightened response when challenged by previously encountered pathogens, preventing full infection. Here, we use a mathematical model to explore the role of ecological and epidemiological processes in shaping selection for costly acquired immune memory. Applying the framework of adaptive dynamics to the classic SIR (Susceptible-Infected-Recovered) epidemiological model, we focus on the conditions that may lead hosts to evolve high levels of immunity. Linking our work to previous theory, we show how investment in immune memory may be greatest at long or intermediate host lifespans depending on whether immunity is long lasting. High initial costs to gain immunity are also found to be essential for a highly effective immune memory. We also find that high disease infectivity and sterility, but intermediate virulence and immune period, increase selection for immunity. Diversity in host populations through evolutionary branching is found to be possible but only for a limited range of parameter space. Our model suggests that specific ecological and epidemiological conditions have to be met for acquired immune memory to evolve.

  17. Acquired Factor VIII Inhibitors: Three Cases

    Directory of Open Access Journals (Sweden)

    Tay Za Kyaw

    2013-03-01

    Full Text Available Acquired hemophilia A is a rare, but devastating bleeding disorder caused by spontaneous development of autoantibodies directed against coagulation factor VIII. In 40%-50% of patients it is associated with such conditions as the postpartum period, malignancy, use of medications, and autoimmune diseases; however, its cause is unknown in most cases. Acquired hemophilia A should be suspected in patients that present with a coagulation abnormality, and a negative personal and family history of bleeding. Herein we report 3 patients with acquired hemophilia A that had different underlying pathologies, clinical presentations, and therapeutic responses. Factor VIII inhibitor formation in case 1 occurred 6 months after giving birth; underlying disorders were not identified in cases 2 or 3. The bleeding phenotype in these patients’ ranged from no bleeding tendency with isolated prolongation of APTT (activated partial thromboplastin time to severe intramuscular hematoma and hemarthrosis necessitating recombinant activated factor VII infusion and blood components transfusion. Variable responses to immunosuppressive treatment were also observed.

  18. The pathophysiology of acquired premature ejaculation.

    Science.gov (United States)

    McMahon, Chris G; Jannini, Emmanuele A; Serefoglu, Ege C; Hellstrom, Wayne J G

    2016-08-01

    The second Ad Hoc International Society for Sexual Medicine (ISSM) Committee for the Definition of Premature Ejaculation defined acquired premature ejaculation (PE) as a male sexual dysfunction characterized by a the development of a clinically significant and bothersome reduction in ejaculation latency time in men with previous normal ejaculatory experiences, often to about 3 minutes or less, the inability to delay ejaculation on all or nearly all vaginal penetrations, and the presence of negative personal consequences, such as distress, bother, frustration and/or the avoidance of sexual intimacy. The literature contains a diverse range of biological and psychological etiological theories. Acquired PE is commonly due to sexual performance anxiety, psychological or relationship problems, erectile dysfunction (ED), and occasionally prostatitis and hyperthyroidism, consistent with the predominant organic etiology of acquired PE, men with this complaint are usually older, have a higher mean BMI and a greater incidence of comorbid disease including hypertension, sexual desire disorder, diabetes mellitus, chronic prostatitis, and ED compared to lifelong, variable and subjective PE.

  19. MRI of fetal acquired brain lesions

    Energy Technology Data Exchange (ETDEWEB)

    Prayer, Daniela [Department of Radiodiagnostics, Medical University of Vienna (Austria)]. E-mail: daniela.prayer@meduniwien.ac.at; Brugger, Peter C. [Center of Anatomy and Cell Biology, Medical University of Vienna (Austria); Kasprian, Gregor [Department of Radiodiagnostics, Medical University of Vienna (Austria); Witzani, Linde [Department of Radiodiagnostics, Medical University of Vienna (Austria); Helmer, Hanns [Department of Obstetrics and Gynecology, Medical University of Vienna (Austria); Dietrich, Wolfgang [Department of Neurosurgery, Medical University of Vienna (Austria); Eppel, Wolfgang [Department of Obstetrics and Gynecology, Medical University of Vienna (Austria); Langer, Martin [Department of Obstetrics and Gynecology, Medical University of Vienna (Austria)

    2006-02-15

    Acquired fetal brain damage is suspected in cases of destruction of previously normally formed tissue, the primary cause of which is hypoxia. Fetal brain damage may occur as a consequence of acute or chronic maternal diseases, with acute diseases causing impairment of oxygen delivery to the fetal brain, and chronic diseases interfering with normal, placental development. Infections, metabolic diseases, feto-fetal transfusion syndrome, toxic agents, mechanical traumatic events, iatrogenic accidents, and space-occupying lesions may also qualify as pathologic conditions that initiate intrauterine brain damage. MR manifestations of acute fetal brain injury (such as hemorrhage or acute ischemic lesions) can easily be recognized, as they are hardly different from postnatal lesions. The availability of diffusion-weighted sequences enhances the sensitivity in recognizing acute ischemic lesions. Recent hemorrhages are usually readily depicted on T2 (*) sequences, where they display hypointense signals. Chronic fetal brain injury may be characterized by nonspecific changes that must be attributable to the presence of an acquired cerebral pathology. The workup in suspected acquired fetal brain injury also includes the assessment of extra-CNS organs that may be affected by an underlying pathology. Finally, the placenta, as the organ that mediates oxygen delivery from the maternal circulation to the fetus, must be examined on MR images.

  20. MRI of fetal acquired brain lesions.

    Science.gov (United States)

    Prayer, Daniela; Brugger, Peter C; Kasprian, Gregor; Witzani, Linde; Helmer, Hanns; Dietrich, Wolfgang; Eppel, Wolfgang; Langer, Martin

    2006-02-01

    Acquired fetal brain damage is suspected in cases of destruction of previously normally formed tissue, the primary cause of which is hypoxia. Fetal brain damage may occur as a consequence of acute or chronic maternal diseases, with acute diseases causing impairment of oxygen delivery to the fetal brain, and chronic diseases interfering with normal, placental development. Infections, metabolic diseases, feto-fetal transfusion syndrome, toxic agents, mechanical traumatic events, iatrogenic accidents, and space-occupying lesions may also qualify as pathologic conditions that initiate intrauterine brain damage. MR manifestations of acute fetal brain injury (such as hemorrhage or acute ischemic lesions) can easily be recognized, as they are hardly different from postnatal lesions. The availability of diffusion-weighted sequences enhances the sensitivity in recognizing acute ischemic lesions. Recent hemorrhages are usually readily depicted on T2 (*) sequences, where they display hypointense signals. Chronic fetal brain injury may be characterized by nonspecific changes that must be attributable to the presence of an acquired cerebral pathology. The workup in suspected acquired fetal brain injury also includes the assessment of extra-CNS organs that may be affected by an underlying pathology. Finally, the placenta, as the organ that mediates oxygen delivery from the maternal circulation to the fetus, must be examined on MR images.