WorldWideScience

Sample records for chlorophyll fluorescence signals

  1. Interpreting chlorophyll fluorescence signals: the effects of leaf age

    Science.gov (United States)

    Albert, L.; Vergeli, P.; Martins, G.; Saleska, S. R.; Huxman, T. E.

    2015-12-01

    Remote sensing of sun-induced chlorophyll fluorescence (SIF) promises robust estimation of carbon uptake across landscapes, as studies of plant physiology have shown that fluorescence emission is directly linked to photosynthesis at the leaf level. Yet most leaf-level studies demonstrating the link between chlorophyll fluorescence and photosynthesis have studied leaves in their prime: leaves that recently finished expansion and have yet to senesce. By contrast, remote sensing of landscapes involves observing leaves of different ages. For example, broadleaf deciduous forests and annual plant communities in temperate regions have leaves that develop and then senesce over the course of a growing season. In this experiment, we explored how leaf age and moisture availability affect steady-state fluoresence (Fs) at the leaf level. We simultaneously measured net photosynthesis (Anet) and Fs for leaves of known ages on greenhouse-grown dwarf Helianthus Annuus (sunflowers) from two watering treatments. To monitor plant water status, we measured pre-dawn water potential, and, for a subset of leaves, osmotic potential. Fully expanded or near-fully expanded leaves (~8 to ~23 days old) had higher Anet at saturating light than young, expanding leaves (less than 8 days old) or old leaves nearing senescence (>23 days old). We found a positive relationship between Fs and Anet, suggesting that the link between fluorescence emission and photosynthesis is robust across leaves of different ages. However, leaf age had marked effects on the light response curve of photosynthesis and fluorescence metrics. These results suggest that leaf age distribution, and changes in leaf age distribution due to phenology, should be considered when interpreting SIF at the landscape level.

  2. Spectral and physiological information from chlorophyll fluorescence signals in the detection of pine damage

    Energy Technology Data Exchange (ETDEWEB)

    Meinander, O. [Finnish Meteorological Inst., Helsinki (Finland). Air Quality Dept.; Somersalo, S. [Helsinki Univ., Helsinki (Finland). Dept. of Plant Biology

    1995-12-31

    Photosynthesis is often among the first targets of the air pollution stress of plants. As chlorophyll fluorescence is a process competing with photosynthetic electron transport it can be employed to study the potential photosynthetic capacity and to detect damage to the photosynthetic apparatus. Many previous studies have shown that chlorophyll fluorescence can be a powerful tool in the detection of forest damage. In this preliminary study, singular value analysis of the fluorescence induction curves was used together with the traditional way of analyzing fluorescence measurements. The experimental data were collected from ozone and carbon dioxide fumigated Scots pine saplings. (author)

  3. Chlorophyll fluorescence emission spectrum inside a leaf

    OpenAIRE

    Pedrós Esteban, Roberto; Moya, Ismael; Goulas, Yves; Jacquemoud, Stéphane

    2008-01-01

    Chlorophyll a fluorescence can be used as an early stress indicator. Fluorescence is also connected to photosynthesis so it can be proposed for global monitoring of vegetation status from a satellite platform. Nevertheless, the correct interpretation of fluorescence requires accurate physical models. The spectral shape of the leaf fluorescence free of any re-absorption effect plays a key role in the models and is difficult to measure. We present a vegetation fluorescence emission spectrum fre...

  4. Bowel perforation detection using metabolic fluorescent chlorophylls

    Science.gov (United States)

    Han, Jung Hyun; Jo, Young Goun; Kim, Jung Chul; Choi, Sujeong; Kang, Hoonsoo; Kim, Yong-Chul; Hwang, In-Wook

    2016-03-01

    Thus far, there have been tries of detection of disease using fluorescent materials. We introduce the chlorophyll derivatives from food plants, which have longer-wavelength emissions (at >650 nm) than those of fluorescence of tissues and organs, for detection of bowel perforation. To figure out the possibility of fluorescence spectroscopy as a monitoring sensor of bowel perforation, fluorescence from organs of rodent models, intestinal and peritoneal fluids of rodent models and human were analyzed. In IVIS fluorescence image of rodent abdominal organ, visualization of perforated area only was possible when threshold of image is extremely finely controlled. Generally, both perforated area of bowel and normal bowel which filled with large amount of chlorophyll derivatives were visualized with fluorescence. The fluorescence from chlorophyll derivatives penetrated through the normal bowel wall makes difficult to distinguish perforation area from normal bowel with direct visualization of fluorescence. However, intestinal fluids containing chlorophyll derivatives from food contents can leak from perforation sites in situation of bowel perforation. It may show brighter and longer-wavelength regime emissions of chlorophyll derivatives than those of pure peritoneal fluid or bioorgans. Peritoneal fluid mixed with intestinal fluids show much brighter emissions in longer wavelength (at>650 nm) than those of pure peritoneal fluid. In addition, irrigation fluid, which is used for the cleansing of organ and peritoneal cavity, made of mixed intestinal and peritoneal fluid diluted with physiologic saline also can be monitored bowel perforation during surgery.

  5. Detection of the onset of glyphosate-induced soybean plant injury through chlorophyll fluorescence signal extraction and measurement

    Science.gov (United States)

    Zhao, Feng; Guo, Yiqing; Huang, Yanbo; Reddy, Krishna N.; Zhao, Yanhua; Molin, William T.

    2015-01-01

    In this study, chlorophyll fluorescence (ChlF) was used to detect the onset of soybean plant injury from treatment of glyphosate, the most widely used herbicide. Thirty-six pots of nonglyphosate-resistant soybean were randomly divided into three groups and treated with different doses of glyphosate solutions. The three treatment groups were control (CTRL) group (with no glyphosate treatment), 0.25X group (treated with 0.217 kg.ae/ha solution of glyphosate), and 0.5X group (treated with 0.433 kg.ae/ha solution of glyphosate). Three kinds of fluorescence measurements, steady-state fluorescence spectra, Kautsky effect parameters, and ChlF-related spectral indices were extracted and generated from the measurements in the glyphosate treatment experiment. The mean values of these fluorescence measurements for each of the CTRL group, the 0.25X group, and the 0.5X group were calculated. Glyphosate-induced leaf injury was then analyzed by examining the separability of these mean values at 6, 24, 48, and 72 hours after the treatment (HAT). Results indicate that the peak position of far-red ChlF shows an obvious blue shift for glyphosate-treated soybean, and peak values of steady-state fluorescence spectra for the three groups can be significantly distinguished from each other at 48 HAT and later. Four Kautsky effect parameters, Fv, Fv/Fm, Area, and PI, are parameters sensitive to glyphosate treatment, showing some differences between the CTRL group and treated groups at 24 HAT, and significant differences among the three groups at and beyond 48 HAT. Moreover, ChlF-related spectral indices, R6832/(R675.R690) and R690/R655, are also shown to be useful in detection of the glyphosate injury, though they are less effective than the steady-state fluorescence spectra and the Kautsky effect parameters. Based on the presented results, it can be concluded that glyphosate-induced soybean injury can be detected in a timely manner by the ChlF measurements, and this method has the

  6. Measurement of Sun Induced Chlorophyll Fluorescence Using Hyperspectral Satellite Imagery

    Science.gov (United States)

    Irteza, S. M.; Nichol, J. E.

    2016-06-01

    Solar Induced Chlorophyll Fluorescence (SIF), can be used as an indicator of stress in vegetation. Several scientific approaches have been made and there is considerable evidence that steady state Chlorophyll fluorescence is an accurate indicator of plant stress hence a reliable tool to monitor vegetation health status. Retrieval of Chlorophyll fluorescence provides an insight into photochemical and carbon sequestration processes within vegetation. Detection of Chlorophyll fluorescence has been well understood in the laboratory and field measurement. Fluorescence retrieval methods were applied in and around the atmospheric absorption bands 02B (Red wavelength) approximately 690 nm and 02A (Far red wavelengths) 740 nm. Hyperion satellite images were acquired for the years 2012 to 2015 in different seasons. Atmospheric corrections were applied using the 6S Model. The Fraunhofer Line Discrimanator (FLD) method was applied for retrieval of SIF from the Hyperion images by measuring the signal around the absorption bands in both vegetated and non vegetated land cover types. Absorption values were extracted in all the selected bands and the fluorescence signal was detected. The relationships between NDVI and Fluorescence derived from the satellite images are investigated to understand vegetation response within the absorption bands.

  7. Phytoplankton productivity quantified from chlorophyll fluorescence

    DEFF Research Database (Denmark)

    Hancke, Kasper; Dalsgaard, Tage; Sejr, Mikael Kristian;

    Phytoplankton are the main food source for marine life, and accurate uantification of its productivity is essential for understanding how marine food webs function. As a novel non-invasive technology, chlorophyll fluorescence can be used to assess in situ primary production in phytoplankton...

  8. Salt stress change chlorophyll fluorescence in mango

    Directory of Open Access Journals (Sweden)

    Cicero Cartaxo de Lucena

    2012-12-01

    Full Text Available This study evaluated the tolerance of mango cultivars 'Haden', 'Palmer', 'Tommy Atkins' and 'Uba' grafted on rootstock 'Imbú' to salt stress using chlorophyll fluorescence. Plants were grown in modified Hoagland solution containing 0, 15, 30, and 45 mmol L-1 NaCl. At 97 days the parameters of the chlorophyll fluorescence (F0, Fm, Fv, F0/Fm, Fv/Fm, Fv'/Fm', ΦPSII = [(Fm'-Fs/(Fm'], D = (1- Fv'/Fm' and ETR = (ΦPSII×PPF×0,84×0,5 were determined. At 100 days, the leaf emission and leaf area, toxicity and leaf abscission indexes were determined. In all cultivars evaluated, in different degree, there were decreases in photochemical efficiency of photosystem II, enhanced concentrations from 15 mmol L-1 NaCl. The decreases in the potential quantum yield of photosystem II (Fv/Fm were 27.9, 18.7, 20.5, and 27.4%, for cultivars 'Haden', 'Palmer', 'Tommy Atkins', and 'Uba', respectively, when grown in 45 mmol L-1 NaCl. It was found decreases in leaf emission and mean leaf area in all cultivars from 15 mmol L-1 NaCl. There were increases in leaf toxicity of 33.0, 67.5, 41.6 and 80.8% and in leaf abscission of 71.8, 29.2, 32.5, and 67.9% for the cultivars 'Haden', 'Palmer', 'Tommy Atkins', and 'Uba' respectively, when grown in 45 mmol L-1 NaCl. Leaf toxicity and leaf abscission were not observed in 15 mmol L-1 NaCl. The decrease in Fv/Fm ratio were accompanied by decreasing in leaf emission and increased leaf toxicity index, showing, therefore, the potential of chlorophyll fluorescence in the early detection of salt stress in mango tree.

  9. Chlorophyll a + b content and chlorophyll fluorescence in avocado

    Science.gov (United States)

    One Tonnage (T) and one Simmonds (S) avocado tree and four TxS crosses were evaluated for differences in chlorophyll content and maximal quantum yield of photosystem II in sun and shade-type leaves. Total chlorophyll content by area (Chl a+bar) ranged from 981 mg m-2 in TxS240 to 4339 mg m-2 in Simm...

  10. Modulated Chlorophyll "a" Fluorescence: A Tool for Teaching Photosynthesis

    Science.gov (United States)

    Marques da Silva, Jorge; Bernardes da Silva, Anabela; Padua, Mario

    2007-01-01

    "In vivo" chlorophyll "a" fluorescence is a key technique in photosynthesis research. The recent release of a low cost, commercial, modulated fluorometer enables this powerful technology to be used in education. Modulated chlorophyll a fluorescence measurement "in vivo" is here proposed as a tool to demonstrate basic photosynthesis phenomena to…

  11. A model for chlorophyll fluorescence and photosynthesis at leaf scale

    NARCIS (Netherlands)

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

    2009-01-01

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

  12. Chlorophyll a fluorescence and herbicide efficacy, metabolism and selectivity

    DEFF Research Database (Denmark)

    Abbas Poor, Majid

    Analysis of chlorophyll fluorescence induction curve (Kautsky curve) parameters was used for the study of the efficacy, metabolism and selectivity of ACCase, PSII and EPSPS inhibitors. Fv/Fm, Fvj and area above Kautsky curve and maximum fluorescence were selected among numerous fluorescence...

  13. An overview of remote sensing of chlorophyll fluorescence

    Science.gov (United States)

    Xing, Xiao-Gang; Zhao, Dong-Zhi; Liu, Yu-Guang; Yang, Jian-Hong; Xiu, Peng; Wang, Lin

    2007-03-01

    Besides empirical algorithms with the blue-green ratio, the algorithms based on fluorescence are also important and valid methods for retrieving chlorophyll-a concentration in the ocean waters, especially for Case II waters and the sea with algal blooming. This study reviews the history of initial cognitions, investigations and detailed approaches towards chlorophyll fluorescence, and then introduces the biological mechanism of fluorescence remote sensing and main spectral characteristics such as the positive correlation between fluorescence and chlorophyll concentration, the red shift phenomena. Meanwhile, there exist many influence factors that increase complexity of fluorescence remote sensing, such as fluorescence quantum yield, physiological status of various algae, substances with related optical property in the ocean, atmospheric absorption etc. Based on these cognitions, scientists have found two ways to calculate the amount of fluorescence detected by ocean color sensors: fluorescence line height and reflectance ratio. These two ways are currently the foundation for retrieval of chlorophyl l - a concentration in the ocean. As the in-situ measurements and synchronous satellite data are continuously being accumulated, the fluorescence remote sensing of chlorophyll-a concentration in Case II waters should be recognized more thoroughly and new algorithms could be expected.

  14. The effect of storage temperature of cucumber fruit on chlorophyll fluorescence

    OpenAIRE

    Ryszard Kosson

    2013-01-01

    The effect of three storage temperature levels: 12,5°C, 20°C, and 1,5°C on basic indexes of chlorophyll fluorescence of cucumber fruits was studied. The greenhouse grown cucumber fruits cv. Wiktor F1 were stored in perforated polyethylene bags or without packages. The minimum chlorophyll fluorescence (Fo), maximum chlorophyll fluorescence (Fm), variable chlorophyll fluorescence (Fv) and relative variable fluorescence (Fv/Fm) of the cucumber peel were measured. Relative variable fluorescence ...

  15. Chlorophyll a fluorescence to phenotype wheat genotypes for heat tolerance

    DEFF Research Database (Denmark)

    Sharma, Dew Kumari; Andersen, Sven Bode; Ottosen, Carl-Otto;

    . Chlorophyll a fluorescence has been a versatile tool in photosynthesis research to measure plant responses to various abiotic stresses that affect PSII. We aim to establish a reproducible protocol to measure response of wheat genotypes to high temperature, based on the physiological marker, maximum quantum......%. Our protocol seems to be stable over environments since interaction between genotypes and the three repeated experiments separated in time was not statistically significant. The chlorophyll a fluorescence protocol may enable identification of wheat lines reliably more or less tolerant to heat stress...

  16. Fluorescence bands and chlorophyll a forms

    NARCIS (Netherlands)

    Goedheer, J.C.

    1964-01-01

    Fluorescence spectra were determined at temperatures between 20° and −196° for a number of photosynthetic organisms. Below −90° the single fluorescence maximum around 685 mμ was replaced by a system of three bands, at 686, 696 and 717–720 mμ in algal cells. Cooling usually resulted in a decrease of

  17. Chlorophyll a fluorescence to phenotype wheat genotypes for heat tolerance

    DEFF Research Database (Denmark)

    Sharma, Dew Kumari; Andersen, Sven Bode; Ottosen, Carl-Otto;

    In prospects of global climate change, heat stress is a rising constraint for the productivity of wheat (Triticum aestivum L.). It is a heat-susceptible crop beyond 17-23oC temperature throughout its phenological stages, flowering phase being the most sensitive stage. Chlorophyll a fluorescence...

  18. A new relative referencing method for crop monitoring using chlorophyll fluorescence

    Science.gov (United States)

    Norikane, J.; Goto, E.; Kurata, K.; Takakura, T.

    2003-01-01

    The measurement of plant chlorophyll fluorescence has been used for many years as a method to monitor a plant's health status. These types of methods have been mostly relegated to the laboratory. The newly developed Relative Referencing Method allows for the measurement of chlorophyll fluorescence under artificial lighting conditions. The fluorescence signal can be determined by first taking a reference signal measurement, then a second measurement with an additional fluorescence excitation source. The first signal can then be subtracted from the second and the plant's chlorophyll fluorescence due to the second lighting source can be determined. With this simple approach, a photosynthesizing plant can be monitored to detect signs of water stress. Using this approach experiments on tomato plants have shown that it was possible to detect water stress, while the plants were continuously illuminated by fluorescent lamps. This method is a promising tool for the remote monitoring of crops grown in a CELSS-type application. Published by Elsevier Science Ltd on behalf of COSPAR.

  19. Quenching of chlorophyll fluorescence induced by silver nanoparticles

    Science.gov (United States)

    Queiroz, A. M.; Mezacasa, A. V.; Graciano, D. E.; Falco, W. F.; M'Peko, J.-C.; Guimarães, F. E. G.; Lawson, T.; Colbeck, I.; Oliveira, S. L.; Caires, A. R. L.

    2016-11-01

    The interaction between chlorophyll (Chl) and silver nanoparticles (AgNPs) was evaluated by analyzing the optical behavior of Chl molecules surrounded by different concentrations of AgNPs (10, 60, and 100 nm of diameter). UV-Vis absorption, steady state and time-resolved fluorescence measurements were performed for Chl in the presence and absence of these nanoparticles. AgNPs strongly suppressed the Chl fluorescence intensity at 678 nm. The Stern-Volmer constant (KSV) showed that fluorescence suppression is driven by the dynamic quenching process. In particular, KSV was nanoparticle size-dependent with an exponential decrease as a function of the nanoparticle diameter. Finally, changes in the Chl fluorescence lifetime in the presence of nanoparticles demonstrated that the fluorescence quenching may be induced by the excited electron transfer from the Chl molecules to the metal nanoparticles.

  20. Plant abiotic stress diagnostic by laser induced chlorophyll fluorescence spectral analysis of in vivo leaf tissue of biofuel species

    Science.gov (United States)

    Gouveia-Neto, Artur S.; Silva, Elias A., Jr.; Costa, Ernande B.; Bueno, Luciano A.; Silva, Luciana M. H.; Granja, Manuela M. C.; Medeiros, Maria J. L.; Câmara, Terezinha J. R.; Willadino, Lilia G.

    2010-02-01

    Laser induced fluorescence is exploited to evaluate the effect of abiotic stresses upon the evolution and characteristics of in vivo chlorophyll emission spectra of leaves tissues of brazilian biofuel plants species(Saccharum officinarum and Jatropha curcas). The chlorophyll fluorescence spectra of 20 min predarkened intact leaves were studied employing several excitation wavelengths in the UV-VIS spectral region. Red(Fr) and far-red (FFr) chlorophyll fluorescence emission signals around 685 nm and 735 nm, respectively, were analyzed as a function of the stress intensity and the time of illumination(Kautsky effect). The Chl fluorescence ratio Fr/FFr which is a valuable nondestructive indicator of the chlorophyll content of leaves was investigated during a period of time of 30 days. The dependence of the Chl fluorescence ratio Fr/FFr upon the intensity of the abiotic stress(salinity) was examined. The results indicated that the salinity plays a major hole in the chlorophyll concentration of leaves in both plants spieces, with a significant reduction in the chlorophyll content for NaCl concentrations in the 25 - 200 mM range. The laser induced chlorophyll fluorescence analysis allowed detection of damage caused by salinity in the early stages of the plants growing process, and can be used as an early-warning indicator of salinity stress

  1. Chlorophyll fluorescence analysis and imaging in plant stress and disease

    Energy Technology Data Exchange (ETDEWEB)

    Daley, P.F.

    1994-12-01

    Quantitative analysis of chlorophyll fluorescence transients and quenching has evolved rapidly in the last decade. Instrumentation capable of fluorescence detection in bright actinic light has been used in conjunction with gas exchange analysis to build an empirical foundation relating quenching parameters to photosynthetic electron transport, the state of the photoapparatus, and carbon fixation. We have developed several instruments that collect video images of chlorophyll fluorescence. Digitized versions of these images can be manipulated as numerical data arrays, supporting generation of quenching maps that represent the spatial distribution of photosynthetic activity in leaves. We have applied this technology to analysis of fluorescence quenching during application of stress hormones, herbicides, physical stresses including drought and sudden changes in humidity of the atmosphere surrounding leaves, and during stomatal oscillations in high CO{sub 2}. We describe a recently completed portable fluorescence imaging system utilizing LED illumination and a consumer-grade camcorder, that will be used in long-term, non-destructive field studies of plant virus infections.

  2. Laser and sunlight-induced fluorescence from chlorophyll pigments

    Science.gov (United States)

    Kim, H. H.; Brown, K. S.

    1986-01-01

    Fluorescence properties of chlorophyll pigment bearing plant foliage utilizing a 337 nm nitrogen laser and integrating sphere were studied. Measured yields, in terms of number of photons emitted per 100 photons absorbed, range from 1.5 to 0.1 for the 685 nm peak, and from 4.2 to 0.2 for the 730 nm peak. Decreasing order of magnitude puts herbaceous leaves ahead of all others followed by broad leaves of hardwoods and coniferous needles. Meaningful quantization for the fluorescence peaks at 430 and 530 nm could not be attained. Passive monitoring of these fluorescence peaks is successful only for the 685 nm from the ocean surface. Field data show the reflectance changes at 685 nm due to the algae presence amounts to 1% at most.

  3. Overview of Global Monitoring of Terrestrial Chlorophyll Fluorescence from Space

    Science.gov (United States)

    Guanter, Luis; Zhang, Yongguang; Kohler, Philipp; Walther, Sophia; Frankenberg, Christian; Joiner, Joanna

    2016-01-01

    Despite the critical importance of photosynthesis for the Earth system, understanding how it is influenced by factors such as climate variability, disturbance history, and water or nutrient availability remains a challenge because of the complex interactions and the lack of GPP measurements at various temporal and spatial scales. Space observations of the sun-induced chlorophyll fluorescence (SIF) electromagnetic signal emitted by plants in the 650-850nm spectral range hold the promise of providing a new view of vegetation photosynthesis on a global basis. Global retrievals of SIF from space have recently been achieved from a number of spaceborne spectrometers originally intended for atmospheric research. Despite not having been designed for land applications, such instruments have turned out to provide the necessary spectral and radiometric sensitivity for SIF retrieval from space. The first global measurements of SIF were achieved in 2011 from spectra acquired by the Japanese GOSAT mission launched in 2009. The retrieval takes advantage of the high spectral resolution provided by GOSATs Fourier Transform Spectrometer (FTS) which allows the evaluation of the in-filling of solar Fraunhofer lines by SIF. Unfortunately, GOSAT only provides a sparse spatial sampling with individual soundings separated by several hundred kilometers. Complementary, the Global Ozone Monitoring Experiment-2 (GOME-2) instruments onboard MetOp-A and MetOp-B enable SIF retrievals since 2007 with a continuous and global spatial coverage. GOME-2 measures in the red and near-infrared (NIR) spectral regions with a spectral resolution of 0.5 nm and a pixel size of up to 40x40 km2. Most recently, another global and spatially continuous data set of SIF retrievals at 740 nm spanning the 2003-2012 time frame has been produced from ENVISATSCIAMACHY. This observational scenario has been completed by the first fluorescence data from the NASA-JPL OCO-2 mission (launched in July 2014) and the upcoming

  4. Fluorescent indices of oak and wheat leaves in dependence on chlorophyll content

    Science.gov (United States)

    Kalmatskaya, Olesya Ð. ń.; Karavaev, Vladimir A.; Gunar, Lyudmila E.

    2016-04-01

    Fluorescence spectra and fluorescence induction curves of the leaves of two plant species in dependence on chlorophyll content were studied. Red oak (Quercus rubra L.) leaves upon the autumn chlorophyll degradation, as well as wheat leaves (Triticum aestivum L.) at various stages of ontogenesis showed linear dependence between the ratio ω = F740 / F685 (the ratio of the maximum values of fluorescence at respective wavelengths) and chlorophyll content. In both cases, parameter Fv / Fm (the relative value of the variable fluorescence) remained almost unchanged up to significant reduction of chlorophyll content, indicating on maintaining the high photochemical activity of photosystem 2.

  5. Models of fluorescence and photosynthesis for interpreting measurements of solar-induced chlorophyll fluorescence

    OpenAIRE

    van der Tol, C.; Berry, J. A.; P. K. E. Campbell; Rascher, U.

    2014-01-01

    We have extended a conventional photosynthesis model to simulate field and laboratory measurements of chlorophyll fluorescence at the leaf scale. The fluorescence paramaterization is based on a close nonlinear relationship between the relative light saturation of photosynthesis and nonradiative energy dissipation in plants of different species. This relationship diverged only among examined data sets under stressed (strongly light saturated) conditions, possibly caused by differences in xanth...

  6. Chlorophyll fluorescence from creosote-exposed plants in mesocosms: Validation of a bioindicator

    Energy Technology Data Exchange (ETDEWEB)

    Marwood, C.A.; Harris, M.L.; Day, K.E.; Greenberg, B.M.; Solomon, K.R. [Univ. of Guelph, Ontario (Canada). Centre for Toxicology

    1995-12-31

    The chlorophyll fluorescence assay is a rapid, sensitive measure of photosynthetic competence in higher plants and algae that can be used to detect the impact of toxicants at many sites in the plant cell. Chlorophyll fluorescence was examined in plants exposed to PAHs as part of a study to validate chlorophyll fluorescence as a bioindicator by correlating effects on fluorescence with population-level effects in outdoor mesocosms. The wood preservative creosote was used as a mixed PAH source. Two species of aquatic plants, Lemna gibba and Myriophyllum sp., were exposed to 0.1--100 uL/L of creosote in 12,000 L artificial ponds. Creosote was introduced into the mesocosms using different dosing schemes to simulate leaching and spill events. The pulse amplitude modulated fluorescence technique was used to measure several parameters from plants in situ during a 60-day exposure. Chlorophyll fluorescence parameters were compared to creosote effects on population-level growth. Chlorophyll fluorescence was inhibited by creosote at concentrations above 3 uL/L, which also caused a similar inhibition of plant growth in the mesocosms. However, chlorophyll fluorescence was more sensitive than growth endpoints at low creosote concentrations. The chlorophyll fluorescence assay also detected damage to the photosynthetic apparatus in plants after only a few days exposure to creosote. Thus, chlorophyll fluorescence from plants exposed to creosote was well correlated with environmentally relevant endpoints at the population level. The effects of the different dosing schemes on creosote toxicity will also be discussed.

  7. Changes of Photosystem Ⅱ Electron Transport in the Chlorophyll-deficient Oilseed Rape Mutant Studied by Chlorophyll Fluorescence and Thermoluminescence

    Institute of Scientific and Technical Information of China (English)

    Jun-Wei Guo; Jin-Kui Guo; Yun Zhao; Lin-Fang Du

    2007-01-01

    The photosystem Ⅱ (PSII) complex of photosynthetic membranes comprises a number of chlorophyll-binding proteins that are important to the electron flow. Here we report that the chlorophyll b-deficient mutant has de creased the amount of light-harvesting complexes with an increased amount of some core polypeptides of PSII,including CP43 and CP47. By means of chlorophyll fluorescence and thermoluminescence, we found that the ratio of Fv/Fm, qP and electron transport rate in the chlorophyll b-deficient mutant was higher compared to the wild type.In the chlorophyll b-deficient mutant, the decay of the primary electron acceptor quinones (QA-) reoxidation was decreased, measured by the fluorescence. Furthermore, the thermolumlnescence studies in the chlorophyll b deficient mutant showed that the B band (S2/S3QB-) decreased slightly and shifted up towards higher temperatures.In the presence of dichlorophenyl-dimethylurea, which is inhibited in the electron flow to the second electron acceptor quinines (QB) at the PSII acceptor side, the maximum of the Q band (S2QA-) was decreased slightly and shifted down to lower temperatures, compared to the wild type. Thus, the electron flow within PSll of the chlorophyll b-deficient mutant was down-regulated and characterized by faster oxidation of the primary electron acceptor quinine QA- via forward electron flow and slower reduction of the oxidation S states.

  8. Photosynthesis, chlorophyll fluorescence characteristics, and chlorophyll content of soybean seedlings under combined stress of bisphenol A and cadmium.

    Science.gov (United States)

    Hu, Huiqing; Wang, Lihong; Wang, Qingqing; Jiao, Liya; Hua, Weiqi; Zhou, Qing; Huang, Xiaohua

    2014-11-01

    Bisphenol A (BPA) is ubiquitous in the environment because of its continual application in plastics and the epoxy resin industry. Cadmium (Cd) is a highly toxic heavy metal element mainly used in smelting, electroplating, and plastic and dye manufacturing. Pollution as a result of BPA and Cd exists simultaneously in many agricultural regions. However, little information is available regarding the combined effects of BPA and Cd on plants. The combined effects of BPA and Cd on the photosynthesis, chlorophyll fluorescence, and chlorophyll content of soybean seedlings were investigated using noninvasive technology. Combined treatment with 1.5 mg/L BPA and 0.2 mg/L Cd synergistically improved the net photosynthetic rate (Pn ), initial fluorescence (F0 ), maximal photochemical efficiency (Fv /Fm ), effective quantum yield of photosystem II (ΦPSII ), photosynthetic electron transport rate (ETR), and chlorophyll content. Combined treatment with 1.5 mg/L BPA and 3.0 mg/L Cd increased the F0 and decreased the Pn , Fv /Fm , ΦPSII , and ETR, whereas BPA and Cd exhibited an antagonistic effect. Furthermore, combined treatment with 17.2/50.0 mg/L BPA and 3.0/10.0 mg/L Cd synergistically decreased the Pn , Fv /Fm , ΦPSII , ETR, and chlorophyll content, although it increased the F0 . Finally, the effects of BPA and Cd on photosynthesis, chlorophyll fluorescence, and chlorophyll content ceased when BPA stress was stopped.

  9. Canopy Level Chlorophyll Fluorescence and the PRI in a Cornfield

    Science.gov (United States)

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

    2012-01-01

    Two bio-indicators, the Photochemical Reflectance Index (PRI) and solar-induced red and far-red Chlorophyll Fluorescence (SIF), were derived from directional hyperspectral observations and studied in a cornfield on two contrasting days in the growing season. Both red and far-red SIF exhibited higher values on the day when the canopy in the early senescent stage, but only the far-red SIF showed sensitivity to viewing geometry. Consequently, the red/far-red SIF ratio varied greatly among azimuth positions while the largest values were obtained for the "hotspot" at both growth stages. This ratio was lower (approx.0.88 +/- 0.4) in early July than in August when the ratio approached equivalence (near approx.1). In concert, the PRI exhibited stronger responses to both zenith and azimuth angles and different values on the two growth stages. The potential of using these indices to monitor photosynthetic activities needs further investigation

  10. Effects of LEDs on chlorophyll fluorescence and secondary metabolites in Phalaenopsis

    DEFF Research Database (Denmark)

    Ouzounis, T.; Fretté, X.; Rosenqvist, Eva;

    2015-01-01

    of the experiment. Chlorophyll fluorescence was also recorded with PAM-2001. Leaf area and total fresh weight were highest in the 40%B/60%R for Phalaenopsis 'Vivien', while 100%R demonstrated the highest leaf area and fresh weight for Phalaenopsis 'Purple star'. Chlorophyll fluorescence for the same treatments...

  11. Contribution of Chlorophyll Fluorescence to the Apparent Reflectance of Vegetation

    Science.gov (United States)

    Campbell, P. K. Entcheva; Middleton, E. M.; Kim, M. S.

    2007-01-01

    Current strategies for monitoring the physiologic status of terrestrial vegetation rely on remote sensing reflectance (R) measurements, whi ch provide estimates of relative vegetation vigor based primarily on chlorophyll content. Vegetation chlorophyll fluorescence (CF) offers a non-destructive alternative and a more direct approach for diagnosis of vegetation stress before a significant reduction in chlorophyll content has occurred. Thus, monitoring of vegetation vigor based on CF may allow earlier stress detection and more accurate carbon sequestra tion estimates, than is possible using R data alone. However, the observed apparent vegetation reflectance (Ra) in reality includes contrib utions from both the reflected and fluoresced radiation. The aim of t his study is to determine the relative R and CF fractions contributing to Ra from the vegetation in the red to near-infrared region of the spectrum. The practical objectives of the study are to: 1) evaluate t he relationship between CF and R at the foliar level for corn, soybean, maple; and 2) for corn, determine if the relationship established f or healthy (optimal N) vegetation changes under N defiiency. To obtai n generally applicable results, experimental measurements were conducted on unrelated crop and tree species (maple, soybean and corn), unde r controlled conditions and a gradient of inorganic N fertilization l evels. Optical R spectra and actively induced CF emissions were obtained on the same foliar samples, in conjunction with measurements of p hotosynthetic function, pigment levels, and C and N content. The comm on spectral trends or similarities were examined. On average, 10-20% of apparent R at 685 nm was actually due to CF. The spectral trends in steady and maximum F varied significantly, with Fs (especially red) showing higher ability for species and treatment separation. The relative contribution of ChF to R varied significantly among species, with maple emitting much higher F amounts, as

  12. Water deficit and salt stress diagnosis through LED induced chlorophyll fluorescence analysis in Jatropha curcas L. oil plants for biodiesel

    Science.gov (United States)

    Gouveia-Neto, Artur S.; Silva, Elias A., Jr.; Oliveira, Ronaldo A.; Cunha, Patrícia C.; Costa, Ernande B.; Câmara, Terezinha J. R.; Willadino, Lilia G.

    2011-02-01

    Light-emitting-diode induced chlorophyll fluorescence analysis is employed to investigate the effect of water and salt stress upon the growth process of physicnut(jatropha curcas) grain oil plants for biofuel. Red(Fr) and far-red (FFr) chlorophyll fluorescence emission signals around 685 nm and 735 nm, respectively, were observed and examined as a function of the stress intensity(salt concentration and water deficit) for a period of time of 30 days. The chlorophyll fluorescence(ChlF) ratio Fr/FFr which is a valuable nondestructive and nonintrusive indicator of the chlorophyll content of leaves was exploited to monitor the level of stress experienced by the jatropha plants. The ChlF technique data indicated that salinity plays a minor role in the chlorophyll concentration of leaves tissues for NaCl concentrations in the 25 to 200 mM range, and results agreed quite well with those obtained using conventional destructive spectrophotometric methods. Nevertheless, for higher NaCl concentrations a noticeable decrease in the Chl content was observed. The Chl fluorescence ratio analysis also permitted detection of damage caused by water deficit in the early stages of the plants growing process. A significant variation of the Fr/FFr ratio was observed sample in the first 10 days of the experiment when one compared control and nonwatered samples. The results suggest that the technique may potentially be applied as an early-warning indicator of stress caused by water deficit.

  13. [Study on the characters of phytoplankton chlorophyll fluorescence excitation spectra based on fourth-derivative].

    Science.gov (United States)

    Lu, Lu; Su, Rong-Guo; Wang, Xiu-Lin; Zhu, Chen-Jian

    2007-11-01

    Chlorophyll fluorescence excitation spectra of six phytoplankton species, belonging to Bacillariophyta and Dinophyta, were dealt by fourth-derivative analysis with the Matlab program. The results show that between 350 nm and 550 nm six fluorescence peaks were found in the fourth-derivative spectra, which are representatives of non-pigments, chlorophylls and carotenoides respectively. The method makes Bacillariophyta and Dinophyta more distinguishable when the fourth-derivative spectra are compared with the chlorophyll fluorescence excitation spectra. It can be used not only to discriminate the two groups of algaes, but also to reduce the effect of noise. The fluorescence peaks in the fourth-derivative spectra are proved to be stable.

  14. From the shape of the vertical profile of in vivo fluorescence to Chlorophyll-a concentration

    Directory of Open Access Journals (Sweden)

    J. Ras

    2011-08-01

    Full Text Available In vivo fluorescence of Chlorophyll-a (Chl-a is a potentially useful property to study the vertical distribution of phytoplankton biomass. However the technique is presently not fully exploited as it should be, essentially because of the difficulties in converting the fluorescence signal into an accurate Chl-a concentration. These difficulties arise noticeably from natural variations in the Chl-a fluorescence relationship, which is under the control of community composition as well as of their nutrient and light status. As a consequence, although vertical profiles of fluorescence are likely the most recorded biological property in the open ocean, the corresponding large databases are underexploited. Here with the aim to convert a fluorescence profile into a Chl-a concentration profile, we test the hypothesis that the Chl-a concentration can be gathered from the sole knowledge of the shape of the fluorescence profile. We analyze a large dataset from 18 oceanographic cruises conducted in case-1 waters from the highly stratified hyperoligotrophic waters (surface Chl-a = 0.02 mg m−3 of the South Pacific Gyre to the eutrophic waters of the Benguela upwelling (surface Chl-a = 32 mg m−3 and including the very deep mixed waters in the North Atlantic (Mixed Layer Depth = 690 m. This dataset encompasses more than 700 vertical profiles of Chl-a fluorescence as well as accurate estimations of Chl-a by High Performance Liquid Chromatography (HPLC. Two typical fluorescence profiles are identified, the uniform profile, characterized by a homogeneous layer roughly corresponding to the mixed layer, and the non-uniform profile, characterized by the presence of a Deep Chlorophyll Maximum. Using appropriate mathematical parameterizations, a fluorescence profile is subsequently represented by 3 or 5 shape parameters for uniform or non-uniform profiles, respectively. For both situations, an empirical model is developed to predict the "true" Chl-a concentration

  15. From the shape of the vertical profile of in vivo fluorescence to Chlorophyll-a concentration

    Science.gov (United States)

    Mignot, A.; Claustre, H.; D'Ortenzio, F.; Xing, X.; Poteau, A.; Ras, J.

    2011-08-01

    In vivo fluorescence of Chlorophyll-a (Chl-a) is a potentially useful property to study the vertical distribution of phytoplankton biomass. However the technique is presently not fully exploited as it should be, essentially because of the difficulties in converting the fluorescence signal into an accurate Chl-a concentration. These difficulties arise noticeably from natural variations in the Chl-a fluorescence relationship, which is under the control of community composition as well as of their nutrient and light status. As a consequence, although vertical profiles of fluorescence are likely the most recorded biological property in the open ocean, the corresponding large databases are underexploited. Here with the aim to convert a fluorescence profile into a Chl-a concentration profile, we test the hypothesis that the Chl-a concentration can be gathered from the sole knowledge of the shape of the fluorescence profile. We analyze a large dataset from 18 oceanographic cruises conducted in case-1 waters from the highly stratified hyperoligotrophic waters (surface Chl-a = 0.02 mg m-3) of the South Pacific Gyre to the eutrophic waters of the Benguela upwelling (surface Chl-a = 32 mg m-3) and including the very deep mixed waters in the North Atlantic (Mixed Layer Depth = 690 m). This dataset encompasses more than 700 vertical profiles of Chl-a fluorescence as well as accurate estimations of Chl-a by High Performance Liquid Chromatography (HPLC). Two typical fluorescence profiles are identified, the uniform profile, characterized by a homogeneous layer roughly corresponding to the mixed layer, and the non-uniform profile, characterized by the presence of a Deep Chlorophyll Maximum. Using appropriate mathematical parameterizations, a fluorescence profile is subsequently represented by 3 or 5 shape parameters for uniform or non-uniform profiles, respectively. For both situations, an empirical model is developed to predict the "true" Chl-a concentration from these shape

  16. Impact of petrochemicals on the photosynthesis of Halophila ovalis using chlorophyll fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Ralph, P.J.; Burchett, M.D. [University of Sydney (Australia). Institute for Coastal Resource Management and Dept. of of Environmental Biology and Horticulture

    1998-06-01

    Laboratory-cultured Halophila ovalis showed tolerance to petrochemical exposure up to 1% (w/v) solution of Bass Strait crude oil, an oil dispersant (Corexit 9527) and a mixture of crude oil and dispersant. Quantum yield, as measured by chlorophyll fluorescence, was the most sensitive measure of the photosynthetic processes affected by petrochemical. The results indicated clearly that chlorophyll fluorescence was effective at monitoring the onset and development of stress and recovery of H. ovalis when exposed to crude oil, dispersant and a mixture of the two compounds. Photosynthetic pigment content generally confirmed the chlorophyll fluorescence response; however, several anomalies occurred. (author)

  17. Chlorophyll content and chlorophyll fluorescence in tomato leaves infested with an invasive mealybug, Phenacoccus solenopsis (Hemiptera: Pseudococcidae).

    Science.gov (United States)

    Huang, Jun; Zhang, Peng-Jun; Zhang, Juan; Lu, Yao-Bin; Huang, Fang; Li, Ming-Jiang

    2013-10-01

    Herbivore injury has indirect effects on the growth and performance of host plants through photosynthetic suppression. It causes uncertain reduction in photosynthesis, which likely depends on the degree of infestation. Rapid light curves provide detailed information on the saturation characteristics of electron transport as well as the overall photosynthetic performance of a plant. We examined the effects of different intensities of infestation of the invasive mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), on the relative chlorophyll content and rapid light curves of tomato Solanum lycopersicum L. leaves using a chlorophyll meter and chlorophyll fluorescence measurement system, respectively, under greenhouse conditions. After 38 d of P. solenopsis feeding, relative chlorophyll content of tomato plants with initial high of P. solenopsis was reduced by 57.3%. Light utilization efficiency (α) for the initial high-density treatment was reduced by 42.4%. However, no significant difference between initial low-density treatment and uninfested control was found. The values of the maximum electron transport rate and minimum saturating irradiance for initial high-density treatment were reduced by 82.0 and 69.7%, respectively, whereas the corresponding values for low-density treatment were reduced by 55.9 and 58.1%, respectively. These data indicated that changes were induced by P. solenopsis feeding in the relative chlorophyll content and chlorophyll fluorescence of infested tomato plants. The results indicating that low initial infestation by P. solenopsis caused no change in relative leaf chlorophyll content or light utilization efficiency could have been because the plants rapidly adapted to P. solenopsis feeding or because of compensatory photosynthesis.

  18. Study of plant fluorescence prop erties based on laser-induced chlorophyll fluorescence lifetime imaging technology%基于激光诱导叶绿素荧光寿命成像技术的植物荧光特性研究∗

    Institute of Scientific and Technical Information of China (English)

    万文博; 华灯鑫; 乐静; 闫哲; 周春艳

    2015-01-01

    Plant fluorescence is a susceptible signal in plant fluorescence remote sensing detection. In order to solve this problem, a technique for plant chlorophyll fluorescence lifetime imaging is presented to evaluate living status for plant growth and environmental monitoring. A concave lens is used to expand laser beam at a wavelength of 355 nm, and the living plant is exposed in this laser light source to excite chlorophyll fluorescence. And the chlorophyll fluorescence signals are detected by an intensification charge coupled device. Time resolved measurement method is used in this article, so that every time the same fluorescence signals can be excited by the same laser pulse. Meanwhile, the delay time needed for triggering intensification charge coupled device should be changed consecutively, and the whole discrete fluorescence signal can be obtained. The discrete fluorescence signals from the particular location points of the plant are fitted. An improved method of forward iterative deconvolution is used to retrieve the corresponding fluorescence lifetime, and the high-precision fluorescence lifetime can be obtained. Furthermore, the fluorescence lifetime values at all the location points are retrieved to obtain the distribution map of chlorophyll fluorescence lifetime. This method can give the chlorophyll fluorescence image efficiently. The distribution map of fluorescence lifetime can more effectively reflect the plant chlorophyll concentration than the fluorescence intensity image does. The physical property of chlorophyll fluorescence lifetime from living plants has been studied preliminarily, indicating that the plant physiological status is related to its fluorescence lifetime to a certain extent; and the chlorophyll fluorescence lifetime and plant environment have a subtle and complex correlation. In the future, the relationship between chlorophyll fluorescence lifetime and plant environment will be expected to study with the cooperation of biophysicist.

  19. Linking chlorophyll a fluorescence to photosynthesis for remote sensing applications: mechanisms and challenges.

    Science.gov (United States)

    Porcar-Castell, Albert; Tyystjärvi, Esa; Atherton, Jon; van der Tol, Christiaan; Flexas, Jaume; Pfündel, Erhard E; Moreno, Jose; Frankenberg, Christian; Berry, Joseph A

    2014-08-01

    Chlorophyll a fluorescence (ChlF) has been used for decades to study the organization, functioning, and physiology of photosynthesis at the leaf and subcellular levels. ChlF is now measurable from remote sensing platforms. This provides a new optical means to track photosynthesis and gross primary productivity of terrestrial ecosystems. Importantly, the spatiotemporal and methodological context of the new applications is dramatically different compared with most of the available ChlF literature, which raises a number of important considerations. Although we have a good mechanistic understanding of the processes that control the ChlF signal over the short term, the seasonal link between ChlF and photosynthesis remains obscure. Additionally, while the current understanding of in vivo ChlF is based on pulse amplitude-modulated (PAM) measurements, remote sensing applications are based on the measurement of the passive solar-induced chlorophyll fluorescence (SIF), which entails important differences and new challenges that remain to be solved. In this review we introduce and revisit the physical, physiological, and methodological factors that control the leaf-level ChlF signal in the context of the new remote sensing applications. Specifically, we present the basis of photosynthetic acclimation and its optical signals, we introduce the physical and physiological basis of ChlF from the molecular to the leaf level and beyond, and we introduce and compare PAM and SIF methodology. Finally, we evaluate and identify the challenges that still remain to be answered in order to consolidate our mechanistic understanding of the remotely sensed SIF signal.

  20. Detection of Fluorescence from Single Chlorophyll a Molecules Absorbed on Glass Surface

    Institute of Scientific and Technical Information of China (English)

    JI Dong-Mei; HUANG Zheng-Xi; XIA An-Dong

    2005-01-01

    @@ We investigate the single molecule spectroscopy of chlorophyll a molecules on glass surface in N2-saturated environment. The basic photodynamic parameters of chlorophyll a molecules, such as fluorescence lifetime,survival time before photobleaching, on-time, and off-time, are reported. A four-level model is employed to describe the possible dynamics and photobleaching of chlorophyll a upon excitation. Broad distributions in fluorescence lifetimes and survival times are mainly due to the heterogeneities of both molecular conformation and local environment.

  1. Early Water Stress Detection Using Leaf-Level Measurements of Chlorophyll Fluorescence and Temperature Data

    Directory of Open Access Journals (Sweden)

    Zhuoya Ni

    2015-03-01

    Full Text Available The purpose of this paper was to investigate the early water stress in maize using leaf-level measurements of chlorophyll fluorescence and temperature. In this study, a series of diurnal measurements, such as leaf chlorophyll fluorescence (Fs, leaf spectrum, temperature and photosynthetically active radiation (PAR, were conducted for maize during gradient watering and filled watering experiments. Fraunhofer Line Discriminator methods (FLD and 3FLD were used to obtain fluorescence from leaves spectrum. This simulated work using the SCOPE model demonstrated the variations in fluorescence and temperature in stress levels expressed by different stress factors. In the field measurement, the gradient experiment revealed that chlorophyll fluorescence decreased for plants with water stress relative to well-water plants and Tleaf-Tair increased; the filled watering experiment stated that chlorophyll fluorescence of maize under water stress were similar to those of maize under well-watering condition. In addition, the relationships between the Fs, retrieved fluorescence, Tleaf-Tair and water content were analyzed. The Fs determination resulted to the best coefficients of determination for the normalized retrieved fluorescence FLD/PAR (R2 = 0.54, Tleaf-Tair (R2 = 0.48 and water content (R2 = 0.71. The normalized retrieved fluorescence yielded a good coefficient of determination for Tleaf-Tair (R2 = 0.48. This study demonstrated that chlorophyll fluorescence could reflect variations in the physiological states of plants during early water stress, and leaf temperature confirmed the chlorophyll fluorescence analysis results and improved the accuracy of the water stress detection.

  2. Near infrared fluorescent chlorophyll nanoscale liposomes for sentinel lymph node mapping

    Directory of Open Access Journals (Sweden)

    Fan L

    2012-06-01

    Full Text Available Lina Fan,1,* Qiang Wu,1,* Maoquan Chu1,21School of Life Science and Technology, 2The Institute for Advanced Materials and Nano Biomedicine Tongji University, Shanghai, People's Republic of China *These authors contributed equally to this workBackground: Sentinel lymph node (SLN mapping using in vivo near infrared fluorescence imaging has attracted great attention during the past few years. Here we report on the early use of poorly water-soluble chlorophyll with near infrared fluorescence extracted from the leaf of Chimonanthus salicifolius, for mouse axillary SLN mapping.Methods and results: To improve the water solubility and SLN targeting of the chlorophyll, we encapsulated the chlorophyll in nanoscale liposomes. The liposome-coated chlorophyll nanocomposites obtained were spherical in shape and had an average diameter of 21.7 ± 6.0 nm. The nanocomposites dispersed well in water, and in aqueous suspension they exhibited brighter near infrared fluorescence than chlorophyll alone. After incubation of the nanocomposites with normal liver cells (QSG-7701 and macrophage cells (Ana-1 for no more than 48 hours, there was no obvious reduction in cell viability. When the nanocomposites were injected intradermally into the paw of a mouse, the axillary SLN was found to be strongly fluorescent and was easily visualized in real time without a requirement for surgery. The intensity of the near infrared fluorescence emitted by the SLN was obviously brighter than that emitted by the SLN of another mouse that had been intradermally injected with chlorophyll alone.Conclusion: Our data show that the liposome-coated chlorophyll nanocomposites could have great potential for clinical SLN mapping due to their lack of toxicity, bright near infrared fluorescence, and small diameter.Keywords: chlorophyll, liposomes, nanocomposites, near infrared fluorescence, sentinel lymph node mapping

  3. Qtl mapping of wheat doubled haploids for chlorophyll content and chlorophyll fluorescence kinetics under drought stress imposed at anthesis stage

    International Nuclear Information System (INIS)

    Drought stress is one of the major environmental constraints to crop plants including wheat worldwide. Synthetic hexaploid can act as a vehicle for improving crop tolerance against biotic and abiotic stresses. Doubled haploid population consisting of one hundred and forty individuals derived from cross of Opata and SH223 was used in the present study to identify genomic regions associated with various quantitative attributes of physiological nature. Doubled haploid mapping population was phenotyped for chlorophyll content and chlorophyll fluorescence kinetics under control and drought stress imposed at anthesis stage. Genotyping of population was accomplished by utilizing two hundred and sixty one polymorphic Gaterslaben wheat microsatellites and Beltsville agriculture research center simple sequence repeats. Linkage map of doubled haploid population comprising of 19 linkage groups and covering map length of two thousands six hundred and twenty six (2626) cM was constructed using map maker software. Major and minor QTLs associated with quantitative traits were identified using QGene software. Major QTL for chlorophyll content (QTc.wwc-1B-S11) of doubled haploid mapping population under anthesis drought stress was mapped on chromosome 1B and explained 10.09 percent of phenotypic variation at LOD score of 5.5. Seven major and minor QTLs for PCFK of doubled haploids were identified on chromosome 1B, 7A and 7D under control and drought stress at anthesis stage. The identified QTLs are of prime importance for high resolution mapping in synthetic hexaploid wheat. Genomic synteny of doubled haploids was observed with rice chromosome 2, 4, 7 and maize chromosome 7 owing to occurrence of orthologous QTLs for chlorophyll content and chlorophyll fluorescence respectively. (author)

  4. Chlorophyll fluorescence response to water and nitrogen deficit

    Science.gov (United States)

    Cendrero Mateo, Maria del Pilar

    The increasing food demand as well as the need to predict the impact of warming climate on vegetation makes it critical to find the best tools to assess crop production and carbon dioxide (CO2) exchange between the land and atmosphere. Photosynthesis is a good indicator of crop production and CO2 exchange. Chlorophyll fluorescence (ChF) is directly related to photosynthesis. ChF can be measured at leaf-scale using active techniques and at field-scales using passive techniques. The measurement principles of both techniques are different. In this study, three overarching questions about ChF were addressed: Q1) How water, nutrient and ambient light conditions determine the relationships between photosynthesis and ChF? Which is the optimum irradiance level for detecting water and nutrient deficit conditions with ChF? ; Q2) which are the limits within which active and passive techniques are comparable?; and Q3) What is the seasonal relationship between photosynthesis and ChF when nitrogen is the limiting factor? To address these questions, two main experiments were conducted: Exp1) Concurrent photosynthesis and ChF light-response curves were measured in camelina and wheat plants growing under (i) intermediate-light and (ii) high-light conditions respectively. Plant stress was induced by (i) withdrawing water, and (ii) applying different nitrogen levels; and Exp2) coincident active and passive ChF measurements were made in a wheat field under different nitrogen treatments. The results indicated ChF has a direct relationship with photosynthesis when water or nitrogen drives the relationship. This study demonstrates that the light level at which plants were grown was optimum for detecting water and nutrient deficit with ChF. Also, the results showed that for leaf-average-values, active measurements can be used to better understand the daily and seasonal behavior of passive ChF. Further, the seasonal relation between photosynthesis and ChF with nitrogen stress was not a

  5. Two-photon excited fluorescence from higher electronic states of chlorophylls in photosynthetic antenna complexes a new approach to detect strong excitonic chlorophyll a/b coupling

    CERN Document Server

    Leupold, D; Ehlert, J; Irrgang, K D; Renger, G; Lokstein, H

    2002-01-01

    Stepwise two-photon excitation of chlorophyll a and b in the higher plant main light-harvesting complex (LHC II) and the minor complex CP29 (as well as in organic solution) with 100-fs pulses in the Q/sub y/ region results in a weak blue fluorescence. The dependence of the spectral shape of the blue fluorescence on excitation wavelength offers a new approach to elucidate the long-standing problem of the origin of spectral "chlorophyll forms" in pigment-protein complexes, in particular the characterization of chlorophyll a/b-heterodimers. As a first result we present evidence for the existence of strong chlorophyll a/b-interactions (excitonically coupled transitions at 650 and 680 nm) in LHC II at ambient temperature. In comparison with LHC II, the experiments with CP29 provide further evidence that the lowest energy chlorophyll a transition (at ~680 nm) is not excitonically coupled to chlorophyll b. (22 refs).

  6. Salt stress change chlorophyll fluorescence in mango Estresse salino altera a fluorescência da clorofila em mangueira

    OpenAIRE

    Cicero Cartaxo de Lucena; Dalmo Lopes de Siqueira; Hermínia Emilia Prieto Martinez; Paulo Roberto Cecon

    2012-01-01

    This study evaluated the tolerance of mango cultivars 'Haden', 'Palmer', 'Tommy Atkins' and 'Uba' grafted on rootstock 'Imbú' to salt stress using chlorophyll fluorescence. Plants were grown in modified Hoagland solution containing 0, 15, 30, and 45 mmol L-1 NaCl. At 97 days the parameters of the chlorophyll fluorescence (F0, Fm, Fv, F0/Fm, Fv/Fm, Fv'/Fm', ΦPSII = [(Fm'-Fs)/(Fm')], D = (1- Fv'/Fm') and ETR = (ΦPSII×PPF×0,84×0,5) were determined. At 100 days, the leaf emission and le...

  7. PhotoSpec - Ground-based Remote Sensing of Solar-Induced Chlorophyll Fluorescence

    Science.gov (United States)

    Grossmann, K.; Frankenberg, C.; Seibt, U.; Hurlock, S. C.; Pivovaroff, A.; Stutz, J.

    2015-12-01

    Solar-Induced Chlorophyll Fluorescence (SIF) emitted from vegetation can be used as a constraint for photosynthetic activity and is now observable on a global scale from space. However, many issues on a leaf-to-canopy scale remain poorly understood, such as influences on the SIF signal of environmental conditions, water stress, or radiation. Here, we report on the development and characterization of a novel ground-based spectrometer system for measuring SIF from natural ecosystems (http://www.kiss.caltech.edu/study/photosynthesis/technology.html). The instrumental set-up, requirements, and measurement technique are based on decades of experience using Differential Optical Absorption Spectroscopy (DOAS), an established method to measure atmospheric trace gases. The instrument consists of three thermally stabilized commercial spectrometers that are linked to a 2D scanning telescope unit via optical fiber bundles. The spectrometers cover an SIF retrieval wavelength range at high spectral resolution (670 - 780 nm, 0.1 nm FWHM), but also provide moderate resolution spectra (400 - 800 nm, 1.5 nm FWHM) in order to retrieve vegetation indices and the photochemical reflectance index (PRI). In addition to the instrumental set-up, we will show initial results of test and field measurements with the new instrument that examine the diurnal cycle of the SIF signal of different California native and non-native plants and its correlation with CO2 fluxes. Observations were made under different environmental conditions, variable water and nutrient stress, and with different viewing geometries. We also used concurrent observations by a photosynthetically active radiation (PAR) sensor and a portable chlorophyll fluorometer (PAM) to link the SIF signal to plant metabolism and carbon cycling under a range of environmental conditions.

  8. Effect of Phosphatidylcholine on the Steady State Fluorescence of Chlorophyll in Photosystem Ⅱ Particles

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Phosphatidylcholine (PC) accounts for less than 1% of the total lipids in plant photosystem II (PSII) particles.In this experiment, PSII particles were reconstituted with PC to construct PSII-PC vesicles.The effect of PC on the steady state fluorescence of chlorophyll (Chl) in PSII particles was studied.The results show that PC significantly affected the fluorescence intensity, but did not obviously affect the fluorescence emission band peak position.PC also did not obviously affect the absorbance at 436 nm or the amide I band peak position in FT-IR spectroscopy of PSII particles.The results suggest that PC may affect the light energy transfer from the antenna chlorophyll molecules to the reaction center chlorophyll molecule (P680).

  9. Evaluation of chicory seeds maturity by chlorophyll fluorescence imaging

    OpenAIRE

    Ooms, David; Destain, Marie-France

    2011-01-01

    Chicory (Cichorium intybus L.) seed production includes sorting to remove foreign materials and non-viable seeds. A machine vision system was developed to monitor the fluorescence in order to detect the immature chicory seeds. It comprised a monochromatic light source, a highpass filter and a monochromatic CCD camera sensitive to red and infrared. With this device, blue light reflected by the seeds was blocked whilst red fluorescence was measured by the camera. A segmentation a...

  10. Chlorophyll fluorescence as an indicator of plant water status in cotton

    Science.gov (United States)

    Various methods exist for the measurement of plant water status. Plant breeders value methods that are fast and inexpensive lending themselves to the efficient evaluation of large segregating populations. Chlorophyll fluorescence is a parameter commonly measured by plant physiologists when studying ...

  11. Spatial heterogeneity in active chlorophyll fluorescence and PSII activity of coral tissues

    DEFF Research Database (Denmark)

    Ralph, P.J.; Gademann, R.; Larkum, A.W.D.;

    2002-01-01

    Chlorophyll-a fluorescence was measured in six species of coral, using pulse-amplitude-modulated fluorometers employing fibre-optic probes with diameters of 8 mm, 1 mm and 140 µm. The 8-mm probe integrated responses over a large area, giving more weight to coenosarc than polyp tissue for Acropora...

  12. Behavior of Sethoxydim Alone or in Combination with Turnip Oils on Chlorophyll Fluorescence Parameter

    Directory of Open Access Journals (Sweden)

    Hossein HAMMAMI

    2014-03-01

    Full Text Available Sethoxydim is an acetyl-coenzyme A carboxylase (ACCase inhibitor that changed the shape of the chlorophyll fluorescence curve (kautsky curve in wild oat (Avena ludoviciana Durieu. in greenhouse experiment. This experiment was conducted as completely randomized factorial design with three replications at the College of Agriculture, Ferdowsi University of Mashhad, Iran, during 2012. Results of this study revealed that sethoxydim only and plus emulsifiable turnip oil changed the shape of the chlorophyll fluorescence curve (kautsky curve 7 days after spraying. Sethoxydim plus emulsifiable turnip oil changed the shape of the kautsky curve more than for sethoxydim only. We found that in our study the fv/fm (maximum quantum efficiency was closely linked to the fresh and dry weight dose-response. Sethoxydim plus emulsifiable turnip oil proved more rapidly effect on fv/fm in comparison with sethoxydim only. The fresh and dry weight dose-response relationship with fv/fm showed a similar behavior. This study revealed a good relation between fresh and dry weight according with values of 28 DAS and fv/fm 7 DAS. In general, the findings of this study revealed that Fv/Fm is a good parameter for evaluating effect of sethoxydim little time after spraying. Also, this research showed that 4 folds more time for classical screening methods comparing to chlorophyll fluorescence method. Thereupon, classical screening methods may be replaced by chlorophyll fluorescence method in future.

  13. Monitoring cashew seedlings during interactions with the fungus Lasiodiplodia theobromae using chlorophyll fluorescence imaging

    NARCIS (Netherlands)

    Muniz, C.R.; Freire, F.C.O.; Viana, F.M.P.; Cardoso, J.E.; Sousa, C.A.F.; Guedes, M.I.F.; Schoor, van der R.; Jalink, H.

    2014-01-01

    The chlorophyll (Chl) fluorescence imaging technique was applied to cashew seedlings inoculated with the fungus Lasiodiplodia theobromae to assess any disturbances in the photosynthetic apparatus of the plants before the onset of visual symptoms. Two-month-old cashew plants were inoculated with myce

  14. Interregional difference in spring neap variations in stratification and chlorophyll fluorescence during summer in a tidal sea (Yatsushiro Sea, Japan)

    Science.gov (United States)

    Aoki, Kazuhiro; Onitsuka, Goh; Shimizu, Manabu; Matsuo, Hitoshi; Kitadai, Yuuki; Ochiai, Hironori; Yamamoto, Takeshi; Furukawa, Shinpei

    2016-10-01

    Spring neap variations in stratification and chlorophyll fluorescence were studied during the summers of 2011-2014 in a tidal sea (Yatsushiro Sea, Japan) using monitoring data and hydrodynamic models. Vertical profiles of salinity, temperature and chlorophyll fluorescence were collected nearly weekly from nine stations in this sea during the same period. Composite analysis using vertical profiles of density clearly indicated enhancement of the stratification during the neap tide and a vertically mixed water column during the spring tide in the tidal area. Interregional differences were revealed in the variation of chlorophyll fluorescence with the spring neap tidal cycle. More notable increases in chlorophyll fluorescence were observed during the neap tide in the tidal area around the narrow strait than in the inner area. Temporal stratification led to an increase in the chlorophyll fluorescence in the tidal strait during the neap tide.

  15. Effects of Chlorophyll Availability on Fluorescence Components of Photosystems in the ORF469-Deletion Mutant of Cyanobacterium

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    PCR-amplified ORF469 fragment from Synechocystis sp.PCC 6803 was cloned into pUC118 and a construct was made in which part of ORF469 was deleted and replaced by erythromycin resistance cassette.Transformation of wild type strain of Synechocystis sp.PCC 6803 with this construct yielded a mutant in which ORF469 was deleted.In the resulting mutant, the light-independent pathway of chlorophyll biosynthesis was inactivated and availability of chlorophyll was fully dependent on light.When propagated the mutant in dark, the chlorophyll was non-detectable and protochlorophyllide with 645 nm fluorescence emission peak was accumulated.Meanwhile, the fluorescence emission peaks (excited at 435 nm) of thylakoids at 685 nm, 695 nm and 725 nm, which represented relative chlorophyll-binding proteins, disappeared.Upon return of dark-grown ORF469 mutant to the light, greening occurred and chlorophyll was synthesized to assembly fluorescence emission components in photosystems.Newly synthesized chlorophyll combined the fluorescence component of 685 nm at first, then 725 nm and 695 nm at last, which indicates a pecking order for biogenesis of chlorophyll-binding proteins when availability of chlorophyll is limited.The mutant lacking ORF469 in Synechocystis sp.PCC 6803 was suggested as an excellent cyanobacterial system for studies on the interactions between chlorophyll and chlorophyll-binding proteins in photosystems.

  16. Effects of lanthanum nitrate on growth and chlorophyll fluorescence characteristics of Alternanthera philoxeroides under perchlorate stress

    Institute of Scientific and Technical Information of China (English)

    谢寅峰; 蔡贤雷; 刘伟龙; 陶功胜; 陈倩; 张强

    2013-01-01

    To investigate the effects of exogenous lanthanum (La) on Alternanthera philoxeroides (Mart.) Griseb under perchlorate stress, changes in the growth and physiological parameters were investigated in solution culture experiments under controlled condi-tions. Different concentrations of La (NO3)3 were used in our study. It was shown that 0.1 and 0.5 mg/L La3+alleviated the inhibition effect of perchlorate on A. philoxeroides, including relative growth yield, dry weight of different organs, leaf area and root activity. And La3+prevented decline in the relative chlorophyll content and chlorophyll fluorescence parameters including Fv/Fm, Fv'/Fm',ΦPSI and ETR induced by perchlorate stress. Moreover, 0.5 mg/L La3+showed an optimal mitigative effect, while excess La3+(5.0 mg/L) led to synergistic effect on stress. Correlation analysis revealed a significant positive relationship between growth indexes and the chlorophyll fluorescence parameters, root activity and relative chlorophyll content (p<0.05). The results suggested that appropriate concentration of La3+could effectively alleviate growth inhibition and injury of A. philoxeroides caused by perchlorate stress, and the mitigative effect of La3+might be achieved by improving root activity, maintaining chlorophyll content and promoting photochemical efficiency of photosystem II of A. philoxeroides under perchlorate stress.

  17. Algal photosynthetic responses to toxic metals and herbicides assessed by chlorophyll a fluorescence.

    Science.gov (United States)

    Kumar, K Suresh; Dahms, Hans-Uwe; Lee, Jae-Seong; Kim, Hyung Chul; Lee, Won Chan; Shin, Kyung-Hoon

    2014-06-01

    Chlorophyll a fluorescence is established as a rapid, non-intrusive technique to monitor photosynthetic performance of plants and algae, as well as to analyze their protective responses. Apart from its utility in determining the physiological status of photosynthesizers in the natural environment, chlorophyll a fluorescence-based methods are applied in ecophysiological and toxicological studies to examine the effect of environmental changes and pollutants on plants and algae (microalgae and seaweeds). Pollutants or environmental changes cause alteration of the photosynthetic capacity which could be evaluated by fluorescence kinetics. Hence, evaluating key fluorescence parameters and assessing photosynthetic performances would provide an insight regarding the probable causes of changes in photosynthetic performances. This technique quintessentially provides non-invasive determination of changes in the photosynthetic apparatus prior to the appearance of visible damage. It is reliable, economically feasible, time-saving, highly sensitive, versatile, accurate, non-invasive and portable; thereby comprising an excellent alternative for detecting pollution. The present review demonstrates the applicability of chlorophyll a fluorescence in determining photochemical responses of algae exposed to environmental toxicants (such as toxic metals and herbicides).

  18. Towards a merged satellite and in situ fluorescence ocean chlorophyll product

    Directory of Open Access Journals (Sweden)

    H. Lavigne

    2011-12-01

    Full Text Available Understanding the ocean carbon cycle requires a precise assessment of phytoplankton biomass in the oceans. In terms of numbers of observations, satellite data represents the largest available data set. However, as they are limited to surface waters, they have to be merged with in situ observations. Amongst the in situ data, fluorescence profiles constitute the greatest data set available, because fluorometers operate routinely on oceanographic cruise since the seventies. Nevertheless, fluorescence is only a proxy of the Total Chlorophyll-a concentration and a data calibration is required. Calibration issues are, however, source of uncertainty and they have prevented a systematic and wide range exploitation of the fluorescence data set. In particular, very few attempts to standardize the fluorescence data bases exist. Consequently, merged estimations with other data sources (i.e. satellite are lacking.

    We propose a merging method to fill this gap. It consists firstly, in adjusting the fluorescence profile to impose a zero Chlorophyll-a concentration at depth. Secondly, each point of the fluorescence profile is then multiplied by a correction coefficient which forces the Chlorophyll-a integrated content measured on the fluorescence profile to be consistent with the concomitant ocean color observation. The method is close to the approach proposed by Boss et al. (2008 to calibrate fluorescence data of a profiling float, although important differences do exist. To develop and test our approach, in situ data from three open ocean stations (BATS, HOT and DYFAMED were used. Comparison of the so-called "satellite-corrected" fluorescence profiles with concomitant bottle derived estimations of Chlorophyll-a concentration was performed to evaluate the final error, which resulted to be of about 31 %. Comparison with the Boss et al. (2008 method, carried out on a subset of the DYFAMED data set simulating a profiling float

  19. Towards a merged satellite and in situ fluorescence ocean chlorophyll product

    Directory of Open Access Journals (Sweden)

    H. Lavigne

    2012-06-01

    Full Text Available Understanding the ocean carbon cycle requires a precise assessment of phytoplankton biomass in the oceans. In terms of numbers of observations, satellite data represent the largest available data set. However, as they are limited to surface waters, they have to be merged with in situ observations. Amongst the in situ data, fluorescence profiles constitute the greatest data set available, because fluorometers have operated routinely on oceanographic cruises since the 1970s. Nevertheless, fluorescence is only a proxy of the total chlorophyll a concentration and a data calibration is required. Calibration issues are, however, sources of uncertainty, and they have prevented a systematic and wide range exploitation of the fluorescence data set. In particular, very few attempts to standardize the fluorescence databases have been made. Consequently, merged estimations with other data sources (e.g. satellite are lacking.

    We propose a merging method to fill this gap. It consists firstly in adjusting the fluorescence profile to impose a zero chlorophyll a concentration at depth. Secondly, each point of the fluorescence profile is then multiplied by a correction coefficient, which forces the chlorophyll a integrated content measured on the fluorescence profile to be consistent with the concomitant ocean colour observation. The method is close to the approach proposed by Boss et al. (2008 to correct fluorescence data of a profiling float, although important differences do exist. To develop and test our approach, in situ data from three open ocean stations (BATS, HOT and DYFAMED were used. Comparison of the so-called "satellite-corrected" fluorescence profiles with concomitant bottle-derived estimations of chlorophyll a concentration was performed to evaluate the final error (estimated at 31%. Comparison with the Boss et al. (2008 method, using a subset of the DYFAMED data set, demonstrated that the methods have similar

  20. Spectral reflectance, chlorophyll fluorescence and virological investigations of tobacco plants (Nicotiana tabacum L.) infected with Tobacco mosaic virus (TMV)

    Science.gov (United States)

    Krezhova, Dora; Hristova, Dimitrina; Iliev, Ilko; Yanev, Tony

    Application of multispectral remote sensing techniques to plant condition monitoring has been adopted for various purposes. Remote sensing is a reliable tool for detecting signs of vege-tation stress and diseases. Spectral reflectance and chlorophyll fluorescence are functions of tissue optical properties and biological status of the plants, and illumination conditions. The mean reflectance spectrum depends on the relative composition of all the pigments in the leaf including chlorophylls, carotenoids etc. Chlorophyll fluorescence results from the primary re-actions of photosynthesis and during the last decade it finds widening application as a means for revelation of stress and diseases. The changes in chlorophyll function take place before the alteration in chlorophyll content to occur so that changes in the fluorescence signal arise before any visible signs are apparent. The aim of our investigations was to study the development and spreading out of a viral infection on the leaves of two cultivars tobacco plants (Nicotiana tabacum L.) infected with Tobacco mosaic virus (TMV). We applied two remote sensing tech-niques (spectral reflectance and chlorophyll fluorescence measurements) for evaluation of the changes in the optical properties of the plants in accordance to their physiological status. The serological analyses via the Double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) were made with appropriate kits (Leowe, Germany) for quantitative assessment of the concentration of viruses in the plants. The tobacco plants were grown in green house under controlled conditions. The first cultivar Nevrocop 1146 is known as resistive to the TMV, i.e. it shows hypersensitive response. The second cultivar named Krumovgrad is normally sen-sitive to the TMV. At growth stage 4-6 expanded leaf, up to one leaf from 20 plants for each cultivar were inoculated with TMV. The leaves opposite to the infected ones formed the group of control (untreated) leaves. The

  1. Investigation of Leaf Diseases and Estimation of Chlorophyll Concentration in Seven Barley Varieties Using Fluorescence and Hyperspectral Indices

    Directory of Open Access Journals (Sweden)

    Kang Yu

    2013-12-01

    Full Text Available Leaf diseases, such as powdery mildew and leaf rust, frequently infect barley plants and severely affect the economic value of malting barley. Early detection of barley diseases would facilitate the timely application of fungicides. In a field experiment, we investigated the performance of fluorescence and reflectance indices on (1 detecting barley disease risks when no fungicide is applied and (2 estimating leaf chlorophyll concentration (LCC. Leaf fluorescence and canopy reflectance were weekly measured by a portable fluorescence sensor and spectroradiometer, respectively. Results showed that vegetation indices recorded at canopy level performed well for the early detection of slightly-diseased plants. The combined reflectance index, MCARI/TCARI, yielded the best discrimination between healthy and diseased plants across seven barley varieties. The blue to far-red fluorescence ratio (BFRR_UV and OSAVI were the best fluorescence and reflectance indices for estimating LCC, respectively, yielding R2 of 0.72 and 0.79. Partial least squares (PLS and support vector machines (SVM regression models further improved the use of fluorescence signals for the estimation of LCC, yielding R2 of 0.81 and 0.84, respectively. Our results demonstrate that non-destructive spectral measurements are able to detect mild disease symptoms before significant losses in LCC due to diseases under natural conditions.

  2. Leaf Level Chlorophyll Fluorescence Emission Spectra: Narrow Band versus Full 650-800 nm Retrievals

    Science.gov (United States)

    Middleton, E.; Zhang, Q.; Campbell, P. K.; Huemmrich, K. F.; Corp, L.; Cheng, Y.

    2012-12-01

    Recently, chlorophyll fluorescence (ChlF) retrievals in narrow spectral regions (sample the total full-spectrum ChlF and are made at non-optimal wavelengths since they are not located at the peak fluorescence emission features. We wish to estimate the total full-spectrum ChlF based on emissions obtained at selected wavelengths. For this, we drew upon leaf emission spectra measured on corn leaves obtained from a USDA experimental cornfield in MD (USA). These emission spectra were determined for the adaxial and abaxial (i.e., top and underside) surfaces of leaves measured throughout the 2008 and 2011 growing seasons (n>400) using a laboratory instrument (Fluorolog-3, Horiba Scientific, USA), recorded in either 1 nm or 5 nm increments with monochromatic excitation wavelengths of either 532 or 420 nm. The total ChlF signal was computed as the area under the continuous spectral emission curves, summing the emission intensities (counts per second) per waveband. The individual narrow (1 or 5 nm) waveband emission intensities were linearly related to full emission values, with variable success across the spectrum. Equations were developed to estimate total ChlF from these individual wavebands. Here, we report the results for the average adaxial/abaxial emissions. Very strong relationships were achieved for the relatively high fluorescence intensities at the red chlorophyll peak, centered at 685 nm (r2= 0.98, RMSE = 5.53 x 107 photons/s) and in the nearby O2-B atmospheric absorption feature centered at 688 nm (r2 = 0.94, RMSE = 4.04 x 107), as well as in the far-red peak centered at 740 nm (r2=0.94, RMSE = 5.98 x107). Very good retrieval success occurred for the O2-A atmospheric absorption feature on the declining NIR shoulder centered at 760 nm (r2 = 0.88, RMSE = 7.54 x 107). When perfect retrievals were assumed (0% noise), retrievals remained good in the low emission regions on either side of the peaks-- those associated with the H alpha line at 655 nm (r2 = 0.83, RMSE =8

  3. Chlorophyll induced fluorescence retrieved from GOME2 for improving gross primary productivity estimates of vegetation

    Science.gov (United States)

    van Leth, Thomas C.; Verstraeten, Willem W.; Sanders, Abram F. J.

    2014-05-01

    Mapping terrestrial chlorophyll fluorescence is a crucial activity to obtain information on the functional status of vegetation and to improve estimates of light-use efficiency (LUE) and global primary productivity (GPP). GPP quantifies carbon fixation by plant ecosystems and is therefore an important parameter for budgeting terrestrial carbon cycles. Satellite remote sensing offers an excellent tool for investigating GPP in a spatially explicit fashion across different scales of observation. The GPP estimates, however, still remain largely uncertain due to biotic and abiotic factors that influence plant production. Sun-induced fluorescence has the ability to enhance our knowledge on how environmentally induced changes affect the LUE. This can be linked to optical derived remote sensing parameters thereby reducing the uncertainty in GPP estimates. Satellite measurements provide a relatively new perspective on global sun-induced fluorescence, enabling us to quantify spatial distributions and changes over time. Techniques have recently been developed to retrieve fluorescence emissions from hyperspectral satellite measurements. We use data from the Global Ozone Monitoring Instrument 2 (GOME2) to infer terrestrial fluorescence. The spectral signatures of three basic components atmospheric: absorption, surface reflectance, and fluorescence radiance are separated using reference measurements of non-fluorescent surfaces (desserts, deep oceans and ice) to solve for the atmospheric absorption. An empirically based principal component analysis (PCA) approach is applied similar to that of Joiner et al. (2013, ACP). Here we show our first global maps of the GOME2 retrievals of chlorophyll fluorescence. First results indicate fluorescence distributions that are similar with that obtained by GOSAT and GOME2 as reported by Joiner et al. (2013, ACP), although we find slightly higher values. In view of optimizing the fluorescence retrieval, we will show the effect of the references

  4. Retrieval of aerosol parameters from the oxygen A band in the presence of chlorophyll fluorescence

    Directory of Open Access Journals (Sweden)

    A. F. J. Sanders

    2013-10-01

    Full Text Available We have investigated the precision of retrieved aerosol parameters for a generic aerosol retrieval algorithm over vegetated land using the O2 A band. Chlorophyll fluorescence is taken into account in the forward model. Fluorescence emissions are modeled as isotropic contributions to the upwelling radiance field at the surface and they are retrieved along with aerosol parameters. Precision is calculated by propagating measurement errors and a priori errors, including model parameter errors, using the forward model's derivatives. Measurement errors consist of noise and calibration errors. The model parameter errors considered are related to the single scattering albedo, surface pressure and temperature profile. We assume that measurement noise is dominated by shot noise; thus, results apply to grating spectrometers in particular. We describe precision for various atmospheric states, observation geometries and spectral resolutions of the instrument in a number of retrieval simulations. These precision levels can be compared with user requirements. A comparison of precision estimates with the literature and an analysis of the dependence on the a priori error in the fluorescence emission indicate that aerosol parameters can be retrieved in the presence of chlorophyll fluorescence: if fluorescence is present, fluorescence emissions should be included in the state vector to avoid biases in retrieved aerosol parameters.

  5. Retrieval of aerosol parameters from the oxygen A band in the presence of chlorophyll fluorescence

    Science.gov (United States)

    Sanders, A. F. J.; de Haan, J. F.

    2013-10-01

    We have investigated the precision of retrieved aerosol parameters for a generic aerosol retrieval algorithm over vegetated land using the O2 A band. Chlorophyll fluorescence is taken into account in the forward model. Fluorescence emissions are modeled as isotropic contributions to the upwelling radiance field at the surface and they are retrieved along with aerosol parameters. Precision is calculated by propagating measurement errors and a priori errors, including model parameter errors, using the forward model's derivatives. Measurement errors consist of noise and calibration errors. The model parameter errors considered are related to the single scattering albedo, surface pressure and temperature profile. We assume that measurement noise is dominated by shot noise; thus, results apply to grating spectrometers in particular. We describe precision for various atmospheric states, observation geometries and spectral resolutions of the instrument in a number of retrieval simulations. These precision levels can be compared with user requirements. A comparison of precision estimates with the literature and an analysis of the dependence on the a priori error in the fluorescence emission indicate that aerosol parameters can be retrieved in the presence of chlorophyll fluorescence: if fluorescence is present, fluorescence emissions should be included in the state vector to avoid biases in retrieved aerosol parameters.

  6. DIFFERENTIAL RESPONSES OF SEVEN CONTRASTING SPECIES TO HIGH LIGHT USING PIGMENT AND CHLOROPHYLL A FLUORESCENCE

    OpenAIRE

    Mittal S; Kumari, N.; Sharma, V.

    2011-01-01

    High light intensity may induce severe photodamage to chloroplast and consequently cause decreases in the yield capacity of plants and destruction of pigments, causing an overall yellowing of the foliage. Thus, study related to light adaptation becomes necessary to understand adaptation processes in higher plants on the basis of which they are characterized as full sunlight or shade plants. Chlorophyll can be regarded as an intrinsic fluorescent probe of the photosynthetic system. The ecophys...

  7. Chlorophyll fluorescence quenching as a tool to screen olive cultivars tolerant to drought stress

    OpenAIRE

    Faraloni, Cecilia; Cutino, Ilaria; Petruccelli, Raffaella; Leva, Anna Rita; Traversi, Maria Laura; Torzillo, Giuseppe

    2009-01-01

    The measurements of fluorescence chlorophyll is considered a promising technique to rapidly quantify the response to physiological stress in higher plants. Drought stress can be considered one of the most frequent environmental constraints causing the failure of newly planted trees. Olive tree (Olea europaea), a representative drought stress tolerant plant, is one of the most typical and economically relevant plant species grown in the Mediterranean area. However, as different cultivars may e...

  8. An Automated Comparative Observation System for Sun-Induced Chlorophyll Fluorescence of Vegetation Canopies

    OpenAIRE

    Xijia Zhou; Zhigang Liu; Shan Xu; Weiwei Zhang; Jun Wu

    2016-01-01

    Detecting sun-induced chlorophyll fluorescence (SIF) offers a new approach for remote sensing photosynthesis. However, to analyse the response characteristics of SIF under different stress states, a long-term time-series comparative observation of vegetation under different stress states must be carried out at the canopy scale, such that the similarities and differences in SIF change law can be summarized under different time scales. A continuous comparative observation system for vegetation ...

  9. Chlorophyll a Covalently Bonded to Organo-Modified Translucent Silica Xerogels: Optimizing Fluorescence and Maximum Loading

    Directory of Open Access Journals (Sweden)

    M. A. García-Sánchez

    2016-07-01

    Full Text Available Chlorophyll is a pyrrolic pigment with important optical properties, which is the reason it has been studied for many years. Recently, interest has been rising with respect to this molecule because of its outstanding physicochemical properties, particularly applicable to the design and development of luminescent materials, hybrid sensor systems, and photodynamic therapy devices for the treatment of cancer cells and bacteria. More recently, our research group has been finding evidence for the possibility of preserving these important properties of substrates containing chlorophyll covalently incorporated within solid pore matrices, such as SiO2, TiO2 or ZrO2 synthesized through the sol-gel process. In this work, we study the optical properties of silica xerogels organo-modified on their surface with allyl and phenyl groups and containing different concentrations of chlorophyll bonded to the pore walls, in order to optimize the fluorescence that these macrocyclic species displays in solution. The intention of this investigation was to determine the maximum chlorophyll a concentration at which this molecule can be trapped inside the pores of a given xerogel and to ascertain if this pigment remains trapped as a monomer, a dimer, or aggregate. Allyl and phenyl groups were deposited on the surface of xerogels in view of their important effects on the stability of the molecule, as well as over the fluorescence emission of chlorophyll; however, these organic groups allow the trapping of either chlorophyll a monomers or dimers. The determination of the above parameters allows finding the most adequate systems for subsequent in vitro or in vivo studies. The characterization of the obtained xerogels was performed through spectroscopic absorption, emission and excitation spectra. These hybrid systems can be employed as mimics of natural systems; the entrapment of chlorophyll inside pore matrices indicates that it is possible to exploit some of the most

  10. Chlorophyll a Covalently Bonded to Organo-Modified Translucent Silica Xerogels: Optimizing Fluorescence and Maximum Loading.

    Science.gov (United States)

    García-Sánchez, M A; Serratos, I N; Sosa, R; Tapia-Esquivel, T; González-García, F; Rojas-González, F; Tello-Solís, S R; Palacios-Enriquez, A Y; Esparza Schulz, J M; Arrieta, A

    2016-01-01

    Chlorophyll is a pyrrolic pigment with important optical properties, which is the reason it has been studied for many years. Recently, interest has been rising with respect to this molecule because of its outstanding physicochemical properties, particularly applicable to the design and development of luminescent materials, hybrid sensor systems, and photodynamic therapy devices for the treatment of cancer cells and bacteria. More recently, our research group has been finding evidence for the possibility of preserving these important properties of substrates containing chlorophyll covalently incorporated within solid pore matrices, such as SiO₂, TiO₂ or ZrO₂ synthesized through the sol-gel process. In this work, we study the optical properties of silica xerogels organo-modified on their surface with allyl and phenyl groups and containing different concentrations of chlorophyll bonded to the pore walls, in order to optimize the fluorescence that these macrocyclic species displays in solution. The intention of this investigation was to determine the maximum chlorophyll a concentration at which this molecule can be trapped inside the pores of a given xerogel and to ascertain if this pigment remains trapped as a monomer, a dimer, or aggregate. Allyl and phenyl groups were deposited on the surface of xerogels in view of their important effects on the stability of the molecule, as well as over the fluorescence emission of chlorophyll; however, these organic groups allow the trapping of either chlorophyll a monomers or dimers. The determination of the above parameters allows finding the most adequate systems for subsequent in vitro or in vivo studies. The characterization of the obtained xerogels was performed through spectroscopic absorption, emission and excitation spectra. These hybrid systems can be employed as mimics of natural systems; the entrapment of chlorophyll inside pore matrices indicates that it is possible to exploit some of the most physicochemical

  11. Detection of herbicide effects on pigment composition and PSII photochemistry in Helianthus annuus by Raman spectroscopy and chlorophyll a fluorescence.

    Science.gov (United States)

    Vítek, Petr; Novotná, Kateřina; Hodaňová, Petra; Rapantová, Barbora; Klem, Karel

    2017-01-01

    The effects of herbicides from three mode-of-action groups - inhibitors of protoporphyrinogen oxidase (carfentrazone-ethyl), inhibitors of carotenoid biosynthesis (mesotrione, clomazone, and diflufenican), and inhibitors of acetolactate synthase (amidosulfuron) - were studied in sunflower plants (Helianthus annuus). Raman spectroscopy, chlorophyll fluorescence (ChlF) imaging, and UV screening of ChlF were combined to evaluate changes in pigment composition, photosystem II (PSII) photochemistry, and non-photochemical quenching in plant leaves 6d after herbicide application. The Raman signals of phenolic compounds, carotenoids, and chlorophyll were evaluated and differences in their intensity ratios were observed. Strongly augmented relative content of phenolic compounds was observed in the case of amidosulfuron-treated plants, with a simultaneous decrease in the chlorophyll/carotenoid intensity ratio. The results were confirmed by in vivo measurement of flavonols using UV screening of ChlF. Herbicides from the group of carotenoid biosynthesis inhibitors significantly decreased both the maximum quantum efficiency of PSII and non-photochemical quenching as determined by ChlF. Resonance Raman imaging (mapping) data with high resolution (150,000-200,000 spectra) are presented, showing the distribution of carotenoids in H. annuus leaves treated by two of the herbicides acting as inhibitors of carotenoid biosynthesis (clomazone or diflufenican). Clear signs were observed that the treatment induced carotenoid depletion within sunflower leaves. The depletion spatial pattern registered differed depending on the type of herbicide applied.

  12. Effect of changes in chlorophyll concentration on photosynthetic properties I. Fluorescence and absorption of greening bean leaves

    NARCIS (Netherlands)

    Goedheer, J.C.

    1961-01-01

    In order to obtain new information about the way of functioning of chlorophyll in vivo a study was made of optical properties and photosynthesis under condition of a low chlorophyll content in the leave. It was found that the fluorescence yeild of greening bean leaves decreased from a value approxim

  13. 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 ...

  14. Effect of arsenic on reflectance spectra and chlorophyll fluorescence of aquatic plants.

    Science.gov (United States)

    Iriel, Analia; Dundas, Gavin; Fernández Cirelli, Alicia; Lagorio, Maria G

    2015-01-01

    Arsenic pollution of groundwater is a serious problem in many regions of Latin America that causes severe risks to human health. As a consequence, non-destructive monitoring methodologies, sensitive to arsenic presence in the environment and able to perform a rapid screening of large polluted areas, are highly sought-after. Both chlorophyll - a fluorescence and reflectance of aquatic plants may be potential indicators to sense toxicity in water media. In this work, the effects of arsenic on the optical and photophysical properties of leaves of different aquatic plants (Vallisneria gigantea, Azolla filiculoides and Lemna minor) were evaluated. Reflectance spectra were recorded for the plant leaves from 300 to 2400 nm. The spectral distribution of the fluorescence was also studied and corrected for light re-absorption processes. Photosynthetic parameters (Fv/Fm and ΦPSII) were additionally calculated from the variable chlorophyll fluorescence recorded with a pulse amplitude modulated fluorometer. Fluorescence and reflectance properties for V. gigantea and A. filiculoides were sensitive to arsenic presence in contrast to the behaviour of L. minor. Observed changes in fluorescence spectra could be interpreted in terms of preferential damage in photosystem II. The quantum efficiency of photosystem II for the first two species was also affected, decreasing upon arsenic treatment. As a result of this research, V. gigantea and A. filiculoides were proposed as bioindicators of arsenic occurrence in aquatic media. PMID:25150973

  15. Analysis of Red and Far-Red Sun-Induced Chlorophyll Fluorescence and Their Ratio in Different Canopies Based on Observed and Modeled Data

    Directory of Open Access Journals (Sweden)

    Micol Rossini

    2016-05-01

    Full Text Available Sun-induced canopy chlorophyll fluorescence in both the red (FR and far-red (FFR regions was estimated across a range of temporal scales and a range of species from different plant functional types using high resolution radiance spectra collected on the ground. Field measurements were collected with a state-of-the-art spectrometer setup and standardized methodology. Results showed that different plant species were characterized by different fluorescence magnitude. In general, the highest fluorescence emissions were measured in crops followed by broadleaf and then needleleaf species. Red fluorescence values were generally lower than those measured in the far-red region due to the reabsorption of FR by photosynthetic pigments within the canopy layers. Canopy chlorophyll fluorescence was related to plant photosynthetic capacity, but also varied according to leaf and canopy characteristics, such as leaf chlorophyll concentration and Leaf Area Index (LAI. Results gathered from field measurements were compared to radiative transfer model simulations with the Soil-Canopy Observation of Photochemistry and Energy fluxes (SCOPE model. Overall, simulation results confirmed a major contribution of leaf chlorophyll concentration and LAI to the fluorescence signal. However, some discrepancies between simulated and experimental data were found in broadleaf species. These discrepancies may be explained by uncertainties in individual species LAI estimation in mixed forests or by the effect of other model parameters and/or model representation errors. This is the first study showing sun-induced fluorescence experimental data on the variations in the two emission regions and providing quantitative information about the absolute magnitude of fluorescence emission from a range of vegetation types.

  16. Development of the spectrometric imaging apparatus of laser induced fluorescence from plants and estimation of chlorophyll contents of rice leaves; Laser reiki keiko sokutei sochi no kaihatsu to inehanai no chlorophyll ganryo no suitei

    Energy Technology Data Exchange (ETDEWEB)

    Nakaya, K.; Shoji, K.; Hanyu, H.

    1999-05-01

    Photosynthetic activity of plants is an important factor to assess the micrometeorological effect of plant canopy or to estimate the influence of circumstances such as water stress. Light illumination induces fluorescence from a leaf or suspension of chloroplasts. The red chlorophyll fluorescence had been used to determine the process of the electron transportation in photosynthetic reaction. The fluorescence source other than chlorophyll is not announced sufficiently, but is supposed to be useful to determine the contents of the substance corresponding to physiological response of plants. We developed a fluorescence imaging apparatus to observe spectrum and distribution of laser induced fluorescence from a leaf. Pulsed UV-laser (Nd:YAG) induced blue-green fluorescence and red chlorophyll fluorescence from a green leaf. The pulse modulated measuring light and CCD with image-intensifier (ICCD) enable to detect the fluorescence from plants under illumination. The laser induced fluorescence (LIF) spectra were investigated to estimate the chlorophyll contents in leaves of rice. During the greening course of dark grown etiolated rice leaves, chlorophyll contents were determined using the extraction of leaves and steady state LIF spectra were measured. As a result, the ratio of fluorescent intensity between blue-green and red peaks (F460/F740 and F510/F740) decreased in proportion to alteration of chlorophyll contents respectively. These fluorescence intensity ratios perform more precise estimation of higher chlorophyll contents of leaves than reported red chlorophyll fluorescence intensity ratio (F690/E740). (author)

  17. Rapid assessment of different oxygenic phototrophs and single-cell photosynthesis with multicolour variable chlorophyll fluorescence imaging

    DEFF Research Database (Denmark)

    Trampe, Erik Christian Løvbjerg; Kolbowski, J.; Schreiber, U.;

    2011-01-01

    We present a new system for microscopic multicolour variable chlorophyll fluorescence imaging of aquatic phototrophs. The system is compact and portable and enables microscopic imaging of photosynthetic performance of individual cells and chloroplasts using different combinations of blue, green...

  18. A Label-Free Microfluidic Biosensor for Activity Detection of Single Microalgae Cells Based on Chlorophyll Fluorescence

    Directory of Open Access Journals (Sweden)

    Junsheng Wang

    2013-11-01

    Full Text Available Detection of living microalgae cells is very important for ballast water treatment and analysis. Chlorophyll fluorescence is an indicator of photosynthetic activity and hence the living status of plant cells. In this paper, we developed a novel microfluidic biosensor system that can quickly and accurately detect the viability of single microalgae cells based on chlorophyll fluorescence. The system is composed of a laser diode as an excitation light source, a photodiode detector, a signal analysis circuit, and a microfluidic chip as a microalgae cell transportation platform. To demonstrate the utility of this system, six different living and dead algae samples (Karenia mikimotoi Hansen, Chlorella vulgaris, Nitzschia closterium, Platymonas subcordiformis, Pyramidomonas delicatula and Dunaliella salina were tested. The developed biosensor can distinguish clearly between the living microalgae cells and the dead microalgae cells. The smallest microalgae cells that can be detected by using this biosensor are 3 μm ones. Even smaller microalgae cells could be detected by increasing the excitation light power. The developed microfluidic biosensor has great potential for in situ ballast water analysis.

  19. A Graphical User Interface for Parameterizing Biochemical Models of Photosynthesis and Chlorophyll Fluorescence

    Science.gov (United States)

    Kornfeld, A.; Van der Tol, C.; Berry, J. A.

    2015-12-01

    Recent advances in optical remote sensing of photosynthesis offer great promise for estimating gross primary productivity (GPP) at leaf, canopy and even global scale. These methods -including solar-induced chlorophyll fluorescence (SIF) emission, fluorescence spectra, and hyperspectral features such as the red edge and the photochemical reflectance index (PRI) - can be used to greatly enhance the predictive power of global circulation models (GCMs) by providing better constraints on GPP. The way to use measured optical data to parameterize existing models such as SCOPE (Soil Canopy Observation, Photochemistry and Energy fluxes) is not trivial, however. We have therefore extended a biochemical model to include fluorescence and other parameters in a coupled treatment. To help parameterize the model, we then use nonlinear curve-fitting routines to determine the parameter set that enables model results to best fit leaf-level gas exchange and optical data measurements. To make the tool more accessible to all practitioners, we have further designed a graphical user interface (GUI) based front-end to allow researchers to analyze data with a minimum of effort while, at the same time, allowing them to change parameters interactively to visualize how variation in model parameters affect predicted outcomes such as photosynthetic rates, electron transport, and chlorophyll fluorescence. Here we discuss the tool and its effectiveness, using recently-gathered leaf-level data.

  20. Error in interpreting field chlorophyll fluorescence measurements: heat gain from solar radiation

    International Nuclear Information System (INIS)

    Temperature and chlorophyll fluorescence characteristics were determined on leaves of various horticultural species following a dark adaptation period where dark adaptation cuvettes were shielded from or exposed to solar radiation. In one study, temperature of Swietenia mahagoni (L.) Jacq. leaflets within cuvettes increased from approximately 36C to approximately 50C during a 30-minute exposure to solar radiation. Alternatively, when the leaflets and cuvettes were shielded from solar radiation, leaflet temperature declined to 33C in 10 to 15 minutes. In a second study, 16 horticultural species exhibited a lower variable: maximum fluorescence (Fv:Fm) when cuvettes were exposed to solar radiation during the 30-minute dark adaptation than when cuvettes were shielded. In a third study with S. mahagoni, the influence of self-shielding the cuvettes by wrapping them with white tape, white paper, or aluminum foil on temperature and fluorescence was compared to exposing or shielding the entire leaflet and cuvette. All of the shielding methods reduced leaflet temperature and increased the Fv:Fm ratio compared to leaving cuvettes exposed. These results indicate that heat stress from direct exposure to solar radiation is a potential source of error when interpreting chlorophyll fluorescence measurements on intact leaves. Methods for moderating or minimizing radiation interception during dark adaptation are recommended. (author)

  1. Remote Sensing of chlorophyll fluorescence and the impact of clouds on the retrival

    Science.gov (United States)

    Köhler, Philipp; Guanter, Luis; Frankenberg, Christian

    2013-04-01

    Remote sensing of sun-induced chlorophyll fluorescence (SIF) is a new, alternative option to gain information about terrestrial photosynthesis and CO2 assimilation on a global scale. The SIF is an electromagnetic signal emitted in the aprox. 650-800 nm spectral window by the photosynthesis apparatus, and can therefore be considered as a direct indicator of plant biochemical processes. The general approach to measure SIF from space is the evaluation of the in-filling of solar Fraunhofer lines or atmospheric absorption bands by SIF. To distinguish the SIF signal from the total incoming radiance at the sensor, which is about 100 times more intense, is a challenge and high resolution measurements are required. The high spectral resolution (approx. 0.02 nm) of the Fourier Transform Spectrometer (FTS) on-board the Greenhouse Gases Observing Satellite (GOSAT) enables such a measurement of SIF by means of the evaluation of the in-filling of solar Fraunhofer lines by SIF. The narrow wavelength band from 755 to 759 nm and around 770 nm can be used for this purpose because they are free from atmospheric absorption features, the solar radiation shows several Fraunhofer lines and the SIF values in this region are relatively high. A new SIF retrieval approach (GARLiC, for GOSAT Retrieval of cholorphyll fluorescence) will be presented in this contribution. This method is intended to simplify some of the assumptions of existing retrieval approaches without a loss in accuracy. The comparison of the GARLiC fluorescence retrievals with two state-of-the-art SIR retrieval methods such as those by Frankenberg et al. (2011) and Guanter et al. (2012) from GOSAT data shows corresponding and feasible results. In addition to the basics of SIF remote sensing, this contribution will assess the effect of clouds in the retrieval. To do this, the SIF retrieval has been coupled to a cloud optical thickness (COT) retrieval algorithm adapted to GOSAT-FTS O2A-band measurements, so that SIF and COT

  2. Use of O-J-I-P Chlorophyll Fluorescence Transients to Probe Multiple Effects of UV-C Radiation on the Photosynthetic Apparatus of Euglena

    Directory of Open Access Journals (Sweden)

    Chalinda Koshitha Beneragama

    2014-12-01

    Full Text Available Although the kinetic chlorophyll fluorescence signals are rich in information, most of the chlorophyll fluorescence related studies deal only with the quantum yield of primary photochemistry (Fv/Fm. JIP-test based OJIP fluorescence transient analysis is relatively a new technique to investigate the environmental stress responses of photosynthetic organisms. In the present study, the deleterious effects of ultraviolet (UV radiation on the photosynthetic machinery were probed by the JIP-test in Euglena, one of the most potent organisms for the future space stations. The cells were exposed to a series of UV-C doses and immediately after exposure, survival percentage was determined with Neutral Red staining, and the chlorophyll fluorescence was measured using AquaPen AP-C 100 fluorometer. Resultant OJIP transients were analyzed according to JIP-test, and several functional and structural parameters were derived to explain the PSII behavior. Results indicated that the UV-C induced inhibition of electron transport is severely affected due to higher sensitivity of dark reactions after QA -, represented as ψo, the electron transfer probability, than of the light dependent reactions, represented as φPo, the trapping probability. The performance index (PIABS of PSII, which is a combination of the indices of three independent parameters, decreased markedly in exponential manner in response to UVC. Results illustrate the advantage of using a number of fluorescent parameters over the use of one parameter, often the Fv/Fm.

  3. Dualex: A New Instrument for Field Measurements of Epidermal Ultraviolet Absorbance by Chlorophyll Fluorescence

    Science.gov (United States)

    Goulas, Yves; Cerovic, Zoran G.; Cartelat, Aurélie; Moya, Ismaël

    2004-08-01

    Dualex (dual excitation) is a field-portable instrument, hereby described, for the assessment of polyphenolic compounds in leaves from the measurement of UV absorbance of the leaf epidermis by double excitation of chlorophyll fluorescence. The instrument takes advantage of a feedback loop that equalizes the fluorescence level induced by a reference red light to the UV-light-induced fluorescence level. This allows quick measurement from attached leaves even under field conditions. The use of light-emitting diodes and of a leaf-clip configuration makes Dualex a user-friendly instrument with potential applications in ecophysiological research, light climate analysis, agriculture, forestry, horticulture, pest management, selection of medicinal plants, and wherever accumulation of leaf polyphenolics is involved in plant responses to the environment.

  4. Cytokinin-induced changes in the chlorophyll content and fluorescence of in vitro apple leaves.

    Science.gov (United States)

    Dobránszki, Judit; Mendler-Drienyovszki, Nóra

    2014-10-15

    Cytokinins (CKs) are one of the main regulators of in vitro growth and development and might affect the developmental state and function of the photosynthetic apparatus of in vitro shoots. Effects of different cytokinin regimes including different types of aromatic cytokinins, such as benzyl-adenine, benzyl-adenine riboside and 3-hydroxy-benzyladenine alone or in combination were studied on the capacity of the photosynthetic apparatus and the pigment content of in vitro apple leaves after 3 weeks of culture. We found that the type of cytokinins affected both chlorophyll a and b contents and its ratio. Chlorophyll content of in vitro apple leaves was the highest when benzyl-adenine was applied as a single source of cytokinin in the medium (1846-2176 μg/1g fresh weight (FW) of the leaf). Increasing the concentration of benzyl-adenine riboside significantly decreased the chlorophyll content of the leaves (from 1923 to 1183 μg/1g FW). The highest chl a/chl b ratio was detected after application of meta-topolin (TOP) at concentrations of 2.0 and 6.0 μM (2.706 and 2.804). Chlorophyll fluorescence was measured both in dark-adapted (Fv/Fm test) and in light-adapted leaf samples (Yield test; Y(II)). The maximum quantum yield and efficiency of leaves depended on the cytokinin source of the medium varied between 0.683 and 0.861 (Fv/Fm) indicating a well-developed and functional photosynthetic apparatus. Our results indicate that the type and concentration of aromatic cytokinins applied in the medium affect the chlorophyll content of the leaves in in vitro apple shoots. Performance of the photosynthetic apparatus measured by chlorophyll fluorescence in the leaves was also modified by the cytokinin supply. This is the first ever study on the relationship between the cytokinin supply and the functionability of photosystem II in plant tissue culture and our findings might help to increase plantlet survival after transfer to ex vitro conditions.

  5. An Automated Comparative Observation System for Sun-Induced Chlorophyll Fluorescence of Vegetation Canopies.

    Science.gov (United States)

    Zhou, Xijia; Liu, Zhigang; Xu, Shan; Zhang, Weiwei; Wu, Jun

    2016-01-01

    Detecting sun-induced chlorophyll fluorescence (SIF) offers a new approach for remote sensing photosynthesis. However, to analyse the response characteristics of SIF under different stress states, a long-term time-series comparative observation of vegetation under different stress states must be carried out at the canopy scale, such that the similarities and differences in SIF change law can be summarized under different time scales. A continuous comparative observation system for vegetation canopy SIF is designed in this study. The system, which is based on a high-resolution spectrometer and an optical multiplexer, can achieve comparative observation of multiple targets. To simultaneously measure the commonly used vegetation index and SIF in the O₂-A and O₂-B atmospheric absorption bands, the following parameters are used: a spectral range of 475.9 to 862.2 nm, a spectral resolution of approximately 0.9 nm, a spectral sampling interval of approximately 0.4 nm, and the signal-to-noise ratio (SNR) can be as high as 1000:1. To obtain data for both the upward radiance of the vegetation canopy and downward irradiance data with a high SNR in relatively short time intervals, the single-step integration time optimization algorithm is proposed. To optimize the extraction accuracy of SIF, the FluorMOD model is used to simulate sets of data according to the spectral resolution, spectral sampling interval and SNR of the spectrometer in this continuous observation system. These data sets are used to determine the best parameters of Fraunhofer Line Depth (FLD), Three FLD (3FLD) and the spectral fitting method (SFM), and 3FLD and SFM are confirmed to be suitable for extracting SIF from the spectral measurements. This system has been used to observe the SIF values in O₂-A and O₂-B absorption bands and some commonly used vegetation index from sweet potato and bare land, the result of which shows: (1) the daily variation trend of SIF value of sweet potato leaves is

  6. An Automated Comparative Observation System for Sun-Induced Chlorophyll Fluorescence of Vegetation Canopies

    Directory of Open Access Journals (Sweden)

    Xijia Zhou

    2016-05-01

    Full Text Available Detecting sun-induced chlorophyll fluorescence (SIF offers a new approach for remote sensing photosynthesis. However, to analyse the response characteristics of SIF under different stress states, a long-term time-series comparative observation of vegetation under different stress states must be carried out at the canopy scale, such that the similarities and differences in SIF change law can be summarized under different time scales. A continuous comparative observation system for vegetation canopy SIF is designed in this study. The system, which is based on a high-resolution spectrometer and an optical multiplexer, can achieve comparative observation of multiple targets. To simultaneously measure the commonly used vegetation index and SIF in the O2-A and O2-B atmospheric absorption bands, the following parameters are used: a spectral range of 475.9 to 862.2 nm, a spectral resolution of approximately 0.9 nm, a spectral sampling interval of approximately 0.4 nm, and the signal-to-noise ratio (SNR can be as high as 1000:1. To obtain data for both the upward radiance of the vegetation canopy and downward irradiance data with a high SNR in relatively short time intervals, the single-step integration time optimization algorithm is proposed. To optimize the extraction accuracy of SIF, the FluorMOD model is used to simulate sets of data according to the spectral resolution, spectral sampling interval and SNR of the spectrometer in this continuous observation system. These data sets are used to determine the best parameters of Fraunhofer Line Depth (FLD, Three FLD (3FLD and the spectral fitting method (SFM, and 3FLD and SFM are confirmed to be suitable for extracting SIF from the spectral measurements. This system has been used to observe the SIF values in O2-A and O2-B absorption bands and some commonly used vegetation index from sweet potato and bare land, the result of which shows: (1 the daily variation trend of SIF value of sweet potato leaves is

  7. Plant Chlorophyll Content Imager with Reference Detection Signals

    Science.gov (United States)

    Spiering, Bruce A. (Inventor); Carter, Gregory A. (Inventor)

    2000-01-01

    A portable plant chlorophyll imaging system is described which collects light reflected from a target plant and separates the collected light into two different wavelength bands. These wavelength bands, or channels, are described as having center wavelengths of 700 nm and 840 nm. The light collected in these two channels is processed using synchronized video cameras. A controller provided in the system compares the level of light of video images reflected from a target plant with a reference level of light from a source illuminating the plant. The percent of reflection in the two separate wavelength bands from a target plant are compared to provide a ratio video image which indicates a relative level of plant chlorophyll content and physiological stress. Multiple display modes are described for viewing the video images.

  8. Laser Induced Chlorophyll Fluorescence Spectra of Cajanus Cajan L Plant Growing Under Cadmium Stress

    Science.gov (United States)

    Gopal, Ram; Pandey, J. K.

    2010-06-01

    Laser-induced Chlorophyll fluorescence (LICF) spectra of Cajanus cajan L leaves treated with different concentrations of Cd (0.05, 0.5 and 1 mM) are recorded at 10 and 20 days after first treatment of cadmium. LICF spectra are recorded in the region of 650-780 nm using violet diode laser (405 nm). LICF spectra of plant leaves show two maxima near 685 and 730nm. Fluorescence induction kinetics (FIK) curve are recorded at 685 and 730 nm with red diode laser (635 nm) for excitation. The fluorescence intensity ratios (FIR) F685/F730 are calculated from LICF spectra and vitality index (Rfd) are determined from FIK curve. FIR and Rfd value are good stress indicator of plant health. These parameters along with chlorophyll content are used to analyze the effect of Cd on wheat plants. The result indicates that higher concentrations of Cd hazardous for photosynthetic activity and health of Arhar plants. The lower concentration of 0.05 mM shows stimulatory response up to 10 days while after 20 days this concentration also shows inhibitory response. R. Gopal, K. B. Mishra, M. Zeeshan, S. M. Prasad, and M. M. Joshi Curr. Sci., 83, 880, 2002 K. B. Mishra and R. Gopal Int. J. Rem. Sen., 29, 157, 2008 R. Maurya, S. M. Prasad, and R. Gopal J. Photochem. Photobio. C: Photochem. Rev., 9, 29, 2008

  9. Quantitative genetic analysis of chlorophyll a fluorescence parameters in maize in the field environments

    Institute of Scientific and Technical Information of China (English)

    Domagojimi; Hrvoje Lepedu; Vlatka Jurkovi; Jasenka Antunovi; Vera Cesar

    2014-01-01

    Chlorophyl fluorescence transient from initial to maximum fluorescence (“P”step) throughout two intermedi-ate steps (“J”and“I”) (JIP-test) is considered a reliable early quantitative indicator of stress in plants. The JIP-test is particularly useful for crop plants when applied in variable field environments. The aim of the present study was to conduct a quantitative trait loci (QTL) analysis for nine JIP-test parameters in maize during flowering in four field environ-ments differing in weather conditions. QTL analysis and identification of putative candidate genes might help to explain the genetic relationship between photosynthesis and different field scenarios in maize plants. The JIP-test param-eters were analyzed in the intermated B73 ? Mo17 (IBM) maize population of 205 recombinant inbred lines. A set of 2,178 molecular markers across the whole maize genome was used for QTL analysis revealing 10 significant QTLs for seven JIP-test parameters, of which five were co-localized when combined over the four environments indicating polygenic inheritance and pleiotropy. Our results demonstrate that QTL analysis of chlorophyl fluorescence parameters was capable of detecting one pleiotropic locus on chromosome 7, coinciding with the gene gst23 that may be associated with efficient photosynthe-sis under different field scenarios.

  10. Phenotyping of wheat cultivars for heat tolerance using chlorophyll a fluorescence

    DEFF Research Database (Denmark)

    Sharma, Dew Kumari; Andersen, Sven Bode; Ottosen, Carl-Otto;

    2012-01-01

    on a physiological trait, the maximum quantum efficiency of PSII (Fv/Fm). A chlorophyll fluorescence protocol was standardised and used for repeated screening with increased selection pressure with a view to identifying a set of cultivars extreme for the trait. An initial mass screening of 1274 wheat cultivars....... The identification of a set of wheat cultivars contrasting for their inherent photochemical efficiency may aid future studies to understand the genetic and physiological nature of heat stress tolerance in order to dissect quantitative traits into simpler genetic factors....

  11. Relationship between the Fluorescence Lifetime of Chlorophyll 'a' and Primary Productivity within the Mississippi River Plume and Adjacent Shelf Region

    Science.gov (United States)

    Hall, Callie; Miller, Richard L.; Fernandez, Salvador M.; McKee, Brent A.

    2000-01-01

    In situ measurements of chlorophyll fluorescence intensity have been widely used to estimate phytoplankton biomass. However, because the fluorescence quantum yield of chlorophyll a in vivo can be highly variable, measurements of chlorophyll fluorescence intensity cannot be directly correlated with phytoplankton biomass and do not provide information on the physiological state of the phytoplankton under study. Conversely, lifetime-based measurements of chlorophyll fluorescence provide a framework in which photosynthetic rates of phytoplankton can be analyzed according to phytoplankton physiology. Along with the measurement of primary production and ambient nutrient concentrations within the Mississippi River plume in the northern Gulf of Mexico, phytoplankton fluorescence lifetimes were measured using a Fluorescence Lifetime Phytoplankton Analyzer (developed under a NASA Small Business Innovative Research contract to Ciencia, Inc.). Variability of fluorescence lifetimes within the plume can be used as a background from which to interpret variations in the maximum quantum yield of photochemistry. The extent to which nutrient and effluent loading in this dynamic coastal area affect the photosynthetic performance of phytoplankton will be presented as a function of phytoplankton fluorescence lifetimes.

  12. Violet diode laser-induced chlorophyll fluorescence: a tool for assessing mosaic disease severity in cassava (Manihot esculenta Crantz) cultivars.

    Science.gov (United States)

    Anderson, Benjamin; Eghan, Moses J; Asare-Bediako, Elvis; Buah-Bassuah, Paul K

    2012-01-01

    Violet diode laser-induced chlorophyll fluorescence was used in agronomical assessment (disease severity and average yield per plant). Because cassava (Manihot esculenta Crantz) is of economic importance, improved cultivars with various levels of affinity for cassava mosaic disease were investigated. Fluorescence data correlated with cassava mosaic disease severity levels and with the average yield per plant.

  13. A Dioxobilin-Type Fluorescent Chlorophyll Catabolite as a Transient Early Intermediate of the Dioxobilin-Branch of Chlorophyll Breakdown in Arabidopsis thaliana.

    Science.gov (United States)

    Süssenbacher, Iris; Hörtensteiner, Stefan; Kräutler, Bernhard

    2015-11-01

    Chlorophyll breakdown in higher plants occurs by the so called "PaO/phyllobilin" path. It generates two major types of phyllobilins, the characteristic 1-formyl-19-oxobilins and the more recently discovered 1,19-dioxobilins. The hypothetical branching point at which the original 1-formyl-19-oxobilins are transformed into 1,19-dioxobilins is still elusive. Here, we clarify this hypothetical crucial transition on the basis of the identification of the first natural 1,19-dioxobilin-type fluorescent chlorophyll catabolite (DFCC). This transient chlorophyll breakdown intermediate was isolated from leaf extracts of Arabidopsis thaliana at an early stage of senescence. The fleetingly existent DFCC was then shown to represent the direct precursor of the major nonfluorescent 1,19-dioxobilin that accumulated in fully senescent leaves.

  14. Evaluation of Chlorophyll Content and Fluorescence Parameters as Indicators of Drought Tolerance in Barley

    Institute of Scientific and Technical Information of China (English)

    LI Rong-hua; GUO Pei-guo; Michael Baum; Stefania Grando; Salvatore Ceccarelli

    2006-01-01

    Drought is a major abiotic stress that severely affects food production worldwide. Agronomic and physiological traits associated with drought tolerance are suitable indicators for selection of drought tolerance genotypes to reduce the impact of water deficit on crop yield in breeding program. The objective of this study was to identify indicators related to drought tolerance through analysis of photosynthetic traits in barley (Hordeum vulgare L.). These traits included chlorophyll content, initial fluorescence (Fo), maximum primary yield of photochemistry of pho tosystem Ⅱ (Fv / Fo) and maximum quantum yield of photosystem Ⅱ (Fv/Fm). Four genotypes (Tadmor, Arta, Morocco9-75 and WI2291) variable in drought tolerance were used to investigate the correlation between these traits and drought tolerance. The results reflected that all of these traits were affected negatively in the four genotypes at different levels of post-anthesis drought stress, but the decrease in drought tolerant genotypes was much less than that of drought sensitive genotypes. The results further revealed that the components of the photosynthetic apparatus could be damaged significantly in drought sensitive genotypes, while drought tolerant genotypes were relatively less affected. On the other hand, the values of chlorophyll content, Fo, Fv/Fo and Fv/Fm in drought tolerance genotypes were significantly higher than those in drought sensitive genotypes under drought stress. It was concluded that chlorophyll content, Fo, Fv / Fo and Fv / Fm could be considered as reliable indicators in screening barley germplasm for drought tolerance.

  15. Field experiments of multi-channel oceanographic fluorescence lidar for oil spill and chlorophyll- a detection

    Science.gov (United States)

    Li, Xiaolong; Zhao, Chaofang; Ma, Youjun; Liu, Zhishen

    2014-08-01

    A Multi-channel Oceanographic Fluorescence Lidar (MOFL), with a UV excitation at 355 nm and multiple receiving channels at typical wavelengths of fluorescence from oil spills and chlorophyll- a (Chl- a), has been developed using the Laser-induced Fluorescence (LIF) technique. The sketch of the MOFL system equipped with a compact multi-channel photomultiplier tube (MPMT) is introduced in the paper. The methods of differentiating the oil fluorescence from the background water fluorescence and evaluating the Chl- a concentration are described. Two field experiments were carried out to investigate the field performance of the system, i.e., an experiment in coastal areas for oil pollution detection and an experiment over the Yellow Sea for Chl- a monitoring. In the coastal experiment, several oil samples and other fluorescence substances were used to analyze the fluorescence spectral characteristics for oil identification, and to estimate the thickness of oil films at the water surface. The experiment shows that both the spectral shape of fluorescence induced from surface water and the intensity ratio of two channels ( I 495/ I 405) are essential to determine oil-spill occurrence. In the airborne experiment, MOFL was applied to measure relative Chl- a concentrations in the upper layer of the ocean. A comparison of relative Chl- a concentration measurements by MOFL and the Moderate Resolution Imaging Spectroradiometer (MODIS) indicates that the two datasets are in good agreement. The results show that the MOFL system is capable of monitoring oil spills and Chl- a in the upper layer of ocean water.

  16. Effect of carbon and nitrogen assimilation on chlorophyll fluorescence emission by the cyanobacterium Anacystis nidulans

    Energy Technology Data Exchange (ETDEWEB)

    Romero, J.M.; Lara, C. (Instituto de Bioquimica Vegetal y Fotosintesis, Univ. de Sevilla y CSIC, Sevilla (ES)); Sivak, M.N. (Dept. of Biochemistry, Michigan State Univ., East Lansing (US))

    1992-01-01

    O{sub 2} evolution and chlorophyll A fluorescence emission have been monitored in intact cells of the cyanobacterium Anacystis nidulans 1402-1 to study the influence of carbon and nitrogen assimilation on the operation of the photosynthetic apparatus. The pattern of fluorescence induction in dark-adapted cyanobacterial cells was different from that of higher plants. Cyanobacteria undergo large, rapid state transitions upon illumination, which lead to marked changes in the fluorescence yield, complicating the estimation of quenching coefficients. The Kautsky effect was not evident, although it could be masked by a state II-state I transition, upon illumination with actinic light. The use of inhibitors of carbon assimilation such as D,L-glyceraldehyde or iodoacetamide allowed us to relate changes in variable fluorescence to active CO{sub 2} fixation. Ammonium, but not nitrate, induced non-photochemical fluorescence quenching, in agreement with a previous report on green algae, indicative of an ammonium-induced state i transition. (au).

  17. Evaluation of Copper Oxide Nanoparticles Toxicity Using Chlorophyll a Fluorescence Imaging in Lemna gibba

    Directory of Open Access Journals (Sweden)

    François Perreault

    2010-01-01

    Full Text Available Copper oxide nanoparticles (CuO NPs, used in antifouling paints of boats, are released in the environment and can induce toxicity to aquatic organisms. In this report, we used chlorophyll a fluorescence imaging to evaluate CuO NPs toxicity in Lemna gibba. This approach allowed to evaluate the differential effect of CuO NPs on photosynthesis of whole L. gibba plants. Exposure to 0.1 to 0.4 g/L CuO NPs during 48h induced strong inhibition of photosynthetic processes resulting in a decrease of plant growth. By using fluorescence imaging, different photosynthetic parameters were evaluated simultaneously in microplate conditions. Imaging of FO fluorescence yield showed the decrease of leaf photosynthetic active surface for whole plants exposed to CuO NPs. This method showed that CuO NPs inhibited photosystem II maximal, photosystem II operational quantum yields, and photochemical quenching of fluorescence associated with electron transport. Nonphotochemical fluorescence quenching as an indicator of energy dissipation not used in photosynthesis was shown to be increased by the effect of CuO NPs. Such approach in microplate conditions provides synchronous high repetition measurements for numerous plants. This study may give a reliable methodological approach to evaluate toxicity risk of NPs in aquatic ecosystems.

  18. Chlorophyll Fluorescence as a Tool to Assess the Regeneration Potential of African Violet Leaf Explants

    Directory of Open Access Journals (Sweden)

    Norbert KEUTGEN

    2016-06-01

    Full Text Available Micropropagation of many ornamentals has enabled their efficient commercialisation and many problems have been solved by the elaboration of adequate culture protocols. Nevertheless, a non-destructive technique for monitoring the developmental progress of explants would be desirable. The present study focussed on the applicability of chlorophyll fluorescence in leaf explants of African violet (a Saintpaulia ionantha × confusa – hybrid explanted onto Murashige and Skoog basic medium. The explants that survived on the medium without additional phytohormones had the capacity to develop further into two different kinds of explants: light green explants, characterized by a non-regular size growth and stiffer appearance, and dark green explants capable of organogenesis. Compared to the source leaves of African violet plants, explants were characterized by reduced chlorophyll (Chl and carotenoid (Car contents as well as a tendency towards a higher Car/Chl ratio. The Chl a/b ratio decreased significantly in the light green explants. A reduction of maximum quantum efficiency of photosystem II (Fv/Fm accompanied by a high percentage (> 50% of thermal energy dissipation as a consequence of an elevated light intensity (800 µmol m-2 s-1 quanta indicated photoinhibition in the light green explants, whereas in the dark green explants the largest percentage (> 50% of the light energy was dissipated into the fraction of photon energy trapped by ‘closed’ photosystem II reaction centres. These results suggest that the capacity of organogenesis of leaf explants of African violet can be monitored using chlorophyll fluorescence, because it is related to modifications of the photosynthetic system.

  19. Changes in Chlorophyll Fluorescence of Rice Mutants Induced by High Hydrostatic Pressure

    Institute of Scientific and Technical Information of China (English)

    BAI Cheng-ke; LI Gui-shuang; PENG Chang-lian; DUAN Jun

    2003-01-01

    Three mutants of rice (Oryza sativa L. ), Mutant 1, Mutant 2and Mutant 3, which were selected by high hydrostatic pressure (75 MPa), and their parent Yuexiangzhan were used to study the changes in chlorophyll fluorescence during different growth stages. In all the three mutants, the function of PSⅡ was improved, Fy/Fm ratio of mutants increased compared to their parent at tillering and heading stage, and φPS Ⅱ also improved except for Mutant 2 at heading stage. Similar to their parent, the mutants exhibited slight photoinhibition at noon and almost complete recovery to initial levels of 6:00 after 18:00 at heading stage. At milking stage, the photoinhibition in the mutants was obvious, and recovered rapidly compared to the parent. Yields of individual plant and grain/straw ratio were also higher in three mutants than the parent. Results indicated that characteristics of chlorophyll fluorescence in leaves of mutants and their photoinhibition in the field had changed. It is suggested that high hydrostatic pressure induction could be applied as a new effective approach in high-yield rice breeding in the future.

  20. Interactions between iron and titanium metabolism in spinach: a chlorophyll fluorescence study in hydropony.

    Science.gov (United States)

    Cigler, Petr; Olejnickova, Julie; Hruby, Martin; Csefalvay, Ladislav; Peterka, Jiri; Kuzel, Stanislav

    2010-12-15

    One of the elements showing strong beneficial effect on plants at low concentrations and toxic effects at higher concentrations is titanium (Ti). We investigated the interconnection between the Fe uptake and the Ti intoxication in model experiment on Fe-deficient spinach (Spinacia oleracea) plants to help to elucidate the mechanism of the biological activity of titanium in plants. The two different Ti (0 and 20 mg L⁻¹) and two different Fe (0 and 1.35 mg L⁻¹) concentrations in hydroponic medium were used in all four possible combinations. We compared chemical analysis of Ti and Fe in roots and shoots with the changes of the in vivo chlorophyll fluorescence. Although Fe and Ti concentration found in shoots of Ti-non-treated Fe-deficient plants was comparable with that in Ti-treated Fe-deficient plants, the soluble form of Ti present in the growth media had a negative effect on photosynthetic activity monitored by chlorophyll fluorescence measurements. The presence of Fe in growth medium significantly decreased the Ti concentration in shoots and increased the photosynthetic activity. Here, we propose that Ti affect components of electron transport chain containing Fe in their structure (particularly photosystem I) and decrease the photosystem II efficiency. PMID:20708819

  1. Chlorophyll Fluorescence Emissions of Vegetation Canopies From High Resolution Field Reflectance Spectra

    Science.gov (United States)

    Middleton, E. M.; Corp, L. A.; Daughtry, C. S. T.; Campbell, P. K. Entcheva

    2006-01-01

    A two-year experiment was performed on corn (Zea mays L.) crops under nitrogen (N) fertilization regimes to examine the use of hyperspectral canopy reflectance information for estimating chlorophyll fluorescence (ChlF) and vegetation production. Fluorescence of foliage in the laboratory has proven more rigorous than reflectance for correlation to plant physiology. Especially useful are emissions produced from two stable red and far-red chlorophyll ChlF peaks centered at 685V10 nm and 735V5 nm. Methods have been developed elsewhere to extract steady state solar induced fluorescence (SF) from apparent reflectance of vegetation canopies/landscapes using the Fraunhofer Line Depth (FLD) principal. Our study utilized these methods in conjunction with field-acquired high spectral resolution canopy reflectance spectra obtained in 2004 and 2005 over corn crops, as part of an ongoing multi-year experiment at the USDA/Agriculture Research Service in Beltsville, MD. A spectroradiometer (ASD-FR Fieldspec Pro, Analytical Spectral Devices, Inc., Boulder, CO) was used to measure canopy radiances 1 m above plant canopies with a 22deg field of view and a 0deg nadir view zenith angle. Canopy and plant measurements were made at the R3 grain fill reproductive stage on 3-4 replicate N application plots provided seasonal inputs of 280, 140, 70, and 28 kg N/ha. Leaf level measurements were also made which included ChlF, photosynthesis, and leaf constituents (photosynthetic pigment, carbon (C), and N contents). Crop yields were determined at harvest. SIF intensities for ChlF were derived directly from canopy reflectance spectra in specific narrowband regions associated with atmospheric oxygen absorption features centered at 688 and 760 nm. The red/far-red S F ratio derived from these field reflectance spectra successfully discriminated foliar pigment levels (e.g., total chlorophyll, Chl) associated with N application rates in both corn crops. This canopy-level spectral ratio was also

  2. A Method for Chlorophyll Fluorescence Imaging Control of the Vegetation under Microgravity Conditions

    Science.gov (United States)

    Krumov, A.; Vassilev, V.; Vassilev, N.

    term space exploration and flights. The goal is to provide a more natural environment on physiological, psychological and even esthetical levels for the astronauts. One of the important issues to be solved is development of methodologies and apparatus for continuous in-flight monitoring the biophysical status of the vegetation in order to assure it within the required physiological conditions. performed in the last years. There, applying qualitative observations and/or measurement of certain physiological parameters on different vegetation samples, the monitoring of the plant biostatus is done. These samples are prepared and characterized directly on board of the spacecraft, or are sent back to Earth, usually in a dried condition, for further investigation. In such a way, it is not possible to have a quick, real time control of the dynamics of the vegetation bioprocesses. When sudden plant stress condition appears, this can lead to a delayed and improper intervention by the operator and to irreversible changes in the physiological functions of the vegetation. A very promising approach for controlling the vegetation physiological processes and early detection of stress conditions is using the light induced chlorophyll fluorescence as an indicator for the plant biostatus. the registration of the intensity and the spatial distribution of the chlorophyll fluorescence, induced by a discrete spectrum light flux. The use of discontinuous spectrum is implied by the fact that the fluorescence irradiated by the vegetation is of much lower intensity than the one of the incident light. When the incident flux has a wide continuos spectrum, including the spectral bands of florescence, the latter is difficult to detect directly. We suggest to measure the fluorescence in bands of approximately 10nm width, centered at the maximum intensity fluorescence wave lengths, in which the spectrum of the incident light to be discontinued. These maxima of fluorescence are at 440nm and 520nm

  3. Temporal variability in chlorophyll fluorescence of back-reef corals in Ofu, American Samoa

    Science.gov (United States)

    Piniak, G.A.; Brown, E.K.

    2009-01-01

    Change in the yield of chlorophyll a fluorescence is a common indicator of thermal stress in corals. The present study reports temporal variability in quantum yield measurements for 10 coral species in Ofu, American Samoa - a place known to experience elevated and variable seawater temperatures. In winter, the zooxanthellae generally had higher dark-adapted maximum quantum yield (F v/Fm), higher light- adapted effective quantum yield (??F/F'm), and lower relative electron transport rates (rETR) than in the summer. Temporal changes appeared unrelated to the expected bleaching sensitivity of corals. All species surveyed, with the exception of Montipora grisea, demonstrated significant temporal changes in the three fluorescence parameters. Fluorescence responses were influenced by the microhabitat - temporal differences in fluorescence parameters were usually observed in the habitat with a more variable temperature regime (pool 300), while differences in Fv/Fm between species were observed only in the more environmentally stable habitat (pool 400). Such species-specific responses and microhabitat variability should be considered when attempting to determine whether observed in situ changes are normal seasonal changes or early signs of bleaching. ?? 2009 Marine Biological Laboratory.

  4. Leaf Gas Exchange and Chlorophyll a Fluorescence Imaging of Rice Leaves Infected with Monographella albescens.

    Science.gov (United States)

    Tatagiba, Sandro Dan; DaMatta, Fábio Murilo; Rodrigues, Fabrício Ávila

    2015-02-01

    This study was intended to analyze the photosynthetic performance of rice leaf blades infected with Monographella albescens by combining chlorophyll (Chl) a fluorescence images with gas exchange and photosynthetic pigment pools. The net CO2 assimilation rate, stomatal conductance, transpiration rate, total Chl and carotenoid pools, and Chl a/b ratio all decreased but the internal CO2 concentration increased in the inoculated plants compared with their noninoculated counterparts. The first detectable changes in the images of Chl a fluorescence from the leaves of inoculated plants were already evident at 24 h after inoculation (hai) and increased dramatically as the leaf scald lesions expanded. However, these changes were negligible for the photosystem II photochemical efficiency (Fv/Fm) at 24 hai, in contrast to other Chl fluorescence traits such as the photochemical quenching coefficient, yield of photochemistry, and yield for dissipation by downregulation; which, therefore, were much more sensitive than the Fv/Fm ratio in assessing the early stages of fungal infection. It was also demonstrated that M. albescens was able to impair the photosynthetic process in both symptomatic and asymptomatic leaf areas. Overall, it was proven that Chl a fluorescence imaging is an excellent tool to describe the loss of functionality of the photosynthetic apparatus occurring in rice leaves upon infection by M. albescens.

  5. Use of in vivo chlorophyll fluorescence to estimate photosynthetic activity and biomass productivity in microalgae grown in different culture systems

    Directory of Open Access Journals (Sweden)

    Félix L Figueroa

    2013-11-01

    Full Text Available In vivo chlorophyll fluorescence associated to Photosystem II is being used to evaluate photosynthetic activity of microalgae grown in different types of photobioreactors; however, controversy on methodology is usual. Several recommendations on the use of chlorophyll fluorescence to estimate electron transport rate and productivity of microalgae grown in thin-layer cascade cultivators and methacrylate cylindrical vessels are included. Different methodologies related to the measure of photosynthetic activity in microalgae are discussed: (1 measurement of light absorption, (2 determination of electron transport rates versus irradiance and (3 use of simplified devices based on pulse amplitude modulated (PAM fluorescence as Junior PAM or Pocket PAM with optical fiber and optical head as measuring units, respectively. Data comparisons of in vivo chlorophyll fluorescence by using these devices and other PAM fluorometers as Water-PAM in the microalga Chlorella sp. (Chlorophyta are presented. Estimations of carbon production and productivity by transforming electron transport rate to gross photosynthetic rate (as oxygen evolution using reported oxygen produced per photons absorbed values and carbon photosynthetic yield based on reported oxygen/carbon ratio are also shown. The limitation of ETR as estimator of photosynthetic and biomass productivity is discussed. Low cost:quality PAMs can promote monitoring of chlorophyll fluorescence in algal biotechnology to estimate the photosynthetic activity and biomass productivity.

  6. Relationship between leaf optical properties, chlorophyll fluorescence and pigment changes in senescing Acer saccharum leaves.

    Science.gov (United States)

    Junker, Laura Verena; Ensminger, Ingo

    2016-06-01

    The ability of plants to sequester carbon is highly variable over the course of the year and reflects seasonal variation in photosynthetic efficiency. This seasonal variation is most prominent during autumn, when leaves of deciduous tree species such as sugar maple (Acer saccharum Marsh.) undergo senescence, which is associated with downregulation of photosynthesis and a change of leaf color. The remote sensing of leaf color by spectral reflectance measurements and digital repeat images is increasingly used to improve models of growing season length and seasonal variation in carbon sequestration. Vegetation indices derived from spectral reflectance measurements and digital repeat images might not adequately reflect photosynthetic efficiency of red-senescing tree species during autumn due to the changes in foliar pigment content associated with autumn phenology. In this study, we aimed to assess how effectively several widely used vegetation indices capture autumn phenology and reflect the changes in physiology and photosynthetic pigments during autumn. Chlorophyll fluorescence and pigment content of green, yellow, orange and red leaves were measured to represent leaf senescence during autumn and used as a reference to validate and compare vegetation indices derived from leaf-level spectral reflectance measurements and color analysis of digital images. Vegetation indices varied in their suitability to track the decrease of photosynthetic efficiency and chlorophyll content despite increasing anthocyanin content. Commonly used spectral reflectance indices such as the normalized difference vegetation index and photochemical reflectance index showed major constraints arising from a limited representation of gradual decreases in chlorophyll content and an influence of high foliar anthocyanin levels. The excess green index and green-red vegetation index were more suitable to assess the process of senescence. Similarly, digital image analysis revealed that vegetation

  7. High-light stress and photoprotection in Umbilicaria antarctica monitored by chlorophyll fluorescence imaging and changes in zeaxanthin and glutathione.

    Science.gov (United States)

    Barták, M; Hájek, J; Vráblíková, H; Dubová, J

    2004-05-01

    The effect of high light on spatial distribution of chlorophyll (Chl) fluorescence parameters over a lichen thallus (Umbilicaria antarctica) was investigated by imaging of Chl fluorescence parameters before and after exposure to high light (1500 micro mol m (-2) s (-1), 30 min at 5 degrees C). False colour images of F (V)/F (M) and Phi (II) distribution, taken over thallus with 0.1 mm (2) resolution, showed that maximum F (V)/F (M) and Phi (II) values were located close to the thallus centre. Minimum values were typical for thallus margins. After exposure to high light, a differential response of F (V)/F (M) and Phi (II) was found. The marginal thallus part exhibited a loss of photosynthetic activity, manifested as a lack of Chl fluorescence signal, and close-to-centre parts showed a different extent of F (V)/F (M) and Phi (II) decrease. Subsequent recovery in the dark led to a gradual return of F (V)/F (M) and Phi (II) to their initial values. Fast (30 min) and slow (1 - 22 h) phase of recovery were distinguished, suggesting a sufficient capacity of photoprotective mechanisms in U. antarctica to cope with low-temperature photoinhibition. Glutathione and xanthophyll cycle pigments were analyzed by HPLC. High light led to an increase in oxidized glutathione (GSSG), and a conversion of violaxanthin to zeaxanthin, expressed as their de-epoxidation state (DEPS). The responses of GSSG and DEPS were reversible during subsequent recovery in the dark. GSSG and DEPS were highly correlated to non-photochemical quenching (NPQ), indicating involvement of these antioxidants in the resistance of U. antarctica to high-light stress. Heterogeneity of Chl fluorescence parameters over the thallus and differential response to high light are discussed in relation to thallus anatomy and intrathalline distribution of the symbiotic alga Trebouxia sp. PMID:15143442

  8. [Flag leaf photosynthetic characteristics, change in chlorophyll fluorescence parameters, and their relationships with yield of winter wheat sowed in spring].

    Science.gov (United States)

    Xu, Lan; Gao, Zhi-qang; An, Wei; Li, Yan-liang; Jiao, Xiong-fei; Wang, Chuang-yun

    2016-01-01

    With five good winter wheat cultivars selected from the middle and lower reaches of Yangtze River and Southwest China as test materials, a field experiment in Xinding basin area of Shanxi Province was conducted to study the photosynthetic characteristics, chlorophyll content, and chlorophyll fluorescence parameters of flag leaf at different sowing dates, as well as the correlations between these indices and yield for two years (2013-2014). The results showed that the difference in most fluorescence parameters except chlorophyll content among cultivars was significant. The correlations between these fluorescence parameters and yield were significant. The variation coefficient of chlorophyll (Chl) content was low (0.12-0.17), and that of performance index based on absorption (PIabs) was high (0.32-0.39), with the partial correlation coefficients of them with grain yield from 2013 to 2014 ranged in 0.70-0.81. Under the early sowing condition, the grain yield positively correlated with PIabs at flowering and filling stages and chlorophyll content at grain filling stage, but negatively correlated with the relative variable fluorescence at I point (Vi) at grain filling stage. About 81.1%-82.8% of grain yield were determined by the variations of PIabs, Chl, and Vi. Wheat cultivars had various performances in the treatments with different sowing dates and a consistent trend was observed in the two experimental years. Among these 5 cultivars, Yangmai 13 was suitable for early sowing, with the flag leaf photosynthetic rate (Pn), Chl, most fluorescence parame-ters, and grain yield showed obviously high levels. In conclusion, under early sowing condition chlorophyll content at grain filling stages, PIabs at flowering and filling stages, and Pn were important indices for selecting wheat cultivars with high photosynthetic efficiency. PMID:27228602

  9. [Flag leaf photosynthetic characteristics, change in chlorophyll fluorescence parameters, and their relationships with yield of winter wheat sowed in spring].

    Science.gov (United States)

    Xu, Lan; Gao, Zhi-qang; An, Wei; Li, Yan-liang; Jiao, Xiong-fei; Wang, Chuang-yun

    2016-01-01

    With five good winter wheat cultivars selected from the middle and lower reaches of Yangtze River and Southwest China as test materials, a field experiment in Xinding basin area of Shanxi Province was conducted to study the photosynthetic characteristics, chlorophyll content, and chlorophyll fluorescence parameters of flag leaf at different sowing dates, as well as the correlations between these indices and yield for two years (2013-2014). The results showed that the difference in most fluorescence parameters except chlorophyll content among cultivars was significant. The correlations between these fluorescence parameters and yield were significant. The variation coefficient of chlorophyll (Chl) content was low (0.12-0.17), and that of performance index based on absorption (PIabs) was high (0.32-0.39), with the partial correlation coefficients of them with grain yield from 2013 to 2014 ranged in 0.70-0.81. Under the early sowing condition, the grain yield positively correlated with PIabs at flowering and filling stages and chlorophyll content at grain filling stage, but negatively correlated with the relative variable fluorescence at I point (Vi) at grain filling stage. About 81.1%-82.8% of grain yield were determined by the variations of PIabs, Chl, and Vi. Wheat cultivars had various performances in the treatments with different sowing dates and a consistent trend was observed in the two experimental years. Among these 5 cultivars, Yangmai 13 was suitable for early sowing, with the flag leaf photosynthetic rate (Pn), Chl, most fluorescence parame-ters, and grain yield showed obviously high levels. In conclusion, under early sowing condition chlorophyll content at grain filling stages, PIabs at flowering and filling stages, and Pn were important indices for selecting wheat cultivars with high photosynthetic efficiency.

  10. [Remote sensing of chlorophyll fluorescence at airborne level based on unmanned airship platform and hyperspectral sensor].

    Science.gov (United States)

    Yang, Pei-Qi; Liu, Zhi-Gang; Ni, Zhuo-Ya; Wang, Ran; Wang, Qing-Shan

    2013-11-01

    The solar-induced chlorophyll fluorescence (ChlF) has a close relationship with photosynthetic and is considered as a probe of plant photosynthetic activity. In this study, an airborne fluorescence detecting system was constructed by using a hyperspectral imager on board an unmanned airship. Both Fraunhofer Line Discriminator (FLD) and 3FLD used to extract ChlF require the incident solar irradiance, which is always difficult to receive at airborne level. Alternative FLD (aFLD) can overcome the problem by selecting non-fluorescent emitter in the image. However, aFLD is based on the assumption that reflectance is identical around the Fraunhofer line, which is not realistic. A new method, a3FLD, is proposed, which assumes that reflectance varies linearly with the wavelength around Fraunhofer line. The result of simulated data shows that ChlF retrieval error of a3FLD is significantly lower than that of aFLD when vegetation reflectance varies near the Fraunhofer line. The results of hyperspectral remote sensing data with the airborne fluorescence detecting system show that the relative values of retrieved ChlF of 5 kinds of plants extracted by both aFLD and a3FLD are consistent with vegetation growth stage and the ground-level ChlF. The ChlF values of aFLD are about 15% greater than a3FLD. In addition, using aFLD, some non-fluorescent objects have considerable ChlF value, while a3FLD can effectively overcome the problem. PMID:24555390

  11. Geomagnetic and strong static magnetic field effects on growth and chlorophyll a fluorescence in Lemna minor.

    Science.gov (United States)

    Jan, Luka; Fefer, Dušan; Košmelj, Katarina; Gaberščik, Alenka; Jerman, Igor

    2015-04-01

    The geomagnetic field (GMF) varies over Earth's surface and changes over time, but it is generally not considered as a factor that could influence plant growth. The effects of reduced and enhanced GMFs and a strong static magnetic field on growth and chlorophyll a (Chl a) fluorescence of Lemna minor plants were investigated under controlled conditions. A standard 7 day test was conducted in extreme geomagnetic environments of 4 µT and 100 µT as well as in a strong static magnetic field environment of 150 mT. Specific growth rates as well as slow and fast Chl a fluorescence kinetics were measured after 7 days incubation. The results, compared to those of controls, showed that the reduced GMF significantly stimulated growth rate of the total frond area in the magnetically treated plants. However, the enhanced GMF pointed towards inhibition of growth rate in exposed plants in comparison to control, but the difference was not statistically significant. This trend was not observed in the case of treatments with strong static magnetic fields. Our measurements suggest that the efficiency of photosystem II is not affected by variations in GMF. In contrast, the strong static magnetic field seems to have the potential to increase initial Chl a fluorescence and energy dissipation in Lemna minor plants. PMID:25708622

  12. Does sun-induced Chlorophyll fluorescence well capture canopy photosynthesis in a rice paddy?

    Science.gov (United States)

    Kimm, H.; Ryu, Y.; Kang, M.; Kim, J.

    2015-12-01

    Sun-induced chlorophyll fluorescence (SiF) has emerged as a convincing indicator of carbon assimilation rates under diverse environmental conditions. Here, we present a continuous observation system of SiF at a sporadically irrigated rice paddy site in South Korea. Our site also includes automatic observation systems for eddy covariance, water table depth, and spectral sensors which are composed of LED sensors, and RGB- and NIR cameras. Additionally, we conducted manual observations of photosynthetic parameters (Li-6400), leaf area index (LAI-2200), NDVI and PRI (ASD FieldSpec) once per ten days on average. By analyzing manual- and automatic field observations, we quantify carbon budget of the site. Finally, we investigate how accurately SiF detects canopy photosynthesis, and discuss what factors mainly control canopy photosynthesis.

  13. Differential responses of seven contrasting species to high light using pigment and chlorophyll a fluorescence

    Directory of Open Access Journals (Sweden)

    Mittal S.

    2011-05-01

    Full Text Available High light intensity may induce severe photodamage to chloroplast and consequently cause decreases in the yield capacity of plants and destruction of pigments, causing an overall yellowing of the foliage. Thus, study related to light adaptation becomes necessary to understand adaptation processes in higher plants on the basis of which they are characterized as full sunlight or shade plants. Chlorophyll can be regarded as an intrinsic fluorescent probe of the photosynthetic system. The ecophysiological parameter related to plant performance and fitness i.e. in-situ chlorophyll fluorescence measurements were determined for different plant species in the medicinal plant garden of Banasthali University, Rajasthan. Miniaturized Pulse Amplitude Modulated Photosynthetic Yield Analyzers are primarily designed for measuring effective quantum yield (ΔF/Fm’ of photosystem II under momentary ambient light in the field. Photosynthetic yield measurements and light-response curves suggested a gradation of sun-adapted to shade-adapted behaviour of these plants in following order Withania somnifera> Catharanthus roseus> Datura stamonium> Vasica minora> Vasica adulta> Rauwolfia serpentina. As indicated by light response curves and pigment analysis, Datura stramonium, Withania somnifera and Catharanthus roseus competed well photosynthetically and are favoured while Rauwolfia serpentina, Vasica minora, Vasica adulta and Plumbago zeylanica were observed to be less competent photosynthetically. These light response curves and resultant cardinal points study gave insight into the ecophysiological characterization of the photosynthetic capacity of the plant and provides highly interesting parameters like electron transport rate, photo-inhibition, photosynthetically active photon flux density and yield on the basis of which light adaptability was screened for seven medicinally important plants.

  14. Prospects for Chlorophyll Fluorescence Remote Sensing from the Orbiting Carbon Observatory-2

    Science.gov (United States)

    Frankenberg, Christian; Odell, Chris; Berry, Joseph; Guanter, Luis; Joiner, Joanna; Kohler, Philipp; Pollock, Randy; Taylor, Thomas E.

    2014-01-01

    The Orbiting Carbon Observatory-2 (OCO-2), scheduled to launch in July 2014, is a NASA mission designed to measure atmospheric CO2. Its main purpose is to allow inversions of net flux estimates of CO2 on regional to continental scales using the total column CO2 retrieved using high-resolution spectra in the 0.76, 1.6, and 2.0 nm ranges. Recently, it was shown that solar-induced chlorophyll fluorescence (SIF), a proxy for gross primary production (GPP, carbon uptake through photosynthesis), can be accurately retrieved from space using high spectral resolution radiances in the 750 nm range from the Japanese GOSAT and European GOME-2 instruments. Here, we use real OCO-2 thermal vacuum test data as well as a full repeat cycle (16 days) of simulated OCO-2 spectra under realistic conditions to evaluate the potential of OCO-2 for retrievals of chlorophyll fluorescence and also its dependence on clouds and aerosols. We find that the single-measurement precision is 0.3-0.5 Wm(exp -2)sr(exp -1) nm(exp -1) (15-25% of typical peak values), better than current measurements from space but still difficult to interpret on a single-sounding basis. The most significant advancement will come from smaller ground-pixel sizes and increased measurement frequency, with a 100-fold increase compared to GOSAT (and about 8 times higher than GOME-2). This will largely decrease the need for coarse spatial and temporal averaging in data analysis and pave the way to accurate local studies.We also find that the lack of full global mapping from the OCO-2 only incurs small representativeness errors on regional averages. Eventually, the combination of net ecosystem exchange (NEE) derived from CO2 source/sink inversions and SIF as proxy for GPP from the same satellite will provide a more process-based understanding of the global carbon cycle.

  15. [Effects of controlled-release fertilizer on chrysanthemum leaf chlorophyll fluorescence characteristics and ornamental quality].

    Science.gov (United States)

    Song, Xu-xu; Zheng, Cheng-shu; Sun, Xia; Ma, Hai-yan

    2011-07-01

    Taking cut flower chrysanthemum 'Baima' as test material, a pot experiment was conducted to study the effects of controlled-release fertilizer on the leaf chlorophyll fluorescence parameters, chlorophyll and nutrient contents, and ornamental quality of chrysanthemum. Under no fertilization, the maximal photochemical efficiency of PS II in dark (F(v)/F(m)), potential photochemical efficiency of PS II (F(v)/F(0)), and quantum yield of PS II electron transport (phi(PS II)) decreased significantly, compared with those under fertilization. With the application of conventional compound fertilizers CCFA (N:P:K=20:8:10) and CCFB (N:P:K= 14:14:14), the F(v)/F(m), F(v)/F(0) and phi(PS II) had a slight increase in early period (30-60 d) but a remarkable decrease in mid and later periods (75 - 120 d), compared with those under the application of controlled-release fertilizers CRFA (N:P:K = 20:8:10) and CRFB (N:P:K= 14:14:14). Under the application of CRFA, the F(v)/F(m), phi(PS II), and photochemical quenching (q(P)) had somewhat increase, as compared with the application of CRFB. The non-photochemical quenching (NPQ) under the application of CRFA and CRFB decreased significantly, compared with that under the application of CCFA and CCFB and the control. The chlorophyll content had a similar change trend with F(v)/F(m), F(v)/F(0), and phi(PS II). The leaf N, P, and K contents, flower stalk length and stalk diameter, flower diameter, and flower fresh and dry mass at harvest stage all increased under the application of CRFA and CRFB, compared with those under the application of CCFA and CCFB and the control, and the flower fresh and dry mass was significantly higher under the application of CRFA than of CRFB. This study showed that controlled-release fertilizer could improve the ornamental quality of chrysanthemum via improving the leaf chlorophyll content, photochemical transduction rate, and nutrient uptake, and CRFA had better effects than CRFB.

  16. Temperature and light tolerance of representative brown,green and red algae in tumble culture revealed by chlorophyll fluorescence measurements

    Institute of Scientific and Technical Information of China (English)

    PANG Shaojun; SHAN Tifeng

    2008-01-01

    Laminaria japonica,Undaria pinnatifida,Ulva lactuca,Grateloupia turuturu and Palmaria palmata are suitable species that fit the requirements of a seaweed-animal integrated aquaculture system in terms of their viable biomass,rapid growth and promising nutrient uptake rates. In this investigation,the responses of the optimal chlorophyll fluolescence yield of the five algal species in tumble culture were assessed at a temperature range of 10~30℃.The results revealed that Ulva lactuca was the most resistant species to high temperature,withstanding 30℃ for 4 h without apparent decline in the optimal chlorophyll fluorescence yield. While the arctic alga Palmaria palmata was the most vulnerable one,showing significant decline in the optimal chlorophyll fluorescence yield at 25℃ for 2 h.The cold-water species Laminaria japonica,however,demonstrated strong ability to cope with higher temperature(24~26℃)for shorter time(within 24 h)without significant decline in the optimal chlorophyll fluorescence yield.Grateloupia turuturu showed a general decrease in the optimal chiorophyll fluores-cence yield with the rising temperature from 23 to 30℃,similar to the temperate kelp Undaria pinnatifida.Changes of chio-rophyll fluorescence yields of these algae were characterized differently indicating the existence of species-unique strategy to cope with high light.Measurements of the optimal chlorophyll fluorescence yield after short exposure to direct solar irradiance revealed how long these exposures could be without significant photoinhibition or with promising recovery in photosynthetic activities. Seasonal pattern of alternation of algal species in tank culture in the Northern Hemisphere at the latitude of 36°Nwas proposed according to these basic measurements.

  17. Spectral effects of LEDs on chlorophyll fluorescence and pigmentation in Phalaenopsis 'Vivien' and 'Purple Star'

    DEFF Research Database (Denmark)

    Ouzounis, Theoharis; Fretté, Xavier; Ottosen, Carl-Otto;

    2015-01-01

    We examined the effect of light emitting diode (LED) lighting in greenhouse facilities on growth, chlorophyll fluorescence and pigmentation in Phalaenopsis 'Vivien' and 'Purple Star' under purpose-built LED arrays yielding c. 200μmolm-2s-1 at plant height for 14h per day and 24/18°Cday/night temp...

  18. Using violet laser-induced chlorophyll fluorescence emission spectra for crop yield assessment of cowpea (Vigna unguiculata (L) Walp) varieties

    Science.gov (United States)

    Anderson, Benjamin; Buah-Bassuah, Paul K.; Tetteh, Jonathan P.

    2004-07-01

    The use of violet laser-induced chlorophyll fluorescence (LICF) emission spectra to monitor the growth of five varieties of cowpea in the University of Cape Coast Botanical Garden is presented. Radiation from a continuous-wave violet laser diode emitting at 396 nm through a fibre is closely incident on in vivo leaves of cowpea to excite chlorophyll fluorescence, which is detected by an integrated spectrometer with CCD readout. The chlorophyll fluorescence spectra with peaks at 683 and 731 nm were used for growth monitoring of the cowpea plants over three weeks and analysed using Gaussian spectral functions with curve fitted parameters to determine the peak positions, area under the spectral curve and the intensity ratio F683/F731. The variation in the intensity ratio of the chlorophyll bands showed sensitive changes indicating the photosynthetic activity of the cowpea varieties. A discussion of the fluorescence result as compared to conventional assessment is presented with regard to discrimination between the cowpea varieties in terms of crop yield performance.

  19. Chlorophyll fluorescence as a parameter for frost hardiness in winter wheat. A comparison with other hardiness parameters.

    NARCIS (Netherlands)

    Clement, JMAM; vanHasselt, PR

    1996-01-01

    Frost hardiness of winter wheat leaves (Triticum aestivum L. cv. Urban) was measured during an eight weeks hardening period using chlorophyll fluorescence. Determination of frost induced damage after freezing, measured as the decrease of photochemical capacity of photosystem II (F-V/F-M = (F-M-F-O)F

  20. Method 445.0 In Vitro Determination of Chlorophyll a and Pheophytin ain Marine and Freshwater Algae by Fluorescence

    Science.gov (United States)

    This method provides a procedure for low level determination of chlorophyll a (chl a) and its magnesium free derivative, pheophytin a (pheo a), in marine and freshwater phytoplankton using fluorescence detection.(1,2) Phaeophorbides present in the sample are determined collective...

  1. Effect of four levels of shade on survival, morphology and chlorophyll fluorescence of Nothofagus alessandrii container-grown seedlings

    Directory of Open Access Journals (Sweden)

    Santelices R

    2015-10-01

    Full Text Available Nothofagus alessandrii (ruil is a threatened, endemic tree of the Mediterranean zone of Chile. As a result of past anthropogenic activities, its current cover has been reduced to only 314 hectares across several fragmented and degraded areas. Although activities to conserve and recover such forests have been developed, little is known about their propagation and nursery cultivation, since the plant’s quality is one of the most important factors for restoration and reforestation plans, re-vegetation, or forest enrichment. The success of restoration programs in these areas will require improvements in plant production, being important to test the shade effects on seedling survival and growth. This paper reports the results of testing for survival, morphological and chlorophyll fluorescence differences in N. alessandrii seedlings grown for approximately 32 weeks in unshaded conditions and under three different levels of shading (18%, 50%, and 80% shade. Morphological traits (stem height, root collar diameter, specific leaf area, shoot and root biomass, and quality indexes and survival were measured. Chlorophyll fluorescence was also measured to analyze the shade tolerance of the species. Analysis showed significant differences for most traits as a consequence of the shade level. Seedlings exposed to 18% shade showed the highest total dry biomass, while those exposed to 80% shade showed the highest survival rate (92%. Chlorophyll fluorescence was high in the unshaded conditions and medium in the 18-50% shade. Morphological and chlorophyll fluorescence responses differed greatly among shade levels and corresponded with the degree of shade tolerance of the species.

  2. Effects of ambient versus reduced UV-B radiation on high arctic Salix arctica assessed by measurements and calculations of chlorophyll-a fluorescence parameters from fluorescence transients

    DEFF Research Database (Denmark)

    Albert, Kristian Rost

    2005-01-01

    received approximately 90 and 40% of the ambient UV-B irradiance, respectively. The effects were examined through recordings of chlorophyll a fluorescence transients, determination of biomass and analysis of total carbon and nitrogen content and amount of soluble flavonoids in the leaves. The processing...... of light was analysed by means of the chlorophyll a fluorescence transient, using the so-called JIP test, as evolved by Reto J. Strasser and his coworkers. Reduction of the UV-B irradiance caused a rise in many of the fluorescence parameters during July, but not in August (late season). Thus increases...... on fluorescence parameters that were directly measured (e.g. F0 and FM) and those that were derived (e.g. quantum efficiencies, parameters per PSII reaction centres and per cross-section of leaf sample) are discussed in relation to one another, in relation to daily and seasonal variation, and from the perspective...

  3. Diurnal Variability in Chlorophyll-a, Carotenoids, CDOM and SO₄(2-) Intensity of Offshore Seawater Detected by an Underwater Fluorescence-Raman Spectral System.

    Science.gov (United States)

    Chen, Jing; Ye, Wangquan; Guo, Jinjia; Luo, Zhao; Li, Ying

    2016-01-01

    A newly developed integrated fluorescence-Raman spectral system (λex = 532 nm) for detecting Chlorophyll-a (chl-a), Chromophoric Dissolved Organic Matter (CDOM), carotenoids and SO₄(2-) in situ was used to successfully investigate the diurnal variability of all above. Simultaneously using the integration of fluorescence spectroscopy and Raman spectroscopy techniques provided comprehensive marine information due to the complementarity between the different excitation mechanisms and different selection rules. The investigation took place in offshore seawater of the Yellow Sea (36°05'40'' N, 120°31'32'' E) in October 2014. To detect chl-a, CDOM, carotenoids and SO₄(2-), the fluorescence-Raman spectral system was deployed. It was found that troughs of chl-a and CDOM fluorescence signal intensity were observed during high tides, while the signal intensity showed high values with larger fluctuations during ebb-tide. Chl-a and carotenoids were influenced by solar radiation within a day cycle by different detection techniques, as well as displaying similar and synchronous tendency. CDOM fluorescence cause interference to the measurement of SO₄(2-). To avoid such interference, the backup Raman spectroscopy system with λex = 785 nm was employed to detect SO₄(2-) concentration on the following day. The results demonstrated that the fluorescence-Raman spectral system has great potential in detection of chl-a, carotenoids, CDOM and SO₄(2-) in the ocean. PMID:27420071

  4. The effect of UV-B and UV-C radiation on Hibiscus leaves determined by ultraweak luminescence and fluorescence induction [chlorophyll fluorescence induction, ultraweak luminescence

    International Nuclear Information System (INIS)

    The effects of UV-C (254 nm) and UV-B (280-320 nm) on chlorophyll fluorescence induction and ultraweak luminescence (UL) in detached leaves of Hibiscus rosa-sinensis L. were investigated. UL from leaves exposed to UV-B and UV-C radiation reached a maximum 72 h after irradiation. In both cases most of the light was of a wavelength over 600 nm. An increase in the percentage of long wavelength light with time was detected. UV radiation increased peroxidase activity, which also reached a maximum 72 h after irradiation. UV-B and UV-C both reduced variable chlorophyll fluorescence. No effect on the amount of chlorophyll or UV screening pigments was observed with the short-term irradiation used in this investigation. (author)

  5. Effect of Methanol on Photosynthesis and Chlorophyll Fluorescence of Flag Leaves of Winter Wheat

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yue-jin; YANG Yue-qin; LIANG Shan-shan; YI Xian-feng

    2008-01-01

    Photosynthesis and chlorophyll a fluorescence parameters, photochemical efficiency of PS II (Fv/Fm), photochemical quenching of PS II (qP), nonphotochemical quenching of PS II (NPQ), maximum activity of PS II (Fv/Fo) as well as electron transport rate (ETR), and quantum yield of PS II (ΦPS II) were measured on flag leaves of the winter wheat treated by methanol at different concentrations. The results revealed that photosynthesis was greatly improved by methanol, as indicated by higher photosynthetic rates and stomatal conductance. The enhancement effect of methanol on photosynthesis was maintained for 3-4 days. Different methanol concentration treatments also increased intercellular CO2 concentration and transpiration rates. No significant decline was found in Fv/Fm, Fv/Fo, and ΦPS II, which revealed no photoinhibition during methanol application in different methanol concentrations. Methanol showing no apparent inhibitory effects indicated higher potential photosynthetic capacity of flag leaves of winter wheat. However, the increase in photosynthesis was not followed by an increase in the photosynthetic activity (Fv/Fm), and fluorescence parameters did not indicate an improvement in intercellular CO2 concentration and PS II photochemical efficiency compared with the control, thereby encouraging us to propose that lower leaf temperatures caused by applied methanol would reduce both dark respiration and photorespiration (most importantly), thus, increasing net CO2 uptake and photosynthetic rates.

  6. Alterations in Chlorophyll a Fluorescence and Pigments Concentration in the Leaves of Cauliflower and Broccoli Transplants Subjected to Chilling

    Directory of Open Access Journals (Sweden)

    Renata WOJCIECHOWSKA

    2016-06-01

    Full Text Available Chlorophyll a fluorescence parameters and photosynthetic pigments content in leaves of broccoli (Brassica oleracea L. var. italica cv. ‘Monaco’ F1 and cauliflower (Brassica oleracea L. var. botrytis cv. ‘Bruce’ F1 transplants were analyzed to investigate the effects of chilling temperatures (6 and 10 °C and the exposure length (1 or 2 weeks on the photosynthetic apparatus condition in 3-year experiment. Data were compared to control plants exposed to 14 °C for 1 and 2 weeks. The lowest values of maximum quantum efficiency of photosystem II (Fv/Fm and the performance index (PI were observed in cauliflower chilled at 6 °C for 2 weeks. This was not accompanied by any substantial reduction in chlorophylls concentration, however, significant correlations between Fv/Fm or PI and chlorophylls content in cauliflower leaves were found. There was no negative effects of chilling on photosynthetic activity and chlorophyll content in broccoli leaves, the amount of carotenoids significantly increased in the broccoli chilled for 2 weeks in 6 °C. The chlorophyll a fluorescence indices and accelerated carotenoids synthesis showed that broccoli had less vulnerable photosynthetic apparatus to stress-induced temperatures and more efficient protection mechanisms in comparison to cauliflower transplants.

  7. Multispectral In-situ Measurements of Organic Matter and Chlorophyll Fluorescence in Seawater: Documenting the Intrusion of the Mississippi River Plume in the West Florida Shelf

    Science.gov (United States)

    DelCastillo, Carlos E.; Coble, Paula G.; Conmy, Robyn N.; Mueller-Karger, Frank E.; Vanderbloomen, Lisa; Vargo, Gabriel A.

    2000-01-01

    We performed multispectral in-situ fluorescence measurement of colored dissolved organic matter and chlorophyll in surface water of the West Florida Shelf using West Labs Spectral absorption and Fluorescence Instrument (SAFIre). Continuous measurements underway allowed us to simultaneously map the dispersion of riverine organic material and chlorophyll on the shelf. By using two fluorescence emission ratios we were able to differentiate between riverine and marine CDOM. Our data also showed unusually high concentrations of CDOM offshore. These were attributed to an intrusion of the Mississippi River Plume. We performed limited comparisons between in-situ chlorophyll concentrations measured with SAFIre and chlorophyll values obtained from SeaWiFS satellite data using OC4 and MODIS algorithm. Our results show that, although both algorithms overestimated chlorophyll, MODIS performed better than OC4, particularly in areas with high CDOM concentrations. Analysis of the relationship between chlorophyll and CDOM concentrations within the study area showed regional variability causes by differences in river source.

  8. Potential of chlorophyll fluorescence imaging for assessing bio-viability changes of biodeteriogen growths on stone monuments

    Science.gov (United States)

    Osticioli, I.; Mascalchi, M.; Pinna, D.; Siano, S.

    2013-05-01

    A systematic study on the use of Chlorophyll Fluorescence (CF) imaging in Pulsed Amplitude Modulated (PAM) for assessing viability changes of biodeteriogen on stone artifacts has been carried out. The experimentation has been performed on different phototrophic organisms of gravestone slabs from the monumental British Cemetery of Florence (Italy). Since the viability of these organisms and then their chlorophyll fluorescence emission is strongly dependent on the environmental conditions, a preliminary study on the effects of local patterns during the season was carried out. The trend of the fluorescence quantum yield (QYmax) at different dark adapted times in different periods of the year was determined. The results achieved in our work proves the effectiveness of the CF-PAM imaging for in situ lichen characterizations in conservation studies and defines an optimized application protocol.

  9. Estimating chlorophyll content and photochemical yield of photosystem II (ΦPSII) using solar-induced chlorophyll fluorescence measurements at different growing stages of attached leaves.

    Science.gov (United States)

    Tubuxin, Bayaer; Rahimzadeh-Bajgiran, Parinaz; Ginnan, Yusaku; Hosoi, Fumiki; Omasa, Kenji

    2015-09-01

    This paper illustrates the possibility of measuring chlorophyll (Chl) content and Chl fluorescence parameters by the solar-induced Chl fluorescence (SIF) method using the Fraunhofer line depth (FLD) principle, and compares the results with the standard measurement methods. A high-spectral resolution HR2000+ and an ordinary USB4000 spectrometer were used to measure leaf reflectance under solar and artificial light, respectively, to estimate Chl fluorescence. Using leaves of Capsicum annuum cv. 'Sven' (paprika), the relationships between the Chl content and the steady-state Chl fluorescence near oxygen absorption bands of O2B (686nm) and O2A (760nm), measured under artificial and solar light at different growing stages of leaves, were evaluated. The Chl fluorescence yields of ΦF 686nm/ΦF 760nm ratios obtained from both methods correlated well with the Chl content (steady-state solar light: R(2) = 0.73; artificial light: R(2) = 0.94). The SIF method was less accurate for Chl content estimation when Chl content was high. The steady-state solar-induced Chl fluorescence yield ratio correlated very well with the artificial-light-induced one (R(2) = 0.84). A new methodology is then presented to estimate photochemical yield of photosystem II (ΦPSII) from the SIF measurements, which was verified against the standard Chl fluorescence measurement method (pulse-amplitude modulated method). The high coefficient of determination (R(2) = 0.74) between the ΦPSII of the two methods shows that photosynthesis process parameters can be successfully estimated using the presented methodology.

  10. Effects of Dihydroartemisinin and Artemether on the Growth, Chlorophyll Fluorescence, and Extracellular Alkaline Phosphatase Activity of the Cyanobacterium Microcystis aeruginosa

    Science.gov (United States)

    Wang, Shoubing; Xu, Ziran

    2016-01-01

    Increased eutrophication in the recent years has resulted in considerable research focus on identification of methods for preventing cyanobacterial blooms that are rapid and efficient. The objectives of this study were to investigate the effects of dihydroartemisinin and artemether on the growth of Microcystis aeruginosa and to elucidate its mode of action. Variations in cell density, chlorophyll a, soluble protein, malondialdehyde, extracellular alkaline phosphatase activity (APA), and chlorophyll fluorescence parameters (Fv/Fm, ΦPSII, ETR, rapid light curves, fast chlorophyll fluorescence curves on fluorescence intensity, and relative variable fluorescence) were evaluated by lab-cultured experiments. Our results demonstrated that both dihydroartemisinin and artemether inhibited the growth of M.aeruginosa by impairing the photosynthetic center in photosystem II and reducing extracellular APA, with a higher sensitivity exhibited toward artemether. The inhibitory effects of dihydroartemisinin on M.aeruginosa increased with concentration, and the maximum growth inhibitory rate was 42.17% at 24 mg·L-1 after 120h exposure, whereas it was 55.72% at 6 mg·L-1 artemetherafter 120h exposure. Moreover, the chlorophyll fluorescence was significantly inhibited (p<0.05) after 120h exposure to 12 and 24 mg·L-1 dihydroartemisinin. Furthermore, after 120h exposure to 6 mg·L-1 artemether, Fv/Fm, ΦPSII, ETR and rETRmax showed a significant decrease (p<0.01) from initial values of 0.490, 0.516, 17.333, and 104.800, respectively, to 0. One-way analysis of variance showed that 6 mg·L-1 artemether and 24 mg·L-1 dihydroartemisinin had significant inhibitory effects on extracellular APA (p<0.01). The results of this study would be useful to further studies to validate the feasibility of dihydroartemisinin and artemether treatment to inhibit overall cyanobacterial growth in water bodies, before this can be put into practice. PMID:27755566

  11. Short-duration exposure to radiofrequency electromagnetic radiation alters the chlorophyll fluorescence of duckweeds (Lemna minor).

    Science.gov (United States)

    Senavirathna, Mudalige Don Hiranya Jayasanka; Takashi, Asaeda; Kimura, Yuichi

    2014-12-01

    Plants growing in natural environments are exposed to radiofrequency electromagnetic radiation (EMR) emitted by various communication network base stations. The environmental concentration of this radiation is increasing rapidly with the congested deployment of base stations. Although numerous scientific studies have been conducted to investigate the effects of EMR on the physiology of humans and animals, there have been few attempts to investigate the effects of EMR on plants. In this study, we attempted to evaluate the effects of EMR on photosynthesis by investigating the chlorophyll fluorescence (ChF) parameters of duckweed fronds. During the experiment, the fronds were tested with 2, 2.5, 3.5, 5.5 and 8 GHz EMR frequencies, which are not widely studied even though there is a potentially large concentration of these frequencies in the environment. The duckweed fronds were exposed to EMR for 30 min, 1 h and 24 h durations with electric field strength of 45-50 V/m for each frequency. The results indicated that exposure to EMR causes a change in the non-photochemical quenching of the duckweeds. The changes varied with the frequency of the EMR and were time-varying within a particular frequency. The temperature remained unchanged in the duckweed fronds upon exposure to EMR, which confirms that the effect is non-thermal.

  12. Validation of the chlorophyll fluorescence imaging method (CFI for early detection of herbicide resistance in weeds

    Directory of Open Access Journals (Sweden)

    Menegat, Alexander

    2014-02-01

    Full Text Available The increasing number of herbicide tolerant weed populations is illustrating the increasing demand for reliable methods for an accelerated detection of herbicide tolerance compared to greenhouse studies. Several methods for resistance quick detection have been published in previous years. One of the recent methods is the Chlorophyll Fluorescence Imaging Method (CFI. For this method changes in photosynthetic activity of the target organisms, caused by herbicides, are determined. General assumption of this method in terms of herbicide resistance detection is that each herbicidal compound, independent of the mode of action, will cause changes within the photosynthetic apparatus of the target organisms. This effect already could be confirmed for several modes of action (PSII, ALS, ACCase, EPSPS, synth. Auxins. Aim of this study is to validate this novel method on the basis of greenhouse experiments and single nucleotide polymorphisms (SNP analysis. The resistance profiles of 10 black-grass populations (Alopecurus myosuroides Huds. have been determined in greenhouse herbicide efficacy trials and constitutive SNP analyses of the survivors. With the CFI-method it was possible to detect the resistance profile as well as the resistance frequency within the populations. The results from the greenhouse experiments could be reproduced with conformity of 94%. This result is valid for the tested herbicides mesosulfuron, pyroxsulam as well as clodinafop and pinoxaden.

  13. Global and Time-Resolved Monitoring of Crop Photosynthesis with Chlorophyll Fluorescence

    Science.gov (United States)

    Guanter, Luis; Zhang, Yongguang; Jung, Martin; Joiner, Joanna; Voigt, Maximilian; Berry, Joseph A.; Frankenberg, Christian; Huete, Alfredo R.; Zarco-Tejada, Pablo; Lee, Jung-Eun; Moran, M. Susan; Ponce-Campos, Guillermo; Beer, Christian; Camps-Valls, Gustavo; Buchmann, Nina; Gianelle, Damiano; Klumpp, Katja; Cescatti, Alessandro; Baker, John M.; Griffis, Timothy J.

    2014-01-01

    Photosynthesis is the process by which plants harvest sunlight to produce sugars from carbon dioxide and water. It is the primary source of energy for all life on Earth; hence it is important to understand how this process responds to climate change and human impact. However, model-based estimates of gross primary production (GPP, output from photosynthesis) are highly uncertain, in particular over heavily managed agricultural areas. Recent advances in spectroscopy enable the space-based monitoring of sun-induced chlorophyll fluorescence (SIF) from terrestrial plants. Here we demonstrate that spaceborne SIF retrievals provide a direct measure of the GPP of cropland and grassland ecosystems. Such a strong link with crop photosynthesis is not evident for traditional remotely sensed vegetation indices, nor for more complex carbon cycle models. We use SIF observations to provide a global perspective on agricultural productivity. Our SIF-based crop GPP estimates are 50-75% higher than results from state-of-the-art carbon cycle models over, for example, the US Corn Belt and the Indo-Gangetic Plain, implying that current models severely underestimate the role of management. Our results indicate that SIF data can help us improve our global models for more accurate projections of agricultural productivity and climate impact on crop yields. Extension of our approach to other ecosystems, along with increased observational capabilities for SIF in the near future, holds the prospect of reducing uncertainties in the modeling of the current and future carbon cycle.

  14. Analysis of chlorophyll fluorescence reveals stage specific patterns of chloroplast-containing cells during Arabidopsis embryogenesis.

    Science.gov (United States)

    Tejos, Ricardo I; Mercado, Ana V; Meisel, Lee A

    2010-01-01

    The basic body plan of a plant is established early in embryogenesis when cells differentiate, giving rise to the apical and basal regions of the embryo. Using chlorophyll fluorescence as a marker for chloroplasts, we have detected specific patterns of chloroplast-containing cells at specific stages of embryogenesis. Non-randomly distributed chloroplast-containing cells are seen as early as the globular stage of embryogenesis in Arabidopsis. In the heart stage of embryogenesis, chloroplast containing cells are detected in epidermal cells as well as a central region of the heart stage embryo, forming a triangular septum of chloroplast-containing cells that divides the embryo into three equal sectors. Torpedo stage embryos have chloroplast-containing epidermal cells and a central band of chloroplast-containing cells in the cortex layer, just below the shoot apical meristem. In the walking-stick stage of embryogenesis, chloroplasts are present in the epidermal, cortex and endodermal cells. The chloroplasts appear reduced or absent from the provascular and columella cells of walking-stick stage embryos. These results suggest that there is a tight regulation of plastid differentiation during embryogenesis that generates specific patterns of chloroplast-containing cells in specific cell layers at specific stages of embryogenesis.

  15. The characteristics of CO2 as- similation of photosynthesis and chlorophyll fluorescence in transgenic PEPC rice

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    With PEPC, PPDK, NADP-ME and PEPC+ PPDK transgenic and untransformed rice (Orysa sativa L.), the activities of related C4 photosynthesis enzymes, the chlorophyll fluorescence parameters, CO2 exchange and other physiological indexes were compared, in which the physiological characteristics of PEPC transgenic rice were mainly studied. The results were as follows: (ⅰ) The activi- ties of PEPC in PEPC transgenic rice were 20-fold higher than those in untransformed rice; the light-saturation photosynthetic rates and the carboxylation efficiency of PEPC transgenic rice were increased by 55% and 50% more than those of untransformed rice, respectively, while the CO2 compensation point decreased by 27%. (ⅱ) The PSⅡ photochemical efficiency (Fv/Fm) and photochemical quenching (qP) of transgenic PEPC rice decreased less in comparison with those of untransformed rice after the treatment with high light intensity (3 h) or methyl viologen (MV), a photooxidative reagent, which demonstrated that the tolerance of PEPC transgenic rice to photoinhibition and photooxidation was enhanced. (ⅲ) Under the condition of high light intensity, the activity of RuBPCase in PEPC transgenic rice did not obviously vary while the activity in- duced of carbonic anhydrase (CA) in PEPC transgenic rice increased by 1.8 fold. These results would provide some beneficial enlightment for revealing the mechanism of high photosynthetic efficiency and breeding with high photosyn- thetic efficiency in rice.

  16. Global Monitoring of Terrestrial Chlorophyll Fluorescence from Moderate-spectral-resolution Near-infrared Satellite Measurements: Methodology, Simulations, and Application to GOME-2

    Science.gov (United States)

    Joiner, J.; Gaunter, L.; Lindstrot, R.; Voigt, M.; Vasilkov, A. P.; Middleton, E. M.; Huemmrich, K. F.; Yoshida, Y.; Frankenberg, C.

    2013-01-01

    Globally mapped terrestrial chlorophyll fluorescence retrievals are of high interest because they can provide information on the functional status of vegetation including light-use efficiency and global primary productivity that can be used for global carbon cycle modeling and agricultural applications. Previous satellite retrievals of fluorescence have relied solely upon the filling-in of solar Fraunhofer lines that are not significantly affected by atmospheric absorption. Although these measurements provide near-global coverage on a monthly basis, they suffer from relatively low precision and sparse spatial sampling. Here, we describe a new methodology to retrieve global far-red fluorescence information; we use hyperspectral data with a simplified radiative transfer model to disentangle the spectral signatures of three basic components: atmospheric absorption, surface reflectance, and fluorescence radiance. An empirically based principal component analysis approach is employed, primarily using cloudy data over ocean, to model and solve for the atmospheric absorption. Through detailed simulations, we demonstrate the feasibility of the approach and show that moderate-spectral-resolution measurements with a relatively high signal-to-noise ratio can be used to retrieve far-red fluorescence information with good precision and accuracy. The method is then applied to data from the Global Ozone Monitoring Instrument 2 (GOME-2). The GOME-2 fluorescence retrievals display similar spatial structure as compared with those from a simpler technique applied to the Greenhouse gases Observing SATellite (GOSAT). GOME-2 enables global mapping of far-red fluorescence with higher precision over smaller spatial and temporal scales than is possible with GOSAT. Near-global coverage is provided within a few days. We are able to show clearly for the first time physically plausible variations in fluorescence over the course of a single month at a spatial resolution of 0.5 deg × 0.5 deg

  17. Effects of nitrogen form on growth, CO2 assimilation, chlorophyll fluorescence, and photosynthetic electron allocation in cucumber and rice plants*

    OpenAIRE

    Zhou, Yan-Hong; Zhang, Yi-li; Wang, Xue-Min; Cui, Jin-xia; Xia, Xiao-Jian; Kai SHI; Yu, Jing-quan

    2011-01-01

    Cucumber and rice plants with varying ammonium (NH4 +) sensitivities were used to examine the effects of different nitrogen (N) sources on gas exchange, chlorophyll (Chl) fluorescence quenching, and photosynthetic electron allocation. Compared to nitrate (NO3 −)-grown plants, cucumber plants grown under NH4 +-nutrition showed decreased plant growth, net photosynthetic rate, stomatal conductance, intercellular carbon dioxide (CO2) level, transpiration rate, maximum phot...

  18. Potential of the TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor for the monitoring of terrestrial chlorophyll fluorescence

    OpenAIRE

    Guanter, L.; Aben, I.; P. Tol; Krijger, J. M.; A. Hollstein; Köhler, P.; A. Damm; Joiner, J.; Frankenberg, C.; Landgraf, J.

    2015-01-01

    Global monitoring of sun-induced chlorophyll fluorescence (SIF) is improving our knowledge about the photosynthetic functioning of terrestrial ecosystems. The feasibility of SIF retrievals from spaceborne atmospheric spectrometers has been demonstrated by a number of studies in the last years. In this work, we investigate the potential of the upcoming TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor satellite mission for SIF retrieval. TROPOMI wi...

  19. Characteristics of Gas Exchange and Chlorophyll Fluorescence in Different Position Leaves at Booting Stage in Rice Plants

    Institute of Scientific and Technical Information of China (English)

    Mo Yi-wei; JIN Song-heng; WANG Zhong; WANG Pin-mei; QIAN Shan-qin; ZHAO Kai; GU Yun-jie; YANG Yi-qing; YAO Sheng; JIANG De-an

    2004-01-01

    To investigate the senescence of rice leaves at different positions at booting stage, gas exchange and chlorophyll fluorescence properties in leaves at different positions were examined by using six rice materials. The net rates of photosynthesis (Pn),stomatal conductance (gs), transpiration rate (E) and water use efficiency (WUE) decreased significantly with lowering of leaf positions,while intercellular CO2 concentration (Cj) had a little change, indicating that the decrease of photosynthetic rate was not resulted from the decrease of gs. The decrease of SPAD reading which had a close correlation with chlorophyll content was one of apparent reasons resulting in the decease of Pn. Further evidence by chlorophyll fluorescence showed that the photochemical efficiency of PS Ⅱ and its electron transport rate (ETR) decreased substantially with lowering of the leaf positions but the variable-to-maximum fluorescence ratio(Fv/Fm) and efficiency of energy conversion of open PS Ⅱ (Fv'/Fm') remained rather stable, suggesting that primary limitation of Pn was suppression of electron transport of PS Ⅰ, and probably associated with carbon assimilation.

  20. Spatial location of photosystem pigment-protein complexes in thylakoid membranes of chloroplasts of Pisum sativum studied by chlorophyll fluorescence

    International Nuclear Information System (INIS)

    Ultrastructure of plant chloroplasts was studied by a single-molecule spectroscopy setup at a temperature of 77 K exploring spatial location of photosystems. Two chloroplast thylakoid membrane regions were visualized by fluorescence microscopy and detected at different wavelengths. The size of these regions and the spatial resolution of the microscope allowed us to measure their chlorophyll fluorescence emission spectra of these membrane domains. While the grana regions are characterized by a predominant presence of Photosystem II pigment-protein complexes emitting at 685 nm, Photosystem I complexes are localized in stroma regions and emit at 730 nm

  1. Phenology and gross primary production of maize croplands from chlorophyll light absorption, solar-induced chlorophyll fluorescence and CO2 flux tower approaches

    Science.gov (United States)

    Zhang, Yongguang; Wagle, Pradeep; Guanter, Luis; Jin, Cui; Xiao, Xiangming

    2015-04-01

    It is important to accurately quantify cropland gross primary productivity (GPP) for monitoring cropland status and the carbon budgets. Both sattellite-based light-use efficiency (LUE) models and process-based terrestrial biosphere models (TBM) have been widely used to quantify cropland GPP at different scales. Space-borne solar-induced chlorophyll fluorescence (SIF) has recently shown the ability to monitor photosynthesis from space. In this presentation, we compared the three approaches for estimating seasonal dynamics and magnitudes of maize cropland GPP during 2007-2011 at a cropland site in Nebraska, USA. Three approaches used were a satellite-based Vegetation Photosynthsis Model (VPM) with the concept of light absorption by chlorophyll, the process-based Soil-Canopy Observation of Photosynthesis and Energy (SCOPE), and space-borne SIF. Validations against flux tower estimates demonstrate that maize GPP can be accurately estimated with the three models. The SCOPE model provides the best simulation of maize GPP by incorporation of satellite SIF measurements. On the other hand, satellite-based VPM model shows the potential for scaling-up GPP estimation of intensified managed croplands with higher spatial resolution data from MODIS. The results show that the space-borne SIF data can be simply and directly used not only to monitor actual photosynthesis of crop without much ancillary information, but also to improve cropland GPP modeling by constraining process-based TBM.

  2. Underwater Optical Fiber Fluorescent System for Measuring Chlorophyll-a Concentration

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Using optical fiber fluorescent technology,a new method for measuring alga concentration in water is presented. The system can realize on-line measurement for alga concentration using He-Ne laser as the light source. It can also effectively detect weak signals. The system with a passive sensor head has such advantages as simple structure, high sensitivity and high accuracy. It has been demonstrated that this system can be used to monitor water quality and can also be used to survey some matter.

  3. Quality assessment of urban trees using growth visual and chlorophyll fluorescence indicators

    Directory of Open Access Journals (Sweden)

    Uhrin Peter

    2016-06-01

    Full Text Available Urbanised landscape represents composed structures of technical and biotic elements where social and economy activities create living space for human society but with strongly changed environment. To dominant characters belong climate changes with increased air temperature, drought and emission load, which has developed wide spectrum of stress factors influencing the urban vegetation. For the assessment of plant growth and adaptation response, we have used Sycamore maple (Acer pseudoplatanus L. as study model woody plant. In the framework of visual characters, we assessed the following indicators: (a assimilation organs (leaf necrosis; (b crown quality (degree of foliage and degree of dead tree crown; (c trunk and branch quality (mechanical damage, incidence of wood destroying fungus and trunk cavities and callus healing of trunk wounds. Each indicator was assessed in five-point scale, and in the end, the common index of quality was calculated. The quality index achieved 9.33 points in the first and 10.33 in the second evaluation periods in the Nitra city and 2.66 at the both assessed periods in the comparable rural park. In the group of physiological indicators, chlorophyll a fluorescence marker and its Fv/Fm parameter were used. Within three repeating assessment during growing season (June, August and September, the average values reached Fv/Fm = 0.814 in the city and Fv/Fm = 0.829 in rural park. The results confirmed statistical significances between loaded city conditions and relatively clean rural locality. Used markers have shown as appropriate tools for growth response measurements of street trees in a changed urban environment.

  4. Global Monitoring of Terrestrial Chlorophyll Fluorescence from Space: Status and Potential for Carbon Cycle Research

    Science.gov (United States)

    Guanter, L.; Koehler, P.; Walther, S.; Zhang, Y.; Joiner, J.; Frankenberg, C.

    2015-12-01

    Gross primary production (GPP), or the amount of atmospheric CO2 fixed by vegetation through photosynthesis, represents the largest carbon flux between terrestrial ecosystems and the atmosphere. Despite its importance, large-scale estimates of GPP remain highly uncertain for some terrestrial ecosystems. In this context, measurements of sun-induced chlorophyll fluorescence (SIF), which is emitted in the 650-850nm spectral range by the photosynthetic apparatus of green plants, have the potential to provide a new view on vegetation photosynthesis. Global monitoring of SIF from space have been achieved in the last years by means of a number of atmospheric spectrometers, which have turned out to provide the necessary spectral and radiometric sensitivity for SIF retrieval. The first global measurements of SIF were achieved in 2011 from spectra acquired by the Japanese GOSAT mission. This breakthorugh was followed by retrievals from the Global Ozone Monitoring Experiment-2 (GOME-2) instruments onboard MetOp-A and MetOp-B, which enable a continuous spatial sampling, and lately from ENVISAT/SCIAMACHY. This observational scenario is completed by the first SIF data from the NASA-JPL OCO-2 mission (launched in July 2014) and the upcoming Copernicus' Sentinel 5-Precursor to be launched by early 2016. OCO-2 and TROPOMI offer the possibility of monitoring SIF globally with a 100-fold improvement in spatial and temporal resolution with respect to GOSAT, GOME-2 and SCIAMACHY.In this contribution, we will provide an overview of global SIF monitoring and will illustrate the potential of SIF data to improve our knowledge of vegetation photosynthesis and GPP at the synoptic scale. We will show examples of ongoing research exploiting SIF data for an improved monitoring of photosynthetic activity at different ecosystems, highlighting the usefulness of SIF to constrain estimates of CO2 uptake by vegetation through photosynthesis.

  5. Consistency Between Sun-Induced Chlorophyll Fluorescence and Gross Primary Production of Vegetation in North America

    Science.gov (United States)

    Zhang, Yao; Xiao, Xiangming; Jin, Cui; Dong, Jinwei; Zhou, Sha; Wagle, Pradeep; Joiner, Joanna; Guanter, Luis; Zhang, Yongguang; Zhang , Geli; Qin, Yuanwei; Wang, Jie; Moore, Berrien, III

    2016-01-01

    Accurate estimation of the gross primary production (GPP) of terrestrial ecosystems is vital for a better understanding of the spatial-temporal patterns of the global carbon cycle. In this study,we estimate GPP in North America (NA) using the satellite-based Vegetation Photosynthesis Model (VPM), MODIS (Moderate Resolution Imaging Spectrometer) images at 8-day temporal and 500 meter spatial resolutions, and NCEP-NARR (National Center for Environmental Prediction-North America Regional Reanalysis) climate data. The simulated GPP (GPP (sub VPM)) agrees well with the flux tower derived GPP (GPPEC) at 39 AmeriFlux sites (155 site-years). The GPP (sub VPM) in 2010 is spatially aggregated to 0.5 by 0.5-degree grid cells and then compared with sun-induced chlorophyll fluorescence (SIF) data from Global Ozone Monitoring Instrument 2 (GOME-2), which is directly related to vegetation photosynthesis. Spatial distribution and seasonal dynamics of GPP (sub VPM) and GOME-2 SIF show good consistency. At the biome scale, GPP (sub VPM) and SIF shows strong linear relationships (R (sup 2) is greater than 0.95) and small variations in regression slopes ((4.60-5.55 grams Carbon per square meter per day) divided by (milliwatts per square meter per nanometer per square radian)). The total annual GPP (sub VPM) in NA in 2010 is approximately 13.53 petagrams Carbon per year, which accounts for approximately 11.0 percent of the global terrestrial GPP and is within the range of annual GPP estimates from six other process-based and data-driven models (11.35-22.23 petagrams Carbon per year). Among the seven models, some models did not capture the spatial pattern of GOME-2 SIF data at annual scale, especially in Midwest cropland region. The results from this study demonstrate the reliable performance of VPM at the continental scale, and the potential of SIF data being used as a benchmark to compare with GPP models.

  6. Vegetation Red-edge Spectral Modeling for Solar-induced Chlorophyll Fluorescence Retrieval at O2-B Band

    Science.gov (United States)

    Huang, C.; Zhang, L.; Qiao, N.; Zhang, X.; Li, Y.

    2015-12-01

    Remotely sensed solar-induced chlorophyll fluorescence (SIF) has been considered an ideal probe in monitoring global vegetation photosynthesis. However, challenges in accurate estimate of faint SIF (less than 5% of the total reflected radiation in near infrared bands) from the observed apparent reflected radiation greatly limit its wide applications. Currently, the telluric O2-B (~688nm) and O2-A (~761nm) have been proved to be capable of SIF retrieval based on Fraunhofer line depth (FLD) principle. They may still work well even using conventional ground-based commercial spectrometers with typical spectral resolutions of 2~5 nm and high enough signal-to-noise ratio (e.g., the ASD spectrometer). Nevertheless, almost all current FLD based algorithms were mainly developed for O2-A, a few concentrating on the other SIF emission peak in O2-B. One of the critical reasons is that it is very difficult to model the sudden varying reflectance around O2-B band located in the red-edge spectral region (about 680-800 nm). This study investigates a new method by combining the established inverted Gaussian reflectance model (IGM) and FLD principle using diurnal canopy spectra with relative low spectral resolutions of 1 nm (FluorMOD simulations) and 3 nm (measured by ASD spectrometer) respectively. The IGM has been reported to be an objective and good method to characterize the entire vegetation red-edge reflectance. Consequently, the proposed SIF retrieval method (hereinafter called IGMFLD) could exploit all the spectral information along the whole red-edge (680-800 nm) to obtain more reasonable reflectance and fluorescence correction coefficients than traditional FLD methods such as the iFLD. Initial results show that the IGMFLD can better capture the spectrally non-linear characterization of the reflectance in 680-800 nm and thereby yields much more accurate SIFs in O2-B than typical FLD methods, including sFLD, 3FLD and iFLD (see figure 1). Finally, uncertainties and prospect

  7. Changes in chlorophyll content and fluorescence and fruit yield contributing traits in different genotypes of strawberry (Fragaria x ananassa DUCH.

    Directory of Open Access Journals (Sweden)

    Elżbieta Kaczmarska

    2014-01-01

    Full Text Available Analysis of changes in chlorophyll fluorescence parameters in strawberry leaves was based on a field experiment performed in the years 2009–2010. Ten genotypes including 5 cultivars: ‘Kent’, ‘Teresa’, ‘Senga Sengana’, ‘Chandler’ and the breeding clone 1387 as well as their inbred progeny, were the object of the study. During the experiment the following indicators were evaluated: chlorophyll a and b content in fresh leaf mass as well as fluorescence parameters: minimum (F0 and maximum fluorescence yield (Fm, photochemical efficiency of PS II (Fv/Fm, actual quantum yield of PSII photochemistry (Y, minimum (F0’ and maximum efficiency of fluorescence (Fm’ in the light, coefficient of photochemical (qP and non-photo- chemical (qN fluorescence quenching. In this work, we also examined the effect of repeated inbreeding on strawberry fruit yield and yield components. The analysis of changes of these parameters showed that inbreeding caused a reaction in all tested cultivars. In all inbred progeny, chlorophyll a and b content decreased compared to the cultivars. Generally, the photoche- mical efficiency of photosystem II (Fv/Fm and the parameter ΔF/ Fm’ were not affected by strong inbreeding. In analyzing the values of the coefficients qP and qN, it has been observed that changes in their values depend on the sensitivity of the examined genotypes to self-pollination. The functioning of PS II is the most sensitive indicator of the effect of various factors on plants and is useful, among others, in breeding to select plants with a required genotype. The yield – determining features such as: fruit yield per plant, weight of single fruit, number of fruit per plant and weight of leaves per plant in S3 generation, were lower as compared with parental forms.

  8. The drought impact on satellite solar-induced chlorophyll fluorescence in China during 2007-2015

    Science.gov (United States)

    Li, Ruitao

    2016-04-01

    Drought is one of the most damaging and complicated natural hazards in the world. China is one of the countries which are most severely affected by drought. And there is a severe drought event in China every 2-3 years. From the beginning of the 1980s, some vegetation indices have been used to monitor vegetation under water stress. With the development of remote sensing technology, satellite solar-induced chlorophyll fluorescence (SIF) has emerged as a new method to monitor vegetation in recent years. Some studies have shown that compared with vegetation indices, SIF is more sensitive for vegetation functioning. However, the related studies using the satellite SIF is relatively limited in China. The objective of this study is to investigate the impact of drought on SIF by analyzing the relationships of SIF and crucial land surface parameter under the drought condition and to assess the adaption of satellite SIF in China. The SIF data are from the Global Ozone Monitoring Experiment 2 (GOME-2). Firstly, the widely used Palmer Drought Severity Index (PDSI) was used for drought events identification from 2007 to 2015 in China. On the basis of the identification results, we chose a number of areas of interest according to different land cover types and drought intensity. Then, we analyzed the relationships of SIF and land surface variables, i.e. normalized difference vegetation index (NDVI), the fraction of absorbed photosynthetically active radiation (fPAR), root-zone soil moisture (SMC) and surface skin temperatures (Tskin). The results show that the spatial patterns of negative SIF anomalies are closely relevant to the drought intensity. The decrease of SIF is aggravated in the phase of drought occurs. Moreover we find that the GOME-2 SIF is sensitive to fPAR and fluorescence yield. And the SIF is strongly correlated with SMC, Tskin and NDVI. But the SIF decreases more rapidly during the early time of drought events than NDVI. In other words, the SIF can well capture

  9. Monitoring the Photosynthetic Apparatus During Space Flight: Interspecific Variation in Chlorophyll Fluorescence Signatures Induced by Different Root Zone Stresses

    Science.gov (United States)

    Bubenheim, David L.; Patterson, Mark T.; Kliss, Mark H. (Technical Monitor)

    1996-01-01

    Chlorophyll fluorescence has been used extensively as a tool to indicate stress to the photosynthetic apparatus in green plants. A rise in fluorescence has been attributed to the blockage of photosystem II photochemistry, and patterns of fluorescence decay (quenching) from dark adapted leaves can be related to specific photochemical and non-photochemical deexcitation pathways of light trapped by the photosynthetic apparatus and thus result in characteristically different fluorescence signatures. Four distantly related plant species, Hypocharis radicata (Asteraceae), Brassica rapa (Brassicaceae), Spinacea oleracea (Chenopodiaceae) and Triticum aestivum (Poaceae), were grown hydroponically for three weeks before the initiation of three different root zone stresses (10 mM Cu, 100 mM NaCl and nitrogen deficient nutrition). After 10 days, characteristic fluorescence signatures for each stress could be noted although the degree varied between species. Fast kinetics analysis showed a reduction in plastoquinone pool size for copper and nitrogen stress for all species but a more species specific result with NaCl stress. Photochemical quenching kinetics varied between species and stress treatments from no quenching in S. oleracea in copper treatments to increased photochemical quenching in NaCl treatments. Non-photochemical quenching kinetics demonstrated a distinct pattern between stresses for all species. Copper treatments characteristically exhibited a shallow, flat non-photochemical quenching profile suggesting a general blockage of electron transport whereas NaCl treatments exhibited a slow rising profile that suggested damage to thylakoid acidification kinetics and nitrogen deficiency exhibited a fast rising and declining profile that suggested an altered state 1-state 2 transition regulated by the phosphorylation of LHCII. These results demonstrate characteristic fluorescence signatures for specific plant stresses that may be applied to different, unrelated plant

  10. Valinomycin sensitivity proves that light-induced thylakoid voltages result in millisecond phase of chlorophyll fluorescence transients.

    Science.gov (United States)

    Pospísil, Pavel; Dau, Holger

    2002-04-22

    Upon sudden exposure of plants to an actinic light of saturating intensity, the yield of chlorophyll fluorescence increases typically by 200-400% of the initial O-level. At least three distinct phases of these O-J-I-P transients can be resolved: O-J (0.05-5 ms), J-I (5-50 ms), and I-P (50-1000 ms). In thylakoid membranes, the J-I increase accounts for approximately 30% of the total fluorescence increase; in Photosystem II membranes, the J-I phase is always lacking. In the presence of the ionophore valinomycin, which is known to inhibit specifically the formation of membrane voltages, the magnitude of the J-I phase is clearly diminished; in the presence of valinomycin supplemented by potassium, the J-I phase is fully suppressed. We conclude that the light-driven formation of the thylakoid-membrane voltage results in an increase of the chlorophyll excited-state lifetime, a phenomenon explainable by the electric-field-induced shift of the free-energy level of the primary radical pair [Dau and Sauer, Biochim. Biophys. Acta 1102 (1992) 91]. The assignment of the J-I increase in the fluorescence yield enhances the potential of using O-J-I-P fluorescence transients for investigations on photosynthesis in intact organisms. A putative role of thylakoid voltages in protection of PSII against photoinhibitory damage is discussed. PMID:12034474

  11. Satellite chlorophyll fluorescence measurements reveal large-scale decoupling of photosynthesis and greenness dynamics in boreal evergreen forests.

    Science.gov (United States)

    Walther, Sophia; Voigt, Maximilian; Thum, Tea; Gonsamo, Alemu; Zhang, Yongguang; Köhler, Philipp; Jung, Martin; Varlagin, Andrej; Guanter, Luis

    2016-09-01

    Mid-to-high latitude forests play an important role in the terrestrial carbon cycle, but the representation of photosynthesis in boreal forests by current modelling and observational methods is still challenging. In particular, the applicability of existing satellite-based proxies of greenness to indicate photosynthetic activity is hindered by small annual changes in green biomass of the often evergreen tree population and by the confounding effects of background materials such as snow. As an alternative, satellite measurements of sun-induced chlorophyll fluorescence (SIF) can be used as a direct proxy of photosynthetic activity. In this study, the start and end of the photosynthetically active season of the main boreal forests are analysed using spaceborne SIF measurements retrieved from the GOME-2 instrument and compared to that of green biomass, proxied by vegetation indices including the Enhanced Vegetation Index (EVI) derived from MODIS data. We find that photosynthesis and greenness show a similar seasonality in deciduous forests. In high-latitude evergreen needleleaf forests, however, the length of the photosynthetically active period indicated by SIF is up to 6 weeks longer than the green biomass changing period proxied by EVI, with SIF showing a start-of-season of approximately 1 month earlier than EVI. On average, the photosynthetic spring recovery as signalled by SIF occurs as soon as air temperatures exceed the freezing point (2-3 °C) and when the snow on the ground has not yet completely melted. These findings are supported by model data of gross primary production and a number of other studies which evaluated in situ observations of CO2 fluxes, meteorology and the physiological state of the needles. Our results demonstrate the sensitivity of space-based SIF measurements to light-use efficiency of boreal forests and their potential for an unbiased detection of photosynthetic activity even under the challenging conditions interposed by evergreen

  12. The Chlorophyll a Fluorescence Modulated by All-Trans-β-Carotene in the Process of Photosystem II

    Directory of Open Access Journals (Sweden)

    Tianyu Li

    2016-06-01

    Full Text Available Modulating the chlorophyll a (Chl-a fluorescence by all-trans-β-Carotene (β-Car in the polarity and non-polarity solutions was investigated. The fluorescence intensity of Chl-a decreased as the concentration of β-Car increased. The excited electronic levels of Chl-a and β-Car became much closer owing to the solvent effect, which led to the electron transfer between both two molecules. A electron-separated pair Chl−·Chl+ that is not luminous was formed due to electron transfer. The solution of Chl-a and β-car in C3H6O was similar to the internal environment of chloroplast. We conclude that the polar solvent is good for the fluorescent modulation in photosystem II.

  13. Latent manganese deficiency in barley can be diagnosed and remediated on the basis of chlorophyll a fluorescence measurements

    DEFF Research Database (Denmark)

    Schmidt, Sidsel Birkelund; Pedas, Pai; Laursen, Kristian Holst;

    2013-01-01

    chlorophyll (Chl) a fluorescence as a tool for diagnosis of latent Mn deficiency. Methods: Barley plants grown under controlled greenhouse conditions or in the field were exposed to different intensities of Mn deficiency. The responses were characterised by analysis of Chl a fluorescence, photosystem II (PSII......) proteins and mineral elements. Results: Analysis of the Chl a fluorescence induction kinetics (FIK) revealed distinct changes long before any visual symptoms of Mn deficiency were apparent. The changes were specific for Mn and did not occur in Mg, S, Fe or Cu deficient plants. The changes in Mn deficient......Background and aims: Manganese (Mn) deficiency represents a major plant nutritional disorder in winter cereals. The deficiency frequently occurs latently and the lack of visual symptoms prevents timely remediation and cause significant yield reductions. These problems prompted us to investigate...

  14. Comparison of sun-induced chlorophyll fluorescence estimates from commercial spectroradiometers: an optimal setup for field measurement and aerial product validation.

    Science.gov (United States)

    Celesti, Marco; Rossini, Micol; Cogliati, Sergio; Panigada, Cinzia; Tagliabue, Giulia; Fava, Francesco; Julitta, Tommaso; MacArthur, Alasdair; Colombo, Roberto

    2016-04-01

    Sun-induced chlorophyll fluorescence signal is explored as a novel remote sensing method, notable for its potential to be used as a direct indicator of photosynthetic efficiency. In the last years, there was an increasing interest of the scientific community on the remote sensing of Sun-Induced chlorophyll Fluorescence (SIF). Several SIF estimates in the far-red region have been produced from spaceborne sensors, and the future FLEX satellite mission (European Space Agency, Earth-Explorer 8) aims to detect canopy level SIF in both red and far-red regions at global scale. In the context of FLEX calibration/validation activities, a network of ground station to calibrate/validate SIF estimates from space can be considered crucial, but few studies have proposed optimal technical requirements for commercially available spectroradiometers. At canopy level, SIF is traditionally retrieved from incoming and upwelling radiance measurements, exploiting two narrow oxygen absorption bands, within the O2-B and O2-A spectral regions. Only recently, the feasibility of retrieving the SIF spectrum was demonstrated. The rationale behind the exploitation of narrow spectral regions, characterized by strong absorptions, resides in the higher contribution of SIF with respect to the reflected radiance. In order to detect the signal in those narrow spectral regions, high spectral resolution observation is needed. In this study, we compared several high resolution field spectroradiometers with different Full Width at Half Maximum (FWHM), Spectral Sampling Interval (SSI) and Signal-to-Noise Ratio (SNR), to evaluate their performance in SIF estimates. We applied several state-of-the-art, radiance-based retrieval algorithms to radiance measurements taken with the FluoWAT. This device allows to measure leaf reflected and transmitted radiance, solar incident radiance and, upward and downward leaf fluorescence spectrum by means of a low pass filter, that were used as a reference.. Results show

  15. Diurnal and Directional Responses of Chlorophyll Fluorescence and the PRI in a Cornfield

    Science.gov (United States)

    Middleton, Elizabeth; Cheng, Y. B.; Corp, L.; Campbell, P.; Kustas, W.

    2010-01-01

    Determining the health and vigor of vegetation using high spectral resolution remote sensing is an important goal which has application to monitoring agriculture and ecosystem productivity and carbon exchange. Two spectral indices used to assess whether vegetation is performing near-optimally or exhibiting symptoms of environmental stress (e.g., drought or nutrient deficiency, non-optimal temperatures, etc.) are the Photochemical Reflectance Index (PRI) and solar-induced red and far-red Chlorophyll Fluorescence (Fs). Both the PRI and Fs capture the dynamics of photoprotection mechanisms within green foliage: the PRI is based on the association of the reflected radiation in the green spectrum with the xanthophyll cycle, whereas Fs measures the emitted radiation in the red and far-red spectrum. Fs was determined from retrievals in the atmospheric oxygen absorption features centered at 688 and 760 nm using a modified Fraunhofer Line Depth (FLD) method. We previously demonstrated diurnal and seasonal PRI differences for sunlit vs. shaded foliage in a conifer forest canopy, as expressed in the hotspot and darkspot of the Bidirectional Reflectance Function (BRF). In a USDA-ARS experimental field site located in Beltsville, MD, USA, measurements were acquired over a corn crop from a nadir view in 2008 with an ASD FieldSpec Pro (Analytical Spectral Devices, Inc., Boulder, CO, USA) to study the behavior of the PRI for sunlit and shaded foliage as captured in reflectance variations associated with the BRF, in a I m tall canopy in the vegetative growth stage. Those observations were compared to simulations obtained from two radiative transfer models. Measurements were then acquired to examine whether the PRI and Fs were influenced by view zenith and azimuth geometries at different times of day. Those measurements were made in 2010 with the Ocean Optics USB4000 Miniature Fiber Optic Spectrometer (Ocean Optics Inc., Dunedin, Florida, USA) at several times during the day on

  16. Effects of ozone exposure or fungal pathogen on white lupin leaves as determined by imaging of chlorophyll a fluorescence.

    Science.gov (United States)

    Guidi, Lucia; Mori, Sauro; Degl'Innocenti, Elena; Pecchia, Susanna

    2007-01-01

    Chlorophyll fluorescence has been used routinely to investigate photosynthetic activity in plants subjected to both biotic and abiotic stresses. The aim of this work was to compare the perturbations in photosynthesis induced by ozone and by a pathogen. By using a conventional fluorometer a similar response pattern was observed in inoculated and O(3)-fumigated leaves. The application of chlorophyll fluorescence imaging provided further detailed information on the spatial-temporal heterogeneity of the response of white lupin leaves to fungal pathogen or to ozone fumigation. In particular, 48 h after artificial inoculation with the necrotrophic fungal pathogen Pleiochaeta setosa, the leaves showed a remarkable alteration in PSII operating efficiency (Phi(PSII)), which affected the whole surface. Afterwards, the infection site was surrounded by a ring of increased photosynthetic activity. The response of ozonated leaves was quite different. The reduction in Phi(PSII) was already evident 24h after fumigation; moreover, a distinct heterogeneity of the fluorescence yield was observed and the major veins displayed a lowered Phi(PSII). PMID:17900916

  17. Freezing injury in cold-acclimated and unhardened spinach leaves : II. Effects of freezing on chlorophyll fluorescence and light scattering reactions.

    Science.gov (United States)

    Klosson, R J; Krause, G H

    1981-04-01

    Leaves from cold-acclimated and from unhardened spinach plants (Spinacia oleracea L.) were subjected to a freezing/thawing procedure in which varying minimum temperatures were reached. Subsequently, the chlorophyll fluorescence induction signal (Kautsky phenomenon) and the light-induced apparent absorbance changes at 535 nm (light-scattering changes indicative of the proton gradient, and absorbance changes induced by the membrane potential) of the leaves were studied to obtain information on the course and mechanism of frost damage to the photosynthetic apparatus. Membrane energization as indicated by these signals was related in a complex way to the inactivation of CO2 assimilation due to the progressing impact of freezing: In the absence of CO2, the maximum energization of the thylakoids was progressively decreased. According to altered fluorescence signals, the electron transport system was affected in parallel. In the presence of CO2, energization frequently appeared increased when the leaves had been partially damaged, i.e., when the CO2 assimilation rates were lowered. The results suggest that the primary frost injury in chloroplasts of intact leaves consists of an inhibition of the energy conserving photosynthetic processes and, in addition, of a partial inactivation of the carbon reduction cycle. The pattern of freezing injury was no different in frost-hardened and unhardened leaves. PMID:24301977

  18. Time sequence of the damage to the acceptor and donor sides of photosystem II by UV-B radiation as evaluated by chlorophyll a fluorescence

    NARCIS (Netherlands)

    Rensen, van J.J.S.; Vredenberg, W.J.; Rodrigues, G.C.

    2007-01-01

    The effects of ultraviolet-B (UV-B) radiation on photosystem II (PS II) were studied in leaves of Chenopodium album. After the treatment with UV-B the damage was estimated using chlorophyll a fluorescence techniques. Measurements of modulated fluorescence using a pulse amplitude modulated fluoromete

  19. Leaf gas exchange and chlorophyll a fluorescence in wheat plants supplied with silicon and infected with Pyricularia oryzae.

    Science.gov (United States)

    Perez, Carlos Eduardo Aucique; Rodrigues, Fabrício Ávila; Moreira, Wiler Ribas; DaMatta, Fábio Murilo

    2014-02-01

    This study investigated the effect of silicon (Si) on the photosynthetic gas exchange parameters (net CO2 assimilation rate [A], stomatal conductance to water vapor [gs], internal CO2 concentration [Ci], and transpiration rate [E]) and chlorophyll fluorescence a parameters (maximum quantum quenching [Fv/Fm and Fv'/Fm'], photochemical [qP] and nonphotochemical [NPQ] quenching coefficients, and electron transport rate [ETR]) in wheat plants grown in a nutrient solution containing 0 mM (-Si) or 2 mM (+Si) Si and noninoculated or inoculated with Pyricularia oryzae. Blast severity decreased due to higher foliar Si concentration. For the inoculated +Si plants, A, gs, and E were significantly higher in contrast to the inoculated -Si plants. For the inoculated +Si plants, significant differences of Fv/Fm between the -Si and +Si plants occurred at 48, 96, and 120 h after inoculation (hai) and at 72, 96, and 120 hai for Fv'/Fm'. The Fv/Fm and Fv'/Fm', in addition to total chlorophyll concentration (a + b) and the chlorophyll a/b ratio, significantly decreased in the -Si plants compared with the +Si plants. Significant differences between the -Si and +Si inoculated plants occurred for qP, NPQ, and ETR. The supply of Si contributed to decrease blast severity in addition to improving gas exchange performance and causing less dysfunction at the photochemical level. PMID:24047250

  20. Gas Exchange, Chlorophyll Fluorescence and Antioxidants as Bioindicators of Airborne Heavy Metal Pollution in Jeddah, Saudi Arabia

    Directory of Open Access Journals (Sweden)

    I.A. Hassan

    2013-08-01

    Full Text Available Lettuce (Lactuca sativa L. cv. Romaine plants were exposed to different levels of urbanization in Jeddah city, Saudi Arabia. They showed different degrees of visible injury symptoms and dramatic changes in enzymatic activities as well as net photosynthetic rates (PN, variable to maximum chlorophyll fluorescence (Fv/Fm and stomatal conductance (gs.Visual symptoms of phytotoxicity of heavy metals were observed on plants grown at industrial and urban areas, where the concentrations of metals was about 36 times higher than in other sites. The decrease in chlorophyll reached 70 and 64% in plants cultivated in the industrial and urban regions, while lengths of shoots reduced by 50 and 41% in plants collected from the same locations, respectively. The reduction in chlorophyll and other physiological and biochemical parameters were correlated with the concentrations of airborne pollutants measured in the atmosphere of the locations examined. Moreover, lettuce plants cultivated in the industrial region accumulated more heavy metals than others, which can pass into the human food chain.Photosynthetic efficiency was significantly decreased and lipid peroxidation was enhanced. Antioxidant enzymes were significantly altered during exposure.The biochemical and physiological parameters measured in the present study clearly showed that they could form the basis of a plant biomarkers battery for monitoring and predicting early effects of exposure to airborne heavy metals.

  1. Comparison of chlorophyll in the Red Sea derived from MODIS-Aqua and in vivo fluorescence

    KAUST Repository

    Brewin, Robert J W

    2013-09-01

    The Red Sea is a unique marine environment but relatively unexplored. The only available long-term biological dataset at large spatial and temporal scales is remotely-sensed chlorophyll observations (an index of phytoplankton biomass) derived using satellite measurements of ocean colour. Yet such observations have rarely been compared with in situ data in the Red Sea. In this paper, satellite chlorophyll estimates in the Red Sea from the MODIS instrument onboard the Aqua satellite are compared with three recent cruises of in vivo fluorometric chlorophyll measurements taken in October 2008, March 2010 and September to October 2011. The performance of the standard NASA chlorophyll algorithm, and that of a new band-difference algorithm, is found to be comparable with other oligotrophic regions in the global ocean, supporting the use of satellite ocean colour in the Red Sea. However, given the unique environmental conditions of the study area, regional algorithms are likely to fare better and this is demonstrated through a simple adjustment to the band-difference algorithm. © 2013 Elsevier Inc.

  2. High temperature stress monitoring and detection using chlorophyll a fluorescence and infrared thermography in chrysanthemum (Dendranthema grandiflora)

    DEFF Research Database (Denmark)

    Wakjera, Eshetu Janka; Körner, Oliver; Rosenqvist, Eva;

    2013-01-01

    high temperature affects the plant photosynthetic responses, resulting in a lower rate of photosynthesis. To predict and analyse physiological responses as stress indicators, two independent experiments were conducted, to detect the effect of high temperature on photosynthesis: analysing photosystem II...... (PSII) and stomatal conductance (gs). A combination of chlorophyll a fluorescence, gas exchange measurements and infrared thermography was applied using Chrysanthemum (Dendranthema grandiflora Tzvelev) ‘Coral Charm’ as a model species. Increasing temperature had a highly significant effect on PSII when...... the temperature exceeded 38 °C for a period of 7 (±1.8) days. High temperature decreased the maximum photochemical efficiency of PSII (Fv/Fm), the conformation term for primary photochemistry (Fv/Fo) and performance index (PI), as well as increased minimal fluorescence (Fo). However, at elevated CO2 of 1000 μmol...

  3. Genotypic response of detached leaves versus intact plants for chlorophyll fluorescence parameters under high temperature stress in wheat

    DEFF Research Database (Denmark)

    Sharma, Dew Kumari; Fernández, Juan Olivares; Rosenqvist, Eva;

    2014-01-01

    The genotypic response of wheat cultivars as affected by two methods of heat stress treatment (treatment of intact plants in growth chambers versus treatment of detached leaves in test tubes) in a temperature controlled water bath were compared to investigate how such different methods of heat...... treatment affect chlorophyll fluorescence parameters. A set of 41 spring wheat cultivars differing in their maximum photochemical efficiency of photosystem (PS) II (Fv/Fm) under heat stress conditions was used. These cultivars were previously evaluated based on the heat treatment of intact plants...... the fluorescence parameters. In contrast, heat induced reduction in the maximum photochemical efficiency of PSII of detached leaves occurred within 2h at 40°C and within 30min at 45°C, and the response was more pronounced than when intact plants were heat stressed for three days at 40°C. The proportion of total...

  4. Effects of water stress and light intensity on chlorophyll fluorescence parameters and pigments of Aloe vera L.

    Science.gov (United States)

    Hazrati, Saeid; Tahmasebi-Sarvestani, Zeinolabedin; Modarres-Sanavy, Seyed Ali Mohammad; Mokhtassi-Bidgoli, Ali; Nicola, Silvana

    2016-09-01

    Aloe vera L. is one of the most important medicinal plants in the world. In order to determine the effects of light intensity and water deficit stress on chlorophyll (Chl) fluorescence and pigments of A. vera, a split-plot in time experiment was laid out in a randomized complete block design with four replications in a research greenhouse. The factorial combination of three light intensities (50, 75 and 100% of sunlight) and four irrigation regimes (irrigation after depleting 20, 40, 60 and 80% of soil water content) were considered as main factors. Sampling time was considered as sub factor. The first, second and third samplings were performed 90, 180 and 270 days after imposing the treatments, respectively. The results demonstrated that the highest light intensity and the severe water stress decreased maximum fluorescence (Fm), variable fluorescence (Fv)/Fm, quantum yield of PSII photochemistry (ФPSII), Chl and photochemical quenching (qP) but increased non-photochemical quenching (NPQ), minimum fluorescence (F0) and Anthocyanin (Anth). Additionally, the highest Fm, Fv/Fm, ФPSII and qP and the lowest NPQ and F0 were observed when 50% of sunlight was blocked and irrigation was done after 40% soil water depletion. Irradiance of full sunlight and water deficit stress let to the photoinhibition of photosynthesis, as indicated by a reduced quantum yield of PSII, ФPSII, and qP, as well as higher NPQ. Thus, chlorophyll florescence measurements provide valuable physiological data. Close to half of total solar radiation and irrigation after depleting 40% of soil water content were selected as the most efficient treatments. PMID:27161580

  5. Lhcb transcription is coordinated with cell size and chlorophyll accumulation. Studies on fluorescence-activated, cell-sorter-purified single cells from wild-type and immutans Arabidopsis thaliana

    Energy Technology Data Exchange (ETDEWEB)

    Meehan, L.; Harkins, K.; Rodermel, S. [Iowa State Univ., Ames, IA (United States)] [and others

    1996-11-01

    To study the mechanisms that integrate pigment and chlorophyll a/b-binding apoprotein biosynthesis during light-harvesting complex II assembly, we have examined {beta}-glucuronidase (GUS) enzyme activities, cell-sorting-separated single cells sizes in fluorescence activated, cell-sorting-separated single cells from transgenic Arabidopsis thaliana wild-type and immutans variegation mutant plants that express an Lhcb (photosystem II chlorophyll a/b-binding polypeptide gene)/GUS promoter fusion. We found that GUS activities are positively correlated with chlorophyll content and cell size in green cells from the control and immutans plants, indicating that Lhcb gene transcription is coordinated with cell size in this species. Compared with the control plants, however, chlorophyll production is enhanced in the green cells of immutans; this may represent part of a strategy to maximize photosynthesis in the white sectors of the mutant. Lhcb transcription is significantly higher in pure-white cells of the transgenic immutans plants than in pure-white cells from norflurazon-treated, photooxidized A. thaliana leaves. This suggests that immutans partially uncouples Lhcb transcription from its normal dependence on chlorophyll accumulation and chloroplast development. We conclude that immutans may play a role in regulating Lhcb transcription, and may be a key component in the signal transduction pathways that control chloroplast biogenesis. 58 refs., 5 figs., 2 tabs.

  6. Improvement of Photosynthesis by Sub1 QTL in Rice Under Submergence: Probed by Chlorophyll Fluorescence OJIP Transients

    Directory of Open Access Journals (Sweden)

    Panda Debabrata

    2011-09-01

    Full Text Available The influence of submergence on the photosynthetic activity in rice plants either possessing or not possessing Sub1 QTL i.e. Swarna and Swarna Sub1 cultivars (cv. were evaluated under simulated complete submergence. The leaf photosynthetic rate and stomatal conductance decreased in both the cv. during the progression of submergence as compared to control plant but significant varietal differences was observed after 1 day (d of submergence. Submergence also alters the photo-system (PS II activity, as reflected in a decrease in the values of Fo, Fm and the Fv/Fm ratio and degradation of chlorophyll, more in Swarna than that of Swarna Sub1. Under complete submergence the shape of the OJIP transient also changed in rice leaves with decrease in maximal fluorescence (P=Fm intensity, resulted lowering of variable fluorescence levels. The decrease was more pronounced in Swarna compared to the Swarna Sub1 cv. Thus, Swarna Sub1 improves photosynthetic activity showing more photosynthetic rate compared to Swarna under submergence because, of less degradation of chlorophyll, higher stomatal conductance, and efficient PS II activity.

  7. Effects of Nitrogen Fertilizer Level on Chlorophyll Fluorescence Characteristics in Flag Leaf of Super Hybrid Rice at Late Growth Stage

    Institute of Scientific and Technical Information of China (English)

    LONG Ji-rui; MA Guo-hui; WAN Yi-zheng; SONG Chun-fang; SUN Jian; QIN Rui-jun

    2013-01-01

    To compare the effects of slow-release nitrogen fertilizer at six different levels on the flag leaf chlorophyll fluorescence characteristics of super hybrid rice,a field fertilization experiment was conducted with super hybrid rice Y Liangyou 1 as a test material.The photosynthetic electron transport rate (ETR),effective quantum yield (EQY),photochemical quenching coefficient (qp),and non-photochemical quenching coefficient (NPQ) of flag leaves were measured at the initial heading,full heading,10 d after full heading and 20 d after full heading stages.Results showed that the values of ETR,EQY and qp increased with rice development from initial heading to 20 d after full heading,whereas the NPQ decreased.During the measured stages,ETR,EQY and qp increased initially and then decreased as nitrogen application amount increased,but they peaked at different nitrogen fertilizer levels.The maximum ETR and EQY values appeared at the treatment of 135 kg/hm2 N.In conclusion,the optimum nitrogen amount for chlorophyll fluorescence characteristics of super hybrid rice was 135-180 kg/hm2.

  8. Dissection of respiration and photosynthesis in the cyanobacterium Synechocystis sp. PCC6803 by the analysis of chlorophyll fluorescence.

    Science.gov (United States)

    Ogawa, Takako; Sonoike, Kintake

    2015-03-01

    In cyanobacteria, photosynthesis and respiration share some components of electron transport chain. To explore the interaction between photosynthesis and respiration, we monitored the change in the yield of chlorophyll fluorescence due to state transition in ndh genes disruptants, deficient in NAD(P)H dehydrogenase (NDH-1) complexes serving for respiration or for carbon concentrating mechanism (CCM). The disruption of ndh genes essential for respiration resulted in low levels of chlorophyll fluorescence quenching in the dark (NPQDark) as well as in the low light (NPQLL). The lowered NPQDark and NPQLL in these ndh genes disruptants could be ascribed to the oxidation of the PQ pool due to the poor electron supply from NDH-1 complexes in respiratory electron transport. On the other hand, only NPQLL decreased upon disruption of the ndh genes essential for CCM. We propose that, in the disruptants of these ndh genes, the PQ pool is oxidized in the light through the increased photosystem I content, resulting in the lowered NPQLL. Apparently, the two different subsets of ndh genes affect photosynthetic electron transport although in totally different manners. It is also suggested that monitoring state transition is a simple method to evaluate the condition of photosynthesis, respiration and CCM. PMID:25723341

  9. Multiple effects of cadmium on the photosynthetic apparatus of Avicennia germinans L. as probed by OJIP chlorophyll fluorescence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gonzales-Mendoza, D.; Zapata-Perez, O. [Cinvestav Unidad Merida, Yucatan (Mexico). Dept. de Recursos del Mar; Espadas y Gil, F.; Santamaria, J.M. [Unidad de Biotecnologia, CICY, Yucatan (Mexico)

    2007-03-15

    The toxic effects of cadmium on the photosynthetic apparatus of Avicennia germinans were evaluated by means of the chlorophyll fluorescence transient O-J-I-P. The chlorophyll fluorescence transients were recorded in vivo with high time resolution and analyzed according to the OJIP-test that can quantify the performance of photosystem II. Cadmium-treated plants showed a decrease in yield for primary photochemistry, TR{sup 0}/ABS. The performance index of photosystem II (PSII), PI{sub ABS}, decreased due to cadmium treatment. This performance index is the combination of the indexes of three independent parameters: (1) total number of active reaction centers per absorption (RC/ABS), (2) yield of primary photochemistry (TR{sup 0}/ABS), and (3) efficiency with which a trapped exciton can move an electron into the electron transport chain (ET{sup 0}/TR{sup 0}). Additionally, the F{sub 0}/F{sub v} registered the highest sensitivity to the metal, thus indicating that the water-splitting apparatus of the oxidizing side of PSII is the primary site of action of cadmium. In summary, cadmium affects several targets of photosystem II. More specifically the main targets of cadmium, according to the OJIP-test, can be listed as a decrease in the number of active reaction centers and damage to the activity of the water-splitting complex. (orig.)

  10. Screening for Barley Waterlogging Tolerance in Nordic Barley Cultivars (Hordeum vulgare L. Using Chlorophyll Fluorescence on Hydroponically-Grown Plants

    Directory of Open Access Journals (Sweden)

    Nils-Ove Bertholdsson

    2013-04-01

    Full Text Available Waterlogging can reduce crop yield by 20%–50% or more, and lack of efficient selection methods is an obstacle in plant breeding. The methods currently used are mainly indices based on germination ability in Petri dishes and leaf chlorosis in plants grown in waterlogged soils. Cultivation in oxygen-depleted nutrient solution is the ultimate waterlogging system. Therefore methods based on root growth inhibition and on fluorescence in plant material hydroponically grown in oxygen-depleted solution were evaluated against data on biomass accumulation in waterlogged soils. Both traits were correlated with waterlogging tolerance in soil, but since it was easier to measure fluorescence, this method was further evaluated. A selection of F2 plants with high and low fluorescence revealed a small but significant screening effect in F3 plants. A test of 175 Nordic cultivars showed large variations in chlorophyll fluorescence in leaves from oxygen-stressed seedlings, indicating that adaptation to waterlogging has gradually improved over the past 40–50 years with the introduction of new cultivars onto the market. However, precipitation also increased during the period and new cultivars may have inadvertently been adapted to this while breeding barley for grain yield. The results suggest that the hydroponic method can be used for screening barley populations, breeding lines or phenotyping of populations in developing markers for quantitative trait loci.

  11. Chlorophyll a Covalently Bonded to Organo-Modified Translucent Silica Xerogels: Optimizing Fluorescence and Maximum Loading

    OpenAIRE

    García-Sánchez, M. A.; I. N. Serratos; R. Sosa; T. Tapia-Esquivel; F. González-García; F. Rojas-González; S. R. Tello-Solís; A. Y. Palacios-Enriquez; J. M. Esparza Schulz; A. Arrieta

    2016-01-01

    Chlorophyll is a pyrrolic pigment with important optical properties, which is the reason it has been studied for many years. Recently, interest has been rising with respect to this molecule because of its outstanding physicochemical properties, particularly applicable to the design and development of luminescent materials, hybrid sensor systems, and photodynamic therapy devices for the treatment of cancer cells and bacteria. More recently, our research group has been finding evidence for the ...

  12. Soils as environmental fluorescence database to explain the speleothem fluorescence signal.

    Science.gov (United States)

    Quiers, Marine; Perrette, Yves; Poulenard, Jérôme; Chalmin, Emilie; Revol, Morgane

    2014-05-01

    In this study, we propose to use soils water-extracted organic matter (OM) as a database of fluorescence signal, to interpret quantitatively the the fluorescence of speleothems OM. Due to its efficiency to described dissolved organic matter (DOM) characteritics, fluorescence has been used to determined DOM signatures in natural systems, water circulations, OM transfer from soils, OM evolution in soils or recently, DOM changes in engineered treatment systems. Fluorescence has also been used in speleothems studies, mainly as a growth indicator. Only few studies interpret it as an environmental proxy. Speleothem fluorescence can be used as an environmental proxy, to record the past soil evolutions. Qualitative changes of OM are easily measured. However, it's today complicated to quantify the fluorescence signal of speleothems due to the analytical method generally used. That's why we propose to interpret quantitatively the fluorescence signal of speleothems, using soil fluorescence as a database of fluorescence signal. 3 different samples of stalagmites from french northern Prealps were used. To allow the quantification of the fluorescence signal, we need to measure the fluorescence and the quantity of organic matter on the same sample. OM of speleothems was extracted by an acid digestion method and analysed with a spectrofluorimeter. However, it was not possible to quantify directly the OM, as the extract solvant was a high-concentrated acid. To solve this problem, a calibration using soil extracts was realised. Soils were chosen in order to represent the diversity of OM present in the environment above the caves. Attention was focused on soil and vegetation types, and landuse. Organic material was water extracted from soils and its fluorescence was also measured. Total organic carbon was performed on the same samples. This allow to compare the two fluorescence signals. A range of OM concentrations can be then attributed to the speleothem signal. Fluorescence

  13. Detection of microcystin contamination by the measurement of the variability of the in vivo chlorophyll fluorescence in aquatic plant Lemna gibba.

    Science.gov (United States)

    Saqrane, S; El Ghazali, I; Oudra, B; Bouarab, L; Dekayir, S; Mandi, L; Ouazzani, N; Vasconcelos, V M

    2009-01-01

    In recent years, chlorophyll fluorescence analysis has become one of the most powerful and widely used techniques available to plant ecophysiologists. In this work, the chlorophyll fluorescence is used in order to evaluate the biotic stress induced by exposure to cyanobacterial toxins (microcystins). Experiments were carried on the aquatic plant Lemna gibba exposed to various concentrations of a microcystins (0.01, 0.03, 0.05, 0.07, 0.15, 0.22 and 0.3mug equivalent MC-LR.mL(-1)) during 5h. The reversibility of the stress changes was also studied following 24h of treatment. The efficiency and the utility of this biophysical technique were compared to biochemical analysis priory used to evaluate the plant stress induced by such contamination. The results showed that there is a concentration-dependent effect on the measured in vivo chlorophyll fluorescence with significant differences between the control and all concentrations except for 0.01mug equivalent MC-LR.mL(-1). The reversibility tested showed also that after avoiding the contact with the microcystins, the chlorophyll fluorescence measurements were not significantly different from the control. The results showed that if the contact with the microcystins is short and not repeated plants may not suffer from a significant stress. We concluded that this simple and rapid technique based on the variable fluorescence, could be recommended and applied to test the plant stress caused by cyanobacterial toxins. PMID:18977237

  14. The Seasonal Cycle of Satellite Chlorophyll Fluorescence Observations and its Relationship to Vegetation Phenology and Ecosystem Atmosphere Carbon Exchange

    Science.gov (United States)

    Joiner, J.; Yoshida, Y.; Vasilkov, A. P.; Schaefer, K.; Jung, M.; Guanter, L.; Zhang, Y; Garrity, S.; Middleton, E. M.; Huemmrich, K. F.; Gu, L.; Marchesini, L. Belelli

    2014-01-01

    Mapping of terrestrial chlorophyll uorescence from space has shown potentialfor providing global measurements related to gross primary productivity(GPP). In particular, space-based fluorescence may provide information onthe length of the carbon uptake period that can be of use for global carboncycle modeling. Here, we examine the seasonal cycle of photosynthesis asestimated from satellite fluorescence retrievals at wavelengths surroundingthe 740nm emission feature. These retrievals are from the Global OzoneMonitoring Experiment 2 (GOME-2) flying on the MetOp A satellite. Wecompare the fluorescence seasonal cycle with that of GPP as estimated froma diverse set of North American tower gas exchange measurements. Because the GOME-2 has a large ground footprint (40 x 80km2) as compared with that of the flux towers and requires averaging to reduce random errors, we additionally compare with seasonal cycles of upscaled GPP in the satellite averaging area surrounding the tower locations estimated from the Max Planck Institute for Biogeochemistry (MPI-BGC) machine learning algorithm. We also examine the seasonality of absorbed photosynthetically-active radiation(APAR) derived with reflectances from the MODerate-resolution Imaging Spectroradiometer (MODIS). Finally, we examine seasonal cycles of GPP as produced from an ensemble of vegetation models. Several of the data-driven models rely on satellite reflectance-based vegetation parameters to derive estimates of APAR that are used to compute GPP. For forested sites(particularly deciduous broadleaf and mixed forests), the GOME-2 fluorescence captures the spring onset and autumn shutoff of photosynthesis as delineated by the tower-based GPP estimates. In contrast, the reflectance-based indicators and many of the models tend to overestimate the length of the photosynthetically-active period for these and other biomes as has been noted previously in the literature. Satellite fluorescence measurements therefore show potential for

  15. Glyphosate effects on gas exchange and chlorophyll fluorescence responses of two Lolium perenne L. biotypes with differential herbicide sensitivity.

    Science.gov (United States)

    Yanniccari, Marcos; Tambussi, Eduardo; Istilart, Carolina; Castro, Ana María

    2012-08-01

    Despite the extensive use of glyphosate, how it alters the physiology and metabolism of plants is still unclear. Photosynthesis is not regarded to be a primary inhibitory target of glyphosate, but it has been reported to be affected by this herbicide. The aim of the current research was to determine the effects of glyphosate on the light and dark reactions of photosynthesis by comparing glyphosate-susceptible and glyphosate-resistant Lolium perenne biotypes. After glyphosate treatment, accumulation of reduced carbohydrates occurred before a decrease in gas exchange. Stomatal conductance and CO(2) assimilation were reduced earlier than chlorophyll fluorescence and the amount of chlorophyll in susceptible plants. In the glyphosate-resistant biotype, stomatal conductance was the only parameter slightly affected only 5 days post-application. In susceptible plants, the initial glyphosate effects on gas exchange could be a response to a feedback regulation of photosynthesis. Since the herbicide affects actively growing tissues regardless of the inhibition of photosynthesis, the demand of assimilates decreased and consequently induced an accumulation of carbohydrates in leaves. We concluded that stomatal conductance could be a very sensitive parameter to assess both the susceptibility/resistance to glyphosate before the phytotoxic symptoms become evident.

  16. Experimental effects of sand-dust storm on tolerance index, percentage phototoxicity and chlorophyll a fluorescence of Vigna radiata L.

    Directory of Open Access Journals (Sweden)

    M. Alavi

    2015-03-01

    Full Text Available In arid and semi-arid parts of the world excessive mineral aerosol carried by air parcels is a common climatic incident with well-known environmental side effects. In this way, we studied the role of sand-dust accumulation on various aspects of productivity of Vigna radiata L. including dry mass (DM, chlorophyll (Chl a, b, Chlorophyll a fluorescence (effective quantum yield of PSII photochemistry (ФPSII, maximal quantum yield of PSII photochemistry (Fv/Fm and electron transport rate (ETR. V. radiata was exposed to a gradient of dust concentrations in a dust chamber (0.5 (T1, 1(T2 and 1.5 g/m3 (T3 simulated by a dust generator for a period of 60 days. Results of this experiment indicate that DM and Chl content of shoot are negatively correlated with the intensity of the dust exposure. Exposure of V. radiata to dust compared with the control was caused 5% (T1, 14% (T2 and 27% (T3 reduction in leaf DM (p≤0.05, ANOVA. Also, exposure to the dust induced a significant (p≤0.05 reduction in the Total Chl content in (T3 25%. Also, we showed that ФPSII, ETR and Fv/Fm were affected by increasing of the dust concentrations. Exposure to the dust resulted in a significant reduction in ETR of 15%, 22%, and 43%.

  17. Effects of sand burial on biomass, chlorophyll fluorescence and extracellular polysaccharides of man-made cyanobacterial crusts under experimental conditions

    Institute of Scientific and Technical Information of China (English)

    WANG WeiBo; YANG CuiYun; TANG DongShan; LI DunHai; LIU YongDing; HU ChunXiang

    2007-01-01

    Soil cyanobacterial crusts occur throughout the world, especially in the semiarid and arid regions. It always encounters sand burial, which is an important feature of mobile sand dunes. A greenhouse study was conducted to determine the effects of sand burial on biomass, chlorophyll fluorescence andextracellular polysaccharides of man-made cyanobacterial crusts in six periods of time (0, 5, 10, 15, 20 and 30 d after burying) and at five depths (0, 0.2, 0.5, 1 and 2cm). The results indicated that with the increase of the burial time and burial depth extracellular polysaccharides content and Fv/Fm decreased correspondingly and there were no significant differences between 20 and 30 burial days under different burial depths. The degradation of chlorophyll a content appeared only at 20 and 30 burial days and there was also no significant difference between them under different burial depths. It was also observed a simultaneous decrease of the values of the Fv/Fm and the content of extracellular polysaccharides happened in the crusted cyanobacterium Microcoleus vaginatus Gom. It may suggest that there exists a relationship between extracellular polysaccharides and recovery of the activity of photosystem Ⅱ (PS Ⅱ) after rehydration.

  18. The 2010 Russian Drought Impact on Satellite Measurements of Solar-Induced Chlorophyll Fluorescence: Insights from Modeling and Comparisons with the Normalized Differential Vegetation Index (NDVI)

    Science.gov (United States)

    Yoshida, Y.; Joiner, J.; Tucker, C.; Berry, J.; Lee, J. -E.; Walker, G.; Reichle, R.; Koster, R.; Lyapustin, A.; Wang, Y.

    2015-01-01

    We examine satellite-based measurements of chlorophyll solar-induced fluorescence (SIF) over the region impacted by the Russian drought and heat wave of 2010. Like the popular Normalized Difference Vegetation Index (NDVI) that has been used for decades to measure photosynthetic capacity, SIF measurements are sensitive to the fraction of absorbed photosynthetically-active radiation (fPAR). However, in addition, SIF is sensitive to the fluorescence yield that is related to the photosynthetic yield. Both SIF and NDVI from satellite data show drought-related declines early in the growing season in 2010 as compared to other years between 2007 and 2013 for areas dominated by crops and grasslands. This suggests an early manifestation of the dry conditions on fPAR. We also simulated SIF using a global land surface model driven by observation-based meteorological fields. The model provides a reasonable simulation of the drought and heat impacts on SIF in terms of the timing and spatial extents of anomalies, but there are some differences between modeled and observed SIF. The model may potentially be improved through data assimilation or parameter estimation using satellite observations of SIF (as well as NDVI). The model simulations also offer the opportunity to examine separately the different components of the SIF signal and relationships with Gross Primary Productivity (GPP).

  19. Effect of Light Quality on Photosynthesis and Chlorophyll Fluorescence in Strawberry Leaves

    Institute of Scientific and Technical Information of China (English)

    XU Kai; GUO Yan-ping; ZHANG Shang-long; ZHANG Liang-cheng; ZHANG Ling-xiao

    2004-01-01

    The photosynthetic characteristics of strawberry(Fragaria x ananassa Duch. cv. Toyonoka)leaves under illumination of identical light intensity(55-57% natural light)with different light quality were studied. It was showed that the chlorophyll content,maximal photochemical efficiency of PS Ⅱ(Fv/Fm),Fm/Fo,amount of inactive PS Ⅱ reaction centers(Fi-Fo)and rate of QAreduction were positively correlated with the red-light/blue-light ratios,but the chlorophyll(a/b)ratios were negatively correlated with them. Carotenoid content of the leaves was maximum under the blue film,than under green film,red film,white film and yellow film,and negatively correlated with the red/farred ratios. The apparent quantum yield(AQY),photorespiratory rate(Pr)and carboxylation efficiency(CE)were also strongly affected by light quality. The photosynthetic rate(Pn)in strawberry leaves under green film was significantly lower than under all other film. Our results suggested that light quality is an essential factor regulating the development of PS Ⅱ and phytochrome and an independent blue light photoreceptor,possibly a cryptochrome,can regulate photosynthetic performance.

  20. [Extraction and analysis of solar-induced chlorophyll fluorescence of wheat with ground-based hyperspectral imaging system].

    Science.gov (United States)

    Wang, Ran; Liu, Zhi-gang; Feng, Hai-kuan; Yang, Pei-qi; Wang, Qing-shan; Ni, Zhuo-ya

    2013-09-01

    Dataset simulated with FluorMOD and images of wheat in heading stage taken by a ground-based hyperspectral imaging system with 3.3 nm spectral resolution and 0. 71-0. 74 nm spectral sampling interval were used test the feasibility and accuracy of three FLD methods (named FLD, 3FLD and iFLD). The results show that when spectral resolution is 3.3 nm, solar-induced chlorophyll fluorescence could be extracted effectively in O2-A band (around 760 nm) instead of O2-B band (around 687 nm). As to the extraction results of data with noises, both FLD and 3FLD are stabler than iFLD method. The results of FLD tend to be higher than true value. PMID:24369651

  1. Non-invasive measurements of leaf epidermal transmittance of UV radiation using chlorophyll fluorescence: field and laboratory studies

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, P.W. [Southwest Texas State Univ.. Dept. of Biology, San Marcos, TX (United States); Searles, P.S.; Ryel, R.J.; Caldwell, M.M. [Utah State Univ., Dept. of Rangeland Resources and the Ecology Center, Logan, UT (United States); Ballare, C.L. [IFEVA, Univ. de Buenos Aires, Dept. de Ecologia, Facultad de Agronomia, Buenos Aires, (Argentina)

    2000-07-01

    Ratios of chlorophyll fluorescence induced by ultraviolet (UV) and bluegreen (BG) radiation [F(UV)/F(BG)] were determined with a Xe-PAM fluorometer to test the utility of this technique as a means of non-intrusively assessing changes in the pigmentation and optical properties of leaves exposed to varying UV exposures under laboratory and field conditions. For plants of Vicia faba and Brassica campestris, grown under controlled-environmental conditions, F(UV-B)/F(BG) was negatively correlated with whole-leaf UV-B-absorbing pigment concentrations. Fluorescence ratios of V.faba were similar to, and positively correlated with (r{sup 2} = 0.77 [UV-B]; 0.85 [UV-A]), direct measurements of epidermal transmittance made with an integrating sphere. Leaves of 2 of 4 cultivars of field-grown Glycine max exposed to near-ambient solar UV-B at a mid-latitude site (Buenos Aires, Argentina, 34 degrees S) showed significantly lower abaxial F(UV-B)/F(BG) values (i.e., lower UV-B epidermal transmittance) than those exposed to attenuated UV-B, but solar UV-B reduction had a minimal effect on F(UV-B)/F(BG) in plants growing at a high-latitude site (Tierra del Fuego, Argentina, 55 degrees S). Similarly, the exotic Taraxacum officinale did not show significant changes in F(UV-B)/F(BG) when exposed to very high supplemental UV-B (biologically effective UV-B = 14-15 kJ m{sup -2} day{sup -1}) in the field in Tierra del Fuego, whereas a native species, Gunnera magellanica, showed significant increases in F(UV-B)/F(BG) relative to those receiving ambient UV-B. These anomalous fluorescence changes were associated with increases in BG-absorbing pigments (anthocyanins), but not UV-B-absorbing pigments. These results indicate that non-invasive estimates of epidermal transmittance of UV radiation using chlorophyll fluorescence can detect changes in pigmentation and leaf optical properties induced by UV-B radiation under both field and laboratory conditions. However, this technique may be of limited

  2. Detection of water stress in orchard trees with a high-resolution spectrometer through Chlorophyll fluorescence in-filling of the O-2-A band

    OpenAIRE

    Miller, John R.; Pérez-Priego, Óscar; Zarco-Tejada, Pablo J.; Fereres Castiel, Elías; Sepulcre-Cantó, Guadalupe

    2005-01-01

    A high spectral resolution spectrometer with 0.065-nm full-width half-maximum was used for collecting spectral measurements in an orchard field under three water stress treatments. The study was part of the FluorMOD project funded by the European Space Agency to develop a leaf-canopy reflectance model to simulate the effects of fluorescence. Water deficit protocols generated a gradient in solar-induced Chlorophyll fluorescence emission and tree physiological measures. Diurnal steady-state Chl...

  3. Response of carbon assimilation and chlorophyll fluorescence to soybean leaf phosphorus across CO2: Alternative electron sink, nutrient efficiency and critical phosphorus concentration

    Science.gov (United States)

    To evaluate the response of CO2 assimilation (PN) and various chlorophyll fluorescence (CF) parameters to phosphorus (P) nutrition soybean plants were grown in controlled environment growth chambers with sufficient (0.50 mM) and deficient (0.10 and 0.01 mM) P supply under ambient and elevated CO2 (a...

  4. Grassland species will not necessarily benefit from future elevated air temperatures. A chlorophyll fluorescence approach to study autumn physiology

    Energy Technology Data Exchange (ETDEWEB)

    Gielen, B.; Boeck, H.J. De; Lemmens, C.M.H.M.; Nijs, I.; Ceulemans, R. [Univ. of Antwerp, Dept. of Biology, Wilrijk (Belgium); Valcke, R. [Limburgs Univ. Centrum, Dept. SBG, Diepenbeek (Belgium)

    2005-09-01

    Model ecosystems were Brown in 12 sunlit, climate-controlled chambers to gain insight into the effects of elevated (+3 deg. C) air temperature (T{sub air}) on temperate grasslands. In this study, the hypothesis of delayed senescence in response to elevated T{sub air} was tested for Rumex acetosa L. and Plantago lanceolata L. During the autumn of the first treatment year, frequent measurements were made of leaf chlorophyll a (Chla) fluorescence transients. Chl fluorescence images of individual teaves as well as digital colour images of these ecosystems were captured. Chl fluorescence variables, such as the maximum quantum yield of primary photochemistry (F{sub v}/F{sub m}), indicated a decreasing efficiency with time. Despite no treatment effect on F{sub v}/F{sub m}, other variables derived from the Chl fluorescence transients showed a strong trend towards a positive effect of a 3 deg. C temperature increase on the photosynthetic performance of R. acetosa and P. lanceolata in the first year. After mid-September, the initial positive treatment effect disappeared for R. acetosa, strongly suggesting that leaf lifespan of this species was shortened by higher T{sub air}. One possibly explanation is more intense drought stress in the elevated compared to the ambient temperature treatments. Second-year measurements were possibly too limited in time to confirm this trend. These results show that temperate grassland species may take advantage of a future increase in T{sub air} during autumn. This will ultimately depend on the species' degree of acclimation to a temperature change and on the resistance to drought stress. (au)

  5. Study the effect of insecticide dimethoate on photosynthetic pigments and photosynthetic activity of pigeon pea: Laser-induced chlorophyll fluorescence spectroscopy.

    Science.gov (United States)

    Pandey, Jitendra Kumar; Dubey, Gunjan; Gopal, R

    2015-10-01

    Pigeon pea is one of the most important legume crops in India and dimethoate is a widely used insecticide in various crop plants. We studied the effect of dimethoate on growth and photosynthetic activity of pigeon pea plants over a short and long term exposure. Plant growth parameters, photosynthetic pigment content and chlorophyll fluorescence response of pigeon pea (Cajanus cajan L.) plants treated with various concentrations of the insecticide dimethoate (10, 20, 40 and 80 ppm) have been compared for 30 days at regular intervals of 10 days each. Laser induced chlorophyll fluorescence spectra and fluorescence-induction kinetics (FIK) curve of dimethoate treated pigeon pea plants were recorded after 10, 20 and 30 days of treatment. Fluorescence intensity ratio at the two fluorescence maxima (F685/F730) was calculated by evaluating curve-fitted parameters. The variable chlorophyll fluorescence decrease ratio (Rfd) was determined from the FIK curves. Our study revealed that after 10 days of treatment, 10 ppm of dimethoate showed stimulatory response whereas 20, 40 and 80 ppm of dimethoate showed inhibitory response for growth and photosynthetic activity of pigeon pea plants, but after 20 and 30 days of treatment all the tested concentrations of dimethoate became inhibitory. This study clearly shows that dimethoate is highly toxic to the pigeon pea plant, even at very low concentration (10 ppm), if used for a prolonged duration. Our study may thus be helpful in determining the optimal dose of dimethoate in agricultural practices. PMID:25228224

  6. Early fluorescence signals detect transitions at mammalian serotonin transporters.

    OpenAIRE

    Li, Ming; Lester, Henry A.

    2002-01-01

    The mammalian serotonin transporters rSERT or hSERT were expressed in oocytes and labeled with sulforhodamine-MTS. The endogenous Cys-109 residue contributes most of the signal, and the labeled transporter shows normal function. The SERT fluorescence decreases in the presence of 5-HT and also depends on the inorganic substrates of SERT. The fluorescence also increases with membrane depolarization. During voltage-jump experiments, fluorescence relaxations show little inactivation or history de...

  7. The interrelationship between the lower oxygen limit, chlorophyll fluorescence and the xanthophyll cycle in plants.

    Science.gov (United States)

    Wright, A Harrison; DeLong, John M; Gunawardena, Arunika H L A N; Prange, Robert K

    2011-03-01

    The lower oxygen limit (LOL) in plants may be identified through the measure of respiratory gases [i.e. the anaerobic compensation point (ACP) or the respiratory quotient breakpoint (RQB)], but recent work shows it may also be identified by a sudden rise in dark minimum fluorescence (F(o)). The interrelationship between aerobic respiration and fermentative metabolism, which occur in the mitochondria and cytosol, respectively, and fluorescence, which emanates from the chloroplasts, is not well documented in the literature. Using spinach (Spinacia oleracea), this study showed that F(o) and photochemical quenching (q(P)) remained relatively unchanged until O(2) levels dropped below the LOL. An over-reduction of the plastoquinone (PQ) pool is believed to increase F(o) under dark + anoxic conditions. It is proposed that excess cytosolic reductant due to inhibition of the mitochondria's cytochrome oxidase under low-O(2), may be the primary reductant source. The maximum fluorescence (F(m)) is largely unaffected by low-O(2) in the dark, but was severely quenched, mirroring changes to the xanthophyll de-epoxidation state (DEPS), under even low-intensity light (≈4 μmol m(-2) s(-1)). In low light, the low-O(2)-induced increase in F(o) was also quenched, likely by non-photochemical and photochemical means. The degree of quenching in the light was negatively correlated with the level of ethanol fermentation in the dark. A discussion detailing the possible roles of cyclic electron flow, the xanthophyll cycle, chlororespiration and a pathway we termed 'chlorofermentation' were used to interpret fluorescence phenomena of both spinach and apple (Malus domestica) over a range of atmospheric conditions under both dark and low-light. PMID:21290261

  8. Can CO2 assimilation in maize leaves be predicted accurately from chlorophyll fluorescence analysis?

    Science.gov (United States)

    Edwards, G E; Baker, N R

    1993-08-01

    Analysis is made of the energetics of CO2 fixation, the photochemical quantum requirement per CO2 fixed, and sinks for utilising reductive power in the C4 plant maize. CO2 assimilation is the primary sink for energy derived from photochemistry, whereas photorespiration and nitrogen assimilation are relatively small sinks, particularly in developed leaves. Measurement of O2 exchange by mass spectrometry and CO2 exchange by infrared gas analysis under varying levels of CO2 indicate that there is a very close relationship between the true rate of O2 evolution from PS II and the net rate of CO2 fixation. Consideration is given to measurements of the quantum yields of PS II (φ PS II) from fluorescence analysis and of CO2 assimilation ([Formula: see text]) in maize over a wide range of conditions. The[Formula: see text] ratio was found to remain reasonably constant (ca. 12) over a range of physiological conditions in developed leaves, with varying temperature, CO2 concentrations, light intensities (from 5% to 100% of full sunlight), and following photoinhibition under high light and low temperature. A simple model for predicting CO2 assimilation from fluorescence parameters is presented and evaluated. It is concluded that under a wide range of conditions fluorescence parameters can be used to predict accurately and rapidly CO2 assimilation rates in maize. PMID:24317706

  9. GAS EXCHANGE AND CHLOROPHYLL FLUORESCENCE OF CITRUS ROOTSTOCK VARIETIES UNDER SALT STRESS

    Directory of Open Access Journals (Sweden)

    MARCOS ERIC BARBOSA BRITO

    2016-01-01

    Full Text Available ABSTRACT High salt concentration in water are common in Brazilian semirad region, being important to research alternatives for use this waters on crop, like use of tolerant genotypes to salinity. Thus, in order to evaluate the saline stress perception of citrus rootstocks varieties crop from gas exchange and fluorescence analysis, an experiment was realized in greenhouse at the Center for Science and Technology Agrifood, CCTA, of Federal University of Campina Grande, UFCG, Pombal, PB, Brazil. It was studied in a randomized block design with factorial scheme (2x4, two salinity levels (0.3 and 4.0 dSm-1 and four varieties of citrus rootstocks [1 -common Sunki mandarin (TSKC, 2 - Florida Rough lemon (LRF, 3 -Santa Cruz Rangpur lime (LCRSTC and 4-Volkamer lemon (LVK], with three replications. The citrus rootstocks varieties grown on hydroponic system and at 90 days after sowing the plants were evaluated by gas exchange and PSII fluorescence at 0, 24 and 48 hours after application of treatments to determine the times for the physiological establishment of salt stress. The first 48h under saline conditions promoted changes in gas exchange and PSII fluorescence in varieties TSKC, LRF and LCRSTC indicating the begin of physiological stress; the common ‘Sunki’ mandarin and the ‘Florida Rough’ lemon are the more sensitive genotypes to saline stress, in order hand the ‘Santa Cruz Rangpur’ lime and ‘Volkamer’ lemon are the genotypes more tolerant.

  10. Simultaneous time resolution of the emission spectra of fluorescent proteins and zooxanthellar chlorophyll in reef-building corals.

    Science.gov (United States)

    Gilmore, Adam M; Larkum, Anthony W D; Salih, Anya; Itoh, Shigeru; Shibata, Yutaka; Bena, Chiaki; Yamasaki, Hideo; Papina, Marina; Van Woesik, Robert

    2003-05-01

    Light is absorbed by photosynthetic algal symbionts (i.e. zooxanthellae) and by chromophoric fluorescent proteins (FP) in reef-building coral tissue. We used a streak-camera spectrograph equipped with a pulsed, blue laser diode (50 ps, 405 nm) to simultaneously resolve the fluorescence spectra and kinetics for both the FP and the zooxanthellae. Shallow water (corals showed rapidly decaying species and reciprocal rises in greener emission components indicating Förster resonance energy transfer (FRET) between FP populations. The energy transfer modes were around 250 ps, and the main decay modes of the acceptor FP were typically 1900-2800 ps. All zooxanthellae emitted similar spectra and kinetics with peak emission (approximately 683 nm) mainly from photosystem II (PSII) chlorophyll (chl) a. Compared with the FP, the PSII emission exhibited similar rise times but much faster decay times, typically around 640-760 ps. The fluorescence kinetics and excitation versus emission mapping indicated that the FP emission played only a minor role, if any, in chl excitation. We thus suggest the FP could only indirectly act to absorb, screen and scatter light to protect PSII and underlying and surrounding animal tissue from excess visible and UV light. We conclude that our time-resolved spectral analysis and simulation revealed new FP emission components that would not be easily resolved at steady state because of their relatively rapid decays due to efficient FRET. We believe the methods show promise for future studies of coral bleaching and for potentially identifying FP species for use as genetic markers and FRET partners, like the related green FP from Aequorea spp. PMID:12812294

  11. Effects of Nitrogen Application on Chlorophyll Fluorescence Parameters and Leaf Gas Exchange in Naked Oat

    Institute of Scientific and Technical Information of China (English)

    LIN Ye-chun; HU Yue-gao; REN Chang-zhong; GUO Lai-chun; WANG Chun-long; JIANG Ying; WANG Xue-jiao; Phendukani Hlatshwayo; ZENG Zhao-hai

    2013-01-01

    Naked oat (Avena nuda L.) was originated from China, where soil nitrogen (N) is low availability. The responses of chlorophyll (Chl.) lfuorescence parameters and leaf gas exchange to N application were analysed in this study. After the N application rate ranged from 60 to 120 kg ha-1, variable lfuorescence (Fv), the maximal lfuorescence (Fm), the maximal photochemical efifciency (Fv/Fm), quantum yield (ΦPS I) of the photosynthetic system II (PS II), electron transport rate (ETR), and photochemical quenching coefifcient (qP) increased with N application level, however, non-photochemical quenching coefifcient (qN) decreased. Moreover, there was no difference in initial lfuorescence (Fo) with further more N enhancement. The maximum net photosynthetic rate (Pmax), apparent dark respiration rate (Rd) and light saturation point (LSP) were improved with 40-56 kg N ha-1 as basal fertilizer and 24-40 kg N ha-1 as top dressing fertilizer applied at jointing stage. Initial quantum yield (α) was decreased with 24 kg N ha-1 as basal fertilizer and 56 kg N ha-1 as top dressing fertilizer.Flag-leaf net photosynthetic rate (Pn) was signiifcantly enhanced at the jointing and heading stages with 40-56 kg N ha-1 as basal fertilizer;in addition, increased at grain iflling stage of naked oat with 40-56 kg N ha-1 as top dressing fertilizer. 90 kg N ha-1 (50-70% as basal fertilizer and 30-50% as top dressing fertilizer) application is recommended to alleviate photodamage of photosystem and improve the photosynthetic rate in naked oat.

  12. The Validity Chlorophyll-a Estimation by Sun Induced Fluorescence in Estuarine Waters: An Analysis of Long-term (2003-2011) Water Quality Data from Tampa Bay, Florida (USA)

    Science.gov (United States)

    Moreno-Madrinan, Max Jacobo; Fischer, Andrew

    2012-01-01

    Satellite observation of phytoplankton concentration or chlorophyll-a is an important characteristic, critically integral to monitoring coastal water quality. However, the optical properties of estuarine and coastal waters are highly variable and complex and pose a great challenge for accurate analysis. Constituents such as suspended solids and dissolved organic matter and the overlapping and uncorrelated absorptions in the blue region of the spectrum renders the blue-green ratio algorithms for estimating chlorophyll-a inaccurate. Measurement of sun-induced chlorophyll fluorescence, on the other hand, which utilizes the near infrared portion of the electromagnetic spectrum, may provide a better estimate of phytoplankton concentrations. While modelling and laboratory studies have illustrated both the utility and limitations of satellite baseline algorithms based on the sun induced chlorophyll fluorescence signal, few have examined the empirical validity of these algorithms using a comprehensive long term in situ data set. In an unprecedented analysis of a long term (2003-2011) in situ monitoring data from Tampa Bay, Florida (USA), we assess the validity of the FLH product from the Moderate Resolution Imaging Spectrometer (MODIS) against chlorophyll ]a and a suite of water quality parameters taken in a variety of conditions throughout a large optically complex estuarine system. A systematic analysis of sampling sites throughout the bay is undertaken to understand how the relationship between FLH and in situ chlorophyll-a responds to varying conditions within the estuary including water depth, distance from shore and structures and eight water quality parameters. From the 39 station for which data was derived, 22 stations showed significant correlations when the FLH product was matched with in situ chlorophyll-alpha data. The correlations (r2) for individual stations within Tampa Bay ranged between 0.67 (n=28, pless than 0.01) and-0.457 (n=12, p=.016), indicating that

  13. A pair of light signaling factors FHY3 and FAR1 regulates plant immunity by modulating chlorophyll biosynthesis.

    Science.gov (United States)

    Wang, Wanqing; Tang, Weijiang; Ma, Tingting; Niu, De; Jin, Jing Bo; Wang, Haiyang; Lin, Rongcheng

    2016-01-01

    Light and chloroplast function is known to affect the plant immune response; however, the underlying mechanism remains elusive. We previously demonstrated that two light signaling factors, FAR-RED ELONGATED HYPOCOTYL 3 (FHY3) and FAR-RED IMPAIRED RESPONSE 1 (FAR1), regulate chlorophyll biosynthesis and seedling growth via controlling HEMB1 expression in Arabidopsis thaliana. In this study, we reveal that FHY3 and FAR1 are involved in modulating plant immunity. We showed that the fhy3 far1 double null mutant displayed high levels of reactive oxygen species and salicylic acid (SA) and increased resistance to Pseudomonas syringae pathogen infection. Microarray analysis revealed that a large proportion of pathogen-related genes, particularly genes encoding nucleotide-binding and leucine-rich repeat domain resistant proteins, are highly induced in fhy3 far1. Genetic studies indicated that the defects of fhy3 far1 can be largely rescued by reducing SA signaling or blocking SA accumulation, and by overexpression of HEMB1, which encodes a 5-aminolevulinic acid dehydratase in the chlorophyll biosynthetic pathway. Furthermore, we found that transgenic plants with reduced expression of HEMB1 exhibit a phenotype similar to fhy3 far1. Taken together, this study demonstrates an important role of FHY3 and FAR1 in regulating plant immunity, through integrating chlorophyll biosynthesis and the SA signaling pathway.

  14. Defects in leaf carbohydrate metabolism compromise acclimation to high light and lead to a high chlorophyll fluorescence phenotype in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Schmitz Jessica

    2012-01-01

    Full Text Available Abstract Background We have studied the impact of carbohydrate-starvation on the acclimation response to high light using Arabidopsis thaliana double mutants strongly impaired in the day- and night path of photoassimilate export from the chloroplast. A complete knock-out mutant of the triose phosphate/phosphate translocator (TPT; tpt-2 mutant was crossed to mutants defective in (i starch biosynthesis (adg1-1, pgm1 and pgi1-1; knock-outs of ADP-glucose pyrophosphorylase, plastidial phosphoglucomutase and phosphoglucose isomerase or (ii starch mobilization (sex1-3, knock-out of glucan water dikinase as well as in (iii maltose export from the chloroplast (mex1-2. Results All double mutants were viable and indistinguishable from the wild type when grown under low light conditions, but - except for sex1-3/tpt-2 - developed a high chlorophyll fluorescence (HCF phenotype and growth retardation when grown in high light. Immunoblots of thylakoid proteins, Blue-Native gel electrophoresis and chlorophyll fluorescence emission analyses at 77 Kelvin with the adg1-1/tpt-2 double mutant revealed that HCF was linked to a specific decrease in plastome-encoded core proteins of both photosystems (with the exception of the PSII component cytochrome b559, whereas nuclear-encoded antennae (LHCs accumulated normally, but were predominantly not attached to their photosystems. Uncoupled antennae are the major cause for HCF of dark-adapted plants. Feeding of sucrose or glucose to high light-grown adg1-1/tpt-2 plants rescued the HCF- and growth phenotypes. Elevated sugar levels induce the expression of the glucose-6-phosphate/phosphate translocator2 (GPT2, which in principle could compensate for the deficiency in the TPT. A triple mutant with an additional defect in GPT2 (adg1-1/tpt-2/gpt2-1 exhibited an identical rescue of the HCF- and growth phenotype in response to sugar feeding as the adg1-1/tpt-2 double mutant, indicating that this rescue is independent from the

  15. Effects of ambient versus reduced UV-B radiation on high arctic ¤Salix arctica¤ assessed by measurements and calculations of chlorophyll a fluorescence parameters from fluorescence transients

    DEFF Research Database (Denmark)

    Albert, K.R.; Mikkelsen, Teis Nørgaard; Ro-Poulsen, H.

    2005-01-01

    received approximately 90 and 40% of the ambient UV-B irradiance, respectively. The effects were examined through recordings of chlorophyll a fluorescence transients, determination of biomass and analysis of total carbon and nitrogen content and amount of soluble flavonoids in the leaves. The processing...... of light was analysed by means of the chlorophyll a fluorescence transient, using the so-called JIP test, as evolved by Reto J. Strasser and his coworkers. Reduction of the UV-B irradiance caused a rise in many of the fluorescence parameters during July, but not in August (late season). Thus increases...... on fluorescence parameters that were directly measured (e.g. F0 and FM) and those that were derived (e.g. quantum efficiencies, parameters per PSII reaction centres and per cross-section of leaf sample) are discussed in relation to one another, in relation to daily and seasonal variation, and from the perspective...

  16. Elevated CO2 interacts with herbivory to alter chlorophyll fluorescence and leaf temperature in Betula papyrifera and Populus tremuloides.

    Science.gov (United States)

    Nabity, Paul D; Hillstrom, Michael L; Lindroth, Richard L; DeLucia, Evan H

    2012-08-01

    Herbivory can influence ecosystem productivity, but recent evidence suggests that damage by herbivores modulates potential productivity specific to damage type. Because productivity is linked to photosynthesis at the leaf level, which in turn is influenced by atmospheric CO(2) concentrations, we investigated how different herbivore damage types alter component processes of photosynthesis under ambient and elevated atmospheric CO(2). We examined spatial patterns in chlorophyll fluorescence and the temperature of leaves damaged by leaf-chewing, gall-forming, and leaf-folding insects in aspen trees as well as by leaf-chewing insects in birch trees under ambient and elevated CO(2) at the aspen free-air CO(2) enrichment (FACE) site in Wisconsin. Both defoliation and gall damage suppressed the operating efficiency of photosystem II (ΦPSII) in remaining leaf tissue, and the distance that damage propagated into visibly undamaged tissue was marginally attenuated under elevated CO(2). Elevated CO(2) increased leaf temperatures, which reduced the cooling effect of gall formation and freshly chewed leaf tissue. These results provide mechanistic insight into how different damage types influence the remaining, visibly undamaged leaf tissue, and suggest that elevated CO(2) may reduce the effects of herbivory on the primary photochemistry controlling photosynthesis.

  17. Effect of Nitrogen Fertilization on Leaf Chlorophyll Fluorescence in Field-Grown Winter Wheat Under Rainfed Conditions

    Institute of Scientific and Technical Information of China (English)

    SHANGGUAN Zhou-ping; ZHENG Shu-xia; ZHANG Lei-ming; XUE Qing-wu

    2005-01-01

    The effect of nitrogen fertilization on leaf chlorophyll fluorescence was studied in field-grown winter wheat during grain filling under rainfed conditions in Loess Plateau. Results showed that the actual photochemical efficiency of PS Ⅱ reaction center (Ф PS Ⅱ) decreased significantly as leaf water stress progressed, however, the Ф PS was increased by nitrogen fertilization. The Ф PS Ⅱ of 0, 90 and 180 kg ha-1 nitrogen treatments at noon were 0.197, 0.279 and 0.283, respectively, which decreased by 57.7, 56.4 and 40.2% as compared was even higher than that in the moming. Application of nitrogen fertilizer significantly increased maximum photochemical efficiency (Fv/Fm), photochemical quenching coefficient (qP) and non-photochemical quenching coefficient (qNP). These results indicated that application of nitrogen fertilizer could increase the light energy conversion efficiency, the potential activity of photosynthetic reaction center, and the non-photochemical dissipation of excess light energy, which can prevent leaf photosynthetic apparatus from damage of treatments, indicating that the excess nitrogen was unfavorable to photosynthesis.

  18. Taxonomic and ecological relevance of the chlorophyll a fluorescence signature of tree species in mixed European forests.

    Science.gov (United States)

    Pollastrini, Martina; Holland, Vera; Brüggemann, Wolfgang; Bruelheide, Helge; Dănilă, Iulian; Jaroszewicz, Bogdan; Valladares, Fernando; Bussotti, Filippo

    2016-10-01

    The variability of chlorophyll a fluorescence (ChlF) parameters of forest tree species was investigated in 209 stands belonging to six European forests, from Mediterranean to boreal regions. The modifying role of environmental factors, forest structure and tree diversity (species richness and composition) on ChlF signature was analysed. At the European level, conifers showed higher potential performance than broadleaf species. Forests in central Europe performed better than those in Mediterranean and boreal regions. At the site level, homogeneous clusters of tree species were identified by means of a principal component analysis (PCA) of ChlF parameters. The discrimination of the clusters of species was influenced by their taxonomic position and ecological characteristics. The species richness influenced the tree ChlF properties in different ways depending on tree species and site. Tree species and site also affected the relationships between ChlF parameters and other plant functional traits (specific leaf area, leaf nitrogen content, light-saturated photosynthesis, wood density, leaf carbon isotope composition). The assessment of the photosynthetic properties of tree species, by means of ChlF parameters, in relation to their functional traits, is a relevant issue for studies in forest ecology. The connections of data from field surveys with remotely assessed parameters must be carefully explored. PMID:27265248

  19. Potential of the TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor for the monitoring of terrestrial chlorophyll fluorescence

    Science.gov (United States)

    Guanter, L.; Aben, I.; Tol, P.; Krijger, J. M.; Hollstein, A.; Köhler, P.; Damm, A.; Joiner, J.; Frankenberg, C.; Landgraf, J.

    2015-03-01

    Global monitoring of sun-induced chlorophyll fluorescence (SIF) is improving our knowledge about the photosynthetic functioning of terrestrial ecosystems. The feasibility of SIF retrievals from spaceborne atmospheric spectrometers has been demonstrated by a number of studies in the last years. In this work, we investigate the potential of the upcoming TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor satellite mission for SIF retrieval. TROPOMI will sample the 675-775 nm spectral window with a spectral resolution of 0.5 nm and a pixel size of 7 km × 7 km. We use an extensive set of simulated TROPOMI data in order to assess the uncertainty of single SIF retrievals and subsequent spatio-temporal composites. Our results illustrate the enormous improvement in SIF monitoring achievable with TROPOMI with respect to comparable spectrometers currently in-flight, such as the Global Ozone Monitoring Experiment-2 (GOME-2) instrument. We find that TROPOMI can reduce global uncertainties in SIF mapping by more than a factor of 2 with respect to GOME-2, which comes together with an approximately 5-fold improvement in spatial sampling. Finally, we discuss the potential of TROPOMI to map other important vegetation parameters at a global scale with moderate spatial resolution and short revisit time. Those include leaf photosynthetic pigments and proxies for canopy structure, which will complement SIF retrievals for a self-contained description of vegetation condition and functioning.

  20. Physiological responses of Brassica napus to fulvic acid under water stress:Chlorophyll a fluorescence and antioxidant enzyme activity

    Institute of Scientific and Technical Information of China (English)

    Ramin Lotfi; Mohammad Pessarakli; Puriya Gharavi-Kouchebagh; Hossein Khoshvaghti

    2015-01-01

    The ameliorative effect of fulvic acid (0, 300, and 600 mg L−1) on photosystem II and antioxidant enzyme activity of the rapeseed (Brassica napus L.) plant under water stress (60, 100, and 140 mm evaporation from class A pan) was studied using split plots in a randomized complete block design with three replications. Results indicated that application of fulvic acid (FA) improved the maximum quantum efficiency of PSII (Fv/Fm) and performance index (PI) of plants under both well-watered and limited-water conditions. The time span from Fo to Fm and the energy necessary for the closure of all reaction centers was significantly increased, but the size of the plastoquinone pool was reduced with increasing water stress levels. Plants treated with FA had higher peroxidase and catalase activities under all irrigation conditions. Activities of ascorbate peroxidase and superoxide dismutase in plants increased with increasing water stress. Malondialdehyde increased under severe water stress, but application of FA significantly decreased lipid peroxidation. Production of reactive oxygen species (ROS) is a common phenomenon in plants under stress. Under this condition, the balance between the production of ROS and the quenching activity of antioxidants is upset, often resulting in oxidative damage. In this study, application of FA significantly increased fluorescence of chlorophyll a, inhibiting ROS production and enhancing antioxidant enzymes activity that destroyed ROS. Thus, ROS in plant cells was reduced under water stress by application of FA and consequently lipid peroxidation was reduced.

  1. Physiological responses of Brassica napus to fulvic acid under water stress: Chlorophyll a fluorescence and antioxidant enzyme activity

    Institute of Scientific and Technical Information of China (English)

    Ramin; Lotfi; Mohammad; Pessarakli; Puriya; Gharavi-Kouchebagh; Hossein; Khoshvaghti

    2015-01-01

    The ameliorative effect of fulvic acid(0, 300, and 600 mg L-1) on photosystem II and antioxidant enzyme activity of the rapeseed(Brassica napus L.) plant under water stress(60, 100, and 140 mm evaporation from class A pan) was studied using split plots in a randomized complete block design with three replications. Results indicated that application of fulvic acid(FA) improved the maximum quantum efficiency of PSII(Fv/Fm)and performance index(PI) of plants under both well-watered and limited-water conditions. The time span from Foto Fmand the energy necessary for the closure of all reaction centers was significantly increased, but the size of the plastoquinone pool was reduced with increasing water stress levels. Plants treated with FA had higher peroxidase and catalase activities under all irrigation conditions. Activities of ascorbate peroxidase and superoxide dismutase in plants increased with increasing water stress. Malondialdehyde increased under severe water stress, but application of FA significantly decreased lipid peroxidation. Production of reactive oxygen species(ROS) is a common phenomenon in plants under stress. Under this condition, the balance between the production of ROS and the quenching activity of antioxidants is upset, often resulting in oxidative damage. In this study, application of FA significantly increased fluorescence of chlorophyll a, inhibiting ROS production and enhancing antioxidant enzymes activity that destroyed ROS. Thus, ROS in plant cells was reduced under water stress by application of FA and consequently lipid peroxidation was reduced.

  2. Herbicidal effects of harmaline from Peganum harmala on photosynthesis of Chlorella pyrenoidosa: probed by chlorophyll fluorescence and thermoluminescence.

    Science.gov (United States)

    Deng, Chunnuan; Shao, Hua; Pan, Xiangliang; Wang, Shuzhi; Zhang, Daoyong

    2014-10-01

    The herbicidal effects of harmaline extracted from Peganum harmala seed on cell growth and photosynthesis of green algae Chlorella pyrenoidosa were investigated using chlorophyll a fluorescence and thermoluminescence techniques. Exposure to harmaline inhibited cell growth, pigments contents and oxygen evolution of C. pyrenoidosa. Oxygen evolution was more sensitive to harmaline toxicity than cell growth or the whole photosystem II (PSII) activity, maybe it was the first target site of harmaline. The JIP-test parameters showed that harmaline inhibited the donor side of PSII. Harmaline decreased photochemical efficiency and electron transport flow of PSII but increased the energy dissipation. The charge recombination was also affected by harmaline. Amplitude of the fast phase decreased and the slow phase increased at the highest level of harmaline. Electron transfer from QA(-) to QB was inhibited and backward electron transport flow from QA(-) to oxygen evolution complex was enhanced at 10 μg mL(-1) harmaline. Exposure to 10 μg mL(-1) harmaline caused appearance of C band in thermoluminescence. Exposure to 5 μg mL(-1) harmaline inhibited the formation of proton gradient. The highest concentration of harmaline treatment inhibited S3QB(-) charge recombination but promoted formation of QA(-)YD(+) charge pairs. P. harmala harmaline may be a promising herbicide because of its inhibition of cell growth, pigments synthesis, oxygen evolution and PSII activities.

  3. Early stage toxicity of excess copper to photosystem II of Chlorella pyrenoidosa-OJIP chlorophyll a fluorescence analysis

    Institute of Scientific and Technical Information of China (English)

    XIA Jianrong; TIAN Qiran

    2009-01-01

    Acute toxicity of excess Cu on the photosynthetic performance of Chlorella pyrenoidosa was examined by using chlorophyll a fluorescence transients and JIP-test after exposure to elevated Cu concentrations for a short period of time.High Cu concentration resulted in a significant suppression in photosynthesis and respiration.The absorption flux (ABS/RC) per PSⅡ reaction center increased with increasing Cu concentration,but the electron transport flux (ET_0/RC) decreased.Excess Cu had an insignificant effect on the trapping flux (TR_0/RC).The decline in the efficiency with which a trapped exciton can move an electron into the electron transport chain further than QA- (ψ_o),the maximal quantum yield of primary photochemistry (φP_o),and the quantum yield of electron transport (φE_o) were also observed.The amount of active PSⅡ reaction centers per excited cross section (RC/CS) was also in consistency with the change of photosynthesis when cells were exposed to excess Cu concentration.JIP-test parameters had a good linear relationship with photosynthetic O_2 evolution.These results suggested that the decrease of photosynthesis in exposure to excess Cu may be a result of the inactivation of PSⅡ reaction centers and inhibition of electron transport in the acceptor side.

  4. Evaluation of Chlorophyll Fluorescence and Biochemical Traits of Lettuce under Drought Stress and Super Absorbent or Bentonite Application

    Directory of Open Access Journals (Sweden)

    Akram Valizadeh Ghale Beig

    2014-03-01

    Full Text Available The effects of two superabsorbents (natural-bentonite and (synthetic-A 200 on the chlorophyll fluorescence index, proline accumulation, phenolic compounds, antioxidant activity and total carbohydrate in lettuce (Lactuca sativa L. was evaluated. For this purpose, a factorial experiment using completely randomized design with superabsorbents at 3 levels (0, 0.15, 0.30 w/w%, drought stress at 2 levels (60 and 100% of field capacity and 4 replicates was conducted. Results showed that photosystem photochemical efficiency (Fv/Fm II under drought stress (60% FC as well as lower levels of bentonite superabsorbent polymer reduced. The minimum and maximum proline content were obtained in 0.3% bentonite, 100% FC and 0 benetonite, 60% FC, respectively. The lowest and highest phenolic compounds was corresponded to the highest levels in both super absorbents and control respectively, so that the super absorbent and bentonite, reduced phenolic compounds by 62.65 and 66.21% compared to control. 0 and 0.15 wt % bentonite in high drought stress (60% FC showed the highest and 0.3 wt % bentonite and 100% FC attained the lowest level of antioxidant activity. Control bentonite treatment beds at 60% FC and beds containing 0.3 wt. % bentonite in 100% FC, showed the lowest and the highest total carbohydrate content respectively. Results of this study indicate that bentonite can reduce the negative effects of drought stress similar to artificial super absorbent.

  5. Physiological responses of Brassica napus to fulvic acid under water stress: Chlorophyll a fluorescence and antioxidant enzyme activity

    Directory of Open Access Journals (Sweden)

    Ramin Lotfi

    2015-10-01

    Full Text Available The ameliorative effect of fulvic acid (0, 300, and 600 mg L− 1 on photosystem II and antioxidant enzyme activity of the rapeseed (Brassica napus L. plant under water stress (60, 100, and 140 mm evaporation from class A pan was studied using split plots in a randomized complete block design with three replications. Results indicated that application of fulvic acid (FA improved the maximum quantum efficiency of PSII (Fv/Fm and performance index (PI of plants under both well-watered and limited-water conditions. The time span from Fo to Fm and the energy necessary for the closure of all reaction centers was significantly increased, but the size of the plastoquinone pool was reduced with increasing water stress levels. Plants treated with FA had higher peroxidase and catalase activities under all irrigation conditions. Activities of ascorbate peroxidase and superoxide dismutase in plants increased with increasing water stress. Malondialdehyde increased under severe water stress, but application of FA significantly decreased lipid peroxidation. Production of reactive oxygen species (ROS is a common phenomenon in plants under stress. Under this condition, the balance between the production of ROS and the quenching activity of antioxidants is upset, often resulting in oxidative damage. In this study, application of FA significantly increased fluorescence of chlorophyll a, inhibiting ROS production and enhancing antioxidant enzymes activity that destroyed ROS. Thus, ROS in plant cells was reduced under water stress by application of FA and consequently lipid peroxidation was reduced.

  6. SIGNALS REGARDING THE ISOLATION OF CHLOROPHYL-FREE ALGAE IN THE MILK OF SOME HEALTHY COWS AND SOME WITH MAMITTIS

    OpenAIRE

    OGNEAN, Laurent; Dana PUSTA; Oana, Liviu

    2002-01-01

    In the microbiological investigation, made on samples of normal; (n=412) and mastitic (n=482) milk, proceeded from eight dairy cows farm, in Transilvania, it was signal the presence of the algae without chlorophyl belonging to Prototheca, forming together with bacteria and fungi the micro flora of the mammary gland. The alga content of normal milk was signaled only in two farms (2.27%, respectively 1.21%), being established to 0.72%. In the case of mastitic milk the percentage of ...

  7. Ratiometric fluorescence signalling of fluoride ions by an amidophthalimide derivative

    Indian Academy of Sciences (India)

    Moloy Sarkar; Raghavendra Yellampalli; Bhaswati Bhattacharya; Ravi Kumar Kanaparthi; Anunay Samanta

    2007-03-01

    Fluorescence behaviour of 4-benzoylamido-N-methylphthalimide (1), designed and developed for selective detection of fluoride ions, is reported. 1 displays F--induced colour change that allows its detection with the naked eye. The F- specificity of the sensor system is evident from the fact that unlike F-, other halides do not affect the absorption characteristics of 1. Apart from the colorimetric response, the fluorescence output of 1 is also modulated by F- in a manner that permits ratiometric fluorescence signalling of F- as well. It is found that the system can detect F- in the concentration range of 10- 60 M. The results of the experiments and theoretical calculations unambiguously suggest that the changes of the electronic absorption and fluorescence behaviour of 1, which have been exploited for signalling purpose, are due to F--induced deprotonation of the 4-amido moiety of the sensor system.

  8. Effects of NaCl Stress on Chlorophyll Fluorescence Parameters in Cinnamomum japonicum var. chenii%NaCl胁迫对普陀樟叶绿素荧光参数的影响

    Institute of Scientific and Technical Information of China (English)

    李影丽; 汪奎宏; 杜国坚; 许利群; 杨华; 肖纪军

    2008-01-01

    [Objective] Study on the changes of chlorophyll fluorescence parameters in Cinnamomum japonicum var. chenii under NaCl stress. [Method] The seedling growth increment, chlorophyll content and chlorophyll fluorescence parameters in leaves of 1-year old Cinnamomum japonicum var. chenii were investigated in field experiment. [Result] Under NaCl stress, seedling growth increment reduced and the chlorophyll content decreased to a stable value; changes of Fv/Fm and Fv/Fo showed identical increasing trend and double peak type. With the aggravation of salt stress, most variations were ob- served in Fo, correlations among chlorophyll fluorescence parameters presented "rise-drop" trend (in the treatment of 7 g/L NaCl). [Condusion] Cinna-momum japonicum var. chenii is endowed with strong salt resistance and wide adaptability.

  9. Monitoring and Assessing the 2012 Drought in the Great Plains: Analyzing Satellite-Retrieved Solar-Induced Chlorophyll Fluorescence, Drought Indices, and Gross Primary Production

    OpenAIRE

    Siheng Wang; Changping Huang; Lifu Zhang; Yi Lin; Yi Cen; Taixia Wu

    2016-01-01

    We examined the relationship between satellite measurements of solar-induced chlorophyll fluorescence (SIF) and several meteorological drought indices, including the multi-time-scale standard precipitation index (SPI) and the Palmer drought severity index (PDSI), to evaluate the potential of using SIF to monitor and assess drought. We found significant positive relationships between SIF and drought indices during the growing season (from June to September). SIF was found to be more sensitive ...

  10. Cold-induced sudden reversible lowering of in vivo chlorophyll fluorescence after saturating light pulses : a sensitive marker for chilling susceptibility.

    Science.gov (United States)

    Larcher, W; Neuner, G

    1989-03-01

    In chilling-sensitive plants (Glycine max, Saintpaulia ionantha, Saccharum officinarum) a sudden reversible drop in chlorophyll fluorescence occurs during photosynthetic induction immediately following saturating light pulses at low temperatures in the range 4 to 8 degrees C. A comparison of two soybean cultivars of different chilling sensitivities revealed that this phenomenon, termed lowwave, indicates specific thresholds of low temperature stress. Its occurrence under controlled chilling can be regarded as a quantitative marker for screening chilling susceptibility in angiosperms. PMID:16666615

  11. Effects of different concentrations of nitrogen and phosphorus on chlorophyll biosynthesis,chlorophyll a fluorescence,and photosynthesis In Larix olgensis seedlings

    Institute of Scientific and Technical Information of China (English)

    Wu Chu; Wang Zhengquan; Sun Hailong; Guo Shenglei

    2006-01-01

    In our experiments,one-year-old Larix olgensis seedlings were cultivated in sand,and supplied with solutions with different concentrations of nitrate or phosphate.The effects of nitrogen and phosphorus supply on chlorophyll biosynthesis,total nitrogen content,and photosynthetic rate were studied.The experimental results are listed below: 1) 5-aminolevulinic acid (ALA) synthetic rate increased as nitrate concentrations supplied to larch seedlings increased from 1 to 8 mmol/L.But the rate decreased by 17% when nitrate concentration increased to 16 mmol/L,in contrast to the control.Under phosphate treatments,ALA synthetic rates were similar to those under nitrate treatments.The activities of porphobilinogen (PBG)synthase reached a maximum when larch seedlings were supplied with 8 mmol/L of nitrate or 1 mmol/L of phosphate.2) When larch seedlings were supplied with 8 mmol/L of nitrate and 0.5 mmol/L of phosphate,the contents of chlorophyll a,chlorophyll b,total chlorophyll,and carotenoids reached a maximum.The total nitrogen contents in leaves increased as nitrate concentrations increased.3) When phosphate concentrations increased from 0.125 to 1 mmol/L,the total nitrogen contents in leaves slightly increased;however,continuous increase of phosphate concentrations resulted in the decrease in total nitrogen contents in leaves.When nitrate concentrations increased from 1 to 8 mmol/L,soluble protein contents in leaves increased in general,and continuous increase of nitrate concentrations induced a decrease in soluble protein contents in leaves.Under treatment of 0.25 mmol/L of phosphate,the soluble protein contents reached a maximum.4) In general,Fv/Fm increased as nitrate concentrations increased from 1 to 8 mmol/L,and continuous increase of nitrate concentration resulted in decrease in FvlFm.The similar changes occurred under phosphate treatments.As nitrate concentrations increased from 1 to 8 mmol/L,photosynthetic rates gradually increased,but when nitrate

  12. Upward and downward solar-induced chlorophyll fluorescence yield indices of four tree species as indicators of traffic pollution in Valencia

    International Nuclear Information System (INIS)

    Passive steady-state chlorophyll fluorescence (Fs) provides a direct diagnosis of the functional status of vegetation photosynthesis. With the prospect of mapping Fs using remote sensing techniques, field measurements are mandatory to understand to which extent Fs allows detecting plant stress in different environments. Trees of four common species in Valencia were classified in either a low or a high local traffic exposure class based on their leaf magnetic value. Upward and downward hyperspectral fluorescence yield (FY) and indices based on the two Fs peaks (at 687 and 741 nm) were calculated. FY indices of P. canariensis and P. x acerifolia were significantly different between the two traffic exposure classes defined, but not for C. australis nor M. alba. While chlorophyll content could not indicate the difference between low and high traffic exposure, the FY(687)/FY(741) peak ratio increased significantly (p < 0.05) for both leaf sides for the higher traffic exposure class. - Highlights: ► Potential of fluorescence yield parameters as stress detectors for traffic pollution. ► SIRM functions as a measure for local traffic emissions at tree level. ► Some urban trees show a fluorescence yield response to increased traffic exposure. ► Fs is a more sensitive indicator of (traffic) pollution stress than Chl content as such. - Fluorescence yield parameters as stress detectors for traffic-exposed urban trees are tested.

  13. FluorMODgui V3.0: A graphic user interface for the spectral simulation of leaf and canopy chlorophyll fluorescence

    Science.gov (United States)

    Zarco-Tejada, P. J.; Miller, J. R.; Pedrós, R.; Verhoef, W.; Berger, M.

    2006-06-01

    The FluorMODgui Graphic User Interface (GUI) software package developed within the frame of the FluorMOD project Development of a Vegetation Fluorescence Canopy Model is presented in this manuscript. The FluorMOD project was launched in 2002 by the European Space Agency (ESA) to advance the science of vegetation fluorescence simulation through the development and integration of leaf and canopy fluorescence models based on physical methods. The design of airborne or space missions dedicated to the measurement of solar-induced chlorophyll fluorescence using remote-sensing instruments require physical methods for quantitative feasibility analysis and sensor specification studies. The FluorMODgui model developed as part of this project is designed to simulate the effects of chlorophyll fluorescence at leaf and canopy levels using atmospheric inputs, running the leaf model, FluorMODleaf, and the canopy model, FluorSAIL, independently, through a coupling scheme, and by a multiple iteration protocol to simulate changes in the viewing geometry and atmospheric characteristics. Inputs for the FluorMODleaf model are the number of leaf layers, chlorophyll a+ b content, water equivalent thickness, dry matter content, fluorescence quantum efficiency, temperature, species type, and stoichiometry. Inputs for the FluorSAIL canopy model are a MODTRAN-4 6-parameter spectra or measured direct horizontal irradiance and diffuse irradiance spectra, a soil reflectance spectrum, leaf reflectance & transmittance spectra and a excitation-fluorescence response matrix in upward and downward directions (all from FluorMODleaf), 2 PAR-dependent coefficients for the fluorescence response to light level, relative azimuth angle and viewing zenith angle, canopy leaf area index, leaf inclination distribution function, and a hot spot parameter. Outputs available in the 400-1000 nm spectral range from the graphical user interface, FluorMODgui, are the leaf spectral reflectance and transmittance, and the

  14. Light screening in lichen cortices can be quantified by chlorophyll fluorescence techniques for both reflecting and absorbing pigments.

    Science.gov (United States)

    Solhaug, Knut Asbjørn; Larsson, Per; Gauslaa, Yngvar

    2010-04-01

    Lichens, representing mutualistic symbioses between photobionts and mycobionts, often accumulate high concentrations of secondary compounds synthesized by the fungal partner. Light screening is one function for cortical compounds being deposited as crystals outside fungal hyphae. These compounds can non-destructively be extracted by 100% acetone from air-dry living thalli. Extraction of atranorin from Physcia aipolia changed the lichen colour from pale grey to green in the hydrated state, whereas acetone-rinsed and control thalli were all pale grey when dry. Removal of parietin from Xanthoria parietina changed the colour of desiccated thalli from orange to grey. Colour changes were quantified by reflectance measurements. By a new chlorophyll fluorescence method, screening was assessed as the decrease in incident irradiance (PAR) necessary to reach identical effective quantum yields of PSII (Phi(PSII)) in acetone-rinsed and control thalli. Thereby, we estimated a screening efficiency due to cortical atranorin crystals at 61, 38, and 40% of blue, green and red light, respectively, whereas parietin screened 81, 27 and 1% of these wavelength ranges. Removal of atranorin caused similar levels of increased photoinhibition for P. aipolia in blue, green and red light, whereas parietin-deficient thalli of X. parietina exhibited increased photoinhibition with decreasing wavelengths. Atranorin possibly prevents water from entering the spaces between the hyphae in the cortex. The air-filled cavities with white atranorin crystals reflect excess light, whereas the yellow compound parietin absorbs excess light. Thereby, both atranorin and parietin play significant photoprotective roles for symbiotic green algae, but with compound-specific screening mechanisms.

  15. Dynamics of leaf gas exchange, chlorophyll fluorescence and stem diameter changes during freezing and thawing of Scots pine seedlings.

    Science.gov (United States)

    Lindfors, Lauri; Hölttä, Teemu; Lintunen, Anna; Porcar-Castell, Albert; Nikinmaa, Eero; Juurola, Eija

    2015-12-01

    Boreal trees experience repeated freeze-thaw cycles annually. While freezing has been extensively studied in trees, the dynamic responses occurring during the freezing and thawing remain poorly understood. At freezing and thawing, rapid changes take place in the water relations of living cells in needles and in stem. While freezing is mostly limited to extracellular spaces, living cells dehydrate, shrink and their osmotic concentration increases. We studied how the freezing-thawing dynamics reflected on leaf gas exchange, chlorophyll fluorescence and xylem and living bark diameter changes of Scots pine (Pinus sylvestris L.) saplings in controlled experiments. Photosynthetic rate quickly declined following ice nucleation and extracellular freezing in xylem and needles, almost parallel to a rapid shrinking of xylem diameter, while that of living bark followed with a slightly longer delay. While xylem and living bark diameters responded well to decreasing temperature and water potential of ice, the relationship was less consistent in the case of increasing temperature. Xylem showed strong temporal swelling at thawing suggesting water movement from bark. After thawing xylem diameter recovered to a pre-freezing level but living bark remained shrunk. We found that freezing affected photosynthesis at multiple levels. The distinct dynamics of photosynthetic rate and stomatal conductance reveals that the decreased photosynthetic rate reflects impaired dark reactions rather than stomatal closure. Freezing also inhibited the capacity of the light reactions to dissipate excess energy as heat, via non-photochemical quenching, whereas photochemical quenching of excitation energy decreased gradually with temperature in agreement with the gas exchange data. PMID:26423334

  16. Characteristics of Gas Exchange, Chlorophyll Fluorescence and Expression of Key Enzymes in Photosynthesis During Leaf Senescence in Rice Plants

    Institute of Scientific and Technical Information of China (English)

    Xiao-Yan WENG; Hong-Xia XU; De-An JIANG

    2005-01-01

    Gas exchange, chlorophyll (Chl) fluorescence, photosynthetic pigments, and the expression of Rubisco and Rubisco activase in flag leaves of rice (Oryza sativa L.) from the heading to mature grain stage were investigated. The results showed that the photosynthetic capacity declined after full expansion of flag leaves. The decline of photosynthetic rate (Pn) in two cultivars during natural senescence was accompanied by a decrease in Chl content, as well as in the Rubisco and Rubisco activase contents. The Rubisco and Rubisco activase contents in Zhenong 966 decreased faster than that in Zhenong 952. The Pn diminished without a decrease in intercellular CO2 concentration during the early senescence of flag leaves, indicating that lower photosynthetic capacity is not caused by stomatal limitation but by reduced carboxylation efficiency. During the senescence of flag leaves, the correlation between the change in photosynthetic capacity and the variation in the abundance of Rubisco and Rubisco activase suggested that the decline in Pn of flag leaves could be attributed to the lower level of rbcS and rca transcripts. The (φ)PSⅡ and the electron transport rate appeared in the same rate as Pn. However, excitation pressure (1-qP) showed a different pattern and there was an inverse linear correlation between increased excitation pressure and the reduced Rubisco. Therefore, it is likely that the increased excitation pressure resulted from saturation of the electron transport chain, owing to a limitation of the reductant used by the Calvin cycle; in addition, the change in excitation pressure could further mediate the expression of the rbcS and rca genes, resulting in a fast reduction in Rubisco content.

  17. Light screening in lichen cortices can be quantified by chlorophyll fluorescence techniques for both reflecting and absorbing pigments.

    Science.gov (United States)

    Solhaug, Knut Asbjørn; Larsson, Per; Gauslaa, Yngvar

    2010-04-01

    Lichens, representing mutualistic symbioses between photobionts and mycobionts, often accumulate high concentrations of secondary compounds synthesized by the fungal partner. Light screening is one function for cortical compounds being deposited as crystals outside fungal hyphae. These compounds can non-destructively be extracted by 100% acetone from air-dry living thalli. Extraction of atranorin from Physcia aipolia changed the lichen colour from pale grey to green in the hydrated state, whereas acetone-rinsed and control thalli were all pale grey when dry. Removal of parietin from Xanthoria parietina changed the colour of desiccated thalli from orange to grey. Colour changes were quantified by reflectance measurements. By a new chlorophyll fluorescence method, screening was assessed as the decrease in incident irradiance (PAR) necessary to reach identical effective quantum yields of PSII (Phi(PSII)) in acetone-rinsed and control thalli. Thereby, we estimated a screening efficiency due to cortical atranorin crystals at 61, 38, and 40% of blue, green and red light, respectively, whereas parietin screened 81, 27 and 1% of these wavelength ranges. Removal of atranorin caused similar levels of increased photoinhibition for P. aipolia in blue, green and red light, whereas parietin-deficient thalli of X. parietina exhibited increased photoinhibition with decreasing wavelengths. Atranorin possibly prevents water from entering the spaces between the hyphae in the cortex. The air-filled cavities with white atranorin crystals reflect excess light, whereas the yellow compound parietin absorbs excess light. Thereby, both atranorin and parietin play significant photoprotective roles for symbiotic green algae, but with compound-specific screening mechanisms. PMID:20135325

  18. Chlorophyll fluorescence induction kinetics and yield responses in rainfed crops with variable potassium nutrition in K deficient semi-arid alfisols.

    Science.gov (United States)

    Srinivasarao, Ch; Shanker, Arun K; Kundu, Sumanta; Reddy, Sharanbhoopal

    2016-07-01

    Optimum potassium (K) nutrition in semi-arid regions may help crop plants to overcome constraints in their growth and development such as moisture stress, leading to higher productivity of rainfed crops, thus judicious K management is essential. A study was conducted to evaluate the importance of K nutrition on physiological processes like photosynthesis through chlorophyll a fluorescence and chlorophyll fluorescence induction kinetics (OJIP) of rainfed crops viz., maize (Zea mays L.), pearl millet (Pennisetum glaucum), groundnut (Arachis hypogaea), sunflower (Helianthus annuus), castor (Ricinus communis L.) and cotton (Gossypium hirsutum) under water stress conditions by studying their growth attributes, water relations, yield, K uptake and use efficiency under varied K levels. Highest chlorophyll content was observed under K60 in maize and pearl millet. Narrow and wide Chl a:b ratio was observed in castor and groundnut respectively. The fluorescence yield decreased in the crops as K dosage increased, evidenced by increasing of all points (O, J, I and P) of the OJIP curves. The fluorescence transient curve for K60 was lower than K0 and K40 for all the crops. Potassium levels altered the fluorescence induction and impaired photosynthetic systems in all the crops studied. There was no distinct trend observed in leaf water potential of crops under study. Uptake of K was high in sunflower with increased rate of K application. Quantitatively, K uptake by castor crop was lesser compared to all other crops. Our results indicate that the yield reduction under low K was due to the low capacity of the crops to translocate K from non-photosynthetic organs such as stems and petioles to upper leaves and harvested organs and this in turn influenced the capacity of the crops to produce a high economic yield per unit of K taken up thus reducing utilization efficiency of K. PMID:27101276

  19. Sun-induced chlorophyll fluorescence reveals strong representation of photosynthesis at ecosystem level in rice paddy field in Japan

    Science.gov (United States)

    Kato, T.; Tsujimoto, K.; Nasahara, K. N.; Akitsu, T.; Ono, K.; Miyata, A.

    2015-12-01

    Chlorophyll fluorescence emission from ecosystem induced by sunlight (Sun-Induced Fluorescence: SIF) is now a key factor to accurately estimate the ecosystem-level photosynthesis activity as suggested by satellite studies, and has been recently detected by satellites [Frankenberg et al., 2011; Guanter et al., 2012; Joiner et al., 2013] and measured at field stations [Daumard et al., 2010; Porcar-Castell, 2011]. However, the few example of field-based assessment on the representation ability reduces its value for the availability to better understand the dynamics in CO2uptake by land ecosystem. To elucidate the potential of SIF to estimate ecosystem GPP in typical Asian crop type, the canopy-top SIF was calculated from the spectrum data in Japanese rice paddy field in Mase in central Japan (36°03'N, 140°01'E, 11 m a.s.l.), and compared with eddy-tower measured GPP on half-hourly and daily bases during seven years from 2006 to 2012. The rice (Oriza sativa L.; cultivar Koshihikari) was transplanted in May and harvested in September normally. The SIF was estimated from the spectrums of downward Sun irradiance and upward canopy-reflected radiance measured at the height of 3m above ground by HemiSpherical Spectro-Radiometer (HSSR), consisting of the spectroradiometer (MS-700, Eko inc., Tokyo, Japan) with the full-width at half maximum (FWHM) of 10 nm and wavelength interval of 3.3 nm. The SIF around 760nm (O2-A band: Fs760) was calculated according to the Fraunhofer Line Depth principle [Maier et al., 2003] with several additional arrangements. The GPP increased almost linearly as both Fs760 and APAR (Absorbed Photosyntethically Active Radiation) increased based on monthly-averaged diurnal courses during the growing season in 2006. The slopes of their regression lines differed much among the months in APAR, but in Fs760. These nearly constant relationships among the months between GPP and Fs760 were kept for all the observation years. Daily averaged GPP and Fs760

  20. Mg chelatase in chlorophyll synthesis and retrograde signaling in Chlamydomonas reinhardtii: CHLI2 cannot substitute for CHLI1.

    Science.gov (United States)

    Brzezowski, Pawel; Sharifi, Marina N; Dent, Rachel M; Morhard, Marius K; Niyogi, Krishna K; Grimm, Bernhard

    2016-06-01

    The oligomeric Mg chelatase (MgCh), consisting of the subunits CHLH, CHLI, and CHLD, is located at the central site of chlorophyll synthesis, but is also thought to have an additional function in regulatory feedback control of the tetrapyrrole biosynthesis pathway and in chloroplast retrograde signaling. In Arabidopsis thaliana and Chlamydomonas reinhardtii, two genes have been proposed to encode the CHLI subunit of MgCh. While the role of CHLI1 in A. thaliana MgCh has been substantially elucidated, different reports provide inconsistent results with regard to the function of CHLI2 in Mg chelation and retrograde signaling. In the present report, the possible functions of both isoforms were analyzed in C. reinhardtii Knockout of the CHLI1 gene resulted in complete loss of MgCh activity, absence of chlorophyll, acute light sensitivity, and, as a consequence, down-regulation of tetrapyrrole biosynthesis and photosynthesis-associated nuclear genes. These observations indicate a phenotypical resemblance of chli1 to the chlh and chld C. reinhardtii mutants previously reported. The key role of CHLI1 for MgCh reaction in comparison with the second isoform was confirmed by the rescue of chli1 with genomic CHLI1 Because CHLI2 in C. reinhardtii shows lower expression than CHLI1, strains overexpressing CHLI2 were produced in the chli1 background. However, no complementation of the chli1 phenotype was observed. Silencing of CHLI2 in the wild-type background did not result in any changes in the accumulation of tetrapyrrole intermediates or of chlorophyll. The results suggest that, unlike in A. thaliana, changes in CHLI2 content observed in the present studies do not affect formation and activity of MgCh in C. reinhardtii. PMID:26809558

  1. Red fluorescence in reef fish: A novel signalling mechanism?

    Directory of Open Access Journals (Sweden)

    Siebeck Ulrike E

    2008-09-01

    Full Text Available Abstract Background At depths below 10 m, reefs are dominated by blue-green light because seawater selectively absorbs the longer, 'red' wavelengths beyond 600 nm from the downwelling sunlight. Consequently, the visual pigments of many reef fish are matched to shorter wavelengths, which are transmitted better by water. Combining the typically poor long-wavelength sensitivity of fish eyes with the presumed lack of ambient red light, red light is currently considered irrelevant for reef fish. However, previous studies ignore the fact that several marine organisms, including deep sea fish, produce their own red luminescence and are capable of seeing it. Results We here report that at least 32 reef fishes from 16 genera and 5 families show pronounced red fluorescence under natural, daytime conditions at depths where downwelling red light is virtually absent. Fluorescence was confirmed by extensive spectrometry in the laboratory. In most cases peak emission was around 600 nm and fluorescence was associated with guanine crystals, which thus far were known for their light reflecting properties only. Our data indicate that red fluorescence may function in a context of intraspecific communication. Fluorescence patterns were typically associated with the eyes or the head, varying substantially even between species of the same genus. Moreover red fluorescence was particularly strong in fins that are involved in intraspecific signalling. Finally, microspectrometry in one fluorescent goby, Eviota pellucida, showed a long-wave sensitivity that overlapped with its own red fluorescence, indicating that this species is capable of seeing its own fluorescence. Conclusion We show that red fluorescence is widespread among marine fishes. Many features indicate that it is used as a private communication mechanism in small, benthic, pair- or group-living fishes. Many of these species show quite cryptic colouration in other parts of the visible spectrum. High inter

  2. Chlorophyll fluorescence of tropical tree species in a semi-deciduous forest gap Fluorescência da clorofila de espécies arbóreas tropicais em uma clareira de floresta semidecídua

    OpenAIRE

    Rafael Vasconcelos Ribeiro; Gustavo Maia Souza; Angelo Gilberto Manzatto; Eduardo Caruso Machado; Ricardo Ferraz de Oliveira

    2004-01-01

    The characterization of different ecological groups in a forest formation/succession is unclear. To better define the different successional classes, we have to consider ecophysiological aspects, such as the capacity to use or dissipate the light energy available. The main objective of this work was to assess the chlorophyll fluorescence emission of tropical tree species growing in a gap of a semi-deciduous forest. Three species of different ecological groups were selected: Croton floribundus...

  3. SIGNALS REGARDING THE ISOLATION OF CHLOROPHYL-FREE ALGAE IN THE MILK OF SOME HEALTHY COWS AND SOME WITH MAMITTIS

    Directory of Open Access Journals (Sweden)

    Laurent OGNEAN

    2002-03-01

    Full Text Available In the microbiological investigation, made on samples of normal; (n=412 and mastitic (n=482 milk, proceeded from eight dairy cows farm, in Transilvania, it was signal the presence of the algae without chlorophyl belonging to Prototheca, forming together with bacteria and fungi the micro flora of the mammary gland. The alga content of normal milk was signaled only in two farms (2.27%, respectively 1.21%, being established to 0.72%. In the case of mastitic milk the percentage of positive samples raised up to 3.3%, the isolating frequency being important only in one farm (9.6%, where were episodes of antibiotic resistant mastitis. The alga were well developed on gelose and Sabouraud agar, at 20-37°C, and their identification as Prototheca, was based on making evident the typical morphological elements, big sporangium (10-30μm containing 4-8 daughter cells.

  4. Comparison of solar-induced chlorophyll fluorescence, light-use efficiency, and process-based GPP models in maize.

    Science.gov (United States)

    Wagle, Pradeep; Zhang, Yongguang; Jin, Cui; Xiao, Xiangming

    2016-06-01

    Accurately quantifying cropland gross primary production (GPP) is of great importance to monitor cropland status and carbon budgets. Satellite-based light-use efficiency (LUE) models and process-based terrestrial biosphere models (TBMs) have been widely used to quantify cropland GPP at different scales in past decades. However, model estimates of GPP are still subject to large uncertainties, especially for croplands. More recently, space-borne solar-induced chlorophyll fluorescence (SIF) has shown the ability to monitor photosynthesis from space, providing new insights into actual photosynthesis monitoring. In this study, we examined the potential of SIF data to describe maize phenology and evaluated three GPP modeling approaches (space-borne SIF retrievals, a LUE-based vegetation photosynthesis model [VPM], and a process-based soil canopy observation of photochemistry and energy flux [SCOPE] model constrained by SIF) at a maize (Zea mays L.) site in Mead, Nebraska, USA. The result shows that SIF captured the seasonal variations (particularly during the early and late growing season) of tower-derived GPP (GPP_EC) much better than did satellite-based vegetation indices (enhanced vegetation index [EVI] and land surface water index [LSWI]). Consequently, SIF was strongly correlated with GPP_EC than were EVI and LSWI. Evaluation of GPP estimates against GPP_EC during the growing season demonstrated that all three modeling approaches provided reasonable estimates of maize GPP, with Pearson's correlation coefficients (r) of 0.97, 0.94, and 0.93 for the SCOPE, VPM, and SIF models, respectively. The SCOPE model provided the best simulation of maize GPP when SIF observations were incorporated through optimizing the key parameter of maximum carboxylation capacity (Vcmax). Our results illustrate the potential of SIF data to offer an additional way to investigate the seasonality of photosynthetic activity, to constrain process-based models for improving GPP estimates, and to

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

    Science.gov (United States)

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

    2014-12-01

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

  6. Toxic Effects of Ethyl Cinnamate on the Photosynthesis and Physiological Characteristics of Chlorella vulgaris Based on Chlorophyll Fluorescence and Flow Cytometry Analysis

    Directory of Open Access Journals (Sweden)

    Yang Jiao

    2015-01-01

    Full Text Available The toxic effects of ethyl cinnamate on the photosynthetic and physiological characteristics of Chlorella vulgaris were studied based on chlorophyll fluorescence and flow cytometry analysis. Parameters, including biomass, Fv/Fm (maximal photochemical efficiency of PSII, ФPSII (actual photochemical efficiency of PSII in the light, FDA, and PI staining fluorescence, were measured. The results showed the following: (1 The inhibition on biomass increased as the exposure concentration increased. 1 mg/L ethyl cinnamate was sufficient to reduce the total biomass of C. vulgaris. The 48-h and 72-h EC50 values were 2.07 mg/L (1.94–2.20 and 1.89 mg/L (1.82–1.97. (2 After 24 h of exposure to 2–4 mg/L ethyl cinnamate, the photosynthesis of C. vulgaris almost ceased, manifesting in ФPSII being close to zero. After 72 h of exposure to 4 mg/L ethyl cinnamate, the Fv/Fm of C. vulgaris dropped to zero. (3 Ethyl cinnamate also affected the cellular physiology of C. vulgaris, but these effects resulted in the inhibition of cell yield rather than cell death. Exposure to ethyl cinnamate resulted in decreased esterase activities in C. vulgaris, increased average cell size, and altered intensities of chlorophyll a fluorescence. Overall, esterase activity was the most sensitive variable.

  7. Evaluation the vigour of urban green lawn grown under long-term shade conditions by the use of chlorophyll fluorescence technique

    Directory of Open Access Journals (Sweden)

    Dąbrowski Piotr

    2015-09-01

    Full Text Available Unfavorable light conditions in urban areas are one of the most important cause of inappropriate grass communities condition. The possibility to detect the plant stress caused by shade is an important element in shaping the environment. The answer to following questions: what is the ability to detect the stress caused by shade in chosen lawn varieties of Perennial ryegrass by using the chlorophyll a fluorescence (O-J-I-P test and which of tested varieties has the best properties to create grasslands in reduced light conditions is the aim of this work. Two-factor experimental micro-plot was conducted with three varieties and three different shadowing variants. Chlorophyll a fluorescence measurements were provided and were compared to leaf density. Our results explored significant difference between selected varieties in the terms of their photosynthetic apparatus adaption to light conditions. During May, all tested varieties were characterized by the rise of all fluorescence curve points under lower light intensity. The largest changes under shade conditions were noticed for the variety ‘Taya’. During next months a declining trend of photosynthetic efficiency for this variety was observed. On the basis of our results, we assume that each variety has unique threshold and needs of light intensity.

  8. Effect of Different Norms of Under-Mulch-Drip Irrigation on Diurnal Changes of Photosynthesis and Chlorophyll Fluorescence Parameter in High Yield Cotton of Xinjiang

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wang-feng; REN Li-tong; WANG Zhen-lin; LI Shao-kun; GOU Ling; YU Songlie; CAO Lian-pu

    2003-01-01

    Under-mulch-drip irrigation is an advanced irrigation technique, which combines plastic-film-covered cultivation with drip irrigation. The influence of different norms of under-mulch-drip irrigation on di-urnal changes of photosynthetic rates and chlorophyll fluorescence parameters of cotton was studied, in orderto understand the physiological mechanisms of water-saving and high-yielding farming in Xinjiang. Results in-dicated that limited drip irrigation, which supplies 2/3 of 375 m3 ha-1 , the widely-used irrigation norm in cot-ton cultivation in Xinjiang, caused a water deficit in cotton field. Compared with the proper drip irrigation,the leaf photosynthetic rate under limited drip irrigation decreased during 9:00 to 11:00 a. m., and was sig-nificantly suppressed at midday, and then recovered afterwards. Using the chlorophyll fluorescence method,the absorption, transfer and transformation features of solar radiation by cotton leaf were investigated. Underlimited drip irrigation, the variable fluorescence (Fy) and primary light transfer efficiency of PSII (Fv/Fm)in cotton leaves were reduced because of the high light intensities and high temperatures at noon, and the de-crease in Xinluzao8 was greater than that in Xinluzao6. Therefore, it could be concluded that Xinluzao6 has ahigher drought-tolerance, and the Fv/Fm ratio could be used as a drought-resistance index for cotton.

  9. Effect of photosystem I inactivation on chlorophyll a fluorescence induction in wheat leaves: Does activity of photosystem I play any role in OJIP rise?

    Science.gov (United States)

    Zivcak, Marek; Brestic, Marian; Kunderlikova, Kristyna; Olsovska, Katarina; Allakhverdiev, Suleyman I

    2015-11-01

    Interpretation of the fast chlorophyll a fluorescence induction is still a subject of continuing discussion. One of the contentious issues is the influence of photosystem I (PSI) activity on the kinetics of the thermal JIP-phase of OJIP rise. To demonstrate this influence, we realized a series of measurements in wheat leaves subjected to PSI photoinactivation by the sequence of red saturation pulses (15,000 μmol photons m(-2) s(-1) for 0.3 s, every 10 s) applied in darkness. Such a treatment led to a moderate decrease of maximum quantum efficiency of PSII (by ~8%), but a strong decrease of the number of oxidizable PSI (by ~55%), which considerably limited linear electron transport and CO2 assimilation. Surprisingly, the PSI photoinactivation had low effects on OJIP kinetics of variable fluorescence. In particular, the amplitude of variable fluorescence of IP-step (ΔVIP), which has been considered to be a measure of PSI content, was not decreased, despite the low content of photooxidizable PSI. On the other hand, the slower relaxation of chlorophyll fluorescence after saturation pulse as well as the results of the double-hit method suggest that PSI inactivation treatment led to an increase of the fraction of QB-nonreducing PSII reaction centers. Our results somewhat challenge the mainstream interpretations of JIP-thermal phase, and at least suggest that the IP amplitude cannot serve to estimate reliably the PSI content or the PSI to PSII ratio. Moreover, these results recommend the use of the novel method of PSI inactivation, which might help clarify some important issues needed for the correct understanding of the OJIP fluorescence rise. PMID:26388470

  10. Signal enhanced holographic fluorescence microscopy with guide-star reconstruction

    Science.gov (United States)

    Jang, Changwon; Clark, David C.; Kim, Jonghyun; Lee, Byoungho; Kim, Myung K.

    2016-01-01

    We propose a signal enhanced guide-star reconstruction method for holographic fluorescence microscopy. In the late 00’s, incoherent digital holography started to be vigorously studied by several groups to overcome the limitations of conventional digital holography. The basic concept of incoherent digital holography is to acquire the complex hologram from incoherent light by utilizing temporal coherency of a spatially incoherent light source. The advent of incoherent digital holography opened new possibility of holographic fluorescence microscopy (HFM), which was difficult to achieve with conventional digital holography. However there has been an important issue of low and noisy signal in HFM which slows down the system speed and degrades the imaging quality. When guide-star reconstruction is adopted, the image reconstruction gives an improved result compared to the conventional propagation reconstruction method. The guide-star reconstruction method gives higher imaging signal-to-noise ratio since the acquired complex point spread function provides optimal system-adaptive information and can restore the signal buried in the noise more efficiently. We present theoretical explanation and simulation as well as experimental results.

  11. Signal enhanced holographic fluorescence microscopy with guide-star reconstruction

    Science.gov (United States)

    Jang, Changwon; Clark, David C.; Kim, Jonghyun; Lee, Byoungho; Kim, Myung K.

    2016-01-01

    We propose a signal enhanced guide-star reconstruction method for holographic fluorescence microscopy. In the late 00’s, incoherent digital holography started to be vigorously studied by several groups to overcome the limitations of conventional digital holography. The basic concept of incoherent digital holography is to acquire the complex hologram from incoherent light by utilizing temporal coherency of a spatially incoherent light source. The advent of incoherent digital holography opened new possibility of holographic fluorescence microscopy (HFM), which was difficult to achieve with conventional digital holography. However there has been an important issue of low and noisy signal in HFM which slows down the system speed and degrades the imaging quality. When guide-star reconstruction is adopted, the image reconstruction gives an improved result compared to the conventional propagation reconstruction method. The guide-star reconstruction method gives higher imaging signal-to-noise ratio since the acquired complex point spread function provides optimal system-adaptive information and can restore the signal buried in the noise more efficiently. We present theoretical explanation and simulation as well as experimental results. PMID:27446653

  12. Gas exchange and chlorophyll fluorescence of pea (Pisum sativum L.) plants in response to ambient ozone at a rural site in Egypt

    International Nuclear Information System (INIS)

    Egyptian pea cultivars (Pisum sativum L. cultivars Little Marvel, Perfection and Victory) grown in open-top chambers were exposed to either charcoal-filtered (FA) or non-filtered air (NF) for five consecutive years (2009–2013) at a rural site in northern Egypt. Net photosynthetic rates (PN), stomatal conductance (gs), intercellular CO2 (Ci) and chlorophyll fluorescence were measured. Ozone (O3) was found to be the most prevalent pollutant common at the rural site and is suspected to be involved in the alteration of the physiological parameters measured in the present investigation. PN of different cultivars were found to respond similarly; decreases of 23, 29 and 39% were observed in the cultivars Perfection, Little Marvel and Victory, respectively (averaged over the five years) due to ambient O3. The maximum impairment in PN was recorded in the cultivar Victory (46%) in 2013 when the highest O3 levels were recorded (90 nL L−1). The average stomatal conductance decreased by 20 and 18% in the cultivars Little Marvel and Perfection, respectively, while the average stomatal conductance increased on average by 27% in the cultivar Victory. A significant correlation was found between PN and Ci, indicating the importance of non-stomatal limitations of photosynthesis, especially in the cultivar Victory. The PN vs. Ci curves were fitted to a non-rectangular hyperbolic model. The actual quantum yield (ΦPSII) and photochemical quenching coefficient (qP) were significantly decreased in the leaves of plants exposed to NF air. Non-photochemical quenching (NPQ) was increased in all cultivars. Exposure to NF air caused reductions in chlorophyll (Chl a) of 19, 16 and 30% in the Little Marvel, Perfection and Victory cultivars, respectively. - Highlights: • Ozone (O3) concentrations recorded were within the ranges of phytotoxicity. • O3 has a clear influence on the physiological parameters. • O3 decreased Photosynthetic rates, chlorophyll fluorescence parameters. • The

  13. Effects of Chilling Stress on Photosynthetic Rate and Chlorophyll Fluorescence Parameter in Seedlings of Two Rice Cultivars Differing in Cold Tolerance

    Institute of Scientific and Technical Information of China (English)

    WANG Guo-li; GUO Zhen-fei

    2005-01-01

    A cold-tolerant cultivar, Xiangnuo 1, and a cold-sensitive cultivar, IR50, were used to study the influence of chilling on photosynthetic rate and chlorophyll fluorescence parameters in rice seedlings. The photosynthetic rates declined dramatically during chilling, and decreased by 48.7% and 67.5% in Xiangnuo 1 and IR50 seedlings, respectively, after being subjected to chilling treatment for two days. Chlorophyll fluorescence measurements showed that relatively higher qP and qNP in Xiangnuo 1 were maintained to dissipate the redundant excitation energy and protect the reaction centers from chill injury; accordingly, redundant excitation energy accumulated less in the reaction centers, and antenna systems were less injured by chilling in Xiangnuo 1. On the contrary, in IR50, qP and qNP declined rapidly while Ex increased, as the chilling persisted. This result indicated that the reaction centers and antenna systems in IR50 were damaged severely by chilling, which led to the lower photosynthetic rate.

  14. Stress tolerance and stress-induced injury in crop plants measured by chlorophyll fluorescence in vivo: chilling, freezing, ice cover, heat, and high light.

    Science.gov (United States)

    Smillie, R M; Hetherington, S E

    1983-08-01

    The proposition is examined that measurements of chlorophyll fluorescence in vivo can be used to monitor cellular injury caused by environmental stresses rapidly and nondestructively and to determine the relative stress tolerances of different species. Stress responses of leaf tissue were measured by F(R), the maximal rate of the induced rise in chlorophyll fluorescence. The time taken for F(R) to decrease by 50% in leaves at 0 degrees C was used as a measure of chilling tolerance. This value was 4.3 hours for chilling-sensitive cucumber. In contrast, F(R) decreased very slowly in cucumber leaves at 10 degrees C or in chilling-tolerant cabbage leaves at 0 degrees C. Long-term changes in F(R) of barley, wheat, and rye leaves kept at 0 degrees C were different in frost-hardened and unhardened material and in the latter appeared to be correlated to plant frost tolerance. To simulate damage caused by a thick ice cover, wheat leaves were placed at 0 degrees C under N(2). Kharkov wheat, a variety tolerant of ice encapsulation, showed a slower decrease in F(R) than Gatcher, a spring wheat. Relative heat tolerance was also indicated by the decrease in F(R) in heated leaves while changes in vivo resulting from photoinhibition, ultraviolet radiation, and photobleaching can also be measured. PMID:16663118

  15. [Effects of exogenous Ca2+ on morphological and photosynthetic characteristics and chlorophyll fluorescent parameters of squash seedlings under high temperature and strong light stress].

    Science.gov (United States)

    Qin, Shu-hao; Li, Ling-ling; Chen, Na-na

    2010-11-01

    Taking squash (Cucurbita pepo L.) variety Alan as test object, this paper studied the effects of exogenous Ca2+ on the morphological and photosynthetic characteristics and chlorophyll fluorescent parameters of squash seedlings under the cross-stress of high temperature and strong light. Under the stress, applying 5-20 mmol x L(-1) of Ca2+ increased the plant height, leaf area, chlorophyll and carotenoid contents, photosynthetic rate (Pn), stoma conductance (Gs), transpiration rate (Tr), maximal PS II efficiency (Fv/Fm), actual PS II efficiency (phi(PS II)), and photochemical queching coefficient (q(P)), and decreased the intercellular CO2 concentration (Ci) and non-photochemical fluorescence quenching coefficient (NPQ), suggesting that this application of exogenous Ca2+ could effectively mitigate the damage of high temperature and strong light stress on the squash seedlings leaf, and make it keep more rapid photosynthetic electron transfer rate and higher PS II electron transfer activity. Among the treatments of applying Ca2+, 10 mmol Ca2+ x L(-1) had the best effect. When the Ca2+ application rate exceeded 40 mmol x L(1), no mitigation effect was observed on the high temperature and strong light stress.

  16. Monitoring Wnt Signaling in Zebrafish Using Fluorescent Biosensors.

    Science.gov (United States)

    Facchinello, Nicola; Schiavone, Marco; Vettori, Andrea; Argenton, Francesco; Tiso, Natascia

    2016-01-01

    In this chapter, we are presenting methods to monitor and quantify in vivo canonical Wnt signaling activities at single-cell resolution in zebrafish. Our technology is based on artificial enhancers, obtained by polymerization of TCF binding elements, cloned upstream to ubiquitous or tissue-specific promoters. The different promoter/enhancer combinations are used to drive fluorescent protein reporter constructs integrated in the zebrafish germline by microinjection of fertilized zebrafish eggs. Fish with a single integration site are selected by Mendelian analysis of fluorescent carriers, and heterozygous offspring are used to monitor and quantify canonical Wnt activities. Open source public domain software such as ImageJ/Fiji is used to calculate the integrated densities in the region of interest and compare the effect of experimental conditions on control and treated animals. PMID:27590154

  17. RNA signal amplifier circuit with integrated fluorescence output.

    Science.gov (United States)

    Akter, Farhima; Yokobayashi, Yohei

    2015-05-15

    We designed an in vitro signal amplification circuit that takes a short RNA input that catalytically activates the Spinach RNA aptamer to produce a fluorescent output. The circuit consists of three RNA strands: an internally blocked Spinach aptamer, a fuel strand, and an input strand (catalyst), as well as the Spinach aptamer ligand 3,5-difluoro-4-hydroxylbenzylidene imidazolinone (DFHBI). The input strand initially displaces the internal inhibitory strand to activate the fluorescent aptamer while exposing a toehold to which the fuel strand can bind to further displace and recycle the input strand. Under a favorable condition, one input strand was able to activate up to five molecules of the internally blocked Spinach aptamer in 185 min at 30 °C. The simple RNA circuit reported here serves as a model for catalytic activation of arbitrary RNA effectors by chemical triggers.

  18. Design and daytime performance of laser-induced fluorescence spectrum lidar for simultaneous detection of multiple components, dissolved organic matter, phycocyanin, and chlorophyll in river water.

    Science.gov (United States)

    Saito, Yasunori; Kakuda, Kei; Yokoyama, Mizuho; Kubota, Tomoki; Tomida, Takayuki; Park, Ho-Dong

    2016-08-20

    In this work, we developed mobile laser-induced fluorescence spectrum (LIFS) lidar based on preliminary experiments on the excitation emission matrix of a water sample and a method for reducing solar background light using the synchronous detection technique. The combination of a UV short-pulse laser (355 nm, 6 ns) for fluorescence excitation with a 10-100 ns short-time synchronous detection using a gated image-intensified multi-channel CCD of the fluorescence made the LIFS lidar operation possible even in daytime. The LIFS lidar with this construction demonstrated the potential of natural river/lake water quality monitoring at the Tenryu River/Lake Suwa. Three main components in the fluorescence data of the water, dissolved organic matter, phycocyanin, and chlorophyll, were extracted by spectral analysis using the standard spectral functions of these components. Their concentrations were estimated by adapting experimentally calibrated data. Results of long-term field observations using our LIFS lidar from 2010 to 2012 show the necessity of simultaneous multi-component detection to understand the natural water environment. PMID:27556995

  19. Effect of Different Light Qualities on Growth, Pigment Content, Chlorophyll Fluorescence, and Antioxidant Enzyme Activity in the Red Alga Pyropia haitanensis (Bangiales, Rhodophyta)

    Science.gov (United States)

    2016-01-01

    Spectral light changes evoke different morphogenetic and photosynthetic responses that can vary among different algae species. The aim of this study is to investigate the photosynthetic characteristics of the red macroalgae grown under different spectrum environments. In this study, Pyropia haitanensis were cultured under blue, red, and green LED and fluorescent tubes light. The growth rate, photopigment composition, chlorophyll fluorescence, and antioxidative enzymes activities in different light spectrums were investigated. The results revealed that growth rate was significantly higher in the thalli grown under blue, green, and fluorescent tubes light. Contents of Chl a and phycobiliprotein in red light were lower among all the growth conditions. Furthermore, a striking increase in SOD and CAT activity was observed in red light treatment along with the NPQ increase. The results revealed that the photosynthetic efficiency and increased growth rate of P. haitanensis benefitted from light spectrums such as blue, green, and fluorescent tubes light by pigment composition and photochemical efficiency manipulation, whereas red light has disadvantageous effects. Accordingly, the results for improving quality and the economic yield of algae species in some extent and the combination of different wavelengths could allow better economic resource exploitation. PMID:27642603

  20. Effect of Different Light Qualities on Growth, Pigment Content, Chlorophyll Fluorescence, and Antioxidant Enzyme Activity in the Red Alga Pyropia haitanensis (Bangiales, Rhodophyta).

    Science.gov (United States)

    Wu, Huanyang

    2016-01-01

    Spectral light changes evoke different morphogenetic and photosynthetic responses that can vary among different algae species. The aim of this study is to investigate the photosynthetic characteristics of the red macroalgae grown under different spectrum environments. In this study, Pyropia haitanensis were cultured under blue, red, and green LED and fluorescent tubes light. The growth rate, photopigment composition, chlorophyll fluorescence, and antioxidative enzymes activities in different light spectrums were investigated. The results revealed that growth rate was significantly higher in the thalli grown under blue, green, and fluorescent tubes light. Contents of Chl a and phycobiliprotein in red light were lower among all the growth conditions. Furthermore, a striking increase in SOD and CAT activity was observed in red light treatment along with the NPQ increase. The results revealed that the photosynthetic efficiency and increased growth rate of P. haitanensis benefitted from light spectrums such as blue, green, and fluorescent tubes light by pigment composition and photochemical efficiency manipulation, whereas red light has disadvantageous effects. Accordingly, the results for improving quality and the economic yield of algae species in some extent and the combination of different wavelengths could allow better economic resource exploitation. PMID:27642603

  1. Comparison of Measurements and FluorMOD Simulations for Solar Induced Chlorophyll Fluorescence and Reflectance of a Corn Crop under Nitrogen Treatments [SIF and Reflectance for Corn

    Science.gov (United States)

    Middleton, Elizabeth M.; Corp, Lawrence A.; Campbell, Petya K. E.

    2007-01-01

    The FLuorescence Explorer (FLEX) satellite concept is one of six semifinalist mission proposals selected in 2006 for pre-Phase studies by the European Space Agency (ESA). The FLEX concept proposes to measure passive solar induced chlorophyll fluorescence (SIF) of terrestrial ecosystems. A new spectral vegetation Fluorescence Model (FluorMOD) was developed to include the effects of steady state SIF on canopy reflectance. We used our laboratory and field measurements previously acquired from foliage and canopies of corn (Zea mays L.) under controlled nitrogen (N) fertilization to parameterize and evaluate FluorMOD. Our data included biophysical properties, fluorescence (F) and reflectance spectra for leaves; reflectance spectra of canopies and soil; solar irradiance; plot-level leaf area index; and canopy SIF emissions determined using the Fraunhofer Line Depth principal for the atmospheric telluric oxygen absorption features at 688 nm (O2-beta) and 760 nm (O2-alpha). FluorMOD simulations implemented in the default "look-up-table" mode did not reproduce the observed magnitudes of leaf F, canopy SIF, or canopy reflectance. However, simulations for all of these parameters agreed with observations when the default FluorMOD information was replaced with measurements, although N treatment responses were underestimated. Recommendations were provided to enhance FluorMOD's potential utility in support of SIF field experiments and studies of agriculture and ecosystems.

  2. [Effects of plastic film mulching and rain harvesting modes on chlorophyll fluorescence characteristics, yield and water use efficiency of dryland maize].

    Science.gov (United States)

    Li, Shang-Zhong; Fan, Ting-Lu; Wang, Yong; Zhao, Gang; Wang, Lei; Tang, Xiao-Ming; Dang, Yi; Zhao, Hui

    2014-02-01

    The differences on chlorophyll fluorescence parameters, yield and water use efficiency of dryland maize were compared among full plastic film mulching on double ridges and planting in catchment furrows (FFDRF), half plastic film mulching on double ridges and planting in catchment furrows (HFDRF), plastic film mulching on ridge and planting in film-side (FS), and flat planting with no plastic film mulching (NM) under field conditions in dry highland of Loess Plateau in 2007-2012. The results showed that fluorescence yield (Fo), the maximum fluorescence yield (Fm), light-adapted fluorescence yield when PS II reaction centers were totally open (F), light-adapted fluorescence yield when PS II reaction centers closed (Fm'), the maximal photochemical efficiency of PS II (Fv/Fm), the actual photochemical efficiency of PS II in the light (Phi PS II), the relative electron transport rate (ETR), photochemical quenching (qP) and non-photochemical quenching (qN) in maize leaves of FFDRF were higher than that of control (NM), and the value of 1-qP was lower than that of control, at 13:00, chlorophyll fluorescence parameters values of FFDRF was significantly higher than control, which were increased by 5.3%, 56.8%, 10.7%, 36.3%, 23.6%, 56.7%, 64.4%, 45.5%, 23.6% and -55.6%, respectively, compared with the control. Yield and water use efficiency of FFDRF were the highest in every year no matter dry year, normal year, humid year and hail disaster year. Average yield and water use efficiency of FFDRF were 12,650 kg x hm(-2) and 40.4 kg x mm(-1) x hm(-2) during 2007-2012, increased by 57.8% and 61.6% compared with the control, respectively, and also significantly higher compared with HFDRF and PS. Therefore, it was concluded that FFDRF had significantly increased the efficiency of light energy conversion and improved the production capacity of dryland maize. PMID:24830246

  3. Photo-electric effects on chlorophyll fluorescence of photosystem II in vivo. Kinetics in absence and presence of valinomycin

    NARCIS (Netherlands)

    Vredenberg, W.J.; Bulychev, A.A.

    2003-01-01

    Fluorescence induction curves (F(t)) in low intensity 1s light pulses have been measured in leaf discs in the presence and absence of valinomycin (VMC). Addition of VMC causes: (i) no effect on the initial fluorescence level Fo and the initial (O-J) phase of F(t) in the 0.01-1 ms time range. (ii) An

  4. The chlorophyll a fluorescence induction curve in the green microalga Haematococcus pluvialis: further insight into the nature of the P-S-M fluctuation and its relationship with the "low-wave" phenomenon at steady-state.

    Science.gov (United States)

    Fratamico, Anthony; Tocquin, Pierre; Franck, Fabrice

    2016-06-01

    Chlorophyll fluorescence is an information-rich signal which provides an access to the management of light absorbed by PSII. A good example of this is the succession of fast fluorescence fluctuations during light-induced photosynthetic induction after dark-adaptation. During this period, the fluorescence trace exhibits several inflexion points: O-J-I-P-S-M-T. Whereas the OJIP part of this kinetics has been the subject of many studies, the processes that underly the PSMT transient are less understood. Here, we report an analysis of the PSMT phase in the green microalga Haematococcus pluvialis in terms of electron acceptors and light use by photochemistry, fluorescence and non-photochemical quenching (NPQ). We identify additional sub-phases between P and S delimited by an inflexion point, that we name Q, found in the second time scale. The P-Q phase expresses a transient photochemical quenching specifically due to alternative electron transport to oxygen. During the transition from Q to S, the NPQ increases and then relaxes during the S-M phase in about 1 min. It is suggested that this transient NPQ observed during induction is a high energy state quenching (qE) dependent on the alternative electron transport to molecular oxygen. We further show that this NPQ is of the same nature than the NPQ, known as the low-wave phenomenon, which is transiently observed after a saturating light pulse given at steady-state. In both cases, the NPQ is oxygen-dependent. This NPQ is observed at external pH 6.0, but not at pH 7.5, which seems correlated with faster saturation of the PQ pool at pH 6.0. PMID:26980274

  5. Varietal differences in photosynthetic characters and chlorophyll fluorescence induction kinetics parameters among intergeneric progeny derived from Oryza×Sorghum, its parents, and hybrid rice

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A comparative study on the photosynthetic parameters among intergeneric progenies derived from Oryza sativa L.×Sorghum vulgare L., its maternal parent Gui 630 and commercial 3-line hybrid rice Shanyou 63 in pot experiment in greenhouse was conducted. The morphological and photosynthetic characters of canopy leaves and chlorophyll fluorescence kinetic parameters including Fv/Fm, Fv/F0, photochemical quenching coefficient and non-photochemical coefficient of canopy leaves of 3 varieties were measured. The results showed the progeny, Yuanyou 1, derived from an intergeneric cross of rice and sorghum possesses better canopy spatial architecture with thicker, heavier and bigger canopy leaf than its maternal parent Gui 630. Higher photosynthetic rate due to higher chlorophyll content, higher primary energy transformation efficiency, potential of PSII and non-photochemical quenching coefficient (qE) were also measured in Yuanyou 1. These explain partly why the intergeneric progeny has higher biomass production, and better tolerance to adverse conditions and higher field yields even under stress conditions.

  6. Varietal differences in photosynthetic characters and chlorophyll fluorescence induction kinetics parameters among intergeneric progeny derived from Oryza×Sorghum, its parents, and hybrid rice

    Institute of Scientific and Technical Information of China (English)

    KatsuyoshiShimizu; 唐建军; 陈欣

    2002-01-01

    A comparative study on the photosynthetic parameters among intergeneric progenies derived from Oryza sativa L.× Sorghum vulgare L. , its maternal parent Gui 630 and commercial 3-line hybrid rice Shanyou 63 in pot experiment in greenhouse was conducted. The morphological and photosynthetic characters of canopy leaves and chlorophyll fluorescence kinetic pm'mneters including Fv/Fm, Fv/F0, photochemical quenching coefficient and non-photochemical coefficient of canopy leaves of 3 varieties were measured. The results showed the progeny, Yuanyou 1, derived from an intergeneric cross of rice and sorghum possesses better canopy spatial architecture with thicker, heavier and bigger canopy leaf than its maternal parent Gui 630.Higher photosynthetic rate due to higher chlorophyll content, higher primary energy transformation efficiency,potential of PSII and non-photochemieal quenching coefficient (qE) were also measured in Yuanyou 1. These explain partly why the intergeneric progeny has higher biomass production, and better tolerance to adverse conditions and higher field yields even under stress conditions.

  7. Effects of sand burial on biomass, chlorophyll fluores-cence and extracellular polysaccharides of man-made cyanobacterial crusts under experimental conditions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Soil cyanobacterial crusts occur throughout the world, especially in the semiarid and arid regions. It always encounters sand burial, which is an important feature of mobile sand dunes. A greenhouse study was conducted to determine the effects of sand burial on biomass, chlorophyll fluorescence and extracellular polysaccharides of man-made cyanobacterial crusts in six periods of time (0, 5, 10, 15, 20 and 30 d after burying) and at five depths (0, 0.2, 0.5, 1 and 2cm). The results indicated that with the increase of the burial time and burial depth extracellular polysaccharides content and Fv/Fm decreased correspondingly and there were no significant differences between 20 and 30 burial days under dif-ferent burial depths. The degradation of chlorophyll a content appeared only at 20 and 30 burial days and there was also no significant difference between them under different burial depths. It was also observed a simultaneous decrease of the values of the Fv/Fm and the content of extracellular poly-saccharides happened in the crusted cyanobacterium Microcoleus vaginatus Gom. It may suggest that there exists a relationship between extracellular polysaccharides and recovery of the activity of pho-tosystem II (PS II) after rehydration.

  8. Photosynthetic activity, chlorophyll-fluorescence parameters and pigment content of differently damaged spruces at the Schoellkopf (Northern Black Forest). Photosyntheseaktivitaet, Chlorophyllfluoreszenzparameter und Pigmentgehalt unterschiedlich geschaedigter Fichten am Schoellkopf (Nordschwarzwald)

    Energy Technology Data Exchange (ETDEWEB)

    Lichtenthaler, H.K.; Rinderle, U.; Burkart, S.; Hak, R. (Karlsruhe Univ. (T.H.) (Germany, F.R.). Botanisches Inst. 2)

    1990-04-01

    At the new PEF-site Schoellkopf (840 m above see level) various physiological parameters were determined from one relatively healthy (tree No. 13) and two differently damaged spruces (tree No. 17 and 2): The netto assimilation rate P{sub N} (on a needle area and a chlorophyl basis), respiration, transpiration and stomata conductivity (gH{sub 2}O), the content of photosynthetic pigments (chlorophyll a+b, carotenoids x+c), the pigment ratios (a/b; a+b/x+c) and various parameters of the in vivo chlorophyll fluorescence (Rfd-values at 690 and 730 nm, the fluorescence ratio F690/F730; quenching-coefficients qP and qNP, the ratio Fm/Fo and Fv/Fm). Stress and damage are preferentially indicated by lower values of the chlorophyll content, the pigment ratio a+b/x+c, the assimilation rate P{sub N} and the hight of the saturation pulse spikes (g-h) as well as increased values of the coefficient qNP and the fluorescence ratio F690/F730. The differential dynamics of the chlorophyll content and the photosynthetic activity between the needles of 'healthy' and damaged spruces during the year 1989 (4 sampling dates) are presented. (orig.).

  9. Toxic effects of amoxicillin on the photosystem II of Synechocystis sp. characterized by a variety of in vivo chlorophyll fluorescence tests

    International Nuclear Information System (INIS)

    Amoxicillin is one of the widely used antibiotics of environmental concern. This study shows that amoxicillin has toxic effects on the photosynthesis of Synechocystis sp. Its inhibitory effects on photosystem II (PSII) of Synechocystis sp. were investigated by using a variety of in vivo chlorophyll fluorescence tests. The inhibitory effects of amoxicillin on PSII activity of Synechocystis sp. are concentration-dependent. Amoxicillin exposure leads to slowing down of electron transport on both donor side and acceptor side and causes accumulation of P680+. QA- reoxidation test revealed that amoxicillin hinders electron transfer from QA- to QB/QB- and more QA- is oxidized through S2(QAQB)- charge recombination. Analysis of PSII heterogeneity demonstrated that an exposure to amoxicillin increases the proportion of inactive PSII (PSIIX) centers and the proportion of PSII centers with small antenna (PSIIβ). These changes finally result in deterioration of full photosynthesis performance

  10. Effects of Low Temperature Stress and INA Bacteria on Chlorophyll a Fluorescence Induction Kinetics in Young Fruit of Two Apricot Cultivars

    Institute of Scientific and Technical Information of China (English)

    YANG Jian-min; MENG Qing-rui; PENG Wei-xiu; WANG Xue-dong; ZHANG Yuan-hui; SUN Fu-zai; ZHAO Ting-chang; LI Shao-hua

    2002-01-01

    Effects of low temperature and INA bacteria on the change of chlorophyll a fluorescence inyoung fruit from two apricot cultivars were investigated. Low temperature decreased the potential activity(Fv/Fo) ,conversion efficiency of primary light energy (Fv/Fm)of PS Ⅱ and photochemical quenching (qP) inyoung fruit of two apricot cultivars. Low temperature enhanced non-photochemical quenching qN, decreasingthe quantum yield of photosynthetic electron transfer. The presence of ice nucleating active (INA) bacteria in-tensified the effects of low temperature, raised the injury temperature threshold from - 4℃ to - 2 - - 3℃.INA bacteria can be a factor to induce frost susceptibility of apricot fruit. The amount of damaged PS Ⅱ activi-ty center was related to apricot fruit size and cultivar.

  11. Chlorophyll Fluorescence in Partially Defoliated Grape Plants (Vitis vinifera L. cv. Chardonnay / Fluorescencia de la Clorofila en Plantas de Uva (Vitis vinifera L. cv. Chardonnay Defoliadas Parcialmente

    Directory of Open Access Journals (Sweden)

    Peña Olmos Jaime Ernesto

    2013-08-01

    Full Text Available The chlorophyll content and fluorescence weredetermined in five-year-old grape plants (Vitis vinifera L. cv.Chardonnay that were subjected to early partial defoliation,in Villa de Leyva, Colombia. The experimental design wascompletely randomized, consisting of two treatments (50%defoliation and control, each with four replications of 35 plants. Every two weeks, one of every two recently-emerged leaves was removed from the non-control plants. The determination of total chlorophyll content was carried out on six leaves per plant using a CCM-200 Plus chlorophyll meter, while chlorophyll fluorescence measurements were taken with one darkadapted leaf per plant using a Junior-PAM fluorometer. Initial fluorescence (Fo, maximum fluorescence (Fm, terminal fluorescence (Ft, variable fluorescence (Fv, electron transport rate (ETR, maximum photochemical quantum yield of PSII (Fv/ Fm, effective photochemical quantum yield of photosystem II (Y(II, photochemical fluorescence quenching coefficient (qP, two non-photochemical quenching coefficients (qN and NPQ,quantum yield of light-induced non-photochemical fluorescence quenching (Y(NPQ, and quantum yield of non-light-induced non-photochemical quenching (Y(NO were measured. The chlorophyll concentration index showed higher values in the defoliated plants. There were no significant differences for the values of Fm, Ft and Fv. Fo was higher in the defoliated plants, while ETR, Fv/Fm and Y(II showed higher values in the control plants. It is evident that a reduction in leaf area modifies thepartitioning of excitation energy destined for photochemicaland non-photochemical processes, thus directly influencing the photosynthetic process of the plants evaluated. / Utilizando un diseño completamente aleatorizado,con dos tratamientos (defoliación al 50% y control y cuatrorepeticiones de 35 plantas cada una, se determinó el contenido y la fluorescencia de la clorofila en plantas de uva, sometidas a defoliación parcial

  12. Gas exchange and chlorophyll fluorescence of pea (Pisum sativum L.) plants in response to ambient ozone at a rural site in Egypt

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, I.M.; Basahi, J.M. [Air Pollution Laboratory (APL), Centre of Excellence in Environmental Studies (CEES), King Abdulaziz University, P. O. Box 80216, Jeddah 21589 (Saudi Arabia); Hassan, I.A., E-mail: ihassan_eg@yahoo.com [Air Pollution Laboratory (APL), Centre of Excellence in Environmental Studies (CEES), King Abdulaziz University, P. O. Box 80216, Jeddah 21589 (Saudi Arabia); Department of Botany, Faculty of Science, Alexandria University, 21526 El Shatby, Alexandria (Egypt)

    2014-11-01

    Egyptian pea cultivars (Pisum sativum L. cultivars Little Marvel, Perfection and Victory) grown in open-top chambers were exposed to either charcoal-filtered (FA) or non-filtered air (NF) for five consecutive years (2009–2013) at a rural site in northern Egypt. Net photosynthetic rates (P{sub N}), stomatal conductance (g{sub s}), intercellular CO{sub 2} (C{sub i}) and chlorophyll fluorescence were measured. Ozone (O{sub 3}) was found to be the most prevalent pollutant common at the rural site and is suspected to be involved in the alteration of the physiological parameters measured in the present investigation. P{sub N} of different cultivars were found to respond similarly; decreases of 23, 29 and 39% were observed in the cultivars Perfection, Little Marvel and Victory, respectively (averaged over the five years) due to ambient O{sub 3}. The maximum impairment in P{sub N} was recorded in the cultivar Victory (46%) in 2013 when the highest O{sub 3} levels were recorded (90 nL L{sup −1}). The average stomatal conductance decreased by 20 and 18% in the cultivars Little Marvel and Perfection, respectively, while the average stomatal conductance increased on average by 27% in the cultivar Victory. A significant correlation was found between P{sub N} and C{sub i}, indicating the importance of non-stomatal limitations of photosynthesis, especially in the cultivar Victory. The P{sub N} vs. Ci curves were fitted to a non-rectangular hyperbolic model. The actual quantum yield (Φ{sub PSII}) and photochemical quenching coefficient (qP) were significantly decreased in the leaves of plants exposed to NF air. Non-photochemical quenching (NPQ) was increased in all cultivars. Exposure to NF air caused reductions in chlorophyll (Chl a) of 19, 16 and 30% in the Little Marvel, Perfection and Victory cultivars, respectively. - Highlights: • Ozone (O{sub 3}) concentrations recorded were within the ranges of phytotoxicity. • O{sub 3} has a clear influence on the physiological

  13. EFFECT OF Cu AND Mn TOXICITY ON CHLOROPHYLL FLUORESCENCE AND GAS EXCHANGE IN RICE AND SUNFLOWER UNDER DIFFERENT LIGHT INTENSITIES

    Directory of Open Access Journals (Sweden)

    Hajiboland R.

    2007-06-01

    Full Text Available Copper (Cu and manganese (Mn are essential micronutrients for plants, but toxic at high concentrations. Responses of rice (Oryza sativa L. and sunflower (Helianthus annuus L. to toxic concentrations of Mn and Cu (up to 100 μM were studied under three light intensities including low (LL, PPFD=100, intermediate (IL, PPFD=500 and high (HL, PPFD=800 light intensities in hydroponic medium. Rice plants showed higher susceptibility than sunflower to both heavy metals concerning dry matter of shoot and root. Growing under higher light intensity strengthened the effect of Cu toxicity while ameliorated that of Mn, the latter was attributed to the lower Mn accumulation of HL plants in both shoot and root. Chlorophyll content of leaves was influenced negatively only by Cu treatment and that at the highest concentration in the medium (100 μM. Similar with growth results, reduction of net assimilation rate (A was higher in HL than LL plants treated by excess Cu, but in contrast to growth response, reduction was more prominent in sunflower than rice. Excess Mn-induced reduction of A was similar between LL and HL plants and was greater in sunflower than rice. Reduction of A was partly attributable to stomatal limitation, but non-stomatal mechanisms were also involved in this reduction. Copper and Mn treatment did not change the optimal quantum efficiency of PSII in dark-adapted chloroplasts (Fv/Fm ratio, but Fv/F0 was influenced particularly by Cu treatment, the reduction was higher in rice than sunflower and in HL compared to LL plants. Regarding excess Cu and Mn-mediated alterations in chlorophyll concentration, Fv/F0 and Tm values, it was suggested that, Cu and Mn toxicity depress the leaf photosynthetic capacity primarily by causing a significant alteration of the composition and functional competence of the photosynthetic units rather a reduction in the number of photosynthetic units (PSUs per unit leaf area.

  14. Rapid chlorophyll a fluorescence transient of Lemna gibba leaf as an indication of light and hydroxylamine effect on photosystem II activity.

    Science.gov (United States)

    Dewez, David; Ali, Nadia Ait; Perreault, François; Popovic, Radovan

    2007-05-01

    Rapid chlorophyll fluorescence transient induced by saturating flash (3000 micromol of photons m-2 s-1) was investigated when Lemna gibba had been exposed to light (100 micromol of photons m-2 s-1) causing the Kautsky effect or in low light intensity unable to trigger PSII photochemistry. Measurements were made by using, simultaneously, a pulse amplitude modulated fluorometer and plant efficiency analyzer system, either on non-treated L. gibba leaf or those treated with different concentrations of hydroxylamine (1-50 mM) causing gradual inhibition of the water splitting system. When any leaf was exposed to continuous light during the Kautsky effect, a rapid fluorescence transient may reflect current activity of photosystem II within the photosystem II complex. Under those conditions, a variation of transition steps appearing over time was related to a drastic change to the photosystem II functional properties. This value indicated that the energy dissipation through non-photochemical pathways was undergoing extreme change. The change of rapid fluorescence transient, induced under continuous light, when compared to those obtained under very low light intensity, confirmed the ability of photosystem II to be capable to undergo rapid adaptation lasting about two minutes. When the water splitting system was inhibited and electron donation partially substituted by hydroxylamine, the adaptation ability of photosystem II to different light conditions was lost. In this study, the change of rapid fluorescence kinetic and transient appearing over time was shown to be a good indication for the change of the functional properties of photosystem II induced either by light or by hydroxylamine. PMID:17487305

  15. The impact of cell-specific absorption properties on the correlation of electron transport rates measured by chlorophyll fluorescence and photosynthetic oxygen production in planktonic algae.

    Science.gov (United States)

    Blache, Ulrich; Jakob, Torsten; Su, Wanwen; Wilhelm, Christian

    2011-08-01

    Photosynthesis-irradiance (P-E)-curves describe the photosynthetic performance of autotrophic organisms. From these P-E-curves the photosynthetic parameters α-slope, P(max), and E(k) can be deduced which are often used to characterize and to compare different organisms or organisms in acclimation to different environmental conditions. Particularly, for in situ-measurements of P-E curves of phytoplankton the analysis of variable chlorophyll fluorescence proved its potential as a sensitive and rapid method. By using Chlorella vulgaris (Trebouxiophyceae), Nannochloropsis salina (Eustigmatophyceae), Skeletonema costatum and Cyclotella meneghiniana (Bacillariophyceae), the present study investigated the influence of cellular bio-optical properties on the correlation of the photosynthetic parameters derived from fluorescence-based P-E-curves with photosynthetic parameters obtained from the measurement of oxygen evolution. It is demonstrated that small planktonic algae show a wide range of cellular absorptivity which was subject to species-specifity, growth stage and environmental conditions, e.g. nutrient limitation. This variability in bio-optical properties resulted in a great deviation of relative electron transport rates (rETRs) from oxygen-based photosynthesis rates. Thus, the photosynthetic parameters α-slope and P(max) derived from rETRs strongly depend on the specific cellular absorptivity and cannot be used to compare the photosynthetic performance of cells with different optical properties. However, it was shown that E(k) is independent of cellular absorptivity and could be used to compare samples with unknown optical properties. PMID:21571541

  16. Effects of Shading Stress and Light Recovery on the Photosynthesis Characteristic and Chlorophyll Fluorescence Characteristic of Fragaria Ananassa Duch. cv. Toyonoka

    Directory of Open Access Journals (Sweden)

    Renyan Duan

    2013-06-01

    Full Text Available Light is an important resource for plant growth and development, crops need to change their physiological characteristics to different light environments. Fragaria ananassa Duch. cv. Toyonoka. is an important economic plant which is widely planted at home. A greenhouse experiment was conducted from April 2010 with different sun-shading treatment, 85% (CK, 60% (T1, 35% (T2 and 10% (T3. After 7 days of shading stress, the physiological characteristics were slowly recovered. The results showed that (1 Under shading condition, Light saturation rate (Amax, Apparent Quantum Yield (AQY, Carboxylation Efficiency (CE, dark respiration (Rd, Light Saturation Point (LSP and Light Compensation Point (LCP became lower. (2 The maximal fluorescence (Fm, light energy transformation efficiency of PS II (Fv/Fm, actual photochemical efficiency of PS II in the light (Yield, photochemical quenching coefficient (qP declined with shading stress increase. (3 There were significant difference in the chlorophyll fluorescence parameters among different treatment groups by the end of sun-shading treatment (p<0.05. After the light was recovered, the physiological characteristics could rapidly recover under low shading stress and moderate shading stress, while in severe shading stress the physiological characteristics hardly recover.

  17. Response of carbon assimilation and chlorophyll fluorescence to soybean leaf phosphorus across CO2: Alternative electron sink, nutrient efficiency and critical concentration.

    Science.gov (United States)

    Singh, Shardendu K; Reddy, Vangimalla R

    2015-10-01

    To evaluate the response of CO2 assimilation rate (PN) and various chlorophyll fluorescence (CF) parameters to phosphorus (P) nutrition, soybean plants were grown in controlled environment with sufficient (0.50mM) and deficient (0.10 and 0.01 mM) phosphate (P) supply under ambient and elevated CO2 (aCO2, 400 and eCO2, 800 μmol mol(-1), respectively). Measurements were made at ambient (21%) and low (2%) O2 concentrations. Results showed strong correlation of leaf P concentration with PN and CF parameters. The P deficiency showed parallel decreases in PN, and CF parameters including quantum efficiency (Fv'/Fm'), quantum yield of photosystem II (ΦPSII), electron transport rate (JF), and photochemical quenching (qP). The Fv'/Fm' decreased as a result of greater decline in maximal (Fm') than minimal (Fo') fluorescence. The eCO2 stimulated PN especially under higher leaf P concentrations. Low O2 also stimulated PN but only at aCO2. The photosynthetic carbon reduction (PCR, signified by PN) and photorespiratory carbon oxidation cycles (PCO, signified photorespiration as indicated by ratio of JF to gross PN and % increase in PN at 2% O2) was the major electron sinks. However, the presence of alternative electron sink was also evident as determined by the difference between the electron transport calculated from chlorophyll fluorescence and gas exchange measurements. Alternative electron sink declined at lower leaf P concentration suggesting its minor role in photochemical energy consumption, thus dissipation of the excess excitation pressure of PSII reaction center under P deficiency. The JF/PG and % increase in PN at 2 versus 21% O2 remained consistent across leaf P concentration suggesting PCO cycle as an important mechanism to dissipate excess excitation energy in P deficient leaves. The severe decline of Fv'/Fm', ΦPSII, JF and qP under P deficiency also suggested the occurrences of excess radiant energy dissipation by non-photochemical quenching mechanisms. Critical

  18. Screening for Barley Waterlogging Tolerance in Nordic Barley Cultivars (Hordeum vulgare L.) Using Chlorophyll Fluorescence on Hydroponically-Grown Plants

    OpenAIRE

    Nils-Ove Bertholdsson

    2013-01-01

    Waterlogging can reduce crop yield by 20%–50% or more, and lack of efficient selection methods is an obstacle in plant breeding. The methods currently used are mainly indices based on germination ability in Petri dishes and leaf chlorosis in plants grown in waterlogged soils. Cultivation in oxygen-depleted nutrient solution is the ultimate waterlogging system. Therefore methods based on root growth inhibition and on fluorescence in plant material hydroponically grown in oxygen-depleted soluti...

  19. Sun-induced Chlorophyll fluorescence and PRI improve remote sensing GPP estimates under varying nutrient availability in a typical Mediterranean savanna ecosystem

    Directory of Open Access Journals (Sweden)

    O. Perez-Priego

    2015-07-01

    Full Text Available This study investigates the performances of different optical indices to estimate gross primary production (GPP of herbaceous stratum in a Mediterranean savanna with different Nitrogen (N and Phosphorous (P availability. Sun-induced chlorophyll Fluorescence yield computed at 760 nm (Fy760, scaled-photochemical reflectance index (sPRI, MERIS terrestrial-chlorophyll index (MTCI and Normalized difference vegetation index (NDVI were computed from near-surface field spectroscopy measurements collected using high spectral resolution spectrometers covering the visible near-infrared regions. GPP was measured using canopy-chambers on the same locations sampled by the spectrometers. We hypothesized that light-use efficiency (LUE models driven by remote sensing quantities (RSM can better track changes in GPP caused by nutrient supplies compared to those driven exclusively by meteorological data (MM. Particularly, we compared the performances of different RSM formulations – relying on the use of Fy760 or sPRI as proxy for LUE and NDVI or MTCI as fraction of absorbed photosynthetically active radiation (fAPAR – with those of classical MM. Results showed significantly higher GPP in the N fertilized experimental plots during the growing period. These differences in GPP disappeared in the drying period when senescence effects masked out potential differences due to plant N content. Consequently, although MTCI was tightly related to plant N content (r2 = 0.86, p r2 = 0.45, p cv = 127, MEcv = 0.879 outperformed RSM (AICcv = 140, MEcv = 0.8737 when soil moisture was used to constrain the seasonal dynamic of LUE. However, residual analyses demonstrated that MM is predictively inaccurate whenever no climatic variable explicitly reveals nutrient-related changes in the LUE parameter. These results put forward that RSM is a valuable means to diagnose nutrient-induced effects on the photosynthetic activity.

  20. Gas exchange and chlorophyll fluorescence of pea (Pisum sativum L.) plants in response to ambient ozone at a rural site in Egypt.

    Science.gov (United States)

    Ismail, I M; Basahi, J M; Hassan, I A

    2014-11-01

    Egyptian pea cultivars (Pisum sativum L. cultivars Little Marvel, Perfection and Victory) grown in open-top chambers were exposed to either charcoal-filtered (FA) or non-filtered air (NF) for five consecutive years (2009-2013) at a rural site in northern Egypt. Net photosynthetic rates (PN), stomatal conductance (gs), intercellular CO2 (Ci) and chlorophyll fluorescence were measured. Ozone (O3) was found to be the most prevalent pollutant common at the rural site and is suspected to be involved in the alteration of the physiological parameters measured in the present investigation. PN of different cultivars were found to respond similarly; decreases of 23, 29 and 39% were observed in the cultivars Perfection, Little Marvel and Victory, respectively (averaged over the five years) due to ambient O3. The maximum impairment in PN was recorded in the cultivar Victory (46%) in 2013 when the highest O3 levels were recorded (90 nL L(-1)). The average stomatal conductance decreased by 20 and 18% in the cultivars Little Marvel and Perfection, respectively, while the average stomatal conductance increased on average by 27% in the cultivar Victory. A significant correlation was found between PN and Ci, indicating the importance of non-stomatal limitations of photosynthesis, especially in the cultivar Victory. The PN vs. Ci curves were fitted to a non-rectangular hyperbolic model. The actual quantum yield (ΦPSII) and photochemical quenching coefficient (qP) were significantly decreased in the leaves of plants exposed to NF air. Non-photochemical quenching (NPQ) was increased in all cultivars. Exposure to NF air caused reductions in chlorophyll (Chl a) of 19, 16 and 30% in the Little Marvel, Perfection and Victory cultivars, respectively.

  1. Chlorophyll fluorescence kinetics, photosynthetic activity, and pigment composition of blue-shade and half-shade leaves as compared to sun and shade leaves of different trees.

    Science.gov (United States)

    Lichtenthaler, Hartmut K; Babani, Fatbardha; Navrátil, Martin; Buschmann, Claus

    2013-11-01

    The chlorophyll (Chl) fluorescence induction kinetics, net photosynthetic CO2 fixation rates P N, and composition of photosynthetic pigments of differently light exposed leaves of several trees were comparatively measured to determine the differences in photosynthetic activity and pigment adaptation of leaves. The functional measurements were carried out with sun, half-shade and shade leaves of seven different trees species. These were: Acer platanoides L., Ginkgo biloba L., Fagus sylvatica L., Platanus x acerifolia Willd., Populus nigra L., Quercus robur L., Tilia cordata Mill. In three cases (beech, ginkgo, and oak), we compared the Chl fluorescence kinetics and photosynthetic rates of blue-shade leaves of the north tree crown receiving only blue sky light but no direct sunlight with that of sun leaves. In these cases, we also determined in detail the pigment composition of all four leaf types. In addition, we determined the quantum irradiance and spectral irradiance of direct sunlight, blue skylight as well as the irradiance in half shade and full shade. The results indicate that sun leaves possess significantly higher mean values for the net CO2 fixation rates P N (7.8-10.7 μmol CO2 m(-2) s(-1) leaf area) and the Chl fluorescence ratio R Fd (3.85-4.46) as compared to shade leaves (mean P N of 2.6-3.8 μmol CO2 m(-2) s(-1) leaf area.; mean R Fd of 1.94-2.56). Sun leaves also exhibit higher mean values for the pigment ratio Chl a/b (3.14-3.31) and considerably lower values for the weight ratio total chlorophylls to total carotenoids, (a + b)/(x + c), (4.07-4.25) as compared to shade leaves (Chl a/b 2.62-2.72) and (a + b)/(x + c) of 5.18-5.54. Blue-shade and half-shade leaves have an intermediate position between sun and shade leaves in all investigated parameters including the ratio F v/F o (maximum quantum yield of PS2 photochemistry) and are significantly different from sun and shade leaves but could not be differentiated from each other. The

  2. Remote monitoring of chlorophyll fluorescence in two reef corals during the 2005 bleaching event at Lee Stocking Island, Bahamas

    Science.gov (United States)

    Manzello, D.; Warner, M.; Stabenau, E.; Hendee, J.; Lesser, M.; Jankulak, M.

    2009-03-01

    Zooxanthellae fluorescence was measured in situ, remotely, and in near real-time with a pulse amplitude modulated (PAM) fluorometer for a colony of Siderastrea siderea and Agaricia tenuifolia at Lee Stocking Island, Bahamas during the Caribbean-wide 2005 bleaching event. These colonies displayed evidence of photosystem II (PS II) inactivation coincident with thermal stress and seasonally high doses of solar radiation. Hurricane-associated declines in temperature and light appear to have facilitated the recovery of maximum quantum yield of PS II within these two colonies, although both corals responded differently to individual storms. PAM fluorometry, coupled with long-term measurement of in situ light and temperature, provides much more detail of coral photobiology on a seasonal time scale and during possible bleaching conditions than sporadic, subjective, and qualitative observations. S. siderea displayed evidence of PS II inactivation over a month prior to the issuing of a satellite-based, sea surface temperature (SST) bleaching alert by the National Oceanic and Atmospheric Administration (NOAA). In fact, recovery had already begun in S. siderea when the bleaching alert was issued. Fluorescence data for A. tenuifolia were difficult to interpret because the shaded parts of a colony were monitored and thus did not perfectly coincide with thermal stress and seasonally high doses of solar radiation as in S. siderea. These results further emphasize the limitations of solely monitoring SST (satellite or in situ) as a bleaching indicator without considering the physiological status of coral-zooxanthellae symbioses.

  3. Responses of chlorophyll fluorescence and nitrogen level of Leymus chinensis Seedling to changes of soil moisture and temperature

    Institute of Scientific and Technical Information of China (English)

    XU Zhen-zhu; ZHOU Guang-sheng; LI Hui

    2004-01-01

    Controlled experiment of Leymus chinensis seedlings grown in the environmental growth chambers at 3 soilmoisture levels and 3 temperature levels was conducted in order to improve the understanding how leafphotosynthetic parameters will respond to climatic change. The results indicated that soil drought and hightemperature decreased the photochemical efficiency of photosystem (Fv/Fm ), the overall photochemical quantumyield of PSIl(yield), the coefficient of photochemical fluorescence quenching(qp), but increased the coefficient ofnon-photochemical fluorescence quenching(qN). Severe soil drought would decrease Fv/Fm and yield by 3.12% and 37.04% under 26℃ condition, respectively, and 6.60% and 73.33% under 32℃ condition, respectively, suggesting that higher temperature may enhance the negative effects of soil drought. All the soil drought treatments resulted in the decline in leaf nitrogen content. There was no significant effect of temperature on leaf nitrogen level, but higher temperature significantly reduced the root nitrogen content and the ratio of root nitrogen to leaf nitrogen, indicating the different strategies of adaptation to soil drought and temperature. It was also implied that higher temperature would enhance the effect of soil drought on leaf photosynthetic capacity, decrease the adaptability of Leymus chinensis to drought.

  4. Photoelectric effects on chlorophyll fluorescence of photosystem II in vivo. Kinetics in the absence and presence of valinomycin.

    Science.gov (United States)

    Vredenberg, Wim J; Bulychev, Alexander

    2003-08-01

    Fluorescence induction curves (F(t)) in low intensity 1s light pulses have been measured in leaf discs in the presence and absence of valinomycin (VMC). Addition of VMC causes: (i) no effect on the initial fluorescence level Fo and the initial (O-J) phase of F(t) in the 0.01-1 ms time range. (ii) An approximately 10% decrease in the maximal fluorescence Fm in the light reached at the P level in the O-J-I-P induction curve. (iii) Nearly twofold increase in the rate and extent of the F(t) rise in the J-I phase in the 1-50 ms time range. (iv) A 60-70% decrease in the rise (I-P phase) in the 50-1000 ms time range with no appreciable effect, if at all, on the rate. System analysis of F(t) in terms of rate constants of electron transfer at donor and acceptor sides have been done using the Three State Trapping Model (TSTM). This reveals that VMC causes: (i) no, or very little effect on rate constants of e-transfer reactions powered by PSII. (ii) A manifold lower rate constant of radical pair recombination (k(-1)) in the light as compared to that in the control. The low rate constant of radical pair recombination in the reaction center (RC) in the presence of VMC is reflected by a substantial increase in the nonzero trapping efficiency in RCs in which the primary quinone acceptor (Q(A)) is reduced (semi-open centers). This causes an increase in their rate of closure and in the overall trapping efficiency. Data suggest evidence that membrane chaotropic agents like VMC abolish the stimulation of the rate constant of radical pair recombination by light. This light stimulation that becomes apparent as an increase in Fo has been documented before [Biophys. J. 79 (2000) 26]. It has been ascribed to effects of (changes in) local electric fields in the vicinity of the RC. The decrease of the I-P phase is attributed to a decrease in the photoelectric trans-thylakoid potential in the presence of VMC. Such effects have been hypothesized and illustrated.

  5. Estresse salino em duas variedades de cana-de-açúcar: enzimas do sistema antioxidativo e fluorescência da clorofila Salinity stress in two varieties of sugar cane: enzymes of the antioxidant system and chlorophyll fluorescence

    Directory of Open Access Journals (Sweden)

    Lilia Willadino

    2011-06-01

    Full Text Available O Brasil destaca-se por ser o maior produtor de cana-de-açúcar (Saccharum officinarum L. e por dominar todos os estágios da tecnologia de produção de açúcar e etanol. Atualmente se observa a expansão dessa cultura para a região semiárida brasileira, a qual apresenta solos propensos à salinização. O presente trabalho objetivou avaliar a resposta à salinidade de duas variedades de cana-de-açúcar. O ensaio foi implantado em casa de vegetação, em delineamento inteiramente casualizado, em esquema fatorial 2 x 8 com cinco repetições, correspondendo a duas variedades de cana-de-açúcar (RB867515 e RB863129 e oito níveis de NaCl (0; 25; 50; 75; 100; 125; 150; 200 mM de NaCl. A salinidade induziu aumento na fluorescência e diminuição na concentração de clorofila em ambas as variedades. A redução da clorofila, entretanto, foi maior na variedade RB867515. Observou-se, nesta mesma variedade, aumento da atividade da peroxidase do ascorbato (APX e da catalase (CAT, enquanto na variedade RB863129 ocorreu redução na atividade dessas enzimas. Esses resultados indicam que a variedade RB867515 apresenta um mecanismo mais eficiente na proteção da planta contra danos no aparato fotoquímico e contra a ação de espécies reativas de oxigênio, em particular o H2O2.Brazil is seen as being the largest producer of sugarcane (Saccharum officinarum L. and of mastering all stages in the production of sugar and ethanol. Currently this production is being expanded into the semi-arid regions of Brazil, where there are soil-types prone to salinity. This study aimed to evaluate the response to salinity in two sugarcane genotypes, RB867515 and RB863129. Salinity caused an increase in chlorophyll fluorescence and a reduction of chlorophyll concentration in both varieties. The reduction of chlorophyll however was higher in RB867515. In this same type, an increase in the activity of ascorbate peroxidase (APX and catalase (CAT was observed, while in

  6. New methods for the retrieval of chlorophyll red fluorescence from hyperspectral satellite instruments: simulations and application to GOME-2 and SCIAMACHY

    Science.gov (United States)

    Joiner, Joanna; Yoshida, Yasuko; Guanter, Luis; Middleton, Elizabeth M.

    2016-08-01

    Global satellite measurements of solar-induced fluorescence (SIF) from chlorophyll over land and ocean have proven useful for a number of different applications related to physiology, phenology, and productivity of plants and phytoplankton. Terrestrial chlorophyll fluorescence is emitted throughout the red and far-red spectrum, producing two broad peaks near 683 and 736 nm. From ocean surfaces, phytoplankton fluorescence emissions are entirely from the red region (683 nm peak). Studies using satellite-derived SIF over land have focused almost exclusively on measurements in the far red (wavelengths > 712 nm), since those are the most easily obtained with existing instrumentation. Here, we examine new ways to use existing hyperspectral satellite data sets to retrieve red SIF (wavelengths < 712 nm) over both land and ocean. Red SIF is thought to provide complementary information to that from the far red for terrestrial vegetation. The satellite instruments that we use were designed to make atmospheric trace-gas measurements and are therefore not optimal for observing SIF; they have coarse spatial resolution and only moderate spectral resolution (0.5 nm). Nevertheless, these instruments, the Global Ozone Monitoring Instrument 2 (GOME-2) and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY), offer a unique opportunity to compare red and far-red terrestrial SIF at regional spatial scales. Terrestrial SIF has been estimated with ground-, aircraft-, or satellite-based instruments by measuring the filling-in of atmospheric and/or solar absorption spectral features by SIF. Our approach makes use of the oxygen (O2) γ band that is not affected by SIF. The SIF-free O2 γ band helps to estimate absorption within the spectrally variable O2 B band, which is filled in by red SIF. SIF also fills in the spectrally stable solar Fraunhofer lines (SFLs) at wavelengths both inside and just outside the O2 B band, which further helps to estimate red SIF

  7. Effects of nitrogen form on growth,CO2 assimilation,chlorophyll fluorescence,and photosynthetic electron allocation in cucumber and rice plants

    Institute of Scientific and Technical Information of China (English)

    Yan-hong ZHOU; Yi-li ZHANG; Xue-min WANG; Jin-xia CUI; Xiao-jian XIA; Kai SHI; Jing-quan YU

    2011-01-01

    Cucumber and rice plants with varying ammonium(NH4+)sensitivities were used to examine the effects of different nitrogen(N)sources on gas exchange,chlorophyll(ChI)fluorescence quenching,and photosynthetic electron allocation.Compared to nitrate(NO3-)-grown plants,cucumber plants grown under NH4+-nutdtion showed decreased plant growth,net photosynthetic rate,stomatal conductance,intercellular carbon dioxide(CO2)level,transpiration rate,maximum photochemical efficiency of photosystem Ⅱ,and O2-independent alternative electron flux,and increased O2-dependent alternative electron flux.However,the N source had little effect on gas exchange,ChI a fluorescence parameters,and photosynthetic electron allocation in rice plants,except that NH4+-grown plants had a higher O2-independent alternative electron flux than NO3--grown plants.NO3-reduction activity was rarely detected in leaves of NH4+-grown cucumber plants,but was high in NH4+-grown rice plants.These results demonstrate that significant amounts of photosynthetic electron transport were coupled to NO3-assimilation,an effect more significant in NO3--grown plants than in NH4+-grown plants.Meanwhile,NH4+-tolerant plants exhibited a higher demand for the reduced form of nicotinamide adenine dinucleotide phosphate(NADPH)for NO3-reduction,regardless of the N form supplied,while NH4+-sensitive plants had a high water-water cycle activity when NH4+was supplied as the sole N source.

  8. Chlorophyll a fluorescence responses of temperate Phaeophyceae under submersion and emersion regimes: a comparison of rapid and steady-state light curves.

    Science.gov (United States)

    Nitschke, Udo; Connan, Solène; Stengel, Dagmar B

    2012-10-01

    The potential of algae to acclimate to environmental stress is commonly assessed using chlorophyll a fluorescence, with changes in parameters of photosynthesis versus irradiance (P/E) curves measured either as rapid light curves (RLC) or steady-state light curves (LC). Here, effects of emersion on primary photosynthesis of four brown macroalgae (Ascophyllum nodosum, Fucus serratus, Sargassum muticum, Laminaria digitata) were compared by applying both RLC and LC. When LC were used, photosynthetic performance was enhanced during emersion in A. nodosum and F. serratus as shown by increases in q(P), rETR(max) and E(k). By contrast, emersion had no impact on photosynthetic parameters of S. muticum and L. digitata. Relative changes in the NPQ-rETR relationship were reduced in A. nodosum, F. serratus and S. muticum, but remained unaffected in L. digitata. As none of the species developed their potential NPQ(max), corresponding values could not be determined from RLC. Using RLC, observed photosynthetic performance of F. serratus and L. digitata was reduced upon emersion, whilst values for NPQ(max) were enhanced. Only results derived from LC provide evidence for a potential physiological adaptation of brown macroalgae to their natural habitat; it is recommended using the LC protocol to detect environmental impacts on photosynthesis. PMID:22915336

  9. Photochemical properties in flag leaves of a super-high-yielding hybrid rice and a traditional hybrid rice (Oryza sativa L.) probed by chlorophyll a fluorescence transient.

    Science.gov (United States)

    Zhang, Meiping; Shan, YongJie; Kochian, Leon; Strasser, Reto J; Chen, GuoXiang

    2015-12-01

    Chlorophyll a fluorescence of flag leaves in a super-high-yielding hybrid rice (Oryza sativa L.) LYPJ, and a traditional hybrid rice SY63 cultivar with lower grain yield, which were grown in the field, were investigated from emergence through senescence of flag leaves. As the flag leaf matured, there was an increasing trend in photosynthetic parameters such as quantum efficiency of primary photochemistry ([Formula: see text] Po) and efficiency of electron transport from PS II to PS I (Ψ Eo). The overall photosynthetic performance index (PIABS) was significantly higher in the high-yielding LYPJ compared to SY63 during the entire reproductive stage of the plant, the same to MDA content. However, [Formula: see text] Po(=F V/F M), an indicator of the primary photochemistry of the flag leaf, did not display significant changes with leaf age and was not significantly different between the two cultivars, suggesting that PIABS is a more sensitive parameter than [Formula: see text] Po (=F V/F M) during leaf age for distinguishing between cultivars differing in yield.

  10. Mapping intercellular CO2 mole fraction (Ci) in rosa rubiginosa leaves fed with abscisic acid by using chlorophyll fluorescence imaging. Significance Of ci estimated from leaf gas exchange

    Science.gov (United States)

    Meyer; Genty

    1998-03-01

    Imaging of photochemical yield of photosystem II (PSII) computed from leaf chlorophyll fluorescence images and gas-exchange measurements were performed on Rosa rubiginosa leaflets during abscisic acid (ABA) addition. In air ABA induced a decrease of both the net CO2 assimilation (An) and the stomatal water vapor conductance (gs). After ABA treatment, imaging in transient nonphotorespiratory conditions (0.1% O2) revealed a heterogeneous decrease of PSII photochemical yield. This decline was fully reversed by a transient high CO2 concentration (7400 mol mol-1) in the leaf atmosphere. It was concluded that ABA primarily affected An by decreasing the CO2 supply at ribulose-1,5-bisphosphate carboxylase/oxygenase. Therefore, the An versus intercellular mole fraction (Ci) relationship was assumed not to be affected by ABA, and images of Ci and gs were constructed from images of PSII photochemical yield under nonphotorespiratory conditions. The distribution of gs remained unimodal following ABA treatment. A comparison of calculations of Ci from images and gas exchange in ABA-treated leaves showed that the overestimation of Ci estimated from gas exchange was only partly due to heterogeneity. This overestimation was also attributed to the cuticular transpiration, which largely affects the calculation of the leaf conductance to CO2, when leaf conductance to water is low. PMID:9501127

  11. Monitoring and Assessing the 2012 Drought in the Great Plains: Analyzing Satellite-Retrieved Solar-Induced Chlorophyll Fluorescence, Drought Indices, and Gross Primary Production

    Directory of Open Access Journals (Sweden)

    Siheng Wang

    2016-01-01

    Full Text Available We examined the relationship between satellite measurements of solar-induced chlorophyll fluorescence (SIF and several meteorological drought indices, including the multi-time-scale standard precipitation index (SPI and the Palmer drought severity index (PDSI, to evaluate the potential of using SIF to monitor and assess drought. We found significant positive relationships between SIF and drought indices during the growing season (from June to September. SIF was found to be more sensitive to short-term SPIs (one or two months and less sensitive to long-term SPI (three months than were the normalized difference vegetation index (NDVI or the normalized difference water index (NDWI. Significant correlations were found between SIF and PDSI during the growing season for the Great Plains. We found good consistency between SIF and flux-estimated gross primary production (GPP for the years studied, and synchronous declines of SIF and GPP in an extreme drought year (2012. We used SIF to monitor and assess the drought that occurred in the Great Plains during the summer of 2012, and found that although a meteorological drought was experienced throughout the Great Plains from June to September, the western area experienced more agricultural drought than the eastern area. Meanwhile, SIF declined more significantly than NDVI during the peak growing season. Yet for senescence, during which time the reduction of NDVI still went on, the reduction of SIF was eased. Our work provides an alternative to traditional reflectance-based vegetation or drought indices for monitoring and assessing agricultural drought.

  12. Sun-induced chlorophyll fluorescence from high-resolution imaging spectroscopy data to quantify spatio-temporal patterns of photosynthetic function in crop canopies.

    Science.gov (United States)

    Pinto, Francisco; Damm, Alexander; Schickling, Anke; Panigada, Cinzia; Cogliati, Sergio; Müller-Linow, Mark; Balvora, Agim; Rascher, Uwe

    2016-07-01

    Passive detection of sun-induced chlorophyll fluorescence (SIF) using spectroscopy has been proposed as a proxy to quantify changes in photochemical efficiency at canopy level under natural light conditions. In this study, we explored the use of imaging spectroscopy to quantify spatio-temporal dynamics of SIF within crop canopies and its sensitivity to track patterns of photosynthetic activity originating from the interaction between vegetation structure and incoming radiation as well as variations in plant function. SIF was retrieved using the Fraunhofer Line Depth (FLD) principle from imaging spectroscopy data acquired at different time scales a few metres above several crop canopies growing under natural illumination. We report the first maps of canopy SIF in high spatial resolution. Changes of SIF were monitored at different time scales ranging from quick variations under induced stress conditions to seasonal dynamics. Natural changes were primarily determined by varying levels and distribution of photosynthetic active radiation (PAR). However, this relationship changed throughout the day demonstrating an additional physiological component modulating spatio-temporal patterns of SIF emission. We successfully used detailed SIF maps to track changes in the canopy's photochemical activity under field conditions, providing a new tool to evaluate complex patterns of photosynthesis within the canopy. PMID:26763162

  13. 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.

  14. 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.

  15. 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. PMID:25923517

  16. 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. PMID:26286697

  17. A framework to quantify the determinants of canopy photosynthesis and carbon uptake using time series of chlorophyll fluorescence

    Science.gov (United States)

    Kellner, J. R.; Cushman, K. C.; Kendrick, J. A.; Silva, C. E.; Wiseman, S. M.; Yang, X.

    2015-12-01

    Uncertainty over the sign and magnitude of environmental forcing agents on fluxes of tropical forest carbon could be reduced with measurements of canopy photosynthesis. But no existing method can quantify photosynthesis within individual plants at scales larger than a few cm. Portable leaf chambers can determine leaf-level gas exchange, and eddy-covariance instruments infer the net ecosystem-atmosphere carbon flux. These endpoints represent an axis of granularity and extent. Single leaf measurements are finely grained, but necessarily limited in extent, and gas exchange for whole landscapes cannot resolve the performance or contributions of individual plants. This limits the ability of scientists to test mechanistic demographic and physiological hypotheses about the drivers of photosynthesis in ecosystems, and therefore to understand the determinants of carbon fluxes between tropical ecosystems and the atmosphere. Here I describe a framework to overcome these challenges using a program of drone-enabled remote sensing measurements of solar-induced fluorescence (SIF) coupled with ground-based physiological studies to understand the determinants of photosynthesis within leaves, individual organisms and large landscapes. The Brown Platform for Autonomous Remote Sensing (BPAR) is a suite of sensors carried by a gas-powered helicopter drone. By conducting frequent, low-altitude flights BPAR can produce VNIR imaging spectroscopy time series with measurements separated by minutes to hours at ground sample distances of 1 cm. The talk will focus on how measurements of SIF at these spatial and temporal scales can be coupled with models to infer the rate of electron transport and carbon assimilation.

  18. Sun-induced chlorophyll fluorescence and photochemical reflectance index improve remote-sensing gross primary production estimates under varying nutrient availability in a typical Mediterranean savanna ecosystem

    Science.gov (United States)

    Perez-Priego, O.; Guan, J.; Rossini, M.; Fava, F.; Wutzler, T.; Moreno, G.; Carvalhais, N.; Carrara, A.; Kolle, O.; Julitta, T.; Schrumpf, M.; Reichstein, M.; Migliavacca, M.

    2015-11-01

    This study investigates the performances of different optical indices to estimate gross primary production (GPP) of herbaceous stratum in a Mediterranean savanna with different nitrogen (N) and phosphorous (P) availability. Sun-induced chlorophyll fluorescence yield computed at 760 nm (Fy760), scaled photochemical reflectance index (sPRI), MERIS terrestrial-chlorophyll index (MTCI) and normalized difference vegetation index (NDVI) were computed from near-surface field spectroscopy measurements collected using high spectral resolution spectrometers covering the visible near-infrared regions. GPP was measured using canopy chambers on the same locations sampled by the spectrometers. We tested whether light-use efficiency (LUE) models driven by remote-sensing quantities (RSMs) can better track changes in GPP caused by nutrient supplies compared to those driven exclusively by meteorological data (MM). Particularly, we compared the performances of different RSM formulations - relying on the use of Fy760 or sPRI as a proxy for LUE and NDVI or MTCI as a fraction of absorbed photosynthetically active radiation (fAPAR) - with those of classical MM. Results showed higher GPP in the N-fertilized experimental plots during the growing period. These differences in GPP disappeared in the drying period when senescence effects masked out potential differences due to plant N content. Consequently, although MTCI was closely related to the mean of plant N content across treatments (r2 = 0.86, p < 0.01), it was poorly related to GPP (r2 = 0.45, p < 0.05). On the contrary sPRI and Fy760 correlated well with GPP during the whole measurement period. Results revealed that the relationship between GPP and Fy760 is not unique across treatments, but it is affected by N availability. Results from a cross-validation analysis showed that MM (AICcv = 127, MEcv = 0.879) outperformed RSM (AICcv =140, MEcv = 0.8737) when soil moisture was used to constrain the seasonal dynamic of LUE. However

  19. Sun-induced Chlorophyll fluorescence and PRI improve remote sensing GPP estimates under varying nutrient availability in a typical Mediterranean savanna ecosystem

    Science.gov (United States)

    Perez-Priego, O.; Guan, J.; Rossini, M.; Fava, F.; Wutzler, T.; Moreno, G.; Carvalhais, N.; Carrara, A.; Kolle, O.; Julitta, T.; Schrumpf, M.; Reichstein, M.; Migliavacca, M.

    2015-07-01

    This study investigates the performances of different optical indices to estimate gross primary production (GPP) of herbaceous stratum in a Mediterranean savanna with different Nitrogen (N) and Phosphorous (P) availability. Sun-induced chlorophyll Fluorescence yield computed at 760 nm (Fy760), scaled-photochemical reflectance index (sPRI), MERIS terrestrial-chlorophyll index (MTCI) and Normalized difference vegetation index (NDVI) were computed from near-surface field spectroscopy measurements collected using high spectral resolution spectrometers covering the visible near-infrared regions. GPP was measured using canopy-chambers on the same locations sampled by the spectrometers. We hypothesized that light-use efficiency (LUE) models driven by remote sensing quantities (RSM) can better track changes in GPP caused by nutrient supplies compared to those driven exclusively by meteorological data (MM). Particularly, we compared the performances of different RSM formulations - relying on the use of Fy760 or sPRI as proxy for LUE and NDVI or MTCI as fraction of absorbed photosynthetically active radiation (fAPAR) - with those of classical MM. Results showed significantly higher GPP in the N fertilized experimental plots during the growing period. These differences in GPP disappeared in the drying period when senescence effects masked out potential differences due to plant N content. Consequently, although MTCI was tightly related to plant N content (r2 = 0.86, p < 0.01), it was poorly related to GPP (r2 = 0.45, p < 0.05). On the contrary sPRI and Fy760 correlated well with GPP during the whole measurement period. Results revealed that the relationship between GPP and Fy760 is not unique across treatments but it is affected by N availability. Results from a cross validation analysis showed that MM (AICcv = 127, MEcv = 0.879) outperformed RSM (AICcv = 140, MEcv = 0.8737) when soil moisture was used to constrain the seasonal dynamic of LUE. However, residual analyses

  20. Trocas gasosas e fluorescência da clorofila em seis cultivares de cafeeiro sob estresse de alumínio Gas exchange and chlorophyll fluorescence in six coffee cultivars under aluminum stress

    Directory of Open Access Journals (Sweden)

    Maria Luiza Freitas Konrad

    2005-01-01

    Full Text Available Em experimento desenvolvido em casa de vegetação e em câmara de crescimento avaliou-se o efeito do alumínio (Al na fotossíntese de seis cultivares de cafeeiro. As plantas foram cultivadas em solução nutritiva aerada continuamente, contendo duas concentrações de Al, 0 e 0,148 mmol L-1, fornecidas como Al2(SO43. Após 97 dias mediram-se as taxas de assimilação de CO2 (A e transpiração (E, a condutância estomática (gs, a concentração interna de CO2 (Ci, eficiência instantânea de carboxilação (fic e variáveis de fluorescência da clorofila. Em todas as cultivares, a presença de Al causou quedas significantes em A, gs, fic, ocorrendo aumento em Ci. Também se observou aumento significativo na fluorescência basal (Fo e queda na eficiência quântica máxima do fotossistema II (Fv/Fm, sugerindo injúrias na estrutura dos tilacóides causadas pelo Al. Na curva de indução de fotossíntese, observou-se que o Al causou queda no coeficiente de extinção fotoquímica da fluorescência e aumento no coeficiente de extinção não fotoquímico. Os resultados desse estudo indicaram que a queda de A foi devida à queda da condutância estomática, nas atividades bioquímicas e fotoquímicas.Experiments were carried out under greenhouse and growth chamber to evaluate the effects of aluminum (Al on several photosynthetic characteristics in six coffee cultivars. Plants were grown in nutrient solution aerated continuously, containing two Al concentration, 0 and 0.148 mmol L-1, supplied as Al2(SO43. After 97 days of treatament, measurements of CO2 assimilation rate (A, transpiration rate (E, stomatal conductance (gs, internal CO2 concentration (Ci, instantaneous carboxylation efficiency (phic and chlorophyll fluorescence related characteristics were performed. All six cultivars showed decrease in A, gs and phic and increase in Ci. The basal chlorophyll fluorescence yield (Fo increased and the maximum quantum efficiency (Fv/Fm decreased

  1. Photosynthetic acclimation to photon irradiance and its relation to chlorophyll fluorescence and carbon assimilation in the halotolerant green alga Dunaliella viridis.

    Science.gov (United States)

    Gordillo, F J; Jiménez, C; Chavarría, J; Xavier Niell, F

    2001-01-01

    This work describes the long-term acclimation of the halotolerant microalga Dunaliella viridis to different photon irradiance, ranging from darkness to 1500 mumol m(-2) s(-1). In order to assess the effects of long-term photoinhibition, changes in oxygen production rate, pigment composition, xanthophyll cycle and in vivo chlorophyll fluorescence using the saturating pulse method were measured. Growth rate was maximal at intermediate irradiance (250 and 700 mumol m(-2) s(-1)). The increase in growth irradiance from 700 to 1500 mumol m(-2) s(-1) did not lead to further significant changes in pigment composition or EPS, indicating saturation in the pigment response to high light. Changes in Photosystem II optimum quantum yield (F(v)/F(m)) evidenced photoinhibition at 700 and especially at 1500 mumol m(-2) s(-1). The relation between photosynthetic electron flow rate and photosyntetic O(2) evolution was linear for cultures in darkness shifting to curvilinear as growth irradiance increased, suggesting the interference of the energy dissipation processes in oxygen evolution. Carbon assimilation efficiencies were studied in relation to changes in growth rate, internal carbon and nitrogen composition, and organic carbon released to the external medium. All illuminated cultures showed a high capability to maintain a C:N ratio between 6 and 7. The percentage of organic carbon released to the external medium increased to its maximum under high irradiance (1500 mumol m(-2) s(-1)). These results suggest that the release of organic carbon could act as a secondary dissipation process when the xanthophyll cycle is saturated. PMID:16228345

  2. Chlorophyll Fluorescence Characteristics of Physiologically Etiolated Cinnamomum camphora leaves%生理性黄化香樟叶绿素荧光特性的研究

    Institute of Scientific and Technical Information of China (English)

    袁梦; 陈晓娟; 秦金舟; 刘桂华

    2013-01-01

    The daily changes of chlorophyll fluorescence parameters of Cinnamomum camphora leaves at different levels of etiolation were studied .The results showed that the F0(minimal fluorescence ),Fm(maximal flu-orescence),Fm′(actual maximal fluorescence ),Fv(variable fluorescence ),Fv/Fm(optimal/maximal photochemi-cal efficiency of PSⅡ),Fm/F0(electron transfer rate ),and Fv/F0(potential activity of PSⅡ) first increased and then descended in the healthy and light-etiolated camphor leaves between 08:00-16:00,and the highest values occurred between 12:00 to 14:00.The daily change trend of N P,Q(non-photochemical quenching ) was contrary to those parameters mentioned above ,the trend was first increasing and then descending ,and the lowest values of Fm/F0 and Fv/F0 occurred in the period of 12:00 to 14:00,the chlorophyll fluorescence parameters showed a flat trend in moderate-and severe-etiolated camphor leaves .The average values of Fv/Fm in health camphor leaves were obviously higher than those in the etiolated camphor leaves .The maximal photochemical efficiency of PSⅡin the healthy camphor leaves was higher ,the average electron transfer rate and the potential activity of PSⅡshowed a descending trend .The daily average value of N P,Q in the etiolated camphora leaves was obviously higher than that in the healthy camphor leaves ,and increased with the increase of etiolation degree ,indicating that the more seriously the leaves were etiolated the higher proportion of light energy was absorbed by camphor leaves to avoid the destruction of photosynthetic tissue through hot dissipation .%对冬季不同黄化等级的香樟叶片主要叶绿素荧光参数的日变化进行了测定。结果表明:从08:00-16:00,健康和轻度黄化香樟F0(最小荧光)、Fm(最大荧光)、Fm′(光适应下的最大荧光)、Fv(可变荧光)、Fv/Fm (PSⅡ最大光能转换效率)、Fm/F0(电子传递效率)、Fv/F0(PSⅡ潜在活性)均呈现

  3. Fluorescence signals of quantum dots influenced by spatially controlled array structures

    International Nuclear Information System (INIS)

    Fluorescence signals of quantum dots (QDs) influenced by different array structures of gold-coated silicon nanorods (SiNRs) were investigated via experimental observations and two-dimensional (2D) finite element method (FEM) simulations. On the densest gold-coated SiNRs array structure, the highest QD fluorescence quenching rates were observed and on the sparsest array structure, the highest QD fluorescence enhancement rates were observed. By developing a new technique which obtains the optical image of the array structures without losing information about the QD locations, we were able to further investigate how the QD fluorescence is influenced by spatially controlled array structures.

  4. Efficient signal processing for time-resolved fluorescence detection of nitrogen-vacancy spins in diamond

    Science.gov (United States)

    Gupta, A.; Hacquebard, L.; Childress, L.

    2016-03-01

    Room-temperature fluorescence detection of the nitrogen-vacancy center electronic spin typically has low signal to noise, requiring long experiments to reveal an averaged signal. Here, we present a simple approach to analysis of time-resolved fluorescence data that permits an improvement in measurement precision through signal processing alone. Applying our technique to experimental data reveals an improvement in signal to noise equivalent to a 14% increase in photon collection efficiency. We further explore the dependence of the signal to noise ratio on excitation power, and analyze our results using a rate equation model. Our results provide a rubric for optimizing fluorescence spin detection, which has direct implications for improving precision of nitrogen-vacancy-based sensors.

  5. An Introduction to Chlorophyll Fluorescence

    NARCIS (Netherlands)

    Harbinson, J.; Rosenqvist, E.

    2003-01-01

    Photosynthesis is a physiological process that couples the energy of light to certain metabolic changes in biochemical reactions, via photochemical processess. It is the purpose of this chapter to lay out the basic physical and physiological processess associated with this coupling and to show how t

  6. Chlorophyll fluorescence characteristics of Amaranthus tricolor L.under high temperature stress%高温胁迫下苋菜的叶绿素荧光特性

    Institute of Scientific and Technical Information of China (English)

    陈梅; 唐运来

    2013-01-01

    为了探明高温胁迫对苋菜(Amaranthus tricolor L.)光合过程的影响,用不同温度(25、30、35、40、45℃)处理苋菜植株1h后,随即测定了其叶绿素荧光动力学参数和快速光响应曲线特征参数的变化.结果表明:40℃以上高温胁迫下,苋菜叶片的光系统Ⅱ(PSⅡ)潜在光化学效率(Fv/Fo)、最大光化学效率(Fv/Fm)下降;最大荧光(Fm)、光合电子传递速率(ETR)、PSⅡ实际光化学效率(Yield)、光化学淬灭系数(qP)也均有所下降;而初始荧光(F.)和非光化学淬灭系数(NPQ)在40℃以上高温胁迫下显著上升.叶绿素荧光快速光响应曲线测定结果表明,初始斜率α、最大相对电子传递速率ETRmax和半饱和光强Ik在40℃以上高温胁迫下有所下降.研究表明,40℃以上高温胁迫对苋菜的光能的吸收、转换、光合电子传递和强光耐受能力等均有一定的影响.%Amaranth (Amaranthus tricolor L.) plants were exposed to several temperature levels (25,30,35,40,and 45 ℃) for 1 h,and then,the characteristic parameters of chlorophyll fluorescence and the rapid light response curves of photosynthesis were measured,aimed to understand the effects of high temperature stress on the photosynthesis process of amaranth.High temperature stress (>40 ℃) decreased the maximum fluorescence (Fm),potential photochemical efficiency (Fv/Fo),and maximum photochemical efficiency of PS Ⅱ (Fv/Fm).Simultaneously,the electron transport rate (ETR),actual photochemical efficiency of PS Ⅱ (Yield),and photochemical quenching coefficient (qP) also had some decrease.In contrast,the initial fluorescence (Fo) and non-photochemical quenching coefficient (NPQ) were increased significantly.The initial slope rate (a),maximum apparent electron transport rates (ETRmax),and half-saturation light intensity (Ik) under high temperature stress also had some decline.These results indicated that the photosynthesis of A.tricolor plants was very sensitive to high

  7. Chlorophyll fluorescence of tropical tree species in a semi-deciduous forest gap Fluorescência da clorofila de espécies arbóreas tropicais em uma clareira de floresta semidecídua

    Directory of Open Access Journals (Sweden)

    Rafael Vasconcelos Ribeiro

    2004-02-01

    Full Text Available The characterization of different ecological groups in a forest formation/succession is unclear. To better define the different successional classes, we have to consider ecophysiological aspects, such as the capacity to use or dissipate the light energy available. The main objective of this work was to assess the chlorophyll fluorescence emission of tropical tree species growing in a gap of a semi-deciduous forest. Three species of different ecological groups were selected: Croton floribundus Spreng. (pioneer, P, Astronium graveolens Jacq. (early secondary, Si, and Esenbeckia febrifuga A. Juss. (late secondary, St. The potential (Fv/Fm and effective (deltaF/Fm' quantum efficiency of photosystem II, apparent electron transport rate (ETR, non-photochemical (qN and photochemical (qP quenching of fluorescence were evaluated, using a modulated fluorometer, between 7:30 and 11:00 h. Values of Fv/Fm remained constant in St, decreasing in P and Si after 9:30 h, indicating the occurrence of photoinhibition. Concerning the measurements taken under light conditions (deltaF/Fm', ETR, qP and qN, P and Si showed better photochemical performance, i.e., values of deltaF/Fm', ETR and qP were higher than St when light intensity was increased. Values of qN indicated that P and Si had an increasing tendency of dissipating the excess of energy absorbed by the leaf, whereas the opposite was found for St. The principal component analysis (PCA, considering all evaluated parameters, showed a clear distinction between St, P and Si, with P and Si being closer. The PCA results suggest that chlorophyll fluorescence may be a potential tool to differentiate tree species from distinct successional groups.A caracterização dos diferentes grupos ecológicos envolvidos nos processos de formação/sucessão florestal é ainda pouco precisa. Para melhor distinção das classes sucessionais deve-se levar em consideração aspectos ecofisiológicos, como a capacidade de

  8. Spermine detection via metal-mediated ethynylarene ‘turn-on’ fluorescence signaling

    OpenAIRE

    Fletcher, James T.; Bruck, Brent S.

    2015-01-01

    A dicarboxylated ethynylarene was shown to behave as a fluorescent chemosensor for millimolar concentrations of polyamines when mixed with Cd(II), Pb(II) or Zn(II) ions at micromolar concentrations. A bathochromic shift and intensification of fluorescence emission was observed with increasing amounts of metal ion in the presence of aqueous polyamines buffered at pH = 7.6. Such perturbations manifested as ‘turn-on’ signals from a ratiometric comparison of emission intensities at 390 nm versus ...

  9. Enhanced fluorescence cyanide detection at physiologically lethal levels: reduced ICT-based signal transduction.

    Science.gov (United States)

    Badugu, Ramachandram; Lakowicz, Joseph R; Geddes, Chris D

    2005-03-16

    Three water-soluble fluorescent probes have been specifically designed to determine free cyanide concentrations up to physiologically lethal levels, >20 microM. The probes have been designed in such a way as to afford many notable sensing features, which render them unique with regard to signal transduction, photophysical characteristics, and their application to physiological cyanide determination and safeguard. The probes are readily able to reversibly bind free aqueous cyanide with dissociation constants around 4 microM3. Subsequent cyanide binding modulates the intramolecular charge transfer within the probes, a change in the electronic properties within the probes, resulting in enhanced fluorescence optical signals as a function of increased solution cyanide concentration. The ground-state chelation with cyanide produces wavelength shifts, which also enable the probes to sense cyanide in both an excitation and emission ratiometric manner, in addition to enhanced fluorescence signaling. This has enabled a generic cyanide sensing platform to be realized that is not dependent on fluorescent probe concentration, probe photodegradation, or fluctuations in the intensity of any employed excitation sources, ideal for remote cyanide sensing applications. Further, the >600 nm fluorescence emission of the probes potentially allows for enhanced fluorescence ratiometric cyanide sensing in the optical window of tissues and blood, facilitating their use for the transdermal monitoring of cyanide for mammalian safeguard or postmortem in fire victims, both areas of active research. PMID:15755185

  10. The effects of UV radiation on photosynthesis estimated as chlorophyll fluorescence in Zygnemopsis decussata (Chlorophyta growing in a high mountain lake (Sierra Nevada, Southern Spain

    Directory of Open Access Journals (Sweden)

    Mayte MATA

    2009-08-01

    Full Text Available The effect of increased UV radiation on photosynthesis estimated as in vivo chlorophyll fluorescence i.e. optimal quantum yield (Fv/Fm and electron transport rate (ETR in the green filamentous alga Zygnemopsis decussata (Streptophyta, Zygnematales growing in the high mountain lake "La Caldera" (Sierra Nevada, Spain at 3050 m altitude was evaluated. Two sets of in situ experiments were conducted: (1 On July 2006, Fv/Fm was measured throughout the day at different depths (0.1, 0.25, 0.5 and 1 m and in the afternoon, ETR and phenolic compounds were determined. In addition, in order to analyze the effect of UV radiation, Fv/Fm was determined in algae incubated for 3 days at 0.5m under three different light treatments: PAR+UVA+UVB (PAB, PAR+UVA (PA and PAR (P. (2 On August 2007, Fv/Fm was determined under PAB, PA and P treatments and desiccation/rehydration conditions. Fv/Fm decreased in algae growing in surface waters (0.1 m but also at 1 m depth compared to that at 0.5 m depth. The decrease of Fv/Fm at noon due to photoinhibition was small (less than 10% except in algae growing at 1 m depth (44%. The maximal electron transport rate was 3.5-5 times higher in algae growing at 0.25-0.5 m respectively than that at 0.1 and 1 m depth. These results are related to the accumulation of phenolic compounds: i.e. the algae at 0.25-0.5 m presented respectively about a 3-5 times higher concentration of phenolic compounds than that of algae at 0.1-1 m depth. The protection mechanisms seem to be stimulated by UVB radiation, since Fv/Fm was higher in the presence of UVB (PAB treatment compared to PA or P treatments. UVA exerts the main photoinhibitory effect, not only at midday, but also in the afternoon. UVB radiation also had a protective effect in algae grown under desiccation conditions for three days. During re-hydration, the rapid increase of Fv/Fm (after 1 h was higher in the UVB-grown algae than in algae grown under UVA radiation. After 5 h, Fv/Fm values

  11. Development of output signal-to-noise ratio tester for microchannel plate and fluorescent screen component

    Science.gov (United States)

    Wu, Xinglin; Qiu, Yafeng; Zhou, Jin; Qian, Yunsheng

    The core components of Image intensifier is microchannel plate (MCP) and fluorescent screen component. The present paper deeply studies output signal-to-noise ratio (SNR) characteristics of MCP and fluorescent screen component. A tester system using to the evaluation of characteristics of the output SNR of MCP and fluorescent screen component, consists of a vacuum system, a surface electron source, mechanical mechanism components ,a high-voltage power supply system, a signal processing system, communication interfaces, a data acquisition and control system, computer system, and testing software. a hot cathode used as an electron source, generates a surface electron flow to provide the input signal. A photomultiplier tube is used to detection faceplate output brightness of the light spot. Then, the output SNR of MCP and fluorescent screen component is processed with a combination of methods of the hardware filter and digital filtering software. The output SNR of MCP and fluorescent screen component is measured under different conditions, and the results are analyzed. This test system Provide a technical to promote the image intensifier research, and experience to testing other parameters or in other areas of research.

  12. Parameter Difference of Chlorophyll Fluorescence in Leaves of Different Cultivars of Lycium barbarum%不同枸杞品种叶绿素荧光参数差异分析

    Institute of Scientific and Technical Information of China (English)

    杨娟; 王有科; 李捷; 陈娜; 李小刚; 张晓娜

    2014-01-01

    In this research,some cultivars of Lycium barbarum were taken as the materials.In the field experiment,the chlorophyll fluorescence parameters and the chlorophyll contents in the cultivars of L.barbarum were studied using the chlorophyll fluorescence measuring technique.The results revealed that the maximal photochemical efficiency of PS Ⅱ (Fv/Fm) and potential activity of PS Ⅱ (Fv/Fo) of Ningqi No.2 were remarkably higher than those of other three cultivars.The actual photosynthesis yield (Y(Ⅱ)),activity photosynthesis yield (Fv'/ Fm'),photochemical quenching (qP) and electron transport rate (ETR) were significantly different from different cultivars under a photo synthetically active radiation of 0-2 847 μmol · m-2 · s-1,and they were the highest in Ningqi No.2,followed by Mengqi No.1 and Damaye,and the lowest in Ningqi No.1.The initial slope α of fitting parameter ETR was similar to the change trend of ETR.The content of Chlorophyll a,Chlorophyll b and Chlorophyll a + b in Ningqi No.2 were the highest.There was an extremely significant or a significant positive correlation between chlorophyll a + b and Y(Ⅱ),Fv'/Fm',qP and ETR,but a negative correlation with NPQ.So it could be concluded that Ningqi No.2 had a higher physiological activity of PS Ⅱ and physiological basis of potential biomass,the photosynthesis capability of all the four cultivars was strong.The photochemical efficiency of Ningqi No.1 was weaker,and it was easy to suffer from photo inhibition at high light intensity.%在田间试验条件下,以宁杞1号、宁杞2号、大麻叶和蒙杞l号为材料,采用叶绿素荧光技术测定了不同枸杞品种的叶绿素荧光参数,并测定供试品种的叶绿素含量.结果表明:宁杞2号的PSⅡ最大光化学效率(Fv/Fm)和PSⅡ潜在活性(Fv/Fo)值显著高于其他3个品种.在不同光照强度(PAR,0~2 847 μmol·m-2·s-1)下,实际光合量子产量[Y(Ⅱ)]、有效光合量子产量(Fv'/Fm')、光化学淬灭系数(qP)

  13. Fluorescence signalling of the transition metal ions: Design strategy based on the choice of the fluorophore component

    Indian Academy of Sciences (India)

    N B Sankaran; S Banthia; A Samanta

    2002-12-01

    Transition metal ions are notorious for their fluorescence quenching abilities. In this paper, we discuss the design strategies for the development of efficient off-on fluorescence signalling systems for the transition metal ions. It is shown that even simple fluorophore-spacer-receptor systems can display excellent off-on fluorescence signalling towards the quenching metal ions when the fluorophore component is chosen judiciously.

  14. 竹炭有机肥对有机卷心菜叶绿素荧光特性和相对叶绿素含量的影响%Effect of bamboo charcoal organic fertilizer on chlorophyll fluores-cence characteristics and relative chlorophyll content of organic cab-bage

    Institute of Scientific and Technical Information of China (English)

    马锦丽; 黄鹤凤; 江洪; 舒海燕; 张金梦; 吴丹娜; 孙文文; 吴孟霖; 方成圆; 陈晓峰

    2015-01-01

    Selecting organic cabbage in Chongming of Shanghai dol y farm as the research object, and set up three bamboo charcoal organic fertilizer processing:BC180 (180 kg/20 m × 20 m), BC60 (60 kg/20 m × 20 m), CK (control), During July(Rosette period) and August(Fruit period) in 2014, its chlorophyl fluorescence kinetics parameter and relative chlorophyl content is determined by a random and relative method, in order to analyze the influence of bamboo charcoal organic fertilizer on the organic cabbage.The results showed that different growth period under the same processing, organic cabbage leaf blade light systemⅡ(PSⅡ), initial fluorescence (F0), the largest fluorescence (Fm), maximum photochemical efficiency (Fv/Fm), potential photosynthetic activity (Fv/F0), the actual photochemical efficiency (Yield) were rosette period > fruit period; Apparent photosynthetic electron transport rate (ETR), coefficient of photochemical quenching (qP) and relative chlorophyl content (SPAD) was fruit period>rosette period. The same growth period under different processing, Fv/Fm, Fv/F0, Yield, ETR, qP were increasing as fertilizer rate increasing, NPQ increases during rosette period, and became lower during knot bal period. Different growth period and fertilizer's interaction on Fm, Fv/Fm, Fv/F0, NPQ were very significant (P结球期;表观光合电子传递速率(ETR)、光化学淬灭系数(qP)、相对叶绿素含量(SPAD)为结球期>莲座期。同一生长期不同处理下,Fv/Fm、Fv/F0、Yield、ETR、qP均是随着施肥量增加而增加,NPQ则为莲座期增加,结球期又降低。不同生长期不同施肥量交互作用对Fm、Fv/Fm、Fv/F0、NPQ影响极显著(P<0.01),对qP影响显著(P<0.05)。这说明增施竹炭有机肥对有机卷心菜叶绿素荧光指标和相对叶绿素含量有显著影响,且BC60处理下更有助于其光合固碳,增加产量,符合低碳有机农业宗旨。

  15. Analysis of initial chlorophyll fluorescence induction kinetics in chloroplasts in terms of rate constants of donor side quenching release and electron trapping in photosystem II

    NARCIS (Netherlands)

    Vredenberg, W.J.

    2008-01-01

    The fluorescence induction F(t) of dark-adapted chloroplasts has been studied in multi-turnover 1 s light flashes (MTFs). A theoretical expression for the initial fluorescence rise is derived from a set of rate equations that describes the sequence of transfer steps associated with the reduction of

  16. Spatial Four Wave Mixing, Probe Images, and Fluorescence Signals in Dressed Three-Level System

    Science.gov (United States)

    Lan, Huayan; Sun, Jia; Wu, Zhenkun; Zhang, Dan; Zhang, Yiqi; Zheng, Huaibin; Zhang, Yanpeng

    2013-10-01

    We investigate the spatial images of the probe, generated four wave mixing (FWM) signal and the accompanying fluorescence spectrum signal simultaneously in FWM process in a cascade three-level atomic system for the first time. We experimentally observe and theoretically investigate the three spectrum signals versus the probe field as well as the dressing field frequency detunings. Utilizing the experimental results of spectrum signals, the cross phase modulation and the relative position between the weak and strong beams, we analyze the characteristics indicated in the spatial images of probe transmission and FWM, such as focusing or defocusing, shift and splitting in detail. Such studies can be used in all-optical controlled spatial signal transmission.

  17. 基于叶绿素荧光光谱的生菜硝酸盐含量检测%Detection of nitrate content in lettuce based on chlorophyll fluorescence spectrum

    Institute of Scientific and Technical Information of China (English)

    王琳琳; 于海业; 张蕾; 赵红星

    2016-01-01

    为了寻求生菜叶片硝酸盐含量的快速无损检测方法,该文利用叶绿素荧光光谱分析技术对生菜(Lactuca sativa L.)叶片硝酸盐含量进行检测研究。对比及分析500~550、650~715和715~800 nm 3个波段的叶绿素荧光光谱特征参数与生菜叶片硝酸盐含量的关系,得出650~715 nm 波段的叶绿素荧光光谱特征参数与生菜叶片硝酸盐含量之间线性关系显著,决定系数 R2为0.816,标准误差为0.147,以此建立的回归模型能够很好地反映生菜叶片硝酸盐含量与叶绿素荧光光谱特征参数的关系;将同批进行试验的30个样本作为回归方程的校验集,进行模型验证,预测值与实测值之间决定系数R2为0.752,表明回归模型对生菜叶片硝酸盐含量有良好的预测效果。研究结果为生菜叶片硝酸盐含量的快速无损检测提供参考。%With the development of spectral technology, many researchers have done a lot of research on the nondestructive testing methods of nitrate content in leaves and have achieved some results. However, most of the studies have used visible and near infrared spectroscopy or mid infrared spectroscopy technology, and the chlorophyll fluorescence spectrum technology is still not used. Therefore, this paper used chlorophyll fluorescence spectrum analysis technology to study the relationship between nitrate content and fluorescence spectrum. With aerosol cultured lettuce as the research object, the chlorophyll fluorescence spectrum characteristic parameters were extracted to establish the function relationship between the characteristic parameters of chlorophyll fluorescence spectrum and the nitrate content of lettuce leaves, which laid a theoretical foundation for the rapid and nondestructive detection of nitrate content in lettuce leaves. The peak values of fluorescence intensity of 500-550, 650-715 and 715-800 nm were the characteristic parameters of chlorophyll fluorescence

  18. Larval vision contributes to gregarious settlement in barnacles: adult red fluorescence as a possible visual signal

    KAUST Repository

    Matsumura, K.

    2014-02-26

    Gregarious settlement, an essential behavior for many barnacle species that can only reproduce by mating with a nearby barnacle, has long been thought to rely on larval ability to recognize chemical signals from conspecifics during settlement. However, the cyprid, the settlement stage larva in barnacles, has one pair of compound eyes that appear only at the late nauplius VI and cyprid stages, but the function(s) of these eyes remains unknown. Here we show that cyprids of the intertidal barnacle Balanus (=Amphibalanus) amphitrite can locate adult barnacles even in the absence of chemical cues, and prefer to settle around them probably via larval sense of vision. We also show that the cyprids can discriminate color and preferred to settle on red surfaces. Moreover, we found that shells of adult B. amphitrite emit red auto-fluorescence and the adult extracts with the fluorescence as a visual signal attracted cyprid larvae to settle around it. We propose that the perception of specific visual signals can be involved in behavior of zooplankton including marine invertebrate larvae, and that barnacle auto-fluorescence may be a specific signal involved in gregarious larval settlement.

  19. The chloroplast signal recognition particle (CpSRP) pathway as a tool to minimize chlorophyll antenna size and maximize photosynthetic productivity.

    Science.gov (United States)

    Kirst, Henning; Melis, Anastasios

    2014-01-01

    The concept of the Truncated Light-harvesting chlorophyll Antenna (TLA) size, as a tool by which to maximize sunlight utilization and photosynthetic productivity in microalgal mass cultures or high-density plant canopies, is discussed. TLA technology is known to improve sunlight-to-product energy conversion efficiencies and is hereby exemplified by photosynthetic productivity estimates of wild type and a TLA strain under simulated mass culture conditions. Recent advances in the generation of TLA-type mutants by targeting genes of the chloroplast signal-recognition particle (CpSRP) pathway, affecting the thylakoid membrane assembly of light-harvesting proteins, are also summarized. Two distinct CpSRP assembly pathways are recognized, one entailing post-translational, the other a co-translational mechanism. Differences between the post-translational and co-translational integration mechanisms are outlined, as these pertain to the CpSRP-mediated assembly of thylakoid membrane protein complexes in higher plants and green microalgae. The applicability of the CpSRP pathway genes in efforts to generate TLA-type strains with enhanced solar energy conversion efficiency in photosynthesis is evaluated.

  20. Comparison of a compatible and an incompatible pepper-tobamovirus interaction by biochemical and non-invasive techniques: chlorophyll a fluorescence, isothermal calorimetry and FT-Raman spectroscopy.

    Science.gov (United States)

    Rys, Magdalena; Juhász, Csilla; Surówka, Ewa; Janeczko, Anna; Saja, Diana; Tóbiás, István; Skoczowski, Andrzej; Barna, Balázs; Gullner, Gábor

    2014-10-01

    Leaves of a pepper cultivar harboring the L(3) resistance gene were inoculated with Obuda pepper virus (ObPV), which led to the appearance of hypersensitive necrotic lesions approx. 72 h post-inoculation (hpi) (incompatible interaction), or with Pepper mild mottle virus (PMMoV) that caused no visible symptoms on the inoculated leaves (compatible interaction). ObPV inoculation of leaves resulted in ion leakage already 18 hpi, up-regulation of a pepper carotenoid cleavage dioxygenase (CCD) gene from 24 hpi, heat emission and declining chlorophyll a content from 48 hpi, and partial desiccation from 72 hpi. After the appearance of necrotic lesions a strong inhibition of photochemical energy conversion was observed, which led to photochemically inactive leaf areas 96 hpi. However, leaf tissues adjacent to these inactive areas showed elevated ΦPSII and Fv/Fm values proving the advantage of chlorophyll a imaging technique. PMMoV inoculation also led to a significant rise of ion leakage and heat emission, to the up-regulation of the pepper CCD gene as well as to decreased PSII efficiency, but these responses were much weaker than in the case of ObPV inoculation. Chlorophyll b and total carotenoid contents as measured by spectrophotometric methods were not significantly influenced by any virus inoculations when these pigment contents were calculated on leaf surface basis. On the other hand, near-infrared FT-Raman spectroscopy showed an increase of carotenoid content in ObPV-inoculated leaves suggesting that the two techniques detect different sets of compounds.

  1. [Rapid and high throughput measurement of lipase thermo-stability through ANS fluorescence signal assay].

    Science.gov (United States)

    Feng, Weizong; Lin, Junhan; Cai, Shaoli; Zou, Youtu; Chen, Guoren; Huang, Ping; Lin, Yajing; Wang, Bingbing; Lin, Lin

    2011-04-01

    We have developed a rapid and high throughput lipase-ANS (8-Anilino-l-naphthalenesulfonic acid) assay to evaluate the thermo-stability of lipases based on the ANS fluorescence signal's increasing and shifting when this small fluorescence probes binds to lipase. The testing lipase samples were incubated at a temperature range of 25 degrees C to 65 degrees C for 30 min before mixed with ANS solution (0.20 mg/mL lipase and 0.05 mmol/L ANS in the buffer of 20 mmol/L Tris-HCl, 100 mmol/L NaCl, pH 7.2) in a cuvette or microplate. Fluorescence signals of the samples were measured at EX 378 nm, EM 465 nm with a fluorescence photometer or a plate reader, and Tm was calculated with the software of GraphPad Prism5.0. The Tm values of several mutants of Penicillium expansum lipase (PEL) were measured with this ANS assay and conventional method simultaneously and the results show that Tm values are comparative and consistent between these methods, suggesting that the lipase-ANS assay is a reliable, rapid and high throughput method for lipase thermo-stability measurement. PMID:21847993

  2. Correlation functions in resonance fluorescence with spectral resolution: Signal-processing approach

    Science.gov (United States)

    Shatokhin, Vyacheslav N.; Kilin, Sergei Ya.

    2016-09-01

    In the framework of the signal processing approach to single-atom resonance fluorescence with spectral resolution, we diagrammatically derive an analytical formula for arbitrary-order spectral correlation functions of the scattered fields that pass through Fabry-Perot interferometers. Our general expression is then applied to study correlation signals in the limit of well separated spectral lines of the resonance fluorescence spectrum. In particular, we study the normalized second-order temporal intensity correlation functions in the case of the interferometers tuned to the components of the spectrum and obtain interferential corrections to the approximate results derived in the secular limit. In addition, we explore purely spectral correlations and show that they can fully be understood in terms of the two-photon cascades down the dressed state ladder.

  3. Absorption and Distribution of Na+, K+ and Chlorophyll Fluorescence in Castor under Salt Stress%盐胁迫对蓖麻Na+、K+吸收分布特点和叶绿素荧光的影响

    Institute of Scientific and Technical Information of China (English)

    张(丰 刀)(女); 姚舸; 钦佩

    2008-01-01

    [Objective] The aim of this study is to reveal the salt resistance of castor. [Method] Under salt stress, the growth, osmotic potential, chlorophyll fluorescence parameters, Na+ and K+ uptakes and transports in the seedlings of two Ricinus communis varieties (cultivar saline-alkali land), were comparatively studied. [Result] Wild castor preformed better in halophilism than that of cultivar castor Zibi 6 under the NaCl treatment. One of the salt tolerant mechanisms of castor is to improve K+ uptake and transport to overground portion, thus to maintain K+/Na+ homeostasis in leaves; on the other hand, the high stability of Photoreaction System Ⅱ (PS Ⅱ) plays a key role in maintaining the leaf photosynthetic rate under salt stress. [Conclusion] The results of this study provided theoretical basis for the extension and application of castor in saline beach.

  4. Endolithic chlorophyll d-containing phototrophs

    DEFF Research Database (Denmark)

    Behrendt, Lars; Larkum, Anthony W D; Norman, Anders;

    2011-01-01

    Cyanobacteria in the genus Acaryochloris are the only known oxyphototrophs that have exchanged chlorophyll a (Chl a) with Chl d as their primary photopigment, facilitating oxygenic photosynthesis with near infrared (NIR) light. Yet their ecology and natural habitats are largely unknown. We used...... hyperspectral and variable chlorophyll fluorescence imaging, scanning electron microscopy, photopigment analysis and DNA sequencing to show that Acaryochloris-like cyanobacteria thrive underneath crustose coralline algae in a widespread endolithic habitat on coral reefs. This finding suggests an important role...

  5. Tyramide Signal Amplification: Fluorescence In Situ Hybridization for Identifying Homoeologous Chromosomes.

    Science.gov (United States)

    Fominaya, Araceli; Loarce, Yolanda; González, Juan M; Ferrer, Esther

    2016-01-01

    Tyramide signal amplification (TSA) fluorescence in situ hybridization (FISH) has been shown as a valuable molecular tool for visualizing specific amplified DNA sequences in chromosome preparations. This chapter describes how to perform TSA-FISH, paying special interest to its two critical steps: probe generation and metaphase plate generation. The potential of physically mapping 12S-globulin sequences by TSA-FISH as a means of identifying homeology among chromosome regions of Avena species was tested and is discussed. PMID:27511165

  6. Bright fluorescence monitoring system utilizing Zoanthus sp. green fluorescent protein (ZsGreen for human G-protein-coupled receptor signaling in microbial yeast cells.

    Directory of Open Access Journals (Sweden)

    Yasuyuki Nakamura

    Full Text Available G-protein-coupled receptors (GPCRs are currently the most important pharmaceutical targets for drug discovery because they regulate a wide variety of physiological processes. Consequently, simple and convenient detection systems for ligands that regulate the function of GPCR have attracted attention as powerful tools for new drug development. We previously developed a yeast-based fluorescence reporter ligand detection system using flow cytometry. However, using this conventional detection system, fluorescence from a cell expressing GFP and responding to a ligand is weak, making detection of these cells by fluorescence microscopy difficult. We here report improvements to the conventional yeast fluorescence reporter assay system resulting in the development of a new highly-sensitive fluorescence reporter assay system with extremely bright fluorescence and high signal-to-noise (S/N ratio. This new system allowed the easy detection of GPCR signaling in yeast using fluorescence microscopy. Somatostatin receptor and neurotensin receptor (implicated in Alzheimer's disease and Parkinson's disease, respectively were chosen as human GPCR(s. The facile detection of binding to these receptors by cognate peptide ligands was demonstrated. In addition, we established a highly sensitive ligand detection system using yeast cell surface display technology that is applicable to peptide screening, and demonstrate that the display of various peptide analogs of neurotensin can activate signaling through the neurotensin receptor in yeast cells. Our system could be useful for identifying lead peptides with agonistic activity towards targeted human GPCR(s.

  7. Resolution of heterogeneous fluorescence emission signals and decay lifetime measurement on fluorochrome-labeled cells by phase-sensitive FCM

    Energy Technology Data Exchange (ETDEWEB)

    Steinkamp, J.A.; Crissman, H.A.

    1993-01-01

    A phase-sensitive flow cytometer has been developed to resolve signals from heterogeneous fluorescence emission spectra and quantify fluorescence decay times on cells labeled with fluorescent dyes. This instrument combines flow cytometry (FCM) and fluorescence spectroscopy measurement principles to provide unique capabilities for making phase-resolved measurements on single cells in flow, while preserving conventional FCM measurement capabilities. Stained cells are analyzed as they pass through an intensity-modulated (sinusoid) laser excitation beam. Fluorescence is measured orthogonally using a s barrier filter to block scattered laser excitation light, and a photomultiplier tube detector output signals, which are shifted in phase from a reference signal and amplitude demodulated, are processed by phase-sensitive detection electronics to resolve signals from heterogeneous emissions and quantify decay lifetimes directly. The output signals are displayed as frequency distribution histograms and bivariate diagrams using a computer-based data acquisition system. Results have demonstrated signal phase shift, amplitude demodulation, and average measurement of fluorescence lifetimes on stained cells; a detection limit threshold of 300 to 500 fluorescein isothiocyanate (FITC); fluorescence measurement precision of 1.3% on alignment fluorospheres and 3.4% on propidium iodide (PI)-stained cells; the resolution of PI and FITC signals from cells stainedin combination with PI and FITC, based on differences in their decay lifetimes; and the ability to measure single decay nines by the two-phase, phase comparator, method.

  8. Resolution of heterogeneous fluorescence emission signals and decay lifetime measurement on fluorochrome-labeled cells by phase-sensitive FCM

    Energy Technology Data Exchange (ETDEWEB)

    Steinkamp, J.A.; Crissman, H.A.

    1993-02-01

    A phase-sensitive flow cytometer has been developed to resolve signals from heterogeneous fluorescence emission spectra and quantify fluorescence decay times on cells labeled with fluorescent dyes. This instrument combines flow cytometry (FCM) and fluorescence spectroscopy measurement principles to provide unique capabilities for making phase-resolved measurements on single cells in flow, while preserving conventional FCM measurement capabilities. Stained cells are analyzed as they pass through an intensity-modulated (sinusoid) laser excitation beam. Fluorescence is measured orthogonally using a s barrier filter to block scattered laser excitation light, and a photomultiplier tube detector output signals, which are shifted in phase from a reference signal and amplitude demodulated, are processed by phase-sensitive detection electronics to resolve signals from heterogeneous emissions and quantify decay lifetimes directly. The output signals are displayed as frequency distribution histograms and bivariate diagrams using a computer-based data acquisition system. Results have demonstrated signal phase shift, amplitude demodulation, and average measurement of fluorescence lifetimes on stained cells; a detection limit threshold of 300 to 500 fluorescein isothiocyanate (FITC); fluorescence measurement precision of 1.3% on alignment fluorospheres and 3.4% on propidium iodide (PI)-stained cells; the resolution of PI and FITC signals from cells stainedin combination with PI and FITC, based on differences in their decay lifetimes; and the ability to measure single decay nines by the two-phase, phase comparator, method.

  9. Response of Water Stress on Chlorophyll Fluorescence Parameters of Tomato Seedlings%番茄幼苗叶绿素荧光参数对水分胁迫的响应

    Institute of Scientific and Technical Information of China (English)

    须晖; 高洁; 王蕊; 李天来; 马健; 刘满昌

    2011-01-01

    To study the response of tomato seedlings to water stress, the effect on chlorophyll fluorescence properties and chlorophyll content and the relative leaf water content. The results suggested that water stress lead to the maximum quantum efficiency of PSII photochemistry (Fv/Fm), the photochemical quenching (qL)and the linear electron transport rate (ETR) decreased gradually. In contrast, the non photochemical quenching (NPQ) rose gradually. Chlorophyll fluorescence parameters had dash jump phenomena on moderate water stress (the fourth day). Results showed a high correlation (-0.83*) between the decreasing of soil water content (SWC)and NPQ. Hence, NPQ can be an indicator as a guide for irrigation. When NPQ was 2.095, SWC was lower than 32.1%, tomato seedlings were affect on water stress and should be irrigation timely.%以5叶1心期番茄品种‘辽园多丽'为试材,研究番茄幼苗叶绿素荧光特性、叶绿素含量以及叶片相对含水量对水分胁迫的生理响应.结果表明,水分胁迫导致叶绿素荧光参数Fy/Fm、qL、ETR下降,NPQ上升;在轻度水分胁迫下,叶绿素荧光各参数值均有突跃现象.在整个水分胁迫过程中番茄幼苗叶片相对含水量及叶绿素含量均呈下降趋势.NPQ与基质含水量的变化密切相关,相关系数为-0.83',表明荧光参数NPQ可以作为指导灌溉的一个指标.当NPO为2.0975时,基质含水量降到31.2%,番茄幼苗生长受到水分胁迫的影响,应及时灌溉.

  10. Tracking quasi-stationary flow of weak fluorescent signals by adaptive multi-frame correlation.

    Science.gov (United States)

    Ji, L; Danuser, G

    2005-12-01

    We have developed a novel cross-correlation technique to probe quasi-stationary flow of fluorescent signals in live cells at a spatial resolution that is close to single particle tracking. By correlating image blocks between pairs of consecutive frames and integrating their correlation scores over multiple frame pairs, uncertainty in identifying a globally significant maximum in the correlation score function has been greatly reduced as compared with conventional correlation-based tracking using the signal of only two consecutive frames. This approach proves robust and very effective in analysing images with a weak, noise-perturbed signal contrast where texture characteristics cannot be matched between only a pair of frames. It can also be applied to images that lack prominent features that could be utilized for particle tracking or feature-based template matching. Furthermore, owing to the integration of correlation scores over multiple frames, the method can handle signals with substantial frame-to-frame intensity variation where conventional correlation-based tracking fails. We tested the performance of the method by tracking polymer flow in actin and microtubule cytoskeleton structures labelled at various fluorophore densities providing imagery with a broad range of signal modulation and noise. In applications to fluorescent speckle microscopy (FSM), where the fluorophore density is sufficiently low to reveal patterns of discrete fluorescent marks referred to as speckles, we combined the multi-frame correlation approach proposed above with particle tracking. This hybrid approach allowed us to follow single speckles robustly in areas of high speckle density and fast flow, where previously published FSM analysis methods were unsuccessful. Thus, we can now probe cytoskeleton polymer dynamics in living cells at an entirely new level of complexity and with unprecedented detail.

  11. Beyond "turn-on" readout: from zero background to signal amplification by combination of magnetic separation and plasmon enhanced fluorescence.

    Science.gov (United States)

    Gong, Suqin; Xia, Yunsheng

    2016-08-11

    By magnetic separation and subsequent plasmon enhanced fluorescence, an assay platform with a signal output from completely "zero" background to fluorescence amplification is achieved, using quantum dots as reporters. So, it well breaks through the conventional "turn-on" strategy in both lower and upper limits. The sensitivity for hyaluronidase sensing is enhanced 10(4)-10(6) times as compared with previous fluorescence methods. PMID:27398675

  12. Chlorophylls - natural solar cells

    CERN Document Server

    Jantschi, Lorentz; Balan, Mugur C; Sestras, Radu E

    2011-01-01

    A molecular modeling study was conducted on a series of six natural occurring chlorophylls. Quantum chemistry calculated orbital energies were used to estimate frequency of transitions between occupied molecular orbital and unoccupied molecular orbital energy levels of chlorophyll molecules in vivo conditions in standard (ASTMG173) environmental conditions. Obtained results are in good agreement with energies necessary to fix the Magnesium atom by chlorophyll molecules and with occurrence of chlorophylls in living vegetal organisms.

  13. 叶绿素荧光技术在珊瑚礁研究中的应用%Application of Chlorophyll Fluorescence Technique in the Study of Coral Reefs

    Institute of Scientific and Technical Information of China (English)

    周洁; 施祺; 余克服

    2011-01-01

    Mutualism between corals and their zooxanthellae is the essential feature of reef formation. Through performing photosynthesis, zooxanthellae nourish the host coral as well as help it deposit its skeleton. Thus, the chlorophyll fluorescence technique, previously being used in the study of photosynthesis of plants, including algae, can shed light on the research of coral reefs, and has been widely spread in the field. Its application contains several aspects: revealing of photophysiology principles of symbiont dinoflagelates, explanation of the machanism of coral bleaching, early warning of coral bleaching, monitoring the responses of coral to pollutions, monitoring the effects of turbidity to coral growth, and exploring the ecological pattern of coral reef. PAM fluorometry has good potential for such applications, as fluorescence yield is a sensitive, non-invasive indicator of sublethal stress. Therefore, the study of physiological ecology of scleractinian corals may be more effective in the aid of chlorophyll fluorescence technique.%珊瑚礁生态系统最基本的生态特征是虫黄藻与珊瑚虫的共生,虫黄藻的光合作用在珊瑚礁生态系统中发挥着重要作用,因此用于测定植物光合作用的叶绿素荧光技术在认识珊瑚礁生态系统中得到越来越广泛的应用.应用方面主要包括:①揭示珊瑚共生藻光生理学原理;②探索珊瑚白化的机制;③监测及预警珊瑚白化事件;④研究珊瑚对污染的响应;⑤监测珊瑚对水体浑浊的响应;⑥探寻珊瑚礁生态模式.叶绿素荧光技术具有快速、灵敏和非破坏性测量等优点,在造礁珊瑚生理生态研究方面将有广阔的应用前景.

  14. Visualization and quantification of APP intracellular domain-mediated nuclear signaling by bimolecular fluorescence complementation.

    Directory of Open Access Journals (Sweden)

    Florian Riese

    Full Text Available BACKGROUND: The amyloid precursor protein (APP intracellular domain (AICD is released from full-length APP upon sequential cleavage by either α- or β-secretase followed by γ-secretase. Together with the adaptor protein Fe65 and the histone acetyltransferase Tip60, AICD forms nuclear multiprotein complexes (AFT complexes that function in transcriptional regulation. OBJECTIVE: To develop a medium-throughput machine-based assay for visualization and quantification of AFT complex formation in cultured cells. METHODS: We used cotransfection of bimolecular fluorescence complementation (BiFC fusion constructs of APP and Tip60 for analysis of subcellular localization by confocal microscopy and quantification by flow cytometry (FC. RESULTS: Our novel BiFC-constructs show a nuclear localization of AFT complexes that is identical to conventional fluorescence-tagged constructs. Production of the BiFC signal is dependent on the adaptor protein Fe65 resulting in fluorescence complementation only after Fe65-mediated nuclear translocation of AICD and interaction with Tip60. We applied the AFT-BiFC system to show that the Swedish APP familial Alzheimer's disease mutation increases AFT complex formation, consistent with the notion that AICD mediated nuclear signaling mainly occurs following APP processing through the amyloidogenic β-secretase pathway. Next, we studied the impact of posttranslational modifications of AICD on AFT complex formation. Mutation of tyrosine 682 in the YENPTY motif of AICD to phenylalanine prevents phosphorylation resulting in increased nuclear AFT-BiFC signals. This is consistent with the negative impact of tyrosine phosphorylation on Fe65 binding to AICD. Finally, we studied the effect of oxidative stress. Our data shows that oxidative stress, at a level that also causes cell death, leads to a reduction in AFT-BiFC signals. CONCLUSION: We established a new method for visualization and FC quantification of the interaction between

  15. Effect of chelating agents and metal ions on nickel bioavailability and chlorophyll fluorescence response in wheat- An approach for attenuation of Ni stress

    Directory of Open Access Journals (Sweden)

    Nilima Patnaik

    2012-08-01

    Full Text Available The objectives of the study are to analyze the physiological changes, biochemical alterations and attenuation of nickel toxicity effects in wheat seedlings under combined applications of Ni ions, metal chelators (EDTA/Citric Acid and metal ions (Zn2+ /Mg2+. Wheat (Triticum aestivum L cv UP262 seedlings were grown hydroponically using different concentrations of Ni up to 7 days along with chelators and metal ions for study. The seedling growth was maximum with NiCl2–Zn2+ (100μM and minimum with NiCl2–EDTA (100μM treatments. Total chlorophyll content was maximum in the seedlings treated with NiCl2-Zn2+ (100μM and minimum in NiCl2-EDTA (100μM treatments. NiCl2–EDTA (100μM showed less Fo and Fm values and therefore, a trend in the decrease in OJIP transient indicates the maximum alteration of photochemical activity of PS-II in presence of NiCl2–EDTA (100μM treatment. Similar observation was found by NiCl2 –EDTA (200μM treatment where Fo and Fm values were noted to decline. High nickel content in roots of the seedlings was noted as compared to shoots.

  16. Impact of salt stress (NaCl on growth, chlorophyll content and fluorescence of Tunisian cultivars of chili pepper (Capsicum frutescens L.

    Directory of Open Access Journals (Sweden)

    Kaouther Zhani

    2012-11-01

    Full Text Available Salinity is considered as the most important abiotic stress limiting crop production and plants are known to be able continuing survive under this stress by involving many mechanisms. In this content, the present study was carried out to evaluate the impact of NaCl on some physiological and biochemical parameters in five Tunisian chili pepper (Capsicum frutescens L. cultivars: Tebourba (Tb, Somaa (Sm, Korba (Kb, Awald Haffouzz (AW and Souk jedid (Sj. Thus, an experiment of five months was carried out under greenhouse at Higher Institute of Agronomy, Chott Meriem, Tunisia and stress is induced by NaCl at 7 concentrations (0, 2, 4, 6, 8, 10 and 12g/l. Results showed that increasing salinity stress, for all cultivars, had a negative impact on roots (length, fresh and dry weights and leaves (number and area. Also, chlorophyll (a and b amount in addition to quantium yield (Fv/Fm decreased significantly. However, biosynthesis of proline in leaves is activated. Awlad Haffouzz and Korba cultivars succefully tolerated highest salinity level by accumulating more proline in leaves and maintaining usually higher values in all parameters in opposition to Souk jedid cultivar. Taken together, our data partly explain the mechanism used to ovoid salt stress by pepper plants when excessive in the culture medium.

  17. Recognition- and reactivity-based fluorescent probes for studying transition metal signaling in living systems.

    Science.gov (United States)

    Aron, Allegra T; Ramos-Torres, Karla M; Cotruvo, Joseph A; Chang, Christopher J

    2015-08-18

    Metals are essential for life, playing critical roles in all aspects of the central dogma of biology (e.g., the transcription and translation of nucleic acids and synthesis of proteins). Redox-inactive alkali, alkaline earth, and transition metals such as sodium, potassium, calcium, and zinc are widely recognized as dynamic signals, whereas redox-active transition metals such as copper and iron are traditionally thought of as sequestered by protein ligands, including as static enzyme cofactors, in part because of their potential to trigger oxidative stress and damage via Fenton chemistry. Metals in biology can be broadly categorized into two pools: static and labile. In the former, proteins and other macromolecules tightly bind metals; in the latter, metals are bound relatively weakly to cellular ligands, including proteins and low molecular weight ligands. Fluorescent probes can be useful tools for studying the roles of transition metals in their labile forms. Probes for imaging transition metal dynamics in living systems must meet several stringent criteria. In addition to exhibiting desirable photophysical properties and biocompatibility, they must be selective and show a fluorescence turn-on response to the metal of interest. To meet this challenge, we have pursued two general strategies for metal detection, termed "recognition" and "reactivity". Our design of transition metal probes makes use of a recognition-based approach for copper and nickel and a reactivity-based approach for cobalt and iron. This Account summarizes progress in our laboratory on both the development and application of fluorescent probes to identify and study the signaling roles of transition metals in biology. In conjunction with complementary methods for direct metal detection and genetic and/or pharmacological manipulations, fluorescent probes for transition metals have helped reveal a number of principles underlying transition metal dynamics. In this Account, we give three recent

  18. 增强UV-B辐射对水稻叶绿素荧光特性的影响%Influence of Enhanced UV-B Radiation on Chlorophyll Fluorescence Characteristics of Rice

    Institute of Scientific and Technical Information of China (English)

    乔媛; 殷红; 李虎; 杨振兴; 高敏

    2014-01-01

    以沈农265水稻为试材,自然光为对照,研究了2种增强紫外辐射处理下(分别增加5%和10%),水稻不同生育时期光合色素含量和叶绿素荧光动力学参数的变化特征。研究结果显示,两处理下的叶绿素含量在拔节期减少最多,叶绿素a分别下降13.87%和23.30%,叶绿素b分别下降10.76%和17.70%;而类胡萝卜素含量均有所增加,其中抽穗期增幅最大,分别比对照增加了21.55%和31.02%。2种处理下的PSⅡ原初光能转换效率( Fv/Fm )在灌浆期下降最多,分别比对照下降了4.4%和7.83%;PSⅡ潜在活性(Fv/Fo)也比对照降低了9.02%和17.03%;实际量子产量(ΦPSⅡ)在抽穗期降幅较大,但处理间差异不显著(P<0.05);2种处理下的光化学荧光淬灭系数(qP)均有所降低,且降幅随生育进程逐渐减小;2种处理下的非光化学荧光淬灭( NPQ)在各生育时期的变化截然相反,分别比对照升高和降低。%It was used to investigate the contents of photosynthetic pigment and the characteristics of chloro-phyll fluorescence kinetics parameters in the different growth stages of rice ( Shennong 265 ) at different treatments (UV radiation intensity increased by 5% and 10% respectively),compared with natural lighting. Results showed that the contents of chlorophyll-a and chlorophyll-b were diminished significantly in the jointing stage. The content of chlorophyll-a was diminished by 13. 87% and 23. 30% respectively. The content of chlorophyll-b was diminished by 10. 76% and 17. 70% respectively. The contents of carotenoids were increased by 21. 55% and 31. 02% respec-tively,especially in the heading stage. The intrinsic photochemical efficiency (Fv/Fm) of two treatments was dimin-ished by 4. 4% and 7. 83% respectively in the filling stage,and the potential activities (Fv/Fo) were diminished by 9. 02% and 17. 03% respectively. Decreasing amplitude of effective quantum yield (ΦPSⅡ) in the heading stage was

  19. Determining Photosynthetic Parameters from Leaf CO2 Exchange and Chlorophyll Fluorescence (Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Specificity Factor, Dark Respiration in the Light, Excitation Distribution between Photosystems, Alternative Electron Transport Rate, and Mesophyll Diffusion Resistance.

    Science.gov (United States)

    Laisk, A.; Loreto, F.

    1996-03-01

    Using simultaneous measurements of leaf gas exchange and chlorophyll fluorescence, we determined the excitation partitioning to photosystem II (PSII), the CO2/O2 specificity of ribulose-1,5-bisphosphate carboxylase/oxygenase, the dark respiration in the light, and the alternative electron transport rate to acceptors other than bisphosphoglycerate, and the transport resistance for CO2 in the mesophyll cells for individual leaves of herbaceous and tree species. The specificity of ribulose-1,5-bisphosphate carboxylase/oxygenase for CO2 was determined from the slope of the O2 dependence of the CO2 compensation point between 1.5 and 21% O2. Its value, on the basis of dissolved CO2 and O2 concentrations at 25.5[deg]C, varied between 86 and 89. Dark respiration in the light, estimated from the difference between the CO2 compensation point and the CO2 photocompensation point, was about 20 to 50% of the respiration rate in the dark. The excitation distribution to PSII was estimated from the extrapolation of the dependence of the PSII quantum yield on F/Fm to F = 0, where F is steady-state and Fm is pulse-satuarated fluorescence, and varied between 0.45 and 0.6. The alternative electron transport rate was found as the difference between the electron transport rates calculated from fluorescence and from gas exchange, and at low CO2 concentrations and 10 to 21% O2, it was 25 to 30% of the maximum electron transport. The calculated mesophyll diffusion resistance accounted for about 20 to 30% of the total mesophyll resistance, which also includes carboxylation resistance. Whole-leaf photosynthesis is limited by gas phase, mesophyll diffusion, and carboxylation resistances in nearly the same proportion in both herbaceous species and trees. PMID:12226229

  20. Chlorophyll in tomato seeds: marker for seed performance?

    NARCIS (Netherlands)

    Suhartanto, M.R.

    2002-01-01

    Using Xe-PAM, laser induced fluorometry and high performance liquid chromatography we found that chlorophyll was present in young tomato (cv. Moneymaker) seeds and was degraded during maturation. Fluorescence microscopy and imaging showed that the majority of chlorophyll is located in the seed coat

  1. Fluorescência da clorofila a em folhas de tangerineira 'Ponkan' e limeira ácida 'Tahiti' submetidas ao estresse hídrico Chlorophyll a fluorescence in leaves of 'Ponkan' mandarin and the 'Tahiti' acid lime submitted to water stress

    Directory of Open Access Journals (Sweden)

    Maria do Céu Monteiro da Cruz

    2009-09-01

    Full Text Available O trabalho foi realizado com o objetivo de avaliar o estresse causado por deficiência hídrica para induzir o florescimento sobre a fluorescência da clorofila a em tangerineira 'Ponkan' e limeira ácida 'Tahiti'. As plantas foram enxertadas sobre o limoeiro 'Cravo', conduzidas em câmara de crescimento sob condições controladas. O estresse causado pela deficiência hídrica submetido à tangerineira 'Ponkan' e à limeira ácida 'Tahiti' reduziu a eficiência quântica potencial do fotossistema II (Fv/Fm. Após a irrigação, as plantas apresentaram valores dos parâmetros de fluorescência similares àqueles verificados antes do estresse submetido por deficiência hídrica.The research was carried out with the aim to evaluate the stress caused by water deficiency on a chlorophyll a fluorescence in 'Ponkan' mandarin and 'Tahiti' acid lime plants. The plants were grafted on Rangpur lime submitted to water stress in growth chamber under controlled conditions for induce the flowering. the stress caused by water deficiency submitted in plants of mandarin 'Ponkan' and 'Tahiti' lime decreased the potential quantum efficiency of photosystem II (Fv/Fm. After the irrigation the plants showed fluorescence parameters values similar to those prior to stress submitted by water deficiency.

  2. Fluorescence signals of core-shell quantum dots enhanced by single crystalline gold caps on silicon nanowires

    International Nuclear Information System (INIS)

    We use nanoscale (20-300 nm in diameter) single crystalline gold (Au)-caps on silicon nanowires (NWs) grown by the vapor-liquid-solid (VLS) growth mechanism to enhance the fluorescence photoluminescence (PL) signals of highly dilute core/shell CdSeTe/ZnS quantum dots (QDs) in aqueous solution (10-5 M). For NWs without Au-caps, as they appear, for example, after Au etching in aqua regia or buffered KI/I2-solution, essentially no fluorescence signal of the same diluted QDs could be observed. Fluorescence PL signals were measured using excitation with a laser wavelength of 633 nm. The signal enhancement by single crystalline, nanoscale Au-caps is discussed and interpreted based on finite element modeling (FEM).

  3. 双酚A对番茄和生菜幼苗叶绿素荧光参数的影响%Effects of Bisphenol A on Chlorophyll Fluorescence Parameters in Tomato and Lettuce

    Institute of Scientific and Technical Information of China (English)

    李曼; 王丽红; 周青

    2014-01-01

    利用叶绿素荧光测定技术,研究了BPA对番茄和生菜幼苗叶绿素荧光反应的影响。结果表明,1.5 mg·L-1和3.0 mg·L-1 BPA处理降低番茄和生菜初始荧光(F0),增加最大光化学量子产量(Fv/Fm)、实际光化学量子产量(ΦPSⅡ)、表观电子传递速率(ETR)、光化学猝灭(qP)和非光化学猝灭(qN);BPA作用解除后,各指标均有所恢复,即1.5 mg·L-1和3.0 mg·L-1 BPA可通过增加光能的吸收、改善PSⅡ系统、提高电子传递和光能转化效率、释放过量能量来增强光合作用,该作用随BPA解除而恢复。6.0 mg·L-1 BPA处理的番茄幼苗各荧光参数无显著变化,生菜幼苗F0和q N显著升高,可恢复到对照水平,表明6.0 mg·L-1 BPA已使生菜幼苗发生光抑制,BPA解除后可恢复至正常水平。除10 mg·L-1 BPA增加番茄qN外,10 mg·L-1和17.2 mg·L-1 BPA增加2种作物F0而抑制其他各荧光参数,恢复期时各荧光参数向对照组靠近,即高剂量BPA引起作物光抑制、PSⅡ中心受损、光能转化和电子传递效率降低。BPA解除后各项指标可恢复,但恢复程度随BPA处理剂量增加而降低。对比2种作物荧光参数变幅可知,BPA对生菜各荧光参数影响大于番茄,恢复期番茄幼苗各荧光参数恢复程度大于生菜。总之,BPA对2种作物叶绿素荧光反应的影响方式和影响效果上存在差异,且BPA作用解除后,叶绿素荧光反应有不同程度恢复,仅6.0 mg·L-1 BPA作用解除后能恢复至对照水平。%Bisphenol A(BPA), an endocrine disruptor, has showed obvious toxic effects on life system. However, little information is avail-able regarding the toxic effects of BPA on crops. A hydroponic experiment was carried out to investigate the effects of BPA on chlorophyll fluorescence in tomato(Solanum lycopersicum)and lettuce(Lactuca sativa)seedlings. Treatments with 1.5 mg·L-1 and 3.0 mg·L-1 BPA de-creased the F

  4. Acquisition and reconstruction of Raman and fluorescence signals for rat leg imaging

    Science.gov (United States)

    Demers, Jennifer-Lynn; Pogue, Brian; Leblond, Frederic; Esmonde-White, Francis; Okagbare, Paul; Morris, Michael

    2011-03-01

    Recovery of Raman or Fluorescence signatures from within thin tissues benefits from model-based estimation of where the signal came from, especially if the signal passes through layers in which the absorption or scattering signatures distort the signal. Estimation of the signal strength requires appropriate normalization or model-based recovery, but the key to achieving good results is a good model of light transport. While diffusion models are routinely used for optical tomography of tissue, there's some thought that more precise radiation transport modeling is required for accurate estimation. However, diffusion is often used for small animal imaging, because it's a practical approach, which doesn't require knowledge of the scatter phase function at each point in the tissue. The question asked in this study is, whether experimentally acquired data in small volumes such as a rodent leg can be accurately modeled and reconstructed using diffusion theory. This study uses leg geometries extracted from animal CT scans and liquid phantoms to study the diffusion approximations. The preliminary results show that under certain conditions the collected data follows the expected trend.

  5. A dual-color fluorescence-based platform to identify selective inhibitors of Akt signaling.

    Directory of Open Access Journals (Sweden)

    Aranzazú Rosado

    Full Text Available BACKGROUND: Inhibition of Akt signaling is considered one of the most promising therapeutic strategies for many cancers. However, rational target-orientated approaches to cell based drug screens for anti-cancer agents have historically been compromised by the notorious absence of suitable control cells. METHODOLOGY/PRINCIPAL FINDINGS: In order to address this fundamental problem, we have developed BaFiso, a live-cell screening platform to identify specific inhibitors of this pathway. BaFiso relies on the co-culture of isogenic cell lines that have been engineered to sustain interleukin-3 independent survival of the parental Ba/F3 cells, and that are individually tagged with different fluorescent proteins. Whilst in the first of these two lines cell survival in the absence of IL-3 is dependent on the expression of activated Akt, the cells expressing constitutively-activated Stat5 signaling display IL-3 independent growth and survival in an Akt-independent manner. Small molecules can then be screened in these lines to identify inhibitors that rescue IL-3 dependence. CONCLUSIONS/SIGNIFICANCE: BaFiso measures differential cell survival using multiparametric live cell imaging and permits selective inhibitors of Akt signaling to be identified. BaFiso is a platform technology suitable for the identification of small molecule inhibitors of IL-3 mediated survival signaling.

  6. 遮荫对四季草莓叶绿素荧光特性的影响%Effects of shading on the chlorophyll fluorescence parameters of Fragaria vesca cv.‘Selva’and‘Midlight’

    Institute of Scientific and Technical Information of China (English)

    罗华; 冯立娟; 李敏; 张连忠

    2012-01-01

    以四季草莓(Fragaria ananassa Duchesne)‘赛娃’(‘Selva’)和‘美德莱特,(‘Midlight')为试材,研究遮荫(透光率约30%)对四季草莓叶绿素荧光特性的影响.结果表明:遮荫处理显著提高了2个草莓品种叶片的叶面积及叶绿素a、b含量、叶绿素总量、叶绿素/类胡萝卜素值,类胡萝卜素含量变化不显著;遮荫降低了叶片Fo值,提高了Fv/Fm值与ΦPSII,表明遮荫后草莓叶片叶绿素分子捕获激发能的效率提高,减少了光照对PSII光化学反应中心的破坏,体现出叶片对光能利用率的提高和对遮荫环境的适应.遮荫提高了ETR,ETR日变化呈双峰曲线,峰值分别出现在10:00和14:00左右.遮荫提升了qP,降低了NPQ,NPQ的变化曲线与qP相反.四季草莓对弱光环境有一定的适应能力,中午时段(10:00-14:00)适度遮荫能减弱光照对四季草莓的光抑制,提高草莓对光能的利用能力.%Effects of shading (about 30% light transmittance) on the chlorophyll fluorescence parameters of seasonal strawberry cultivars were studied taking Fragaria vesca cv. 'Selva' and 'Midlight'as materials. The results showed that shading condition significantly increased the single leaf area and the content of chlorophyll a,b, a+b, chlorophyll/carotenoids ratio, and the content of carotenoids did not changed significantly. It decreased F。 and increased FVF/m and ΦsII. It demonstrated that it can improve the efficiency of chlorophyll molecules capturing excitation and reduce the destruction of light on PSII photochemical reaction center. So it showed the improvement of increasing utilization ratio of light energy and adaption to shade environment. Shading increased ETR, and the diurnal changes of ETR showed a two-peak curve. Peaks emerged at 10:00 and 14:00. Shading increased qP, decreased NPQ. Its curve was opposed to qP. Seasonal strawberry had certain ability to adapt to low light environment. Appropriate shading at noon time (10:00 -14

  7. Effects of drought stress on chlorophyll fluorescence parameters of two fast-growing tree species%干旱胁迫对2种速生树种叶绿素荧光特性的影响

    Institute of Scientific and Technical Information of China (English)

    白晶晶; 吴俊文; 李吉跃; 何茜; 邱权; 潘昕

    2015-01-01

    Objective] A comparison of drought resistance was made between two fast-growing species in South China, Eucalyptus urophylla ×E.grandis (EE for abbr.) and bamboo willow (BW for abbr.).[Method]Effective quantum yield of PSⅡ photochemistry ( Yield ) , apparent electron transport rate ( ETR) , the photochemical quenching ( qP ) , the non-photochemical quenching ( qN) , minimal fluores-cence(F0), maximal fluorescence(Fm), potential photochemical efficiency of PSⅡ(Fv/Fm) in EE and BW were tested by OS5P pulse modulated chlorophyll fluorometer under drought stress .[Result and con-clusion] Yield, ETR, qP, Fm and Fv/Fm all declined during the drought .At day 24 after treatment, ETR declined by 48.02% and 25.12% EE and BW , respectively.qN and F0 in the 2 species in-creased.qN in BW rose by 217.59%, which was significantly higher than that in EE (146.40%, P<0.05).The relative increment in F0 in BW (49.11%) was smaller than that in EE (92.03%) at the end of the drought treatment .Correlation analyses were made concerning chlorophyll fluorescence charac-teristics and soil water content .In both species , ETR showed a significant positive correlation with soil water content ( P<0.01 ) .F0 in EE showed a significant negative correlation with soil water content (P<0.01).Fm and Fv/Fm of BB and soil water content showed a significant positive correlation (P<0.01).These results indicate that correlations existe among chlorophyll fluorescence characteristics in two species under drought.BW has greater drought resistance than EE as revealed by chlorophyll fluo-rescence characteristics.%目的对华南地区2个速生树种尾巨桉Eucalyptus urophylla × E.grandis和竹柳( bamboo willow )的抗旱性进行比较.方法采用干旱胁迫处理,利用脉冲调制式叶绿素荧光仪( OS5 P-美国)对2树种叶绿素荧光参数进行测定.结果和结论在干旱胁迫条件下,实际光量子产量( Yield)、表观光合电子传递速率( ETR)、

  8. Using a biochemical C4 photosynthesis model and combined gas exchange and chlorophyll fluorescence measurements to estimate bundle-sheath conductance of maize leaves differing in age and nitrogen content.

    Science.gov (United States)

    Yin, Xinyou; Sun, Zhouping; Struik, Paul C; Van der Putten, Peter E L; Van Ieperen, Wim; Harbinson, Jeremy

    2011-12-01

    Bundle-sheath conductance (g(bs) ) affects CO(2) leakiness, and, therefore, the efficiency of the CO(2) -concentrating mechanism (CCM) in C(4) photosynthesis. Whether and how g(bs) varies with leaf age and nitrogen status is virtually unknown. We used a C(4) -photosynthesis model to estimate g(bs) , based on combined measurements of gas exchange and chlorophyll fluorescence on fully expanded leaves of three different ages of maize (Zea mays L.) plants grown under two contrasting nitrogen levels. Nitrogen was replenished weekly to maintain leaf nitrogen content (LNC) at a similar level across the three leaf ages. The estimated g(bs) values on leaf-area basis ranged from 1.4 to 10.3 mmol m(-2) s(-1) and were affected more by LNC than by leaf age, although g(bs) tended to decrease as leaves became older. When converted to resistance (r(bs) = 1/g(bs)), r(bs) decreased monotonically with LNC. The correlation was presumably associated with nitrogen effects on leaf anatomy such as on wall thickness of bundle-sheath cells. Despite higher g(bs), meaning less efficient CCM, the calculated loss due to photorespiration was still low for high-nitrogen leaves. Under the condition of ambient CO(2) and saturating irradiance, photorespiratory loss accounted for 3-5% of fixed carbon for the high-nitrogen, versus 1-2% for the low-nitrogen, leaves. PMID:21883288

  9. 酸雨对全生育时期水稻叶绿素荧光的影响%Effects of acid rain on the chlorophyll fluorescence reaction in rice at the whole growth stages

    Institute of Scientific and Technical Information of China (English)

    王雯; 李曼; 王丽红; 周青

    2014-01-01

    Acid rain is one of the global environmental issues. China has become the third largest acid rain region behind Western Europe and North America. Photosynthesis is the physiological basis of biomass and yield formation of plants, and chlorophyll fluorescence is commonly used for evaluating the damage of stress to photosynthesis of plants. Previous studies showed that acid rain influences the chlorophyll fluorescence of plants. However, the stress resistance of plants varies with the growth stage of plants. In the present work, the effects of acid rain on chlorophyll fluorescence of rice (Oryza sativa) at the whole growth stages (from seedling stage, tillering stage, booting stage and filling stage) were investigated, and none relevant reports have been published so far. Rice (from seedling stage to filling stage) were continuously treated with simulated acid rain (pH value of acid rain were 4.5, 3.5, 2.5) or control rain (sprayed every three days). The control leaves and acid rain-treated leaves of rice were sampled at seedling stage, tillering stage, booting stage and filling stage, respectively, to measure the chlorophyll fluorescence parameters with an in situ nondestructive testing technology (pulse modulation Chlorophyll Fluorometer PAM-210, Heinz Walz GmbH, Germany). The results showed that when rice was treated with acid rain at pH 4.5, initial fluorescence (Fo) at seedling stage and booting stage were significantly increased 7.69%and 8.84%, non-photochemical quenching coefficient (qN) at seedling stage, tillering stage and booting stage were significantly increased 8.64%, 4.86%and 6.09%, maximal chlorophyll fluorescence (Fv/Fm), electron transport rate of PSII (ETR), effective quantum yield of photochemical energy conversion of PSII (ΦPSII), photochemical quenching coefficient (qP) at seedling stage and booting stage were significantly decreased, the decreased degrees were 3.01%and 6.88%(Fv/Fm), 8.40%and 10.24% (ETR), 8.39% and 12.23% (ΦPSII), 3.79% and

  10. Thousand-fold fluorescent signal amplification for mHealth diagnostics.

    Science.gov (United States)

    Balsam, Joshua; Rasooly, Reuven; Bruck, Hugh Alan; Rasooly, Avraham

    2014-01-15

    The low sensitivity of Mobile Health (mHealth) optical detectors, such as those found on mobile phones, is a limiting factor for many mHealth clinical applications. To improve sensitivity, we have combined two approaches for optical signal amplification: (1) a computational approach based on an image stacking algorithm to decrease the image noise and enhance weak signals, and (2) an optical signal amplifier utilizing a capillary tube array. These approaches were used in a detection system which includes multi-wavelength LEDs capable of exciting many fluorophores in multiple wavelengths, a mobile phone or a webcam as a detector, and capillary tube array configured with 36 capillary tubes for signal enhancement. The capillary array enables a ~100× increase in signal sensitivity for fluorescein, reducing the limit of detection (LOD) for mobile phones and webcams from 1000 nM to 10nM. Computational image stacking enables another ~10× increase in signal sensitivity, further reducing the LOD for webcam from 10nM to 1 nM. To demonstrate the feasibility of the device for the detection of disease-related biomarkers, adenovirus DNA labeled with SYBR green or fluorescein was analyzed by both our capillary array and a commercial plate reader. The LOD for the capillary array was 5 ug/mL, and that of the plate reader was 1 ug/mL. Similar results were obtained using DNA stained with fluorescein. The combination of the two signal amplification approaches enables a ~1000× increase in LOD for the webcam platform. This brings it into the range of a conventional plate reader while using a smaller sample volume (10 ul) than the plate reader requires (100 ul). This suggests that such a device could be suitable for biosensing applications where up to 10 fold smaller sample sizes are needed. The simple optical configuration for mHealth described in this paper employing the combined capillary and image processing signal amplification is capable of measuring weak fluorescent signals

  11. Measurement of radiative lifetime in atomic samarium using simultaneous detection of laser-induced fluorescence and photoionization signals

    Indian Academy of Sciences (India)

    A C Sahoo; M L Shah; P K Mandal; A K Pulhani; G P Gupta; Vas Dev; B M Suri

    2014-02-01

    In this paper, we report the investigations of lifetime measurement of odd-parity energy level 19009.52 cm-1 of Sm I using simultaneous detection of laser-induced fluorescence and laserinduced photoionization signals employing pump–probe technique. To the best of our knowledge, this is for the first time that the results obtained using laser-induced fluorescence and photoionization techniques have been compared with each other. The obtained results match well with those reported in the literature.

  12. Fluorescence-enhancement with different ionic inputs in a cryptand-based multi-receptor signalling system

    Indian Academy of Sciences (India)

    Bamaprasad Bag; Parimal K Bharadwaj

    2005-03-01

    Two molecules of a laterally non-symmetric aza cryptand have been attached to 9,10-dimethylanthracene to obtain a multi-receptor fluorescent signalling system in the ``receptor-spacer-fluorophore- spacer-receptor” format. In the absence of a metal ion, weak fluorescence is observed upon excitation of the anthryl group owing to efficient photo-induced electron transfer (PET) of the lone pair of N attached to the anthryl group. However, when a metal salt is added, the lone pair is engaged, thus in blocking of the PET and leading to recovery of fluorescence to different extents depending upon the nature of the metal ion.

  13. Amplification of the Signal Intensity of Fluorescence-Based Fiber-Optic Biosensors Using a Fabry-Perot Resonator Structure

    Directory of Open Access Journals (Sweden)

    Meng-Chang Hsieh

    2015-02-01

    Full Text Available Fluorescent biosensors have been widely used in biomedical applications. To amplify the intensity of fluorescence signals, this study developed a novel structure for an evanescent wave fiber-optic biosensor by using a Fabry-Perot resonator structure. An excitation light was coupled into the optical fiber through a laser-drilled hole on the proximal end of the resonator. After entering the resonator, the excitation light was reflected back and forth inside the resonator, thereby amplifying the intensity of the light in the fiber. Subsequently, the light was used to excite the fluorescent molecules in the reactive region of the sensor. The experimental results showed that the biosensor signal was amplified eight-fold when the resonator reflector was formed using a 92% reflective coating. Furthermore, in a simulation, the biosensor signal could be amplified 20-fold by using a 99% reflector.

  14. NaCl胁迫对马齿苋离子吸收及荧光特性的影响%Effects of NaCl Stress on the Ion Distribution and Chlorophyll Fluorescence in Portulaca oleracea L.

    Institute of Scientific and Technical Information of China (English)

    丁海荣; 王茂文; 朱小梅; 刘冲; 邢锦城; 赵宝泉; 陈昌乾; 洪立洲

    2012-01-01

    以马齿苋为材料采用温室盆栽法,研究了NaCl胁迫处理对其生长发育、品质积累、离子分布和叶绿素荧光特性的影响.结果表明,马齿苋种子发芽率、幼苗的鲜质量和株高在25~50 mmol/L NaCl胁迫时比对照略有下降,但其随着NaCl浓度的继续增加均显著降低.0~75 mmol/L NaCl处理浓度可提高马齿苋幼苗维生素C含量.盐胁迫影响植物组织的离子分布,Na+浓度持续增加,K+、Ca2+和Mg2浓度下降.NaCl胁迫下,马齿苋幼苗叶片的初始荧光(Fo)、最大荧光(Fm)、PSⅡ潜在光化学效率(Fv/Fo)和PSⅡ实际光化学效率(ΦPSⅡ)均降低.但在0~50 mmol/LNaCl浓度下,各荧光参数与对照差异不显著.可见,NaCl胁迫下,马齿苋产生了光合作用的光抑制伤害.低浓度下,植株能够较多地将光能用于光化学反应,光抑制程度较低,保持了较高的净光合速率,最终明显减轻盐胁迫对植株生长的影响.%Pot experiments were carried out to study the effects of NaCl stress on the growth, quality, ion distribution and chlorophyll fluorescence in Portulaca oleracea L. Eight different concentrations of NaCl were applied ;0, 25,50,75,100,150,200,250 mmol/L. The results showed as follows;The germination rate,plant fresh weights and heights of seedlings had no difference with the control when the concentration of NaCl was 25 -50 mmol/L,but decreased when the NaCl concentration was above 50 mmol/L. When the concentration of NaCl was 0-75 mmol/L, the Vc content of Portulaca oleracea L. increased. Increased treatment of NaCl induces increased of Na + and decreased of K+ , Mg2+ and Ca2+. Minimal fluorescence (Fo) ,maximum fluorescence (Fm) ,PS II potential fluorescence efficiency (Fv/Fo) and PS H actual fluorescence efficiency ( ΦPSⅡ ) all decreased when stressed by NaCl. And at low concentrations NaCl (0-50 mmol/L) stress,the fluorescence parameters changed slightly. So Portulaca oleracea L. was injured by photo

  15. Effects of Nitrogen Rate on the Characteristics of Photosynthesis and Chlorophyll Fluorescence in Potato (Solanum Tuberosum L.)%氮肥水平对马铃薯光合及叶绿素荧光特性的影响

    Institute of Scientific and Technical Information of China (English)

    郑顺林; 杨世民; 李世林; 袁继超

    2013-01-01

    以3个品种为材料,采用随机区组设计,在田间试验条件下,研究了施氮水平对春、秋马铃薯Solanum Tuberosum L.光合和叶绿素荧光特性的影响,以期为合理氮肥运筹,提高马铃薯光能利用提供理论依据.结果表明:①增施氮肥因提高了功能叶的叶绿素质量分数而显著影响春、秋马铃薯的净光合速率及其对光照强度和CO2体积分数的响应,但影响的程度和趋势在春、秋马铃薯之间有一定差异.在试验的处理范围内,春马铃薯功能叶的最大净光合速率(Am)、表观量子效率(ψ)随施氮水平的增加而提高,而秋马铃薯的Am和ψ则随氮肥用量的增加先增后减,春薯光合作用的光饱和点和补偿点均大于秋薯,表明马铃薯光合作用的氮肥效应受栽培季节的影响;②氮肥水平对马铃薯功能叶片叶绿素的荧光特性也有一定影响,适量的氮肥可以提高最大光化学效率(Fv/Fm)、实际光化学效率(ΦpsⅡ)和电子传递速率(ETR),降低光化学猝灭系数(qP)和非光化学猝灭系数(qN),从而增加PsⅡ天线色素对光能的捕获效率,降低光能的热耗散,提高PsⅡ的光化学效率;③不同马铃薯品种的光合与叶绿素荧光特性及其对氮肥的响应存在一定差异,在秋播和中高氮水平下,川芋117的Am、羧化效率(CE)、Fv/Fm、ΦpsⅡ、ETR和qP等光合和叶绿素荧光参数均高于青薯2号.%Two field experiments were conducted with three potato varieties in spring and autumn in Ya'an, Sichuan province to study the effects of nitrogen rate on the characteristics of photosynthesis and chloro-phyll fluorescence of the plants. The main results were as follows: 1) The increase in nitrogen rate increased the chlorophyll content of the functional leaves and thus significantly improved the net photosyn-thetic rate (Pn) and its response to light intensity and CO2 concentration of both spring and autumn potato. However, some differences between

  16. Investigation of signal-to-noise ratio in frequency-domain multiphoton fluorescence lifetime imaging microscopy.

    Science.gov (United States)

    Zhang, Yide; Khan, Aamir A; Vigil, Genevieve D; Howard, Scott S

    2016-07-01

    Multiphoton microscopy (MPM) combined with fluorescence lifetime imaging microscopy (FLIM) has enabled three-dimensional quantitative molecular microscopy in vivo. The signal-to-noise ratio (SNR), and thus the imaging rate of MPM-FLIM, which is fundamentally limited by the shot noise and fluorescence saturation, has not been quantitatively studied yet. In this paper, we investigate the SNR performance of the frequency-domain (FD) MPM-FLIM with two figures of merit: the photon economy in the limit of shot noise, and the normalized SNR in the limit of saturation. The theoretical results and Monte Carlo simulations find that two-photon FD-FLIM requires 50% fewer photons to achieve the same SNR as conventional one-photon FLIM. We also analytically show that the MPM-FD-FLIM can exploit the DC and higher harmonic components generated by nonlinear optical mixing of the excitation light to improve SNR, reducing the required number of photons by an additional 50%. Finally, the effect of fluorophore saturation on the experimental SNR performance is discussed. PMID:27409702

  17. Effects of Cu2+ on the Growth and Chlorophyll Fluorescence of Two Species of Marine Microalgae%Cu2+对两种海洋微藻生长和叶绿素荧光特性的影响

    Institute of Scientific and Technical Information of China (English)

    姜恒; 吴斌; 阎冰; 吴志强; 邢永泽

    2013-01-01

    The changes of the fluorescence parameters of Dicrateria zhanjiangensis and Isochrysis galbana MACC/H59 exposed to Cu2+ were investigated by means of the chlorophyll fluorescence technology(Water-PAM) ,and the growth of these two species of marine microal-gae was observed. The results showed that all fluorescence parameters ( Fv/Fm ,Fv/F0,Yield and ETR) of Dicrateria zhanjiangensis and Isochrysis galbana MACC/H59 decreased under Cu2+ stress. The growth of cell density for Dicrateria zhanjiangensis and Isochrysis galbana MACC/H59 decreased under Cu2+ stress,and it can be expressed as Dicrateria zhanjiangensis > Isochrysis galbana MACC/H59 in the 24h while it can be expressed as Isochrysis galbana MACC/H59> Dicrateria zhanjiangensis during 48h to 96h. The toxicity of Dicrateria zhanjiangensis and Isochrysis galbana MACC/H59 increased with the increase of exposure time.%运用水样叶绿素荧光仪(WATER-PAM)研究Cu2+胁迫下,湛江叉鞭金藻(Dicrateria zhanjiangensis)和球等鞭金藻3011(Isochrysis galbana MACC/H59)叶绿素荧光特性的变化,同时监测微藻的生长情况.结果就叶绿素荧光参数而言,湛江叉鞭金藻和球等鞭金藻3011的叶绿素荧光参数Fv/Fm,Fv/F0,Yield和ETR均随着Cu2+浓度的增大而明显降低;就生长情况而言,随着Cu2+浓度的增大,两种海洋微藻细胞密度的增长明显变缓.在24 h时Cu2+对湛江叉鞭金藻的毒性大于球等鞭金藻3011,48~96 h时Cu2+对球等鞭金藻3011的毒性大于湛江叉鞭金藻,Cu2+的毒性随着胁迫时间的延长而逐步增大.

  18. Identification of a functional nuclear export signal in the green fluorescent protein asFP499

    International Nuclear Information System (INIS)

    The green fluorescent protein (GFP) asFP499 from Anemonia sulcata is a distant homologue of the GFP from Aequorea victoria. We cloned the asFP499 gene into a mammalian expression vector and showed that this protein was expressed in the human lymphoblast cell line Ramos RA1 and in the embryonic kidney 293T cell line (HEK 293T). In HEK 293T cells, asFP499 was localized mainly in the cytoplasm, suggesting that the protein was excluded from the nucleus. We identified 194LRMEKLNI201 as a candidate nuclear export signal in asFP499 and mutated the isoleucine at position 201 to an alanine. Unlike the wildtype form, the mutant protein was distributed throughout the cytoplasm and nucleus. This is First report of a GFP that contains a functional NES

  19. A signal sequence is sufficient for green fluorescent protein to be routed to regulated secretory granules.

    Science.gov (United States)

    El Meskini, R; Jin, L; Marx, R; Bruzzaniti, A; Lee, J; Emeson, R; Mains, R

    2001-02-01

    To investigate trafficking in neuroendocrine cells, green fluorescent protein (GFP) tags were fused to various portions of the preproneuropeptide Y (NPY) precursor. Two neuroendocrine cell lines, AtT-20 corticotrope tumor cells and PC-12 pheochromocytoma cells, along with primary anterior pituitary cells, were examined. Expression of chimeric constructs did not disrupt trafficking or regulated secretion of endogenous ACTH and prohormone convertase 1 in AtT-20 cells. Western blot and immunocytochemical analyses demonstrated that the chimeric constructs remained intact, as long as the Lys-Arg cleavage site within preproNPY was deleted. GFP was stored in, and released from, regulated granules in cells expressing half of the NPY precursor fused to GFP, and also in cells in which only the signal sequence of preproNPY was fused to GFP. Thus, in neuroendocrine cells, entering the lumen of the secretory pathway is sufficient to target GFP to regulated secretory granules. PMID:11159860

  20. Chlorophyll and starch assays

    OpenAIRE

    sprotocols

    2015-01-01

    Chlorophyll, starch, and sugar contents are good indicators of growth vigor in plants. To measure the chlorophyll content, we used a modified protocol (1,2). The starch content was determined using iodine staining (3) and enzymatic reactions (4-6).

  1. EFFECTS OF HEAVY METAL EXPOSURE ON THE CELL DENSITY AND CHLOROPHYLL FLUORESCENCE OF PYRAMIDOMONAS SP.%重金属胁迫对塔胞藻细胞密度及叶绿素荧光特性的影响

    Institute of Scientific and Technical Information of China (English)

    王帅; 梁英

    2011-01-01

    The modulate chlorophyll fluorescence kinetics of Pyramidomonas sp. Under dif ferent heavy metal concentrations (Cu2+ , Zn2+ , Cd2+) and different time ( 24h, 48h, 72h, and 96h) were investigated with Water-PAM chlorophyll fluorometer. The main parameters determined in the present study included the maximal photochemical efficiency of PSII (Fv/ Fm), the potential activity of PSII (Fv/Fo), the actual photochemical efficiency of PSII in the light (Yield), the relative electron transport rate (rETR), the photochemical quenching (qP) and the non-photochemical quenching (NPQ). The results showed that the fluores cence parameters Fv/Fm. Fv/F0, Yieldt rETR? And qP of Pyramidomonas sp. All decreased under heavy metal (Cu2+ , Zn2+ , Cd2+ ) exposure. The changed degree of the above parame ters increased with the increase of heavy metal concentration and increasing exposure time. NPQ changed erratically with the increasing exposure time under heavy metal exposure. The cell density and relative chlorophyll content were also decreased under heavy metal exposure. The Ecso(the effective concentration causing a 50% inhibition) values indicated that the tox icity results can be expressed as Cu2+> Cd2+>Zn2+.%采用调制式叶绿素荧光仪测定了重金属(Cu2+、Zn2+、Cd2+)胁迫(24h、48h、72h和96h)对塔胞藻叶绿素荧光特性的影响.测定的主要参数有:PSII的原初光能转化效率(Fv/Fm)、PSII的潜在活性(Fv/Fo)、PSII的实际光能转化效率(Yield)、相对表现电子传递效率(rETR)、光化学淬灭(qP)和非光化学淬灭(NPQ).研究结果表明,重金属离子(Cu2+、Zn2+、Cd2+)胁迫下塔胞藻的叶绿素荧光参数Fv/Fm、Fv/Fo、Yield、rETR和qP均明显降低,并且随着重金属离子浓度的增加,胁迫时间的延长,下降幅度逐步增大;NPQ变化不规律;细胞密度和叶绿素相对含量也显著降低.对3种重金属离子的半抑制浓度(EC50)的计算结果表明,3种重金属毒性大小顺序为Cu2+> Cd2+

  2. 不同施肥处理对核桃叶片光合作用和叶绿素荧光特性的影响%Effects of different fertilization treatments on photosynthesis, chlorophyll fluorescence characteristics of walnuts

    Institute of Scientific and Technical Information of China (English)

    杜研; 杨文忠; 孙林琦; 钱立龙

    2015-01-01

    To reveal the response mechanism of the photosynthetic characteristics,walnuts (cv. Xinwen185)were treated to compare of chlorophyll contents,photosynthesis and chlorophyll fluorescence change under four different fertilization,organic fertilizer combined with chemical fertilizer(NPKM),or-ganic fertilizer (M),chemical fertilizer (NPK),farmers experience fertilization (CK).The results showed that chlorophyll content of walnut treated with NPKM was 3.64%,5.13% and 13.39% higher than that of M,NPK and CK.NPKM,M and NPK treatments improved PSII maximal photochemical efficiency (F v/Fm)and PSII potential liveness (F v/F 0 ),response to fertilizer effect was as:NPKM>M>NPK>CK.The diurnal variation curves of P n of presented the ‘up-down-up-down’double-apex curves,and had a phenom-enon of photosynthetic ‘noon breaking’,the diurnal variation curves of Gs were same as P n ,fertilization effect was as:NPKM>M>NPK>CK.%为揭示核桃的光合作用的响应机制,以‘新温185号’核桃为试验品种,比较其在有机肥与化肥配施(NPKM)、单施有机肥(M)、单施化肥(NPK)、农民经验施肥(CK)4种施肥处理下叶片的叶绿素含量、光合特性、叶绿素荧光特性的变化.结果表明:NPKM 处理下核桃叶片的的叶绿素含量分别比 M 处理、NPK 处理、CK 处理提高了3.64%、5.13%、13.39%;与 CK 处理相比,NPKM 处理、M 处理、NPK 处理均能提高核桃叶片的 PSII 原初光能转化效率(Fv/Fm )和 PSII 反应中心潜在活性(Fv/F0),肥效响应为:NPKM 处理>M 处理>NPK 处理>CK 处理;各处理下核桃叶片的净光合速率日变化均呈“升-降-升-降”的双峰曲线,具有明显的“午休”现象,气孔导度值的日变化与净光合速率相似,光合施肥效应表现为:NPKM 处理>M 处理>NPK 处理>CK 处理.

  3. Effects of Acid Rain Stress on Antioxidant Enzyme Activity and Chlorophyll Fluorescence in Leaves of Gazania Hybrids%酸雨对勋章菊保护酶活性及叶绿素荧光参数的影响

    Institute of Scientific and Technical Information of China (English)

    侯维; 潘远智

    2013-01-01

    In this paper,pot experiments were conducted to study the effect of simulated acid rain that included four different pH values (5.6,4.5,3.5,2.5) on the membrane permeability,malondialdehyde (MDA) content and antioxidant enzyme activity,chlorophyll (Chl) content,and chlorophyll fluorescence in of leaves Gazania Hybrids.The membrane permeability and MDA content increased significantly after acid rain stress and with an extremely significant correlation between them.The dismutase (SOD),catalase (CAT) and peroxidase (POD) activities were showed a single-peak curve which was firstly increased and then decreased,and the maximum activity of SOD,CAT and POD were observed at pH4.5.Chl a,Chl b,total chlorophyll content,Chl a/b,the PS Ⅱ photochemical efficiency (Fv/ Fm) and the PS Ⅱ potential activity (Fv/Fo),actual PS Ⅱ photochemical quantum yield (ΦpsⅡ) and qP decreased accordingly with the decreasing of pH value,while qN increased.The study showed that G.Hybrids has strong resistance to acid rain stress and the visible damage threshold was less than pH 3.5.Therefore,G.Hybrids can be considered as one of the landscaping and vegetation constructing plants in the acid rain-hit areas.%采用盆栽方法,以不同pH值(5.6、4.5、3.5、2.5)的模拟酸雨胁迫试验,探讨其对勋章菊(Gazania Hybrids)叶片质膜透性、MDA含量、保护酶活性、叶绿素含量及叶绿素荧光参数的影响.结果表明,随pH值的降低,勋章菊叶片质膜透性和MDA含量呈逐渐升高的趋势,且二者呈显著正相关;SOD、CAT和POD活性呈先升高后下降的单峰曲线变化,其中SOD、CAT和POD活性最大值均出现在pH4.5处理;叶绿素a、叶绿素b、叶绿素a+b的含量、叶绿素a/b、PSⅡ最大光化学效率(Fv/Fm)、PSⅡ的潜在活性(Fv/Fo)、PSⅡ实际光化学量子产量(Φps.Ⅱ)、光化学淬灭系数(qP)均随pH值的降低而下降,非光化学淬灭系数(qN)随pH值的降低而升高.模拟酸雨对勋章菊叶片

  4. Chlorophyll Degradation in Horticultural Crops

    OpenAIRE

    Kaewsuksaeng, Samak

    2011-01-01

    One of the symptoms of senescence in harvested horticultural crops is the loss of greenness that comes with the degradation of chlorophyll. With senescence, the chlorophyll-degrading enzyme activities such as chlorophyllase, Mg-dechelatase or Mg-dechelation activity, a new chlorophyll-degrading enzyme, pheophytinase, pheophorbidase and chlorophyll-degrading peroxidase, which are involved in chlorophyll degradation, affected greatly in stored horticultural crops. The chlorophyll derivatives, e...

  5. Small molecule aptamer assays based on fluorescence anisotropy signal-enhancer oligonucleotides.

    Science.gov (United States)

    Perrier, Sandrine; Bouilloud, Prisca; De Oliveira Coelho, Gisella; Henry, Mickael; Peyrin, Eric

    2016-08-15

    Herein, we design novel fluorescence anisotropy (FA) aptamer sensing platforms dedicated to small molecule detection. The assay strategy relied on enhanced fluctuations of segmental motion dynamics of the aptamer tracer mediated by an unlabelled, partially complementary oligonucleotide. The signal-enhancer oligonucleotide (SEO) essentially served as a free probe fraction revealer. By targeting specific regions of the signalling functional nucleic acid, the SEO binding to the unbound aptamer triggered perturbations of both the internal DNA flexibility and the localized dye environment upon the free probe to duplex structure transition. This potentiating effect determined increased FA variations between the duplex and target bound states of the aptameric probe. FA assay responses were obtained with both pre-structured (adenosine) and unstructured (tyrosinamide) aptamers and with dyes of different photochemical properties (fluorescein and texas red). The multiplexed analysis ability was further demonstrated through the simultaneous multicolour detection of the two small targets. The FA method appears to be especially simple, sensitive and widely applicable. PMID:27085946

  6. 铅对山梨和山荆子光合作用和叶绿素荧光特性的影响%Influence of Pb on Photosynthesis and Chlorophyll Fluorescence Characteristics in Pyrus ussuriensis and Malus baccata

    Institute of Scientific and Technical Information of China (English)

    李亚藏; 梁彦兰; 王庆成

    2012-01-01

    以北方阔叶树种山梨(Pyrus ussuriensis)和山荆子(Malus baccata)1年生苗木为材料,采用土壤和风化砂混合物作为盆栽基质,设置0(CK)、100、500、1000、2000 mg·kg-15种土壤铅浓度,研究了土壤铅胁迫对苗木叶片光合作用和叶绿素荧光特性的影响.结果表明:随着土壤铅胁迫浓度增加,山梨的净光合速率(Pn)持续下降,气孔导度(Gs)先升后降、胞间二氧化碳浓度(Ci)和蒸腾速率(Tr)持续升高;同时山荆子的Pn和Gs先升后降,Ci在100 mg·kg-1出现谷值,随后逐渐升高,Tr持续升高;随土壤铅处理浓度的增加,山梨的Fv/Fm、Fv/Fo和qN逐渐增加,山荆子逐渐下降,qP和(Φ)pSⅡ二者均表现为先升后降.研究发现,铅污染胁迫导致的Pn的下降是由非气孔限制因素所致;铅污染对山梨叶绿素荧光特性起促进作用,对山荆子影响不显著(p<0.05);综合各项参数山梨对土壤铅的耐性>山荆子.%One-year-old seedlings of two broadleaved trees occurring in Northern China, Pyrus ussuriensis and Malus baccata were potted in the mixed substrates of soil and weathered sand, in which different concentrations of lead salt (0, 100, 500, 1 000, and 2 000 mg · kg-1) were applied to examine the influence of Pb on the photosynthesis and chlorophyll fluorescence characteristics in the leaves of the seedlings tested. The results showed that with the increase of Pb concentration, Pn of P. ussuriensis declines continuously; Gs first increased and then decreased; C, and Tr increased continuously; Fv/Fm, Fv/Fo and qN gradually increased. For M. baccata, Pn and Gs first increased and then decreased; C, appeared minimum value in the Pb concentration of 100 mg · kg~' and then gradually increased; Tr increased continuously; Fv/Fm, Fv/ Fo and qN gradually declined. Values of qP and Φpsh in the leaves of two species showed first increased and then decreased. The decline of Pn in the leaves under lead stress was resulted from non

  7. THE INTERACTION EFFECTS OF DIFFERENT CD2+ CONCENTRATIONS AND TEMPERATURE ON THE GROWTH AND CHLOROPHYLL FLUORESCENCE OF 3 MICROALGAL STRAINS%Cd2+浓度、温度及交互作用对3株微藻生长及叶绿素荧光特性的影响

    Institute of Scientific and Technical Information of China (English)

    王帅; 梁英

    2012-01-01

    Chlorophyll fluorescence measurement has several good characteristics, such as very quick, extremely sensitive, non-invasive and non-destructive, thus becomes a widely used technique for the investigation of mechanisms of photosynthesis and to study the effects of various environmental conditions (temperature, salinity, heavy metal stress, nutrient deficiency) on the microalgal photosynthetic reactions, particularly for stress physiology of mi-croalgae. In this study, the interaction effects of different Cd2+ concentrations (Chlorella sp. S 0, 20, 40fimol/L:Nannochloris oculata -. 0, 10, 30fimol/L: Dunaliella salina : 0, 70, 140fimol/L) and different temperature (Chlorella sp. And N. Oculata: 20, 25, 30℃ : D. Salina : 15, 25, 35℃) on the chlorophyll fluorescence parameters (Fv/Fm, Yield, qP and NPQ), relative chlorophyll content and cell density of 3 microalgal strains were reported. The above fluorescence parameters including the ratio of variable to maximal chlorophyll fluorescence (Fv/Fm), which has been shown to be a sensitive indicator of photosynthetic performance and photoinhibition, the actual photochemical efficiency of PSII in the light (ΦPSII), the photochemical quenching (qP) and the non-photochemical quenching (NPQ). The 3 microalgal strains used in the experiment were obtained from the Microalgae Culture Center (MACC), Ocean University of China. Cultures were grown in sterilized seawater enriched with f/2 medium. The salinity was adjusted to 28 by using distilled water, and the light intensity was l00μmol o m-2 o s-1. The results showed that the chlorophyll fluorescence parameters, relative chlorophyll contents and cell densities all decreased obviously in the 3 microalgal strains with the increasing heavy metal (Cd2+ ) concentrations, with the exception of Fv/Fm in N. Oculata, where there was no significant difference between the control and the l0μmol/L Cd2+ concentration treatment. This was primarily due to the stimulation algal growth by

  8. 间作遮荫对花生光合作用及叶绿素荧光特性的影响%Effect of Shading on Photosynthesis and Chlorophyll Fluorescence Characteristic of Peanut under Different Inter-row Space in Cassava-peanut Intercropping

    Institute of Scientific and Technical Information of China (English)

    唐秀梅; 唐荣华; 钟瑞春; 揭红科; 刘超; 王泽平; 韩柱强; 蒋菁; 贺梁琼; 李忠

    2011-01-01

    以花生单作为对照,设置30、35、40、45、50 cm 5个木薯花生间作行距,播种90d后测定花生叶片的净光合速率、叶绿素含量及叶绿素荧光参数.结果表明,与单作对照相比,间作花生的光合速率(Pn)、叶绿素含量(Chl a+b)、初始荧光(Fo)、光化学猝灭系数(qP)降低;最大荧光(Fm)、可变荧光(Fv)、最大光化学效率(Fv/ Fm)、潜在光化学活性(Fv/Fo)、非光化学淬灭系数(qN)升高;且窄行距(30~35 cm)处理的Pn、Fv、Fv/Fm、Fv/Fo、表观光合电子传递速率(ETR)、实际光化学量子效率(Yield)高于宽行距(45~50cm)处理.间作遮荫使花生功能叶片的光合速率和叶绿素含量降低,叶绿素荧光参数的一系列变化是花生对间作遮荫的适应性反应.%The net photosynthetic rate, chlorophyll content and chlorophyll fluorescence characteristic of peanut (Arachis hypogaea L. ) were determined under different inter-row space of cassava/peanut intercropping (30, 35, 40, 45, 50 cm) and monocropping in the field after 90 d of sowing. The result showed that the net photosynthetic rate and chlorophyll ( Chi a + b) content, initial fluorescence ( Fo) , photochemical quenching (qP) in leaves of peanut intercropped with cassava decreased. However, the maximum fluorescence (Fm) , variable fluorescence (Fv) , maximum photochemical efficiency (Fv/Fm), potential activity of photosystem II {Fv/Fo, non-photochemical quenching (qN) of intercropped peanut increased. Moreover, Pn, Fv, Fv/Fm , Fv/ Fo, apparent electron transport rates (£77?) and effective quantum yield of photosystem II ( Yield) of peanut intercropped under 30 - 35 cm inter-row treatment were more than those under 40-45 cm row space. In conclusion, the shading of intercropping decreased net photosynthetic rate and chlorophyll content of peanut in leaves, and these changes of chlorophyll fluorescence characteristic showed that peanut had flexibility to shading stress under intercropping.

  9. Dopamine Receptor Signaling in MIN6 β-Cells Revealed by Fluorescence Fluctuation Spectroscopy.

    Science.gov (United States)

    Caldwell, Brittany; Ustione, Alessandro; Piston, David W

    2016-08-01

    Insulin secretion defects are central to the development of type II diabetes mellitus. Glucose stimulation of insulin secretion has been extensively studied, but its regulation by other stimuli such as incretins and neurotransmitters is not as well understood. We investigated the mechanisms underlying the inhibition of insulin secretion by dopamine, which is synthesized in pancreatic β-cells from circulating L-dopa. Previous research has shown that this inhibition is mediated primarily by activation of the dopamine receptor D3 subtype (DRD3), even though both DRD2 and DRD3 are expressed in β-cells. To understand this dichotomy, we investigated the dynamic interactions between the dopamine receptor subtypes and their G-proteins using two-color fluorescence fluctuation spectroscopy (FFS) of mouse MIN6 β-cells. We show that proper membrane localization of exogenous G-proteins depends on both the Gβ and Gγ subunits being overexpressed in the cell. Triple transfections of the dopamine receptor subtype and Gβ and Gγ subunits, each labeled with a different-colored fluorescent protein (FP), yielded plasma membrane expression of all three FPs and permitted an FFS evaluation of interactions between the dopamine receptors and the Gβγ complex. Upon dopamine stimulation, we measured a significant decrease in interactions between DRD3 and the Gβγ complex, which is consistent with receptor activation. In contrast, dopamine stimulation did not cause significant changes in the interactions between DRD2 and the Gβγ complex. These results demonstrate that two-color FFS is a powerful tool for measuring dynamic protein interactions in living cells, and show that preferential DRD3 signaling in β-cells occurs at the level of G-protein release. PMID:27508444

  10. Chlorophyll Fluorescence Characteristic of Ten Bamboo Species of Bambusa in Coastal Sandy Area%滨海沙地簕竹属10个竹种叶绿素荧光特性研究

    Institute of Scientific and Technical Information of China (English)

    涂志华; 潘瑞; 洪雪沿; 荣俊冬; 陈礼光; 郑郁善

    2012-01-01

    通过利用叶绿素荧光测定技术测定滨海沙地簕竹属10个竹种的叶绿素荧光参数试验研究,结果表明:(1)鼓节竹、观音竹、凤尾竹的初始荧光(Fo)、可变荧光(Fv)、最大荧光(Fm)值较高于其它竹种;(2)河边竹、观音竹、青皮竹、青竿竹的PSⅡ最大光化学效率(Fv/Fm)、PSⅡ的潜在活性(Fv/Fo)、PS Ⅱ实际光化学效率(QY)、PSⅡ电子传递量子产率(ΦPSⅡ)等值均高于其它竹种;(3)河边竹、花孝顺竹、破蔑黄竹、青竿竹的光化学猝灭系数(Qp)相对较高;(4)河边竹、青皮竹、青竿竹、鼓节竹的非光化学猝灭系数(NPQ)值相对较低.综上可以看出簕竹属中河边竹、观音竹、青皮竹、青竿竹具有较好的光合生理功能,可作为沿海沙地竹子引种的优选竹种.%Chlorophyll fluorescence parameters of ten bamboo species of Bambusa in the coastal sandy area, i. e. B. tuldoides Munro, B. multiplex cv. Fernleaf, B. mutiplex var. riviereorum R. Maire, B. tuldoides cv. Swolleninternode,B. contracta,B. textilis,B. multiplex var. strigosa, B. ventricosa, B. multiplex cv. alphonse-karr and B. vulgaris cv. vittata, were measured. The results showed that the minimal fluorescence ( Fo) , the variable fluorescence (Fv) , the maximal fluorescence (Fm)of B. tuldoides cv. Swolleninternode, B. mutiplex var. riviereorum R. Maire and B. multiplex cv. Fernleaf were higher than the other species. The PS II maximal photochemical efficiency ( Fv/Fm) , the PSⅡpotential photochemical efficiency ( Fv/ Fo) , the PS II actual photochemical efficiency ( QY ) , and the PS Ⅱ quantum yield of linear electron (ΦPS Ⅱ ) of B. multiplex var. strigosa, B. mutiplex var. riviereorum R. Maire, B. textilis McClure, B. tuldoides Munro were higher than the other species. The photochemical quenching coefficient ( Qp ) of B. multiplex var. strigosa , B. multiplex cv. Alphonse-Karr, B. contracta and B. tuldoides Munro were higher than the other species. The

  11. Photochemical reactions of chlorophyll in dehydrated photosystem II: two chlorophyll forms (680 and 700 nm).

    Science.gov (United States)

    Heber, Ulrich; Shuvalov, Vladimir A

    2005-06-01

    Lichens and phototolerant poikilohydric mosses differ from spinach leaves, fern fronds or photosensitive mosses in that they show strongly decreased Fo chlorophyll fluorescence after drying. This desiccation-induced fluorescence loss is rapidly reversible under rehydration. Fluorescence emission from Photosystem II at 685 nm was decreased more strongly by dehydration than 720 nm emission. Reaction centers of Photosystem II lose activity on dehydration and regain it on hydration. Heating of desiccated lichens increased Fo chlorophyll fluorescence. The activation energy for the reversible part of the temperature-dependent fluorescence increase was 0.045 eV, which corresponds to the energy difference between the 680 and 697 nm absorption bands. In desiccated chlorolichens such as Parmelia sulcata, heating induces the appearance of positive variable fluorescence related to the reversible reduction of QA due to overcoming the energy barrier. This is interpreted to provide information on the mechanism of photoprotection: energy is dissipated by changing Chl680 or P680 into a chlorophyll form, which absorbs at 700 nm and emits light at 720 nm (Chl-720 or P680(700)) with a low quantum yield. Dissipation of light energy in this trap is activated by desiccation. PMID:16049759

  12. Chlorophyll b degradation by chlorophyll b reductase under high-light conditions.

    Science.gov (United States)

    Sato, Rei; Ito, Hisashi; Tanaka, Ayumi

    2015-12-01

    The light-harvesting chlorophyll a/b binding protein complex of photosystem II (LHCII) is the main antenna complex of photosystem II (PSII). Plants change their LHCII content depending on the light environment. Under high-light conditions, the content of LHCII should decrease because over-excitation damages the photosystem. Chlorophyll b is indispensable for accumulating LHCII, and chlorophyll b degradation induces LHCII degradation. Chlorophyll b degradation is initiated by chlorophyll b reductase (CBR). In land plants, NON-YELLOW COLORING 1 (NYC1) and NYC1-Like (NOL) are isozymes of CBR. We analyzed these mutants to determine their functions under high-light conditions. During high-light treatment, the chlorophyll a/b ratio was stable in the wild-type (WT) and nol plants, and the LHCII content decreased in WT plants. The chlorophyll a/b ratio decreased in the nyc1 and nyc1/nol plants, and a substantial degree of LHCII was retained in nyc1/nol plants after the high-light treatment. These results demonstrate that NYC1 degrades the chlorophyll b on LHCII under high-light conditions, thus decreasing the LHCII content. After the high-light treatment, the maximum quantum efficiency of the PSII photochemistry was lower in nyc1 and nyc1/nol plants than in WT and nol plants. A larger light-harvesting system would damage PSII in nyc1 and nyc1/nol plants. The fluorescence spectroscopy of the leaves indicated that photosystem I was also damaged by the excess LHCII in nyc1/nol plants. These observations suggest that chlorophyll b degradation by NYC1 is the initial reaction for the optimization of the light-harvesting capacity under high-light conditions.

  13. Chlorophyll_Master

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set included chlorophyll for each subregion in the study (Georges Bank, Gulf of Maine, Southern New England, Middle Atlantic Bight) . The data came from...

  14. OSU Chlorophyll Bloom Product

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This product was developed for the Oregon coast based on the observed change between running 8-day composite chlorophyll-a (CHL) data obtained by the MODerate...

  15. Chlorophyll: The wonder pigment

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat, S.R.

    -in antioxidants. Inside, hidden by the dark green of the chlorophyll, vitamins, the SCIENCE REPORTER, July 2005 29 Feature Article Cluster of pigment molecules embedded in membrane Granum (stack of thylakoids) Porphyrin ring (light-absorbing "heod" of molecule... of enzymes that organize physiology inside a plant's body, turn glucose into all kinds of vitamins, antioxidants, and other chemical moieties and various biochemical reactions inside our body use glucose as fundamental source of energy! Chlorophyll is often...

  16. Investigating the allosteric reverse signalling of PARP inhibitors with microsecond molecular dynamic simulations and fluorescence anisotropy.

    Science.gov (United States)

    Marchand, Jean-Rémy; Carotti, Andrea; Passeri, Daniela; Filipponi, Paolo; Liscio, Paride; Camaioni, Emidio; Pellicciari, Roberto; Gioiello, Antimo; Macchiarulo, Antonio

    2014-10-01

    The inhibition of the poly(ADP-ribose) polymerase (PARP) family members is a strategy pursued for the development of novel therapeutic agents in a range of diseases, including stroke, cardiac ischemia, cancer, inflammation and diabetes. Even though some PARP-1 inhibitors have advanced to clinical setting for cancer therapy, a great deal of attention is being devoted to understand the polypharmacology of current PARP inhibitors. Besides blocking the catalytic activity, recent works have shown that some PARP inhibitors exhibit a poisoning activity, by trapping the enzyme at damaged sites of DNA and forming cytotoxic complexes. In this study we have used microsecond molecular dynamics to study the allosteric reverse signalling that is at the basis of such an effect. We show that Olaparib, but not Veliparib and HYDAMTIQ, is able to induce a specific conformational drift of the WGR domain of PARP-1, which stabilizes PARP-1/DNA complex through the locking of several salt bridge interactions. Fluorescence anisotropy assays support such a mechanism, providing the first experimental evidence that HYDAMTIQ, a potent PARP inhibitor with neuroprotective properties, is less potent than Olaparib to trap PARP-1/DNA complex.

  17. Interphase fluorescence in situ hybridization signal detection by computing intensity variance along the optical axis

    Science.gov (United States)

    Li, Zheng; Zheng, Bin; Ren, Liqiang; Liu, Hong

    2014-02-01

    Fluorescence in situ Hybridization technology is a commonly used tool to detect chromosome aberrations, which are often pathologically significant. Since manual FISH analysis is a tedious and time-consuming procedure, reliable and robust automated image acquisition and analysis are in demand. Under high magnification objective lenses such as 60x and 100x, the depth of field will often be too small and the FISH probes may not always lie in the same focal plane. A statistical variance based automated FISH analysis method is developed in order to address this problem. On a stack of slices at consecutive image planes with a step size d, the statistical variance alone the z-axis is calculated to form a 2-D matrix. Since pixels shift dramatically to high intensity at FISH probe location, the probes will manifest high peak values in the matrix. A computer-aided detection scheme based on top-hat transform is applied to the matrix to detect FISH probe signals. This study demonstrates a simple and robust method for FISH probe detection as well as a way of 2- D representation of 3-D data.

  18. G-quadruplex − based homogenous fluorescence platform for ultrasensitive DNA detection through isothermal cycling and cascade signal amplification

    International Nuclear Information System (INIS)

    We describe a simple and homogenous fluorimetric method for sensitive determination of DNA. It is based on target-triggered isothermal cycling and a cascade exponential amplification reaction that generates a large amount of a G-quadruplex. This results in strong fluorescence signal when using thioflavin T as a G-quadruplex-specific light-up fluorescent probe. Tedious handling after amplification is widely eliminated by the addition of thioflavin T. No other exogenous reagent is required. This detection platform is inexpensive and rapid, and displays high sensitivity for target DNA, with a detection limit as low as 91 pM. (author)

  19. 桑沟湾常见温带海草叶绿素荧光特性的比较%Chlorophyll fluorescence characteristics of common temperate seagrass species in Sanggou Bay

    Institute of Scientific and Technical Information of China (English)

    唐望; 方建光; 高亚平; 邹健; 吴桃; 杜美荣

    2012-01-01

    The chlorophyll fluorescence of the blades of three common seagrass species (Zostera marina, Z. caespitosa and Phyllospadix iwatensis) in eastern waters of Chudao, south coast of Sanggou Bay, was determined using the pulse amplitude modulated (PAM) fluo-rometer. The absorbance factor (AF) of seagrass blades were also determined,and the absolute electron transport rates of the seagrass species were calculated. It was found that the photosyn-thetic activity of Z. marina, Z. caespitosa and P. iwatensis, was strongly influenced by leaf age. The chlorophyll content and the AF values increased with blade age in respective plants. Young blades showed higher electron transport rate than older ones (Zm: Leaf 1 = 26. 56, Leaf 2 = 16.3, Leaf 3= 19.98; Pi: Leaf 1 =22.31, Leaf 2=19. 23, Leaf 3 = 17. 06; and Zc: Leaf 1 = 20. 16, Leaf 2 =16. 10,Leaf 3 = 13. 10). Among three species, Z. marina showed the highest photosynthetic activity (ETRmax=22. 67), in accordance with its highest productivity in the field compared with the other two species.%2011年7~8月在桑沟湾楮岛南岸东部海域,利用水下调制脉冲式荧光仪(DIVING-PAM)原位测定了中国北方3种常见温带海草大叶藻、丛生大叶藻以及红纤维虾海藻的不同叶龄叶片的叶绿素荧光特性,并确定了几种海草的吸光系数(AF)和叶片叶绿素含量,计算出海草绝对电子传递速率.实验结果表明,叶龄对海草的光合活性有较大影响,同种海草的AF值和叶绿素含量都随叶龄增加而增加,叶龄小的叶片明显具有较大的最大电子传递速率(ETRmx)(大叶藻∶叶1=26.56,叶2=21.45,叶3=19.98;红纤维虾海藻叶1=22.31,叶2=19.23,叶3=17.06;丛生叶藻∶叶1=20.16,叶2=16.10;叶3=13.10).相比于丛生大叶藻和红纤维虾形藻,大叶藻具有最高的光合活性(ETRmax=22.67),这也与大叶藻在3种海草中所具有最高的初级生产力是相符合的.

  20. Marine fluorescence from high spectrally resolved satellite measurements

    Science.gov (United States)

    Wolanin, Aleksandra; Dinter, Tilman; Rozanov, Vladimir; Noël, Stefan; Vountas, Marco; Burrows, John P.; Bracher, Astrid

    2014-05-01

    ). Based on the simulated data, we also calculated corrections the influence of for water vapor, Raman scattering and solar zenith angle on the retrieved fluorescence emissions. Our fluorescence results from SCIAMACHY and GOME-2 show similar spatial patterns when compared to the MODIS FLH. The fluorescence is generally stronger in areas of high chlorophyll concentration. The observed differences between SCIAMACHY and GOME-2 DOAS FLH and MODIS FLH arise from differences among instruments, retrieval methods, spatial and temporal sampling and overpass time. Our hyperspectral retrieval shows noisier results than MODIS FLH, but is not susceptible to certain problems as the multispectral FLH, which arise from backscattered light by particulate matter or phycocyanin fluorescence (Abbott and Letelier, 1999). For our fluorescence retrieval, we acquired better quality for the SCIAMACHY data than for GOME-2, due to the higher spectral resolution and the smaller size of the footprint. Our results demonstrate that it is feasible to detect the weak fluorescence signal from the oceans within hyperspectral data from satellite measurements. The method presented is generic and can be applied to other instruments in the future.

  1. An optimised method for correcting quenched fluorescence yield

    Directory of Open Access Journals (Sweden)

    L. Biermann

    2014-05-01

    Full Text Available Under high light intensity, phytoplankton protect their photosystems from bleaching through non-photochemical quenching processes. The consequence of this is suppression of fluorescence emission, which must be corrected when measuring in situ yield with fluorometers. Previously, this has been done using the limit of the mixed layer, assuming that phytoplankton are uniformly mixed from the surface to this depth. However, the assumption of homogeneity is not robust in oceanic regimes that support deep chlorophyll maxima. To account for these features, we correct from the limit of the euphotic zone, defined as the depth at which light is at ~1% of the surface value. This method was applied to fluorescence data collected by eleven animal-borne fluorometers deployed in the Southern Ocean over four austral summers. Six tags returned data showing evidence of deep chlorophyll features. Using the depth of the euphotic layer, quenching was corrected without masking subsurface fluorescence signals.

  2. An optimised method for correcting quenched fluorescence yield

    Science.gov (United States)

    Biermann, L.; Guinet, C.; Bester, M.; Brierley, A.; Boehme, L.

    2014-05-01

    Under high light intensity, phytoplankton protect their photosystems from bleaching through non-photochemical quenching processes. The consequence of this is suppression of fluorescence emission, which must be corrected when measuring in situ yield with fluorometers. Previously, this has been done using the limit of the mixed layer, assuming that phytoplankton are uniformly mixed from the surface to this depth. However, the assumption of homogeneity is not robust in oceanic regimes that support deep chlorophyll maxima. To account for these features, we correct from the limit of the euphotic zone, defined as the depth at which light is at ~1% of the surface value. This method was applied to fluorescence data collected by eleven animal-borne fluorometers deployed in the Southern Ocean over four austral summers. Six tags returned data showing evidence of deep chlorophyll features. Using the depth of the euphotic layer, quenching was corrected without masking subsurface fluorescence signals.

  3. Centimeter-deep tissue fluorescence microscopic imaging with high signal-to-noise ratio and picomole sensitivity

    CERN Document Server

    Cheng, Bingbing; Wei, Ming-Yuan; Pei, Yanbo; DSouza, Francis; Nguyen, Kytai T; Hong, Yi; Tang, Liping; Yuan, Baohong

    2015-01-01

    Fluorescence microscopic imaging in centimeter-deep tissue has been highly sought-after for many years because much interesting in vivo micro-information, such as microcirculation, tumor angiogenesis, and metastasis, may deeply locate in tissue. In this study, for the first time this goal has been achieved in 3-centimeter deep tissue with high signal-to-noise ratio (SNR) and picomole sensitivity under radiation safety thresholds. These results are demonstrated not only in tissue-mimic phantoms but also in actual tissues, such as porcine muscle, ex vivo mouse liver, ex vivo spleen, and in vivo mouse tissue. These results are achieved based on three unique technologies: excellent near infrared ultrasound-switchable fluorescence (USF) contrast agents, a sensitive USF imaging system, and an effective correlation method. Multiplex USF fluorescence imaging is also achieved. It is useful to simultaneously image multiple targets and observe their interactions. This work opens the door for future studies of centimeter...

  4. Crystal Structures of the GCaMP Calcium Sensor Reveal the Mechanism of Fluorescence Signal Change and Aid Rational Design

    Energy Technology Data Exchange (ETDEWEB)

    Akerboom, Jasper; Velez Rivera, Jonathan D.; Rodriguez Guilbe, María M.; Alfaro Malavé, Elisa C.; Hernandez, Hector H.; Tian, Lin; Hires, S. Andrew; Marvin, Jonathan S.; Looger, Loren L.; Schreiter, Eric R.; (MIT); (Puerto Rico); (HHMI)

    2009-03-16

    The genetically encoded calcium indicator GCaMP2 shows promise for neural network activity imaging, but is currently limited by low signal-to-noise ratio. We describe x-ray crystal structures as well as solution biophysical and spectroscopic characterization of GCaMP2 in the calcium-free dark state, and in two calcium-bound bright states: a monomeric form that dominates at intracellular concentrations observed during imaging experiments and an unexpected domain-swapped dimer with decreased fluorescence. This series of structures provides insight into the mechanism of Ca{sup 2+}-induced fluorescence change. Upon calcium binding, the calmodulin (CaM) domain wraps around the M13 peptide, creating a new domain interface between CaM and the circularly permuted enhanced green fluorescent protein domain. Residues from CaM alter the chemical environment of the circularly permuted enhanced green fluorescent protein chromophore and, together with flexible inter-domain linkers, block solvent access to the chromophore. Guided by the crystal structures, we engineered a series of GCaMP2 point mutants to probe the mechanism of GCaMP2 function and characterized one mutant with significantly improved signal-to-noise. The mutation is located at a domain interface and its effect on sensor function could not have been predicted in the absence of structural data.

  5. Using genetically encoded fluorescent reporters to image lipid signalling in living plants

    NARCIS (Netherlands)

    J.E.M. Vermeer; T. Munnik

    2013-01-01

    The discovery of the green fluorescent protein has revolutionized cell biology as it allowed researchers to visualize dynamic processes in living cells. The fusion of fluorescent protein variants with lipid binding domains that bind to specific phospholipids have been very instrumental in investigat

  6. Single Molecule Detection of H2O2 Mediating Angiogenic Redox Signaling on Fluorescent Single-Walled Carbon Nanotube Array

    OpenAIRE

    Kim, Jong-Ho; Arkalgud, Jyoti R.; Boghossian, Ardemis A; Zhang, Jingqing; Han, Jae-Hee; Reuel, Nigel F.; Ahn, Jin-Ho; Mukhopadhyay, Debabrata; Strano, Michael S.

    2011-01-01

    Reactive oxygen species, specifically hydrogen peroxide (H2O2), activate signal transduction pathways during angiogenesis, and therefore play an important role in physiological development as well as various pathophysiologies. Herein, we utilize a near infrared fluorescent single-walled carbon nanotube (SWNT) sensor array to measure the single molecule efflux of H2O2 from human umbilical vein endothelial cells (HUVEC) in response to angiogenic stimulation. Two angiogenic agents were investiga...

  7. Cleavable DNA-protein hybrid molecular beacon: A novel efficient signal translator for sensitive fluorescence anisotropy bioassay.

    Science.gov (United States)

    Hu, Pan; Yang, Bin

    2016-01-15

    Due to its unique features such as high sensitivity, homogeneous format, and independence on fluorescent intensity, fluorescence anisotropy (FA) assay has become a hotspot of study in oligonucleotide-based bioassays. However, until now most FA probes require carefully customized structure designs, and thus are neither generalizable for different sensing systems nor effective to obtain sufficient signal response. To address this issue, a cleavable DNA-protein hybrid molecular beacon was successfully engineered for signal amplified FA bioassay, via combining the unique stable structure of molecular beacon and the large molecular mass of streptavidin. Compared with single DNA strand probe or conventional molecular beacon, the DNA-protein hybrid molecular beacon exhibited a much higher FA value, which was potential to obtain high signal-background ratio in sensing process. As proof-of-principle, this novel DNA-protein hybrid molecular beacon was further applied for FA bioassay using DNAzyme-Pb(2+) as a model sensing system. This FA assay approach could selectively detect as low as 0.5nM Pb(2+) in buffer solution, and also be successful for real samples analysis with good recovery values. Compatible with most of oligonucleotide probes' designs and enzyme-based signal amplification strategies, the molecular beacon can serve as a novel signal translator to expand the application prospect of FA technology in various bioassays.

  8. Cleavable DNA-protein hybrid molecular beacon: A novel efficient signal translator for sensitive fluorescence anisotropy bioassay.

    Science.gov (United States)

    Hu, Pan; Yang, Bin

    2016-01-15

    Due to its unique features such as high sensitivity, homogeneous format, and independence on fluorescent intensity, fluorescence anisotropy (FA) assay has become a hotspot of study in oligonucleotide-based bioassays. However, until now most FA probes require carefully customized structure designs, and thus are neither generalizable for different sensing systems nor effective to obtain sufficient signal response. To address this issue, a cleavable DNA-protein hybrid molecular beacon was successfully engineered for signal amplified FA bioassay, via combining the unique stable structure of molecular beacon and the large molecular mass of streptavidin. Compared with single DNA strand probe or conventional molecular beacon, the DNA-protein hybrid molecular beacon exhibited a much higher FA value, which was potential to obtain high signal-background ratio in sensing process. As proof-of-principle, this novel DNA-protein hybrid molecular beacon was further applied for FA bioassay using DNAzyme-Pb(2+) as a model sensing system. This FA assay approach could selectively detect as low as 0.5nM Pb(2+) in buffer solution, and also be successful for real samples analysis with good recovery values. Compatible with most of oligonucleotide probes' designs and enzyme-based signal amplification strategies, the molecular beacon can serve as a novel signal translator to expand the application prospect of FA technology in various bioassays. PMID:26592607

  9. Chlorophyll formation and phytochrome

    NARCIS (Netherlands)

    Raven, C.W.

    1973-01-01

    The rôle of phytochrome in the regeneration of protochlorophyll (Pchl) in darkness following short exposures to light, as well as in the accumulation of chlorophyll- a (Chl- a ) in continuous light in previously dark-grown seedlings of pea, bean, and maize has been the subject of the present investi

  10. Modulation of fluorescence signals from biomolecules along nanowires due to interaction of light with oriented nanostructures

    DEFF Research Database (Denmark)

    Frederiksen, Rune Schøneberg; Alarcon-Llado, Esther; Madsen, Morten H.;

    2015-01-01

    High aspect ratio nanostructures have gained increasing interest as highly sensitive platforms for biosensing. Here, well-defined biofunctionalized vertical indium arsenide nanowires are used to map the interaction of light with nanowires depending on their orientation and the excitation waveleng....... We show how nanowires act as antennas modifying the light distribution and the emitted fluorescence. This work highlights an important optical phenomenon in quantitative fluorescence studies and constitutes an important step for future studies using such nanostructures....

  11. A two-photon fluorescent probe with a large turn-on signal for imaging hydrogen sulfide in living tissues

    International Nuclear Information System (INIS)

    Highlights: • A two-photon fluorescent probe for sensing H2S was developed. • The probe shows a large turn on signal (120-fold enhancement). • The probe is suitable for fluorescence imaging of H2S in living cells and tissues. • The probe was capable of detecting H2S up to 170 μm depth in live tissues. - Abstract: A two-photon fluorescence turn-on H2S probe GCTPOC–H2S based on a two-photon platform with a large cross-section, GCTPOC, and a sensitive H2S recognition site, dinitrophenyl ether was constructed. The probe GCTPOC–H2S exhibits desirable properties such as high sensitivity, high selectivity, functioning well at physiological pH and low cytotoxicity. In particular, the probe shows a 120-fold enhancement in the presence of Na2S (500 μM), which is larger than the reported two-photon fluorescent H2S probes. The large fluorescence enhancement of the two-photon probe GCTPOC–H2S renders it attractive for imaging H2S in living tissues with deep tissue penetration. Significantly, we have demonstrated that the probe GCTPOC–H2S is suitable for fluorescence imaging of H2S in living tissues with deep penetration by using two-photon microscopy. The further application of the two-photon probe for the investigation of biological functions and pathological roles of H2S in living systems is under progress

  12. Pulse amplitude modulated chlorophyll fluorometer

    Science.gov (United States)

    Greenbaum, Elias; Wu, Jie

    2015-12-29

    Chlorophyll fluorometry may be used for detecting toxins in a sample because of changes in micro algae. A portable lab on a chip ("LOAC") based chlorophyll fluorometer may be used for toxin detection and environmental monitoring. In particular, the system may include a microfluidic pulse amplitude modulated ("PAM") chlorophyll fluorometer. The LOAC PAM chlorophyll fluorometer may analyze microalgae and cyanobacteria that grow naturally in source drinking water.

  13. An Analysis of Chlorophyll Fluorescence Parameters and Protein Expression Levels in PSⅡof Cassava%华南系列木薯叶绿素荧光参数及光系统Ⅱ相关蛋白表达水平分析

    Institute of Scientific and Technical Information of China (English)

    陈霆; 李开绵; 安飞飞; 周建国; 魏艳

    2014-01-01

    以华南205( cv.SC205)为对照,研究7个华南系列木薯品种华南5号( cv.SC5)、华南6号( cv.SC6)、华南7号(cv.SC7)、华南8号(cv.SC8)、华南9号(cv.SC9)、华南10号(cv.SC10)、华南11号(cv.SC11)的叶绿素含量、叶绿素荧光参数及光系统Ⅱ( PSⅡ)中相关蛋白表达水平的差异。结果表明:SC6叶片叶绿素a、叶绿素b及总叶绿素含量均显著低于对照SC205及其它6个品种;叶绿素荧光参数中ΦPSⅡ显示8个木薯品种PSⅡ的实际光合效率Φ从高到低顺序为ΦSC5、ΦSC8、ΦSC9、ΦSC10、ΦSC205、ΦSC11、ΦSC7、ΦSC6。 Western Blot结果表明D1蛋白、放氧复合体(OEC)及核酮糖-1,5-二磷酸羧化酶/加氧酶(Rubisco)均在SC6叶片中表达最低,而在SC5、SC8、SC9叶片中表达较高。叶绿素荧光参数及PSⅡ相关蛋白可为高效选育木薯优良品种提供参考。%In order to detect the chlorophyll content ,chlorophyll fluorescence parameters and protein ex-pression levels related with PSⅡ in different cassava varieties , SCATC5 ( cv.SC5 ) , SCATC6 ( cv.SC6 ) , SCATC7 (cv.SC7),SCATC8 (cv.SC8),SCATC9 (cv.SC9),SCATC10 (cv.SC10),SCATC11 (cv.SC11), SCATC205 (cv.SC205) were studied in this experiment,and SC205 (cv.SC205) was the control as CK.The results showed that the contents of chlorophyll a ,chlorophyll b and total chlorophyll of SC 6 were significantly lower than that of the control cv .SC205 and those of the other six cassava varieties .The chlorophyll fluorescence parameters of ΦP SⅡ revealed that the actual photosynthetic efficiency order of 8 cassava varieties from high to low was ΦSC5 ,ΦSC8 ,ΦSC9 ,ΦSC10 ,ΦSC205 ,ΦSC11 ,ΦSC7 ,ΦSC6 .The western Blot results showed that the expression levels of D1 protein,oxygen-evolving complex ( OEC) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) were the lowest in cv.SC6 leaves,but higher in cv.SC5,cv.SC8,cv.SC9 leaves.Chlorophyll

  14. 基于叶绿素荧光技术的紫菜光适应特征研究%Light adaptation characteristics of porphyra studied by chlorophyll fluorescence technology

    Institute of Scientific and Technical Information of China (English)

    张涛; 沈宗根; 姚春燕; 陆勤勤; 姜红霞; 朱建一; 许璞

    2011-01-01

    通过水样调制式叶绿素荧光仪,对坛紫菜、条斑紫菜叶状体和丝状体在不同光照条件下叶绿素荧光特性进行研究.结果表明:紫菜叶状体和丝状体实际量子效率在光照处理后逐步下降,且随着处理光强的上升,实际量子效率的下降速率更为明显.快速光曲线初始斜率(α)结果与实际量子效率相似,表明光照时间的延长以及光照强度的升高均引起样品实际光能利用效率的下降.快速光曲线结果也显示样品半饱和光强低于150 μmol/(m2·s),说明紫菜这类海藻偏向较低光强的适应性.随着处理光强的上升,样品Ik值逐步升高,说明紫菜具备适应光强变化的光能调节机制.方差分析结果表明,两种紫菜丝状体实际量子效率、快速光曲线初始斜率(α)和最大相对电子传递速率均因光强的上升而显著降低(P<0.05),叶状体实际量子效率、快速光曲线初始斜率也随光强上升而下降,但最大相对电子传递速率基本维持不变,表明紫菜两个生长世代的藻体对光强具有不同的响应机制.诱导曲线测定结果表明,经强光适应的紫菜叶状体光化学猝灭较高,而非光化学猝灭较低,显示强光处理能够提高叶状体对光强的适应能力.%The chlorophyll fluorescence characteristics of thallus and eonchocelis in both species of Por phyra grown under different light intensities were investigated with Water-PAM chlorophyll fluorometer.Results showed that the effective quantum yield of PSⅡ (Yield) of Porphyra decreased after the treatment, and the effective quantum yield of sample decreased obviously with the increasing of light intensity.Results of the initial slop of rapid light cnrvc (α) are sirnilar with the effective quantum yield of sample,which meant both the time after treatment and the increasing of light intensities Would induce the decreasing of actual light energy use efficieney of Porphyra.lhe minimum saturating

  15. Reverse Fluorescence Enhancement and Colorimetric Bimodal Signal Readout Immunochromatography Test Strip for Ultrasensitive Large-Scale Screening and Postoperative Monitoring.

    Science.gov (United States)

    Yao, Yingyi; Guo, Weisheng; Zhang, Jian; Wu, Yudong; Fu, Weihua; Liu, Tingting; Wu, Xiaoli; Wang, Hanjie; Gong, Xiaoqun; Liang, Xing-Jie; Chang, Jin

    2016-09-01

    Ultrasensitive and quantitative fast screening of cancer biomarkers by immunochromatography test strip (ICTS) is still challenging in clinic. The gold nanoparticles (NPs) based ICTS with colorimetric readout enables a quick spectrum screening but suffers from nonquantitative performance; although ICTS with fluorescence readout (FICTS) allows quantitative detection, its sensitivity still deserves more efforts and attentions. In this work, by taking advantages of colorimetric ICTS and FICTS, we described a reverse fluorescence enhancement ICTS (rFICTS) with bimodal signal readout for ultrasensitive and quantitative fast screening of carcinoembryonic antigen (CEA). In the presence of target, gold NPs aggregation in T line induced colorimetric readout, allowing on-the-spot spectrum screening in 10 min by naked eye. Meanwhile, the reverse fluorescence enhancement signal enabled more accurately quantitative detection with better sensitivity (5.89 pg/mL for CEA), which is more than 2 orders of magnitude lower than that of the conventional FICTS. The accuracy and stability of the rFICTS were investigated with more than 100 clinical serum samples for large-scale screening. Furthermore, this rFICTS also realized postoperative monitoring by detecting CEA in a patient with colon cancer and comparing with CT imaging diagnosis. These results indicated this rFICTS is particularly suitable for point-of-care (POC) diagnostics in both resource-rich and resource-limited settings. PMID:27547984

  16. 外源NO对NaCl胁迫下长春花幼苗生物量和叶绿素荧光的影响%Effects of exogenous nitric oxide on biomass and chlorophyll fluorescence of Catharanthus roseus seedlings under NaCl stress

    Institute of Scientific and Technical Information of China (English)

    胡凡波; 刘玲; 隆小华; 刘兆普

    2011-01-01

    A pot experiment in greenhouse was carried out to study the effects of different concentration exogenous NO donor ( sodium nitroprusside, SNP) on the biomass, chlorophyll content, and chlorophyll fluorescence of Catharanthus roseus seedlings under the stress of 50 mmol NaCl · L-1. Among the treatments with SNP, the seedlings treated with 50 mmol NaCl · L-1+ 0. 1 mmol SNP · L-1 had the highest fresh weight and dry weight, being significantly higher (18. 8% and 13. 9% , respectively) than the control (50 mmol NaCl · L-1). Similar to biomass, the chlorophyll a, chlorophyll b, and carotenoid contents in treatment 50 mmol NaCl · L-1 + 0. 1 mmol SNP · L-1 were the highest, but had no significant differences with the control. The variation trend of chlorophyll a/b was more complicated. Applying 0. 1 mmol · L-1 of SNP had the best effect in mitigating the salt damage to Ps Ⅱ reaction center, which increased the fluorescence ( Fv ) , maximal fluorescence ( Fm ) , light energy transformation efficiency of PS Ⅱ ( Fv/Fm ) , activity potential of PS Ⅱ ( Fv/Fo) , actual photochemical efficiency of PS Ⅱ ( (¢)PSⅡ ) , and photochemical quenching (qp) markedly, and decreased the minimal fluorescence (Fo) and non-photochemical quenching (qN) obviously. To sum up, 0. 1 mmol · L-1 of SNP had the best effect in protecting chlorophyll and PS Ⅱ reaction center against salt damage, and also, could promote the growth of the seedlings and enhance their tolerance to 50 mmol Ⅱ L-1 NaCl stress.%在温室条件下采用盆栽法,研究了50mmol· L-1 NaCl胁迫下5个不同浓度外源NO供体硝普钠(sodium nitroprusside,SNP)对长春花(Catharanthus roseus)幼苗生物量、叶绿素含量和叶绿素荧光的影响.结果表明:(1)鲜重和干重均在S2(50mmol·L-1NaCl+0.1mmol·L-1SNP)处理下达到最高,分别较对照So(50mmol·L-1 NaCl)显著增加18.8%和13.9%.叶绿素a、叶绿素b和类胡萝卜素与生物量相似,均在S2处理下

  17. Comparison of Chlorophyll Fluorescence Parameter between a New Male Sterile Germplasm and its Maintainer Line in Pak-choi%不结球白菜雄性不育新种质及其保持系的叶绿素荧光参数比较

    Institute of Scientific and Technical Information of China (English)

    朱红芳; 侯瑞贤; 李晓锋; 朱玉英; 王真真

    2013-01-01

    利用叶绿素荧光技术,在4个不同时期分别测定不结球白菜雄性不育新种质及其保持系的各叶绿素荧光参数,以及叶绿素的SPAD值.结果表明:不育系在生长的不同时期,叶绿素含量的变化与保持系一致,且差异不显著;初始荧光Fo、最大光化学效率(Fv/Fm)、实际光化学效率(φPSⅡ)、光化学淬灭系数(qP)和非光化学淬灭系数(qN),不育系与保持系在各时期的变化趋势一致,但在抽薹期和开花期存在差异,表明该不结球白菜的不育系与保持系在营养生长过程中植物学性状一致,生殖生长期的差异可能与其不育性有关.%The chlorophyll fluorescence parameters and the content of chlorophyll SPAD both in male sterile germplasm in Pak-choi (Brassica campestris ssp. chinensis Makino L.) and its maintainer line were measured by chlorophyll fluorescence technique in four different periods. The results showed that the changes of chlorophyll SPAD in the male sterile line is similar with its maintainer in different growth periods. These parameters including the initial fluorescence Fo, maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency (φPPSⅡ), photochemical quenching coefficient ( qP ),and non-photochemical quenching coefficient (qN) demonstrated similar changing trends in sterile strain and maintainer in different growing period. However, during bud and blossom period, these indexes showed obvious differences,indicating that the new germplasm from male sterile line had the same botany character with its maintainer line in vegetative growth period. The difference in reproductive growth was associated with male sterility.

  18. 农药胁迫对生菜叶片叶绿素荧光图像参数的影响%Effects of Pesticides on Chlorophyll Fluorescence Image Parameters of Lettuce Leaves

    Institute of Scientific and Technical Information of China (English)

    孙俊; 宋彩惠; 毛罕平; 金夏明; 方敏; 张梅霞

    2014-01-01

    对生菜(Lactuca sativa)分别均匀喷洒浓度为70、140、280μg/L的杀虫剂氰戊菊酯,以清水为对照,以意大利全年耐抽薹生菜为试材,结果表明,随着农药浓度的增加,光系统Ⅱ的最大光化学效率、实际光化学效率、光化学淬灭系数和相对电子传递速率均下降,非光化学淬灭系数、非调节性能量耗散的量子产额和调节性能量耗散的量子产额上升,综合影响造成光系统Ⅱ的中心活性区域缩小、光合速率下降。另外生菜叶片自身的光化合保护机制能在一定程度上减轻农药的胁迫作用。与对照相比,光系统Ⅱ的实际光化学效率受农药影响最大,喷洒浓度为280μg/L的杀虫剂会对生菜光合作用过程产生持续性的、不可逆转的影响。%The Italy lettuce samples were sprayed evenly with water and pesticide fenvalerate with concentrations of 70,140,280 μg/L to study the adverse effect of pesticide on chlorophyll fluorescence parameters of lettuce leaves.With the increase of concentration of pesticide sprayed on the lettuce leaves,the biggest photosynthetic efficiency of photosystem Ⅱ(Fv/Fm),actual photosynthetic efficiency YI,photochemical quenching coefficient (qP) and relative electron transport rate declined and showed a clear decrease,meanwhile the non-photochemical quenching coefficient (qN),regulatory quantum yield of energy dissipation (Y NPQ) and non-regulatory quantum yield of energy dissipation (Y NO) increased significantly. Because of these disturbances,centre activity area of photosystem Ⅱ and actual photochemical efficiency was reduced. Light protection mechanisms of the lettuce leaves alleviated the impact of pesticides to a certain extent.Compared with control group,the actual photosynthetic efficiency of photosystem Ⅱ was one of the most exposed to effects from pesticide.The influence of 280μg/L pesticides on lettuce photosynthesis was continuous and irreversible.

  19. 两种岩白菜属植物叶绿素荧光及其叶绿素含量分析%Chlorophyll Fluorescence and its Contents in Two Types of Bergeni

    Institute of Scientific and Technical Information of China (English)

    刘彦汐; 高泽梅; 郭强; 权秋梅; 黎云祥

    2015-01-01

    By using Li - 6400 portable photosynthesis meter and spectrophotometer,the parameters of chloro-phyll fluorescence and its content in Bergenia tianquaninsis J. T. Pan and Bergenia purpurascens Engl. were deter-mined. The results showed:1)the lateral reactivity of PSⅡwas 0. 815 for B. tianquaninsis J. T. Pan and 0. 806 for B. purpurascens Engl. ,which showed significant difference between B. tianquaninsis J. T. Pan and B. pur-purascens Engl. . there was no photoinhibition(P 0. 05). and 4)The contents of chlorophy a,carote-noids,the ratios of chlorophy a to chlorophy b,the ratios of carotenoid to chlorophyⅡin B. tianquaninsis J. T. Pan were greater than those in B. purpurascens Engl. ,but thechlorophy b in B. tianquaninsis J. T. Pan was lower than that in B. purpurascens Engl.(P < 0. 01). It means that the capacity of light - harvesting and heat dissipa-tion capability under the strong light in B. tianquaninsis J. T. Pan was greater than those in B. purpurascens En-gl. ,which further illustrates the photosynthetic capacity of B. tianquaninsis J. T. Pan was stronger than that in B. purpurascens Engl. .%以移栽的天全岩白菜(Bergenia tianquanensis J. T. Pan)和岩白菜(Bergenia purpurascens Engl.)为材料,利用 LI -6400便携式光合测定仪和分光光度计,分别测定两种岩白菜属植物的叶绿素荧光参数及叶绿素含量.结果表明:(1)天全岩白菜与岩白菜的 PSⅡ潜在活性分别为0.815和0.806,差异极显著(P <0.01),均没有发生光抑制现象;(2)PSⅡ有效光化学量子产量及 PSⅡ的潜在活性大于岩白菜,且差异极显著(P <0.01);而天全岩白菜的光化学淬灭显著小于岩白菜,非光化学淬灭系数也小于岩白菜,且差异显著( P <0.05);(3)表观光合电子传递速率与光存在时 PSⅡ实际的光化学量子效率在天全岩白菜和岩白菜之间不存在显著性差异(P >0.05);(4

  20. Compare of chlorophyll fluorescence characteristics between vegetative and germ cells of Porphyra haitanensis%坛紫菜叶状体营养细胞与生殖细胞叶绿素荧光特性比较

    Institute of Scientific and Technical Information of China (English)

    李家富; 张涛; 陆勤勤; 朱建一; 沈宗根; 刘兆普; 王长海

    2013-01-01

      Light utilization characteristics of vegetative and germ cells of Porphyra haitanensis were compared by technique of chlorophyll fluorescence. The results showed that the actual photochemical efficiency of PSII (ΔF/Fm´) of the vegetative cells and female cells exhibited only a little difference, but they were both significantly higher than that of the male cells. The maximum relative electron transport rate (rETRmax) of the vegetative cells and fe-male cells were both significantly higher than that of the male cells. There was no significant difference in half saturating irradiance (Ik) between the vegetative and germ cells. The vegetative cells and female cells had similar rETR, photochemical quenching (qP) and non-photochemical quenching (NPQ) under the growing light intensity, which were higher than those of the male cells. These results suggested that the vegetative cells and female cells of P. haitanensis could use light efficiently and most of absorbed light energy was used for photosynthetic electron transport, but the male cells had much lower light energy use efficiency.%  利用叶绿素荧光技术对坛紫菜(Porphyra haitanensis)叶状体营养细胞和生殖细胞的光能利用特性进行了比较。结果表明:坛紫菜叶状体营养细胞和雌性生殖细胞的实际量子效率(ΔF/Fm′)差异不明显,但显著高于雄性生殖细胞;快速光曲线测定表明雌、雄藻体营养细胞的最大相对电子传递速率(rETRmax)相近,但显著高于雄性生殖细胞;不同生殖细胞半饱和光强(Ik)无显著差异;在生长光强下,营养细胞和雌性生殖细胞rETR、光化学猝灭(qP)和非光化学猝灭(NPQ)差异不明显,而雄性生殖细胞rETR、qP等荧光参数均显著低于营养细胞和雌性生殖细胞。本文表明坛紫菜叶状体营养细胞和雌性生殖细胞具有较高的光能利用能力,能够将吸收的光能多数用于电子传递,而雄性生殖细胞对光能的利用能力较低。

  1. As clorofilas The chlorophylls

    Directory of Open Access Journals (Sweden)

    Nivia Maria Streit

    2005-06-01

    Full Text Available As clorofilas são pigmentos verdes, comuns em todas as células fotossintéticas. Por sua estrutura química ser instável, são facilmente degradadas, resultando em produtos de decomposição que modificam a percepção e qualidade dos alimentos. Esta revisão trata dos vários fatores que interferem na degradação das clorofilas, como a luz, radiação, calor, ácidos, oxigênio, alteração enzimática e interação com outros pigmentos. Também, outro aspecto a ser abordado é a utilização das clorofilas como corantes, através da formação de complexos que tornam esses pigmentos mais estáveis à decomposição.The Chlorophylls are a common green pigment to all photosynthetic cells. They are easily degraded, because of their unstable chemical structure. Degradation results in products alter the perception and quality of foods. This review discusses the various factors, that interfere on chlorophyll degradation such as light, irradiation, heat, acids, oxygen, enzymatical alteration and the interaction with other pigments. Also, the other topic that was mentioned the utilization of the chlorophylls as dyes through a complex formation that make this pigment more stable to degradation.

  2. An algorithm for computing chlorophyll-a concentrations using a dual-frequency fluorosensor

    Science.gov (United States)

    Campbell, J. W.

    1981-01-01

    An algorithm to be used on data from a dual-frequency fluorosensor (i.e. one using two wavelengths for excitation of chlorophyll-a fluorescence) to compute total chlorophyll-a concentration and to partition that chlorophyll between two color groups present in a mixed phytoplankton population is described. The algorithm is based on laboratory and field-testing experience gained with the airborne lidar oceanographic probing experiment fluorosensor.

  3. Use of independent component analysis to improve signal-to-noise ratio in multi-probe fluorescence microscopy.

    Science.gov (United States)

    Dao, L; Lucotte, B; Glancy, B; Chang, L-C; Hsu, L-Y; Balaban, R S

    2014-11-01

    In conventional multi-probe fluorescence microscopy, narrow bandwidth filters on detectors are used to avoid bleed-through artefacts between probes. The limited bandwidth reduces the signal-to-noise ratio of the detection, often severely compromising one or more channels. Herein, we describe a process of using independent component analysis to discriminate the position of different probes using only a dichroic mirror to differentiate the signals directed to the detectors. Independent component analysis was particularly effective in samples where the spatial overlap between the probes is minimal, a very common case in cellular microscopy. This imaging scheme collects nearly all of the emitted light, significantly improving the image signal-to-noise ratio. In this study, we focused on the detection of two fluorescence probes used in vivo, NAD(P)H and ANEPPS. The optimal dichroic mirror cutoff frequency was determined with simulations using the probes spectral emissions. A quality factor, defined as the cross-channel contrast-to-noise ratio, was optimized to maximize signals while maintaining spatial discrimination between the probes after independent component analysis post-processing. Simulations indicate that a ∼3 fold increase in signal-to-noise ratio using the independent component analysis approach can be achieved over the conventional narrow-band filtering approach without loss of spatial discrimination. We confirmed this predicted performance from experimental imaging of NAD(P)H and ANEPPS in mouse skeletal muscle, in vivo. For many multi-probe studies, the increased sensitivity of this 'full bandwidth' approach will lead to improved image quality and/or reduced excitation power requirements.

  4. Homogeneous Time-Resolved Fluorescence-Based Assay to Monitor Extracellular Signal-Regulated Kinase Signalling in a High-Throughput Format

    Directory of Open Access Journals (Sweden)

    Mohammed Akli eAyoub

    2014-06-01

    Full Text Available The extracellular signal-regulated kinases (ERKs are key components of multiple important cell signalling pathways regulating diverse biological responses. This signalling is characterized by phosphorylation cascades leading to ERK1/2 activation and promoted by various cell surface receptors including G protein-coupled receptors (GPCRs and receptor tyrosine kinases (RTKs. We report the development of a new cell-based phospho-ERK1/2 assay (designated Phospho-ERK, which is a sandwich proximity-based assay using the homogeneous time-resolved fluorescence technology. We have validated the assay on endogenously expressed ERK1/2 activated by the epidermal growth factor (EGFR as a prototypical RTK, as well as various GPCRs belonging to different classes and coupling to different heterotrimeric G proteins. The assay was successfully miniaturized in 384-well plates using various cell lines endogenously, transiently or stably expressing the different receptors. The validation was performed for agonists, antagonists and inhibitors in dose-response as well as kinetic analysis, and the signalling and pharmacological properties of the different receptors were reproduced. Furthermore, the determination of a Z’-factor value of 0.7 indicates the potential of the Phospho-ERK assay for high-throughput screening of compounds that may modulate ERK1/2 signalling. Finally, our study is of great interest in the current context of investigating ERK1/2 signalling with respect to the emerging concepts of biased ligands, G protein-dependent/independent ERK1/2 activation, and functional transactivation between GPCRs and RTKs, illustrating the importance of considering the ERK1/2 pathway in cell signalling.

  5. 氮素水平对转C4光合基因水稻花期剑叶PSⅡ荧光特性的影响%Responses of Chlorophyll Fluorescence Characteristics to Nitrogen in Flag Leaves of C4 Photosynthetic Enzymes Transgenic Rice during the Reproductive Stage

    Institute of Scientific and Technical Information of China (English)

    魏晓东; 李霞; 郭士伟; 陈平波

    2013-01-01

    There was close relationship between nitrogen use efficiency and photosynthetic capability. C4 photo-synthetic gene transgenic rice had higher light use efficiency and CO2 assimilation compared to traditional C3 rice cultivars. However, whether nitrogen had influence on photosynthesis of these transgenic rice cultivars was unknown Chlorophyll fluorescence can reflect intrinsic characteristics using fast measurement without any damage to leaves, and is usually used as probe of photosynthesis. In the present study, the pepc (PC) ,ppdk (PK)and pepc + ppdk (CK) transgenic rice plants were used as experimental materials with their wild type Kitaaki( WT) to investigate the responses of photosynthetic characteristics to different nitrogen levels in C4 photosynthetic gene transgenic rice at the late reproductive stage. Changes in SPAD values, morphological parameters were measured in flag leaves of four cultivars under different nitrogen levels. The analysis of chlorophyll fluorescence kinetic curves and some related parameters were also done under three nitrogen levels(0. 7 mmol/L N-1/4N low nitrogen,3 mmol/L N-1N control, 6 mmol/L N-2N high nitrogen)at the late reproductive stage using fast chlorophyll fluorescence kinetic technology, in order to explore the effects of nitrogen on photosystem Ⅱ ( PS Ⅱ ) function of C4 photosynthetic gene transgenic rice flag leaves. The results showed that 1/4N treatment increased root length,decreased plant height,leaf area and chlorophyll contents of flag leaves in all cultivars, while 2N treatment increased leaf area and chlorophyll contents. C4 photosynthetic gene transgenic plants exposed to 1/4N treatment had higher chlorophyll contents, and PC had longest root length and largest leaf area of flag leaves, which indicated that they had more morphological advantage under 1/4N treatment than wild type. The fluorescence O-J-I-P curves changes were found in all cultivars under 1/4N treatment. The K phase (at 300 μs) increased and C

  6. Measurements of excited-state-to-excited-state transition probabilities and photoionization cross-sections using laser-induced fluorescence and photoionization signals

    International Nuclear Information System (INIS)

    Laser-induced photoionization and fluorescence signals were simultaneously observed in atomic samarium using Nd:YAG-pumped dye lasers. Two-color, three-photon photoionization and two-color fluorescence signals were recorded simultaneously as a function of the second-step laser power for two photoionization pathways. The density matrix formalism has been employed to analyze these signals. Two-color laser-induced fluorescence signal depends on the laser powers used for the first and second-step transitions as well as the first and second-step transition probability whereas two-color, three-photon photoionization signal depends on the third-step transition cross-section at the second-step laser wavelength along with the laser powers and transition probability for the first and second-step transitions. Two-color laser-induced fluorescence was used to measure the second-step transition probability. The second-step transition probability obtained was used to infer the photoionization cross-section. Thus, the methodology combining two-color, three-photon photoionization and two-color fluorescence signals in a single experiment has been established for the first time to measure the second-step transition probability as well as the photoionization cross-section. - Highlights: • Laser-induced photoionization and fluorescence signals have been simultaneously observed. • The density matrix formalism has been employed to analyze these signals. • Two-color laser-induced fluorescence was used to measure the second-step transition probability. • The second-step transition probability obtained was used to infer the photoionization cross-section. • Transition probability and photoionization cross-section have been measured in a single experiment

  7. Fluorescence/bioluminescence resonance energy transfer techniques to study G-protein-coupled receptor activation and signaling.

    Science.gov (United States)

    Lohse, Martin J; Nuber, Susanne; Hoffmann, Carsten

    2012-04-01

    Fluorescence and bioluminescence resonance energy transfer (FRET and BRET) techniques allow the sensitive monitoring of distances between two labels at the nanometer scale. Depending on the placement of the labels, this permits the analysis of conformational changes within a single protein (for example of a receptor) or the monitoring of protein-protein interactions (for example, between receptors and G-protein subunits). Over the past decade, numerous such techniques have been developed to monitor the activation and signaling of G-protein-coupled receptors (GPCRs) in both the purified, reconstituted state and in intact cells. These techniques span the entire spectrum from ligand binding to the receptors down to intracellular second messengers. They allow the determination and the visualization of signaling processes with high temporal and spatial resolution. With these techniques, it has been demonstrated that GPCR signals may show spatial and temporal patterning. In particular, evidence has been provided for spatial compartmentalization of GPCRs and their signals in intact cells and for distinct physiological consequences of such spatial patterning. We review here the FRET and BRET technologies that have been developed for G-protein-coupled receptors and their signaling proteins (G-proteins, effectors) and the concepts that result from such experiments. PMID:22407612

  8. Double-staining chromogenic in situ hybridization as a useful alternative to split-signal fluorescence in situ hybridization in lymphoma diagnostics

    DEFF Research Database (Denmark)

    van Rijk, A.; Svenstroup-Poulsen, T.; Jones, M.;

    2010-01-01

    , their detection is an important adjunct for increasing the reliability of the diagnosis. Recently, split-signal fluorescence hi situ hybridization has become available as a robust method to detect chromosomal breaks in paraffin-embedded formalin-fixed tissues. A bright field approach would bring this technology...... within the reach of every pathology laboratory. Design and Methods Our study was initiated to determine the consistency between chromogenic in situ hybridization and fluorescence in situ hybridization, both using split-signal probes developed for the detection of chromosomal breaks. Five hundred...... after split-signal fluorescence in situ hybridization staining. Conclusions We conclude that double-staining chromogenic in situ hybridization is equally reliable as fluorescence in situ hybridization in detecting chromosomal breaks in lymphoid tissue. Although differences in morphology, hematoxylin...

  9. Improved signal-to-noise ratio for non-perpendicular detection angles in x-ray fluorescence computed tomography (XFCT)

    Science.gov (United States)

    Sjölin, Martin; Danielsson, Mats

    2014-11-01

    The standard imaging setup in x-ray fluorescence computed tomography detects the fluorescence emission at a right angle with respect to the axis of the excitation beam. In this paper we have studied how the detection angle affects the signal-to-noise ratio (S/N), which is a major factor influencing the low-contrast sensitivity of the imaging system. This is done for an imaging setup using a collimated detector and a pencil beam of excitation x-rays. An ideal detection process is simulated for a generalized imaging case with gold/platinum tracers and experimental measurements are performed using a diagnostic x-ray tube. For monochromatic excitation, the results indicate that order-of-magnitude improvements of the S/N can be achieved by optimizing the detection angle. The maximal S/N, when exciting with an energy just above the K-edge, is achieved for large detection angles, i.e. with the detector close to the source. The improvements also transfer to polychromatic excitation sources and the experimental results show up to four-fold improvements of the S/N when changing the detection angle from 90° to 150°. Also, the changes of the S/N behavior when switching the fluorescent tracer is briefly demonstrated. These results suggest that the choice of detection angle should be taken seriously in the design of future XFCT imaging systems.

  10. Fluorescence detection of telomerase activity in cancer cell extracts based on autonomous exonuclease III-assisted isothermal cycling signal amplification.

    Science.gov (United States)

    Ding, Caifeng; Li, Xiaoqian; Wang, Wei; Chen, Yaoyao

    2016-09-15

    Based on the extension reaction of a telomerase substrate (TS) primer in the presence of the telomerase, strand-displacement process to perform more stable longer duplex chain, and stepwise hydrolysis of mononucleotides from the blunt or the recessed 3'-hydroxyl termini of duplex DNA in the presence of Exonuclease III (Exo III), an amplified fluorescence detection of telomerase activity in the cancer cells was described in this manuscript. A fluorescence probe DNA, a quencher DNA, and a TS primer were mixed to construct a three-chain DNA structure and a two-chain DNA structure because the amount of the TS primer was less than the other two DNA. In the presence of the telomerase, the quencher DNA was replaced from the probe DNA and the telomerase activity could be determined with the fluorescence enhancement. The telomerase activity in HeLa extracts equivalent to 6-2000 cells was detected by this method. Moreover, the strategy was further proved by using telomerase extracted from Romas cells. With the multiple rounds of isothermal strand displacement and the hydrolysis process, constituted consecutive of signal amplification for the novel detection paradigm that allowed measuring of telomerase activity in crude cancer cell extracts confirmed the reliability and practicality of the protocol, which reveal this platform holds great promise in the biochemical assay for the telomerase activity in early diagnosis for cancers. PMID:27108253

  11. Fluorescent detection of ATP based on signaling DNA aptamer attached silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yanyan; Wang Yusong; Liu Bin [Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117567 (Singapore)], E-mail: cheliub@nus.edu.sg

    2008-10-15

    Novel methods for rapid, sensitive and low-cost biomolecule detection have attracted particular interest because of their wide use in medical diagnostics, food inspection and biomedical research applications. In this work, we report a simple and efficient silica nanoparticle (NP)-based fluorescent assay for ATP detection. It takes advantage of the washing and separation properties of NPs and the structure-switch property of DNA aptamers, resulting in fluorescence change of the supernatant in the presence of targets. A linear response for ATP detection was observed from 0 to 6 mM with a detection limit of {approx}34 {mu}M. This detection strategy could be generalized to other aptamer-based detection systems.

  12. Laser-Induced Breakdown Spectroscopy and Chlorophyll a Flourescence Transients

    DEFF Research Database (Denmark)

    Frydenvang, Jens

    of a sufficient quality; something that remains a problem for many in-situ methods. In my PhD, I present my work with two such in-situ methods, Laser-Induced Breakdown Spectroscopy (LIBS) and OJIP transients, the rising part of chlorophyll a fluorescence transients from dark-adapted leaves....

  13. Mapping dynamic protein interactions in MAP kinase signaling using live-cell fluorescence fluctuation spectroscopy and imaging.

    Science.gov (United States)

    Slaughter, Brian D; Schwartz, Joel W; Li, Rong

    2007-12-18

    Fluorescence correlation spectroscopy (FCS), fluorescence cross-correlation spectroscopy (FCCS), and photon counting histograms (PCH) are fluctuation methods that emerged recently as potentially useful tools for obtaining parameters of molecular dynamics, interactions, and oligomerization in vivo. Here, we report the successful implementation of FCS, FCCS, and PCH in live yeast cells using fluorescent protein-tagged proteins expressed from their native chromosomal loci, examining cytosolic dynamics and interactions among components of the mitogen activated protein kinase (MAPK) cascade, a widely occurring signaling motif, in response to mating pheromone. FCS analysis detailed the diffusion characteristics and mobile concentrations of MAPK proteins. FCCS analysis using EGFP and mCherry-tagged protein pairs observed the interactions of Ste7 (MAPK kinase) with the MAPKs, Fus3 or Kss1, and of the scaffold protein, Ste5, with Ste7 and Ste11 (MAPK kinase kinase) in the cytosol, providing in vivo constants of their binding equilibrium. The interaction of Ste5 with Fus3 in the cytosol was below the limit of detection, suggesting a weak interaction, if it exists, with K(d) >400-500 nM. Using PCH, we show that cytosolic Ste5 were mostly monomers. Artificial dimerization of Ste5, as confirmed by PCH, using a dimerizing tag, stimulated the interaction between Ste5 and Fus3. Native Ste5 was found to bind Fus3 preferentially at the cortex in pheromone-treated cells, as detected by fluorescence resonance energy transfer (FRET). These results provide a quantitative spatial map of MAPK complexes in vivo and directly support the model that membrane association and regulation of the Ste5 scaffold are critical steps in MAPK activation. PMID:18077328

  14. Improved signal recognition for interphase fluorescent in-situ hybridization using a non-ionic detergent (NP-40) pretreatment

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, H.M.; Day-Salvatore, D.L.; Sciorra, L.J. [Univ. of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, NJ (United States)] [and others

    1994-09-01

    We have reported that the non-ionic detergent ethylphenolpoly (ethyleneglycolether)x known as Noniet-P40 (Shell International Petroleum) can gently disrupt cell membranes, resulting in cells with varying degrees of free chromatin release. The extent of this phenomena is dependent upon the concentration of NP-40 and the detergent`s exposure time to the cells. Treated cells can range from halos of DNA around the cells to fully extended free chromatin configurations. We have demonstrated that these treated cells are excellent targets for many different fluorescently labelled probes used for in situ hybridization studies. Recently, we have compared NP-40 harvested lymphocytes with normally harvested cells to see if we could improve upon the number of cells showing discreet signals in interphase fluorescent in situ hybridization. Preliminary work has shown that using a trisomy 21 cell line, one can get a statistically significant improvement with NP-40 pretreatment cells over control levels, in the number of cells having three discreet signals in interphase {open_quotes}FISH{close_quotes}. Such a pretreatment is simple to perform and may be of value when the number of cells available for analysis is low, as in the search for fetal cells from maternal circulation.

  15. Assessment of in vivo fluorescence method for chlorophyll-a estimation in optically complex waters (Curuai floodplain, Pará - Brazil Avaliação do método de fluorescência in vivo para a estimativa da concentração de clorofila-a em águas opticamente complexas (planície de inundação do Curuai, Pará - Brasil

    Directory of Open Access Journals (Sweden)

    Rafael Damiati Ferreira

    2012-12-01

    Full Text Available AIM: This paper describes an experiment carried out to evaluate in vivo fluorescence (IVF as an alternative method for chlorophyll-a estimation in optically complex aquatic environment (Amazon floodplain lakes METHODS: The experiment consisted of collecting in situ measurements at 26 sampling stations distributed throughout Curuai floodplain lakes. For each sampling station the following parameters were measured: temperature, turbidity, depth, Secchi depth, chlorophyll-a (Chl-a concentration, total suspended solids (TSS and dissolved organic carbon (DOC, concurrently with several transects of IVF. Two methods were tested for quantifying the fluorescence measurement to be used as input for the chlorophyll-a estimates: instantaneous IFV and average IVF. Global and regional models were tested and assessed by analyzing optically active components (Chl-a, DOC and TSS of the water. RESULTS: Regardless of fluorescence estimating method, the results indicate that it was not possible to fit a global model for estimating Chl-a from IVF for all the lakes in the Curuai floodplain. Regional models provided contrasting results according to the concentration of optically active components. The best results were observed for aquatic systems with a single dominant component homogenously distributed throughout the lake. The results highlight the influence of the ratios Chl-a/TSS, Chl-a/DOC and Phaephytin/Chl-a in the relationship between IVF and chlorophyll concentration. CONCLUSIONS: It was not possible to develop a global model to account for the entire region of Curuai floodplain. The search for regional models provided insights on the main factors affecting the relationship between IVF and Chl-a concentration. Nevertheless this work reinforces the great potential of fluorometry technique, since even with a small number of samples it was possible to set a good model in the main lake of the Curuai floodplain. In spite the fact that this is not an accurate

  16. Thousand-fold fluorescent signal amplification for mHealth diagnostics

    Science.gov (United States)

    The low sensitivity of Mobile Health (mHealth) optical detectors, such as those found on mobile phones, is a limiting factor for many mHealth clinical applications. To improve sensitivity, we have combined two approaches for optical signal amplification: (1) a computational approach based on an imag...

  17. Chlorophyll d: the puzzle resolved

    DEFF Research Database (Denmark)

    Larkum, Anthony W D; Kühl, Michael

    2005-01-01

    Chlorophyll a (Chl a) has always been regarded as the sole chlorophyll with a role in photochemical conversion in oxygen-evolving phototrophs, whereas chlorophyll d (Chl d), discovered in small quantities in red algae in 1943, was often regarded as an artefact of isolation. Now, as a result...... of discoveries over the past year, it has become clear that Chl d is the major chlorophyll of a free-living and widely distributed cyanobacterium that lives in light environments depleted in visible light and enhanced in infrared radiation. Moreover, Chl d not only has a light-harvesting role but might also...... replace Chl a in the special pair of chlorophylls in both reactions centers of photosynthesis. Udgivelsesdato: 2005-Aug...

  18. Resolution and signal-to-noise ratio improvement in confocal fluorescence microscopy using array detection and maximum-likelihood processing

    Science.gov (United States)

    Kakade, Rohan; Walker, John G.; Phillips, Andrew J.

    2016-08-01

    Confocal fluorescence microscopy (CFM) is widely used in biological sciences because of its enhanced 3D resolution that allows image sectioning and removal of out-of-focus blur. This is achieved by rejection of the light outside a detection pinhole in a plane confocal with the illuminated object. In this paper, an alternative detection arrangement is examined in which the entire detection/image plane is recorded using an array detector rather than a pinhole detector. Using this recorded data an attempt is then made to recover the object from the whole set of recorded photon array data; in this paper maximum-likelihood estimation has been applied. The recovered object estimates are shown (through computer simulation) to have good resolution, image sectioning and signal-to-noise ratio compared with conventional pinhole CFM images.

  19. Recognition- and Reactivity-Based Fluorescent Probes for Studying Transition Metal Signaling in Living Systems

    OpenAIRE

    Aron, Allegra T.; Ramos-Torres, Karla M.; Cotruvo, Joseph A.; Chang, Christopher J.

    2015-01-01

    Conspectus Metals are essential for life, playing critical roles in all aspects of the central dogma of biology (e.g., the transcription and translation of nucleic acids and synthesis of proteins). Redox-inactive alkali, alkaline earth, and transition metals such as sodium, potassium, calcium, and zinc are widely recognized as dynamic signals, whereas redox-active transition metals such as copper and iron are traditionally thought of as sequestered by protein ligands, including as static enzy...

  20. Análise dos transientes da fluorescência da clorofila a de plantas jovens de Carapa guianensis e de Dipteryx odorata submetidas a dois ambientes de luz Analysis of chlorophyll a fluorescence transients of young plants of Carapa guianensis and Dipteryx odorata submitted to two light environments

    Directory of Open Access Journals (Sweden)

    José Francisco de Carvalho Gonçalves

    2010-03-01

    odorata (Aublet Willd exposed to two light environments (shade and sunlight. The experiment was carried in Manaus-AM, Brazil (3º8'S, 59º52'W. Analysis of chlorophyll a fluorescence transients were obtained in intact and healthy leaves between 10:00 to 12:00 am. The curve OJIP indicated that the species high irradiance exposed presented photoinhibition after 45 days of experiment. Andiroba and cumaru plants exposed to sunlight exhibited low values of TRo/ABS (7.17 and 20.4%, respectively, ETo/TRo (14.5 and 27.2%, respectively and ETo/ABS (20.6 and 42.2%, respectively and high values of DIo/ABS (26.9 and 43.0%, respectively, compared with plants exposed to the shadow with 45 days of experiment. As for phenomenological flux, most of the parameters, low values were observed for both exposed species in the sunlight. Andiroba and cumaru plants exposed in the sunlight exhibited low values of PIABS (63.3 and 78.7%, respectively compared with exposed plants to the shadow at the end of the experiment. Although the species have suffered with the stress for high irradiance andiroba specie presented better performance than cumaru being indicated for use in production planting or degraded area restoration.

  1. Aggregation-induced emissive nanoparticles for fluorescence signaling in a low cost paper-based immunoassay.

    Science.gov (United States)

    Engels, Jan F; Roose, Jesse; Zhai, Demi Shuang; Yip, Ka Man; Lee, Mei Suet; Tang, Ben Zhong; Renneberg, Reinhard

    2016-07-01

    Low cost paper based immunoassays are receiving interest due to their fast performance and small amounts of biomolecules needed for developing an immunoassay complex. In this work aggregation-induced emissive (AIE) nanoparticles, obtained from a diastereoisomeric mixture of 1,2-di-(4-hydroxyphenyl)-1,2-diphenylethene (TPEDH) in a one-step top-down method, are characterized through Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM), and Zeta potential. By measuring the Zeta potential before and after labeling the nanoparticles with antibodies we demonstrate that the colloidal system is stable in a wide pH-range. The AIE-active nanoparticles are deposited on chitosan and glutaraldehyde modified paper pads overcoming the common aggregation-caused quenching (ACQ) effect. Analyte concentrations from 1000ng and below are applied in a model immunocomplex using Goat anti-Rabbit IgG and Rabbit IgG. In the range of 7.81ng-250ng, linear trends with a high R(2) are observed, which leads to a strong increase of the blue fluorescence from the TPEDH nanoparticles. PMID:27037781

  2. Structures of chlorophyll catabolites in bananas (Musa acuminata) reveal a split path of chlorophyll breakdown in a ripening fruit.

    Science.gov (United States)

    Moser, Simone; Müller, Thomas; Holzinger, Andreas; Lütz, Cornelius; Kräutler, Bernhard

    2012-08-27

    The disappearance of chlorophyll is a visual sign of fruit ripening. Yet, chlorophyll breakdown in fruit has hardly been explored; its non-green degradation products are largely unknown. Here we report the analysis and structure elucidation of colorless tetrapyrrolic chlorophyll breakdown products in commercially available, ripening bananas (Musa acuminata, Cavendish cultivar). In banana peels, chlorophyll catabolites were found in an unprecedented structural richness: a variety of new fluorescent chlorophyll catabolites (FCCs) and nonfluorescent chlorophyll catabolites (NCCs) were detected. As a rule, FCCs exist only "fleetingly" and are hard to observe. However, in bananas several of the FCCs (named Mc-FCCs) were persistent and carried an ester function at the propionate side-chain. NCCs were less abundant, and exhibited a free propionic acid group, but functional modifications elsewhere. The modifications of NCCs in banana peels were similar to those found in NCCs from senescent leaves. They are presumed to be introduced by enzymatic transformations at the stage of the mostly unobserved, direct FCC-precursors. The observed divergent functional group characteristics of the Mc-FCCs versus those of the Mc-NCCs indicated two major "late" processing lines of chlorophyll breakdown in ripening bananas. The "last common precursor" at the branching point to either the persistent FCCs, or towards the NCCs, was identified as a temporarily abundant "secondary" FCC. The existence of two "downstream" branches of chlorophyll breakdown in banana peels, and the striking accumulation of persistent Mc-FCCs call for attention as to the still-elusive biological roles of the resulting colorless linear tetrapyrroles.

  3. Tuning backbones and side-chains of cationic conjugated polymers for optical signal amplification of fluorescent DNA detection.

    Science.gov (United States)

    Huang, Yan-Qin; Liu, Xing-Fen; Fan, Qu-Li; Wang, Lihua; Song, Shiping; Wang, Lian-Hui; Fan, Chunhai; Huang, Wei

    2009-06-15

    Three cationic conjugated polymers (CCPs) exhibiting different backbone geometries and charge densities were used to investigate how their conjugated backbone and side chain properties, together with the transitions of DNA amphiphilic properties, interplay in the CCP/DNA-C* (DNA-C*: fluorophore-labeled DNA) complexes to influence the optical signal amplification of fluorescent DNA detection based on Förster resonance energy transfer (FRET). By examining the FRET efficiencies to dsDNA-C* (dsDNA: double-stranded DNA) and ssDNA-C* (ssDNA: single-stranded DNA) for each CCP, twisted conjugated backbones and higher charge densities were proved to facilitate electrostatic attraction in CCP/dsDNA-C* complexes, and induced improved sensitivity to DNA hybridization. Especially, by using the CCP with twisted conjugated backbone and the highest charge density, a more than 7-fold higher efficiency of FRET to dsDNA-C* was found than to ssDNA-C*, indicating a high signal amplification for discriminating between dsDNA and ssDNA. By contrast, linear conjugated backbones and lower charge density were demonstrated to favor hydrophobic interactions in CCP/ssDNA-C* complexes. These findings provided guidelines for the design of novel sensitive CCP, which can be useful to recognize many other important DNA activities involving transitions of DNA amphiphilic properties like DNA hybridization, such as specific DNA binding with ions, some secondary or tertiary structural changes of DNA, and so forth.

  4. Plant chlorophyll content meter

    Science.gov (United States)

    Spiering, Bruce A. (Inventor); Carter, Gregory A. (Inventor)

    2000-01-01

    A plant chlorophyll content meter is described which collects light reflected from a target plant and separates the collected light into two different wavelength bands. These wavelength bands, or channels, are described as having center wavelengths of 700 nm and 840 nm. The light collected in these two channels are processed using photo detectors and amplifiers. An analog to digital converter is described which provides a digital representation of the level of light collected by the lens and falling within the two channels. A controller provided in the meter device compares the level of light reflected from a target plant with a level of light detected from a light source, such as light reflected by a target having 100% reflectance, or transmitted through a diffusion receptor. The percent of reflection in the two separate wavelength bands from a target plant are compared to provide a ratio which indicates a relative level of plant physiological stress. A method of compensating for electronic drift is described where a sample is taken when a collection lens is covered to prevent light from entering the device. This compensation method allows for a more accurate reading by reducing error contributions due to electronic drift from environmental conditions at the location where a hand-held unit is used.

  5. EFFECTS OF SIMULATED ACID RAIN STRESS ON GAS EXCHANGE AND CHLOROPHYLL A FLUORESCENCE PARAMETERS IN LEAVES OF LONGAN%模拟酸雨对龙眼叶片气体交换和叶绿素a荧光参数的影响

    Institute of Scientific and Technical Information of China (English)

    邱栋梁; 刘星辉; 郭素枝

    2002-01-01

    Longan (Dimorcarpus longana Lour. cv. Wulongling) seedlings of two different ages grown in pots were selected to study the effects of acid rain stress on gas exchange, and chlorophyll a fluorescence parameters and their recovery. Sulfuric acid and nitric acid were selected for the preparation of artificial acid rain, based on the mole ratio 1:5 of sulfuric acid to nitric acid in the precipitation of southern Fujian. Dilution of reagent grade acid was done with distilled water and determined by Phsj-4 acidity analyzer. A series of solutions of simulated acid rains with pH 5.6, 3.0 and 2.5 were prepared. A sprayer was used to apply the acid solution to young trees. At each application, leaves were thoroughly wetted. Sprays were repeated 12 times in 6 h at 30 min intervals. Gas exchange was detected with an open gas analyzer CID-301PS, and chlorophyll a fluorescence parameters with OS5-FL modulated chlorophyll fluorometer.The results showed that photosynthesis was inhibited by acid rain stress, and light compensation point (LCP) of stressed leaves increased. Gas exchange and chlorophyll a fluorescence parameters of leaves were reduced after 6 h stress with acid rain of pH 3.0, and could be recovered to the level of control 72 h after the treatment ended. Net photosynthetic rate (Pn), stomatal conductance (Cs), transpiration rate (Tr), ratio of variable fluorescence to initial fluorescence (Fv/F0), ratio of variable fluorescence to maximum fluorescence (Fv/Fm), quantum yield of PSⅡelectron transport (ΦPSⅡ), ratio of fluorescence decrease (Rfd), nonphotochemical quenching (qN) and photochemical quenching (qP) were reduced after a 6 h stress with acid rain of pH 2.5, and could not be recovered 72 h after the stress ceased. Intercellular CO2 concentration (Ci) decreased under treatment with acid rain of pH 2.5, rose in the first day and surpassed the level of control 72 h after the acid rain spraying stopped. Dark respiration (Rd) was increased by acid rain, and

  6. 地面覆盖对苹果生育后期叶片叶绿素荧光动力学参数的影响%Effect of Ground-cover on Chlorophyll Fluorescence Kinetics of Apple Leaves at Late Growth Stage

    Institute of Scientific and Technical Information of China (English)

    张坤; 孙文泰; 马明

    2016-01-01

    The soil water thermal environment would different under different ground covers, to improve soil water thermal environment may influence the normal leaf senescence which delay nutrient re-flux, and reduce fruit quality. This study conducted in LongDong dry land orchards of the loess plateau, the chlorophyll fluorescence kinetics parameters of leaves under different covers are compared to support improvement and selection of ground-cover technology. The result shows that the relative variable fluorescence at J phase(2 ms) increased significantly, and at I phase(30 ms) which became consistent. At 300μs sites, point of K appeared clearly and chlorophyll fluorescence yield decreased than CK significantly of the different treatments. The ΔWoj, ΔWok values of CK are higher in K and L sites than other treatments. So, sand-cover treatment delayed leaf senescence or maintained the highest photosynthetic performance level during late growth stage, Although the photosynthetic performance level of grass-cover and film-mulch treatments higher than CK, but they are much lower than sand-cover treatment.%在黄土高原陇东旱地果园,比较了不同覆盖模式对苹果生育后期叶片叶绿素荧光动力学参数的影响,结果表明:叶绿素荧光诱导动力学曲线中的J相(2 ms)的相对可变荧光显著上升,在I相(30 ms)荧光强度趋于一致;不同处理在300μs左右的特征位点处,叶绿素荧光产量较清耕显著降低,出现明显K点; CK的ΔWoj、ΔWok值分别在K、 L位点升高。综合分析认为,果园覆沙延长叶片在生育后期维持高水平的光合性能或延迟叶片衰老时间,覆膜与覆草处理叶片光合性能水平比清耕高,但显著低于覆沙处理。

  7. Color change and chlorophyll fluorescence kinetics characteristics of Buxus microphylla leaves during the period of overwintering and regreening%越冬返青期间小叶黄杨叶色与叶绿素荧光动力学变化

    Institute of Scientific and Technical Information of China (English)

    彭金根; 刘燕; 郭翎; 高荣孚

    2011-01-01

    The Royal Horticultural Society Color Chart(RHSCC) and modulated chlorophyll fluorescence analysis technique were used in this paper to study the spatial and temporal color changes as well as chlorophyll fluorescence kinetics curve and parameters of leaves during the period of overwintering and regreening in three Buxus microphylla cultivars:'Green Beauty','Sunny Side' and 'Winter Green',which have been introduced from abroad to Beijing for more than ten years.The results indicated that sun leaf color of three cultivars of B.microphylla showed different levels of changes during the whole period.The color of 'Green Beauty' changed least,while 'Sunny Side' and 'Winter Green' showed serious discoloration.By contrast,shade leaf color of all cultivars almost presented no changes during the process.In addition,significant differences were observed in the chlorophyll fluorescence kinetics induction curve(FI) and the steady-state multistep fluorescence curve(SMS) from sun and shade leaves of three cultivars during periods of overwintering and regreening,and those differences were cultivars dependent.Before regreenning,sun leaves FI dynamics activity and fluctuations of SMS were significantly lower than those of shade leaves in the same period,and the recovery rate of the former was also slower than the latter during regreening.In winter,sun leaves of 'Green Beauty' maintained a certain activity of light and dark reactions and electrons transport rate,while 'Sunny Side' and 'Winter Green' were almost inactive.%利用英国皇家园艺学会比色卡(RHSCC)与调制式叶绿素荧光分析技术,研究了由国外引种北京10余年的3个小叶黄杨品种‘绿美’、‘阳光’及‘冬绿’的越冬及返青过程中叶色时空变化规律以及叶绿素荧光动力学曲线及参数。结果表明:3个品种阳生叶的叶色在整个过程中均有不同程度的变化,其中‘绿美’变化最小,‘阳

  8. Effects of Reduced Solar Radiation on Chlorophyll Fluorescence Parameters and Gas Exchange in Winter Wheat of Grain Filling Periods%太阳辐射减弱对冬小麦灌浆期叶绿素荧光及气体交换的影响

    Institute of Scientific and Technical Information of China (English)

    郑有飞; 倪艳利; 麦博儒; 冯妍; 孙健; 李健; 徐静馨

    2011-01-01

    In the recent years, global dimming of solar irradiance is growing due to the increase of aerosols, air pollutants and population density. In order to elucidate the effects of reduced solar irradiance on chlorophyll fluorescence parameters and gas exchange of winter wheat cultivar, we conducted a field experiment in Nanjing city by using the Triticum aestivum L. (cv.Yang mai 13) as the experimental plants. Five reduced solar radiation treatments were set up in the experiments, including 15%(T4), 20%(T3), 40%(T2), 60%(T1 )and 100%(CK)of natural solar radiation, while using Diving-PAM chlorophyll fluorometer and Lcpro+ photosynthesis to measured at different grain filling stages of crop chlorophyll fluorescence and gas exchange of the dynamic changes. The results showed that reducing solar radiation significantly increased chlorophyll and lutein content of winter wheat in the grain filling stage, but the Chla/Chlb and photosynthetic rate( Pn) continued to decrease. Fv/Fm, qP, Y( NO), ( 1 -qP)INPQ and the actual photochemical efficiency(Yield) increased with solar radiation intensity decreased, and show a downward trend, but NPQ, Y (NPQ) and L (PFD) rised. Visible, less solar radiationis cut in winter wheat leaves, when the primary photochemical reaction of PS II electron transfers efficiency met the energy shortage of stress( a decline in photochemical quenching qP). Meanwhile, reducing the electronic delivery of the body (PQ) activity (quantum efficiency Yield was lower), was to increase the heat dissipation leaves, resulting in reduced photosynthetic capacity.%以冬小麦为供试材料,在大用试验条件下研究了模拟太阳辐射减弱对冬小麦旗叶光合色素、叶绿素荧光参数及气体交换的影响.试验中设计了15%、20% 、40% 、60%和100%(CK)自然太阳总辐射5种太阳总辐射处理,同时采用Diving-PAM叶绿素荧光仪和LCpro+光合仪测定了不同灌浆阶段作物叶绿素荧光及气体交换参数的动态

  9. Validation of MODIS FLH and In Situ Chlorophyll a from Tampa Bay, Florida (USA)

    Science.gov (United States)

    Fischer, Andrew; MorenoMadrinan, Max J.

    2012-01-01

    Satellite observation of phytoplankton concentration or chlorophyll-a (chla) is an important characteristic, critically integral to monitoring coastal water quality. However, the optical properties of estuarine and coastal waters are highly variable and complex and pose a great challenge for accurate analysis. Constituents such as suspended solids and dissolved organic matter and the overlapping and uncorrelated absorptions in the blue region of the spectrum renders the blue-green ratio algorithms for estimating chl-a inaccurate. Measurement of suninduced chlorophyll fluorescence, on the other hand, which utilizes the near infrared portion of the electromagnetic spectrum may, provide a better estimate of phytoplankton concentrations. While modelling and laboratory studies have illustrated both the utility and limitations of satellite algorithms based on the sun induced chlorophyll fluorescence signal, few have examined the empirical validity of these algorithms or compared their accuracy against bluegreen ratio algorithms . In an unprecedented analysis using a long term (2003-2011) in situ monitoring data set from Tampa Bay, Florida (USA), we assess the validity of the FLH product from the Moderate Resolution Imaging Spectrometer against a suite of water quality parameters taken in a variety of conditions throughout this large optically complex estuarine system. . Overall, the results show a 106% increase in the validity of chla concentration estimation using FLH over the standard chla estimate from the blue-green OC3M algorithm. Additionally, a systematic analysis of sampling sites throughout the bay is undertaken to understand how the FLH product responds to varying conditions in the estuary and correlations are conducted to see how the relationships between satellite FLH and in situ chlorophyll-a change with depth, distance from shore, from structures like bridges, and nutrient concentrations and turbidity. Such analysis illustrates that the correlations between

  10. Construction of fluorescence resonance energy transfer vectors and their application in study of structure and function of signal transducers and activators of transcription 1

    Institute of Scientific and Technical Information of China (English)

    Fujun Han; Yongfeng Luo; Nanhai Ge; Jun Xu

    2008-01-01

    Protein-protein interactions have been studied extensively by green fluorescent protein-based fluorescence resonance energy transfer (FRET). The fluorescent proteins (FP) can be fused either to the N- or C-terminus of a host protein, but it is difficult to predict which order will perturb the host protein the least and provide the largest FRET. Therefore, a researcher needs to fuse host proteins with FP at both the N- and C-termini and test every possible combination (N-N,N-C, or C-C) to promote the energy transfer efficiency.Consequently, researchers required to do many subelonings.Herein, we designed FRET vectors to make them more efficient. The expression vectors ofpCTP.YFP and pYFP-CFP were constructed with both cyan fluorescent protein (CFP)-yellow fluorescent protein (YFP) and YFP-CFP coding sequences flanked by two restriction enzyme sites, and with multiple cloning regions in the middle of both coding sequences. To select an optimal combination for FRET detection, we created plasmids encoding various fusion proteins of FP and signal transducers and activators of transcription 1 (STAT1). We found that the nuclear:cytoplasmic fluorescence intensity ratios of STAT1 -FP were significantly higher than those of FP-STAT1 at steady state,and fluorescence redistribution was only observed for STAT1-FP upon interferon gamma (IFNΥ) stimulation. In addition, positive FRET signals were only detected in the C-C interactions of STAT 1 homodimer. Taken together, these data indicate that fusing STATI at the N.terminus with Fpimpairs the interactions ofunphospborylated STAT1 homodimers and possibly diminishes its binding with DNA. In contrast, STATIFP was functional with respect to its activation. Moreover, the FRET vectors are able to facilitate FRET studies.

  11. The Application of Variable Chlorophyll Fluorescenceto Microphytobenthic Biofilms

    OpenAIRE

    Perkins, Rupert G.; Kromkamp, Jacco C.; Serôdio, Joao; Lavaud, Johann; Jesus, Bruno; Mouget, Jean-Luc; Lefebvre, Sébastien; Forster, R. M.

    2010-01-01

    Community assemblages of diatoms, green algae andcyanobacteria comprise the microphytobenthos (MPB),which inhabit benthic sediment ecosystems (Admiraal1984; Underwood and Kromkamp 1999; Consalvey et al. 2004). Particular attention has been paid to theanalysis of intertidal soft sediment systems, e.g. cohesivemudflat and sandy substrata typical of estuarine habitats.Variable chlorophyll fluorescence has been applied tothese systems since the 1990s, in an attempt to investigatethe primary produ...

  12. Near-infrared fluorescence imaging of cancer mediated by tumor hypoxia and HIF1α/OATPs signaling axis

    Science.gov (United States)

    Wu, Jason Boyang; Shao, Chen; Li, Xiangyan; Shi, Changhong; Li, Qinlong; Hu, Peizhen; Chen, Yi-Ting; Dou, Xiaoliang; Sahu, Divya; Li, Wei; Harada, Hiroshi; Zhang, Yi; Wang, Ruoxiang; Zhau, Haiyen E.; Chung, Leland W.K.

    2014-01-01

    Near-infrared fluorescence (NIRF) imaging agents are promising tools for noninvasive cancer imaging. Here, we explored the mechanistic properties of a specific group of NIR heptamethine carbocyanines including MHI-148 dye we identified and synthesized, and demonstrated these dyes to achieve cancer-specific imaging and targeting via a hypoxia-mediated mechanism. We found that cancer cells and tumor xenografts exhibited hypoxia-dependent MHI-148 dye uptake in vitro and in vivo, which was directly mediated by hypoxia-inducible factor 1α (HIF1α). Microarray analysis and dye uptake assay further revealed a group of hypoxia-inducible organic anion-transporting polypeptides (OATPs) responsible for dye uptake, and the correlation between OATPs and HIF1α was manifested in progressive clinical cancer specimens. Finally, we demonstrated increased uptake of MHI-148 dye in situ in perfused clinical tumor samples with activated HIF1α/OATPs signaling. Our results establish these NIRF dyes as potential tumor hypoxia-dependent cancer-targeting agents and provide a mechanistic rationale for continued development of NIRF imaging agents for improved cancer detection, prognosis and therapy. PMID:24957295

  13. Near-infrared fluorescence imaging of cancer mediated by tumor hypoxia and HIF1α/OATPs signaling axis.

    Science.gov (United States)

    Wu, Jason Boyang; Shao, Chen; Li, Xiangyan; Shi, Changhong; Li, Qinlong; Hu, Peizhen; Chen, Yi-Ting; Dou, Xiaoliang; Sahu, Divya; Li, Wei; Harada, Hiroshi; Zhang, Yi; Wang, Ruoxiang; Zhau, Haiyen E; Chung, Leland W K

    2014-09-01

    Near-infrared fluorescence (NIRF) imaging agents are promising tools for noninvasive cancer imaging. Here, we explored the mechanistic properties of a specific group of NIR heptamethine carbocyanines including MHI-148 dye we identified and synthesized, and demonstrated these dyes to achieve cancer-specific imaging and targeting via a hypoxia-mediated mechanism. We found that cancer cells and tumor xenografts exhibited hypoxia-dependent MHI-148 dye uptake in vitro and in vivo, which was directly mediated by hypoxia-inducible factor 1α (HIF1α). Microarray analysis and dye uptake assay further revealed a group of hypoxia-inducible organic anion-transporting polypeptides (OATPs) responsible for dye uptake, and the correlation between OATPs and HIF1α was manifested in progressive clinical cancer specimens. Finally, we demonstrated increased uptake of MHI-148 dye in situ in perfused clinical tumor samples with activated HIF1α/OATPs signaling. Our results establish these NIRF dyes as potential tumor hypoxia-dependent cancer-targeting agents and provide a mechanistic rationale for continued development of NIRF imaging agents for improved cancer detection, prognosis and therapy.

  14. Exploring 1,4-dihydroxyanthraquinone as long-range emissive ratiometric fluorescent probe for signaling Zn(2+)/PO4(3-): Ensemble utilization for live cell imaging.

    Science.gov (United States)

    Sinha, Sougata; Gaur, Pankaj; Mukherjee, Trinetra; Mukhopadhyay, Subhrakanti; Ghosh, Subrata

    2015-07-01

    Fluorescent 1,4-dihydroxyanthraquinone 1 was found to demonstrate its ratiometric signaling property upon interaction with divalent zinc (Zn(2+)). While the probe itself exhibited fluorescence emission in the yellow region (λem=544 nm and 567 nm), binding with Zn(2+) induced strong emission in the orange region (λem=600 nm) which was mainly due to a combination of CHEF and ICT mechanism. The probe was found to be highly sensitive toward the detection of zinc and the limit of detection (LOD) was calculated to be 9×10(-7) M. The possibility of using this probe for real-time analysis was strongly supported by the striking stability of fluorescence signal for more than five days with similar fluorescence intensity as observed during instant signaling. The present probe works within physiological pH range and is devoid of any interference caused by the same group elements such as Cd(2+)/Hg(2+). The probe possesses excellent excitation/emission wavelength profile and can penetrate cell membrane to image low concentration of zing inside living system. The in situ formed zinc-probe ensemble was further explored as ratiometric sensing platform for detecting another bio-relevant analyte phosphate anion through a zinc-displacement approach.

  15. Effects of magnesium on chlorophyll fluorescence and active oxygen scavenging system of fruiting-node leaves of muskmelon%镁对厚皮甜瓜坐果节位叶片叶绿素荧光特性和活性氧清除系统的影响

    Institute of Scientific and Technical Information of China (English)

    朱立保; 刘海河; 张彦萍; 张利云; 王正

    2015-01-01

    [Objectives] Muskmelon leaves are often premature senescent at the fruit ripening stage, especially the leaves located on the fruiting-node, seriously decreasing the functions of photosynthetic system and fruit growth. The effects of magnesium on improving function of chlorophyll fluorescence and active oxygen scavenging system were studied. [Methods] Muskmelon cultivar‘Yingchun( F1 ) ’ was used as test material and sprayed with MgSO4 solution of 0 , 2 , 4 and 6 mmol/L on the day when female flowers on fruiting-nodes were opening and being hand-pollinated. The sprays were made once a week and 3 sprays in all. Every other week, the physiological indexes of leaves on fruiting-nodes were determined after the first spray. The chlorophyll fluorescence and photosynthesischaracteristics were measured using imaging fluorescence spectrometer MINI-IMAGING-PAM and portable photosynthesis system Li-6400, the leaf Mg content by ICP-OES method, and the enzyme activities and the contents of malondialdehyde( MDA) , soluble sugar and soluble protein in the fruits were measured referring to the LI He-sheng’s experiment method, the soluble solids with a handheld sugar meter, and the Vc content by 2, 6-dichloro phenol indophenol titration method. [Results] From analyzing physiological indexes of leaves on fruiting-nodes and fruits, the following results can be obtained: the spray of 2 mmol/L and 4 mmol/L Mg2+ could significantly increase the Mg levels in fruiting-node leaves, and delay the degradation rate of chlorophyll during the process of leaf senescence at the same time. Some chlorophyll fluorescence and photosynthesis characteristic parameters, including the maximal photochemical efficiency(Fv/Fm), quantum yield of PSII electron transport (ФPSⅡ) , apparent electron transport rate( ETR) and net photosynthetic rate are promoted at various degrees under the 2 mmol/L and 4 mmol/L Mg2+treatments, while the minimal fluorescence( Fo) is decreased dramatically. The antioxidant

  16. Chlorophyll catabolism in olive fruits (var. Arbequina and Hojiblanca) during maturation.

    Science.gov (United States)

    Vergara-Domínguez, Honorio; Ríos, José Julían; Gandul-Rojas, Beatriz; Roca, María

    2016-12-01

    The central reaction of chlorophyll (chl) breakdown pathway occurring during olive fruits maturation is the cleavage of the macrocycle pheophorbide a to a primary fluorescent chl catabolite (pFCC) and it is catalyzed by two enzymes: pheophorbide a oxygenase (PaO) and red chl catabolite reductase (RCCR). In subsequent steps, pFCC is converted to different fluorescent chlorophyll catabolites (FCCs) and nonfluorescent chlorophyll catabolites (NCCs). This work demonstrated that RCCR activity of olive fruits is type II. During the study of evolution of PaO and RCCR activities through the olive fruits maturation in two varieties: Hojiblanca and Arbequina, a significant increase in PaO and RCCR activity was found in ripening stage. In addition, the profile and structure of NCCs present in epicarp of this fruit was studied using HPLC/ESI-TOF-MS. Five different NCCs were defined and for the first time the enzymatic reactions implied in chlorophyll degradations in olive fruits elucidated. PMID:27374574

  17. Design of a Real-time Signal Processing System for LIF Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Xiande; Zheng Wengang; Dong Daming; Shen Changjun; Zhang Xin; Zhou Jianjun; Yan Hua; Wu Wenbiao, E-mail: zhengwg@nercita.org.cn [National Engineering Research Center for Information Technology in Agriculture, 100097 (China)

    2011-02-01

    Laser Induced Fluorescence (LIF) sensor is one of the most sensitive approaches available for a variety of analytical applications, such as determination of nitrogen content of plant leaves, detection of chlorophyll content in water, etal. As a core instrumental requirements of real time LIF sensor, signal processing system is used to store effective processing and identification algorithms in a short time. By analyzing the working principle of LIF sensor in detail, a novel platform of signal processing system used in LIF sensor is proposed in this paper. The design solutions and hardware architecture of the system are described in this paper, include Digital Signal Processor (DSP), data transmission block, and memory block. Several steps of signal processing methods are proposed, according to the characteristic of LIF sensor. At last, an application of using the signal processing system designed in this paper for measuring chlorophyll content in plant leaves is shown.

  18. Effects of nitrogen regulation on photosystem Ⅱ chlorophyll fluorescence characteristics of functional leaves in sugar beet (Beta vulgaris) under salt environment%氮调控对盐环境下甜菜功能叶光系统Ⅱ荧光特性的影响

    Institute of Scientific and Technical Information of China (English)

    尹海龙; 田长彦

    2013-01-01

    采用盆栽试验方法,以NaCl为盐分模拟不同盐度环境,研究了施氮(N)对盐环境下生长的甜菜(Beta vulgaris)功能叶光系统Ⅱ (PSⅡ)荧光特性的影响及光合色素含量的变化.结果表明:在轻度、中度及重度盐环境下,施N均能增大PSⅡ最大光化学效率(Fv/Fm)、PSⅡ潜在活性(Fv/Fo)、PSⅡ实际光量子产量(Y(Ⅱ))、非调节性能量耗散的量子产量(Y(NO))、相对电子传递速率(ETR)及光化学猝灭系数(qp),且在适宜的施N范围内(0-1.2 g·kg-1)上述参数随施N量的增加而增大.各叶绿素荧光参数光响应的结果表明,随着光强的增加,各处理下调节性能量耗散的量子产量(KNPQ))、ETR及非光化学猝灭系数(NPQ)旱上升趋势,相反,Y(Ⅱ)、Y(NO)及qp则呈下降趋势,在有效的光强范围内(0-1 000 μmol·m-2·s-1)施N提高了甜菜功能叶PSⅡ反应中心的开放程度,并且在高光强下调节PSⅡ耗散掉过剩的光能以避免对其反应中心造成伤害.各盐度环境下施N也显著增加了甜菜功能叶叶绿素与类胡萝卜素含量,增大了叶绿素a/叶绿素b值,且叶绿素与类胡萝卜素含量随施N水平的增加而增加.说明盐环境下施N能够增强甜菜功能叶PSⅡ的活性,提高PSⅡ光能利用率,从而增强其对盐渍环境的适应性.%Aims Our objective was to determine the effects of nitrogen regulation on photosystem Ⅱ (PSII) chlorophyll fluorescence of functional leaves in sugar beet (Beta vulgaris) under salt environment. Methods Using potted sugar beet plants, different salt environments were produced with NaCl; nitrogen was produced with NH4NO3. Important findings Maximal PSII quantum yield (Fv/Fm), and latent PSII quantum yield (Fv/Fo), effective PSII quantum yield (Y(II)), quantum yield of non-regulated energy dissipation (7(N0)), electron transport rate (ETR) and coefficient of photochemical quenching (qP) were increased by nitrogen application under mild, moderate and high salt

  19. Alzheimer’s disease diagnosis by detecting exogenous fluorescent signal of ligand bound to beta amyloid in the lens of human eye: an exploratory study

    Directory of Open Access Journals (Sweden)

    Charles eKerbage

    2013-05-01

    Full Text Available We report results of a clinical exploratory human trial involving 10 participants using a combination of a fluorescent ligand and a laser scanning device, SAPPHIRE System, as an aid in the diagnosis of Probable Alzheimer’s disease (AD. To the best of our knowledge, this is the first time that such a technique has been used in vivo of a human lens. The primary goal of the clinical trial, in addition to safety assessment, was to evaluate efficacy of the system. By detecting specific fluorescent signature of ligand bound beta amyloid in the supranucleus region of the human lens, a two-fold differentiation factor between AD patients and Control groups is achieved. Data from our studies indicates that deeper regions of the supranucleus provide the highest measures of ligand bound fluorescence signal from both controls and AD patients. Further studies are underway involving a larger population for statistical evaluation of the method.

  20. Design of a dual-signaling sensing system for fluorescent ratiometric detection of Al3+ ion based on the inner-filter effect.

    Science.gov (United States)

    Wang, Yongxiang; Xiong, Limin; Geng, Fenghua; Zhang, Fuqiang; Xu, Maotian

    2011-11-21

    A dual-signal sensing system based on the inner-filter effect (IFE) was demonstrated, in which the combination of two signaling mechanisms allows metal binding to turn on two fluorescence emission bands, independently. A proof-of-concept fluorescent ratiometric assay for Al(3+) in pure aqueous solution is presented. The proposed assay is based on the Al(3+)-induced color and fluorescence changes of Alizarin red S (ARS) and IFE between ARS and meso-tetra(N-methyl-4-pyridyl)porphine tetratosylate salt (TMPyP). In the absence of Al(3+), the absorption spectrum of the ARS in 0.2 M HAc-NaAc buffer (pH 5.5) has a strong peak at 420 nm, significantly overlapping with the excitation of TMPyP. ARS is expected to be capable of functioning as a powerful absorber to tune the emission of TMPyP on account of the spectral overlap. Binding of Al(3+) with ARS forms a fluorometric ARS/Al(3+) complex and shifts the maximum absorbance from 420 nm to 480 nm, which overlaps negligibly with the excitation of TMPyP and turns on the proper emission spectrum for TMPyP. Under the optimum conditions, The fluorescence intensity ratio, F(585)/F(651), responds to Al(3+) over a dynamic range of 0.1-1.5 μM, with a limit of detection of 40 nM, where F(585) and F(651) are the fluorescence intensity at 585 nm and 651 nm in the absence or presence of Al(3+), respectively. Further application in Al(3+)-spiked water samples suggested a recovery between 95 and 108%. The fluorescence response is highly selective for Al(3+) over other metal ions with the addition of thiourea as the masking agent.

  1. Investigating the Control of Chlorophyll Degradation by Genomic Correlation Mining.

    Science.gov (United States)

    Ghandchi, Frederick P; Caetano-Anolles, Gustavo; Clough, Steven J; Ort, Donald R

    2016-01-01

    Chlorophyll degradation is an intricate process that is critical in a variety of plant tissues at different times during the plant life cycle. Many of the photoactive chlorophyll degradation intermediates are exceptionally cytotoxic necessitating that the pathway be carefully coordinated and regulated. The primary regulatory step in the chlorophyll degradation pathway involves the enzyme pheophorbide a oxygenase (PAO), which oxidizes the chlorophyll intermediate pheophorbide a, that is eventually converted to non-fluorescent chlorophyll catabolites. There is evidence that PAO is differentially regulated across different environmental and developmental conditions with both transcriptional and post-transcriptional components, but the involved regulatory elements are uncertain or unknown. We hypothesized that transcription factors modulate PAO expression across different environmental conditions, such as cold and drought, as well as during developmental transitions to leaf senescence and maturation of green seeds. To test these hypotheses, several sets of Arabidopsis genomic and bioinformatic experiments were investigated and re-analyzed using computational approaches. PAO expression was compared across varied environmental conditions in the three separate datasets using regression modeling and correlation mining to identify gene elements co-expressed with PAO. Their functions were investigated as candidate upstream transcription factors or other regulatory elements that may regulate PAO expression. PAO transcript expression was found to be significantly up-regulated in warm conditions, during leaf senescence, and in drought conditions, and in all three conditions significantly positively correlated with expression of transcription factor Arabidopsis thaliana activating factor 1 (ATAF1), suggesting that ATAF1 is triggered in the plant response to these processes or abiotic stresses and in result up-regulates PAO expression. The proposed regulatory network includes the

  2. Optical Reflectance and Fluorescence for Detecting Nitrogen Needs in Zea mays L.

    Science.gov (United States)

    McMurtrey, J. E.; Middleton, E. M.; Corp. L. A.; Campbell, P. K. Entcheva; Butcher, L. M.; Daughtry, C. S. T.

    2003-01-01

    Nitrogen (N) status in field grown corn (Zea mays L.) was assessed using spectral techniques. Passive reflectance remote sensing and, both passive and active fluorescence sensing methods were investigated. Reflectance and fluorescence methods are reported to detect changes in the primary plant pigments (chlorophylls a and b; carotenoids) in higher plant species. As a general rule, foliar chlorophyll a (Chl a) and chlorophyll b (Chl b) usually exist in approx.3:l ratio. In plants under stress, Chl b content is affected before Chl a reductions occur. For reflectance, a version of the chlorophyll absorption in reflectance index (CARI) method was tested with narrow bands from the Airborne Imaging Spectroradiometer for Applications (ASIA). CARI minimizes the effects of soil background on the signal from green canopies. A modified CARI (MCARI) was used to track total Chl a levels in the red dip of the spectrum from the corn canopy. A second MCARI was used to track the auxiliary plant pigments (Chl b and the carotenoids) in the yellow/orange/red edge part of the reflectance spectrum. The difference between these two MCARI indices detected variations in N levels across the field plot canopies using ASIA data. At the leaf level, ratios of fluorescence emissions in the blue, green, red and far-red wavelengths sensed responses that were associated with the plant pigments, and were indicative of energy transfer in the photosynthetic process. N stressed corn stands could be distinguish from those with optimally applied N with fluorescence emission spectra obtained from individual corn leaves. Both reflectance and fluorescence methods are sensitive in detecting corn N needs and may be especially powerful in monitoring crop conditions if both types of information can be combined.

  3. A novel label-free fluorescence strategy for methyltransferase activity assay based on dsDNA-templated copper nanoparticles coupled with an endonuclease-assisted signal transduction system.

    Science.gov (United States)

    Lai, Q Q; Liu, M D; Gu, C C; Nie, H G; Xu, X J; Li, Z H; Yang, Z; Huang, S M

    2016-02-21

    Evaluating DNA methyltransferase (MTase) activity has received considerable attention due to its significance in the fields of early cancer clinical diagnostics and drug discovery. Herein, we proposed a novel label-free fluorescence method for MTase activity assay by coupling double-stranded DNA (dsDNA)-templated copper nanoparticles (CuNPs) with an endonuclease-assisted signal transduction system. In this strategy, dsDNA molecules were first methylated by DNA adenine methylation (Dam) MTase and then cleaved by the methylation-sensitive restriction endonuclease DpnI. The cleaved DNA fragments could not act as efficient templates for the formation of fluorescent CuNPs and thus no fluorescence signal was produced. Under optimized experimental conditions, the developed strategy exhibited a sensitive fluorescence response to Dam MTase activity. This strategy was also demonstrated to provide an excellent platform to the inhibitor screening for Dam MTase. These results demonstrated the great potential for the practical applications of the proposed strategy for Dam MTase activity assay. PMID:26764536

  4. Study on the Correlation Between Chlorophyll Maximum and Remote Sensing Data

    Institute of Scientific and Technical Information of China (English)

    XIU Peng; LIU Yuguang

    2006-01-01

    Based on the in situ optical measurements in the Bohai Sea of China, which belongs to a typical case-2 water area, we studied the characteristics of DCM (deep chlorophyll maximum) such as its spatial distribution, vertical profile,etc.We found that when the depth of the chlorophyll maximum is comparatively small, even in turbid coastal water regions,there is always a good correlation between the concentrations of chlorophyll maximum and the satellite-received signals in blue-green spectral bands; the correlation is even better than that between the surface chlorophyll concentrations and the satellite-received signals.The strong correlation existing even in turbid coastal water regions indicates that an ocean color model to retrieve the concentration of DCM can be constructed for coastal waters if a comprehensive knowledge of the vertical distribution of chlorophyll concentration in the Bohai Sea of China is available.

  5. Effects of Water Stress on Photochemical Quenching and Non-photochemical Quenching of Chlorophyll a Fluorescence in Four Tree Seedlings%水分胁迫对4种苗木叶绿素荧光的光化学淬灭和非光化学淬灭的影响

    Institute of Scientific and Technical Information of China (English)

    史胜青; 袁玉欣; 杨敏生; 梁海永; 张金香

    2004-01-01

    The changes of photochemical quenching(qp) and non-photochemical quenching(qN) of chlorophyll a fluorescence in leaves of four tree seedlings ( Gleditsia sinensis, Juglans regia, Diospyros kaki and Diospyros lotus ) were different between two different water stress ways:detached drought treatment and potted drought treatment. After 4 hours dehydration by leaf detaching,the qp values had significant decrease except J. regia, only 6 hours later, the qp values compared with contrast decreased significantly in four tree seedlings(P>0.05), but the range of reduction( G.sinensis, J.regia and D.lotus) was just 2.5% to 6.4%. D.kaki, however,got to 31.3%. While the qN values increased significantly with conducting dehydration of the detached leaves. However, the qp values of four species showed no significant decrease when they were growing in pots under soil water stress(40%~60% RWC) for 30 days; and the qN values decreased obviously with a exception in J. regia, which was consistent with that of detached leaf treatment. The results suggested that some difference or changes in mechanism of excess light energy dissipation might perform in four seedlings by short-term and long-term water stress.

  6. A unique "turn-on" fluorescence signalling strategy for highly specific detection of ascorbic acid using carbon dots as sensing probe.

    Science.gov (United States)

    Fong, Jessica Fung Yee; Chin, Suk Fun; Ng, Sing Muk

    2016-11-15

    Carbon dots (CDs) that showed strong blue fluorescence were successfully synthesised from sodium alginate via furnace pyrolysis. The single step pyrolytic synthesis was simple to perform while yielded CDs with high photostability, good water solubility and minimum by-products. In order to design the probe with "turn-on" sensing capability, the CDs were screened against a series of metal cations to first "turn-off" the fluorescence. It was found that ferric ions (Fe(3+)) were most responsive and effective in quenching the fluorescence of CDs. Based on this observation, the conditioning of the probe was performed to ensure the fluorescence was completely quenched, while not overloading the system with Fe(3+). At the optimised condition, the CDs-Fe(3+) mixture served as a highly specific detection probe for ascorbic acid (AA). The analytical potential of the probe was evaluated and showed a good linear range of response for AA concentration of 24-40μg/mL. The selectivity study against other possible co-existing species was carried out and proved that our unique "turn-on" fluorescence signalling strategy was highly effective and selective towards AA as the target analyte. The probe was demonstrated for quantification of AA in real samples, which was the commercially available vitamin C supplement. The result showed good accuracy with minimum deviation from standard method adopted for validation purpose. PMID:27290666

  7. A Graphene Oxide-Based Sensing Platform for the Determination of Methicillin-Resistant Staphylococcus aureus Based on Strand-Displacement Polymerization Recycling and Synchronous Fluorescent Signal Amplification.

    Science.gov (United States)

    Ning, Yi; Gao, Qiang; Zhang, Xiaoqing; Wei, Ke; Chen, Lingli

    2016-09-01

    To develop new technology for detecting methicillin-resistant Staphylococcus aureus (MRSA), a novel fluorescent biosensor based on Klenow fragment (KF)-assisted target recycling amplification and synchronous fluorescence analysis was created. Carboxy-fluorescein (FAM)-labeled single-stranded DNA (ssDNA) containing a capture probe and a signal probe was adsorbed onto the surface of graphene oxide (GO) via π-stacking interactions, resulting in the fluorescence quenching of the dye. When target and primer were introduced, the fluorescence was restored due to P0 being completely released from the surface of the GO. Meanwhile, by using the KF and exploiting the synergistic effect of FAM and the double-stranded DNA (dsDNA)-SYBR Green I duplex structure, the fluorescence in this detection system was considerably amplified and the sensitivity was improved. The proposed strategy for mecA gene analysis showed a good linear range from 1 to 40 nmol/L, with a lower limit of detection of 0.5 nmol/L. In addition, a bacterial sample harboring the mecA gene was also detected, and its lower detection limit was up to 300 colony-forming units (CFU)/mL. Accordingly, this biosensor exhibits high sensitivity and selectivity and has great potential for early clinical diagnosis and treatment. PMID:27286718

  8. Viral Preprotoxin Signal Sequence Allows Efficient Secretion of Green Fluorescent Protein by Candida glabrata, Pichia pastoris, Saccharomyces cerevisiae, and Schizosaccharomyces pombe

    OpenAIRE

    Eiden-Plach, Antje; Zagorc, Tatjana; Heintel, Tanja; Carius, Yvonne; Breinig, Frank; Manfred J Schmitt

    2004-01-01

    Besides its importance as model organism in eukaryotic cell biology, yeast species have also developed into an attractive host for the expression, processing, and secretion of recombinant proteins. Here we investigated foreign protein secretion in four distantly related yeasts (Candida glabrata, Pichia pastoris, Saccharomyces cerevisiae, and Schizosaccharomyces pombe) by using green fluorescent protein (GFP) as a reporter and a viral secretion signal sequence derived from the K28 preprotoxin ...

  9. Double-staining chromogenic in situ hybridization as a useful alternative to split-signal fluorescence in situ hybridization in lymphoma diagnostics

    OpenAIRE

    Rijk, A.; Svenstroup-Poulsen, T.; Jones, M.(Purdue University, West Lafayette, U.S.A.); Cabecadas, J.; Cigudosa, J. C.; Leoncini, L.; Mottok, A; Bergman, C.C.; Pouliou, E.; Dutoit, S H; van Krieken, J H J M

    2009-01-01

    BACKGROUND: Malignant lymphomas are classified based on morphology, immunophenotype, genetics and clinical features. The pathological diagnosis is generally considered difficult and prone to mistakes. Since non-random chromosomal translocations are specifically involved in specific entities, their detection is an important adjunct for increasing the reliability of the diagnosis. Recently, split-signal fluorescence in situ hybridization has become available as a robust method to detect chromos...

  10. Chlorophylls, Symmetry, Chirality, and Photosynthesis

    Directory of Open Access Journals (Sweden)

    Mathias O. Senge

    2014-09-01

    Full Text Available Chlorophylls are a fundamental class of tetrapyrroles and function as the central reaction center, accessory and photoprotective pigments in photosynthesis. Their unique individual photochemical properties are a consequence of the tetrapyrrole macrocycle, the structural chemistry and coordination behavior of the phytochlorin system, and specific substituent pattern. They achieve their full potential in solar energy conversion by working in concert in highly complex, supramolecular structures such as the reaction centers and light-harvesting complexes of photobiology. The biochemical function of these structures depends on the controlled interplay of structural and functional principles of the apoprotein and pigment cofactors. Chlorophylls and bacteriochlorophylls are optically active molecules with several chiral centers, which are necessary for their natural biological function and the assembly of their supramolecular complexes. However, in many cases the exact role of chromophore stereochemistry in the biological context is unknown. This review gives an overview of chlorophyll research in terms of basic function, biosynthesis and their functional and structural role in photosynthesis. It highlights aspects of chirality and symmetry of chlorophylls to elicit further interest in their role in nature.

  11. 1Application of Fluorescence Resonance Energy Transfer and Magnetic Twisting Cytometry to Quantitate Mechano-Chemical Signaling Activities in a Living Cell

    Science.gov (United States)

    Na, Sungsoo; Wang, Ning

    2009-01-01

    Mechanotransduction is the process by which living cells sense mechanical forces and then convert them into biochemical signaling. Recently we showed that mechanical stress is transduced from the cell surface to remote cytoplasmic sites within 0.3 s, which is at least 40 to 50 times faster than soluble factor-induced signal transduction, and the sites of mechanotransduction colocalize with sites where mechanical stress causes microtubule displacement. These results suggest that mechanotransduction employs mechanisms different from those of soluble factor-induced signal transduction. Here we describe a protocol that utilizes fluorescence resonance energy transfer (FRET) and a magnetic twisting cytometry (MTC) device to capture rapid mechano-chemical signaling activities in living cells. PMID:18728305

  12. Chlorophyll modulation of mixed layer thermodynamics in a mixed-layer isopycnal General Circulation Model - An example from Arabian Sea and equatorial Pacific

    Indian Academy of Sciences (India)

    S Nakamoto; S Prasanna Kumar; J M Oberhuber; H Saito; K Muneyama; R Frouin

    2002-09-01

    Western tropical Indian Ocean, Arabian Sea, and the equatorial Pacific are known as regions of intense bio-chemical-physical interactions: the Arabian Sea has the largest phytoplankton bloom with seasonal signal, while the equatorial Pacific bloom is perennial with quasi-permanent upwelling. Here, we studied three dimensional ocean thermodynamics comparing recent ocean observation with ocean general circulation model (OPYC) experiment combined with remotely sensed chlorophyll pigment concentrations from the Coastal Zone Color Scanner (CZCS). Using solar radiation parameterization representing observations that a higher abundance of chlorophyll increases absorption of solar irradiance and heating rate in the upper ocean, we showed that the mixed layer thickness decreases more than they would be under clear water conditions. These changes in the model mixed layer were consistent with Joint Global Ocean Flux Study (JGOFS) observations during the 1994-1995 Arabian Sea experiment and epi-fluorescence microscopy (EFM) on samples collected during Equatorial Pacific Ocean Climate Study (EPOCS) in November, 1988. In the Arabian Sea, as the chlorophyll concentrations peak in October (3mg/m3) after the summer plankton bloom induced by coastal upwelling, the chlorophyll induced biological heating enhanced the sea surface temperature (SST) by as much as 0.6°C and sub-layer temperature decreases and sub-layer thickness increases. In the equatorial Pacific, modest concentrations of chlorophyll less than 0.3mg/m3 is enough to introduce a meridional differential heating, which results in reducing the equatorial mixed layer thickness to more than 20 m. The anomalous meridional tilting of the mixed layer bottom enhances off equatorial westward geostrophic currents. Consequently, the equatorial undercurrent transports more water from west to east. We proposed that these numerical model experiments with use of satellite and in situ ocean observations are consistent under three

  13. Spinach seed quality - potential for combining seed size grading and chlorophyll flourescence sorting

    DEFF Research Database (Denmark)

    Deleuran, Lise Christina; Olesen, Merete Halkjær; Boelt, Birte

    2013-01-01

    might therefore improve the establishment of spinach for producers. Spinach seeds were harvested at five different times (H1, H2, H3, H4 and H5) starting 3 weeks before estimated optimum harvest time. The harvested seeds were sorted according to chlorophyll fluorescence (CF) and seed size. Two harvest.......5–3.25 mm size seeds had germinated on day 3 than both their larger and smaller counterparts at the later time of harvest (H4). Seeds with a diameter below 2.5 mm displayed the lowest MGT. Commercially, the use of chlorophyll fluorescence (CF)-sorted seeds, in combination with seed size sorting, may provide...

  14. Spectral luminescence and photochemical properties of chlorophyll a in solution containing carbon tetrachloride

    International Nuclear Information System (INIS)

    Studies were conducted on photophysical and photochemical processes in chlorophyll a in carbon tetrachloride and ether by means of flash photolysis, electron spin resonance, and fluorescence spectroscopy. Lifetimes and quenching of triplet states were analyzed and absorption spectra and fluorescence decay times are given. The kinetics of triplet-triplet absorption and hyperfine structure were determined. An absolute quantum yield of the photochemical reaction was measured within the range of linear dependence of the optical density on the time of chlorophyll a irradiation by a krypton laser and the excitation wavelength of 647.1 nm

  15. 铜胁迫对苋菜叶片叶绿素a荧光诱导动力学的影响%Effects of Copper Stress on the Chlorophyll a Fluorescence Induction Kinetics of Amaranthus mangostanus L.

    Institute of Scientific and Technical Information of China (English)

    林碧英; 谢秋梅; 林义章; 朱海生; 李永裕

    2011-01-01

    The effect of Cu-added nutrient fluid on the root of A rnaranthus mangostanus L. was investigated in this experiment. Also, the function changes of the photosystem Ⅱ (PS Ⅱ ) reaction center in A maranthus mangostanus L.,and the influences of copper in donor and acceptor sides of this system were investigated by the method of fluorescence induction kinetics. The results showed that copper stress inactivated the PS Ⅱ reaction center in the leaves of Amaranthus mangostanus L., decreased the maximal photochemical efficiency of PSⅡ (FV/FM), and damaged the acceptor side of PS Ⅱ seriously and inhibited the transfer of linear electrons, and also did harm to the oxygen evolving complexes (OEC) of the donor side of PS Ⅱ. It could be concluded that the damage of copper stress in Amaranthus mangostanus L. was begun from the donor and acceptor sides of PsⅡin leaves.%以苋菜(Amaranthus mangostanus L.)为材料,采用营养液中添加铜的培养方法,观测了根部生长变化:运用叶绿素荧光分析技术研究了铜胁迫下苋菜光系统Ⅱ(PSⅡ)反应中心结构和功能的变化以及PSⅡ反应中心供体侧和受体侧氧化还原状态的影响.结果表明:铜胁迫使苋菜根部生长受到抑制,叶片PSⅡ反应中心失活:最大光化学效率(FV/FM)下降;叶片PSⅡ受体侧产生严重的伤害,线性电子传递受阻;PSⅡ供体侧的放氧复合体(0EC)受损;铜胁迫对苋菜叶片PSⅡ的伤害从PSⅡ供体侧和受体侧开始.

  16. MATtrack: A MATLAB-Based Quantitative Image Analysis Platform for Investigating Real-Time Photo-Converted Fluorescent Signals in Live Cells.

    Science.gov (United States)

    Courtney, Jane; Woods, Elena; Scholz, Dimitri; Hall, William W; Gautier, Virginie W

    2015-01-01

    We introduce here MATtrack, an open source MATLAB-based computational platform developed to process multi-Tiff files produced by a photo-conversion time lapse protocol for live cell fluorescent microscopy. MATtrack automatically performs a series of steps required for image processing, including extraction and import of numerical values from Multi-Tiff files, red/green image classification using gating parameters, noise filtering, background extraction, contrast stretching and temporal smoothing. MATtrack also integrates a series of algorithms for quantitative image analysis enabling the construction of mean and standard deviation images, clustering and classification of subcellular regions and injection point approximation. In addition, MATtrack features a simple user interface, which enables monitoring of Fluorescent Signal Intensity in multiple Regions of Interest, over time. The latter encapsulates a region growing method to automatically delineate the contours of Regions of Interest selected by the user, and performs background and regional Average Fluorescence Tracking, and automatic plotting. Finally, MATtrack computes convenient visualization and exploration tools including a migration map, which provides an overview of the protein intracellular trajectories and accumulation areas. In conclusion, MATtrack is an open source MATLAB-based software package tailored to facilitate the analysis and visualization of large data files derived from real-time live cell fluorescent microscopy using photoconvertible proteins. It is flexible, user friendly, compatible with Windows, Mac, and Linux, and a wide range of data acquisition software. MATtrack is freely available for download at eleceng.dit.ie/courtney/MATtrack.zip.

  17. A new colorimetric and fluorescent bis(coumarin)methylene probe for fluoride ion detection based on the proton transfer signaling mode

    Energy Technology Data Exchange (ETDEWEB)

    Mahapatra, Ajit Kumar, E-mail: akmahapatra@rediffmail.com; Maiti, Kalipada; Sahoo, Prithidipa; Nandi, Prasanta Kumar

    2013-11-15

    A new turn-on fluorescent and colorimetric sensor, oxidized bis(coumarin)methane (1) for fluoride in acetonitrile was designed and synthesized. The binding ability evaluated by UV–vis and fluorescence titration experiments reveals that 1 can selectively interact with fluoride. Upon addition of fluoride to receptor 1 in acetonitrile solution, the appearance of a new absorption band around 349 nm showed a color change from colorless to yellow, which can provide a way of ‘naked eye’ detection of fluorides. The spectral change of 1 is due to the anion induced deprotonation and hence an increase in charge density and rigidity of the receptor molecule. Furthermore, the binding mode with fluoride was investigated by {sup 1}H NMR titration experiments. Again, the deprotonation of oxidized bis(coumarin)methane 1 is responsible for the color change. -- Graphical abstract: A new colorimetric and fluorescent bis(coumarin)methylene probe for fluoride ion detection based on the proton transfer signaling mode. Highlights: • The first report of conjugated biscoumarin-based colorimetric chemosensor. • Oxidized bis(coumarin)methane acts as colorimetric reporter. • The oxidized coumarin moiety might modulate the internal charge transfer (ICT). • Fluorescence turn-on sensing of fluoride.

  18. A robust and versatile signal-on fluorescence sensing strategy based on SYBR Green I dye and graphene oxide

    Directory of Open Access Journals (Sweden)

    Qiu HZ

    2014-12-01

    Full Text Available Huazhang Qiu,1,* Namei Wu,1,* Yanjie Zheng,1 Min Chen,2 Shaohuang Weng,1 Yuanzhong Chen,3 Xinhua Lin1 1Department of Pharmaceutical Analysis, Faculty of Pharmacy, Fujian Medical University, Fuzhou, People’s Republic of China; 2Department of Orthopedic Surgery, Affiliated Union Hospital of Fujian Medical University, Fuzhou, People’s Republic of China; 3Fujian Institute of Hematology, The Affiliated Union Hospital of Fujian Medical University, Fuzhou, People’s Republic of China *These authors contributed equally to this work Abstract: A robust and versatile signal-on fluorescence sensing strategy was developed to provide label-free detection of various target analytes. The strategy used SYBR Green I dye and graphene oxide as signal reporter and signal-to-background ratio enhancer, respectively. Multidrug resistance protein 1 (MDR1 gene and mercury ion (Hg2+ were selected as target analytes to investigate the generality of the method. The linear relationship and specificity of the detections showed that the sensitive and selective analyses of target analytes could be achieved by the proposed strategy with low detection limits of 0.5 and 2.2 nM for MDR1 gene and Hg2+, respectively. Moreover, the strategy was used to detect real samples. Analytical results of MDR1 gene in the serum indicated that the developed method is a promising alternative approach for real applications in complex systems. Furthermore, the recovery of the proposed method for Hg2+ detection was acceptable. Thus, the developed label-free signal-on fluorescence sensing strategy exhibited excellent universality, sensitivity, and handling convenience. Keywords: fluorescence, turn-on, SYBR Green I, graphene oxide, multidrug resistance protein 1 gene, Hg2+

  19. Effects of five kinds of antibiotics stressed on chlorophyll fluorescence parameters of Isochrysis sp.CCMMS001%五种抗生素对等鞭金藻(Isochrysis sp. CCMMS001)叶绿素荧光特性的影响

    Institute of Scientific and Technical Information of China (English)

    郑明刚; 郑立; 王玲; 韩笑天; 李海东; 崔志松

    2011-01-01

    利用PHYTO-PAM测定了抗生素胁迫下等鞭金藻(Isochrysis sp.CMMS001)叶绿素荧光参数Fv/ Fm(PSⅡ的最大光能转化效率)的变化规律.结果表明:不同抗生素对等鞭金藻Fv/ Fm的影响存在很大差异,氯霉素、G-418能显著抑制其最大光能转化效率;潮霉素抑制作用次之;卡那霉素、氨苄青霉素没有抑制作用.在f/2培养基中,浓度为600 mg/L氯霉素胁迫下,第3d测得Fv/ Fm值下降97%.在f/2培养基中,浓度为1 200 mg/L潮霉素和500 mg/L G-418胁迫下,第6d测得Fv/Fm值分别下降52%、98%.在淡化5倍f/2培养基中,浓度为1200 mg/L潮霉素和500 mg/L G-418胁迫下,第6d测得的Fv Fm值分别下降77%、100%.卡那霉素、氨苄青霉素胁迫下,Fv/ Fm随着两种抗生素浓度的增加没有降低,反而上升.%The different concentrations of antibiotics stressing on chlorophyll fluorescence parameters Fv/Fm ( PS II maximum solar energy conversion efficiency) of Isochrysis sp. Were determined by Phyto-PAM. The results showed that there was large difference in the impact of different antibiotics on chlorophyll fluorescence parameters Fv/Fm of Isochrysis sp.. Chloramphenicol,C-418 could significantly inhibit the maximum solar energy conversion efficiency of Isochrysis sp. The effect followed by the hygromycin. The effect was not observed by kanamycin and ampicilin for the maximum solar energy conversion efficency of Isochrysis sp. In the f/2 medium, stressed by chloramphenicol with concentration of 600 mg/L,Fv/Fm of Isochrysis sp. Decreased by 97% on the third day. In f/2 medium,stressed by hygromycin with the concentrations of 1 200 mg/L and 500 mg/L G-418 ,Fv/Fm of Isochrysis sp. Decreased by 52% and 98% on the 6th day. In f/2 medium diluted S times,stressed by hygromycin with the concentration of 1 200 mg/L and G-418 with the concentration of 500 mg/L,Fv/Fm of Isochrysis sp. Decreased by 77% and 100% on 6th day. With increasing concentrations of Kanamycin and ampicillin

  20. Reconstitution of Photosystem Ⅱ Reaction Center with Cu-Chlorophyll a

    Institute of Scientific and Technical Information of China (English)

    Shuang Liu; Feng-Qin Dong; Chun-Hong Yang; Chong-Qin Tang; Ting-Yun Kuang

    2006-01-01

    An isolated photosystem (PS) Ⅱ reaction center (RC) with altered pigment content was obtained by chemical exchange of native chlorophyll a (Chl) with externally added Cu-Chl a (Cu-Chl). Pigment composition and spectroscopic properties of the RC exchanged with Cu-Chl were compared with native RC and RC treated with Chl in the same way. High-performance liquid chromatography analysis showed approximately 0.5 Cu-Chl per two pheophytin in the Cu-Chl-reconstituted RC preparation. Insertion of Cu-Chl resulted in a decrease in absorption at 670 nm and an increase at 660 nm, suggesting that the peripheral Chl may have been displaced. Fluorescence emission spectra of the Cu-Chl-reconstituted RC displayed a marked decrease in fluorescence yield and a blue shift of the band maximum, accompanied by the appearance of a broad peak at a shorter wavelength, indicating that energy transfer in the modified RC was disturbed by Cu-Chl, a quencher of the excited state. However, there were few differences in the circular dichroism (CD) spectra,suggesting that the arrangement of pigments and proteins responsible for the CD signal was not significantly affected. In addition, no obvious change in peptide components was found after the exchange procedure.

  1. Extraction and Analysis of Solar-Induced Chlorophyll Fluorescence of Wheat with Ground-Based Hyperspectral Imaging System%基于近地面高光谱影像的冬小麦日光诱导叶绿素荧光提取与分析

    Institute of Scientific and Technical Information of China (English)

    王冉; 刘志刚; 冯海宽; 杨沛琦; 王庆山; 倪卓娅

    2013-01-01

    结合FluorMOD模型模拟数据与利用光谱分辨率3.3nm、光谱采样间隔为0.71~0.74 nm近地面成像高光谱系统获取的抽穗期小麦高光谱影像比较3种基于夫琅和费线暗线的提取方法(FLD,3FLD和iFLD)的精确性和稳定性.结果表明当光谱分辨率为3.3nm时,在760 m附近的O2-A波段可以有效提取日光诱导叶绿素荧光,而在687 nm附近的O2-B波段不适合.当存在噪声时,FLD和3FLD的稳定性高于iFLD,FLD倾向于高估荧光值.%Dataset simulated with FluorMOD and images of wheat in heading stage taken by a ground-based hyperspectral imaging system with 3.3 nm spectral resolution and 0.71~0.74 nm spectral sampling interval were used test the feasibility and accuracy of three FLD methods (named FLD,3FLD and iFLD).The results show that when spectral resolution is 3.3 nm,solarinduced chlorophyll fluorescence could be extracted effectively in O2-A band (around 760 nm) instead of O2-B band (around 687nm).As to the extraction results of data with noises,both FLD and 3FLD are stabler than iFLD method.The results of FLD tend to be higher than true value.

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

    Science.gov (United States)

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

    2016-06-01

    We used a willow species (Salix miyabeana cultivar SX64) to examine the differential secondary-effects of glyphosate and aminomethylphosphonic acid (AMPA), the principal glyphosate by-product, on chlorophyll metabolism and photosynthesis. Willow plants were treated with different concentrations of glyphosate (equivalent to 0, 1.4, 2.1 and 2.8kgha(-1)) and AMPA (equivalent to 0, 0.28, 1.4 and 2.8kgha(-1)) and evaluations of pigment contents, chlorophyll fluorescence, and oxidative stress markers (hydrogen peroxide content and antioxidant enzyme activities) in leaves were performed after 12h of exposure. We observed that AMPA and glyphosate trigger different mechanisms leading to decreases in chlorophyll content and photosynthesis rates in willow plants. Both chemicals induced ROS accumulation in willow leaves although only glyphosate-induced oxidative damage through lipid peroxidation. By disturbing chlorophyll biosynthesis, AMPA induced decreases in chlorophyll contents, with consequent effects on photosynthesis. With glyphosate, ROS increases were higher than the ROS-sensitive threshold, provoking chlorophyll degradation (as seen by pheophytin accumulation) and invariable decreases in photosynthesis. Peroxide accumulation in both AMPA and glyphosate-treated plants was due to the inhibition of antioxidant enzyme activities. The different effects of glyphosate on chlorophyll contents and photosynthesis as described in the literature may be due to various glyphosate:AMPA ratios in those plants. PMID:27155486

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

    Science.gov (United States)

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

    2016-06-01

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

  4. 铝胁迫下外源有机酸对油菜根系形态及叶绿素荧光特性的影响%Effects of exogenous organic acids on root morphology and chlorophyll fluorescence characteristics of oilseed rape under aluminum stress

    Institute of Scientific and Technical Information of China (English)

    王志颖; 刘鹏; 李锦山; 吴惠芳; 刘莹; 芦伯鑫

    2011-01-01

    Aluminum toxicity in acidic soil has become a major limiting factor in China' s rapeseed oil production. To investigate the effects of exogenous organic acids (citric acid or malic acid) on root morphology and chlorophyll fluorescence characteristics of different Al-tolerant varieties of oilseed rape (Huayou 2790 and Zhongshuang No. 7) , relative root length and total root length as well as chlorophyll fluorescence parameters [ the chlorophyll content, Fm(maximal fluorescence) , Fv/Fo(PS II potential activity) ,φPS II (photochemical quantum yield) ] of oilseed rape with interactive treatments of aluminum (0μmol/L, 50μmol/L,100μmol/L,200μmol/L) and two organic acids (citric acid or malic acid, 20μmol/L) were determined under hydroponics condition. Results showed that, in single aluminum treatment, ail the parameters mentioned above reduced as the Al concentration increased, the sensitive cultivar Huayou 2790 dropping morethan tolerant cultivar Zhongshuang No. 7. After adding exogenous organic acids, the above parameters were unproved. In 200μmol/L Al and organic acid interactive treatment, the relative root length was increased by 14. 9% for Al-tolerant cultivar compared with the same concentration of single Al. The increment of chlorophyllfluorescence parameters in Al-tolerant cultivar were larger than those in Al-sensitive one, and the alleviating effects of citric acid was slightly better than malic acid. It indicated that aluminum stress could inhibit the root growth and photosynthesis of oilseed rape, and adding exogenous organic acids could alleviate the toxicity of aluminum to a certain extent.%为探明铝胁迫下外源有机酸(柠檬酸和苹果酸)对不同耐性油菜品种(华油2790和中双7号)根系形态和叶绿素荧光特性的影响,该研究采用水培法,用分光光度计、根系扫描仪等测定0 μmol/L、50 μmol/L、100μmol/L、200 μmol/L铝和20 μmol/L柠檬酸或苹果酸瓦作处理下油菜根系的形态指标及叶

  5. Field Detection of Chlorophyll-a Concentration in the Sea Surface Layer by an Airborne Oceanographic Lidar

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An airborne oceanographic lidar, with a frequency-tripled Q-switched Nd: YAG laser of 355 nm, has been designed to measure chlorophyll-a (Chl-a) concentration in the sea surface layer by the Ocean Remote Sensing Institute, OUC. The field experiment was carried out in the bay which is located south of the Liaodong Peninsula on the 10th of September 2005. After the flight, the raw data were processed and analyzed by the fluorescence-to-Raman ratio method with seawater attenuation coefficients calculated from signal profiles. The results of Chl-a concentration measurements by lidar are shown. The measurements in clear sea water were also compared with those of Chl-a concentration by a Moderate Resolution Imaging Spectroradiometer (MODIS).

  6. Green Fluorescent Protein (GFP)-tagged Cysteine-rich Domains from Protein Kinase C as Fluorescent Indicators for Diacylglycerol Signaling in Living Cells

    OpenAIRE

    Oancea, Elena; Teruel, Mary N.; Quest, Andrew F.G.; Meyer, Tobias

    1998-01-01

    Cysteine-rich domains (Cys-domains) are ∼50–amino acid–long protein domains that complex two zinc ions and include a consensus sequence with six cysteine and two histidine residues. In vitro studies have shown that Cys-domains from several protein kinase C (PKC) isoforms and a number of other signaling proteins bind lipid membranes in the presence of diacylglycerol or phorbol ester. Here we examine the second messenger functions of diacylglycerol in living cells by monitoring the membrane tra...

  7. Studying Photosynthesis by Measuring Fluorescence

    Science.gov (United States)

    Sanchez, Jose Francisco; Quiles, Maria Jose

    2006-01-01

    This paper describes an easy experiment to study the absorption and action spectrum of photosynthesis, as well as the inhibition by heat, high light intensity and the presence of the herbicide 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) on the photosynthetic process. The method involves measuring the chlorophyll fluorescence emitted by intact…

  8. High-resolution imaging of redox signaling in live cells through an oxidation-sensitive yellow fluorescent protein

    DEFF Research Database (Denmark)

    Maulucci, Giuseppe; Labate, Valentina; Mele, Marina;

    2008-01-01

    quantitation of the distribution of fluorescence by confocal microscopy, allows us to draw real-time "redox maps" of adherent cells and to score subtle changes in the intracellular redox state, such as those induced by overexpression of redox-active proteins. This strategy for in vivo imaging of redox...

  9. Obsolete - AFSC/RACE/Eco-FOCI: Chlorophyll: groundtruth data for chlorophyll fluorescence sensors on the moorings.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are part of a ocean observation study by Stabeno, Napp, and Whitledge sponsored, in part, but the North Pacific Research Board (Project 410;...

  10. Plankton studies in San Francisco Bay; I, Chlorophyll distributions and hydrographic properties, July 1977-December 1979

    Science.gov (United States)

    Alpine, Andrea E.; Cloern, James E.; Cole, Brian E.

    1981-01-01

    This report summarizes the distribution of phytoplankton biomass and selected hydrographic properties measured in the San Francisco Bay Estuary, on a near-monthly basis, from July 1977 through December 1979. Parameters measured were: chlorophyll a, phaeopigments, in-vivo fluorescence, turbidity, size distribution of phytoplankton, salinity and temperature. (USGS)

  11. Effects of the Dithiothretiol on Activate Oxygen Metabolism and Chlorophyll Fluorescences in Spinach Leaves Under Seawater Stress%二硫苏糖醇对海水胁迫下菠菜活性氧代谢及叶绿素荧光特性的影响

    Institute of Scientific and Technical Information of China (English)

    陈新斌; 孙锦; 郭世荣; 陆晓民; 何立中; 严蓓

    2012-01-01

    以耐海水菠菜品种‘荷兰3号’为材料,采用水培方法,研究了二硫苏糖醇(DTT)对海水胁迫及甲基紫精(MV)诱导下菠菜活性氧代谢及叶绿素荧光特性的影响。结果表明,海水胁迫与MV处理一样,诱导菠菜叶片产生氧化胁迫,使超氧阴离子(噶)产生速率、过氧化氢(H202)含量和丙二醛(MDA)含量显著上升,叶绿素a(Chl.a)、叶绿素b(Chl-b)、总叶绿素[Chl.(a+b)]和类胡萝卜素(Car.)含量显著下降,最大光量子产量(砜)、实际光量子产量(yiP膨)、电子传递速率(ETR)和光化学猝灭系数(卯)显著降低,而非光化学猝灭系数(NPQ/4)显著上升;海水胁迫与MV处理下,由叶柄导入叶黄素循环活性抑制剂DTT,菠菜叶片活性氧(ROS)大量积累,导致光合色素降解加剧,砜、m埘、ETR、NPQ、qP进一步下降。上述结果表明,海水胁迫抑制了菠菜叶片叶黄素循环活性,降低了叶片非辐射能量耗散能力,加重了叶片ROS积累,从而导致光合色素含量降低,PsII活性下降,电子传递速率降低,用于光化学反应的能量部分减少,光合作用受到严重影响,说明海水胁迫下叶黄素循环在保持菠菜叶片光合色素稳定和光合作用正常运转中发挥重要作用。%The effects of the dithiothretiol (DTT) on activate oxygen metabolism and chlorophyll fluorescences under seawater stress and methyl viologen (MV)induced oxidative stress in leaves of'Helan 3' (seawater tolerant cultivar) were investigated by hydroponics. The results shown that production rate of superoxide radical (O2), content of hydrogen peroxide (H202) and malonaldehyde (MDA) were remarkably increased by seawater and MV which could induce oxidative stress on spinach leaves, whereas contents of chlorophyll a (Chl.a), chlorophyll b (Chl.b), total chlorophyll and carotenoid (Car.) remarkably decreased. Under

  12. Novel fluorescent ELISA for the sensitive detection of zearalenone based on H2O2-sensitive quantum dots for signal transduction.

    Science.gov (United States)

    Zhan, Shengnan; Huang, Xiaolin; Chen, Rui; Li, Juan; Xiong, Yonghua

    2016-09-01

    A direct competitive fluorescent enzyme-linked immunosorbent assay (ELISA) was developed for the detection of zearalenone (ZEN) using ZEN labeled catalase (CAT) as a competing antigen with H2O2-sensitive CdTe quantum dots (QDs) for signal transduction. The novel fluorescent ELISA showed very high sensitivity for ZEN detection because it combined the high catalytic activity of CAT to H2O2 and H2O2-sensitive property of QDs. Under optimal conditions, the developed method showed a good dynamic linear detection for ZEN in the range of 2.4pg/mL to 1.25ng/mL with a detection limit of 4.1pg/mL. The median inhibition concentration (IC50) of ZEN was 75pg/mL, which was approximately 17-fold lower than that of horseradish peroxidase-based conventional ELISA. Moreover, our developed method also showed a high reproducibility and an excellent selectivity. In brief, the novel fluorescent ELISA shows great potential for the sensitive and economic detection of mycotoxins and other analytes in food analysis, clinical diagnosis and environmental monitoring.

  13. Novel fluorescent ELISA for the sensitive detection of zearalenone based on H2O2-sensitive quantum dots for signal transduction.

    Science.gov (United States)

    Zhan, Shengnan; Huang, Xiaolin; Chen, Rui; Li, Juan; Xiong, Yonghua

    2016-09-01

    A direct competitive fluorescent enzyme-linked immunosorbent assay (ELISA) was developed for the detection of zearalenone (ZEN) using ZEN labeled catalase (CAT) as a competing antigen with H2O2-sensitive CdTe quantum dots (QDs) for signal transduction. The novel fluorescent ELISA showed very high sensitivity for ZEN detection because it combined the high catalytic activity of CAT to H2O2 and H2O2-sensitive property of QDs. Under optimal conditions, the developed method showed a good dynamic linear detection for ZEN in the range of 2.4pg/mL to 1.25ng/mL with a detection limit of 4.1pg/mL. The median inhibition concentration (IC50) of ZEN was 75pg/mL, which was approximately 17-fold lower than that of horseradish peroxidase-based conventional ELISA. Moreover, our developed method also showed a high reproducibility and an excellent selectivity. In brief, the novel fluorescent ELISA shows great potential for the sensitive and economic detection of mycotoxins and other analytes in food analysis, clinical diagnosis and environmental monitoring. PMID:27343577

  14. Novel signal-amplifying fluorescent nanofibers for naked-eye-based ultrasensitive detection of buried explosives and explosive vapors

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ying; La, Anthony; Ding, Yu; Liu, Yixin; Lei, Yu [Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, Storrs, CT (United States)

    2012-09-11

    A novel electrospun fluorescent nanofiberous membrane with a function like ''molecular wires'' was developed via electrospinning for the detection of ultra-trace nitro explosive vapors and buried explosives by naked eye under UV excitation. The high binding affinity between the electron-deficient nitro explosives and the sensing film results in a rapid, dramatic quenching in its fluorescence emission. A wide spectrum of nitro explosives, in particular, TNT, Tetryl, RDX, PETN and HMX could be ''visually'' detected at their sub-equilibrium vapors (less than 10 ppb, 74 ppt, 5 ppt, 7 ppt and 0.1 ppt, respectively) released from 1 ng explosives residues. Such outstanding sensing performance could be attributed to the proposed ''sandwich-like'' conformation between pyrene and phenyl pendants of PS which may allow efficient long-range energy migration similar to ''molecular wire'', thus achieving amplified fluorescence quenching. Its application for the detection of buried explosives in soil by naked eye was also demonstrated, indicating its potential application for landmine mapping. To the best of our knowledge, this is the first report about the detection of buried explosives without the use of any advanced analytical instrumentation. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Does Litter Impart A Detectable Chemical Signal on Soil DOC? DOC Fluorescence Signatures in Soils Undergoing Long-Term Litter Manipulations

    Science.gov (United States)

    Lajtha, K.; Strid, A.; Lee, B. S.

    2015-12-01

    Soil dissolved organic carbon (DOC) is a small but crucial part of the forest carbon cycle. Characterizing the relationship between organic matter inputs to soil and DOC chemistry is crucial to understanding the ultimate fate of root carbon, fallen wood and needles. Chemical differences in the DOC pool may help to explain whether fractions are sorbed to mineral surfaces and contribute to accumulation of soil organic carbon, respired as CO2, or exported. Soil solution DOC was sampled from the detrital input and removal treatment (DIRT) plots located in the H.J. Andrews Experimental Forest, OR to determine whether detrital inputs impart a detectable signal on DOC in mineral soil. Multiple types of fresh litter extracts, along with lysimeter and soil extracts from DIRT treatment plots were characterized using UV-Vis and fluorescence spectroscopy coupled with the Cory and McKnight (2005) parallel factor analysis (PARAFAC) model. Principal component analysis of 13 unique fluorophores distinguished using PARAFAC show that litter and soil extracts (needles, wood of decomposition Class 1, Class 3 and Class 5, O-horizon, and A-horizon) each have distinct fluorescence signatures. However, while litter-leached DOC chemistry varies by litter type, neither lysimeter-collected DOC or soil extracts show statistically significant differences in fluorescence signatures among treatments, even after 17 years of litter manipulations. The lack of observed differences among DIRT treatments suggests a "Soil Blender" hypothesis whereby both abiotic and biotic mechanisms effectively homogenize organic carbon constituents within the dissolved pool. The results of this work emphasize the ability of sorption and biodegradation to homogenize soil DOC and demonstrate that fluorescence can be an effective fingerprinting technique for soil DOC composition.

  16. 丛枝菌根真菌(AMF)对低温胁迫下黄瓜幼苗生长及叶绿素荧光参数的影响%Effects of Arbuscular Mycorrhiza Fungi on Seedlings Growth and Chlorophyll Fluorescence Parameters in Cucumber under Low Temperature Stress

    Institute of Scientific and Technical Information of China (English)

    曹岩坡; 戴鹏; 戴素英

    2016-01-01

    以黄瓜品种津优303为试验材料,设低温+灭菌接种物、常温+菌剂、低温+菌剂3个处理,以常温+灭菌接种物处理为对照,研究了接种丛枝菌根真菌(AMF)对低温胁迫下黄瓜幼苗生长及叶绿素荧光参数的影响。结果表明:低温胁迫下黄瓜幼苗生长量(株高,地上部和地下部的鲜重与干重)、黄瓜幼苗叶片光合参数(净光合速率、气孔导度、蒸腾速率和叶绿素含量)以及叶绿素荧光参数[最大荧光(Fm)、初光能转换效率(Fv/Fm)、PSII的潜在光化学活性(Fv/F0)]均显著约CK,严重抑制了黄瓜幼苗的生长;初始荧光(F0)显著>CK,PSII反应中心遭受损害。低温胁迫下接种AMF处理的黄瓜幼苗生长量以及叶片幼苗光合参数和叶绿素荧光参数指标值均显著>未接种AMF处理,F0显著约未接种AMF处理,其中,叶绿素含量提高10.24%,Fm、Fv/Fm和Fv/F0分别提高14.2%、5.9%和31.4%,F0降低8%,明显缓解低温胁迫对幼苗的伤害。%The effects of inoculation of arbuscular mycorrhiza fungi on seedlings growth and chlorophyll fluorescent characteristics of seedlings of cucumber (Jinyou 303) under low temperature stress were inves-tigated in the growth chamber. The results showed that AMF inoculation treatment could significantly pro-mote the seedlings height,fresh weight,dry weigh under low temperature stress. Compared with the con-trol treatment,AMF inoculation treatment could significantly promote the chlorophyll contents by 10.24%, and increment Fm,Fv/Fm,Fv/F0 by 14.2%,5.9% and 31.4%,while reduced F0 by 8%.

  17. Fluorescence, Aqua MODIS, NPP, 0.125 degrees, West US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures chlorophyll fluorescence, which gives insight into the physiology of phytoplankton in the ocean. When phytoplankton are under stress, the rate at...

  18. Fluorescence, Aqua MODIS, NPP, 0.125 degrees, East US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures chlorophyll fluorescence, which gives insight into the physiology of phytoplankton in the ocean. When phytoplankton are under stress, the rate at...

  19. Is It Possible to Distinguish Between Dust and Salt Aerosol Over Waters with Unknown Chlorophyll Concentrations Using Spectral Remote Sensing?

    Science.gov (United States)

    Levy, R. C.; Kaufman, Y. J.

    1999-01-01

    Atmospheric aerosol has uncertain impacts on the global climate system, as well as on atmospheric and bio-geo-chemical processes of regional and local scales. EOS-MODIS is one example of a satellite sensor designed to improve understanding of the aerosols' type, size and distribution at all temporal and spatial scales. Ocean scientists also plan to use data from EOS-MODIS to assess the temporal and spatial coverage of in-water chlorophyll. MODIS is the first sensor planned to observe the combined ocean-atmosphere system with a wide spectral range (from 410 to 2200 nm). Dust aerosol and salt aerosol have similar spectral signals for wavelengths longer than 550 nm, but because dust selectively absorbs blue light, they have divergent signals in the blue wavelength regions (412 to 490 nm). Chlorophyll also selectively absorbs blue radiation, so that varying chlorophyll concentrations produces a highly varying signal in the blue regions, but less variability in the green, and almost no signal in the red to mid-infrared regions. Thus, theoretically, it may be difficult to differentiate dust and salt in the presence of unknown chlorophyll in the ocean. This study attempts to address the cases in which aerosol and chlorophyll signals can and cannot be separated. For the aerosol spectra, we use the aerosol lookup table from the operational MODIS aerosol-over-ocean algorithm, and for chlorophyll spectra, we use the SeaBAM data set (created for SeaWiFS). We compare the signals using Principal Component Analysis and attempt to retrieve both chlorophyll and aerosol properties using a variant of the operational MODIS aerosol-over-ocean algorithm. Results show that for small optical depths, less than 0.5, it is not possible to differentiate between dust and salt and to determine the chlorophyll concentration at the same time. For larger aerosol optical depths, the chlorophyll signals are comparatively insignificant, and we can hope to distinguish between dust and salt.

  20. A Method to Reconstruct the Solar-Induced Canopy Fluorescence Spectrum from Hyperspectral Measurements

    Directory of Open Access Journals (Sweden)

    Feng Zhao

    2014-10-01

    Full Text Available A method for canopy Fluorescence Spectrum Reconstruction (FSR is proposed in this study, which can be used to retrieve the solar-induced canopy fluorescence spectrum over the whole chlorophyll fluorescence emission region from 640–850 nm. Firstly, the radiance of the solar-induced chlorophyll fluorescence (Fs at five absorption lines of the solar spectrum was retrieved by a Spectral Fitting Method (SFM. The Singular Vector Decomposition (SVD technique was then used to extract three basis spectra from a training dataset simulated by the model SCOPE (Soil Canopy Observation, Photochemistry and Energy fluxes. Finally, these basis spectra were linearly combined to reconstruct the Fs spectrum, and the coefficients of them were determined by Weighted Linear Least Squares (WLLS fitting with the five retrieved Fs values. Results for simulated datasets indicate that the FSR method could accurately reconstruct the Fs spectra from hyperspectral measurements acquired by instruments of high Spectral Resolution (SR and Signal to Noise Ratio (SNR. The FSR method was also applied to an experimental dataset acquired in a diurnal experiment. The diurnal change of the reconstructed Fs spectra shows that the Fs radiance around noon was higher than that in the morning and afternoon, which is consistent with former studies. Finally, the potential and limitations of this method are discussed.

  1. 外源NO对增补UV-B辐射下兴安落叶松幼苗叶片光合色素和叶绿素荧光特性的影响%Effect of Exogenous Nitric Oxide on Photosynthetic Pigments and Chlorophyll Fluorescence under Enhanced UV-B Radiation in Larix gmelinii

    Institute of Scientific and Technical Information of China (English)

    孟庆焕; 祖元刚; 郭晓瑞; 段喜华

    2013-01-01

    在增强UV-B辐射下,以3年生兴安落叶松幼苗为实验材料,研究了外源NO供体硝普钠(Sodium nitroprusside,SNP)对幼苗的光合色素(Chla、Chlb和Car)和叶绿素荧光参数的影响.方差分析结果表明0.5 mmol·L-1的SNP对增补UV-B胁迫下的兴安落叶松幼苗产生显著影响.0.5 mmol·L-1的SNP能够显著抑制增补UV-B辐射后光合色素、Fv/Fm、φPSⅡ、Fv’/Fm’和qP的明显下降以及Chla/Chlb、Fo和NPQ的升高.表明了外源NO能够减轻UV-B辐射胁迫下兴安落叶松幼苗光合反应中心的生理损伤,从而增强兴安落叶松幼苗对增补UV-B辐射胁迫环境的适应能力.%Under enhanced UV-B radiation,3-year-old seedlings of Larix gmelinii were chose as target to study the impact of exogenous nitric oxide on photosynthetic pigments (Chl a,Chl b and Car) and chlorophyll fluorescence.The results of variance analysis showed 0.5 mmol · L-1 sodium nitroprusside (SNP) ,a NO donor,have significant impact on nursery stocks of L.gmelinii under enhanced UV-B radiation stress.0.5 mmol · L-1 SNP can significantly inhibited the apparent decline in photosynthetic pigments,Fy/Fm,ΦPSⅡ ,Fv'/Fm' and qP,and the obvious increase in chl a/chl b,F0 and NPQ after supplement UV-B radiation.All these results indicated that exogenous nitric oxide could reduce the physical damage of photosynthetic reaction centers in seedlings of L.gmelinii under UV-B radiation stress,and enhancement of environmental adaptability of the seedling to supplementary UV-B radiation stress.

  2. Improving x-ray fluorescence signal for benchtop polychromatic cone-beam x-ray fluorescence computed tomography by incident x-ray spectrum optimization: A Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Manohar, Nivedh [Nuclear/Radiological Engineering and Medical Physics Programs, Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Jones, Bernard L. [Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado 80045 (United States); Cho, Sang Hyun, E-mail: scho@mdanderson.org [Department of Radiation Physics and Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)

    2014-10-15

    Purpose: To develop an accurate and comprehensive Monte Carlo (MC) model of an experimental benchtop polychromatic cone-beam x-ray fluorescence computed tomography (XFCT) setup and apply this MC model to optimize incident x-ray spectrum for improving production/detection of x-ray fluorescence photons from gold nanoparticles (GNPs). Methods: A detailed MC model, based on an experimental XFCT system, was created using the Monte Carlo N-Particle (MCNP) transport code. The model was validated by comparing MC results including x-ray fluorescence (XRF) and scatter photon spectra with measured data obtained under identical conditions using 105 kVp cone-beam x-rays filtered by either 1 mm of lead (Pb) or 0.9 mm of tin (Sn). After validation, the model was used to investigate the effects of additional filtration of the incident beam with Pb and Sn. Supplementary incident x-ray spectra, representing heavier filtration (Pb: 2 and 3 mm; Sn: 1, 2, and 3 mm) were computationally generated and used with the model to obtain XRF/scatter spectra. Quasimonochromatic incident x-ray spectra (81, 85, 90, 95, and 100 keV with 10 keV full width at half maximum) were also investigated to determine the ideal energy for distinguishing gold XRF signal from the scatter background. Fluorescence signal-to-dose ratio (FSDR) and fluorescence-normalized scan time (FNST) were used as metrics to assess results. Results: Calculated XRF/scatter spectra for 1-mm Pb and 0.9-mm Sn filters matched (r ≥ 0.996) experimental measurements. Calculated spectra representing additional filtration for both filter materials showed that the spectral hardening improved the FSDR at the expense of requiring a much longer FNST. In general, using Sn instead of Pb, at a given filter thickness, allowed an increase of up to 20% in FSDR, more prominent gold XRF peaks, and up to an order of magnitude decrease in FNST. Simulations using quasimonochromatic spectra suggested that increasing source x-ray energy, in the

  3. Improving x-ray fluorescence signal for benchtop polychromatic cone-beam x-ray fluorescence computed tomography by incident x-ray spectrum optimization: A Monte Carlo study

    International Nuclear Information System (INIS)

    Purpose: To develop an accurate and comprehensive Monte Carlo (MC) model of an experimental benchtop polychromatic cone-beam x-ray fluorescence computed tomography (XFCT) setup and apply this MC model to optimize incident x-ray spectrum for improving production/detection of x-ray fluorescence photons from gold nanoparticles (GNPs). Methods: A detailed MC model, based on an experimental XFCT system, was created using the Monte Carlo N-Particle (MCNP) transport code. The model was validated by comparing MC results including x-ray fluorescence (XRF) and scatter photon spectra with measured data obtained under identical conditions using 105 kVp cone-beam x-rays filtered by either 1 mm of lead (Pb) or 0.9 mm of tin (Sn). After validation, the model was used to investigate the effects of additional filtration of the incident beam with Pb and Sn. Supplementary incident x-ray spectra, representing heavier filtration (Pb: 2 and 3 mm; Sn: 1, 2, and 3 mm) were computationally generated and used with the model to obtain XRF/scatter spectra. Quasimonochromatic incident x-ray spectra (81, 85, 90, 95, and 100 keV with 10 keV full width at half maximum) were also investigated to determine the ideal energy for distinguishing gold XRF signal from the scatter background. Fluorescence signal-to-dose ratio (FSDR) and fluorescence-normalized scan time (FNST) were used as metrics to assess results. Results: Calculated XRF/scatter spectra for 1-mm Pb and 0.9-mm Sn filters matched (r ≥ 0.996) experimental measurements. Calculated spectra representing additional filtration for both filter materials showed that the spectral hardening improved the FSDR at the expense of requiring a much longer FNST. In general, using Sn instead of Pb, at a given filter thickness, allowed an increase of up to 20% in FSDR, more prominent gold XRF peaks, and up to an order of magnitude decrease in FNST. Simulations using quasimonochromatic spectra suggested that increasing source x-ray energy, in the

  4. pH Dependence of Chlorophyll States, Protein Structures and Function of the PSII Membranes

    Institute of Scientific and Technical Information of China (English)

    李冬海; 阮翔; 许强; 王可玢; 公衍道; 匡廷云; 张秀芳; 赵南明

    2003-01-01

    The effect of varying pH on the photosystem II (PSII) membrane was studied using absorption and steady-state fluorescence spectroscopy, and using a variable fluorescence technique.pH variations induced significant changes in the chlorophyll states of the PSII membrane, but no effect was seen on the chlorophyll fluorescence parameter F′v/F′m.For acidic pH conditions, protein structures of the PSII membrane were slightly altered, whilst at alkaline pH levels, large changes in the protein structure of the PSII membrane were detected.The results indicate that the microenvironment around Cys in the PSII membrane is very susceptible to alkaline pH conditions, and that in the acid (4≤pH7) regions, pH variation has no effect on the protein structures of the PSII reaction center (RC).

  5. 基于低空成像高光谱系统探测植被日光诱导叶绿素荧光%Remote Sensing of Chlorophyll Fluorescence at Airborne Level Based on Unmanned Airship Platform and Hyperspectral Sensor

    Institute of Scientific and Technical Information of China (English)

    杨沛琦; 刘志刚; 倪卓娅; 王冉; 王庆山

    2013-01-01

    The solar-induced chlorophyll fluorescence (ChlF) has a close relationship with photosynthetic and is considered as a probe of plant photosynthetic activity .In this study ,an airborne fluorescence detecting system was constructed by using a hyper-spectral imager on board an unmanned airship .Both Fraunhofer Line Discriminator (FLD) and 3FLD used to extract ChlF re-quire the incident solar irradiance ,which is always difficult to receive at airborne level .Alternative FLD (aFLD) can overcome the problem by selecting non-fluorescent emitter in the image .However ,aFLD is based on the assumption that reflectance is i-dentical around the Fraunhofer line ,which is not realistic .A new method ,a3FLD ,is proposed ,which assumes that reflectance varies linearly with the wavelength around Fraunhofer line .The result of simulated data shows that ChlF retrieval error of a3FLD is significantly lower than that of aFLD when vegetation reflectance varies near the Fraunhofer line .The results of hyper-spectral remote sensing data with the airborne fluorescence detecting system show that the relative values of retrieved ChlF of 5 kinds of plants extracted by both aFLD and a3FLD are consistent with vegetation growth stage and the ground-level ChlF .The ChlF values of aFLD are about 15% greater than a3FLD .In addition ,using aFLD ,some non-fluorescent objects have considera-ble ChlF value ,while a3FLD can effectively overcome the problem .%植被叶绿素荧光与光合作用关系密切,被认为是光合作用的有效探针。该研究利用成像高光谱传感器和无人飞艇构建了一套适用于低空叶绿素荧光探测的系统。针对低空叶绿素荧光探测中,太阳下行辐射光谱难以获取的情况,基于已有的aFLD方法,提出一种新的叶绿素荧光提取方法a3FLD,该方法利用了非荧光发射体,且考虑植被反射率在夫琅和费线附近的变化。通过模拟数据以及实测数据对两种提取结果进行了比较。

  6. Decadal Changes in Global Ocean Chlorophyll

    Science.gov (United States)

    Gregg, Watson W.; Conkright, Margarita E.; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    The global ocean chlorophyll archive produced by the Coastal Zone Color Scanner (CZCS) was revised using compatible algorithms with the Sea-viewing Wide Field-of-view Sensor (SeaWIFS), and both were blended with in situ data. This methodology permitted a quantitative comparison of decadal changes in global ocean chlorophyll from the CZCS (1979-1986) and SeaWiFS (Sep. 1997-Dec. 2000) records. Global seasonal means of ocean chlorophyll decreased over the two observational segments, by 8% in winter to 16% in autumn. Chlorophyll in the high latitudes was responsible for most of the decadal change. Conversely, chlorophyll concentrations in the low latitudes increased. The differences and similarities of the two data records provide evidence of how the Earth's climate may be changing and how ocean biota respond. Furthermore, the results have implications for the ocean carbon cycle.

  7. Effects of shading on the photosynthetic characteristics and chlorophyll fluorescence of the endangered plantYunnanopilia longistaminata%遮荫对濒危植物甜菜树光合生理和叶绿素荧光特性的影响

    Institute of Scientific and Technical Information of China (English)

    杨冠松; 张爱丽; 申仕康; 吴春妍; 王跃华;