Journal articles: 'Chlorophyle a fluorescence'

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Kummerová, M., and L. Váňová. "Chlorophyll fluorescence as an indicator of fluoranthene phototoxicity." Plant, Soil and Environment 53, No. 10 (January 7, 2008): 430–36. http://dx.doi.org/10.17221/2197-pse.

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The effect of the short-time exposure (12, 24 and 48 h) of increasing concentration (0.1, 1 and 10 mg/l) of intact (FLT) and photo-modified (phFLT) fluoranthene on the chlorophyll fluorescence parameters (F0, FV/FM and ΦII) in pea plants (Pisum sativum L. cv. Lantra) was investigated. Plants took up both forms of fluoranthene by two different ways, via roots or via leaves. The obtained results demonstrated a significant increase in F0 and decrease in FV/FM and ΦII in plants treated by 1 and 10 mg/l FLT and phFLT. An earlier response to presence of FLT and phFLT in the environment was demonstrated by application on cut leaves. The primary processes of photosynthesis were not significantly influenced by short-time phFLT treatment.

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Brody, S. S. "The Position of Carotene in the D-1/D-2 Sub-Core Complex of Photosystem II." Zeitschrift für Naturforschung C 43, no. 3-4 (April 1, 1988): 226–30. http://dx.doi.org/10.1515/znc-1988-3-413.

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When the sub-core complex of photosystem II, D1/D2, is irradiated at 436 or 415 nm (absorption by chlorophyll and pheophytin and β-carotene) or 540 nm (absorption primarily by pheophytin), the low temperature fluorescence spectrum has two maxima, at 685 and 674 nm. This shows the existence of at least two different fluorescent forms of chlorophyll (chlorophyll a and perhaps pheophytin a). When carotene is irradiated at 485 nm (absorption primarily by β-carotene), only fluorescence at 685 nm is observed: this indicates that carotene is transferring energy to only the long-wavelength form of chlorophyll in the D1/D2 sub-core complex. The band of carotene (at 485 nm) does not appear in the fluorescence excitation spectrum, measured at 674 nm. The position of the carotene molecule relative to each of the fluorescent forms of chlorophyll was determined from the excitation spectra of each of the fluorescence bands.

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Oh, Thomas, Jittiwat Sermsripong, and Barry W. Hicks. "Using Scuba for In Situ Determination of Chlorophyll Distributions in Corals by Underwater Near Infrared Fluorescence Imaging." Journal of Marine Science and Engineering 8, no. 1 (January 18, 2020): 53. http://dx.doi.org/10.3390/jmse8010053.

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Studies reporting quantitation and imaging of chlorophyll in corals using visible fluorescent emission in the red near 680 nm can suffer from competing emission from other red-emitting pigments. Here, we report a novel method of selectively imaging chlorophyll distributions in coral in situ using only the near infrared (NIR) fluorescence emission from chlorophyll. Commercially available equipment was assembled that allowed the sequential imaging of visible, visible-fluorescent, and NIR-fluorescent pigments on the same corals. The relative distributions of chlorophyll and fluorescent proteins (GFPs) were examined in numerous corals in the Caribbean Sea, the Egyptian Red Sea, the Indonesian Dampier Strait, and the Florida Keys. Below 2 m depth, solar induced NIR chlorophyll fluorescence can be imaged in daylight without external lighting, thus, it is much easier to do than visible fluorescence imaging done at night. The distributions of chlorophyll and GFPs are unique in every species examined, and while there are some tissues where both fluorophores are co-resident, often tissues are selectively enriched in only one of these fluorescent pigments. Although laboratory studies have clearly shown that GFPs can be photo-protective, their inability to prevent large scale bleaching events in situ may be due to their limited tissue distribution.

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Jay, Aicha El, Jean-Marc Ducruet, Jean-Claude Duval, and Jean Pierre Pelletier. "A high-sensitivity chlorophyll fluorescence assay for monitoring herbicide inhibition of photosystem II in the chlorophyte Selenastrum capricornutum: Comparison with effect on cell growth." Fundamental and Applied Limnology 140, no. 2 (September 25, 1997): 273–86. http://dx.doi.org/10.1127/archiv-hydrobiol/140/1997/273.

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Alexander, Troy A., Guan-Hong Gao, and Chieu D. Tran. "Development of a Novel Fluorimeter Based on Superluminescent Light-Emitting Diodes and Acousto-Optic Tunable Filter and its Application in the Determination of Chlorophylls a and b." Applied Spectroscopy 51, no. 11 (November 1997): 1603–6. http://dx.doi.org/10.1366/0003702971939578.

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A novel, compact, inexpensive fluorimeter that has high sensitivity and no moving parts has been developed by using super luminescent (bright-blue) light-emitting diodes (SLEDs) and an acousto-optic tunable filter (AOTF). In this instrument, the recently developed gallium nitride SLEDs were used in a counterpropagating configuration to provide excitation light. These SLEDs provide not only high intensity (several milliwatts) but also wide spectral bandwidth in the blue region (from 370 to 570 nm). The AOTF can be placed before the sample to facilitate the measurements of excitation spectra or after the sample for the emission spectra measurements. This fluorimeter is suitable for the sensitive and general fluorescent analysis of a variety of compounds. It has been used, as an example, for the sensitive and simultaneous determination of chlorophylls a and b. Detection limits of 2.30 × 10−9 and 1.10 × 10−9 M have been achieved for chlorophyll a and chlorophyll b, respectively. Index Headings: Superluminescent light-emitting diode; Acousto-optic tunable filter; Fluorescence; Chlorophyll.

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Chen, Min, Martin Schliep, Robert D. Willows, Zheng-Li Cai, Brett A. Neilan, and Hugo Scheer. "A Red-Shifted Chlorophyll: Fig. 1." Science 329, no. 5997 (August 19, 2010): 1318–19. http://dx.doi.org/10.1126/science.1191127.

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Chlorophylls are essential for light-harvesting and energy transduction in photosynthesis. Four chemically distinct varieties have been known for the past 60 years. Here we report isolation of a fifth, which we designate chlorophyll f. Its in vitro absorption (706 nanometers) and fluorescence (722 nanometers) maxima are red-shifted compared to all other chlorophylls from oxygenic phototrophs. On the basis of the optical, mass, and nuclear magnetic resonance spectra, we propose that chlorophyll f is [2-formyl]-chlorophyll a (C55H70O6N4Mg). This finding suggests that oxygenic photosynthesis can be extended further into the infrared region and may open associated bioenergy applications.

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Siebke, Katharina, and Marilyn C. Ball. "Non-destructive measurement of chlorophyll b:a ratios and identification of photosynthetic pathways in grasses by reflectance spectroscopy." Functional Plant Biology 36, no. 11 (2009): 857. http://dx.doi.org/10.1071/fp09201.

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Equations for non-destructive determination of chlorophyll b : a ratios in grasses were developed from reflectance spectra of intact leaves of barley (Hordeum vulgare L.) and two barley mutants: clorina f2, which lacks chlorophyll b and clorina f104, which has a low chlorophyll b content. These plants enabled separation of effects of chlorophyll composition on reflectance spectra due to differential light absorption by chlorophylls a and b and to measure the effects of chlorophyll b on the contribution of fluorescence emitted by chlorophyll a to the reflectance spectra. Indices developed from these data were then tested on growth chamber-grown leaves from six C3 and 17 C4 grass species (7 NAD-ME and 10 NADP-ME subtypes). We used the chlorophyll b : a ratio because the data were less skewed than the chlorophyll a : b ratio. The best index for determination of the chlorophyll b : a ratio utilised wavelengths affected by chlorophyll absorbance: [R626 – 0.5 (R603 + R647)]/[R552– R626]. The chlorophyll b : a ratio was significantly lower in the C4 than C3 grasses, but was not sufficient in itself to separate these two functional groups. However, because of differences in fluorescence characteristics, C3 and C4 species could be distinguished by an index based on wavelengths affected by chlorophyll fluorescence: [R696 to 709/R545 to 567].

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De Mesquita Alves, Jackson, Alex Serafim De Lima, Francisco Romário Andrade Figueiredo, Toshik Iarley Da Silva, Lourival Ferreira Cavalcante, Francisco De Oliveira Mesquita, Evandro Franklin De Mesquita, and Cesenildo De Figueiredo Suassuna. "Chlorophyll a fluorescence and development of zucchini plants under nitrogen and silicon fertilization." Agronomía Colombiana 38, no. 1 (January 1, 2020): 45–52. http://dx.doi.org/10.15446/agron.colomb.v38n1.79172.

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Zucchini (Cucurbita pepo L.) has a great economic and productive potential in the semi-arid region of Brazil, due to the wide acceptance by consumers and quick financial return. The nitrate (NO3-) assimilation process in C3 plants such as zucchini is related to photorespiration, and Si accumulated near the stomata reduces the transpiration rate, making the photosynthesis cycle more efficient. The objective of this study was to evaluate the interaction between nitrogen and silicon fertilization ongrowth, chlorophyll index, and chlorophyll a fluorescence of zucchini plants. The treatments were distributed in a split-plot scheme in a randomized block design with three replicates. The plot was arranged by silicon levels (0 and 6 g/plant) and the subplots constituted by five nitrogen levels (30, 60, 90, 120 and 150 kg ha-1). Leaf, stem and total dry masses, chlorophylla, chlorophyll b, total chlorophyll, chlorophyll a/b ratio and chlorophyll a fluorescence were evaluated. The highest dry matter productions in zucchini were obtained in treatments without Si. Si and N application together positively influences the chlorophyll a/b ratio of zucchini plants. The interaction between Si and N positively influences the maximum fluorescence, variable fluorescence and quantum yield of photosystemII of zucchini plants.

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Gruszecki, Wiesław I., Konka Veeranjaneyulu, and Roger M. Leblanc. "Qualitative changes in the fluorescence spectra of intact pea leaves after photoinhibition." Biochemistry and Cell Biology 69, no. 5-6 (May 1, 1991): 399–403. http://dx.doi.org/10.1139/o91-060.

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In high light (1400 W m−2) treated, intact pea leaves, a decrease in the ratio of fluorescence emission at 685 to 730 nm and an increase in fluorescence intensity between 500 and 600 nm were observed. Furthermore, photoacoustically monitored heat emission increased slightly, and O2 evolution decreased significantly. These findings are interpreted as effects of a photoprotective mechanism separating the carotenoid pool from the chlorophylls. This is supported by fluorescence excitation measurements and the results of a study on the reversibility of the process.Key words: chlorophyll fluorescence, carotenoid fluorescence, photoinhibition, photosynthesis, energy transfer.

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Khanizadeh, Shahrokh, and Jennifer Deell. "Chlorophyll Fluorescence." Small Fruits Review 1, no. 3 (July 6, 2001): 61–67. http://dx.doi.org/10.1300/j301v01n03_06.

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11

García-Pomar, J. L., and R. Gutierrez-Contrera. "Red fluorescence of chlorophyll." Optica Pura y Aplicada 48, no. 2 (June 30, 2015): 93–97. http://dx.doi.org/10.7149/opa.48.2.93.

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12

Gruszecki, Wieslaw I., and Zbigniew Krupa. "Changes of Excitation Spectra of in vivo Chlorophyll Fluorescence during Induction of Photosynthesis." Zeitschrift für Naturforschung C 48, no. 1-2 (February 1, 1993): 46–51. http://dx.doi.org/10.1515/znc-1993-1-209.

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Excitation spectra of chlorophyll fluorescence from intact rye leaves were registered at different steps of the induction of photosynthesis after dark adaptation. Analysis of these spectra indicates that at least two processes related to spectroscopic features are responsible for a fluorescence quenching. The first one, active during the first 100 s of illumination, was interpreted to consists in an overall decrease of the fluorescence quantum yield of antenna pigments and chlorophylls, in particular close to the reaction centers. The second type of a fluorescence decrease (between 100 s and 300 s of illumination) was found to be in large extent related to decrease of the rate of an excitation energy transfer between accessory xanthophyll pigments and chlorophylls emitting fluorescence. This latter molecular mechanism is discussed as being related to violaxanthin availability to de-epoxidation in the xanthophyll cycle.

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13

Jockusch, Steffen, Nicholas J. Turro, Srinivas Banala, and Bernhard Kräutler. "Photochemical studies of a fluorescent chlorophyll catabolite – source of bright blue fluorescence in plant tissue and efficient sensitizer of singlet oxygen." Photochem. Photobiol. Sci. 13, no. 2 (2014): 407–11. http://dx.doi.org/10.1039/c3pp50392e.

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14

Etinski, Mihajlo, Milena Petkovic, and Miroslav Ristic. "A study of the low-lying singlet and triplet electronic states of chlorophyll A and B." Journal of the Serbian Chemical Society 78, no. 11 (2013): 1775–87. http://dx.doi.org/10.2298/jsc130806096e.

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Chlorophylls have been extensively investigated both experimentally and theoretically owing to the fact that they are essential for photosynthesis. We have studied two forms of chlorophyll, chlorophyll a and chlorophyll b, by means of density functional theory. Optimization of S0, S1 and T1 states was performed with the B3-LYP functional. The computed fluorescence lifetimes show good agreement with the available experimental data. The electronic adiabatic energies of S1 and T1 states are 2.09/2.12 and 1.19/1.29 eV for chlorophyll a and chlorophyll b respectively. We discussed the implications of this results on the triplet formation. Also, the calculated vertical ionization potentials shows good agreement with the experimental results.

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WOJCIECHOWSKA, Renata, Andrzej KALISZ, Agnieszka SĘKARA, Michał NOSEK, Stanisław CEBULA, Zbigniew MISZALSKI, Edward KUNICKI, and Aneta GRABOWSKA. "Alterations in Chlorophyll a Fluorescence and Pigments Concentration in the Leaves of Cauliflower and Broccoli Transplants Subjected to Chilling." Notulae Botanicae Horti Agrobotanici Cluj-Napoca 44, no. 1 (June 14, 2016): 17–24. http://dx.doi.org/10.15835/nbha44110251.

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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 investigatethe effects of chilling temperatures (6 and 10 °C) and the exposure length (1 or 2 weeks) on the photosynthetic apparatuscondition in 3-year experiment. Data were compared to control plants exposed to 14 °C for 1 and 2 weeks. The lowest valuesof maximum quantum efficiency of photosystem II (Fv/Fm) and the performance index (PI) were observed in cauliflowerchilled 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 negativeeffects of chilling on photosynthetic activity and chlorophyll content in broccoli leaves, the amount of carotenoids significantlyincreased in the broccoli chilled for 2 weeks in 6 °C. The chlorophyll a fluorescence indices and accelerated carotenoidssynthesis showed that broccoli had less vulnerable photosynthetic apparatus to stress-induced temperatures and more efficientprotection mechanisms in comparison to cauliflower transplants.

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Šebela, David, Julie Olejníčková, Anita Župčanová, and Radek Sotolář. "Response of grapevine leaves to Plasmopara viticola infection by means of measurement of reflectance and fluorescence signals." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 60, no. 8 (2012): 229–38. http://dx.doi.org/10.11118/actaun201260080229.

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Response of grapevine leaf tissue naturally infected byPlasmopara viticolain field was measured by means of chlorophyll fluorescence and reflectance signals. Three susceptible grapevine varieties (Cabernet Sauvignon, Pinot Blanc and Pinot Gris) were used in this study. Since the infection impairs photosynthetic activity, distribution of FV/FMparameter (maximum quantum yield of Photosystem II) over the leaf was effective to discriminate healthy and naturally infected leaf tissue. FV/FMwas reduced ~ 25% in all infected leaf parts. Infected leaf spots expressed significantly altered chlorophyll fluorescence induction kinetics expressing much slower electron transport rate both on donor and acceptor site of PSII. Vegetation reflectance indices followed the variations in pigment content after the fungal infection. R750/R700 (R2= 0.877) and CRI (carotenoid reflectance index; R2=0.735) were the most potent to follow changes in chlorophylls and carotenoids contents, respectively. Infected leaf tissue exhibited decrease in chlorophyll a (~50 %) as well as carotenoids (~70%). We conclude that combination of chlorophyll fluorescence and reflectance measurements can be used as an effective non-invasive tool for an early detection ofPlasmopara viticolain field as well as for estimation of the level of infection.

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Alexander Ingo, Linn, Košnarová Pavlína, Soukup Josef, and Gerhards Roland. "Detecting herbicide-resistant Apera spica-venti with a chlorophyll fluorescence agar test." Plant, Soil and Environment 64, No. 8 (August 1, 2018): 386–92. http://dx.doi.org/10.17221/110/2018-pse.

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Reliable tests on herbicide resistance are important for resistance management. Despite well-established greenhouse bioassays, faster and in-season screening methods would aid in more efficient resistance detection. The feasibility of a chlorophyll fluorescence agar-based test on herbicide resistance in Apera spica-venti L. was investigated. Herbicide resistant and sensitive A. spica-venti seedlings were transplanted into agar containing pinoxaden and pyroxsulam herbicides. Chlorophyll fluorescence was measured and the maximum quantum efficiency of photosystem II (Fv/Fm) was determined 48 h and 72 h after the transplantation to agar, respectively. The Fv/Fm values decreased with increasing herbicide concentration. Dose-response curves and respective ED50 values (herbicide concentration leading to 50% decrease of the Fv/Fm value) were calculated. However, each experiment repetition exhibited different sensitivities of the populations for both herbicides. In certain cases, resistant populations demonstrated similar Fv/Fm values as sensitive populations. Contrary to the findings in Alopecurus myosuroides Huds., discrimination of sensitive and resistant A. spica-venti populations was not feasible. An increased importance of the assessment time due to the herbicide concentrations calibrated for fast responses was assumed in this study.

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Kvíderová, Jana. "Rapid algal toxicity assay using variable chlorophyll fluorescence for Chlorella kessleri (chlorophyta)." Environmental Toxicology 25, no. 6 (November 18, 2010): 554–63. http://dx.doi.org/10.1002/tox.20516.

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Moser, Simone, Thomas Müller, Andreas Holzinger, Cornelius Lütz, Steffen Jockusch, Nicholas J. Turro, and Bernhard Kräutler. "Fluorescent chlorophyll catabolites in bananas light up blue halos of cell death." Proceedings of the National Academy of Sciences 106, no. 37 (September 8, 2009): 15538–43. http://dx.doi.org/10.1073/pnas.0908060106.

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Breakdown of chlorophyll is a major contributor to the diagnostic color changes in fall leaves, and in ripening apples and pears, where it commonly provides colorless, nonfluorescent tetrapyrroles. In contrast, in ripening bananas (Musa acuminata) chlorophylls fade to give unique fluorescent catabolites (FCCs), causing yellow bananas to glow blue, when observed under UV light. Here, we demonstrate the capacity of the blue fluorescent chlorophyll catabolites to signal symptoms of programmed cell death in a plant. We report on studies of bright blue luminescent rings on the peel of very ripe bananas, which arise as halos around necrotic areas in ‘senescence associated’ dark spots. These dark spots appear naturally on the peel of ripe bananas and occur in the vicinity of stomata. Wavelength, space, and time resolved fluorescence measurements allowed the luminescent areas to be monitored on whole bananas. Our studies revealed an accumulation of FCCs in luminescent rings, within senescing cells undergoing the transition to dead tissue, as was observable by morphological textural cellular changes. FCCs typically are short lived intermediates of chlorophyll breakdown. In some plants, FCCs are uniquely persistent, as is seen in bananas, and can thus be used as luminescent in vivo markers in tissue undergoing senescence. While FCCs still remain to be tested for their own hypothetical physiological role in plants, they may help fill the demand for specific endogenous molecular reporters in noninvasive assays of plant senescence. Thus, they allow for in vivo studies, which provide insights into critical stages preceding cell death.

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Hsu, Ban-Dar, and Kuen-Lin Leu. "A possible origin of the middle phase of polyphasic chlorophyll fluorescence transient." Functional Plant Biology 30, no. 5 (2003): 571. http://dx.doi.org/10.1071/fp03012.

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The rise of the chlorophyll fluorescence of a whole leaf as induced by high-intensity actinic light comprises three distinct phases, and is termed the O–J–I–P polyphasic rise. The initial rise (the O–J phase) was found to be the most sensitive to light intensity, being slower and smaller with decreasing irradiation. The leaf was also found to be transparent for chlorophyll fluorescence to a considerable extent, so that the fluorescence originating from deep inside the sample could still be detected. In contrast, the actinic light used to induce fluorescence was strongly absorbed by chlorophylls, so that a steep light gradient was created along the light path. The fluorescence transient of a leaf, thus, was always a mixture of the fluorescence from the surface of the sample as well as that from the inside of the sample, whose O–J phase is slower as it is induced by a weaker actinic light. We have provided evidence suggesting that, in an intact leaf, the middle phase of the measured polyphasic fluorescence transient (the J–I phase) might actually reflect the initial rise of the transient coming from the abaxial layer of the leaf. Moreover, if the polyphasic fluorescence transient is used as an analytical tool for accessing information on the photosynthetic activities of leaves, the factors of concentration and thickness of the sample must be taken into account. To obtain the 'true' fluorescence transient of a sample, both the chlorophyll concentration and thickness of the sample must be kept as low as possible.

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Helena, Hniličková, Hnilička František, Martinková Jaroslava, and Kraus Kamil. "Effects of salt stress on water status, photosynthesis and chlorophyll fluorescence of rocket." Plant, Soil and Environment 63, No. 8 (September 4, 2017): 362–67. http://dx.doi.org/10.17221/398/2017-pse.

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Salinity is a significant environmental factor affecting physiological processes in plants. This study monitors the effect of salt stress induced by the NaCl solution (0 – deionized water; 50, 100, 200, 300 mmol/L) in rocket (Eruca sativa (L.) Mill.) cv. Astro over the course of 50 days. Salt stress significantly affected the monitored parameters. The osmotic potential decreased with increasing NaCl concentrations, while relative water content decrease did not take place until 200 mmol/L NaCl. Compared to the control group, transpiration (E) decreased at the concentration of 50 mmol/L NaCl and stomatal conductance (gs) and net photosynthetic rate (Pn) decreased at 100 mmol/L NaCl. Further increase of salt concentrations did not affect Pn and no significant differences gs, E and substomatal concentration CO2 were measured between the concentrations of 200 and 300 mmol/L NaCl. A decrease of Fv/Fm took place from the concentration of 100 mmol/L NaCl, while differences between 200 and 300 mmol/L NaCl were also not significant. The obtained results therefore prove the tolerance of the E. sativa cv. Astro to salt stress.

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Jian, Yang, Du Lin, Gong Wei, Sun Jia, Shi Shuo, and Chen Biwu. "Application of the chlorophyll fluorescence ratio in evaluation of paddy rice nitrogen status." Plant, Soil and Environment 63, No. 9 (September 26, 2017): 396–401. http://dx.doi.org/10.17221/460/2017-pse.

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In this research, laser-induced fluorescence (LIF) technique combined with back-propagation neural network (BPNN) was employed to analyse different nitrogen (N) fertilization levels in paddy rice. Leaf fluorescence characteristics (FLCs) were measured by using the LIF system built in our laboratory and exhibited different FLCs with different nitrogen fertilization levels. The correlation between fluorescence intensity ratios (F685/F460, F735/F460 and F735/F685) and the dose of N fertilization was established and analysed. Then, the BPNN algorithm was utilized to validate that the different N fertilization levels can be classified based on the three FLCs. The overall identification accuracies of 2014 and 2015 were 90% and 92.5%, respectively. Experimental results demonstrated that the three FLCs with the help of multivariate analysis can be served as a helpful tool in the evaluation of paddy rice N fertilization levels. Besides, this study can also provide guidance for the selection of LIF Lidar channels in the following research.

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Rykaczewska, K., and D. Mańkowski. "The effect of physiological age of potato plants on chosen chlorophyll fluorescence parameters." Plant, Soil and Environment 61, No. 10 (June 6, 2016): 462–67. http://dx.doi.org/10.17221/474/2015-pse.

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LEE, MICHAEL R. F., MARK B. SCOTT, ANNETTE VEBERG-DAHL, PHIL R. EVANS, VINCE J. THEOBALD, FRANK LUNDBY, NIGEL D. SCOLLAN, and JENS-PETTER WOLD. "Potential of Chlorophyll-Rich Feed Ingredients To Improve Detection of Fecal Contamination in the Abattoir." Journal of Food Protection 76, no. 3 (March 1, 2013): 516–22. http://dx.doi.org/10.4315/0362-028x.jfp-12-353.

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The use of fecal fluorescence to improve detection of contamination of carcasses in the abattoir was previously reported. However, incidents of false negatives can result when animals are offered diets that contain little chlorophyll (e.g., concentrate). Here, we investigated the potential of incorporating a high-chlorophyll-containing feed ingredient (concentrated alfalfa extract; CAE) into the diets of sheep and cattle to improve fecal fluorescence intensity. The sheep experiment evaluated the fecal fluorescence of animals from pasture, when fed a concentrate–barley straw diet and when the concentrate diet incorporated CAE (100 g of dry matter a day). Fecal chlorophyll and metabolite content was highest on the pasture-fed animals and increased significantly over the concentrate diet when CAE was included. Subsequently fluorescent intensity was increased from 15,000 to 36,000 arbitrary units for concentrate and CAE–concentrate diets, respectively, compared with 59,000 for the pasture-fed animals. The cattle experiment investigated the potential of CAE to improve fluorescence of feces from a concentrate diet as well as a silage diet at two levels of incorporation (75 and 150 g CAE/kg of dry matter intake). This study also determined the fluorescence of digesta and carcass contamination in the abattoir on a subset of carcasses. In agreement with the sheep study, CAE significantly improved fluorescence of feces and digesta when added to a concentrate diet, but had little effect on improving fecal fluorescence from the silage-fed animals. This was thought to be related to greater chlorophyll degradation in the rumen or/and the dark nature of the silage feces acting as a quencher of emitted fluoresced light. Incorporating high-chlorophyll-containing plant ingredients into ruminant concentrate diets will improve detection of fecal contamination by reducing false-negative readings. However, they will have little effect on false-positive readings due to the range of wavelengths emitted by natural chlorophyll and its metabolites. Implications and potential solutions for this are discussed.

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Costa, D. S., J. Kodde, and S. P. C. Groot. "Chlorophyll fluorescence and X-ray analyses to characterise and improve paddy rice seed quality." Seed Science and Technology 42, no. 3 (December 1, 2014): 449–53. http://dx.doi.org/10.15258/sst.2014.42.3.11.

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Lu, Yuzhen, and Renfu Lu. "Detection of Chilling Injury in Pickling Cucumbers Using Dual-Band Chlorophyll Fluorescence Imaging." Foods 10, no. 5 (May 14, 2021): 1094. http://dx.doi.org/10.3390/foods10051094.

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Pickling cucumbers are susceptible to chilling injury (CI) during postharvest refrigerated storage, which would result in quality degradation and economic loss. It is, thus, desirable to remove the defective fruit before they are marketed as fresh products or processed into pickled products. Chlorophyll fluorescence is sensitive to CI in green fruits, because exposure to chilling temperatures can induce detectable alterations in chlorophylls of tissues. This study evaluated the feasibility of using a dual-band chlorophyll fluorescence imaging (CFI) technique for detecting CI-affected pickling cucumbers. Chlorophyll fluorescence images at 675 nm and 750 nm were acquired from pickling cucumbers under the excitation of ultraviolet-blue light. The raw images were processed for vignetting corrections through bi-dimensional empirical mode decomposition and subsequent image reconstruction. The fluorescence images were effective for ascertaining CI-affected tissues, which appeared as dark areas in the images. Support vector machine models were developed for classifying pickling cucumbers into two or three classes using the features extracted from the fluorescence images. Fusing the features of fluorescence images at 675 nm and 750 nm resulted in overall accuracies of 96.9% and 91.2% for two-class (normal and injured) and three-class (normal, mildly and severely injured) classification, respectively, which are statistically significantly better than those obtained using the features at a single wavelength, especially for the three-class classification. Furthermore, a subset of features, selected based on the neighborhood component feature selection technique, achieved the highest accuracies of 97.4% and 91.3% for the two-class and three-class classification, respectively. This study demonstrated that dual-band CFI is an effective modality for CI detection in pickling cucumbers.

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Donaldson, Lloyd. "Autofluorescence in Plants." Molecules 25, no. 10 (May 21, 2020): 2393. http://dx.doi.org/10.3390/molecules25102393.

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Plants contain abundant autofluorescent molecules that can be used for biochemical, physiological, or imaging studies. The two most studied molecules are chlorophyll (orange/red fluorescence) and lignin (blue/green fluorescence). Chlorophyll fluorescence is used to measure the physiological state of plants using handheld devices that can measure photosynthesis, linear electron flux, and CO2 assimilation by directly scanning leaves, or by using reconnaissance imaging from a drone, an aircraft or a satellite. Lignin fluorescence can be used in imaging studies of wood for phenotyping of genetic variants in order to evaluate reaction wood formation, assess chemical modification of wood, and study fundamental cell wall properties using Förster Resonant Energy Transfer (FRET) and other methods. Many other fluorescent molecules have been characterized both within the protoplast and as components of cell walls. Such molecules have fluorescence emissions across the visible spectrum and can potentially be differentiated by spectral imaging or by evaluating their response to change in pH (ferulates) or chemicals such as Naturstoff reagent (flavonoids). Induced autofluorescence using glutaraldehyde fixation has been used to enable imaging of proteins/organelles in the cell protoplast and to allow fluorescence imaging of fungal mycelium.

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Li, Tingchun, Huaying Yang, Yan Lu, Qing Dong, Guihu Liu, Feng Chen, and Yingbing Zhou. "Comparative transcriptome analysis of differentially expressed genes related to the physiological changes of yellow-green leaf mutant of maize." PeerJ 9 (February 16, 2021): e10567. http://dx.doi.org/10.7717/peerj.10567.

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Chlorophylls, green pigments in chloroplasts, are essential for photosynthesis. Reduction in chlorophyll content may result in retarded growth, dwarfism, and sterility. In this study, a yellow-green leaf mutant of maize, indicative of abnormity in chlorophyll content, was identified. The physiological parameters of this mutant were measured. Next, global gene expression of this mutant was determined using transcriptome analysis and compared to that of wild-type maize plants. The yellow-green leaf mutant of maize was found to contain lower contents of chlorophyll a, chlorophyll b and carotenoid compounds. It contained fewer active PSII centers and displayed lower values of original chlorophyll fluorescence parameters than the wild-type plants. The real-time fluorescence yield, the electron transport rate, and the net photosynthetic rate of the mutant plants showed reduction as well. In contrast, the maximum photochemical quantum yield of PSII of the mutant plants was similar to that of the wild-type plants. Comparative transcriptome analysis of the mutant plants and wild-type plants led to the identification of differentially expressed 1,122 genes, of which 536 genes were up-regulated and 586 genes down-regulated in the mutant. Five genes in the chlorophyll metabolism pathway, nine genes in the tricarboxylic acid cycle and seven genes related to the conversion of sucrose to starch displayed down-regulated expression. In contrast, genes encoding a photosystem II reaction center PsbP family protein and the PGR5-like protein 1A (PGRL1A) exhibited increased transcript abundance.

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Posudin, Yu, Mitsunobu Kamiya, Akio Murakami, and Hiroshi Kawai. "Effect of light of different intensity on chlorophyll fluorescence of Ulva pertusa Kjellman (Chlorophyta)." International Journal on Algae 6, no. 3 (2004): 235–50. http://dx.doi.org/10.1615/interjalgae.v6.i3.30.

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Orekhova, Alla, Miloš Barták, Aleyna Özkar, and Josef Elster. "The effect of shock freezing on physiological properties and consequent growth of Antarctic filamentous (Stigeoclonium sp.) and coccal alga (Diplosphaera chodatii) on agar plates." Czech Polar Reports 9, no. 1 (January 1, 2019): 37–48. http://dx.doi.org/10.5817/cpr2019-1-4.

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In this study, we investigated the effects of shock freezing on physiological properties and consequent growth of in the Antarctic alga Stigeoclonium sp. and comparative coccal alga Diplosphaera chodatii on agar plates. Culture of algae grown in liquid medium were used to study subzero temperatures on the species resistance to shock freezing. Then, microalgae were frozen in liquid nitrogen and inoculated on BBM agar after thawing. Physiological status of algae was evaluated by chlorophyll fluorescence parameters during 28 days. The results showed that interspecific differences existed in their tolerance to shock freezing, as well as their consequent growth rate on agars. Direct effects of freezing in liquid nitrogen was demonstrated in chlorophyll fluorescence parameters recorded immediately after thawing the samples (in liquid medium). In spite of the fact that majority of cells was destroyed by shock freezing, the potential of photochemical processes in PS II (FV/FM) remained constant in D. chodatii. It may indicate high resistance of the species to freezing/thawing cycles and a capability of the surviving cells, core chlorophylls in PS II respectively, to perform photosynthetic processes related to PS II. Contrastingly, Stigeoclonium sp. showed a shock freezing-dependent decrease in FV/FM. When shock-frozen, thawed and inoculated on agar plates, the culture of D. chodatii, and Stigeoclonium sp. showed cultivation time-dependent increase in chlorophyll fluorescence parameters (FV/FM, FS).

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Kosson, Ryszard. "The effect of storage temperature of cucumber fruit on chlorophyll fluorescence." Acta Agrobotanica 53, no. 1 (2013): 57–64. http://dx.doi.org/10.5586/aa.2000.007.

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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 was decTeasing when cucumbers were stored at temperature lower or higher than optimum level. The chlorophyll fluorescence measurements can be helpful for determination of appropriate temperature parameters of cucumber storage.

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Jalink, H., A. Frandas, R. van der Schoor, and J. B. Bino. "Chlorophyll fluorescence of the testa of Brassica oleracea seeds as an indicator of seed maturity and seed quality." Scientia Agricola 55, spe (1998): 88–93. http://dx.doi.org/10.1590/s0103-90161998000500016.

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Chlorophyll fluorescence of the testa of seeds is proposed as a non-invasive method for the determination of maturity and quality of seeds. In this study cabbage seeds (Brassica oleracea) were sorted individually based on the chlorophyll fluorescence signals into four subsamples labeled with respect to their chlorophyll fluorescence signal (low, medium, high and very high). The results show that the magnitude of the chlorophyll fluorescence signal was inversely related to the quality of the seeds, expressed as germination %, normal seedling %, germination rate (T50) and uniformity of germination (T75-T25). The seed lot could be improved from 90 to 97% normal seedlings by sorting out 13% of the seeds with very high chlorophyll fluorescence signals. Advantages of the chlorophyll fluorescence method for sorting seeds are the high sensitivity, the method being fully non-destructive, the high speed at which the fluorescence is generated and measured and the specificity for only chlorophyll. Other pigments or substances which can influence seed colour but do not fluoresce at the specific wavelengths of excitation and emission of chlorophyll, will not contribute to the fluorescence signal. These characteristics make chlorophyll fluorescence highly suitable as a new sorting technique.

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Ruth, B. "Direct observation of herbicide action in algae using 10 µs resolved chlorophyll fluorescence induction kinetics." Archiv für Hydrobiologie 131, no. 3 (October 12, 1994): 297–308. http://dx.doi.org/10.1127/archiv-hydrobiol/131/1994/297.

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Köhl, Karin, Takayuki Tohge, and Mark Aurel Schöttler. "Performance of Arabidopsis thaliana under different light qualities: comparison of light-emitting diodes to fluorescent lamp." Functional Plant Biology 44, no. 7 (2017): 727. http://dx.doi.org/10.1071/fp17051.

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For precise phenotyping, Arabidopsis thaliana (L.) Heynh. is grown under controlled conditions with fluorescent lamps as the predominant light source. Replacement by systems based on light emitting diodes (LED) could improve energy efficiency and stability of light quality and intensity. To determine whether this affects the reproducibility of results obtained under fluorescent lamps, four Arabidopsis accessions and a phytochrome mutant were grown and phenotyped under two different LED types or under fluorescent lamps. All genotypes had significantly higher rosette weight and seed mass and developed faster under LED light than under fluorescent lamps. However, differences between genotypes were reproducible independent of the light source. Chlorophyll content, photosynthetic complex accumulation and light response curves of chlorophyll fluorescence parameters were indistinguishable under LED and fluorescent light. Principal component analysis of leaf metabolite concentrations revealed that the effect of a change from fluorescent light to LED light was small compared with the diurnal effect, which explains 74% of the variance and the age effect during vegetative growth (12%). Altogether, the replacement of fluorescent lamps by LED allowed Arabidopsis cultivation and reproduction of results obtained under fluorescent light.

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Joža, Ana V., Dragan Z. Stupar, Jovan S. Bajić, Bojan M. Dakić, Zoran Mijatović, Miloš P. Slankamenac, and Miloš B. Živanov. "An End-Type Fiber-Optic UV Sensor Covered with Mixture of Two UV Sensitive Materials." Key Engineering Materials 543 (March 2013): 265–68. http://dx.doi.org/10.4028/www.scientific.net/kem.543.265.

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An end-type fiber-optic UV sensor based on the principle of fluorescence is proposed and demonstrated. The sensor is made of large-core plastic optical fiber with one end covered with mixture of hot melt adhesive and small amount of chlorophyll. As sources of ultraviolet radiation solar simulator and UV lamp are used. Spectra on the sensor output are measured with spectrometer and compared for different UV light sources. Both hot melt adhesive and chlorophyll reacted to UV radiation. The peaks of fluorescent emission are obtained in visible spectrum in range of blue wavelengths (for hot melt adhesive) and in range of red wavelengths (for chlorophyll), which makes this sensor configuration a good solution for signal multiplexing.

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Calatayud, A., M. J. Sanz, E. Calvo, E. Barreno, and S. del Valle-Tascon. "Chlorophyll A Fluorescence and Chlorophyll Content in Parmelia Quercina Thalli from a Polluted Region of Northern Castellon (Spain)." Lichenologist 28, no. 1 (January 1996): 49–65. http://dx.doi.org/10.1006/lich.1996.0005.

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AbstractMeasurements of modulated chlorophyll a fluorescence emission and chlorophyll content were made in thalli of Parmelia quercina collected from northern Castellon(Spain). Althoug high air pollution concentrations have been measured in this area, the ratio of variable to maximal fluorescence is unaffected. Following dark-adaptation, the response to irradiance of chlorophyll fluorescence was examined. With respect to control samples, thalli collected in northern Castellon consistently showed differences in fluorescence quenching, the efficiency of excitation energy capture and quenching of basal fluorescence. However, the quantum ield of photochemistry and non-cyclic electron flow were not affected. The changes in chlorophyll fluorescence parameters were observed in the absence of both visual injuries and decrease in chlorophyll content. The results are discussed with regard to the possible role of environmental stress in chlorophyll fluorescence yield.

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Hunt, E. Raymond, James E. McMurtrey, Amy E. Parker Williams, and Lawrence A. Corp. "Spectral characteristics of leafy spurge (Euphorbia esula) leaves and flower bracts." Weed Science 52, no. 4 (August 2004): 492–97. http://dx.doi.org/10.1614/ws-03-132r.

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Leafy spurge can be detected during flowering with either aerial photography or hyperspectral remote sensing because of the distinctive yellow-green color of the flower bracts. The spectral characteristics of flower bracts and leaves were compared with pigment concentrations to determine the physiological basis of the remote sensing signature. Compared with leaves of leafy spurge, flower bracts had lower reflectance at blue wavelengths (400 to 500 nm), greater reflectance at green, yellow, and orange wavelengths (525 to 650 nm), and approximately equal reflectances at 680 nm (red) and at near-infrared wavelengths (725 to 850 nm). Pigments from leaves and flower bracts were extracted in dimethyl sulfoxide, and the pigment concentrations were determined spectrophotometrically. Carotenoid pigments were identified using high-performance liquid chromatography. Flower bracts had 84% less chlorophylla, 82% less chlorophyllb, and 44% less total carotenoids than leaves, thus absorptance by the flower bracts should be less and the reflectance should be greater at blue and red wavelengths. The carotenoid to chlorophyll ratio of the flower bracts was approximately 1:1, explaining the hue of the flower bracts but not the value of reflectance. The primary carotenoids were lutein, β-carotene, and β-cryptoxanthin in a 3.7:1.5:1 ratio for flower bracts and in a 4.8:1.3:1 ratio for leaves, respectively. There was 10.2 μg g−1fresh weight of colorless phytofluene present in the flower bracts and none in the leaves. The fluorescence spectrum indicated high blue, red, and far-red emission for leaves compared with flower bracts. Fluorescent emissions from leaves may contribute to the higher apparent leaf reflectance in the blue and red wavelength regions. The spectral characteristics of leafy spurge are important for constructing a well-documented spectral library that could be used with hyperspectral remote sensing.

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TAKAYAMA, Kotaro, and Hiroshige NISHINA. "Chlorophyll Fluorescence Imaging of the Chlorophyll Fluorescence Induction Phenomenon for Plant Health Monitoring." Environment Control in Biology 47, no. 2 (2009): 101–9. http://dx.doi.org/10.2525/ecb.47.101.

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Ji, Jian Wei, Ming Hu Xu, and Zheng Ming Li. "Research and Application on Chlorophyll Fluorescence On-Line Monitoring Technology." Advanced Materials Research 139-141 (October 2010): 2550–55. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.2550.

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Chlorophyll fluorescence (CF) has become a powerful tool in plant photosynthesis research and stress detection, considered a rapid, highly sensitive and non-invasive probe of photosynthetic activity. With the rapid development of computer technology and sensor technology for weak signal, recently much attention has been paid to chlorophyll fluorescence on-line monitoring for estimation of plant photosynthesis. This paper analyzes the fundamental principle of chlorophyll fluorescence on-line monitoring technology, introduces a new measurement and control system for chlorophyll fluorescence, which bases on MINIPAM, using light-emitting diode (LED) excitation by means of measuring the fluorescence parameters, and introduces application of active fluorescence measurement and passive fluorescence measurement in the study of the biological information monitoring in plant photosynthesis. Finally, the future development trends, the prospect and the difficulties of chlorophyll fluorescence on-line monitoring technology are discussed.

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Trstenjak, Tomo, Antunovic Dunic, Selma Mlinaric, Lidija Begovic, Marin Skoro, Vera Cesar, and Hrvoje Lepedus. "Anatomy, chlorophyll content and photosynthetic performance in current-year and previous-year Aleppo pine (Pinus halepensis Mill.) needles." Botanica Serbica 44, no. 1 (2020): 61–69. http://dx.doi.org/10.2298/botserb2001061t.

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Aleppo pine (Pinus halepensis) is a widespread Mediterranean woody species. Needles usually fall off the tree after the second year, which can be the reason for substantial crown defoliation under extreme environmental stress. The aim of the present investigation was to compare the anatomy, chlorophyll content and photosynthetic performance in current-year (CY) and previous-year (PY) Aleppo pine needles. Chlorophyll concentrations were determined spectrophotometrically, while photosynthetic performance was determined by measuring the increase in chlorophyll a fluorescence (the JIP test). The obtained results revealed that concentrations of chlorophylls a and b were almost twice as great in PY needles as in CY ones. The chlorophyll a to b ratio and values of the maximum quantum yield of photosystem II (Fv/Fm) showed no statistically significant difference between CY and PY needles. However, the performance index (PIABS) was significantly higher in CY needles compared to PY ones. Analysis of PIABS components revealed that CY needles had increased electron transport beyond the primary electron acceptor, QA -, which was associated with a lower value of variable fluorescence at 2 ms (VJ) in comparison with PY needles. Also, some differences were observed in needle anatomy. Current-year needles had an increased proportion of mesophyll tissue, together with decreased proportions of vascular cylinder and resin duct areas. Also, many more starch grains were present in PY than in CY needles. Based on the presented results, it can be concluded that despite considerably lower chlorophyll content, CY needles exhibited photosynthetic performance better than that of older needles, which is an unusual phenomenon in woody species.

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Marečková, Michaela, and Miloš Barták. "Effects of short-term low temperature stress on chlorophyll fluorescence transients in Antarctic lichen species." Czech Polar Reports 6, no. 1 (January 1, 2016): 54–65. http://dx.doi.org/10.5817/cpr2016-1-6.

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Chlorophyll fluorescence is an effective tool for investigating characteristics of any photosynthesizing organisms and its responses due to different stressors. Here, we have studied a short-term temperature response on two Antarctic green algal lichen species: Umbilicaria antarctica, and Physconia muscigena. We measured slow chlorophyll fluorescence transients in the species during slow a cooling of thallus temperature from 20°C to 5°C with a 10 min. acclimation at each temperature in dark. The measurements were supplemented with saturation pulses for the analysis of chlorophyll fluorescence parameters: maximum yield of PS II photochemistry (FV/FM), effective quantum yield of PS II photochemistry (FPSII) and non-photochemical quenching (NPQ). In response to decreasing thallus temperature, we observed species-specific changes in chlorophyll fluorescence levels P, S, M, T reached during chlorophyll fluorescence transient as well as in the shape of the chlorophyll fluorescence transients. With a decrease in temperature, the time at which M and T chlorophyll fluorescence levels were reached, increased. These changes were attributed to redox state of plastoquinon pool, changes in Calvin-Benson cycle activity, non-photochemical quenching components, state transition in particular. In this study, we present some chlorophyll fluorescence ratios (P/M, M/T, P/T) and chlorophyll fluorescence increase rates (FR1, i.e. O to P, and FR2 - i.e. S to M) as the parameters reflecting direct temperature effects on chloroplastic apparatus of lichen alga sensitively. We proposed that species-specific changes in the slow phase of chlorophyll fluorescence transients could be potentially used as indicators of low temperature effects in photosynthetic apparatus of lichen algal photobionts. Interspecific differences in response to low temperature might be evaluated using the approach as well.

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Beneragama, Chalinda Koshitha, B. L. H. N. Balasooriya, and T. M. R. S. Perera. "Use of O-J-I-P Chlorophyll Fluorescence Transients to Probe Multiple Effects of UV-C Radiation on the Photosynthetic Apparatus of Euglena." International Journal of Applied Sciences and Biotechnology 2, no. 4 (December 25, 2014): 553–58. http://dx.doi.org/10.3126/ijasbt.v2i4.10510.

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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. DOI: http://dx.doi.org/10.3126/ijasbt.v2i4.10510 Int J Appl Sci Biotechnol, Vol. 2(4): 553-558

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Neveux, J., M. M. B. Tenório, S. Jacquet, J. P. Torréton, P. Douillet, S. Ouillon, and C. Dupouy. "Chlorophylls and Phycoerythrins as Markers of Environmental Forcings Including Cyclone Erica Effect (March 2003) on Phytoplankton in the Southwest Lagoon of New Caledonia and Oceanic Adjacent Area." International Journal of Oceanography 2009 (November 25, 2009): 1–19. http://dx.doi.org/10.1155/2009/232513.

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Spatio-temporal variations of chlorophylls and phycoerythrins, inferred by spectrofluorometric methods, were studied from April 2002 to June 2003 in the southwest lagoon and oceanic waters of New Caledonia. Trade winds blew 75% of the time and appeared as the main factor influencing surface Tchla (sum of monovinyl- and divinyl-chlorophyll a) variations in the ocean, near the barrier reef. Lagoon and oceanic waters differed in the composition of picoplanktonic cyanobacteria with a relative dominance of Prochlorococcus and high-phycourobilin Synechococcus in the ocean, and a relative dominance of high-phycoerythrobilin Synechococcus in the lagoon. Main pigment variations in the lagoon were associated with cyclone Erica in March 2003 and showed a 5-6 fold Tchla increase around Nouméa. The cyclone stimulated mainly diatom growth as indicated by the high chlorophyll (c1+c2)/chlorophyll a ratio and by the lowest values for the other pigment ratios. The relative importance of divinyl-chlorophyll a concentration and fluorescence excitation spectra of phycoerythrins appeared as useful tools for characterizing lagoon-ocean exchanges.

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Mohanty, N., and HY Yamamoto. "Mechanism of Non-Photochemical Chlorophyll Fluorescence Quenching. I. The Role of De-Epoxidised Xanthophylls and Sequestered Thylakoid Membrane Protons as Probed by Dibucaine." Functional Plant Biology 22, no. 2 (1995): 231. http://dx.doi.org/10.1071/pp9950231.

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Dibucaine reportedly inhibits the light-induced transthylakoid proton gradient of chloroplasts without inhibiting energy-dependent non-photochemical chlorophyll fluorescence quenching (Laasch, H. and Weis, E. (1989). Photosynthesis Research 22, 137-146). We show that dibucaine can inhibit fluorescence quenching, depending on the de-epoxidation state of the xanthophyll cycle. Whereas dibucaine (20-40 μM) had little effect on fluorescence quenching in pre-illuminated-type thylakoids (loaded with zeaxanthin and antheraxanthin), it strongly inhibited quenching in dark-adapted-type thylakoids (no preinduction of de-epoxidation). Dibucaine inhibited lumen acidification similarly in both types of thylakoids and also the induction of violaxanthin de-epoxidation in dark-adapted thylakoids. Thus dark-adapted and pre-illuminated thylakoids differed in de-epoxidation states and their suspectibility to dibucaine inhibition of fluorescence quenching corresponded to this difference. The mechanism of inhibition of de-epoxidation by dibucaine is unclear. It could be due to the inhibition of lumen acidification but an inhibition of the violaxanthin available for de-epoxidation is not excluded. High dibucaine concentrations inhibited de-epoxidase activity directly. Dibucaine inhibition of fluorescence quenching, however, is not limited to the inhibition of de-epoxidation. Small but clear effects on fluorescence quenching were present in thylakoids even with de-epoxidation preinduced. Moreover, thylakoids with preinduced de-epoxidation were more resistant to dibucaine inhibition of fluorescene quenching when poised by salt treatments for proton partitioning into membrane-sequestered domains than when poised for proton partitioning into delocalised domains. We conclude that non-photochemical quenching of chlorophyll fluorescence depends on both de-epoxidised xanthophylls and sequestered proton domains in the thylakoid membranes

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Peter, Carolin, Silke Thoms, Florian Koch, Franz Josef Sartoris, and Ulf Bickmeyer. "Sponge-derived Ageladine A affects the in vivo fluorescence emission spectra of microalgae." PLOS ONE 15, no. 11 (November 19, 2020): e0242464. http://dx.doi.org/10.1371/journal.pone.0242464.

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In several marine hosts of microalgae, fluorescent natural products may play an important role. While the ecological function of these compounds is not well understood, an interaction of these molecules with the photosynthesis of the symbionts has been suggested. In this study, the effect of Ageladine A (Ag A), a pH-dependent fluorophore found in sponges of the genus Agelas, on microalgal fluorescence was examined. The spectra showed an accumulation of Ag A within the cells, but with variable impacts on fluorescence. While in two Synechococcus strains, fluorescence of phycoerythrin increased significantly, the fluorescence of other Synechococcus strains was not affected. In four out of the five eukaryote species examined, chlorophyll a (Chl a) fluorescence intensity was modulated. In Tisochrysis lutea, for example, the position of the fluorescence emission maximum of Chl a was shifted. The variety of these effects of Ag A on microalgal fluorescence suggests that fluorophores derived from animals could play a crucial role in shaping the composition of marine host/symbiont systems.

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Petrovic, Sanja, Laura Tugulea, Dejan Markovic, and Marcela Barbanta-Patrascu. "Chlorophyll a and chlorophyllide a inside liposomes made of saturated and unsaturated lipids: A possible impact of the lipids microenvironment." Acta Periodica Technologica, no. 45 (2014): 215–27. http://dx.doi.org/10.2298/apt1445215p.

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The aim of this work was to examine a possible impact of liposomes lipids microenvironment, dictated by a chemical composition of the fatty acid branches, on incorporation and spectral behaviour of chlorophyll a, and its derivative, chlorophyllide a inside small liposomes. The liposomes with the incorporated chlorophylls were made of dimirystoyl phosphatidylcholine (DMPC), and unsaturated phosphatidylcholine (PC), containing significant fractions of unsaturated fatty acid moieties. In order to achieve the goal, both absorption and fluorescence polarization spectroscopy were applied, and the obtained data for the two incorporated pigments, which play a role of molecular sensors, were compared. In addition, quercetin, a well-known antioxidant, was used as the (chlorophylls) emission quencher, in order to estimate the type of environment sensed by the two pigments for the two liposomes that differ in chemical composition. The results, based primarily on fluorescence polarization data have shown that the emissions as well as the emission quenching were notably affected by a change in the lipids? chemical composition. That is an indirect proof of the impact of the liposomes microenvironment on the incorporated pigments? spectral behaviour.

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Lee, M. R. F., V. Theobald, J.-P. Wold, A. Veberg, F. Lundby, and M. Fraser. "Front face fluorescence spectroscopy as a rapid non-invasive tool for determining diet composition in free-ranging ruminants." Proceedings of the British Society of Animal Science 2009 (April 2009): 119. http://dx.doi.org/10.1017/s1752756200029586.

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Quantification of the diet consumed in free-ranging ruminants is essential to manipulate both agricultural performance and environmental impact. A common non-invasive approach for determining diet composition is based on using long-chain, saturated hydrocarbons (n-alkanes) as markers (Dove and Mayes, 1996). However a major drawback of using this approach is the time and related expense associated with extracting these compounds. Spectroscopic imaging is a rapidly evolving research area, with the potential to provide real-time solutions. Previous applications have shown its ability to detect chlorophyll and its breakdown products in faeces as markers of contamination in carcasses to reduce pathogen load entering the food chain (Ashby et al. 2003). Chlorophyll is ubiquitous in green plants and thus livestock diets. During digestion in the gut, chlorophyll is only partially degraded to coloured and fluorescent intermediates: phaeophytin, chlorophyllide, phaeophorbide and pyrophaeophorbide derivatives of chlorophylls a and b. It is these compounds that are detected by spectral imaging of the faeces, and comparisons of spectral wavelength profiles may provide comparative information about the animals’ diet.

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Mishra, Anamika, Josef Hájek, Tereza Tuháčková, Miloš Barták, and Kumud Bandhu Mishra. "Features of chlorophyll fluorescence transients can be used to investigate low temperature induced effects on photosystem II of algal lichens from polar regions ( Short Communication )." Czech Polar Reports 5, no. 1 (January 1, 2015): 99–111. http://dx.doi.org/10.5817/cpr2015-1-10.

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Chlorophyll fluorescence is an effective tool for investigating characteristics of any photosynthesizing organisms and its responses due to different stressors. Here, we have studied a short-term temperature response on three Antarctic green algal lichen species: Umbilicaria antarctica, Xanthoria elegans, and Rhizoplaca melanophtalma. We measured slow chlorophyll fluorescence transients in these Antarctic lichen species during slowely cooling of thallus temperature from 20°C to 5, 0 and -5°C with 20 minute acclimation at each temperature. The measurements were supplemented with saturation pulses for the analysis of chlorophyll fluorescence parameters: maximum yield of PS II photochemistry (FV/FM), effective quantum yield of PS II photochemistry (FPSII) and quenching parameters. In response to decreasing thallus temperature, we observed species-specific changes in chlorophyll fluorescence parameters as well as in the shape of the chlorophyll fluorescence transients. We propose that species-specific changes in the slow phase of chlorophyll fluorescence transients can be potentially used as indicators of freezing stress in photosynthetic apparatus of lichen algal photobionts.

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Ni, Zhuoya, Qifeng Lu, Hongyuan Huo, and Huili Zhang. "Estimation of Chlorophyll Fluorescence at Different Scales: A Review." Sensors 19, no. 13 (July 8, 2019): 3000. http://dx.doi.org/10.3390/s19133000.

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Measuring chlorophyll fluorescence is a direct and non-destructive way to monitor vegetation. In this paper, the fluorescence retrieval methods from multiple scales, ranging from near the ground to the use of space-borne sensors, are analyzed and summarized in detail. At the leaf-scale, the chlorophyll fluorescence is measured using active and passive technology. Active remote sensing technology uses a fluorimeter to measure the chlorophyll fluorescence, and passive remote sensing technology mainly depends on the sun-induced chlorophyll fluorescence filling in the Fraunhofer lines or oxygen absorptions bands. Based on these retrieval principles, many retrieval methods have been developed, including the radiance-based methods and the reflectance-based methods near the ground, as well as physically and statistically-based methods that make use of satellite data. The advantages and disadvantages of different approaches for sun-induced chlorophyll fluorescence retrieval are compared and the key issues of the current sun-induced chlorophyll fluorescence retrieval algorithms are discussed. Finally, conclusions and key problems are proposed for the future research.

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Mercure, Sarah-Amélie, Benoit Daoust, and Guy Samson. "Causal relationship between growth inhibition, accumulation of phenolic metabolites, and changes of UV-induced fluorescences in nitrogen-deficient barley plants." Canadian Journal of Botany 82, no. 6 (June 1, 2004): 815–21. http://dx.doi.org/10.1139/b04-062.

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Abstract:

UV-induced chlorophyll (ChlFUV) and blue-green (BGF) fluorescences emitted by leaves have been proposed as useful indicators of plant physiological status under stress conditions. In this report, we investigated the effects of nitrogen (N) deficiency on ChlFUV and BGF emissions of leaf sections in relation to plant growth inhibition and accumulation of phenolic metabolites in barley leaves. Plants in a growth chamber were supplied with one of five different NO3 concentrations (0.8, 1.6, 5.0, 8.0, or 16 mmol/L) for a 2-week period. Total fresh biomass decreased with decreasing N supply, whereas leaf content of soluble phenolic compounds increased. This increase in leaf phenolic compounds observed with limiting N supply was accompanied by large increases of the BGF intensity and BGF/ChlFUV ratio of leaf sections and, to a lower extent, by a decrease of the leaf epidermal transmittance of UV radiation (as estimated by the ratio of ChlF intensities induced by UV and blue excitation). Interestingly, we observed a negative correlation (r2 = 0.975) between fresh biomass of plants and BGF intensity of leaf sections. By interpreting, in a context of stress physiology, the changes of UV-induced fluorescences, our results support their potential use as a sensitive tool for the rapid assessment of a plant's nutrient status.Key words: blue-green fluorescence, chlorophyll fluorescence, flavonoids, growth inhibition, nitrogen deficiency, phenolic compounds.

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Journal articles on the topic 'Chlorophyle a fluorescence'

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