Simple determination of photosynthetic efficiency and photoinhibition of Dunalielia tertiolecta by saturating P" 3e fluorescence measurements

1994 ◽  
Vol 104 ◽  
pp. 187-196
Author(s):  
JW Hofstraat ◽  
JCH Peeters ◽  
JFH Snel ◽  
C Geel
Keyword(s):  
Photosynthetic Efficiency ◽  
Fluorescence Measurements

scholarly journals Fluorescent Orthopalladated Complexes of 4-Aryliden-5(4H)-Oxazolones from the Kaede Protein: Synthesis and Characterization

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1238
Author(s):  
Eduardo Laga ◽  
David Dalmau ◽  
Sofía Arregui ◽  
Olga Crespo ◽  
Ana I. Jimenez ◽  
...  
Keyword(s):  
Intramolecular Interactions ◽  
Ortho Position ◽  
Fluorescent Properties ◽  
Ancillary Ligands ◽  
X Ray ◽  
Mononuclear Complexes ◽  
Fluorescence Measurements ◽  
Anionic Ligands ◽  
Order Of Magnitude

The goal of the work reported here was to amplify the fluorescent properties of 4-aryliden-5(4H)-oxazolones by suppression of the hula-twist non-radiative deactivation pathway. This aim was achieved by simultaneous bonding of a Pd center to the N atom of the heterocycle and the ortho carbon of the arylidene ring. Two different 4-((Z)-arylidene)-2-((E)-styryl)-5(4H)-oxazolones, the structures of which are closely related to the chromophore of the Kaede protein and substituted at the 2- and 4-positions of the arylidene ring (1a OMe; 1b F), were used as starting materials. Oxazolones 1a and 1b were reacted with Pd(OAc)2 to give the corresponding dinuclear orthometalated palladium derivates 2a and 2b by regioselective C–H activation of the ortho-position of the arylidene ring. Reaction of 2a (2b) with LiCl promoted the metathesis of the bridging carboxylate by chloride ligands to afford dinuclear 3a (3b). Mononuclear complexes containing the orthopalladated oxazolone and a variety of ancillary ligands (acetylacetonate (4a, 4b), hydroxyquinolinate (5a), aminoquinoline (6a), bipyridine (7a), phenanthroline (8a)) were prepared from 3a or 3b through metathesis of anionic ligands or substitution of neutral weakly bonded ligands. All species were fully characterized and the X-ray determination of the molecular structure of 7a was carried out. This structure has strongly distorted ligands due to intramolecular interactions. Fluorescence measurements showed an increase in the quantum yield (QY) by up to one order of magnitude on comparing the free oxazolone (QY < 1%) with the palladated oxazolone (QY = 12% for 6a). This fact shows that the coordination of the oxazolone to the palladium efficiently suppresses the hula-twist deactivation pathway.

Monitoring of cold and light stress impact on photosynthesis by using the laser induced fluorescence transient (LIFT) approach

2010 ◽  
Vol 37 (5) ◽  
pp. 395 ◽  
Author(s):  
Roland Pieruschka ◽  
Denis Klimov ◽  
Zbigniew S. Kolber ◽  
Joseph A. Berry
Keyword(s):  
Photosynthetic Efficiency ◽  
Light Stress ◽  
Pulse Amplitude ◽  
Laser Induced Fluorescence ◽  
High Light Intensity ◽  
High Light ◽  
Persea Americana ◽  
Effective Quantum Yield ◽  
Fluorescence Transient ◽  
Fluorescence Measurements

Chlorophyll fluorescence measurements have been widely applied to quantify the photosynthetic efficiency of plants non-destructively. The most commonly used pulse amplitude modulated (PAM) technique provides a saturating light pulse, which is not practical at the canopy scale. We report here on a recently developed technique, laser induced fluorescence transient (LIFT), which is capable of remotely measuring the photosynthetic efficiency of selected leaves at a distance of up to 50 m. The LIFT approach correlated well with gas exchange measurements under laboratory conditions and was tested in a field experiment monitoring the combined effect of low temperatures and high light intensity on a variety of plants during the early winter in California. We observed a reduction in maximum and effective quantum yield in electron transport for Capsicum annuum L., Lycopersicon esculentum L. and Persea americana Mill. as the temperatures fell, while a grass community was not affected by combined low temperature and high light stress. The ability to make continuous, automatic and remote measurements of the photosynthetic efficiency of leaves with the LIFT system provides a new approach for studying and monitoring of stress effects on the canopy scale.

scholarly journals Simultaneous Determination of Trace Mefenamic Acid in Pharmaceutical Samples via Flow Injection Fluorometry

2020 ◽  
Vol 10 (03) ◽  
pp. 395-401
Author(s):  
Mohammad K. Hammood ◽  
Maryam Hamed
Keyword(s):  
Flow Injection ◽  
Mefenamic Acid ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Basic Medium ◽  
Minimum Concentration ◽  
Pharmaceutical Samples ◽  
Fluorescence Measurements ◽  
532 Nm

Mefenamic acid belongs to non-steroidal anti-inflammatory drugs that are used widely for the treatment of analgesia. Our aim from this study is to establish a new assay for the quantitative determination of mefenamic acid (MFA) in the pharmaceutical sample by two sensitive and rapid flow injection-fluorometric methods. A homemade fluorometer was used in fluorescence measurements, which using solid-state laser diode 405 and 532 nm as a source, combined with a continuous flow injection technique. The first method depends on the effect of MFA on calcein blue (CLB) fluorescence at 405 nm. Another method is a study of rhodamine-6G (Rh-6G) fluorescence after adding MFA, and recording at 532 nm. Optimum parameters as fluorescent dye concentration, basic medium, flow rate, sample volume, purge time, and delay coil have been investigated. The dynamic range of MFA was 0.2 to 2 mmol.L-1; 0.5 to 2.3 mmol.L-1 with linearity percentage (% r2) 98.92 and 99.83%, for Rh-6G and CLB, respectively. Limit of detection at a minimum concentration in calibration curve 189.34 and 199.89 ng/sample, for Rh-6G and CLB, respectively. The comparison of developed methods with the classical method (UV-vis spectrophotometry) was achieved. The proposed methods were successfully applied for the determination of MFA in the pharmaceutical samples and can be used as an alternative method.

Decreased photosynthetic efficiency in plant species exposed to multiple airborne pollutants along the Russian-Norwegian border

2000 ◽  
Vol 78 (8) ◽  
pp. 1021-1033 ◽  
Author(s):  
Ann Marie Odasz-Albrigtsen ◽  
Hans Tømmervik ◽  
Patrick Murphy
Keyword(s):  
Chlorophyll Fluorescence ◽  
Plant Species ◽  
Photosynthetic Efficiency ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Plant Cover ◽  
Mixed Forest ◽  
Airborne Pollutants ◽  
Fluorescence Measurements ◽  
Study Sites

Photosynthetic efficiency was estimated by chlorophyll fluorescence measurements (Fv/Fm) in 11 plant species growing along a steep gradient of airborne pollution along the Russian-Norwegian border (70°N, 30°E). Photosynthetic efficiency was positively correlated with environmental variables including annual temperature and a maritime gradient and was negatively correlated with the airborne concentrations of Cu, Ni, and SO2 from the Cu-Ni smelters. Photosynthetic efficiency in six plant species from the mixed forest, but not pine (Pinus sylvestris L.), and three species from the birch forest was inversely correlated with SO2 and the concentrations of Ni and Cu in lichens. Measurement of fluorescence in these species was a sensitive indicator of pollutant impact. Plant cover at the 16 study sites and the photosynthetic efficiency of five target species correlated with normalized difference vegetation index (NDVI) values. This study demonstrated that it is possible to detect relations among field-measured ecophysiological responses in plants, levels of airborne pollutants, and satellite remote-sensed data.Key words: chlorophyll fluorescence, smelters, sulfur dioxide, nickel, copper, normalized difference vegetation index (NDVI).

scholarly journals Response of growth, quality parameters and photosynthetic apparatus of endive plant to different culture media

2016 ◽  
Vol 28 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Katarzyna Kowalczyk ◽  
Janina Gajc-Wolska ◽  
Monika Marcinkowska ◽  
Magdalena D. Cetner ◽  
Hazem M. Kalaji
Keyword(s):  
Nutrient Solution ◽  
Photosynthetic Efficiency ◽  
Culture Medium ◽  
Photosynthetic Apparatus ◽  
Quality Parameters ◽  
Ion Concentration ◽  
Soluble Solids ◽  
Growth Media ◽  
Dry Matter Content ◽  
Fluorescence Measurements

AbstractEndive (Cichorium endiviaL.) is a leaf vegetable with high vitamin and nutritional values. Therefore, an increase of its cultivation in Poland and other European countries has been observed in recent years. The aim of this research was to study the effect of different growth media on the quality and photosynthetic efficiency of different endive cultivars. The experiment was conducted in controlled greenhouse conditions. Endive was grown in three independent NFT cultivation systems: a standard culture medium (control, A1), a culture medium concentrated three-fold (A2) and a medium concentrated five-fold (A3). Four cultivars were used: ‘Kethel’, ‘Barundi’, ‘Galanti’ and ‘Perceval’. The plants were examined for the number and weight of fully-grown leaves and the weight of roots, dry matter content and chemical quality attributes of endive such as ascorbic acid (AA), total soluble solids (TSS), chlorophyll and proline. In addition, several physiological traits such as modulated chlorophyllafluorescence were measured.Both three-fold and five-fold increases of ion concentration in the nutrient solution induced stress in the endive plants. Our results showed that the photosynthetic efficiency of the tested endive plants was affected by the cultivar factor and only the highest (five-fold) ion concentration in the nutrient solution. Growth under a medium of three-fold ion concentration did not affect the photosynthetic efficiency, despite observed changes in the growth and quality parameters of the endive plants. This study suggests that the type of fluorescence measurements used in this experiment (modulated) cannot be recommended as a sufficient bioindicator during endive production.

scholarly journals Crystal Structure of the YchF Protein Reveals Binding Sites for GTP and Nucleic Acid

2003 ◽  
Vol 185 (14) ◽  
pp. 4031-4037 ◽  
Author(s):  
Alexey Teplyakov ◽  
Galina Obmolova ◽  
Seung Y. Chu ◽  
John Toedt ◽  
Edward Eisenstein ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Nucleic Acid ◽  
Binding Site ◽  
Coiled Coil ◽  
Genomic Analysis ◽  
Protein Fluorescence ◽  
Terminal Domain ◽  
Fluorescence Measurements ◽  
Α Helix

ABSTRACT The bacterial protein encoded by the gene ychF is 1 of 11 universally conserved GTPases and the only one whose function is unknown. The crystal structure determination of YchF was sought to help with the functional assignment of the protein. The YchF protein from Haemophilus influenzae was cloned and expressed, and the crystal structure was determined at 2.4 Å resolution. The polypeptide chain is folded into three domains. The N-terminal domain has a mononucleotide binding fold typical for the P-loop NTPases. An 80-residue domain next to it has a pronounced α-helical coiled coil. The C-terminal domain features a six-stranded half-barrel that curves around an α-helix. The crablike three-domain structure of YchF suggests the binding site for a double-stranded nucleic acid in the cleft between the domains. The structure of the putative GTP-binding site is consistent with the postulated guanine specificity of the protein. Fluorescence measurements have demonstrated the ability of YchF to bind a double-stranded nucleic acid and GTP. Taken together with other experimental data and genomic analysis, these results suggest that YchF may be part of a nucleoprotein complex and may function as a GTP-dependent translation factor.

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