Sample records for relative variable fluorescence
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PHYTOPLANKTON NUTRIENT STATUS AND VARIABLE FLUORESCENCE MEASUREMENTS IN A GULF COAST ESTUARY
Changes in variable fluorescence parameters such as the maximum quantum yield of fluorescence (a.k.a. photosynthetic efficiency and Fv/Fm) have been related to nutrient status in single-species cultures. To test if changes in Fv/Fm of mixed natural assemblages were related to nut...
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Belkhodja, R.; Morales, F.; Abadia, A.; Gomez-Aparisi, J.; Abadia, J.
1994-01-01
The application of chlorophyll fluorescence measurements to screening barley (Hordeum vulgare L.) genotypes for salinity tolerance has been investigated. Excised barley leaves were cut under water and incubated with the cut end immersed in water or in a 100-mM NaCl solution, either in the dark or in high light. Changes in rapid fluorescence kinetics occurred in excised barley leaves exposed to the saline solution only when the incubation was carried out in the presence of high light. Fluorescence changes consisted of decreases in the variable to maximum fluorescence ratio and in increases in the relative proportion of variable fluorescence leading to point I in the Kautsky fluorescence induction curve. These relative increases in fluorescence at point I appeared to arise from a delayed plastoquinone reoxidation in the dark, since they disappeared after short, far-red illumination, which is known to excite photosystem I preferentially. We show that a significant correlation existed between some fluorescence parameters, measured after a combined salt and high-light treatment, and other independent measurements of salinity tolerance. These results suggest that chlorophyll fluorescence, and especially the relative fluorescence at point I in the Kautsky fluorescence induction curve, could be used for the screening of barley genotypes for salinity tolerance. PMID:12232117
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Temporal variability in chlorophyll fluorescence of back-reef corals in Ofu, American Samoa
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.
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Schelly, Robert C.; Smith, W. Leo; Davis, Matthew P.; Tchernov, Dan; Pieribone, Vincent A.
2014-01-01
The discovery of fluorescent proteins has revolutionized experimental biology. Whereas the majority of fluorescent proteins have been identified from cnidarians, recently several fluorescent proteins have been isolated across the animal tree of life. Here we show that biofluorescence is not only phylogenetically widespread, but is also phenotypically variable across both cartilaginous and bony fishes, highlighting its evolutionary history and the possibility for discovery of numerous novel fluorescent proteins. Fish biofluorescence is especially common and morphologically variable in cryptically patterned coral-reef lineages. We identified 16 orders, 50 families, 105 genera, and more than 180 species of biofluorescent fishes. We have also reconstructed our current understanding of the phylogenetic distribution of biofluorescence for ray-finned fishes. The presence of yellow long-pass intraocular filters in many biofluorescent fish lineages and the substantive color vision capabilities of coral-reef fishes suggest that they are capable of detecting fluoresced light. We present species-specific emission patterns among closely related species, indicating that biofluorescence potentially functions in intraspecific communication and evidence that fluorescence can be used for camouflage. This research provides insight into the distribution, evolution, and phenotypic variability of biofluorescence in marine lineages and examines the role this variation may play. PMID:24421880
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Sparks, John S; Schelly, Robert C; Smith, W Leo; Davis, Matthew P; Tchernov, Dan; Pieribone, Vincent A; Gruber, David F
2014-01-01
The discovery of fluorescent proteins has revolutionized experimental biology. Whereas the majority of fluorescent proteins have been identified from cnidarians, recently several fluorescent proteins have been isolated across the animal tree of life. Here we show that biofluorescence is not only phylogenetically widespread, but is also phenotypically variable across both cartilaginous and bony fishes, highlighting its evolutionary history and the possibility for discovery of numerous novel fluorescent proteins. Fish biofluorescence is especially common and morphologically variable in cryptically patterned coral-reef lineages. We identified 16 orders, 50 families, 105 genera, and more than 180 species of biofluorescent fishes. We have also reconstructed our current understanding of the phylogenetic distribution of biofluorescence for ray-finned fishes. The presence of yellow long-pass intraocular filters in many biofluorescent fish lineages and the substantive color vision capabilities of coral-reef fishes suggest that they are capable of detecting fluoresced light. We present species-specific emission patterns among closely related species, indicating that biofluorescence potentially functions in intraspecific communication and evidence that fluorescence can be used for camouflage. This research provides insight into the distribution, evolution, and phenotypic variability of biofluorescence in marine lineages and examines the role this variation may play.
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NASA Astrophysics Data System (ADS)
Zavoruev, V. V.; Domysheva, V. M.; Pestunov, D. A.; Sakirko, M. V.; Panchenko, M. V.
2018-04-01
The process of gas exchange of CO2 in the atmosphere-water system and its relation to the daily course of variable fluorescence of phytoplankton is studied on the basis of long-term (2004-2014) measurements during the open water period for Lake Baikal. It is found that the decrease in photosynthetic activity of plankton is almost synchronous to the increase in the CO2 flux from atmosphere to water. It follows from comparison of the spring and summer data with December measurements that the daily decrease in variable fluorescence of phytoplankton is caused by the internal daily rhythm of the photosynthetic activity of plankton.
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NASA Technical Reports Server (NTRS)
Stegmann, P. M.; Lewis, M. R.; Davis, C. O.; Cullen, J. J.
1992-01-01
Biological, optical, and hydrographical data were collected on the WEC88 cruise along 150 deg W and during a 6-day time-series station on the equator during February/March 1988. This area was characterized by a subsurface chlorophyll maximum (SCM), located at 50-70 m depth at the equator and descending down to 120-125 m at the north and south end of the transect. Highest primary production rates were near-surface and confined to the equatorial region and stations between 7 deg and 11 deg N. To determine the relationship between solar-stimulated fluorescence (centered at 683 nm wavelength) and primary production, a production-fluorescence model based on phytoplankton physiology and marine optics is described. Results of model calculations predict that there is a linear relation between production and fluorescence. A comparison between morning and midday measurements of the production-fluorescence relation showed that there was some difference between the two, whereas evening measurements, on the other hand, were distinctly different from the morning/midday ones. This seems to suggest that diurnal variations contribute significantly to variability in the quantum yield of photochemical processes. The ratio of the quantum yield of photosynthesis to the quantum yield of fluorescence ranged between 0.24 and 0.44 molC/Ein for all stations. The highest value for this ratio occurred at the equatorial stations, indicating that latitudinal variability could have an effect on the production-fluorescence relation.
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Larkum, A W; Wood, W F
1993-04-01
Several species of marine benthic algae, four species of phytoplankton and two species of seagrass have been subjected to ultraviolet B irradiation for varying lengths of time and the effects on respiration, photosynthesis and fluorescence rise kinetics studied. No effect on respiration was found. Photosynthesis was inhibited to a variable degree in all groups of plants after irradiation over periods of up to 1 h and variable fluorescence was also inhibited in a similar way. The most sensitive plants were phytoplankton and deep-water benthic algae. Intertidal benthic algae were the least sensitive to UV-B irradiation and this may be related to adaptation, through the accumulation of UV-B screening compounds, to high light/high UV-B levels. Inhibition of variable fluorescence (Fv) of the fluorescence rise curve was a fast and sensitive indicator of UV-B damage. Two plants studied, a brown alga and a seagrass, showed very poor recovery of Fv over a period of 32 h.
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Ospina Calvo, Brian; Parapugna, Tamara L; Lagorio, M Gabriela
2017-05-17
The main goal of the present work was to clarify physiological strategies in plants whose chloroplasts were developed under different light environments. The specific objective was to elucidate the influence of the spectral distribution of light on the chlorophyll fluorescence ratio and on photosynthetic parameters. To achieve this purpose, three species of eggplant fruit (black, purple and white striped and white) were used as a case study and their chlorophyll fluorescence was analyzed in detail. Spectra of the non-variable fluorescence in each part of the fruit were corrected for distortions by light reabsorption processes using a physical model. The main conclusion of this work was that the corrected fluorescence ratio was dependent on the contribution of each photosystem to the fluorescence and consequently on the environmental lighting conditions, becoming higher when illumination was rich in long wavelengths. Variable chlorophyll fluorescence, similar to that observed from plant leaves, was detected for the pulp of the black eggplant, for the pulp of the purple and white striped eggplant and for the intact fruit of the black eggplant. The maximum quantum efficiency of photosystem II in the light-adapted state (F' v /F' m ), the quantum efficiency of photosystem II (Φ PSII ), and the photochemical and non-photochemical quenching coefficients (qP and qNP/NPQ respectively) were determined in each case. The results could be explained very interestingly, in relation with the proportion of exciting light reaching each photosystem (I and II). The photochemical parameters obtained from variable chlorophyll fluorescence, allowed us to monitor non-destructively the physiological state of the black fruit during storage under both chilled or room-temperature conditions.
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Assaad, Aziz; Pontvianne, Steve; Pons, Marie-Noëlle
2017-05-01
To rapidly monitor the surface water quality in terms of organic pollution of an industrial river undergoing restoration, optical methods (UV-visible spectrometry and fluorescence) were applied in parallel to classical physical-chemical analyses. UV-visible spectra were analyzed using the maximum of the second derivative at 225 nm (related to nitrates), specific absorbance at 254 nm (SUVA 254 ), and the spectral slope between 275 and 295 nm (S 275-295 ) (related to the aromaticity and molecular weight of dissolved organic carbon). The synchronous fluorescence spectra (wavelength difference = 50 nm) exhibited a high variability in the composition of dissolved organic material between the upstream and downstream sections and also versus time. The principal components analysis of the entire set of synchronous fluorescence spectra helped to define three river sections with different pollution characteristics. Spectral decomposition was applied to the two most upstream sections: five fluorophores, classical in rivers impacted by domestic sewage and related to protein-like (λ ex = 280 nm) and humic-like fluorescence (M-type with λ ex ≈ 305-310 nm and C-type with λ ex ≥ 335 nm), were identified. The irregular shape of the synchronous fluorescence spectra in the most downstream section is likely due to organic pollutants of industrial origin; however, their variability and the complexity of the spectra did not allow the further elucidation of their nature.
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Duda, J.J.; Freeman, D.C.; Brown, M.L.; Graham, J.H.; Krzysik, A.J.; Emlen, J.M.; Zak, J.C.; Kovacic, D.A.
2004-01-01
We used developmental instability, water potential, and variable fluorescence to determine if populations of winged sumac (Rhus copallinum) were being negatively effected by military training disturbance. We established nine sites that represented a land-use disturbance gradient with three impact levels (low, medium, and high), the effects mostly due to mechanized infantry training maneuvers. Although mean values of developmental instability, water potential, and variable fluorescence differed significantly among sites, the patterns did not consistently differentiate sites relative to the disturbance gradient. At the population level, some measures of developmental instability and variable fluorescence were positively correlated. All nine sites consisted of habitat mosaics, with the abundance of higher quality habitat patches and canopy gaps closely related to habitat impacts. It may be that R. copallinum is selecting similar micro-environments at all sites and therefore minimizing inter-site variation in stress measures, despite large differences in overall habitat condition. Our results call for caution in developing ecological indicators using the response of physiological and morphological measures from a single plant species. ?? 2003 Elsevier Ltd. All rights reserved.
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NASA Astrophysics Data System (ADS)
First, Matthew R.; Robbins-Wamsley, Stephanie H.; Riley, Scott C.; Drake, Lisa A.
2018-03-01
Variable fluorescence fluorometry, an analytical approach that estimates the fluorescence yield of chlorophyll a (F0, a proximal measure of algal concentration) and photochemical yield (FV/FM, an indicator of the physiological status of algae) was evaluated as a means to rapidly assess photoautotrophs. Specifically, it was used to gauge the efficacy of ballast water treatment designed to reduce the transport and delivery of potentially invasive organisms. A phytoflagellate, Tetraselmis spp. (10-12 μm) and mixed communities of ambient protists were examined in both laboratory experiments and large-scale field trials simulating 5-d hold times in mock ballast tanks. In laboratory incubations, ambient organisms held in the dark exhibited declining F0 and FV/FM measurements relative to organisms held under lighted conditions. In field experiments, increases and decreases in F0 and FV/FM over the tank hold time corresponded to those of microscope counts of organisms in two of three trials. In the third trial, concentrations of organisms ≥ 10 and < 50 μm (presumably heterotrophic protists) increased while F0 and FV/FM decreased. Rapid and sensitive, variable fluorescence fluorometry is appropriate for detecting changes in organism concentrations and physiological status in samples dominated by microalgae. Changes in the heterotrophic community, which may become more prevalent in light-limited ballast tanks, would not be detected via variable fluorescence fluorometry, however.
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Prado, E A; Faivre-Rampant, P; Schneider, C; Darmency, M A
1996-10-01
Fluorescent in situ hybridization (FISH) was applied to related Populus species (2n = 19) in order to detect rDNA loci. An interspecific variability in the number of hybridization sites was revealed using as probe an homologous 25S clone from Populus deltoides. The application of image analysis methods to measure fluorescence intensity of the hybridization signals has enabled us to characterize major and minor loci in the 18S-5.8S-25S rDNA. We identified one pair of such rDNA clusters in Populus alba; two pairs, one major and one minor, in both Populus nigra and P. deltoides; and three pairs in Populus balsamifera, (two major and one minor) and Populus euroamericana (one major and two minor). FISH results are in agreement with those based on RFLP analysis. The pBG13 probe containing 5S sequence from flax detected two separate clusters corresponding to the two size classes of units that coexist within 5S rDNA of most Populus species. Key words : Populus spp., fluorescent in situ hybridization, FISH, rDNA variability, image analysis.
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NASA Astrophysics Data System (ADS)
D'Sa, E. J.; Kim, H. C.; Ha, S. Y.
2016-12-01
Colored dissolved organic matter (CDOM) spectral absorption and excitation-emission matrix (EEMs) fluorescence with parallel factor analysis (PARAFAC) were examined in the Ross Sea during a survey conducted on board the R/V Araon in the austral summer of 14/15. CDOM absorption at 355 nm ranged from 0.06 to 1.14 m-1 while spectral slope S calculated between 275-295 nm wavelength ranged from 18.83 to 33.32 µm-1 with water masses playing an important role in its variability. Spectral slope S decreased with increasing CDOM absorption indicating the strong role of photo-oxidation on CDOM abundance during the summer. PARAFAC analysis of EEM data identified two humic-like (terrestrial and marine-like) and a protein-like (tryptophan-like) component. The two humic-like components were well correlated with little variability spatially and across the water column ( 0-100 m) likely indicating more refractory material. The protein-like fluorescent component was relatively quite variable supporting the autochthonous production of this fluorescent component in the highly productive Ross Sea waters.
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Dimmable electronic ballasts by variable power density modulation technique
NASA Astrophysics Data System (ADS)
Borekci, Selim; Kesler, Selami
2014-11-01
Dimming can be accomplished commonly by switching frequency and pulse density modulation techniques and a variable inductor. In this study, a variable power density modulation (VPDM) control technique is proposed for dimming applications. A fluorescent lamp is operated in several states to meet the desired lamp power in a modulation period. The proposed technique has the same advantages of magnetic dimming topologies have. In addition, a unique and flexible control technique can be achieved. A prototype dimmable electronic ballast is built and experiments related to it have been conducted. As a result, a 36WT8 fluorescent lamp can be driven for a desired lamp power from several alternatives without modulating the switching frequency.
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Development of tolerance of egg plant (Solanum melangena L.) to field application of dimethoate.
Khillar, R; Acharya, S; Mohapatra, P K
2010-07-01
Dimethoate, at field concentration (1.419 mg g(-1) fr wt), caused inhibition of photosynthesis, transpiration and stomatal conductance of Solanum melangena L. on first treatment but subsequent treatments caused adaptation and recovery of these parameters. The variable fluorescence (F(v)), dissipation (DI(0)/RC), 2 ms relative variable fluorescence (V(j)), net rate of PS II closure (M(0)), and maximum trapping rate of active PS II (TR(0)/RC) increased initially but reduced to the control value with repetition of treatment. However, fluorescence yield (TR(0)/Abs), electron transport probability (ET(0)/TR(0)) and activity of RC (ET(0)/RC) increased with each treatment. With each subsequent treatment there was enhancement of activities of esterases and decrease of insecticide content of leaves.
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Torres, Rocio; Diz, Virginia E; Lagorio, M Gabriela
2018-04-18
Effects of gold nanoparticles (average diameter: 10-14 nm) on leaves and chloroplasts have been studied. Gold nanoparticles (AuNPs) quenched significantly chlorophyll fluorescence when introduced both in intact leaves and isolated chloroplasts. Additionally, the fluorescence spectra corrected for light re-absorption processes showed a net decrease in the fluorescence ratio calculated as the quotient between the maximum fluorescence at 680 and 735 nm. This fact gave evidence for a reduction in the fluorescence emission of the PSII relative to that of the PSI. Strikingly, the photosynthetic parameters derived from the analysis of the slow phase of Kautsky's kinetics, the rate of oxygen evolution and the rate of photo-reduction of 2,6-dichlorophenolindophenol were increased in the presence of AuNPs indicating an apparent greater photosynthetic capacity. The observed results were consistent with an electron transfer process from the excited PSII, which was thermodynamically possible, and which competed with both the electron transport process that initiated photosynthesis and the deactivation of the excited PSII by fluorescence emission. Additionally, it is here explained, in terms of a completely rational kinetic scheme and their corresponding algebraic expressions, why the photosynthetic parameters and the variable and non-variable fluorescence of chlorophyll are modified in a photosynthetic tissue containing gold nanoparticles.
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Lee, Noah; Laine, Andrew F; Smith, R Theodore
2007-01-01
Fundus auto-fluorescence (FAF) images with hypo-fluorescence indicate geographic atrophy (GA) of the retinal pigment epithelium (RPE) in age-related macular degeneration (AMD). Manual quantification of GA is time consuming and prone to inter- and intra-observer variability. Automatic quantification is important for determining disease progression and facilitating clinical diagnosis of AMD. In this paper we describe a hybrid segmentation method for GA quantification by identifying hypo-fluorescent GA regions from other interfering retinal vessel structures. First, we employ background illumination correction exploiting a non-linear adaptive smoothing operator. Then, we use the level set framework to perform segmentation of hypo-fluorescent areas. Finally, we present an energy function combining morphological scale-space analysis with a geometric model-based approach to perform segmentation refinement of false positive hypo- fluorescent areas due to interfering retinal structures. The clinically apparent areas of hypo-fluorescence were drawn by an expert grader and compared on a pixel by pixel basis to our segmentation results. The mean sensitivity and specificity of the ROC analysis were 0.89 and 0.98%.
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A fluorimetric study of the thorium-morin system
Milkey, Robert G.; Fletcher, Mary H.
1956-01-01
Thorium reacts with morin to yield a yellow complex that fluoresces when irradiated with ultraviolet light. The effect on the fluorescence of such variable as concentration of acid, alcohol, thorium, morin, and complex; time, temperature, and wavelength of exciting light are studied to determine experimental conditions yielding maximum fluorescence. The effects of Zr4+, Al3+, Fe3+, Ca2+, and La3+ are discussed. The fundamental relationships between light absorption and fluorescence are expressed in a general equation which applied to a three-component system when the fluorescence is measured in a transmission-type fluorimeter. This general equation is used to obtain an expression for the fluorescence of the thorium-morin system. Equations, derived from experimental data, related both the fraction of thorium reacted to form complex and the fraction of unquenched fluorescence to the concentration of uncombined morin. These functions, when combined with the general equation, give an expression which relates the total net fluorescence to the amount of uncombined morin in the solution. This last equation can be used to determine the one region for the concentration of uncombined morin that gives maximum sensitivity for the system. Calculated standard curves are in excellent agreement with experimental curves.
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NASA Astrophysics Data System (ADS)
Guadagno, C. R.; Beverly, D.; Pleban, J. R.; Speckman, H. N.; Ewers, B. E.; Weinig, C.
2017-12-01
Aridity is one of the most pronounced environmental limits to plant survival, and understanding how plants respond to drought and recovery is crucial for predicting impacts on managed and natural ecosystems. Changes in soil moisture conditions induce a suite of physiological responses from the cell to ecosystem scale, complicating the assessment of drought effects. Characterizing early indicators of water scarcity across species can inform biophysical models with improved understanding of plant hydraulics. While indexes exist for drought monitoring across scales, many are unable to identify imminent vegetative drought. We explore a method of early diagnosis using leaf-level and kinetic imaging measures of variable chlorophyll a fluorescence. This is a fast and reliable tool capturing leaf physiological changes in advance of changes in NDVI or passive solar induced fluorescence. Both image and leaf level Pulse Amplitude Method (PAM) measurements illustrate the utility of variable chlorophyll a fluorescence for monitoring vegetative drought. Variable fluorescence was monitored across populations of crops, desert shrubs, montane conifers and riparian deciduous trees under variable water regimes. We found a strong correlation (R = 0.85) between the maximum efficiency of photosystem II measured using variable fluorescence (Fv'Fm') and leaf level electrolyte leakage, a proximal cause of drought stress induced by cellular damage in leaves. This association was confirmed in two gymnosperm species (Picea engelmannii and Pinus contorta) and for diverse varieties of the crop species Brassica rapa. The use of chlorophyll a fluorescence per image also allowed for early detection of drought in aspen (Populus tremuloides). These results provide evidence that variable chlorophyll fluorescence decreases between 25% and 70% in mild and severely droughted twigs with respect to ones collected from trees in wet soil conditions. While current systems for monitoring variable fluorescence are limited in scale, chlorophyll fluorescence comprises an indicator of drought stress across multiple spatial scales, from leaf to ecosystem level.
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NASA Astrophysics Data System (ADS)
Joiner, J.; Yoshida, Y.; Guanter, L.; Zhang, Y.; Vasilkov, A. P.; Schaefer, K. M.; Huemmrich, K. F.; Middleton, E.; Koehler, P.; Jung, M.; Tucker, C. J.; Lyapustin, A.; Wang, Y.; Frankenberg, C.; Berry, J. A.; Koster, R. D.; Reichle, R. H.; Lee, J. E.; Kawa, S. R.; Collatz, G. J.; Walker, G. K.; Van der Tol, C.
2014-12-01
Over the past several years, there have been several breakthroughs in our ability to detect the very small fluorescence emitted by chlorophyll in vegetation globally from space. There are now multiple instruments in space capable of measuring this signal at varying temporal and spatial resolutions. We will review the state-of-the-art with respect to these relatively new satellite measurements and ongoing studies that examine the relationships with photosynthesis. Now that we have a data record spanning more than seven years, we can examine variations due to seasonal carbon uptake, interannual variability, land-use changes, and water and temperature stress. In addition, we examine how clouds and satellite viewing geometry impact the signal. We compare and contrast these variations with those from popular vegetation indices, such as the Normalized Difference Vegetation Index (NDVI), related to the potential photosynthesis as well as with measurements from flux tower gas exchange measurements and other model-based estimates of Global Primary Productivity (GPP). Vegetation fluorescence can be simulated in global vegetation models as well as with 1D canopy radiative transport models. We will describe how the satellite fluorescence data are being used to evaluate and potentially improve these models.
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Nian, Linge; Hu, Yue; Fu, Caihong; Song, Chen; Wang, Jie; Xiao, Jianxi
2018-01-01
The development of novel assays to detect collagen fragments is of utmost importance for diagnostic, prognostic and therapeutic decisions in various collagen-related diseases, and one essential question is to discover probe peptides that can specifically recognize target collagen sequences. Herein we have developed the fluorescence self-quenching assay as a convenient tool to screen the capability of a series of fluorescent probe peptides of variable lengths to bind with target collagen peptides. We have revealed that the targeting ability of probe peptides is length-dependent, and have discovered a relatively short probe peptide FAM-G(POG) 8 capable to identify the target peptide. We have further demonstrated that fluorescence self-quenching assay together with this short probe peptide can be applied to specifically detect the desired collagen fragment in complex biological media. Fluorescence self-quenching assay provides a powerful new tool to discover effective peptides for the recognition of collagen biomarkers, and it may have great potential to identify probe peptides for various protein biomarkers involved in pathological conditions. Copyright © 2017 Elsevier B.V. All rights reserved.
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Dunstan, R A; Simpson, M B
1985-12-01
We have used fluorescence flow cytometry to analyse cell-to-cell variability in the density of platelet ABH, Ii, Lewis, P, P1A1, Bak,a and HLA class I antigens. Human IgG and IgM antibodies were used in a two-stage assay with goat FITC-conjugated antihuman IgG (H&L) antibody as the label, followed by single cell analysis of 10 000 platelets per sample using a 256-channel fluorescence flow cytometer (Becton-Dickinson FACS Analyser). Computer analysis of fluorescence intensity histograms for mean and peak channel and coefficient of variation shows that the degree of heterogeneity in platelet antigen density varies with each particular blood group. The broad fluorescence distribution curves with oligosaccharide antigens (CVs: A = 53, B = 40, I = 44, Lea = 40, P = 40) indicate that these antigens possess a greater variability in the number of sites per cell compared to the more homogeneous distribution of P1,A1 BaK,a and HLA (CVs: P1A1 = 24, HLA = 30). These findings may partly account for the mechanism by which transfusion of ABO-incompatible platelets results in a biphasic survival curve, with a period of early rapid removal of those platelets with a high density of antigen sites, followed by a relatively normal survival curve for those platelets that possess only a few or no antigen sites. In contrast, P1A1 and HLA sites are less variable in number from one platelet to another in a given donor, and immune-mediated removal would be more likely to approximate a single exponential curve.
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Rascher, U; Alonso, L; Burkart, A; Cilia, C; Cogliati, S; Colombo, R; Damm, A; Drusch, M; Guanter, L; Hanus, J; Hyvärinen, T; Julitta, T; Jussila, J; Kataja, K; Kokkalis, P; Kraft, S; Kraska, T; Matveeva, M; Moreno, J; Muller, O; Panigada, C; Pikl, M; Pinto, F; Prey, L; Pude, R; Rossini, M; Schickling, A; Schurr, U; Schüttemeyer, D; Verrelst, J; Zemek, F
2015-12-01
Variations in photosynthesis still cause substantial uncertainties in predicting photosynthetic CO2 uptake rates and monitoring plant stress. Changes in actual photosynthesis that are not related to greenness of vegetation are difficult to measure by reflectance based optical remote sensing techniques. Several activities are underway to evaluate the sun-induced fluorescence signal on the ground and on a coarse spatial scale using space-borne imaging spectrometers. Intermediate-scale observations using airborne-based imaging spectroscopy, which are critical to bridge the existing gap between small-scale field studies and global observations, are still insufficient. Here we present the first validated maps of sun-induced fluorescence in that critical, intermediate spatial resolution, employing the novel airborne imaging spectrometer HyPlant. HyPlant has an unprecedented spectral resolution, which allows for the first time quantifying sun-induced fluorescence fluxes in physical units according to the Fraunhofer Line Depth Principle that exploits solar and atmospheric absorption bands. Maps of sun-induced fluorescence show a large spatial variability between different vegetation types, which complement classical remote sensing approaches. Different crop types largely differ in emitting fluorescence that additionally changes within the seasonal cycle and thus may be related to the seasonal activation and deactivation of the photosynthetic machinery. We argue that sun-induced fluorescence emission is related to two processes: (i) the total absorbed radiation by photosynthetically active chlorophyll; and (ii) the functional status of actual photosynthesis and vegetation stress. © 2015 John Wiley & Sons Ltd.
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NASA Astrophysics Data System (ADS)
Corcel, Mathias; Devaux, Marie-Françoise; Guillon, Fabienne; Barron, Cécile
2017-06-01
Powders produced from plant materials are heterogeneous in relation to native plant heterogeneity, and during grinding, dissociation often occurred at the tissue scale. The tissue composition of powdery samples could be modified through dry fractionation diagrams and impact their end-uses properties. If tissue identification is often made on native plant structure, this characterization is not straightforward in destructured samples such powders. Taking advantage of the autofluorescence properties of cell wall components, multispectral image acquisition is envisioned to identify the tissular origin of particles. Images were acquired on maize stem sections and ground tissues isolated from the same stem by hand dissection. The variability in fluorescence intensity profiles was analysed using principal component analysis. The correspondence between fluorescence profiles and the different tissues observed in maize sections was assessed based on histology or known compositional heterogeneity. Similar variability was encountered in fluorescence profiles extracted from powder leading to the potential ability to predict tissular origin based on this autofluorescence multispectral signal.
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NASA Astrophysics Data System (ADS)
Bhatta, H.; Goldys, E. M.; Ma, J.
2006-02-01
We characterised populations of wild type baking and brewing yeast cells using intrinsic fluorescence and fluorescence lifetime microscopy, in order to obtain quantitative identifiers of different strains. The cell autofluorescence was excited at 405 nm and observed within 440-540 nm range where strong cell to cell variability was observed. The images were analyzed using customised public domain software, which provided information on cell size, intensity and texture-related features. In light of significant diversity of the data, statistical methods were utilized to assess the validity of the proposed quantitative identifiers for strain differentiation. The Kolmogorov-Smirnov test was applied to confirm that empirical distribution functions for size, intensity and entropy for different strains were statistically different. These characteristics were followed with culture age of 24, 48 and 72 h, (the latter corresponding to a stationary growth phase) and size, and to some extent entropy, were found to be independent of age. The fluorescence intensity presented a distinctive evolution with age, different for each of the examined strains. The lifetime analysis revealed a short decay time component of 1.4 ns and a second, longer one with the average value of 3.5 ns and a broad distribution. High variability of lifetime values within cells was observed however a lifetime texture feature in the studied strains was statistically different.
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NASA Astrophysics Data System (ADS)
Hoge, Frank E.; Wright, C. Wayne; Kana, Todd M.; Swift, Robert N.; Yungel, James K.
1998-07-01
We report spatial variability of oceanic phycoerythrin spectral types detected by means of a blue spectral shift in airborne laser-induced fluorescence emission. The blue shift of the phycoerythrobilin fluorescence is known from laboratory studies to be induced by phycourobilin chromophore substitution at phycoerythrobilin chromophore sites in some strains of phycoerythrin-containing marine cyanobacteria. The airborne 532-nm laser-induced phycoerythrin fluorescence of the upper oceanic volume showed distinct segregation of cyanobacterial chromophore types in a flight transect from coastal water to the Sargasso Sea in the western North Atlantic. High phycourobilin levels were restricted to the oceanic (oligotrophic) end of the flight transect, in agreement with historical ship findings. These remotely observed phycoerythrin spectral fluorescence shifts have the potential to permit rapid, wide-area studies of the spatial variability of spectrally distinct cyanobacteria, especially across interfacial regions of coastal and oceanic water masses. Airborne laser-induced phytoplankton spectral fluorescence observations also further the development of satellite algorithms for passive detection of phytoplankton pigments. Optical modifications to the NASA Airborne Oceanographic Lidar are briefly described that permitted observation of the fluorescence spectral shifts.
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Singh, Shatrughan; D'Sa, Eurico J; Swenson, Erick M
2010-07-15
Chromophoric dissolved organic matter (CDOM) variability in Barataria Basin, Louisiana, USA,was examined by excitation emission matrix (EEM) fluorescence combined with parallel factor analysis (PARAFAC). CDOM optical properties of absorption and fluorescence at 355nm along an axial transect (36 stations) during March, April, and May 2008 showed an increasing trend from the marine end member to the upper basin with mean CDOM absorption of 11.06 + or - 5.01, 10.05 + or - 4.23, 11.67 + or - 6.03 (m(-)(1)) and fluorescence 0.80 + or - 0.37, 0.78 + or - 0.39, 0.75 + or - 0.51 (RU), respectively. PARAFAC analysis identified two terrestrial humic-like (component 1 and 2), one non-humic like (component 3), and one soil derived humic acid like (component 4) components. The spatial variation of the components showed an increasing trend from station 1 (near the mouth of basin) to station 36 (end member of bay; upper basin). Deviations from this increasing trend were observed at a bayou channel with very high chlorophyll-a concentrations especially for component 3 in May 2008 that suggested autochthonous production of CDOM. The variability of components with salinity indicated conservative mixing along the middle part of the transect. Component 1 and 4 were found to be relatively constant, while components 2 and 3 revealed an inverse relationship for the sampling period. Total organic carbon showed increasing trend for each of the components. An increase in humification and a decrease in fluorescence indices along the transect indicated an increase in terrestrial derived organic matter and reduced microbial activity from lower to upper basin. The use of these indices along with PARAFAC results improved dissolved organic matter characterization in the Barataria Basin. Copyright 2010 Elsevier B.V. All rights reserved.
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A fluorimetric study of the thorium-morin system
Milkey, R.G.; Fletcher, M.H.
1957-01-01
Thorium reacts with morin to yield a yellow complex that fluoresces when irradiated with ultraviolet light. The effect on the fluorescence of such variables as concentration of acid, alcohol, thorium, morin, and complex; time, temperature and wave length of exciting light are studied to determine experimental conditions yielding maximum fluorescence. The effects of Zr+4, Al+3, Fe+3, Ca+2 and La+3 are discussed. The fundamental relationships between light absorption and fluorescence are expressed in a general equation that applies to a three-component system when the fluorescence is measured in a transmission-type fluorimeter. This general equation is used to obtain an expression for the fluorescence of the thoriummorin system. Equations, derived from experimental data, relate both the fraction of thorium reacted to form complex and the fraction of unquenched fluorescence to the concentration of uncombined morin. These functions, when combined with the general equation, give an expression whichrelates the total net fluorescence to the amount of uncombined morin in the solution. This last equation can be used to determine the one region for the concentration of uncombined morin that gives maximum sensitivity for the system. Calculated standard curves are in good agreement with experimental curves.
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The influence of indoxyl sulfate and ammonium on the autofluorescence of human urine.
Perinchery, Sandeep Menon; Kuzhiumparambil, Unnikrishnan; Vemulpad, Subramanyam; Goldys, Ewa M
2010-01-15
Despite biological variability the spectral characteristics of undiluted human urine show relatively low autofluorescence at short UV (250-300nm) excitation. However with dilution the fluorescence intensity remarkably increases. This paper examines the mechanisms behind this effect, by using excitation-emission matrices. Corrections for the inner filter effect were made for improved understanding of the spectral patterns. We focused on three major fluorophores (tryptophan, indoxyl sulfate and 5-hydroxyindole-3-acetate) that are excited at these wavelengths, and whose content in urine is strongly linked with various health conditions. Their fluorescence was studied both individually and in combinations. We also examined the effect of ammonium on the fluorescence of these major fluorophores individually and in combinations. Through these studies we have identified the leading effects that reduce the UV fluorescence, namely higher concentration of indoxyl sulfate producing the inner filter effect and concentration quenching and quenching of fluorophores by ammonium. This result will assist in broader utilisation of UV fluorescence in medical diagnostics.
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Drakaki, E; Makropoulou, M; Serafetinides, A A
2008-07-01
In dermatology, the in vivo spectral fluorescence measurements of human skin can serve as a valuable supplement to standard non-invasive techniques for diagnosing various skin diseases. However, quantitative analysis of the fluorescence spectra is complicated by the fact that skin is a complex multi-layered and inhomogeneous organ, with varied optical properties and biophysical characteristics. In this work, we recorded, in vitro, the laser-induced fluorescence emission signals of healthy porcine skin, one of the animals, which is considered as one of the most common models for investigations related to medical diagnostics of human cutaneous tissues. Differences were observed in the form and intensity of the fluorescence signal of the porcine skin, which can be attributed to the different concentrations of the native fluorophores and the variable physical and biological conditions of the skin tissue. As the light transport in the tissue target is directly influencing the absorption and the fluorescence emission signals, we performed Monte Carlo simulation of the light distribution in a five-layer model of human skin tissue, with a pulsed ultraviolet laser beam.
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NASA Technical Reports Server (NTRS)
Hallidy, William H. (Inventor); Chin, Robert C. (Inventor)
1999-01-01
The present invention is a system for chemometric analysis for the extraction of the individual component fluorescence spectra and fluorescence lifetimes from a target mixture. The present invention combines a processor with an apparatus for generating an excitation signal to transmit at a target mixture and an apparatus for detecting the emitted signal from the target mixture. The present invention extracts the individual fluorescence spectrum and fluorescence lifetime measurements from the frequency and wavelength data acquired from the emitted signal. The present invention uses an iterative solution that first requires the initialization of several decision variables and the initial approximation determinations of intermediate matrices. The iterative solution compares the decision variables for convergence to see if further approximation determinations are necessary. If the solution converges, the present invention then determines the reduced best fit error for the analysis of the individual fluorescence lifetime and the fluorescence spectrum before extracting the individual fluorescence lifetime and fluorescence spectrum from the emitted signal of the target mixture.
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Carmo, A.M.; Stankiewicz, B.A.; Mastalerz, Maria; Pratt, L.M.
1997-01-01
The molecular and elemental composition of immature kerogens isolated from Upper Cretaceous marine carbonates from Sergipe Basin, Brazil were investigated using combined pyrolysis-gas chromatography/mass spectrometry and organic petrographic techniques. The kerogens are predominantly composed of reddish-fluorescing amorphous organic matter (AOM) and variable amounts of yellow-fluorescing alginite and liptodetrinite. The abundance of organic sulfur in the kerogens inferred from the ratio 2-ethyl-5-methylthiophene/(1,2-dimethylbenzene + dec-1-ene) in the pyrolyzates is variable and may be related to changes in the type of primary organic input and/or to variations in rates of bacterial sulfate reduction. A concomitant increase in S/C and O/C ratios determined in situ using the electron microprobe is observed in AOM and alginites and may be related to a progressive oxidation of the organic matter during sulfurization. The S/C ratio of the AOM is systematically higher than the S C ratio of the alginites. Combined with a thiophene distribution characteristic of pyrolyzates of Type II organic matter, the higher S/C of AOM in Sergipe kerogens suggests that sulfurization and incorporation of low-molecular weight lipids derived from normal marine organic matter into the kerogen structure predominated over direct sulfurization of highly aliphatic algal biomacromolecules.The molecular and elemental composition of immature kerogens isolated from Upper Cretaceous marine carbonates from Sergipe Basin, Brazil were investigated using combined pyrolysis-gas chromatography/mass spectrometry and organic petrographic techniques. The kerogens are predominantly composed of reddish-fluorescing amorphous organic matter (AOM) and variable amounts of yellow-fluorescing alginite and liptodetrinite. The abundance of organic sulfur in the kerogens inferred from the ratio 2-ethyl-5-methylthiophene/(1,2-dimethylbenzene+dec-1-ene) in the pyrolyzates is variable and may be related to changes in the type of primary organic input and/or to variations in rates of bacterial sulfate reduction. A concomitant increase in S/C and O/C ratios determined in situ using the electron microprobe is observed in AOM and alginites and may be related to a progressive oxidation of the organic matter during sulfurization. The S/C ratio of the AOM is systematically higher than the S/C ratio of the alginites. Combined with a thiophene distribution characteristic of pyrolyzates of Type II organic matter, the higher S/C of AOM in Sergipe kerogens suggests that sulfurization and incorporation of low-molecular weight lipids derived from normal marine organic matter into the kerogen structure predominated over direct sulfurization of highly aliphatic algal biomacromolecules.
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NASA Astrophysics Data System (ADS)
Blauw, Anouk N.; Benincà, Elisa; Laane, Remi W. P. M.; Greenwood, Naomi; Huisman, Jef
2018-02-01
Phytoplankton concentrations display strong temporal variability at different time scales. Recent advances in automated moorings enable detailed investigation of this variability. In this study, we analyzed phytoplankton fluctuations at four automated mooring stations in the North Sea, which measured phytoplankton abundance (chlorophyll) and several environmental variables at a temporal resolution of 12-30 min for two to nine years. The stations differed in tidal range, water depth and freshwater influence. This allowed comparison of the predictability and environmental drivers of phytoplankton variability across different time scales and geographical regions. We analyzed the time series using wavelet analysis, cross correlations and generalized additive models to quantify the response of chlorophyll fluorescence to various environmental variables (tidal and meteorological variables, salinity, suspended particulate matter, nitrate and sea surface temperature). Hour-to-hour and day-to-day fluctuations in chlorophyll fluorescence were substantial, and mainly driven by sinking and vertical mixing of phytoplankton cells, horizontal transport of different water masses, and non-photochemical quenching of the fluorescence signal. At the macro-tidal stations, these short-term phytoplankton fluctuations were strongly driven by the tides. Along the Dutch coast, variation in salinity associated with the freshwater influence of the river Rhine played an important role, while in the central North Sea variation in weather conditions was a major determinant of phytoplankton variability. At time scales of weeks to months, solar irradiance, nutrient conditions and thermal stratification were the dominant drivers of changes in chlorophyll concentrations. These results show that the dominant drivers of phytoplankton fluctuations differ across marine environments and time scales. Moreover, our findings show that phytoplankton variability on hourly to daily time scales should not be dismissed as environmental noise, but is related to vertical and horizontal particle transport driven by winds and tides. Quantification of these transport processes contributes to an improved predictability of marine phytoplankton concentrations.
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Frank, Simon; Goeppert, Nadine; Goldscheider, Nico
2018-02-15
Karst springs, especially in alpine regions, are important for drinking water supply but also vulnerable to contamination, especially after rainfall events. This high variability of water quality requires rapid quantification of contamination parameters. Here, we used a fluorescence-based multi-parameter approach to characterize the dynamics of organic carbon, faecal bacteria, and particles at three alpine karst springs. We used excitation emission matrices (EEMs) to identify fluorescent dissolved organic material (FDOM). At the first system, peak A fluorescence and total organic carbon (TOC) were strongly correlated (Spearman's r s of 0.949), indicating that a large part of the organic matter is related to humic-like substances. Protein-like fluorescence and cultivation-based determination of coliform bacteria also had a significant correlation with r s =0.734, indicating that protein-like fluorescence is directly related to faecal pollution. At the second system, which has two spring outlets, the absolute values of all measured water-quality parameters were lower; there was a significant correlation between TOC and humic-like fluorescence (r s =0.588-0.689) but coliform bacteria and protein-like fluorescence at these two springs were not correlated. Additionally, there was a strong correlation (r s =0.571-0.647) between small particle fractions (1.0 and 2.0μm), a secondary turbidity peak and bacteria. At one of these springs, discharge was constant despite the reaction of all other parameters to the rainfall event. Our results demonstrated that i) all three springs showed fast and marked responses of all investigated water-quality parameters after rain events; ii) a constant discharge does not necessarily mean constant water quality; iii) at high contamination levels, protein-like fluorescence is a good indicator of bacterial contamination, while at low contamination levels no correlation between protein-like fluorescence and bacterial values was detected; and iv) a combination of fluorescence measurements and particle-size analysis is a promising approach for a rapid assessment of organic contamination, especially relative to time-consuming conventional bacterial determination methods. Copyright © 2017 Elsevier B.V. All rights reserved.
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NASA Technical Reports Server (NTRS)
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.
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NASA Astrophysics Data System (ADS)
Simmons, L. J.; Fobbe, D. J.; Berges, J. A.
2016-02-01
Understanding the dynamics of phytoplankton communities has traditionally focused on differences in growth and related processes among taxa. It is now appreciated that differences in mortality could be equally important in contributing to these dynamics. Studying mortality in communities is difficult, especially on relevant time scales, which could be as short as hours to days. Flow cytometry can potentially provide solutions, because it can allow discrimination of different taxa, and when combined with staining, distinguish live and dead cells. We applied flow cytometry and staining to phytoplankton communities in a model system: a small, well-studied, urban pond in southeastern Wisconsin. Using flow cytometry, it was possible to resolve up to six dominant taxa (most <37 µm) and track them through an annual cycle. However, the axes traditionally used, forward scatter (FSC, related to cell size) and red fluorescence (FL3, related to chlorophyll a content) offered poor discrimination. Addition of orange fluorescence (FL2, traditionally related to phycobilipigments) and side scatter (SSC, related to cell surface characteristics) improved separation of taxa, but reproducibility (i.e. the specific position of the taxa on axes) was also more sensitive to environmental variation in the case of the fluorescence parameters. Dead cells could be distinguished by green fluorescence (FL1, using SYTOX Green©), but the stain also affected other fluorescence channels, requiring compensation. Correlations of numbers of dead cells with environmental factors (e.g. temperature, nutrient concentrations, irradiance) were generally poor, suggesting the greater importance of biotic versus abiotic variables in community mortality dynamics. Ongoing work is focusing on the effects of viral pathogens, grazing and allelopathic interactions using experimental manipulations and individual-based modeling.
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Samson, G; Popovic, R
1988-12-01
The phytotoxicity of heavy metals and pesticides was studied by using the fluorescence induction from the alga Dunaliella tertiolecta. The complementary area calculated from the variable fluorescence induction was used as a direct parameter to estimate phytotoxicity. The value of this parameter was affected when algae were treated with different concentrations of mercury, copper, atrazine, DCMU, Dutox, and Soilgard. The toxic effect of these pollutants was estimated by monitoring the decrease in the complementary area, which reflects photosystem II photochemistry. Further, the authors have demonstrated the advantage of using the complementary area as a parameter of phytotoxicity over using variable fluorescence yield. The complementary area of algal fluorescence can be used as a simple and sensitive parameter in the estimation of the phytotoxicity of polluted water.
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Diode laser-based thermometry using two-line atomic fluorescence of indium and gallium
NASA Astrophysics Data System (ADS)
Borggren, Jesper; Weng, Wubin; Hosseinnia, Ali; Bengtsson, Per-Erik; Aldén, Marcus; Li, Zhongshan
2017-12-01
A robust and relatively compact calibration-free thermometric technique using diode lasers two-line atomic fluorescence (TLAF) for reactive flows at atmospheric pressures is investigated. TLAF temperature measurements were conducted using indium and, for the first time, gallium atoms as temperature markers. The temperature was measured in a multi-jet burner running methane/air flames providing variable temperatures ranging from 1600 to 2000 K. Indium and gallium were found to provide a similar accuracy of 2.7% and precision of 1% over the measured temperature range. The reliability of the TLAF thermometry was further tested by performing simultaneous rotational CARS measurements in the same experiments.
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Shan, Huimei; Liu, Chongxuan; Wang, Zheming; ...
2015-01-01
A new method was developed for rapid and direct measurement of polybrominated diphenyl ethers (PBDEs) in aqueous samples using fluorescence spectroscopy. The fluorescence spectra of tri- to deca-BDE (BDE 28, 47, 99, 153, 190, and 209) commonly found in environment were measured at variable emission and excitation wavelengths. The results revealed that the PBDEs have distinct fluorescence spectral profiles and peak positions that can be exploited to identify these species and determine their concentrations in aqueous solutions. The detection limits as determined in deionized water spiked with PBDEs are 1.71-5.82 ng/L for BDE 28, BDE 47, BDE 190, and BDEmore » 209 and 45.55–69.95 ng/L for BDE 99 and BDE 153. The effects of environmental variables including pH, humic substance, and groundwater chemical composition on PBDEs measurements were also investigated. These environmental variables affected fluorescence intensity, but their effect can be corrected through linear additivity and separation of spectral signal contribution. Compared with conventional GC-based analytical methods, the fluorescence spectroscopy method is more efficient as it only uses a small amount of samples (2-4 mL), avoids lengthy complicated concentration and extraction steps, and has a low detection limit of a few ng/L.« less
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Yan, Caixia; Liu, Huihui; Sheng, Yanru; Huang, Xian; Nie, Minghua; Huang, Qi; Baalousha, Mohammed
2018-10-01
Characterization of natural colloids is the key to understand pollutant fate and transport in the environment. The present study investigates the relationship between size and fluorescence properties of colloidal organic matter (COM) from five tributaries of Poyang Lake. Colloids were size-fractionated using cross-flow ultrafiltration and their fluorescence properties were measured by three-dimensional excitation-emission matrix fluorescence spectroscopy (3D-EEM). Parallel factor analysis (PARAFAC) and/or Self-organizing map (SOM) were applied to assess fluorescence properties as proxy indicators for the different size of colloids. PARAFAC analysis identified four fluorescence components including three humic-like components (C1-C3) and a protein-like component (C4). These four fluorescence components, and in particular the protein-like component, are primarily present in <1 kDa phase. For the colloidal fractions (1-10 kDa, 10-100 kDa, and 100 kDa-0.7 μm), the majority of fluorophores are associated with the smallest size fraction. SOM analysis demonstrated that relatively high fluorescence intensity and aromaticity occur primarily in <1 kDa phase, followed by 1-10 kDa colloids. Coupling PARAFAC and SOM facilitate the visualization and interpretation of the relationship between colloidal size and fluorescence properties with fewer input variables, shorter running time, higher reliability, and nondestructive results. Fluorescence indices analysis reveals that the smallest colloidal fraction (1-10 kDa) was dominated by higher humified and less autochthonous COM. Copyright © 2018 Elsevier B.V. All rights reserved.
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NASA Astrophysics Data System (ADS)
Saito Nogueira, Marcelo; Kurachi, Cristina
2016-03-01
Photoaging is the skin premature aging due to exposure to ultraviolet light, which damage the collagen, elastin and can induce alterations on the skin cells DNA, and, then, it may evolve to precancerous lesions, which are widely investigated by fluorescence spectroscopy and lifetime. The fluorescence spectra and fluorescence lifetime analysis has been presented as a technique of great potential for biological tissue characterization at optical diagnostics. The main targeted fluorophores are NADH (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide), which have free and bound states, each one with different average lifetimes. The average lifetimes for free and bound NADH and FAD change according to tissue metabolic alterations and may contribute to a non-invasive clinical investigation of injuries such as skin lesions. These lesions and the possible areas where they may develop can be interrogated using fluorescence lifetime spectroscopy taking into account the variability of skin phototypes and the changes related to melanin, collagen and elastin, endogenous fluorophores which have emissions that spectrally overlap to the NADH and FAD emission. The objective of this study is to assess the variation on fluorescence lifetimes of normal skin at sun exposed and non-exposed areas and associate this variation to the photoaging process.
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Jedmowski, Christoph; Brüggemann, Wolfgang
2015-10-01
We quantified the influence of heat stress (HS) on PSII by imaging of parameters of the fast chlorophyll fluorescence (CF) induction (OJIP) kinetic of 20 genotypes of wild barley (Hordeum spontaneum) covering a broad geographical spectrum. We developed a standardised screening procedure, allowing a repetitive fluorescence measurement of leaf segments. The impact of HS was quantified by calculating a Heat Resistance Index (HRI), derived from the decrease of the Performance Index (PI) caused by HS treatment and following recovery. For the genotype showing the lowest HRI, reduced maximum quantum yield (φP0) and increased relative variable fluorescence of the O-J phase (K-Peak) were detected after HS, whereas the basal fluorescence (F0) remained stable. An additional feature was a lowered fraction of active (QA-reducing) reaction centres (RCs). The disturbances disappeared after one day of recovery. Spatial heterogeneities of fluorescence parameters were detected, as the negative effect of HS was stronger in the leaf areas close to the leaf tip. The results of this study prove that chlorophyll fluorescence imaging (CFI) is suitable for the detection of HS symptoms and that imaging of JIP-Test parameters should be considered in future screening and phenotyping studies aiming for the characterisation of plant genotypes. Copyright © 2015 Elsevier B.V. All rights reserved.
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Carbone, Teresa; Gilio, Michele; Padula, Maria Carmela; Tramontano, Giuseppina; D'Angelo, Salvatore; Pafundi, Vito
2018-05-01
Indirect Immunofluorescence (IIF) is widely considered the Gold Standard for Antinuclear Antibody (ANA) screening. However, the high inter-reader variability remains the major disadvantage associated with ANA testing and the main reason for the increasing demand of the computer-aided immunofluorescence microscope. Previous studies proposed the quantification of the fluorescence intensity as an alternative for the classical end-point titer evaluation. However, the different distribution of bright/dark light linked to the nature of the self-antigen and its location in the cells result in different mean fluorescence intensities. The aim of the present study was to correlate Fluorescence Index (F.I.) with end-point titers for each well-defined ANA pattern. Routine serum samples were screened for ANA testing on HEp-2000 cells using Immuno Concepts Image Navigator System, and positive samples were serially diluted to assign the end-point titer. A comparison between F.I. and end-point titers related to 10 different staining patterns was made. According to our analysis, good technical performance of F.I. (97% sensitivity and 94% specificity) was found. A significant correlation between quantitative reading of F.I. and end-point titer groups was observed using Spearman's test and regression analysis. A conversion scale of F.I. in end-point titers for each recognized ANA-pattern was obtained. The Image Navigator offers the opportunity to improve worldwide harmonization of ANA test results. In particular, digital F.I. allows quantifying ANA titers by using just one sample dilution. It could represent a valuable support for the routine laboratory and an effective tool to reduce inter- and intra-laboratory variability. Copyright © 2018. Published by Elsevier B.V.
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Clarke, Richard W; Monnier, Nilah; Li, Haitao; Zhou, Dejian; Browne, Helena; Klenerman, David
2007-08-15
We present a single virion method to determine absolute distributions of copy number in the protein composition of viruses and apply it to herpes simplex virus type 1. Using two-color coincidence fluorescence spectroscopy, we determine the virion-to-virion variability in copy numbers of fluorescently labeled tegument and envelope proteins relative to a capsid protein by analyzing fluorescence intensity ratios for ensembles of individual dual-labeled virions and fitting the resulting histogram of ratios. Using EYFP-tagged capsid protein VP26 as a reference for fluorescence intensity, we are able to calculate the mean and also, for the first time to our knowledge, the variation in numbers of gD, VP16, and VP22 tegument. The measurement of the number of glycoprotein D molecules was in good agreement with independent measurements of average numbers of these glycoproteins in bulk virus preparations, validating the method. The accuracy, straightforward data processing, and high throughput of this technique make it widely applicable to the analysis of the molecular composition of large complexes in general, and it is particularly suited to providing insights into virus structure, assembly, and infectivity.
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Application of fluorescence spectroscopy for on-line bioprocess monitoring and control
NASA Astrophysics Data System (ADS)
Boehl, Daniela; Solle, D.; Toussaint, Hans J.; Menge, M.; Renemann, G.; Lindemann, Carsten; Hitzmann, Bernd; Scheper, Thomas-Helmut
2001-02-01
12 Modern bioprocess control requires fast data acquisition and in-time evaluation of bioprocess variables. On-line fluorescence spectroscopy for data acquisition and the use of chemometric methods accomplish these requirements. The presented investigations were performed with fluorescence spectrometers with wide ranges of excitation and emission wavelength. By detection of several biogenic fluorophors (amino acids, coenzymes and vitamins) a large amount of information about the state of the bioprocess are obtained. For the evaluation of the process variables partial least squares regression is used. This technique was applied to several bioprocesses: the production of ergotamine by Claviceps purpurea, the production of t-PA (tissue plasminogen activator) by animal cells and brewing processes. The main point of monitoring the brewing processes was to determine the process variables cell count and extract concentration.
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Phytoplankton natural fluorescence variability in the Sargasso Sea
NASA Astrophysics Data System (ADS)
Westberry, T. K.; Siegel, D. A.
2003-03-01
Phytoplankton fluorescence has been used historically as a means of assessing phytoplankton biomass, rates of primary production (PP) and physiological status in laboratory, in situ, and satellite based investigations. Assumptions about the quantum yield of phytoplankton fluorescence, φf, are often overlooked and can become problematic when fluorescence based methods are applied. A time series of φf observations from the northwestern Sargasso Sea is presented with the goal of understanding the controls on fluorescence and its applicability for assessing upper ocean biological processes. Accurate estimates of φf require accounting for Raman scattering and the conversion of planar to scalar irradiance. Variability in φf occurs on both seasonal and episodic time scales. Seasonal variations show maxima in the surface layer during summer months while lower, more uniform values are found throughout the winter when deep mixing occurs. Large episodic variations in φf are observed throughout the record which dwarf seasonal changes. Predictions of depth-dependent and depth-integrated PP rates using φf and natural fluorescence fluxes are only marginally successful ( r2˜50%), although comparable with results from global bio-optical models for the Sargasso Sea. Improvements in PP predictions are hindered by weak statistical relationships with other parameters. φf is largely decoupled from the quantum yield of carbon assimilation, φc, indicating that an inverse relationship between fluorescence and photosynthesis does not exist. Consequently, variability in the quantum yield of thermal de-excitation, φh, is found to be of similar magnitude as φf on the timescales observed. These observations show that assumptions about photochemical energy flow through the phytoplankton community must be made carefully and that the fluorescence-photosynthesis relationship is not straightforward.
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Drivers and variability of the Chl fluorescence emission spectrum from the leaf through the canopy
NASA Astrophysics Data System (ADS)
Magney, T. S.; Frankenberg, C.; Grossman, K.; Koehler, P.; North, G.; Porcar-Castell, A.; Stutz, J.; Fisher, J.
2017-12-01
Recent advances in the retrieval of solar induced chlorophyll fluorescence (SIF) from remote sensing platforms provide a significant step towards mapping instantaneous plant photosynthesis across space and time. However, our current understanding of the variability and controls on the shape of the chlorophyll fluorescence (ChlF) spectrum is limited. To address these uncertainties, we have developed instrumentation to make highly resolved spectral measurements of SIF from both leaf and canopy scales. At the leaf scale, we simultaneously collected active (PAM) and passive (675-850 nm) fluorescence with photosynthesis across a range of species and conditions; and at the canopy scale, diurnal and seasonal Fraunhofer-based SIF retrievals across the red and far-red spectrum are made at four different flux tower sites (Costa Rica, Iowa (2), and Colorado). From both of these scales we are able to determine (1) the variability in steady-state spectra across species and individuals; and (2) the environmental, functional, and structural controls on SIF. Here we report on the sensitivity of SIF spectra from a singular value decomposition analysis; and present on the mechanisms - pigment concentration, species, non-photochemical and photochemical quenching, and environmental conditions - controlling SIF variability. Further, we will discuss how an improved understanding of leaf-level variability can inform canopy level SIF, and ultimately how such information may enable proper interpretation of satellite retrievals.
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NASA Astrophysics Data System (ADS)
Leh, Barbara; Siebert, Rainer; Hamzeh, Hussein; Menard, Laurent; Duval, Marie-Alix; Charon, Yves; Abi Haidar, Darine
2012-10-01
Growing interest in optical instruments for biomedical applications has increased the use of optically calibrated phantoms. Often associated with tissue modeling, phantoms allow the characterization of optical devices for clinical purposes. Fluorescent gel phantoms have been developed, mimicking optical properties of healthy and tumorous brain tissues. Specific geometries of dedicated molds offer multiple-layer phantoms with variable thicknesses and monolayer phantoms with cylindrical inclusions at various depths and diameters. Organic chromophores are added to allow fluorescence spectroscopy. These phantoms are designed to be used with 405 nm as the excitation wavelength. This wavelength is then adapted to excite large endogenous molecules. The benefits of these phantoms in understanding fluorescence tissue analysis are then demonstrated. In particular, detectability aspects as a function of geometrical and optical parameters are presented and discussed.
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NASA Technical Reports Server (NTRS)
Middleton, Elizabeth M.; Rascher, Uwe; Corp, Lawrence A.; Huemmrich, K. Fred; Cook, Bruce D.; Noormets, Asko; Schickling, Anke; Pinto, Francisco; Alonso, Luis; Damm, Alexander;
2017-01-01
The first European Space Agency (ESA) and NASA collaboration in an airborne campaign to support ESA's FLuorescence EXplorer (FLEX) mission was conducted in North Carolina, USA during September-October 2013 (FLEX-US 2013) at the Parker Tract Loblolly Pine (LP) Plantation (Plymouth, NC, USA). This campaign combined two unique airborne instrument packages to obtain simultaneous observations of solar-induced fluorescence (SIF), LiDAR-based canopy structural information, visible through shortwave infrared (VSWIR) reflectance spectra, and surface temperature, to advance vegetation studies of carbon cycle dynamics and ecosystem health. We obtained statistically significant results for fluorescence, canopy temperature, and tower fluxes from data collected at four times of day over two consecutive autumn days across an age class chronosequence. Both the red fluorescence (F685) and far-red fluorescence (F740) radiances had highest values at mid-day, but their fluorescence yields exhibited different diurnal responses across LP age classes. The diurnal trends for F685 varied with forest canopy temperature difference (canopy minus air), having a stronger daily amplitude change for young vs. old canopies. The Photochemical Reflectance Index (PRI) was positively correlated with this temperature variable over the diurnal cycle. Tower measurements from mature loblolly stand showed the red/far-red fluorescence ratio was linearly related to canopy light use efficiency (LUE) over the diurnal cycle, but performed even better for the combined morning/afternoon (without midday) observations. This study demonstrates the importance of diurnal observations for interpretation of fluorescence dynamics, the need for red fluorescence to understand canopy physiological processes, and the benefits of combining fluorescence, reflectance, and structure information to clarify canopy function versus structure characteristics for a coniferous forest.
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Study of the Many Fluorescent Lines and the Absorption Variability in GX 301-2 with XMM-Newton
NASA Technical Reports Server (NTRS)
Fuerst, F.; Suchy, S.; Kreykenbohm, I.; Barragan, L.; Wilms, J.; Pottschmidt, K.; Caballero, I.; Kretschmar, P.; Ferrigno, C.; Rothschild, R. E.
2011-01-01
We present an in-depth study of the High Mass X-ray Binary (HMXB) GX 301-2 during its pre-periastron flare using data from the XMM-Newton satellite. The energy spectrum shows a power law continuum absorbed by a large equivalent hydrogen column on the order of 10(exp 24)/ sq cm and a prominent Fe K-alpha fluorescent emission line. Besides the Fe K-alpha line, evidence for Fe K-Beta, Ni K-alpha, Ni K-Beta, S K-alpha, Ar K-alpha, Ca K-alpha, and Cr K-alpha fluorescent lines is found. The observed line strengths are consistent with fluorescence in a cold absorber. This is the first time that Cr K-alpha is seen in emission in the X-ray spectrum of a HMXB. In addition to the modulation by the strong pulse period of approx 685 sec the source is highly variable and shows different states of activity. We perform time-resolved as well as pulse-to-pulse resolved spectroscopy to investigate differences between these states of activity. We find that fluorescent line fluxes are strongly variable and generally follow the overall flux. The N-H value is variable by a factor of 2, but not correlated to continuum normalization. We find an interval of low flux in the light curve in which the pulsations cease almost completely, without any indication of an increasing absorption column. We investigate this dip in detail and argue that it is most likely that during the dip the accretion ceased and the afterglow of the fluorescent iron accounted for the main portion of the X-ray flux. A similar dip was found earlier in RXTE data, and we compare our findings to these results.
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NASA Astrophysics Data System (ADS)
Kimura, Hiroaki; Momiyama, Masashi; Tomita, Katsuro; Tsuchiya, Hiroyuki; Hoffman, Robert M.
2010-11-01
We demonstrate the development of a long-working-distance fluorescence microscope with high-numerical-aperture objectives for variable-magnification imaging in live mice from macro- to subcellular. To observe cytoplasmic and nuclear dynamics of cancer cells in the living mouse, 143B human osteosarcoma cells are labeled with green fluorescent protein in the nucleus and red fluorescent protein in the cytoplasm. These dual-color cells are injected by a vascular route in an abdominal skin flap in nude mice. The mice are then imaged with the Olympus MVX10 macroview fluorescence microscope. With the MVX10, the nuclear and cytoplasmic behavior of cancer cells trafficking in blood vessels of live mice is observed. We also image lung metastases in live mice from the macro- to the subcellular level by opening the chest wall and imaging the exposed lung in live mice. Injected splenocytes, expressing cyan fluorescent protein, could also be imaged on the lung of live mice. We demonstrate that the MVX10 microscope offers the possibility of full-range in vivo fluorescence imaging from macro- to subcellular and should enable widespread use of powerful imaging technologies enabled by genetic reporters and other fluorophores.
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Moise, Nicolae; Moya, Ismaël
2004-06-28
The relationship between the fluorescence lifetime (tau) and yield (Phi) obtained in phase and modulation fluorometry at 54 MHz during the chlorophyll fluorescence induction in dark-adapted leaves under low actinic light has been investigated. Three typical phases have been identified: (i) linear during the OI photochemical rise, (ii) convex curvature during the subsequent IP thermal rise, and (iii) linear during the PS slow decay. A similar relationship has been obtained in the fluorescence induction for the fluorescence yield measured at 685 nm plotted versus the fluorescence yield measured at 735 nm. A spectrally resolved analysis shows that the curvature of the tau-Phi relationship is not due to chlorophyll fluorescence reabsorption effects. Several other hypotheses are discussed and we conclude that the curvature of the tau-Phi relationship is due to a variable and transitory nonphotochemical quenching. We tentatively propose that this quenching results from a conformational change of a pigment-protein complex of Photosystem II core antenna during the IP phase and could explain both spectral and temporal transitory changes of the fluorescence. A variable blue shift of the 685 nm peak of the fluorescence spectrum during the IP phase has been observed, supporting this hypothesis.
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Ozbay, Baris N.; Losacco, Justin T.; Cormack, Robert; Weir, Richard; Bright, Victor M.; Gopinath, Juliet T.; Restrepo, Diego; Gibson, Emily A.
2015-01-01
We report a miniature, lightweight fiber-coupled confocal fluorescence microscope that incorporates an electrowetting variable focus lens to provide axial scanning for full three-dimensional (3D) imaging. Lateral scanning is accomplished by coupling our device to a laser-scanning confocal microscope through a coherent imaging fiber-bundle. The optical components of the device are combined in a custom 3D-printed adapter with an assembled weight of <2 g that can be mounted onto the head of a mouse. Confocal sectioning provides an axial resolution of ~12 µm and an axial scan range of ~80 µm. The lateral field-of-view is 300 µm, and the lateral resolution is 1.8 µm. We determined these parameters by imaging fixed sections of mouse neuronal tissue labeled with green fluorescent protein (GFP) and fluorescent bead samples in agarose gel. To demonstrate viability for imaging intact tissue, we resolved multiple optical sections of ex vivo mouse olfactory nerve fibers expressing yellow fluorescent protein (YFP). PMID:26030555
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In vivo wide-field multispectral dosimeter for use in ALA-PpIX based photodynamic therapy of skin
NASA Astrophysics Data System (ADS)
LaRochelle, Ethan P. M.; Davis, Scott C.; de Souza, Ana Luiza Ribeiro; Pogue, Brian W.
2017-02-01
Photodynamic therapy (PDT) for Actinic Kertoses (AK) using aminoluvelinic acid (ALA) is an FDA-approved treatment, which is generally effective, yet response rates vary. The origin of the variability is not well characterized, but may be related to inter-patient variability in the production of protoporphyrin IX (PpIX). While fiber-based point probe systems provide a method for measuring PpIX production, these measurements have demonstrated large spatial and inter-operator variability. Thus, in an effort to improve patient-specific dosimetry and treatment it is important to develop a robust system that accounts for spatial variability and reduces the chance of operator errors. To address this need, a wide-field multispectral imaging system was developed that is capable of quantifying maps of PpIX in both liquid phantoms and in vivo experiments, focusing on high sensitivity light signals. The system uses both red and blue excitation to elicit a fluorescent response at varying skin depths. A ten-position filter wheel with bandpass filters ranging from 635nm to 710nm are used to capture images along the emission band. A linear least-square spectral fitting algorithm provides the ability to decouple background autofluorescence from PpIX fluorescence, which has improved the system sensitivity by an order of magnitude, detecting nanomolar PpIX concentrations in liquid phantoms in the presence of 2% whole blood and 2% intralipid.
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Murray, John W; Thosani, Amar J; Wang, Pijun; Wolkoff, Allan W
2011-07-01
Sodium taurocholate-cotransporting polypeptide (ntcp) is considered to be a major determinant of bile acid uptake into hepatocytes. However, the regulation of ntcp and the degree that it participates in the accumulation of specific substrates are not well understood. We utilized fluorescent bile acid derivatives and direct quantitation of fluorescent microscopy images to examine the regulation of ntcp and its role in the cell-to-cell variability of fluorescent bile acid accumulation. Primary-cultured rat hepatocytes rapidly accumulated the fluorescent bile acids, chenodeoxycholylglycylamidofluorescein (CDCGamF), 7-β- nitrobenzoxadiazole 3-α hydroxy 5-β cholan-24-oic acid (NBD-CA), and cholyl-glycylamido-fluorescein (CGamF). However, in stably transfected HeLa cells, ntcp preferred CDCGamF, whereas the organic anion transporter, organic anion transporting polypeptide 1 (oatp1a1), preferred NBD-CA, and neither ntcp nor oatp1a1 showed strong accumulation of CGamF by these methods. Ntcp-mediated transport of CDCGamF was inhibited by taurocholate, cyclosporin, actin depolymerization, and an inhibitor of atypical PKC-ζ. The latter two agents altered the cellular distribution of ntcp as visualized in ntcp-green fluorescent protein-transfected cells. Although fluorescent bile acid accumulation was reproducible by the imaging assays, individual cells showed variable accumulation that was not attributable to changes in membrane permeability or cell viability. In HeLa cells, this was accounted for by variable levels of ntcp, whereas, in hepatocytes, ntcp expression was uniform, and low accumulation was seen in a large portion of cells despite the presence of ntcp. These studies indicate that single-cell imaging can provide insight into previously unrecognized details of anion transport in the complex environment of polarized hepatocytes.
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Thosani, Amar J.; Wang, Pijun; Wolkoff, Allan W.
2011-01-01
Sodium taurocholate-cotransporting polypeptide (ntcp) is considered to be a major determinant of bile acid uptake into hepatocytes. However, the regulation of ntcp and the degree that it participates in the accumulation of specific substrates are not well understood. We utilized fluorescent bile acid derivatives and direct quantitation of fluorescent microscopy images to examine the regulation of ntcp and its role in the cell-to-cell variability of fluorescent bile acid accumulation. Primary-cultured rat hepatocytes rapidly accumulated the fluorescent bile acids, chenodeoxycholylglycylamidofluorescein (CDCGamF), 7-β- nitrobenzoxadiazole 3-α hydroxy 5-β cholan-24-oic acid (NBD-CA), and cholyl-glycylamido-fluorescein (CGamF). However, in stably transfected HeLa cells, ntcp preferred CDCGamF, whereas the organic anion transporter, organic anion transporting polypeptide 1 (oatp1a1), preferred NBD-CA, and neither ntcp nor oatp1a1 showed strong accumulation of CGamF by these methods. Ntcp-mediated transport of CDCGamF was inhibited by taurocholate, cyclosporin, actin depolymerization, and an inhibitor of atypical PKC-ζ. The latter two agents altered the cellular distribution of ntcp as visualized in ntcp-green fluorescent protein-transfected cells. Although fluorescent bile acid accumulation was reproducible by the imaging assays, individual cells showed variable accumulation that was not attributable to changes in membrane permeability or cell viability. In HeLa cells, this was accounted for by variable levels of ntcp, whereas, in hepatocytes, ntcp expression was uniform, and low accumulation was seen in a large portion of cells despite the presence of ntcp. These studies indicate that single-cell imaging can provide insight into previously unrecognized details of anion transport in the complex environment of polarized hepatocytes. PMID:21474652
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NASA Astrophysics Data System (ADS)
O'Hara, Julia A.; Samkoe, Kimberley S.; Chen, Alina; Isabelle, Martin; Hoopes, P. J.; Hasan, Tayyaba; Pogue, Brian W.
2012-02-01
Photodynamic therapy (PDT) that uses the second generation photosensitizer, verteporfin (VP), is a developing therapy for pancreatic cancer. The optimal timing of light delivery related to VP uptake and distribution in pancreatic tumors will be important information to obtain to improve treatment for this intractable disease. In this work we examined uptake and distribution of VP in two orthotopic pancreatic tumors with different histological structure. ASPC-1 (fast-growing) and Panc-1 (slower growing) tumors were implanted in SCID mice and studied when tumors were approximately 100mm3. In a pilot study, these tumors had been shown to differ in uptake of VP using lightinduced fluorescence spectroscopy (LIFS) in vivo and fluorescence imaging ex vivo and that work is extended here. In vivo fluorescence mean readings of tumor and liver increased rapidly up to 15 minutes after photosensitizer injection for both tumor types, and then continued to increase up to 60 minutes post injection to a higher level in ASPC-1 than in Panc-1. There was variability among animals with the same tumor type, in both liver and tumor uptake and no selectivity of tumor over liver. In this work we further examined VP uptake at multiple time points in relation to microvascular density and perfusion, using DiOC7 (to mark blood vessels) and VP fluorescence in the same tissue slices. Analysis of DiOC7 fluorescence indicates that AsPC-1 and Panc-1 have different vascular densities but AsPC-1 vasculature is more perfusive. Analysis of colocalized DiOC7 and VP fluorescence showed ASPC-1 with higher accumulation of VP 3 hrs after injection and more VP at a distance from blood vessels compared to Panc-1. This work shows the need for techniques to analyze photosensitizer distribution in order to optimize photodynamic therapy as an effective treatment for pancreatic tumors.
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Microheterogeneity of actin gels formed under controlled linear shear.
Cortese, J D; Frieden, C
1988-10-01
The diffusion coefficients and fluorescence polarization properties of actin subjected to a known shear have been determined both during and after polymerization, using a modification of a cone-plate Wells-Brookfield rheometer that allows monitoring of samples with an epifluorescence microscope. Fluorescence polarization and fluorescence photobleaching recovery experiments using rhodamine-labeled actin as a tracer showed that under conditions of low shear (shear rates of 0.05 s-1), a spatial heterogeneity of polymerized actin was observed with respect to fluorescence intensity and the diffusion coefficients with actin mobility becoming quite variable in different regions of the sample. In addition, complex changes in fluorescence polarization were noted after stopping the shear. Actin filaments of controlled length were obtained using plasma gelsolin (gelsolin/actin molar ratios of 1:50 to 1:300). At ratios of 1:50, neither spatial heterogeneity nor changes in polarization were observed on subjecting the polymerized actin to shear. At ratios of approximately 1:100, a decrease on the intensity of fluorescence polarization occurs on stopping the shear. Longer filaments exhibit spatial micro-heterogeneity and complex changes in fluorescence polarization. In addition, at ratios of 1:100 or 1:300, the diffusion coefficient decreases as the total applied shear increased. This behavior is interpreted as bundling of filaments aligned under shear. We also find that the F-actin translational diffusion coefficients decrease as the total applied shear increases (shear rates between 0.05 and 12.66 s-1), as expected for a cumulative process. When chicken gizzard filamin was added to gelsolin-actin filaments (at filamin/actin molar ratios of 1:300 to 1:10), a similar decrease in the diffusion coefficients was observed for unsheared samples. Spatial microheterogeneity might be related to the effects of the shear field in the alignment of filaments, and the balance between a three-dimensional network and a microheterogeneous system (containing bundles or anisotropic phases) appears related to both shear and the presence of actin-binding proteins.
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Nesterenko, T V; Tikhomirov, A A; Shikhov, V N
2012-01-01
The effect of exciting light intensity and leaves age on characteristics of slow stage of chlorophyll fluorescence induction (CFI) of radish leaves has been investigated. Light dependence of the relationship of maximum fluorescence intensity in the peak P and the stationary fluorescence level (F(P)/F(S)) and also light dependence of temporal characteristics of CFI (T0.5 - half decrease of chlorophyll fluorescence intensity during slow stage of fluorescence induction and tmin - summarized CFI characteristics derived by calculating via integral proportional to variable part of illuminated in the result of chlorophyll fluorescence energy during slow stage of CFI) have been studied. Plants were grown in controlled conditions of light culture at 100 Wt/m2 of photosynthetic active radiation (PAR). It has been shown that variability of the characteristics under study, associated with the effect of leaves age, significantly decreases at exciting light intensity equal to 40 Wt/m2 of PAR and more. The lowest effect of leaves age on the value of fluorescence characteristics for T0.5 and tmin and also for F(P)/F(S) ratio was observed at the intensity of exciting fluorescence light of 60 Wt/m2 of PAR. In the researched range of light intensities the temporal characteristics of T0.5 and tmin for uneven-aged radish leaves appeared to be by an order less responsive to the intensity changes of exciting fluorescence light as compared with F(P)/F(S) ratio.
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NASA Astrophysics Data System (ADS)
Walther, S.; Guanter, L.; Jung, M.; Frankenberg, C.; Sun, Y.; Forkel, M.; Zhang, Y.; Duveiller, G.; Cescatti, A.; Camps-Valls, G.; Köhler, P.
2016-12-01
It is much debated whether respiration or photosynthesis drive net ecosystem productivity andwhich regions contribute strongest to the observed interannual variability (IAV) of the strengthof the land sink. Several studies point to photosynthetic productivity in semi-arid regions as avery important factor influencing atmospheric CO2 variability globally (e.g. Jung et al., 2011;Poulter et al., 2014; Ahlstr ̈ om et al., 2015). Here, we aim at a comprehensive comparison ofthe strength, timing and spatial extent of anomalies of photosynthesis as they are indicated bysatellite observations of greenness, vegetation optical depth, and sun-induced chlorophyll fluo-rescence (SIF). We will compare them to the results of diagnostic, empirical and process-basedvegetation models. Except for the evergreen tropics, the spatio-temporal patterns of monthlydominant vegetation variability are generally consistently shown in semi-arid areas, albeit withdiffering magnitudes between greenness and photosynthesis globally. Relative anomalies (to themean seasonal cycle) are particularly widespread in high northern latitudes. Further researchsteps will include i) the repeated analysis at higher temporal resolution to better refine the dif-ferent time scales of reaction between light-use-efficiency and APAR and between forestedand non-forested ecosystems, ii) investigate on characteristic time scales at which the proxies(dis-)agree and why, iii) study the relative contributions of anomalies in peak and length of thegrowing season to IAV (similar to Xia et al., 2015; Zhou et al., 2016), iv) analyse the proxiesfor possibly differing hydrological sensitivities, and v) vegetation models have long been knownto have very diverse abilities to capture GPP IAV. Our preliminary results confirm this and wewill further study possible limitations and possible ways for improvement of the simulations.
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Multi-scale controls on spatial variability in river biogeochemical cycling
NASA Astrophysics Data System (ADS)
Blaen, Phillip; Kurz, Marie; Knapp, Julia; Mendoza-Lera, Clara; Lee-Cullin, Joe; Klaar, Megan; Drummond, Jennifer; Jaeger, Anna; Zarnetske, Jay; Lewandowski, Joerg; Marti, Eugenia; Ward, Adam; Fleckenstein, Jan; Datry, Thibault; Larned, Scott; Krause, Stefan
2016-04-01
Excessive nutrient concentrations are common in surface waters and groundwaters in agricultural catchments worldwide. Increasing geomorphological heterogeneity in river channels may help to attenuate nutrient pollution by facilitating water exchange fluxes with the hyporheic zone; a site of intense microbial activity where biogeochemical cycling rates can be high. However, the controls on spatial variability in biogeochemical cycling, particularly at scales relevant for river managers, are largely unknown. Here, we aimed to assess: 1) how differences in river geomorphological heterogeneity control solute transport and rates of biogeochemical cycling at sub-reach scales (102 m); and 2) the relative magnitude of these differences versus those relating to reach scale substrate variability (103 m). We used the reactive tracer resazurin (Raz), a weakly fluorescent dye that transforms to highly fluorescent resorufin (Rru) under mildly reducing conditions, as a proxy to assess rates of biogeochemical cycling in a lowland river in southern England. Solute tracer tests were conducted in two reaches with contrasting substrates: one sand-dominated and the other gravel-dominated. Each reach was divided into sub-reaches that varied in geomorphic complexity (e.g. by the presence of pool-riffle sequences or the abundance of large woody debris). Slug injections of Raz and the conservative tracer fluorescein were conducted in each reach during baseflow conditions (Q ≈ 80 L/s) and breakthrough curves monitored using in-situ fluorometers. Preliminary results indicate overall Raz:Rru transformation rates in the gravel-dominated reach were more than 50% higher than those in the sand-dominated reach. However, high sub-reach variability in Raz:Rru transformation rates and conservative solute transport parameters suggests small scale targeted management interventions to alter geomorphic heterogeneity may be effective in creating hotspots of river biogeochemical cycling and nutrient load attenuation.
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Singh, Shatrughan; Dash, Padmanava; Silwal, Saurav; Feng, Gary; Adeli, Ardeshir; Moorhead, Robert J
2017-06-01
Water quality of lakes, estuaries, and coastal areas serves as an indicator of the overall health of aquatic ecosystems as well as the health of the terrestrial ecosystem that drains to the water body. Land use and land cover plays not only a significant role in controlling the quantity of the exported dissolved organic matter (DOM) but also influences the quality of DOM via various biogeochemical and biodegradation processes. We examined the characteristics and spatial distribution of DOM in five major lakes, in an estuary, and in the coastal waters of the Mississippi, USA, and investigated the influence of the land use and land cover of their watersheds on the DOM composition. We employed absorption and fluorescence spectroscopy including excitation-emission matrix (EEM) combined with parallel factor (PARAFAC) analysis modeling techniques to determine optical properties of DOM and its characteristics in this study. We developed a site-specific PARAFAC model to evaluate DOM characteristics resulting in five diverse DOM compositions that included two terrestrial humic-like (C1 and C3), two microbial humic-like (C2 and C5), and one protein-like (C4) DOM. Our results showed elevated fluorescence levels of microbial humic-like or protein-like DOM in the lakes and coastal waters, while the estuarine waters showed relatively high fluorescence levels of terrestrial humic-like DOM. The results also showed that percent forest and wetland coverage explained 68 and 82% variability, respectively, in terrestrial humic-like DOM exports, while 87% variability in microbially derived humiclike DOM was explained by percent agricultural lands. Strong correlations between microbial humic-like DOM and fluorescence-derived DOM indices such as biological index (BIX) and fluorescence index (FI) indicated autochthonous characteristics in the lakes, while the estuary showed largely allochthonous DOM of terrestrial origin. We also observed higher concentrations of total dissolved phosphorous (TDP) and ammonium nitrogen (NH 4 -N) in coastal waters potentially due to photodegradation of refractory DOM derived from the sediment-bound organic matter in the coastal wetlands. This study highlights the relationships between the DOM compositions in the water and the land use and land cover in the watershed. The spatial variability of DOM in three different types of aquatic environments enhances the understanding of the role of land use and land cover in carbon cycling through export of organic matter to the aquatic ecosystems..
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Quantification of retinal pigment epithelial phenotypic variation using laser scanning cytometry.
Hjelmeland, L M; Fujikawa, A; Oltjen, S L; Smit-McBride, Z; Braunschweig, D
2010-06-16
Quantifying phenotypic variation at the level of protein expression (variegation) within populations of retinal pigment epithelium (RPE) cells may be important in the study of pathologies associated with this variation. The lack of quantitative methods for examining single cells, however, and the variable presence of pigment and/or lipofuscin complicate this experimental goal. We have applied the technique of laser scanning cytometry (LSC) to paraffin sections of mouse and human eyes to evaluate the utility of LSC for these measurements. Mouse eyes were perfusion fixed in 4% paraformaldehyde and embedded in paraffin. Postmortem human eyes were fixed and dissected to obtain a 9-mm punch, which was then embedded in paraffin. A laser scanning cytometer equipped with violet, argon, and helium-neon lasers and the detectors for blue, green, and long red were used to record the fluorescence of each individual cell at all three wavelengths. Raw data were recorded and processed using the WinCyte software. Individual nuclei were identified by the fluorescence of the 4',6-diamidino-2-phenylindole (DAPI) nuclear counterstain. Next, RPE cells were uniquely identified in the green channel using an anti-retinal pigment epithelium-specific protein 65 kDa (anti-RPE65) monoclonal antibody with an Alexa Fluor 488-labeled secondary antibody. Mn-superoxide dismutase (MnSOD) was quantified in the long-red channel using an anti-MnSOD antibody and an Alexa Fluor 647-labeled secondary antibody. MnSOD(+) and RPE65(+) cells exhibited peaks in the plot of fluorescence intensity versus cell number, which could be characterized by the mean fluorescence intensity (MFI), the coefficient of variation (CV), and the percentage of total RPE cells that were also labeled for MnSOD. RPE cells can be uniquely identified in human and mouse paraffin sections by immunolabeling with anti-RPE65 antibody. A second antigen, such as MnSOD, can then be probed only within this set of RPE. Results are plotted primarily with the population frequency diagram, which can be subdivided into multiple regions. The data collected for each region include the MFI, the CV, and the number of cells that are immunolabeled in that region. Background interference from pigment or autofluorescent material can be successfully overcome by elevating the concentrations of fluorescent secondary antibodies. In the human and mouse eyes, age-related changes in MFI, CV, and percent RPE cells immunolabeled for MnSOD were observed. The extent of the variability of gene expression in RPE cells at the protein level can be quantified by LSC. Relative changes in the MFI, the CV, and/or percentage of RPE cells double labeled for a second antigen quantify the changes observed. The analysis of these data also suggest whether the effects observed are related to local changes in transcription (alterations of CV) or major changes of protein expression (MFI), which are likely to be due to changes in the chromatin structure. The changes of these variables with age suggest that the observed age-related variegation is primarily due to changes in the chromatin structure in individual cells.
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Wieners, Paul Christian; Mudimu, Opayi; Bilger, Wolfgang
2018-05-30
Desiccation-induced chlorophyll fluorescence quenching seems to be an indispensable part of desiccation resistance in the surveyed 28 green microalgal species. Lichens are desiccation tolerant meta-organisms. In the desiccated state photosynthesis is inhibited rendering the photobionts potentially sensitive to photoinhibition. As a photoprotective mechanism, strong non-radiative dissipation of absorbed light leading to quenching of chlorophyll fluorescence has been proposed. Desiccation-induced quenching affects not only variable fluorescence, but also the so-called basal fluorescence, F 0 . This phenomenon is well-known for intact lichens and some free living aero-terrestrial algae, but it was often absent in isolated lichen algae. Therefore, a thorough screening for the appearance of desiccation-induced quenching was undertaken with 13 different aero-terrestrial microalgal species and lichen photobionts. They were compared with 15 aquatic green microalgal species, among them also three marine species. We asked the following questions: Do isolated lichen algae show desiccation-induced quenching? Are aero-terrestrial algae different in this respect to aquatic algae and is the potential for desiccation-induced quenching coupled to desiccation tolerance? How variable is desiccation-induced quenching among species? Most of the aero-terrestrial algae, including all lichen photobionts, showed desiccation-induced quenching, although highly variable in extent, whereas most of the aquatic algae did not. All algae displaying quenching were also desiccation tolerant, whereas all algae unable to perform desiccation-induced quenching were desiccation intolerant. Desiccation-induced fluorescence quenching seems to be an indispensable part of desiccation resistance in the investigated species.
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NASA Astrophysics Data System (ADS)
Shan, Jiajia; Wang, Xue; Zhou, Hao; Han, Shuqing; Riza, Dimas Firmanda Al; Kondo, Naoshi
2018-04-01
Synchronous fluorescence spectra, combined with multivariate analysis were used to predict flavonoids content in green tea rapidly and nondestructively. This paper presented a new and efficient spectral intervals selection method called clustering based partial least square (CL-PLS), which selected informative wavelengths by combining clustering concept and partial least square (PLS) methods to improve models’ performance by synchronous fluorescence spectra. The fluorescence spectra of tea samples were obtained and k-means and kohonen-self organizing map clustering algorithms were carried out to cluster full spectra into several clusters, and sub-PLS regression model was developed on each cluster. Finally, CL-PLS models consisting of gradually selected clusters were built. Correlation coefficient (R) was used to evaluate the effect on prediction performance of PLS models. In addition, variable influence on projection partial least square (VIP-PLS), selectivity ratio partial least square (SR-PLS), interval partial least square (iPLS) models and full spectra PLS model were investigated and the results were compared. The results showed that CL-PLS presented the best result for flavonoids prediction using synchronous fluorescence spectra.
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Shan, Jiajia; Wang, Xue; Zhou, Hao; Han, Shuqing; Riza, Dimas Firmanda Al; Kondo, Naoshi
2018-03-13
Synchronous fluorescence spectra, combined with multivariate analysis were used to predict flavonoids content in green tea rapidly and nondestructively. This paper presented a new and efficient spectral intervals selection method called clustering based partial least square (CL-PLS), which selected informative wavelengths by combining clustering concept and partial least square (PLS) methods to improve models' performance by synchronous fluorescence spectra. The fluorescence spectra of tea samples were obtained and k-means and kohonen-self organizing map clustering algorithms were carried out to cluster full spectra into several clusters, and sub-PLS regression model was developed on each cluster. Finally, CL-PLS models consisting of gradually selected clusters were built. Correlation coefficient (R) was used to evaluate the effect on prediction performance of PLS models. In addition, variable influence on projection partial least square (VIP-PLS), selectivity ratio partial least square (SR-PLS), interval partial least square (iPLS) models and full spectra PLS model were investigated and the results were compared. The results showed that CL-PLS presented the best result for flavonoids prediction using synchronous fluorescence spectra.
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Electron-Beam Diagnostic Methods for Hypersonic Flow Diagnostics
NASA Technical Reports Server (NTRS)
1994-01-01
The purpose of this work was the evaluation of the use of electron-bean fluorescence for flow measurements during hypersonic flight. Both analytical and numerical models were developed in this investigation to evaluate quantitatively flow field imaging concepts based upon the electron beam fluorescence technique for use in flight research and wind tunnel applications. Specific models were developed for: (1) fluorescence excitation/emission for nitrogen, (2) rotational fluorescence spectrum for nitrogen, (3) single and multiple scattering of electrons in a variable density medium, (4) spatial and spectral distribution of fluorescence, (5) measurement of rotational temperature and density, (6) optical filter design for fluorescence imaging, and (7) temperature accuracy and signal acquisition time requirements. Application of these models to a typical hypersonic wind tunnel flow is presented. In particular, the capability of simulating the fluorescence resulting from electron impact ionization in a variable density nitrogen or air flow provides the capability to evaluate the design of imaging instruments for flow field mapping. The result of this analysis is a recommendation that quantitative measurements of hypersonic flow fields using electron-bean fluorescence is a tractable method with electron beam energies of 100 keV. With lower electron energies, electron scattering increases with significant beam divergence which makes quantitative imaging difficult. The potential application of the analytical and numerical models developed in this work is in the design of a flow field imaging instrument for use in hypersonic wind tunnels or onboard a flight research vehicle.
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Schlodder, Eberhard; Cetin, Marianne; Byrdin, Martin; Terekhova, Irina V; Karapetyan, Navassard V
2005-01-07
The 5 K absorption spectrum of Photosystem I (PS I) trimers from Arthrospira platensis (old name: Spirulina platensis) exhibits long-wavelength antenna (exciton) states absorbing at 707 nm (called C707) and at 740 nm (called C740). The lowest energy state (C740) fluoresces around 760 nm (F760) at low temperature. The analysis of the spectral properties (peak position and line width) of the lowest energy transition (C740) as a function of temperature within the linear electron-phonon approximation indicates a large optical reorganization energy of approximately 110 cm(-1) and a broad inhomogeneous site distribution characterized by a line width of approximately 115 cm(-1). Linear dichroism (LD) measurements indicate that the transition dipole moment of the red-most state is virtually parallel to the membrane plane. The relative fluorescence yield at 760 nm of PS I with P700 oxidized increases only slightly when the temperature is lowered to 77 K, whereas in the presence of reduced P700 the fluorescence yield increases nearly 40-fold at 77 K as compared to that at room temperature (RT). A fluorescence induction effect could not be resolved at RT. At 77 K the fluorescence yield of PS I trimers frozen in the dark in the presence of sodium ascorbate decreases during illumination by about a factor of 5 due to the irreversible formation of (P700+)F(A/B-) in about 60% of the centers and the reversible accumulation of the longer-lived state (P700+)FX-. The quenching efficiency of different functionally relevant intermediate states of the photochemistry in PS I has been studied. The redox state of the acceptors beyond A(0) does not affect F760. Direct kinetic evidence is presented that the fluorescence at 760 nm is strongly quenched not only by P700+ but also by 3P700. Similar kinetics were observed for flash-induced absorbance changes attributed to the decay of 3P700 or P700+, respectively, and flash-induced fluorescence changes at 760 nm measured under identical conditions. A nonlinear relationship between the variable fluorescence around 760 nm and the [P700red]/[P700total] ratio was derived from titration curves of the absorbance change at 826 nm and the variable fluorescence at 760 nm as a function of the redox potential imposed on the sample solution at room temperature before freezing. The result indicates that the energy exchange between the antennae of different monomers within a PS I trimer stimulates quenching of F760 by P700+.
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Chen, Jing; Ye, Wangquan; Guo, Jinjia; Luo, Zhao; Li, Ying
2016-07-13
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.
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Characterization of Fluorescent Polystyrene Microspheres for Advanced Flow Diagnostics
NASA Technical Reports Server (NTRS)
Maisto, Pietro M. F.; Lowe, K. Todd; Byun, Guibo; Simpson, Roger; Vercamp, Max; Danley, Jason E.; Koh, Brian; Tiemsin, Pacita; Danehy, Paul M.; Wohl, Christopher J.
2013-01-01
Fluorescent dye-doped polystyrene latex microspheres (PSLs) are being developed for velocimetry and scalar measurements in variable property flows. Two organic dyes, Rhodamine B (RhB) and dichlorofluorescence (DCF), are examined to assess laser-induced fluorescence (LIF) properties for flow imaging applications and single-shot temperature measurements. A major interest in the current research is the application of safe dyes, thus DCF is of particular interest, while RhB is used as a benchmark. Success is demonstrated for single-point laser Doppler velocimetry (LDV) and also imaging fluorescence, excited via a continuous wave 2 W laser beam, for exposures down to 10 ms. In contrast, when exciting with a pulsed Nd:YAG laser at 200 mJ/pulse, no fluorescence was detected, even when integrating tens of pulses. We show that this is due to saturation of the LIF signal at relatively low excitation intensities, 4-5 orders of magnitude lower than the pulsed laser intensity. A two-band LIF technique is applied in a heated jet, indicating that the technique effectively removes interfering inputs such as particle diameter variation. Temperature measurement uncertainties are estimated based upon the variance measured for the two-band LIF intensity ratio and the achievable dye temperature sensitivity, indicating that particles developed to date may provide about +/-12.5 C precision, while future improvements in dye temperature sensitivity and signal quality may enable single-shot temperature measurements with sub-degree precision.
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NASA Astrophysics Data System (ADS)
Healy, D. A.; Huffman, J. A.; O'Connor, D. J.; Pöhlker, C.; Pöschl, U.; Sodeau, J. R.
2014-08-01
Primary biological aerosol particles (PBAPs) can contribute significantly to the coarse particle burden in many environments. PBAPs can thus influence climate and precipitation systems as cloud nuclei and can spread disease to humans, animals, and plants. Measurement data and techniques for PBAPs in natural environments at high time- and size resolution are, however, sparse, and so large uncertainties remain in the role that biological particles play in the Earth system. In this study two commercial real-time fluorescence particle sensors and a Sporewatch single-stage particle impactor were operated continuously from 2 August to 2 September 2010 at a rural sampling location in Killarney National Park in southwestern Ireland. A cascade impactor was operated periodically to collect size-resolved particles during exemplary periods. Here we report the first ambient comparison of a waveband integrated bioaerosol sensor (WIBS-4) with a ultraviolet aerodynamic particle sizer (UV-APS) and also compare these real-time fluorescence techniques with results of fluorescence and optical microscopy of impacted samples. Both real-time instruments showed qualitatively similar behavior, with increased fluorescent bioparticle concentrations at night, when relative humidity was highest and temperature was lowest. The fluorescent particle number from the FL3 channel of the WIBS-4 and from the UV-APS were strongly correlated and dominated by a 3 μm mode in the particle size distribution. The WIBS FL2 channel exhibited particle modes at approx. 1 and 3 μm, and each was correlated with the concentration of fungal spores commonly observed in air samples collected at the site (ascospores, basidiospores, Ganoderma spp.). The WIBS FL1 channel exhibited variable multimodal distributions turning into a broad featureless single mode after averaging, and exhibited poor correlation with fungal spore concentrations, which may be due to the detection of bacterial and non-biological fluorescent particles. Cladosporium spp., which are among the most abundant fungal spores in many terrestrial environments, were not correlated with any of the real-time fluorescence channels, suggesting that the real-time fluorescence instruments are relatively insensitive to PBAP classes with dark, highly absorptive cell walls. Fluorescence microscopy images of cascade impactor plates showed large numbers of coarse-mode particles consistent with the morphology and weak fluorescence expected of sea salt. Some of these particles were attached to biological cells, suggesting that a marine source influenced the PBAPs observed at the site and that the ocean may be an important contributor to PBAP loadings in coastal environments.
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Processes Affecting the Variability of Fluorescence Signals from Benthic Targets in Shallow Waters
1998-09-30
analysis of zooxanthellae isolated from coral samples. We examined fluorescence lifetimes from benthic targets using femtosecond laser based Single...a temporal resolution 5 ps. The laser set-up was employed for laboratory studies of fluorescence lifetimes from model targets such as zooxanthellae ...seagrasses. Over 200 measurements on isolated zooxanthellae were conducted with a bench-top FRR fluorometer and Phase Shift Fluorometer. During the CoBOP-98
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Parametric models to compute tryptophan fluorescence wavelengths from classical protein simulations.
Lopez, Alvaro J; Martínez, Leandro
2018-02-26
Fluorescence spectroscopy is an important method to study protein conformational dynamics and solvation structures. Tryptophan (Trp) residues are the most important and practical intrinsic probes for protein fluorescence due to the variability of their fluorescence wavelengths: Trp residues emit in wavelengths ranging from 308 to 360 nm depending on the local molecular environment. Fluorescence involves electronic transitions, thus its computational modeling is a challenging task. We show that it is possible to predict the wavelength of emission of a Trp residue from classical molecular dynamics simulations by computing the solvent-accessible surface area or the electrostatic interaction between the indole group and the rest of the system. Linear parametric models are obtained to predict the maximum emission wavelengths with standard errors of the order 5 nm. In a set of 19 proteins with emission wavelengths ranging from 308 to 352 nm, the best model predicts the maximum wavelength of emission with a standard error of 4.89 nm and a quadratic Pearson correlation coefficient of 0.81. These models can be used for the interpretation of fluorescence spectra of proteins with multiple Trp residues, or for which local Trp environmental variability exists and can be probed by classical molecular dynamics simulations. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.
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Topography of Cells Revealed by Variable-Angle Total Internal Reflection Fluorescence Microscopy.
Cardoso Dos Santos, Marcelina; Déturche, Régis; Vézy, Cyrille; Jaffiol, Rodolphe
2016-09-20
We propose an improved version of variable-angle total internal reflection fluorescence microscopy (vaTIRFM) adapted to modern TIRF setup. This technique involves the recording of a stack of TIRF images, by gradually increasing the incident angle of the light beam on the sample. A comprehensive theory was developed to extract the membrane/substrate separation distance from fluorescently labeled cell membranes. A straightforward image processing was then established to compute the topography of cells with a nanometric axial resolution, typically 10-20 nm. To highlight the new opportunities offered by vaTIRFM to quantify adhesion process of motile cells, adhesion of MDA-MB-231 cancer cells on glass substrate coated with fibronectin was examined. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.
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NASA Astrophysics Data System (ADS)
Einstein, Gnanatheepam; Udayakumar, Kanniyappan; Aruna, Prakasarao; Ganesan, Singaravelu
2017-03-01
Fluorescence of Protein has been widely used in diagnostic oncology for characterizing cellular metabolism. However, the intensity of fluorescence emission is affected due to the absorbers and scatterers in tissue, which may lead to error in estimating exact protein content in tissue. Extraction of intrinsic fluorescence from measured fluorescence has been achieved by different methods. Among them, Monte Carlo based method yields the highest accuracy for extracting intrinsic fluorescence. In this work, we have attempted to generate a lookup table for Monte Carlo simulation of fluorescence emission by protein. Furthermore, we fitted the generated lookup table using an empirical relation. The empirical relation between measured and intrinsic fluorescence is validated using tissue phantom experiments. The proposed relation can be used for estimating intrinsic fluorescence of protein for real-time diagnostic applications and thereby improving the clinical interpretation of fluorescence spectroscopic data.
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NASA Astrophysics Data System (ADS)
Murphy, K.; Stedmon, C. A.; Wunsch, U.
2017-12-01
The study of dissolved organic matter in aquatic milieu frequently involves measuring and interpreting fluorescence excitation emission matrices (EEMs) as a proxy for studying the total organic matter pool. Parallel Factor Analysis (PARAFAC) is used widely to identify and track independent organic matter fractions. This approach assumes that each EEM reflects the combined fluorescence signal from a limited number of unique, non-interacting chemical components, which are determined via a fitting algorithm. During the past fifteen years, considerable progress in understanding dissolved organic matter fluorescence has been achieved with the aid of PARAFAC; however, very few identical or ubiquitous fluorescence spectra have been independently identified. We studied the influence of wavelength selection on PARAFAC models and found this factor to have a decisive impact on PARAFAC spectra despite receiving little attention in most studies. Because large, chemically-diverse datasets may be too complex to analyse with PARAFAC, we are exploring novel methods for increasing variability in small datasets in order to reduce biases and increase interpretability. Our results suggest that spectral variability in PARAFAC models between studies are in many cases due to artefacts that could be minimised by careful experimental and modelling approaches.
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Cheng, Dan-Dan; Zhang, Zi-Shan; Sun, Xing-Bin; Zhao, Min; Sun, Guang-Yu; Chow, Wah Soon
2016-01-25
Pseudomonas syringae pv. tabaci (Pst), which is the pathogen responsible for tobacco wildfire disease, has received considerable attention in recent years. The objective of this study was to clarify the responses of photosystem I (PSI) and photosystem II (PSII) to Pst infection in tobacco leaves. The net photosynthetic rate (Pn) and carboxylation efficiency (CE) were inhibited by Pst infection. The normalized relative variable fluorescence at the K step (W k) and the relative variable fluorescence at the J step (V J) increased while the maximal quantum yield of PSII (F v/F m) and the density of Q A-reducing PSII reaction centers per cross section (RC/CSm) decreased, indicating that the reaction centers, and the donor and acceptor sides of PSII were all severely damaged after Pst infection. The PSI activity decreased as the infection progressed. Furthermore, we observed a considerable overall degradation of PsbO, D1, PsaA proteins and an over-accumulation of reactive oxygen species (ROS). Photoinhibition and photoinhibition-like damage were observed under light and dark conditions, respectively, after Pst infection of tobacco leaves. The damage was greater in the dark. ROS over-accumulation was not the primary cause of the photoinhibition and photoinhibition-like damage. The PsbO, D1 and PsaA proteins appear to be the targets during Pst infection under light and dark conditions.
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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 SO42− 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 SO42−, 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 SO42−. To avoid such interference, the backup Raman spectroscopy system with λex = 785 nm was employed to detect SO42− 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 SO42− in the ocean. PMID:27420071
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Protoporphyrin IX fluorescence as potential indicator of psoriasis severity and progression.
Wang, Bo; Xu, Yu-Ting; Zhang, Li; Zheng, Jie; Sroka, Ronald; Wang, Hong-Wei; Wang, Xiu-Li
2017-09-01
In psoriatic lesions, fluorescence diagnosis with blue light can detect protoporphyrin IX accumulation, especially after topical 5-aminolaevulinic acid (ALA) application. However, variable fluorescence distributions, interpersonal variations and long incubation time limit its wide application in clinic. This study is aimed to identify a consistent and convenient method to facilitate diagnosis and evaluation of psoriatic lesions. 104 psoriatic lesions from 30 patients were evaluated. Single lesion PSI scoring and fluorescence by macrospectrofluorometry were recorded on each lesion before and after treatment with narrow-band UVB. Punctate red fluorescence, emitted mainly by protoporphyrin IX, is observed in some psoriatic lesions. According to psoriasis severity index, fluorescence-positive lesions are more severe than lesions without fluorescence. We found a significant positive correlation between psoriasis severity and fluorescence intensity from protoporphyrin IX. Protoporphyrin IX-induced red fluorescence can be used as a novel and convenient approach for psoriasis diagnosis and progression evaluation. Copyright © 2017. Published by Elsevier B.V.
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Yu, Shaohui; Xiao, Xue; Ding, Hong; Xu, Ge; Li, Haixia; Liu, Jing
2017-08-05
The quantitative analysis is very difficult for the emission-excitation fluorescence spectroscopy of multi-component mixtures whose fluorescence peaks are serious overlapping. As an effective method for the quantitative analysis, partial least squares can extract the latent variables from both the independent variables and the dependent variables, so it can model for multiple correlations between variables. However, there are some factors that usually affect the prediction results of partial least squares, such as the noise, the distribution and amount of the samples in calibration set etc. This work focuses on the problems in the calibration set that are mentioned above. Firstly, the outliers in the calibration set are removed by leave-one-out cross-validation. Then, according to two different prediction requirements, the EWPLS method and the VWPLS method are proposed. The independent variables and dependent variables are weighted in the EWPLS method by the maximum error of the recovery rate and weighted in the VWPLS method by the maximum variance of the recovery rate. Three organic matters with serious overlapping excitation-emission fluorescence spectroscopy are selected for the experiments. The step adjustment parameter, the iteration number and the sample amount in the calibration set are discussed. The results show the EWPLS method and the VWPLS method are superior to the PLS method especially for the case of small samples in the calibration set. Copyright © 2017 Elsevier B.V. All rights reserved.
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Girgis, Adel S; Basta, Altaf H; El-Saied, Houssni; Mohamed, Mohamed A; Bedair, Ahmad H; Salim, Ahmad S
2018-03-01
A variety of fluorescence-active fluorinated pyrazolines 13-33 was synthesized in good yields through cyclocondensation reaction of propenones 1-9 with aryl hydrazines 10-12 . Some of the synthesized compounds provided promising fluorescence properties with quantum yield ( Φ ) higher than that of quinine sulfate (standard reference). Quantitative structure-property relationship studies were undertaken supporting the exhibited fluorescence properties and estimating the parameters governing properties. Five synthesized fluorescence-active pyrazolines ( 13 , 15 , 18 , 19 and 23 ) with variable Φ were selected for treating two types of paper sheets (Fabriano and Bible paper). These investigated fluorescence compounds, especially compounds 19 and 23 , provide improvements in strength properties of paper sheets. Based on the observed performance they can be used as markers in security documents.
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Girgis, Adel S.; El-Saied, Houssni; Mohamed, Mohamed A.; Bedair, Ahmad H.; Salim, Ahmad S.
2018-01-01
A variety of fluorescence-active fluorinated pyrazolines 13–33 was synthesized in good yields through cyclocondensation reaction of propenones 1–9 with aryl hydrazines 10–12. Some of the synthesized compounds provided promising fluorescence properties with quantum yield (Φ) higher than that of quinine sulfate (standard reference). Quantitative structure–property relationship studies were undertaken supporting the exhibited fluorescence properties and estimating the parameters governing properties. Five synthesized fluorescence-active pyrazolines (13, 15, 18, 19 and 23) with variable Φ were selected for treating two types of paper sheets (Fabriano and Bible paper). These investigated fluorescence compounds, especially compounds 19 and 23, provide improvements in strength properties of paper sheets. Based on the observed performance they can be used as markers in security documents. PMID:29657796
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NASA Astrophysics Data System (ADS)
Girgis, Adel S.; Basta, Altaf H.; El-Saied, Houssni; Mohamed, Mohamed A.; Bedair, Ahmad H.; Salim, Ahmad S.
2018-03-01
A variety of fluorescence-active fluorinated pyrazolines 13-33 was synthesized in good yields through cyclocondensation reaction of propenones 1-9 with aryl hydrazines 10-12. Some of the synthesized compounds provided promising fluorescence properties with quantum yield (Φ) higher than that of quinine sulfate (standard reference). Quantitative structure-property relationship studies were undertaken supporting the exhibited fluorescence properties and estimating the parameters governing properties. Five synthesized fluorescence-active pyrazolines (13, 15, 18, 19 and 23) with variable Φ were selected for treating two types of paper sheets (Fabriano and Bible paper). These investigated fluorescence compounds, especially compounds 19 and 23, provide improvements in strength properties of paper sheets. Based on the observed performance they can be used as markers in security documents.
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Oukarroum, Abdallah; El Madidi, Saïd; Strasser, Reto J
2016-08-01
The objective of this study was to differentiate the heat tolerance in ten varieties of barley (Hordeum vulgare L.) originating from Morocco. Five modern varieties and five landraces (local varieties) collected at five different geographical localities in the south of Morocco were investigated in the present study. After two weeks of growth, detached leaves were short term exposure to various temperatures (25, 30, 35, 40, and 45 °C) for 10 min in the dark. Two chlorophyll a fluorescence parameters derived from chlorophyll a fluorescence transient (OKJIP) (performance index (PIABS) and relative variable fluorescence at the K-step (VK)) were analysed. Heat treatment had a significant effect on the PIABS and VK at 45 °C treatment and the analysis of variance for PIABS and VK is highly significant between all varieties. The slope of the relationship between logPIABS and VK named heat sensitivity index (HSI) was used to evaluate the thermotolerance of photosystem II (PSII) between the studied barley varieties. According to this approach, barley varieties were screened and ranked for improving heat tolerance. HSI was found to be a new indicator with regard to distinguishing heat tolerance of different barley cultivars. Copyright © 2016 Elsevier Masson SAS. All rights reserved.
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Comparative Phenotypical and Molecular Analyses of Arabidopsis Grown under Fluorescent and LED Light
Seiler, Franka; Soll, Jürgen; Bölter, Bettina
2017-01-01
Comparative analyses of phenotypic and molecular traits of Arabidopsis thaliana grown under standardised conditions is still a challenge using climatic devices supplied with common light sources. These are in most cases fluorescent lights, which have several disadvantages such as heat production at higher light intensities, an invariable spectral output, and relatively rapid “ageing”. This results in non-desired variations of growth conditions and lowers the comparability of data acquired over extended time periods. In this study, we investigated the growth behaviour of Arabidopsis Col0 under different light conditions, applying fluorescent compared to LED lamps, and we conducted physiological as well as gene expression analyses. By changing the spectral composition and/or light intensity of LEDs we can clearly influence the growth behaviour of Arabidopsis and thereby study phenotypic attributes under very specific light conditions that are stable and reproducible, which is not necessarily given for fluorescent lamps. By using LED lights, we can also roughly mimic the sun light emission spectrum, enabling us to study plant growth in a more natural-like light set-up. We observed distinct growth behaviour under the different light regimes which was reflected by physiological properties of the plants. In conclusion, LEDs provide variable emission spectra for studying plant growth under defined, stable light conditions. PMID:28608805
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Fluorescence-based proxies for lignin in freshwater dissolved organic matter
Hernes, Peter J.; Bergamaschi, Brian A.; Eckard, Robert S.; Spencer, Robert G.M.
2009-01-01
Lignin phenols have proven to be powerful biomarkers in environmental studies; however, the complexity of lignin analysis limits the number of samples and thus spatial and temporal resolution in any given study. In contrast, spectrophotometric characterization of dissolved organic matter (DOM) is rapid, noninvasive, relatively inexpensive, requires small sample volumes, and can even be measured in situ to capture fine-scale temporal and spatial detail of DOM cycling. Here we present a series of cross-validated Partial Least Squares models that use fluorescence properties of DOM to explain up to 91% of lignin compositional and concentration variability in samples collected seasonally over 2 years in the Sacramento River/San Joaquin River Delta in California, United States. These models were subsequently used to predict lignin composition and concentration from fluorescence measurements collected during a diurnal study in the San Joaquin River. While modeled lignin composition remained largely unchanged over the diurnal cycle, changes in modeled lignin concentrations were much greater than expected and indicate that the sensitivity of fluorescence-based proxies for lignin may prove invaluable as a tool for selecting the most informative samples for detailed lignin characterization. With adequate calibration, similar models could be used to significantly expand our ability to study sources and processing of DOM in complex surface water systems.
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NASA Astrophysics Data System (ADS)
Wang, Huaiyou; Zhang, Miao; Lv, Qingluan; Yue, Ningning; Gong, Bin
2009-08-01
A new method for determining berberine has been established based on the principle of fluorescence quenching. The calibration curve was found to be linear between F0/ F and the concentration of berberine with the range of 3.00-20.0 μg mL -1. The detection limit was 0.51 μg mL -1 and the relative standard derivative was 0.18%. Effects of pH, foreign ions and the optimization of variables on the determination of berberine have been examined. The mechanism of the fluorescence quenching has been discussed. The binding constant and the number of binding sites were 1.70 × 10 6 L mol -1 and 1.14, respectively. The data, Δ H = 42.71 kJ mol -1, Δ S = 264.3 J K -1 mol -1 and the mean value Δ G = -39.65 kJ mol -1 were estimated which showed that the reaction was spontaneous and endothermic. The main binding force was hydrophobic force because both Δ H and Δ S were positive.
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"Quenchbodies": quench-based antibody probes that show antigen-dependent fluorescence.
Abe, Ryoji; Ohashi, Hiroyuki; Iijima, Issei; Ihara, Masaki; Takagi, Hiroaki; Hohsaka, Takahiro; Ueda, Hiroshi
2011-11-02
Here, we describe a novel reagentless fluorescent biosensor strategy based on the antigen-dependent removal of a quenching effect on a fluorophore attached to antibody domains. Using a cell-free translation-mediated position-specific protein labeling system, we found that an antibody single chain variable region (scFv) that had been fluorolabeled at the N-terminal region showed a significant antigen-dependent fluorescence enhancement. Investigation of the enhancement mechanism by mutagenesis of the carboxytetramethylrhodamine (TAMRA)-labeled anti-osteocalcin scFv showed that antigen-dependency was dependent on semiconserved tryptophan residues near the V(H)/V(L) interface. This suggested that the binding of the antigen led to the interruption of a quenching effect caused by the proximity of tryptophan residues to the linker-tagged fluorophore. Using TAMRA-scFv, many targets including peptides, proteins, and haptens including morphine-related drugs could be quantified. Similar or higher sensitivities to those observed in competitive ELISA were obtained, even in human plasma. Because of its versatility, this "quenchbody" is expected to have a range of applications, from in vitro diagnostics, to imaging of various targets in situ.
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Piniak, G.A.; Storlazzi, C.D.
2008-01-01
Terrigenous sediment in the nearshore environment can pose both acute and chronic stresses to coral reefs. The reef flat off southern Molokai, Hawaii, typically experiences daily turbidity events, in which trade winds and tides combine to resuspend terrigenous sediment and transport it alongshore. These chronic turbidity events could play a role in restricting coral distribution on the reef flat by reducing the light available for photosynthesis. This study describes the effects of these turbidity events on the Hawaiian reef coral Montipora capitata using in situ diurnal measurements of turbidity, light levels, and chlorophyll fluorescence yield via pulse-amplitude-modulated (PAM) fluorometry. Average surface irradiance was similar in the morning and the afternoon, while increased afternoon turbidity resulted in lower subsurface irradiance, higher fluorescence yield (??F/Fm???), and lower relative electron transport rates (rETR). Model calculations based on observed light extinction coeffecients suggest that in the absence of turbidity events, afternoon subsurface irradiances would be 1.43 times higher than observed, resulting in rETR for M. capitata that are 1.40 times higher.
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Processes Affecting the Variability of Fluorescence Signals from Benthic Targets in Shallow Waters
1999-09-30
isolated green fluorescent proteins from a variety of cnidarians and characterized their spectral signatures and biochemical characteristics. RESULTS...types of GFP-like fluorophores are present in Cnidarians . The first one had the only excitation band centered at ca. 495 nm; the second type had two
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Spectral and Temporal Laser Fluorescence Analysis Such as for Natural Aquatic Environments
NASA Technical Reports Server (NTRS)
Chekalyuk, Alexander (Inventor)
2015-01-01
An Advanced Laser Fluorometer (ALF) can combine spectrally and temporally resolved measurements of laser-stimulated emission (LSE) for characterization of dissolved and particulate matter, including fluorescence constituents, in liquids. Spectral deconvolution (SDC) analysis of LSE spectral measurements can accurately retrieve information about individual fluorescent bands, such as can be attributed to chlorophyll-a (Chl-a), phycobiliprotein (PBP) pigments, or chromophoric dissolved organic matter (CDOM), among others. Improved physiological assessments of photosynthesizing organisms can use SDC analysis and temporal LSE measurements to assess variable fluorescence corrected for SDC-retrieved background fluorescence. Fluorescence assessments of Chl-a concentration based on LSE spectral measurements can be improved using photo-physiological information from temporal measurements. Quantitative assessments of PBP pigments, CDOM, and other fluorescent constituents, as well as basic structural characterizations of photosynthesizing populations, can be performed using SDC analysis of LSE spectral measurements.
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Physical and geochemical drivers of CDOM variability near a natural seep site in the Gulf of Mexico
NASA Astrophysics Data System (ADS)
Edwards, C. R.; Powers, L.; Medeiros, P. M.
2016-02-01
Colored dissolved organic matter (CDOM) on the continental shelf and slope can serve as a marker for fresh water influence, indicate the presence of hydrocarbons, and provide important clues about nutrient content and organic matter cycling. Autonomous underwater vehicles such as gliders allow for subsurface measurement of CDOM fluorescence for weeks to months; these time series may be especially valuable in the northern Gulf of Mexico, where CDOM inputs of both terrestrial and oil and gas sources can be significant. Data from a recent glider deployment near a natural seep site (GC600) on the continental slope over 180km from shore suggest simultaneous influence of Mississippi plume water and hydrocarbon inputs in the upper 200m, with variability in fluorescence at a range of vertical and temporal scales. We will explore patterns in spatial and temporal variability of glider-measured hydrography, dissolved oxygen, and bio-optical data (CDOM, chlorophyll-a, backscatter fluorescence), and use their combination to infer a terrigenous and/or fossil fuel source(s). Taking advantage of a combination of satellite sea surface temperature, ocean color, wind, and data from moored and mobile platforms, we will examine physical controls on transport and vertical mixing of CDOM and the potential role of nonlinear mesoscale eddies, which can trap water in their interior and may transport river- or hydrocarbon-derived CDOM over long distances. The combined data set will be used to consider and potentially constrain the effect of photodegradation and other biogeochemical causes for CDOM fluorescence variability in the upper 200m.
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Kalcsits, Lee A.
2016-01-01
Calcium and potassium are essential for cell signaling, ion homeostasis and cell wall strength in plants. Unlike nutrients such as nitrogen and potassium, calcium is immobile in plants. Localized calcium deficiencies result in agricultural losses; particularly for fleshy horticultural crops in which elemental imbalances in fruit contribute to the development of physiological disorders such as bitter pit in apple and cork spot in pear. Currently, elemental analysis of plant tissue is destructive, time consuming and costly. This is a limitation for nutrition studies related to calcium in plants. Handheld portable x-ray fluorescence (XRF) can be used to non-destructively measure elemental concentrations. The main objective was to test if handheld XRF can be used for semi-quantitative calcium and potassium analysis of in-tact apple and pear. Semi-quantitative measurements for individual fruit were compared to results obtained from traditional lab analysis. Here, we observed significant correlations between handheld XRF measurements of calcium and potassium and concentrations determined using MP-AES lab analysis. Pearson correlation coefficients ranged from 0.73 and 0.97. Furthermore, measuring apple and pear using handheld XRF identified spatial variability in calcium and potassium concentrations on the surface of individual fruit. This variability may contribute to the development of localized nutritional imbalances. This highlights the importance of understanding spatial and temporal variability in elemental concentrations in plant tissue. Handheld XRF is a relatively high-throughput approach for measuring calcium and potassium in plant tissue. It can be used in conjunction with traditional lab analysis to better understand spatial and temporal patterns in calcium and potassium uptake and distribution within an organ, plant or across the landscape. PMID:27092160
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NASA Astrophysics Data System (ADS)
Plank, David M.; Sussman, Mark A.
2005-06-01
Altered intracellular Ca2+ dynamics are characteristically observed in cardiomyocytes from failing hearts. Studies of Ca2+ handling in myocytes predominantly use Fluo-3 AM, a visible light excitable Ca2+ chelating fluorescent dye in conjunction with rapid line-scanning confocal microscopy. However, Fluo-3 AM does not allow for traditional ratiometric determination of intracellular Ca2+ concentration and has required the use of mathematic correction factors with values obtained from separate procedures to convert Fluo-3 AM fluorescence to appropriate Ca2+ concentrations. This study describes methodology to directly measure intracellular Ca2+ levels using inactivated, Fluo-3-AM-loaded cardiomyocytes equilibrated with Ca2+ concentration standards. Titration of Ca2+ concentration exhibits a linear relationship to increasing Fluo-3 AM fluorescence intensity. Images obtained from individual myocyte confocal scans were recorded, average pixel intensity values were calculated, and a plot is generated relating the average pixel intensity to known Ca2+ concentrations. These standard plots can be used to convert transient Ca2+ fluorescence obtained with experimental cells to Ca2+ concentrations by linear regression analysis. Standards are determined on the same microscope used for acquisition of unknown Ca2+ concentrations, simplifying data interpretation and assuring accuracy of conversion values. This procedure eliminates additional equipment, ratiometric imaging, and mathematic correction factors and should be useful to investigators requiring a straightforward method for measuring Ca2+ concentrations in live cells using Ca2+-chelating dyes exhibiting variable fluorescence intensity.
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NASA Astrophysics Data System (ADS)
Blaen, Phillip; Kurz, Marie; Knapp, Julia; Mendoza-Lera, Clara; Lee-Cullin, Joe; Klaar, Megan; Drummond, Jen; Jaeger, Anna; Zarnetske, Jay; Lewandowski, Joerg; Marti, Eugenia; Ward, Adam; Fleckenstein, Jan; Datry, Thibault; Larned, Scott; Krause, Stefan
2016-04-01
Nutrient concentrations in surface waters and groundwaters are increasing in many agricultural catchments worldwide as a result of anthropogenic activities. Increasing geomorphological heterogeneity in river channels may help to attenuate nutrient pollution by facilitating water exchange fluxes with the hyporheic zone; a site of intense microbial activity where biogeochemical transformation rates (e.g. denitrification) can be high. However, the controls on spatial variability in biogeochemical cycling, particularly at scales relevant for river managers, are not well understood. Here, we aimed to assess: 1) how differences in geomorphological heterogeneity control river solute transport and rates of biogeochemical cycling at sub-reach scales (102 m); and 2) the relative magnitude of these differences versus those relating to reach scale substrate variability (103 m). We used the reactive 'smart' tracer resazurin (Raz), a weakly fluorescent dye that transforms to highly fluorescent resorufin (Rru) under mildly reducing conditions, as a proxy to assess rates of biogeochemical cycling in a lowland river in southern England. Solute tracer tests were conducted in two reaches with contrasting substrates: one sand-dominated and the other gravel-dominated. Each reach was divided into sub-reaches that varied in geomorphic complexity (e.g. by the presence of pool-riffle sequences or the abundance of large woody debris). Slug injections of Raz and the conservative tracer fluorescein were conducted in each reach during baseflow conditions (Q ≈ 80 L/s) and breakthrough curves monitored using in-situ fluorometers. Preliminary results indicate overall Raz:Rru transformation rates in the gravel-dominated reach were more than 50% higher than those in the sand-dominated reach. However, high sub-reach variability in Raz:Rru transformation rates and conservative solute transport parameters suggests small-scale targeted management interventions to alter geomorphic heterogeneity may be effective in creating hotspots of river biogeochemical cycling and nutrient load attenuation.
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Observations of Ocean Primary Productivity Using MODIS
NASA Technical Reports Server (NTRS)
Esaias, Wayne E.; Abbott, Mark R.; Koblinsky, Chester J. (Technical Monitor)
2001-01-01
Measuring the magnitude and variability of oceanic net primary productivity (NPP) represents a key advancement toward our understanding of the dynamics of marine ecosystems and the role of the ocean in the global carbon cycle. MODIS observations make two new contributions in addition to continuing the bio-optical time series begun with Orbview-2's SeaWiFS sensor. First, MODIS provides weekly estimates of global ocean net primary productivity on weekly and annual time periods, and annual empirical estimates of carbon export production. Second, MODIS provides additional insight into the spatial and temporal variations in photosynthetic efficiency through the direct measurements of solar-stimulated chlorophyll fluorescence. The two different weekly productivity indexes (first developed by Behrenfeld & Falkowski and by Yoder, Ryan and Howard) are used to derive daily productivity as a function of chlorophyll biomass, incident daily surface irradiance, temperature, euphotic depth, and mixed layer depth. Comparisons between these two estimates using both SeaWiFS and MODIS data show significant model differences in spatial distribution after allowance for the different integration depths. Both estimates are strongly dependence on the accuracy of the chlorophyll determination. In addition, an empirical approach is taken on annual scales to estimate global NPP and export production. Estimates of solar stimulated fluorescence efficiency from chlorophyll have been shown to be inversely related to photosynthetic efficiency by Abbott and co-workers. MODIS provides the first global estimates of oceanic chlorophyll fluorescence, providing an important proof of concept. MODIS observations are revealing spatial patterns of fluorescence efficiency which show expected variations with phytoplankton photo-physiological parameters as measured during in-situ surveys. This has opened the way for research into utilizing this information to improve our understanding of oceanic NPP variability. Deriving the ocean bio-optical properties places severe demands on instrument performance (especially band to band precision) and atmospheric correction. Improvements in MODIS instrument characterization and calibration over the first 16 mission months have greatly improved the accuracy of the chlorophyll input fields and FLH, and therefore the estimates of NPP and fluorescence efficiency. Annual estimates now show the oceanic NPP accounts for 40-50% of the global total NPP, with significant interannual variations related to large scale ocean processes. Spatial variations in ocean NPP, and exported production, have significant effects on exchange of CO2 between the ocean and atmosphere. Further work is underway to improve both the primary productivity model functions, and to refine our understanding of the relationships between fluorescence efficiency and NPP estimates. We expect that the MODIS instruments will prove extremely useful in assessing the time dependencies of oceanic carbon uptake and effects of iron enrichment, within the global carbon cycle.
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Cortesi, Marilisa; Bandiera, Lucia; Pasini, Alice; Bevilacqua, Alessandro; Gherardi, Alessandro; Furini, Simone; Giordano, Emanuele
2017-01-01
Quantifying gene expression at single cell level is fundamental for the complete characterization of synthetic gene circuits, due to the significant impact of noise and inter-cellular variability on the system's functionality. Commercial set-ups that allow the acquisition of fluorescent signal at single cell level (flow cytometers or quantitative microscopes) are expensive apparatuses that are hardly affordable by small laboratories. A protocol that makes a standard optical microscope able to acquire quantitative, single cell, fluorescent data from a bacterial population transformed with synthetic gene circuitry is presented. Single cell fluorescence values, acquired with a microscope set-up and processed with custom-made software, are compared with results that were obtained with a flow cytometer in a bacterial population transformed with the same gene circuitry. The high correlation between data from the two experimental set-ups, with a correlation coefficient computed over the tested dynamic range > 0.99, proves that a standard optical microscope- when coupled with appropriate software for image processing- might be used for quantitative single-cell fluorescence measurements. The calibration of the set-up, together with its validation, is described. The experimental protocol described in this paper makes quantitative measurement of single cell fluorescence accessible to laboratories equipped with standard optical microscope set-ups. Our method allows for an affordable measurement/quantification of intercellular variability, whose better understanding of this phenomenon will improve our comprehension of cellular behaviors and the design of synthetic gene circuits. All the required software is freely available to the synthetic biology community (MUSIQ Microscope flUorescence SIngle cell Quantification).
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A Neuron-Based Screening Platform for Optimizing Genetically-Encoded Calcium Indicators
Schreiter, Eric R.; Hasseman, Jeremy P.; Tsegaye, Getahun; Fosque, Benjamin F.; Behnam, Reza; Shields, Brenda C.; Ramirez, Melissa; Kimmel, Bruce E.; Kerr, Rex A.; Jayaraman, Vivek; Looger, Loren L.; Svoboda, Karel; Kim, Douglas S.
2013-01-01
Fluorescent protein-based sensors for detecting neuronal activity have been developed largely based on non-neuronal screening systems. However, the dynamics of neuronal state variables (e.g., voltage, calcium, etc.) are typically very rapid compared to those of non-excitable cells. We developed an electrical stimulation and fluorescence imaging platform based on dissociated rat primary neuronal cultures. We describe its use in testing genetically-encoded calcium indicators (GECIs). Efficient neuronal GECI expression was achieved using lentiviruses containing a neuronal-selective gene promoter. Action potentials (APs) and thus neuronal calcium levels were quantitatively controlled by electrical field stimulation, and fluorescence images were recorded. Images were segmented to extract fluorescence signals corresponding to individual GECI-expressing neurons, which improved sensitivity over full-field measurements. We demonstrate the superiority of screening GECIs in neurons compared with solution measurements. Neuronal screening was useful for efficient identification of variants with both improved response kinetics and high signal amplitudes. This platform can be used to screen many types of sensors with cellular resolution under realistic conditions where neuronal state variables are in relevant ranges with respect to timing and amplitude. PMID:24155972
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Green, J Marshall; Sabino, Jennifer; Fleming, Mark; Valerio, Ian
2015-03-01
In the recent Iraq and Afghanistan conflicts, survival rates from complex battlefield injuries have continued to improve. The resulting war-related wounds are challenging, with confounding issues making assessment of tissue perfusion subjective and variable. This review discusses the utility of intraoperative fluorescence angiography, and its usefulness as an objective tool to evaluate the perfusion of tissues in the face of complex war-related injuries. A retrospective review of all war-related traumatic and reconstructive cases employing intraoperative indocyanine green laser angiography (ICGLA) was performed. Data analyzed included indication for use, procedure success/failure rates, modifications performed, and perfusion-related complications. Anatomical regions assessed were extremity, head and neck, truncal, and intra-abdominal viscera. The endpoint of specific interest involved the decision for additional debridement of poorly perfused tissue, as based on the ICGLA findings. Over a 3-year period, this study examined 123 extremity soft tissue flaps, 41 extremity injuries including amputation and/or amputation revision cases, 13 craniofacial flaps, and 9 truncal/abdomen/gastrointestinal cases in which ICGLA was utilized to assess tissue perfusion and viability. A total of 35 (18.8%) of cases employing ICGLA required intraoperative modifications to address perfusion-related issues. Intraoperative fluorescent angiography is an objective, useful tool to assess various war-related traumatic injuries. This study expands on prior cited indications for ICGLA to include (1) guiding debridement in heavily contaminated wounds, (2) providing improved assessment of avulsion soft tissue injuries, (3) allowing for rapid detection of vascular and/or microvascular compromise in soft tissue and osseous flap reconstructions, (4) reducing and preventing perfusion-related complications in trauma, amputation closures, and reconstruction procedures, (5) contributing to better outcomes in certain complex orthopedic and composite tissue injuries, and (6) enabling improved postoperative wound and reconstruction assessment in those cases of perfusion-related issues that arise within a delayed setting. Reprint & Copyright © 2015 Association of Military Surgeons of the U.S.
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Erlandsen, Stanley L; Jarroll, Edward; Wallis, Peter; van Keulen, Harry
2005-08-01
In this study, we describe the development of fluorescent oligonucleotide probes to variable regions in the small subunit of 16S rRNA in three distinct Giardia species. Sense and antisense probes (17-22 mer) to variable regions 1, 3, and 8 were labeled with digoxygenin or selected fluorochomes (FluorX, Cy3, or Cy5). Optimal results were obtained with fluorochome-labeled oligonucleotides for detection of rRNA in Giardia cysts. Specificity of fluorescent in situ hybridization (FISH) was shown using RNase digestion and high stringency to diminish the hybridization signal, and oligonucleotide probes for rRNA in Giardia lamblia, Giardia muris, and Giardia ardeae were shown to specifically stain rRNA only within cysts or trophozoites of those species. The fluorescent oligonucleotide specific for rRNA in human isolates of Giardia was positive for ten different strains. A method for simultaneous FISH detection of cysts using fluorescent antibody (genotype marker) and two oligonucleotide probes (species marker) permitted visualization of G. lamblia and G. muris cysts in the same preparation. Testing of an environmental water sample revealed the presence of FISH-positive G. lamblia cysts with a specific rDNA probe for rRNA, while negative cysts were presumed to be of animal or bird origin.
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NASA Astrophysics Data System (ADS)
Piland, Geoffrey B.; Burdett, Jonathan J.; Hung, Tzu-Yao; Chen, Po-Hsun; Lin, Chi-Feng; Chiu, Tien-Lung; Lee, Jiun-Haw; Bardeen, Christopher J.
2014-05-01
Tetracene, a molecule that undergoes singlet fission, is deposited on Si with variable thickness LiF spacer layers. In agreement with earlier work (Hayashi et al., 1983 [10]), the fluorescence intensity of the tetracene greatly increases as the LiF thickness approaches 100 nm. This increase is partly due to a 30% increase in the prompt fluorescence decay time but mostly results from weaker coupling of the luminescence into the Si substrate. A decrease in the prompt fluorescence lifetime is observed as the tetracene thickness is increased on bare Si. We find no evidence for triplet energy transfer to the Si.
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Peterson, Richard B; Oja, Vello; Eichelmann, Hillar; Bichele, Irina; Dall'Osto, Luca; Laisk, Agu
2014-10-01
This work addresses the question of occurrence and function of photosystem II (PSII) in bundle sheath (BS) cells of leaves possessing NADP-malic enzyme-type C4 photosynthesis (Zea mays). Although no requirement for PSII activity in the BS has been established, several component proteins of PSII have been detected in BS cells of developing maize leaves exhibiting O2-insensitive photosynthesis. We used the basal fluorescence emissions of PSI (F 0I) and PSII (F 0II) as quantitative indicators of the respective relative photosystem densities. Chl fluorescence induction was measured simultaneously at 680 and 750 nm. In mature leaves, the F m(680)/F 0(680) ratio was 10.5 but less in immature leaves. We propose that the lower ratio was caused by the presence of a distinct non-variable component, F c, emitting at 680 and 750 nm. After F c was subtracted, the fluorescence of PSI (F 0I) was detected as a non-variable component at 750 nm and was undetectably low at 680 nm. Contents of Chls a and b were measured in addition to Chl fluorescence. The Chl b/(a + b) was relatively stable in developing sunflower leaves (0.25-0.26), but in maize it increased from 0.09 to 0.21 with leaf tissue age. In sunflower, the F 0I/(F 0I + F 0II) was 0.39 ± 0.01 independent of leaf age, but in maize, this parameter was 0.65 in young tissue of very low Chl content (20-50 mg m(-2)) falling to a stable level of 0.53 ± 0.01 at Chl contents >100 mg m(-2). The values of F 0I/(F 0I + F 0II) showed that in sunflower, excitation was partitioned between PSII and PSI in a ratio of 2:1, but the same ratio was 1:1 in the C4 plant. The latter is consistent with a PSII:PSI ratio of 2:1 in maize mesophyll cells and PSI only in BS cells (2:1:1 distribution). We suggest, moreover, that redox mediation of Chl synthesis, rather than protein accumulation, regulates photosystem assembly to ensure optimum excitation balance between functional PSII and PSI. Indeed, the apparent necessity for two Chls (a and b) may reside in their targeted functions in influencing accumulation of PSI and PSII, respectively, as opposed to their spectral differences.
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NASA Astrophysics Data System (ADS)
Wymore, Adam S.; Potter, Jody; Rodríguez-Cardona, Bianca; McDowell, William H.
2018-04-01
The advent of high-frequency in situ optical sensors provides new opportunities to study the biogeochemistry of dissolved organic matter (DOM) in aquatic ecosystems. We used fDOM (fluorescent dissolved organic matter) to examine the spatial and temporal variability in dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) across a heterogeneous stream network that varies in NO3- concentration. Across the ten study streams fDOM explained twice the variability in the concentration of DOC (r2 = 0.82) compared to DON (r2 = 0.39), which suggests that the N-rich fraction of DOM is either more variable in its sources or more bioreactive than the more stable C-rich fraction. Among sites, DON molar fluorescence was approximately 3x more variable than DOC molar fluorescence and was correlated with changes in inorganic N, indicating that DON is both more variable in composition as well as highly responsive to changes in inorganic N. Laboratory results also indicate that the fDOM sensors we used perform as well as the excitation-emission wavelength pair generally referred to as the "tryptophan-like" peak when measured under laboratory conditions. However, since neither the field sensor not the laboratory measurements explained a large percentage of variation in DON concentrations, challenges still remain for monitoring the ambient pool of dissolved organic nitrogen. Sensor networks provide new insights into the potential reactivity of DOM and the variability in DOC and DON biogeochemistry across sites. These insights are needed to build spatially explicit models describing organic matter dynamics and water quality.
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NASA Technical Reports Server (NTRS)
Tzortziou, Maria; Neale, Patrick J.; Megonigal, J. Patrick; Butterworth, Megan; Jaffe, Rudolf; Yamashita, Youhei
2010-01-01
Coastal wetlands are highly dynamic environments at the land-ocean interface where human activities, short-term physical forcings and intense episodic events result in high biological and chemical variability. Long being recognized as among the most productive ecosystems in the world, tidally-influenced coastal marshes are hot spots of biogeochemical transformation and exchange. High temporal resolution observations that we performed in several marsh-estuarine systems of the Chesapeake Bay revealed significant variability in water optical and biogeochemical characteristics at hourly time scales, associated with tidally-driven hydrology. Water in the tidal creek draining each marsh was sampled every hour during several semi-diurnal tidal cycles using ISCO automated samplers. Measurements showed that water leaving the marsh during ebbing tide was consistently enriched in dissolved organic carbon (DOC), frequently by more than a factor of two, compared to water entering the marsh during flooding tide. Estimates of DOC fluxes showed a net DOC export from the marsh to the estuary during seasons of both low and high biomass of marsh vegetation. Chlorophyll amounts were typically lower in the water draining the marsh, compared to that entering the marsh during flooding tide, suggesting that marshes act as transformers of particulate to dissolved organic matter. Moreover, detailed optical and compositional analyses demonstrated that marshes are important sources of optically and chemically distinctive, relatively complex, high molecular weight, aromatic-rich and highly colored dissolved organic compounds. Compared to adjacent estuarine waters, marsh-exported colored dissolved organic matter (CDOM) was characterized by considerably stronger absorption (more than a factor of three in some cases), larger DOC-specific absorption, lower exponential spectral slope, larger fluorescence signal, lower fluorescence per unit absorbance, and higher fluorescence at visible wavelengths. Observed patterns in water optical and biogeochemical variables were very consistent among different marsh systems and throughout the year, despite continued tidal exchange, implying rapid transformation of marsh DOM in the estuary through both photochemical and microbial processes. These findings illustrate the importance of tidal marsh ecosystems as sources, sinks and/or transformers of biologically important nutrients, carbon and colored dissolved organic compounds, and their influence on short-term biological, optical and biogeochemical variability in coastal waters.
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Potential of fluorescence spectroscopy for the characterisation of maple syrup flavours.
Panneton, Bernard; Clément, Alain; Lagacé, Luc
2013-10-01
Maple syrup has high maket value. It is produced in North East America from the heat-evaporated sap of Acer saccharum Marshall. For marketing purposes, there is interest in defining its flavour profile in a consistent and repeatable manner. An experiment was undertaken to explore the potential of autofluorescence of maple syrup induced at 275 and 360 nm to characterise flavours. A mixed data factor analysis revealed two independent groups of variables. One represents early season woody and late season empyreumatic flavours. The other is related to off-flavour, confectionery and maple flavours. Maple and confectionery flavours are subtle, difficult to distinguish and opposed to off-flavour. There were clear relationships among the two groups and fluorescence profiles. For each of the five basic flavours, discriminant models based on partial least squares regressions were developed. For each sample of syrup, flavours combined to form flavour profiles, and the results from the five discriminant models were aggregated to reproduce these profiles. For excitation at 275 nm, the woody/off-flavour and confectionery/empyreumatic/maple flavour profiles were classified correctly 86 and 78% of the time (cross-validation) respectively. Induced autofluorescence spectra were shown to contain information related to maple syrup flavours. This fluorescence-flavour relationship is not considered quantitative yet, and further research avenues are proposed. © 2013 Society of Chemical Industry.
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Physiological response of Pinus halepensis needles under ozone and water stress conditions.
Manes, Fausto; Donato, Eugenio; Vitale, Marcello
2001-10-01
The aim of this study was to evaluate how physiological processes of potted Pinus halepensis plants, grown under controlled conditions, were affected by ozone (O3) and/or water stress, integrating the gas exchange and biochemical data with fluorescence OJIP polyphasic transient data. Plants submitted to only water stress (T1) and with ozone (T3) showed a strong decrease in stomatal conductance and gas exchange, coinciding with a reduction of maximum yield of photochemistry (varphipo) and very negative values of leaf water potential. Simultaneously, a great increase of both PSII antenna size, indicated by absorption per reaction centre, and electron transport per reaction centre were found. The reduction of photosynthesis in the O3-treated plants (T2) by a slowing down of the Calvin cycle was supported by the increase of related fluorescence parameters such as relative variable fluorescence, heat de-excitation constant, energy de-excitation by spillover, and the decrease of varphipo. We suggest an antagonistic effect between the two stresses to explain the delayed ozone-induced decrease of stomatal conductance values for T3 with respect to T1 plants, by an alteration of the physiological mechanisms of stomatal opening, which involve the increase of intra-cellular free-calcium induced by ABA under co-occurring water shortage. We emphasise the importance of considering the intensity of the individual stress factor in studies concerning the interaction of stresses.
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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.
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Rochelle-Newall, E; Hulot, F D; Janeau, J L; Merroune, A
2014-01-01
Chromophoric dissolved organic matter (CDOM) fluorescence or absorption is often proposed as a rapid alternative to chemical methods for the estimation of bulk dissolved organic carbon (DOC) concentration in natural waters. However, the robustness of this method across a wide range of systems remains to be shown. We measured CDOM fluorescence and DOC concentration in four tropical freshwater and coastal environments (estuary and coastal, tropical shallow lakes, water from the freshwater lens of two small islands, and soil leachates). We found that although this method can provide an estimation of DOC concentration in sites with low variability in DOC and CDOM sources in systems where the variability of DOC and CDOM sources are high, this method should not be used as it will lead to errors in the estimation of the bulk DOC concentration.
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Küpper, Hendrik; Ferimazova, Naila; Šetlík, Ivan; Berman-Frank, Ilana
2004-01-01
We investigated interactions between photosynthesis and nitrogen fixation in the non-heterocystous marine cyanobacterium Trichodesmium IMS101 at the single-cell level by two-dimensional (imaging) microscopic measurements of chlorophyll fluorescence kinetics. Nitrogen fixation was closely associated with the appearance of cells with high basic fluorescence yield (F0), termed bright cells. In cultures aerated with normal air, both nitrogen fixation and bright cells appeared in the middle of the light phase. In cultures aerated with 5% oxygen, both processes occurred at a low level throughout most of the day. Under 50% oxygen, nitrogen fixation commenced at the beginning of the light phase but declined soon afterwards. Rapid reversible switches between fluorescence levels were observed, which indicated that the elevated F0 of the bright cells originates from reversible uncoupling of the photosystem II (PSII) antenna from the PSII reaction center. Two physiologically distinct types of bright cells were observed. Type I had about double F0 compared to the normal F0 in the dark phase and a PSII activity, measured as variable fluorescence (Fv = Fm − F0), similar to normal non-diazotrophic cells. Correlation of type I cells with nitrogen fixation, oxygen concentration, and light suggests that this physiological state is connected to an up-regulation of the Mehler reaction, resulting in oxygen consumption despite functional PSII. Type II cells had more than three times the normal F0 and hardly any PSII activity measurable by variable fluorescence. They did not occur under low-oxygen concentrations, but appeared under high-oxygen levels outside the diazotrophic period, suggesting that this state represents a reaction to oxidative stress not necessarily connected to nitrogen fixation. In addition to the two high-fluorescence states, cells were observed to reversibly enter a low-fluorescence state. This occurred mainly after a cell went through its bright phase and may represent a fluorescence-quenching recovery phase. PMID:15299119
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Weiss, Elliot L.; Schieber, Brian; Greg Mitchell, B.
2017-01-01
Abstract In this study we used fluorescence excitation and emission matrix spectroscopy, hydrographic data, and a self‐organizing map (SOM) analysis to assess the spatial distribution of labile and refractory fluorescent dissolved organic matter (FDOM) for the Chukchi and Beaufort Seas at the time of a massive under‐ice phytoplankton bloom during early summer 2011. Biogeochemical properties were assessed through decomposition of water property classes and sample classification that employed a SOM neural network‐based analysis which classified 10 clusters from 269 samples and 17 variables. The terrestrial, humic‐like component FDOM (ArC1, 4.98 ± 1.54 Quinine Sulfate Units (QSU)) and protein‐like component FDOM (ArC3, 1.63 ± 0.88 QSU) were found to have elevated fluorescence in the Lower Polar Mixed Layer (LPML) (salinity ~29.56 ± 0.76). In the LPML water mass, the observed contribution of meteoric water fraction was 17%, relative to a 12% contribution from the sea ice melt fraction. The labile ArC3‐protein‐like component (2.01 ± 1.92 QSU) was also observed to be elevated in the Pacific Winter Waters mass, where the under‐ice algal bloom was observed (~40–50 m). We interpreted these relationships to indicate that the accumulation and variable distribution of the protein‐like component on the shelf could be influenced directly by sea ice melt, transport, and mixing processes and indirectly by the in situ algal bloom and microbial activity. ArC5, corresponding to what is commonly considered marine humic FDOM, indicated a bimodal distribution with high values in both the freshest and saltiest waters. The association of ArC5 with deep, dense salty water is consistent with this component as refractory humic‐like FDOM, whereas our evidence of a terrestrial origin challenges this classic paradigm for this component. PMID:28989231
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NASA Astrophysics Data System (ADS)
Mendoza, Wilson G.; Weiss, Elliot L.; Schieber, Brian; Greg Mitchell, B.
2017-07-01
In this study we used fluorescence excitation and emission matrix spectroscopy, hydrographic data, and a self-organizing map (SOM) analysis to assess the spatial distribution of labile and refractory fluorescent dissolved organic matter (FDOM) for the Chukchi and Beaufort Seas at the time of a massive under-ice phytoplankton bloom during early summer 2011. Biogeochemical properties were assessed through decomposition of water property classes and sample classification that employed a SOM neural network-based analysis which classified 10 clusters from 269 samples and 17 variables. The terrestrial, humic-like component FDOM (ArC1, 4.98 ± 1.54 Quinine Sulfate Units (QSU)) and protein-like component FDOM (ArC3, 1.63 ± 0.88 QSU) were found to have elevated fluorescence in the Lower Polar Mixed Layer (LPML) (salinity 29.56 ± 0.76). In the LPML water mass, the observed contribution of meteoric water fraction was 17%, relative to a 12% contribution from the sea ice melt fraction. The labile ArC3-protein-like component (2.01 ± 1.92 QSU) was also observed to be elevated in the Pacific Winter Waters mass, where the under-ice algal bloom was observed ( 40-50 m). We interpreted these relationships to indicate that the accumulation and variable distribution of the protein-like component on the shelf could be influenced directly by sea ice melt, transport, and mixing processes and indirectly by the in situ algal bloom and microbial activity. ArC5, corresponding to what is commonly considered marine humic FDOM, indicated a bimodal distribution with high values in both the freshest and saltiest waters. The association of ArC5 with deep, dense salty water is consistent with this component as refractory humic-like FDOM, whereas our evidence of a terrestrial origin challenges this classic paradigm for this component.
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Pan-arctic trends in terrestrial dissolved organic matter from optical measurements
NASA Astrophysics Data System (ADS)
Mann, Paul; Spencer, Robert; Hernes, Peter; Six, Johan; Aiken, George; Tank, Suzanne; McClelland, James; Butler, Kenna; Dyda, Rachael; Holmes, Robert
2016-03-01
Climate change is causing extensive warming across arctic regions resulting in permafrost degradation, alterations to regional hydrology, and shifting amounts and composition of dissolved organic matter (DOM) transported by streams and rivers. Here, we characterize the DOM composition and optical properties of the six largest arctic rivers draining into the Arctic Ocean to examine the ability of optical measurements to provide meaningful insights into terrigenous carbon export patterns and biogeochemical cycling. The chemical composition of aquatic DOM varied with season, spring months were typified by highest lignin phenol and dissolved organic carbon (DOC) concentrations with greater hydrophobic acid content, and lower proportions of hydrophilic compounds, relative to summer and winter months. Chromophoric DOM (CDOM) spectral slope (S275-295) tracked seasonal shifts in DOM composition across river basins. Fluorescence and parallel factor analysis identified seven components across the six Arctic rivers. The ratios of 'terrestrial humic-like' versus 'marine humic-like' fluorescent components co-varied with lignin monomer ratios over summer and winter months, suggesting fluorescence may provide information on the age and degradation state of riverine DOM. CDOM absorbance (a350) proved a sensitive proxy for lignin phenol concentrations across all six river basins and over the hydrograph, enabling for the first time the development of a single pan-arctic relationship between a350 and terrigenous DOC (R2 = 0.93). Combining this lignin proxy with high-resolution monitoring of a350, pan-arctic estimates of annual lignin flux were calculated to range from 156 to 185 Gg, resulting in shorter and more constrained estimates of terrigenous DOM residence times in the Arctic Ocean (spanning 7 months to 2½ years). Furthermore, multiple linear regression models incorporating both absorbance and fluorescence variables proved capable of explaining much of the variability in lignin composition across rivers and seasons. Our findings suggest that synoptic, high-resolution optical measurements can provide improved understanding of northern high-latitude organic matter cycling and flux, and prove an important technique for capturing future climate-driven changes.
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Mendoza, Wilson G; Weiss, Elliot L; Schieber, Brian; Greg Mitchell, B
2017-07-01
In this study we used fluorescence excitation and emission matrix spectroscopy, hydrographic data, and a self-organizing map (SOM) analysis to assess the spatial distribution of labile and refractory fluorescent dissolved organic matter (FDOM) for the Chukchi and Beaufort Seas at the time of a massive under-ice phytoplankton bloom during early summer 2011. Biogeochemical properties were assessed through decomposition of water property classes and sample classification that employed a SOM neural network-based analysis which classified 10 clusters from 269 samples and 17 variables. The terrestrial, humic-like component FDOM (ArC1, 4.98 ± 1.54 Quinine Sulfate Units (QSU)) and protein-like component FDOM (ArC3, 1.63 ± 0.88 QSU) were found to have elevated fluorescence in the Lower Polar Mixed Layer (LPML) (salinity ~29.56 ± 0.76). In the LPML water mass, the observed contribution of meteoric water fraction was 17%, relative to a 12% contribution from the sea ice melt fraction. The labile ArC3-protein-like component (2.01 ± 1.92 QSU) was also observed to be elevated in the Pacific Winter Waters mass, where the under-ice algal bloom was observed (~40-50 m). We interpreted these relationships to indicate that the accumulation and variable distribution of the protein-like component on the shelf could be influenced directly by sea ice melt, transport, and mixing processes and indirectly by the in situ algal bloom and microbial activity. ArC5, corresponding to what is commonly considered marine humic FDOM, indicated a bimodal distribution with high values in both the freshest and saltiest waters. The association of ArC5 with deep, dense salty water is consistent with this component as refractory humic-like FDOM, whereas our evidence of a terrestrial origin challenges this classic paradigm for this component.
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Probing short-range protein Brownian motion in the cytoplasm of living cells.
Di Rienzo, Carmine; Piazza, Vincenzo; Gratton, Enrico; Beltram, Fabio; Cardarelli, Francesco
2014-12-23
The translational motion of molecules in cells deviates from what is observed in dilute solutions. Theoretical models provide explanations for this effect but with predictions that drastically depend on the nanoscale organization assumed for macromolecular crowding agents. A conclusive test of the nature of the translational motion in cells is missing owing to the lack of techniques capable of probing crowding with the required temporal and spatial resolution. Here we show that fluorescence-fluctuation analysis of raster scans at variable timescales can provide this information. By using green fluorescent proteins in cells, we measure protein motion at the unprecedented timescale of 1 μs, unveiling unobstructed Brownian motion from 25 to 100 nm, and partially suppressed diffusion above 100 nm. Furthermore, experiments on model systems attribute this effect to the presence of relatively immobile structures rather than to diffusing crowding agents. We discuss the implications of these results for intracellular processes.
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Fourman, Mitchell S; Mahjoub, Adel; Mandell, Jon B; Yu, Shibing; Tebbets, Jessica C; Crasto, Jared A; Alexander, Peter E; Weiss, Kurt R
2018-03-01
Current preclinical osteosarcoma (OS) models largely focus on quantifying primary tumor burden. However, most fatalities from OS are caused by metastatic disease. The quantification of metastatic OS currently relies on CT, which is limited by motion artifact, requires intravenous contrast, and can be technically demanding in the preclinical setting. We describe the ability for indocyanine green (ICG) fluorescence angiography to quantify primary and metastatic OS in a previously validated orthotopic, immunocompetent mouse model. (1) Can near-infrared ICG fluorescence be used to attach a comparable, quantitative value to the primary OS tumor in our experimental mouse model? (2) Will primary tumor fluorescence differ in mice that go on to develop metastatic lung disease? (3) Does primary tumor fluorescence correlate with tumor volume measured with CT? Six groups of 4- to 6-week-old immunocompetent Balb/c mice (n = 6 per group) received paraphyseal injections into their left hindlimb proximal tibia consisting of variable numbers of K7M2 mouse OS cells. A hindlimb transfemoral amputation was performed 4 weeks after injection with euthanasia and lung extraction performed 10 weeks after injection. Histologic examination of lung and primary tumor specimens confirmed ICG localization only within the tumor bed. Mice with visible or palpable tumor growth had greater hindlimb fluorescence (3.5 ± 2.3 arbitrary perfusion units [APU], defined as the fluorescence pixel return normalized by the detector) compared with those with a negative examination (0.71 ± 0.38 APU, -2.7 ± 0.5 mean difference, 95% confidence interval -3.7 to -1.8, p < 0.001). A strong linear trend (r = 0.81, p < 0.01) was observed between primary tumor and lung fluorescence, suggesting that quantitative ICG tumor fluorescence is directly related to eventual metastatic burden. We did not find a correlation (r = 0.04, p = 0.45) between normalized primary tumor fluorescence and CT volumetric measurements. We demonstrate a novel methodology for quantifying primary and metastatic OS in a previously validated, immunocompetent, orthotopic mouse model. Quantitative fluorescence of the primary tumor with ICG angiography is linearly related to metastatic burden, a relationship that does not exist with respect to clinical tumor size. This highlights the potential utility of ICG near-infrared fluorescence imaging as a valuable preclinical proof-of-concept modality. Future experimental work will use this model to evaluate the efficacy of novel OS small molecule inhibitors. Given the histologic localization of ICG to only the tumor bed, we envision the clinical use of ICG angiography as an intraoperative margin and tumor detector. Such a tool may be used as an alternative to intraoperative histology to confirm negative primary tumor margins or as a valuable tool for debulking surgeries in vulnerable anatomic locations. Because we have demonstrated the successful preservation of ICG in frozen tumor samples, future work will focus on blinded validation of this modality in observational human trials, comparing the ICG fluorescence of harvested tissue samples with fresh frozen pathology.
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NASA Astrophysics Data System (ADS)
Gu, L.
2017-12-01
In this study, we examine responses of sun-induced chlorophyll fluorescence to biological and environmental variations measured with a versatile Fluorescence Auto-Measurement Equipment (FAME). FAME was developed to automatically and continuously measure chlorophyll fluorescence (F) of a leaf, plant or canopy in both laboratory and field environments, excited by either artificial light source or sunlight. FAME is controlled by a datalogger and allows simultaneous measurements of environmental variables complementary to the F signals. A built-in communication system allows FAME to be remotely monitored and data-downloaded. Radiance and irradiance calibrations can be done online. FAME has been applied in a variety of environments, allowing an investigation of biological and environmental controls on F emission.
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NASA Astrophysics Data System (ADS)
Sonek, G. J.; Liu, Y.; Iturriaga, R. H.
1995-11-01
We describe the application of infrared optical tweezers to the in situ microparticle analysis of marine phytoplankton cells. A Nd:YAG laser (lambda=3D 1064 nm) trap is used to confine and manipulate single Nannochloris and Synechococcus cells in an enriched seawater medium while spectral fluorescence and Lorenz-Mie backscatter signals are simultaneously acquired under a variety of excitation and trapping conditions. Variations in the measured fluorescence intensities of chlorophyll a (Chl a) and phycoerythrin pigments in phytoplankton cells are observed. These variations are related, in part, to basic intrasample variability, but they also indicate that increasing ultraviolet-exposure time and infrared trapping power may have short-term effects on cellular physiology that are related to Chl a photobleaching and laser-induced heating, respectively. The use of optical tweezers to study the factors that affect marine cell physiology and the processes of absorption, scattering, and attenuation by individual cells, organisms, and particulate matter that contribute to optical closure on a microscopic scale are also described. (c)1995 Optical Society of America
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Myśliwa-Kurdziel, Beata; Solymosi, Katalin; Kruk, Jerzy; Böddi, Béla; Strzałka, Kazimierz
2007-03-01
The steady-state and time-resolved fluorescence characteristics of protochlorophyll (Pchl) dissolved in neat Triton X-100 and in Triton X-100 micelles were investigated, and the fluorescence lifetimes of different Pchl spectral forms were studied. Varying the concentration of Pchl or diluting the micellar solutions either with a buffer or with a micellar solution, 631-634, 645-655, 680-692 and above 700 nm emitting Pchl complexes were prepared, the ratios of which varied from one another. The fluorescence decay of the 631-634 nm emitting (monomeric) form had a mono-exponential character with a 5.4-ns fluorescence lifetime. The long-wavelength Pchl complexes (aggregates) had two fluorescence lifetime values within a range of 1.4-3.9 ns and 0.15-0.84 ns, which showed high variability in different environments. Depending on the conditions, either mono- or double-exponential fluorescence decay was found for a fluorescence band at 680-685 nm. These data show that despite their very similar steady-state fluorescence properties, Pchl complexes can differ in fluorescence lifetimes, which may reflect different molecular structures, intrinsic geometries or different molecular interactions. This underlines the importance of complex spectroscopic analysis for a precise description of native and artificial chlorophyllous pigment forms.
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Heat generation and light scattering of green fluorescent protein-like pigments in coral tissue
NASA Astrophysics Data System (ADS)
Lyndby, Niclas H.; Kühl, Michael; Wangpraseurt, Daniel
2016-05-01
Green fluorescent protein (GFP)-like pigments have been proposed to have beneficial effects on coral photobiology. Here, we investigated the relationships between green fluorescence, coral heating and tissue optics for the massive coral Dipsastraea sp. (previously Favia sp.). We used microsensors to measure tissue scalar irradiance and temperature along with hyperspectral imaging and combined imaging of variable chlorophyll fluorescence and green fluorescence. Green fluorescence correlated positively with coral heating and scalar irradiance enhancement at the tissue surface. Coral tissue heating saturated for maximal levels of green fluorescence. The action spectrum of coral surface heating revealed that heating was highest under red (peaking at 680 nm) irradiance. Scalar irradiance enhancement in coral tissue was highest when illuminated with blue light, but up to 62% (for the case of highest green fluorescence) of this photon enhancement was due to green fluorescence emission. We suggest that GFP-like pigments scatter the incident radiation, which enhances light absorption and heating of the coral. However, heating saturates, because intense light scattering reduces the vertical penetration depth through the tissue eventually leading to reduced light absorption at high fluorescent pigment density. We conclude that fluorescent pigments can have a central role in modulating coral light absorption and heating.
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Patil, Jagadish S; Anil, Arga Chandrashekar
2018-05-30
The variable fluorescence fluorometry measuring microalgal biomass (initial fluorescence - F 0 , a chl-a proxy) and photosynthetic efficiency (F v /F m ) has been suggested as a potential tool in ballast-water assessment. In ballast tank, microalgae can be found in contiguous compartments i.e., in water, sediment, and biofilms. Therefore the utility of F 0 and F v /F m depends upon proper background corrections, which is straightforward for water samples but not for sediment and biofilms. This study proposes procedures for correcting F 0 values from sediment and biofilms. Irrespective of the saturation flash protocol used on any sample types the outcome of the results from viable and non-viable microalgae will remain same. Stress experiments (continuous darkness and biocide treatments) confirm that variable fluorescence (F v ) can be used as a potential proxy for viable cells as the values were negligible for non-viable cells and increased with an increase in abundance. Through this study, the utility of F v and σ PSII (functional-absorption-cross-section of photosystem II) along with F 0 and F v /F m in providing additional information on cell-viability and algal-size group during assessment is discussed. The findings will have implications not only from the perspective of ballast water but also in testing/assays of specific interest (e.g. toxicity, water treatments, antifouling) and ecological studies involving microalgae. Copyright © 2018 Elsevier Ltd. All rights reserved.
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Murakoshi, Hideji; Shibata, Akihiro C E; Nakahata, Yoshihisa; Nabekura, Junichi
2015-10-15
Measurement of Förster resonance energy transfer by fluorescence lifetime imaging microscopy (FLIM-FRET) is a powerful method for visualization of intracellular signaling activities such as protein-protein interactions and conformational changes of proteins. Here, we developed a dark green fluorescent protein (ShadowG) that can serve as an acceptor for FLIM-FRET. ShadowG is spectrally similar to monomeric enhanced green fluorescent protein (mEGFP) and has a 120-fold smaller quantum yield. When FRET from mEGFP to ShadowG was measured using an mEGFP-ShadowG tandem construct with 2-photon FLIM-FRET, we observed a strong FRET signal with low cell-to-cell variability. Furthermore, ShadowG was applied to a single-molecule FRET sensor to monitor a conformational change of CaMKII and of the light oxygen voltage (LOV) domain in HeLa cells. These sensors showed reduced cell-to-cell variability of both the basal fluorescence lifetime and response signal. In contrast to mCherry- or dark-YFP-based sensors, our sensor allowed for precise measurement of individual cell responses. When ShadowG was applied to a separate-type Ras FRET sensor, it showed a greater response signal than did the mCherry-based sensor. Furthermore, Ras activation and translocation of its effector ERK2 into the nucleus could be observed simultaneously. Thus, ShadowG is a promising FLIM-FRET acceptor.
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Insights on the Optical Properties of Estuarine DOM - Hydrological and Biological Influences.
Santos, Luísa; Pinto, António; Filipe, Olga; Cunha, Ângela; Santos, Eduarda B H; Almeida, Adelaide
2016-01-01
Dissolved organic matter (DOM) in estuaries derives from a diverse array of both allochthonous and autochthonous sources. In the estuarine system Ria de Aveiro (Portugal), the seasonality and the sources of the fraction of DOM that absorbs light (CDOM) were inferred using its optical and fluorescence properties. CDOM parameters known to be affected by aromaticity and molecular weight were correlated with physical, chemical and meteorological parameters. Two sites, representative of the marine and brackish water zones of the estuary, and with different hydrological characteristics, were regularly surveyed along two years, in order to determine the major influences on CDOM properties. Terrestrial-derived compounds are the predominant source of CDOM in the estuary during almost all the year and the two estuarine zones presented distinct amounts, as well as absorbance and fluorescence characteristics. Freshwater inputs have major influence on the dynamics of CDOM in the estuary, in particular at the brackish water zone, where accounted for approximately 60% of CDOM variability. With a lower magnitude, the biological productivity also impacted the optical properties of CDOM, explaining about 15% of its variability. Therefore, climate changes related to seasonal and inter-annual variations of the precipitation amounts might impact the dynamics of CDOM significantly, influencing its photochemistry and the microbiological activities in estuarine systems.
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Insights on the Optical Properties of Estuarine DOM – Hydrological and Biological Influences
Santos, Luísa; Pinto, António; Filipe, Olga; Cunha, Ângela; Santos, Eduarda B. H.
2016-01-01
Dissolved organic matter (DOM) in estuaries derives from a diverse array of both allochthonous and autochthonous sources. In the estuarine system Ria de Aveiro (Portugal), the seasonality and the sources of the fraction of DOM that absorbs light (CDOM) were inferred using its optical and fluorescence properties. CDOM parameters known to be affected by aromaticity and molecular weight were correlated with physical, chemical and meteorological parameters. Two sites, representative of the marine and brackish water zones of the estuary, and with different hydrological characteristics, were regularly surveyed along two years, in order to determine the major influences on CDOM properties. Terrestrial-derived compounds are the predominant source of CDOM in the estuary during almost all the year and the two estuarine zones presented distinct amounts, as well as absorbance and fluorescence characteristics. Freshwater inputs have major influence on the dynamics of CDOM in the estuary, in particular at the brackish water zone, where accounted for approximately 60% of CDOM variability. With a lower magnitude, the biological productivity also impacted the optical properties of CDOM, explaining about 15% of its variability. Therefore, climate changes related to seasonal and inter-annual variations of the precipitation amounts might impact the dynamics of CDOM significantly, influencing its photochemistry and the microbiological activities in estuarine systems. PMID:27195702
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Red and Green Fluorescence from Oral Biofilms
Hoogenkamp, Michel A.; Krom, Bastiaan P.; Janus, Marleen M.; ten Cate, Jacob M.; de Soet, Johannes J.; Crielaard, Wim; van der Veen, Monique H.
2016-01-01
Red and green autofluorescence have been observed from dental plaque after excitation by blue light. It has been suggested that this red fluorescence is related to caries and the cariogenic potential of dental plaque. Recently, it was suggested that red fluorescence may be related to gingivitis. Little is known about green fluorescence from biofilms. Therefore, we assessed the dynamics of red and green fluorescence in real-time during biofilm formation. In addition, the fluorescence patterns of biofilm formed from saliva of eight different donors are described under simulated gingivitis and caries conditions. Biofilm formation was analysed for 12 hours under flow conditions in a microfluidic BioFlux flow system with high performance microscopy using a camera to allow live cell imaging. For fluorescence images dedicated excitation and emission filters were used. Both green and red fluorescence were linearly related with the total biomass of the biofilms. All biofilms displayed to some extent green and red fluorescence, with higher red and green fluorescence intensities from biofilms grown in the presence of serum (gingivitis simulation) as compared to the sucrose grown biofilms (cariogenic simulation). Remarkably, cocci with long chain lengths, presumably streptococci, were observed in the biofilms. Green and red fluorescence were not found homogeneously distributed within the biofilms: highly fluorescent spots (both green and red) were visible throughout the biomass. An increase in red fluorescence from the in vitro biofilms appeared to be related to the clinical inflammatory response of the respective saliva donors, which was previously assessed during an in vivo period of performing no-oral hygiene. The BioFlux model proved to be a reliable model to assess biofilm fluorescence. With this model, a prediction can be made whether a patient will be prone to the development of gingivitis or caries. PMID:27997567
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Red and Green Fluorescence from Oral Biofilms.
Volgenant, Catherine M C; Hoogenkamp, Michel A; Krom, Bastiaan P; Janus, Marleen M; Ten Cate, Jacob M; de Soet, Johannes J; Crielaard, Wim; van der Veen, Monique H
2016-01-01
Red and green autofluorescence have been observed from dental plaque after excitation by blue light. It has been suggested that this red fluorescence is related to caries and the cariogenic potential of dental plaque. Recently, it was suggested that red fluorescence may be related to gingivitis. Little is known about green fluorescence from biofilms. Therefore, we assessed the dynamics of red and green fluorescence in real-time during biofilm formation. In addition, the fluorescence patterns of biofilm formed from saliva of eight different donors are described under simulated gingivitis and caries conditions. Biofilm formation was analysed for 12 hours under flow conditions in a microfluidic BioFlux flow system with high performance microscopy using a camera to allow live cell imaging. For fluorescence images dedicated excitation and emission filters were used. Both green and red fluorescence were linearly related with the total biomass of the biofilms. All biofilms displayed to some extent green and red fluorescence, with higher red and green fluorescence intensities from biofilms grown in the presence of serum (gingivitis simulation) as compared to the sucrose grown biofilms (cariogenic simulation). Remarkably, cocci with long chain lengths, presumably streptococci, were observed in the biofilms. Green and red fluorescence were not found homogeneously distributed within the biofilms: highly fluorescent spots (both green and red) were visible throughout the biomass. An increase in red fluorescence from the in vitro biofilms appeared to be related to the clinical inflammatory response of the respective saliva donors, which was previously assessed during an in vivo period of performing no-oral hygiene. The BioFlux model proved to be a reliable model to assess biofilm fluorescence. With this model, a prediction can be made whether a patient will be prone to the development of gingivitis or caries.
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Wang, Ying; Zhang, Di; Shen, Zhenyao; Feng, Chenghong; Chen, Jing
2013-01-01
Dissolved organic matter (DOM) in sediment pore waters from Yangtze estuary of China based on abundance, UV absorbance, molecular weight distribution and fluorescence were investigated using a combination of various parameters of DOM as well as 3D fluorescence excitation emission matrix spectra (F-EEMS) with the parallel factor and principal component analysis (PARAFAC-PCA). The results indicated that DOM in pore water of Yangtze estuary was very variable which mainly composed of low aromaticity and molecular weight materials. Three humic-like substances (C1, C2, C4) and one protein-like substance (C3) were identified by PARAFAC model. C1, C2 and C4 exhibited same trends and were very similar. The separation of samples on both axes of the PCA showed the difference in DOM properties. C1, C2 and C4 concurrently showed higher positive factor 1 loadings, while C3 showed highly positive factor 2 loadings. The PCA analysis showed a combination contribution of microbial DOM signal and terrestrial DOM signal in the Yangtze estuary. Higher and more variable DOM abundance, aromaticity and molecular weight of surface sediment pore water DOM can be found in the southern nearshore than the other regions primarily due to the influence of frequent and intensive human activities and tributaries inflow in this area. The DOM abundance, aromaticity, molecular weight and fluorescence intensity in core of different depth were relative constant and increased gradually with depth. DOM in core was mainly composed of humic-like material, which was due to higher release of the sedimentary organic material into the porewater during early diagenesis. PMID:24155904
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Anschel, D.
1994-05-06
Levels of atmospheric carbon dioxide have been increasing at an unprecedented rate in modern times. In response to this situation, we have initiated a long-term study of a forest species` response to elevated carbon dioxide levels. We have set up a facility for subjecting P. ponderosa to ambient, ambient + 175 {mu}1 1{sup {minus}1}, and ambient + 350 {mu}1 1{sup {minus}1} CO{sub 2}. This report specifically concentrates on the effects of elevated CO{sub 2} on the photosynthetic system, as indicated by chlorophyll fluorescence and pigment assays. We tested for intraspecific variability by selecting nine different families of trees from fivemore » different geographic areas of California. There are differential responses to carbon dioxide treatments which appear to be dependent upon the tree`s genotype, as indicated by the relative efficiencies of photochemical electron flow in photosystem II (Fv/Fm). During the same testing period Fv/Fm varied by as much as 21.1% relative to ambient in the treated groups. Total chlorophyll, chlorophyll {alpha} and carotenoid values all showed statistically significant (p<0.05) drops in the treatment groups regardless of genotype. Chlorophyll {alpha} at one time showed the most dramatic drop of 3 mg/m2 in the + 350 {mu}1 1{sup {minus}1} CO{sub 2} group versus the ambient. Findings for both photosynthetic pigments and chlorophyll fluorescence vary somewhat over the course of several months.« less
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Duarte, José M; Barbier, Içvara; Schaerli, Yolanda
2017-11-17
Synthetic biologists increasingly rely on directed evolution to optimize engineered biological systems. Applying an appropriate screening or selection method for identifying the potentially rare library members with the desired properties is a crucial step for success in these experiments. Special challenges include substantial cell-to-cell variability and the requirement to check multiple states (e.g., being ON or OFF depending on the input). Here, we present a high-throughput screening method that addresses these challenges. First, we encapsulate single bacteria into microfluidic agarose gel beads. After incubation, they harbor monoclonal bacterial microcolonies (e.g., expressing a synthetic construct) and can be sorted according their fluorescence by fluorescence activated cell sorting (FACS). We determine enrichment rates and demonstrate that we can measure the average fluorescent signals of microcolonies containing phenotypically heterogeneous cells, obviating the problem of cell-to-cell variability. Finally, we apply this method to sort a pBAD promoter library at ON and OFF states.
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Estimating weak ratiometric signals in imaging data. I. Dual-channel data.
Broder, Josef; Majumder, Anirban; Porter, Erika; Srinivasamoorthy, Ganesh; Keith, Charles; Lauderdale, James; Sornborger, Andrew
2007-09-01
Ratiometric fluorescent indicators are becoming increasingly prevalent in many areas of biology. They are used for making quantitative measurements of intracellular free calcium both in vitro and in vivo, as well as measuring membrane potentials, pH, and other important physiological variables of interest to researchers in many subfields. Often, functional changes in the fluorescent yield of ratiometric indicators are small, and the signal-to-noise ratio (SNR) is of order unity or less. In particular, variability in the denominator of the ratio can lead to very poor ratio estimates. We present a statistical optimization method for objectively detecting and estimating ratiometric signals in dual-wavelength measurements of fluorescent, ratiometric indicators that improves on standard methods. With the use of an appropriate statistical model for ratiometric signals and by taking the pixel-pixel covariance of an imaging dataset into account, we are able to extract user-independent spatiotemporal information that retains high resolution in both space and time.
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Processes Affecting Variability of Fluorescence Signals from Benthic Targets in Shallow Waters
1997-09-30
processes in the Department of Chemistry at Brookhaven National Laboratory. The model organisms used are primarily cultured zooxanthellae obtained from...and closed (Fm) photosystem II reaction centers in the zooxanthellae isolated from the fire coral, Montipora. The short lifetime curve corresponds...individual zooxanthellae strains, is highly correlated Figure 2. The correlation between the average fluorescence lifetimes, calculated from a four
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Wiesmann, Veit; Bergler, Matthias; Palmisano, Ralf; Prinzen, Martin; Franz, Daniela; Wittenberg, Thomas
2017-03-18
Manual assessment and evaluation of fluorescent micrograph cell experiments is time-consuming and tedious. Automated segmentation pipelines can ensure efficient and reproducible evaluation and analysis with constant high quality for all images of an experiment. Such cell segmentation approaches are usually validated and rated in comparison to manually annotated micrographs. Nevertheless, manual annotations are prone to errors and display inter- and intra-observer variability which influence the validation results of automated cell segmentation pipelines. We present a new approach to simulate fluorescent cell micrographs that provides an objective ground truth for the validation of cell segmentation methods. The cell simulation was evaluated twofold: (1) An expert observer study shows that the proposed approach generates realistic fluorescent cell micrograph simulations. (2) An automated segmentation pipeline on the simulated fluorescent cell micrographs reproduces segmentation performances of that pipeline on real fluorescent cell micrographs. The proposed simulation approach produces realistic fluorescent cell micrographs with corresponding ground truth. The simulated data is suited to evaluate image segmentation pipelines more efficiently and reproducibly than it is possible on manually annotated real micrographs.
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LCLS in—photon out: fluorescence measurement of neon using soft x-rays
Obaid, Razib; Buth, Christian; Dakovski, Georgi L.; ...
2018-01-09
Here, we measured the fluorescence photon yield of neon upon soft x-ray ionization (~1200 eV) from the x-ray free-electron laser at Linac Coherent Light Source, and demonstrated the usage of a grazing incidence spectrometer with a variable line spacing grating to perform x-ray fluorescence spectroscopy on a gas phase system. Our measurements also allowed us to estimate the focal size of the beam from the theoretical description developed, in terms of the rate equation approximation accounting for photoionization shake off of neutral neon and double auger decay of single core holes.
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LCLS in—photon out: fluorescence measurement of neon using soft x-rays
NASA Astrophysics Data System (ADS)
Obaid, Razib; Buth, Christian; Dakovski, Georgi L.; Beerwerth, Randolf; Holmes, Michael; Aldrich, Jeff; Lin, Ming-Fu; Minitti, Michael; Osipov, Timur; Schlotter, William; Cederbaum, Lorenz S.; Fritzsche, Stephan; Berrah, Nora
2018-02-01
We measured the fluorescence photon yield of neon upon soft x-ray ionization (∼1200 eV) from the x-ray free-electron laser at Linac Coherent Light Source, and demonstrated the usage of a grazing incidence spectrometer with a variable line spacing grating to perform x-ray fluorescence spectroscopy on a gas phase system. Our measurements also allowed us to estimate the focal size of the beam from the theoretical description developed, in terms of the rate equation approximation accounting for photoionization shake off of neutral neon and double auger decay of single core holes.
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NASA Astrophysics Data System (ADS)
Zhou, Hongfu; Gang, Yadong; Chen, Shenghua; Wang, Yu; Xiong, Yumiao; Li, Longhui; Yin, Fangfang; Liu, Yue; Liu, Xiuli; Zeng, Shaoqun
2017-10-01
Plastic embedding is widely applied in light microscopy analyses. Previous studies have shown that embedding agents and related techniques can greatly affect the quality of biological tissue embedding and fluorescent imaging. Specifically, it is difficult to preserve endogenous fluorescence using currently available acidic commercial embedding resins and related embedding techniques directly. Here, we developed a neutral embedding resin that improved the green fluorescent protein (GFP), yellow fluorescent protein (YFP), and DsRed fluorescent intensity without adjusting the pH value of monomers or reactivating fluorescence in lye. The embedding resin had a high degree of polymerization, and its fluorescence preservation ratios for GFP, YFP, and DsRed were 126.5%, 155.8%, and 218.4%, respectively.
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Red fluorescent biofilm: the thick, the old, and the cariogenic
Volgenant, Catherine M.C.; Hoogenkamp, Michel A.; Buijs, Mark J.; Zaura, Egija; ten Cate, Jacob (Bob) M.; van der Veen, Monique H.
2016-01-01
Background Some dental plaque fluoresces red. The factors involved in this fluorescence are yet unknown. Objective The aim of this study was to assess systematically the effect of age, thickness, and cariogenicity on the extent of red fluorescence produced by in vitro microcosm biofilms. Design The effects of biofilm age and thickness on red fluorescence were tested in a constant depth film fermentor (CDFF) by growing biofilms of variable thicknesses that received a constant supply of defined mucin medium (DMM) and eight pulses of sucrose/day. The influence of cariogenicity on red fluorescence was tested by growing biofilm on dentin disks receiving DMM, supplemented with three or eight pulses of sucrose/day. The biofilms were analyzed at different time points after inoculation, up to 24 days. Emission spectra were measured using a fluorescence spectrophotometer (λexc405 nm) and the biofilms were photographed with a fluorescence camera. The composition of the biofilms was assessed using 454-pyrosequecing of the 16S rDNA gene. Results From day 7 onward, the biofilms emitted increasing intensities of red fluorescence as evidenced by the combined red fluorescence peaks. The red fluorescence intensity correlated with biofilm thickness but not in a linear way. Biofilm fluorescence also correlated with the imposed cariogenicity, evidenced by the induced dentin mineral loss. Increasing the biofilm age or increasing the sucrose pulsing frequency led to a shift in the microbial composition. These shifts in composition were accompanied by an increase in red fluorescence. Conclusions The current study shows that a thicker, older, or more cariogenic biofilm results in a higher intensity of red fluorescence. PMID:27060056
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Fluorescent pH sensor based on Ag@SiO2 core-shell nanoparticle.
Bai, Zhenhua; Chen, Rui; Si, Peng; Huang, Youju; Sun, Handong; Kim, Dong-Hwan
2013-06-26
We have demonstrated a novel method for the preparation of a fluorescence-based pH sensor by combining the plasmon resonance band of Ag core and pH sensitive dye (HPTS). A thickness-variable silica shell is placed between Ag core and HPTS dye to achieve the maximum fluorescence enhancement. At the shell thickness of 8 nm, the fluorescence intensity increases 4 and 9 times when the sensor is excited at 405 and 455 nm, respectively. At the same time, the fluorescence intensity shows a good sensitivity toward pH value in the range of 5-9, and the ratio of emission intensity at 513 nm excited at 455 nm to that excited at 405 nm versus the pH value in the range of 5-9 is determined. It is believed that the present pH sensor has the potential for determining pH real time in the biological sample.
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Segmentation and classification of cell cycle phases in fluorescence imaging.
Ersoy, Ilker; Bunyak, Filiz; Chagin, Vadim; Cardoso, M Christina; Palaniappan, Kannappan
2009-01-01
Current chemical biology methods for studying spatiotemporal correlation between biochemical networks and cell cycle phase progression in live-cells typically use fluorescence-based imaging of fusion proteins. Stable cell lines expressing fluorescently tagged protein GFP-PCNA produce rich, dynamically varying sub-cellular foci patterns characterizing the cell cycle phases, including the progress during the S-phase. Variable fluorescence patterns, drastic changes in SNR, shape and position changes and abundance of touching cells require sophisticated algorithms for reliable automatic segmentation and cell cycle classification. We extend the recently proposed graph partitioning active contours (GPAC) for fluorescence-based nucleus segmentation using regional density functions and dramatically improve its efficiency, making it scalable for high content microscopy imaging. We utilize surface shape properties of GFP-PCNA intensity field to obtain descriptors of foci patterns and perform automated cell cycle phase classification, and give quantitative performance by comparing our results to manually labeled data.
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Analysis and Modeling of Chromosome Congression During Mitosis in the Chemotherapy Drug Cisplatin.
Chacón, Jeremy M; Gardner, Melissa K
2013-12-01
The chemotherapy drug Cisplatin (cis-diamminedichloroplatinum(II)) induces crosslinks within and between DNA strands, and between DNA and nearby proteins. Therefore, Cisplatin-treated cells which progress into cell division may do so with altered chromosome mechanical properties. This could have important consequences for the successful completion of mitosis. Using Total Internal Reflection Fluorescence (TIRF) microscopy of live Cisplatin-treated Saccharomyces cerevisiae cells, we found that metaphase mitotic spindles have disorganized kinetochores relative to untreated cells, and also that there is increased variability in the chromosome stretching distance between sister centromeres. This suggests that chromosome stiffness may become more variable after Cisplatin treatment. We explored the effect of variable chromosome stiffness during mitosis using a stochastic model in which kinetochore microtubule dynamics were regulated by tension imparted by stretched sister chromosomes. Consistent with experimental results, increased variability of chromosome stiffness in the model led to disorganization of kinetochores in simulated metaphase mitotic spindles. Furthermore, the variability in simulated chromosome stretching tension was increased as chromosome stiffness became more variable. Because proper chromosome stretching tension may serve as a signal that is required for proper progression through mitosis, tension variability could act to impair this signal and thus prevent proper mitotic progression. Our results suggest a possible mitotic mode of action for the anti-cancer drug Cisplatin.
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Deep Space Gateway Ecosystem Observatory
NASA Astrophysics Data System (ADS)
Huemmrich, K. F.; Campbell, P. E.; Middleton, E. M.
2018-02-01
Advance global understanding of seasonal change and diurnal variability of terrestrial ecosystem function, photosynthesis, and stress responses using spectral reflectance, thermal, and fluorescence signals.
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Free volume dependent fluorescence property of PMMA composite: Positron annihilation studies
NASA Astrophysics Data System (ADS)
Ravindrachary, V.; Praveena, S. D.; Bhajantri, R. F.; Ismayil, Crasta, Vincent
2013-02-01
The free volume related fluorescence properties of chalcone chromophore [1-(4-methylphenyl)-3-(4-N, N, dimethylaminophenyl)-2-propen-1-one doped Poly(methyl methacrylate) have been studied using fluorescence spectroscopy and Positron Annihilation lifetime spectroscopy techniques. The fluorescence spectra show that the fluorescence behavior depends on the free volume dependent polymer microstructure and varies with dopant concentration with in the composite. The origin and variation of fluorescence is understood by twisted internal charge transfer state as well as free volume. The Positron annihilation study shows that the free volume related microstructure of the composite is vary with doping level.
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NASA Astrophysics Data System (ADS)
Healy, D. A.; Huffman, J. A.; O'Connor, D. J.; Pöhlker, C.; Pöschl, U.; Sodeau, J. R.
2014-02-01
Primary biological aerosol particles (PBAP) can contribute significantly to the coarse particle burden in many environments, may thus influence climate and precipitation systems as cloud nuclei, and can spread disease to humans, animals, and plants. Measurements of PBAP in natural environments taken at high time- and size- resolution are, however, sparse and so large uncertainties remain in the role that biological particles play in the Earth system. In this study two commercial real-time fluorescence particle sensors and a Sporewatch single-stage particle impactor were operated continuously from 2 August to 2 September 2010 at a rural sampling location in Killarney National Park in south western Ireland. A cascade impactor was operated periodically to collect size-resolved particles during exemplary periods. Here we report the first ambient comparison of the waveband integrated bioaerosol sensor (WIBS-4) with the ultraviolet aerodynamic particle sizer (UV-APS) and also compare these real-time fluorescence techniques with results of fluorescence and optical microscopy of impacted samples. Both real-time instruments showed qualitatively similar behaviour, with increased fluorescent bioparticle concentrations at night when relative humidity was highest and temperature was lowest. The fluorescent particle number from the FL3 channel of the WIBS-4 and from the UV-APS were strongly correlated and dominated by a 3 μm mode in the particle size distribution. The WIBS FL2 channel exhibited particle modes at approx. 1 and 3 μm, and each were correlated with the concentration of fungal spores commonly observed in air samples collected at the site (ascospores, basidiospores, Ganoderma spp.). The WIBS FL1 channel exhibited variable multi-modal distributions turning into a broad featureless single mode after averaging and exhibited poor correlation with fungal spore concentrations, which may be due to the detection of bacterial and non-biological fluorescent particles. Cladosporium spp., which are among the most abundant fungal spores in many terrestrial environments, were not correlated with any of the real-time fluorescence channels, suggesting that the real-time fluorescence instruments are insensitive to PBAP classes with dark, highly absorptive cell walls. Fluorescence microscopy images of cascade impactor plates showed large numbers of coarse mode particles consistent with the morphology and weak fluorescence expected of sea salt. Some of these particles were attached to biological cells, suggesting that a marine source influenced the PBAP observed at the site and that the ocean may be an important contributor to PBAP loadings in coastal environments.
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NASA Astrophysics Data System (ADS)
Elahi, Sakib F.; Lee, Seung Y.; Lloyd, William R.; Chen, Leng-Chun; Kuo, Shiuhyang; Zhou, Ying; Kim, Hyungjin M.; Kennedy, Robert; Marcelo, Cynthia; Feinberg, Stephen E.; Mycek, Mary-Ann
2018-02-01
Clinical translation of engineered tissue constructs requires noninvasive methods to assess construct health and viability after implantation in patients. However, current practices to monitor post-implantation construct integration are either qualitative (visual assessment) or destructive (tissue histology). As label-free fluorescence lifetime sensing can noninvasively characterize pre-implantation construct viability, we employed a handheld fluorescence lifetime spectroscopy probe to quantitatively and noninvasively assess tissue constructs that were implanted in a murine model. We designed the system to be suitable for intravital measurements: portability, localization with precise maneuverability, and rapid data acquisition. Our model tissue constructs were manufactured from primary human cells to simulate patient variability and were stressed to create a range of health states. Secreted amounts of three cytokines that relate to cellular viability were measured in vitro to assess pre-implantation construct health. In vivo optical sensing assessed tissue integration of constructs at one-week and three-weeks post-implantation. At one-week post-implantation, optical parameters correlated with in vitro pre-implantation secretion levels of all three cytokines (p < 0.05). This relationship was no longer seen at three-weeks post-implantation, suggesting comparable tissue integration independent of preimplantation health. Histology confirmed re-epithelialization of these constructs independent of pre-implantation health state, supporting the lack of a correlation. These results suggest that clinical optical diagnostic tools based on label-free fluorescence lifetime sensing of endogenous tissue fluorophores could noninvasively monitor post-implantation integration of engineered tissues.
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Yim, Sung Sun; Bang, Hyun Bae; Kim, Young Hwan; Lee, Yong Jae; Jeong, Gu Min; Jeong, Ki Jun
2014-01-01
Antibodies and their derivatives are the most important agents in therapeutics and diagnostics. Even after the significant progress in the technology for antibody screening from huge libraries, it takes a long time to isolate an antibody, which prevents a prompt action against the spread of a disease. Here, we report a new strategy for isolating desired antibodies from a combinatorial library in one day by repeated fluorescence-activated cell sorting (FACS). First, we constructed a library of synthetic human antibody in which single-chain variable fragment (scFv) was expressed in the periplasm of Escherichia coli. After labeling the cells with fluorescent antigen probes, the highly fluorescent cells were sorted by using a high-speed cell sorter, and these cells were reused without regeneration in the next round of sorting. After repeating this sorting, the positive clones were completely enriched in several hours. Thus, we screened the library against three viral antigens, including the H1N1 influenza virus, Hepatitis B virus, and Foot-and-mouth disease virus. Finally, the potential antibody candidates, which show KD values between 10 and 100 nM against the target antigens, could be successfully isolated even though the library was relatively small (∼106). These results show that repeated FACS screening without regeneration of the sorted cells can be a powerful method when a rapid response to a spreading disease is required. PMID:25303314
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Major, John E; Barsi, Debby C; Mosseler, Alex; Campbell, Moira; Rajora, Om P
2003-07-01
Red spruce (Picea rubens Sarg.) and black spruce (Picea mariana (Mill.) B.S.P.) are genetically and morphologically similar but ecologically distinct species. We determined intraspecific seed-source and interspecific variation of red spruce and black spruce, from across the near-northern margins of their ranges, for several light-energy processing and freezing-tolerance adaptive traits. Before exposure to low temperature, red spruce had variable fluorescence (Fv) similar to black spruce, but higher photochemical efficiency (Fv/Fm), lower quantum yield, lower chlorophyll fluorescence (%), and higher thermal dissipation efficiency (qN), although the seed-source effect and the seed-source x species interaction were significant only for Fv/Fm. After low-temperature exposure (-40 degrees C), red spruce had significantly lower Fv/Fm, quantum yield and qN than black spruce, but higher chlorophyll fluorescence and relative fluorescence. Species, seed-source effect, and seed-source x species interaction were consistent with predictions based on genetic (e.g., geographic) origins. Multi-temperature exposures (5, -20 and -40 degrees C) often produced significant species and temperature effects, and species x temperature interactions as a result of species-specific responses to temperature exposures. The inherent physiological species-specific adaptations of red spruce and black spruce were largely consistent with a shade-tolerant, late-successional species and an early successional species, respectively. Species differences in physiological adaptations conform to a biological trade-off, probably as a result of natural selection pressure in response to light availability and prevailing temperature gradients.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Carvalho, M.L.; Amorim, P.; Marques, M.I.M.
1997-04-01
Fucus vesiculosus L. seaweeds from three estuarine stations were analyzed by X-ray fluorescence, providing results for the concentration of total K, Ca, Ti, Mn, Fe, Co, Ni, Cu, Zn, As, Br, Sr, and Pb. Four different structures of the algae (base, stipe, reproductive organs, and growing tips) were analyzed to study the differential accumulation of heavy metals by different parts of Fucus. Some elements (e.g., Cu and Fe) are preferentially accumulated in the base of the algae, whereas others (e.g., As) exhibit higher concentrations in the reproductive organs and growing tips. The pattern of accumulation in different structures is similarmore » for Cu, Zn, and Pb, but for other metals there is considerable variability in accumulation between parts of the plant. This is important in determining which structures of the plant should be used for biomonitoring. For samples collected at stations subject to differing metal loads, the relative elemental composition is approximately constant, notwithstanding significant variation in absolute values. The proportion of metals in Fucus is similar to that found in other estuaries, where metal concentrations are significantly lower. Energy-dispersive X-ray fluorescence has been shown to be a suitable technique for multielement analysis in this type of sample. No chemical pretreatment is required, minimizing sample contamination. The small amount of sample required, and the wide range of elements that can be detected simultaneously make energy-dispersive X-ray fluorescence a valuable tool for pollution studies.« less
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Ghosh, Sreya; Preza, Chrysanthe
2015-07-01
A three-dimensional (3-D) point spread function (PSF) model for wide-field fluorescence microscopy, suitable for imaging samples with variable refractive index (RI) in multilayered media, is presented. This PSF model is a key component for accurate 3-D image restoration of thick biological samples, such as lung tissue. Microscope- and specimen-derived parameters are combined with a rigorous vectorial formulation to obtain a new PSF model that accounts for additional aberrations due to specimen RI variability. Experimental evaluation and verification of the PSF model was accomplished using images from 175-nm fluorescent beads in a controlled test sample. Fundamental experimental validation of the advantage of using improved PSFs in depth-variant restoration was accomplished by restoring experimental data from beads (6 μm in diameter) mounted in a sample with RI variation. In the investigated study, improvement in restoration accuracy in the range of 18 to 35% was observed when PSFs from the proposed model were used over restoration using PSFs from an existing model. The new PSF model was further validated by showing that its prediction compares to an experimental PSF (determined from 175-nm beads located below a thick rat lung slice) with a 42% improved accuracy over the current PSF model prediction.
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Leclerc, L; Rima, W; Boudard, D; Pourchez, J; Forest, V; Bin, V; Mowat, P; Perriat, P; Tillement, O; Grosseau, P; Bernache-Assollant, D; Cottier, M
2012-08-01
Micrometric and nanometric particles are increasingly used in different fields and may exhibit variable toxicity levels depending on their physicochemical characteristics. The aim of this study was to determine the impact of the size parameter on cellular uptake and biological activity, working with well-characterized fluorescent particles. We focused our attention on macrophages, the main target cells of the respiratory system responsible for the phagocytosis of the particles. FITC fluorescent silica particles of variable submicronic sizes (850, 500, 250 and 150 nm) but with similar surface coating (COOH) were tailored and physico-chemically characterized. These particles were then incubated with the RAW 264.7 macrophage cell line. After microscopic observations (SEM, TEM, confocal), a quantitative evaluation of the uptake was carried out. Fluorescence detected after a quenching with trypan blue allows us to distinguish and quantify entirely engulfed fluorescent particles from those just adhering to the cell membrane. Finally, these data were compared to the in vitro toxicity assessed in terms of cell damage, inflammation and oxidative stress (evaluated by LDH release, TNF-α and ROS production respectively). Particles were well characterized (fluorescence, size distribution, zeta potential, agglomeration and surface groups) and easily visualized after cellular uptake using confocal and electron microscopy. The number of internalized particles was precisely evaluated. Size was found to be an important parameter regarding particles uptake and in vitro toxicity but this latter strongly depends on the particles doses employed.
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Hoffman, Robert A; Wang, Lili; Bigos, Martin; Nolan, John P
2012-09-01
Results from a standardization study cosponsored by the International Society for Advancement of Cytometry (ISAC) and the US National Institute of Standards and Technology (NIST) are reported. The study evaluated the variability of assigning intensity values to fluorophore standard beads by bead manufacturers and the variability of cross calibrating the standard beads to stained polymer beads (hard-dyed beads) using different flow cytometers. Hard dyed beads are generally not spectrally matched to the fluorophores used to stain cells, and spectral response varies among flow cytometers. Thus if hard dyed beads are used as fluorescence calibrators, one expects calibration for specific fluorophores (e.g., FITC or PE) to vary among different instruments. Using standard beads surface-stained with specific fluorophores (FITC, PE, APC, and Pacific Blue™), the study compared the measured intensity of fluorophore standard beads to that of hard dyed beads through cross calibration on 133 different flow cytometers. Using robust CV as a measure of variability, the variation of cross calibrated values was typically 20% or more for a particular hard dyed bead in a specific detection channel. The variation across different instrument models was often greater than the variation within a particular instrument model. As a separate part of the study, NIST and four bead manufacturers used a NIST supplied protocol and calibrated fluorophore solution standards to assign intensity values to the fluorophore beads. Values assigned to the reference beads by different groups varied by orders of magnitude in most cases, reflecting differences in instrumentation used to perform the calibration. The study concluded that the use of any spectrally unmatched hard dyed bead as a general fluorescence calibrator must be verified and characterized for every particular instrument model. Close interaction between bead manufacturers and NIST is recommended to have reliable and uniformly assigned fluorescence standard beads. Copyright © 2012 International Society for Advancement of Cytometry.
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Chair-side detection of Prevotella Intermedia in mature dental plaque by its fluorescence.
Nomura, Yoshiaki; Takeuchi, Hiroaki; Okamoto, Masaaki; Sogabe, Kaoru; Okada, Ayako; Hanada, Nobuhiro
2017-06-01
Prevotella intermedia/nigrescens is one of the well-known pathogens causing periodontal diseases, and the red florescence excited by the visible blue light caused by the protoporphyrin IX in the bacterial cells could be useful for the chair-side detection. The aim of this study was to evaluated levels of periodontal pathogen, especially P. intermedia in clinical samples of red fluorescent dental plaque. Thirty two supra gingival plaque samples from six individuals were measured its fluorescence at 640nm wavelength excited by 409nm. Periodontopathic bacteria were counted by the Invader PLUS PCR assay. Co-relations the fluorescence intensity and bacterial counts were analyzed by Person's correlation coefficient and simple and multiple regression analysis. Positive and negative predictive values of the fluorescence intensities for with or without P. intermedia in supragingival plaque was calculated. When relative fluorescence unit (RFU) were logarithmic transformed, statistically significant linear relations between RFU and bacterial counts were obtained for P. intermedia, Porphyromonas gingivalis and Tannerella forsythia. By the multiple regression analysis, only P. intermedia had statistically significant co-relation with fluorescence intensities. All of the fluorescent dental plaque contained P. intermedia m. In contrast, 28% of non-fluorescent plaques contained P. intermedia. To check the fluorescence dental plaque in the oral cavity could be the simple chair-side screening of the mature dental plaque before examining the periodontal pathogens especially P. intermedia by the PCR method. Copyright © 2017 Elsevier B.V. All rights reserved.
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Intrinsic fluorescence biomarkers in cells treated with chemopreventive drugs
NASA Astrophysics Data System (ADS)
Kirkpatrick, Nathaniel D.; Brands, William R.; Zou, Changping; Brewer, Molly A.; Utzinger, Urs
2005-03-01
Non-invasive monitoring of cellular metabolism offers promising insights into areas ranging from biomarkers for drug activity to cancer diagnosis. Fluorescence spectroscopy can be utilized in order to exploit endogenous fluorophores, typically metabolic co-factors nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD), and estimate the redox status of the sample. Fluorescence spectroscopy was applied to follow metabolic changes in epithelial ovarian cells as well as bladder epithelial cancer cells during treatment with a chemopreventive drug that initiates cellular quiescence. Fluorescence signals consistent with NADH, FAD, and tryptophan were measured to monitor cellular activity, redox status, and protein content. Cells were treated with varying concentrations of N-4-(hydroxyphenyl) retinamide (4-HPR) and measured in a stable environment with a sensitive fluorescence spectrometer. A subset of measurements was completed on a low concentration of cells to demonstrate feasibility for medical application such as in bladder or ovary washes. Results suggest that all of the cells responded with similar dose dependence but started at different estimated redox ratio baseline levels correlating with cell cycle, growth inhibition, and apoptosis assays. NADH and tryptophan related fluorescence changed significantly while FAD related fluorescence remained unaltered. Fluorescence data collected from approximately 1000 - 2000 cells, comparable to a bladder or ovary wash, was measurable and useful for future experiments. This study suggests that future intrinsic biomarker measurements may need to be most sensitive to changes in NADH and tryptophan related fluorescence while using FAD related fluorescence to help estimate the baseline redox ratio and predict response to chemopreventive agents.
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Nanosecond fluorescence microscopy. Emission kinetics of fura-2 in single cells.
Keating, S M; Wensel, T G
1991-01-01
A microscope based time-correlated single photon counting instrument has been constructed to measure fluorescence intensity and emission anisotropy decays from fluorophores in single cells on a nanosecond time scale. The sample is excited and the emission collected using epi-illumination optics with frequency-doubled pulses from the cavity-dumped output of a synchronously pumped dye laser serving as an excitation source. Collection of decays from a single cell is possible due to the presence of an iris in the emission path that can be reduced to less than the diameter of a single cell. Using the instrument the decay of 60 nM 1,6-diphenyl-1,3,5-hexatriene was measured, demonstrating that adequate data for lifetime analysis can be recorded from fewer 10(3) molecules of the fluorophore in an illuminated volume of 23 fl. In addition, the intensity and anisotropy decays of fura-2 in single adherent cells and in suspensions of fura-2 loaded cells in suspension, although the relative amplitudes and decay constants vary somewhat from cell to cell. The results indicate that a significant but variable fraction of fura-2 is bound to relatively immobile macromolecular components in these cells. PMID:2015383
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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.
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NASA Astrophysics Data System (ADS)
Chen, Muhua; Zheng, Yuhui; Gao, Jinwei; Wang, Qianming
2016-10-01
A new type of Eu(III)-gatifloxacin complex with characteristic red luminescence has been prepared. Due to the presence of ionization effect linked to the organic chromophore, the molecular fluorescent sensor demonstrated variable pH-sensitive absorption and emission curves. The red emission derived from europium ions was strong during pH range 8-10. Between pH = 7 and 4, the europium emission remained relatively stable and fluorescence signals of gatifloxacin has been improved substantially. Under acidic conditions (pH = 1 to 3), the dramatic changes in the emission colors (from red, yellow to green) were clearly observed. Moreover, the excitation wavelength can be extended into the visible light range (Ex = 411 nm) by using the concentration effect experiment. Importantly, it gave turn-off emissions in the presence of Cu2+ or Fe3+ and the detection limits were determined to be 6.5 μM for Cu2+ and 6.2 μM for Fe3+ respectively.
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Probing short-range protein Brownian motion in the cytoplasm of living cells
Di Rienzo, Carmine; Piazza, Vincenzo; Gratton, Enrico; Beltram, Fabio; Cardarelli, Francesco
2014-01-01
The translational motion of molecules in cells deviates from what is observed in dilute solutions. Theoretical models provide explanations for this effect but with predictions that drastically depend on the nanoscale organization assumed for macromolecular crowding agents. A conclusive test of the nature of the translational motion in cells is missing owing to the lack of techniques capable of probing crowding with the required temporal and spatial resolution. Here we show that fluorescence-fluctuation analysis of raster scans at variable timescales can provide this information. By using green fluorescent proteins in cells, we measure protein motion at the unprecedented timescale of 1 μs, unveiling unobstructed Brownian motion from 25 to 100 nm, and partially suppressed diffusion above 100 nm. Furthermore, experiments on model systems attribute this effect to the presence of relatively immobile structures rather than to diffusing crowding agents. We discuss the implications of these results for intracellular processes. PMID:25532887
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Indoor Light Performance of Coil Type Cylindrical Dye Sensitized Solar Cells.
Kapil, Gaurav; Ogomi, Yuhei; Pandey, Shyam S; Ma, Tingli; Hayase, Shuzi
2016-04-01
A very good performance under low/diffused light intensities is one of the application areas in which dye-sensitized solar cells (DSSCs) can be utilized effectively compared to their inorganic silicon solar cell counterparts. In this article, we have investigated the 1 SUN and low intensity fluorescent light performance of Titanium (Ti)-coil based cylindrical DSSC (C-DSSC) using ruthenium based N719 dye and organic dyes such as D205 and Y123. Electrochemical impedance spectroscopic results were analyzed for variable solar cell performances. Reflecting mirror with parabolic geometry as concentrator was also utilized to tap diffused light for indoor applications. Fluorescent light at relatively lower illumination intensities (0.2 mW/cm2 to 0.5 mW/cm2) were used for the investigation of TCO-less C-DSSC performance with and without reflector geometry. Furthermore, the DSSC performances were analyzed and compared with the commercially available amorphous silicon based solar cell for indoor applications.
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Flow cytometry of mammalian sperm: progress in DNA and morphology measurement.
Pinkel, D; Dean, P; Lake, S; Peters, D; Mendelsohn, M; Gray, J; Van Dilla, M; Gledhill, B
1979-01-01
Variability in DNA content and head shape of mammalian sperm are potentially useful markers for flow cytometric monitoring of genetic damage in spermatogenic cells. The high refractive index and extreme flatness of the sperm heads produce an optical effect which interferes with DNA measurements in flow cytometers which have dye excitation and fluorescence light collection normal to the axis of flow. Orientation of sperm in flow controls this effect and results in coefficients of variation of 2.5% and 4.2%, respectively, for DNA measurements of mouse and human sperm. Alternatively, the optical effect can be used to generate shape-related information. Measurements on randomly oriented sperm from three mammalian species using a pair of fluorescence detectors indicate that large shape differences are detectable. Acriflavine-Feulgen stained sperm nuclei are significantly bleached during flow cytometric measurements at power levels routinely used in many flow cytometers. Dual beam studies of this phenomenon indicate it may be useful in detecting abnormally shaped sperm.
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NASA Astrophysics Data System (ADS)
Merlier, Elodie; Hmimina, Gabriel; Dufrêne, Eric; Soudani, Kamel
2014-05-01
The Photochemical Reflectance Index (PRI) was designed as a proxy of the state of xanthophyll cycle which is used as a response of plants to excess of light (Gamon et al., 1990; 1992). Strong relationships between PRI and LUE were shown at leaf and canopy scales and over a wide range of species (Garbulsky et al., 2011). However, its use at canopy scale was shown to be significantly hampered by effects of confounding factors such as the PRI sensitivity to leaf pigment content (Gamon et al. 2001; Nakaji et al. 2006) and to canopy structure (Hilker et al. 2008). Several approaches aimed at correcting such effects and recent works focused on the deconvolution of LUE related and LUE unrelated PRI variability (Rahimzadeh-Bajgiran et al. 2012).In this study, the PRI variability at canopy scale is investigated over two years on three species (Fagus sylvatica, Quercus robur and Pinus sylvestris) growing under two water regimes. At daily scale, PRI variability is mainly explained by radiation conditions. As already reported at leaf scale in Hmimina et al. (2014), analysis of PRI responses to incoming photosynthetically active radiation over seasonal scale allowed to separate two sources of variability : a constitutive variability mainly related to canopy structure and leaf chlorophyll content and a facultative variability mainly related to LUE and soil moisture content. These results highlight the composite nature of PRI signal measured at canopy scale and the importance of disentangling its sources of variability in order to accurately assess ecosystem light use efficiency. Gamon JA, Field CB, Bilger W, Björkman O, Fredeen AL, Peñuelas J. 1990. Remote sensing of the xanthophyll cycle and chlorophyll fluorescence in sunflower leaves and canopies. Oecologia 85, 1-7. Gamon JA, Field CB, Fredeen A AL, Thayer S. 2001. Assessing photosynthetic downregulation in sunflower stands with an optically-based model. Photosynthesis Research 67, 113-125. Gamon JA, Peñuelas J, Field CB. 1992. A narrow-waveband spectral index that tracks diurnal changes in photosynthetic efficiency. Remote Sensing of Environment 41, 35-44. Garbulsky MF, Peñuelas J, Gamon J, Inoue Y, Filella I. 2011. The photochemical reflectance index (PRI) and the remote sensing of leaf, canopy and ecosystem radiation use efficiencies: A review and meta-analysis. Remote Sensing of Environment 115, 281-297. Hilker T, Coops NC, Hall FG, Black TA, Wulder MA, Nesic Z, Krishnan P. 2008. Separating physiologically and directionally induced changes in PRI using BRDF models. Remote Sensing of Environment 112, 2777-2788. Hmimina G, Dufrêne E, Soudani K. 2014. Relationship between PRI and leaf ecophysiological and biochemical parameters under two different water statuses: toward a rapid and efficient correction method using real-time measurements. Plant, Cell & Environment 37, 2, 473-487. Nakaji T, Oguma H, Fujinuma Y. 2006. Seasonal changes in the relationship between photochemical reflectance index and photosynthetic light use efficiency of Japanese larch needles. International Journal of Remote Sensing 27, 493-509. Rahimzadeh-Bajgiran P, Munehiro M, Omasa K. 2012. Relationships between the photochemical reflectance index (PRI) and chlorophyll fluorescence parameters and plant pigment indices at different leaf growth stages. Photosynthesis Research 113, 261-271.
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Sergeeva, Tatiana F; Shirmanova, Marina V; Zlobovskaya, Olga A; Gavrina, Alena I; Dudenkova, Varvara V; Lukina, Maria M; Lukyanov, Konstantin A; Zagaynova, Elena V
2017-03-01
A complex cascade of molecular events occurs in apoptotic cells but cell-to-cell variability significantly complicates determination of the order and interconnections between different processes. For better understanding of the mechanisms of programmed cell death, dynamic simultaneous registration of several parameters is required. In this paper we used multiparameter fluorescence microscopy to analyze energy metabolism, intracellular pH and caspase-3 activation in living cancer cells in vitro during staurosporine-induced apoptosis. We performed metabolic imaging of two co-factors, NAD(P)H and FAD, and used the genetically encoded pH-indicator SypHer1 and the FRET-based sensor for caspase-3 activity, mKate2-DEVD-iRFP, to visualize these parameters by confocal fluorescence microscopy and two-photon fluorescence lifetime imaging microscopy. The correlation between energy metabolism, intracellular pH and caspase-3 activation and their dynamic changes were studied in CT26 cancer cells during apoptosis. Induction of apoptosis was accompanied by a switch to oxidative phosphorylation, cytosol acidification and caspase-3 activation. We showed that alterations in cytosolic pH and the activation of oxidative phosphorylation are relatively early events associated with the induction of apoptosis. Copyright © 2017 Elsevier B.V. All rights reserved.
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Pan-arctic trends in terrestrial dissolved organic matter from optical measurements
Mann, Paul J.; Spencer, Robert G.M.; Hernes, Peter J.; Six, Johan; Aiken, George R.; Tank, Suzanne E.; McClelland, James W.; Butler, Kenna D.; Dyda, Rachael Y.; Holmes, Robert M.
2016-01-01
Climate change is causing extensive warming across Arctic regions resulting in permafrost degradation, alterations to regional hydrology and shifting amounts and composition of dissolved organic matter (DOM) transported by streams and rivers. Here, we characterize the DOM composition and optical properties of the six largest Arctic rivers draining into the Arctic Ocean to examine the ability of optical measurements to provide meaningful insights into terrigenous carbon export patterns and biogeochemical cycling. The chemical composition of aquatic DOM varied with season, spring months were typified by highest lignin phenol and dissolved organic carbon (DOC) concentrations with greater hydrophobic acid content, and lower proportions of hydrophilic compounds, relative to summer and winter months. Chromophoric DOM (CDOM) spectral slope (S275–295) tracked seasonal shifts in DOM composition across river basins. Fluorescence and parallel factor analysis identified seven components across the six Arctic rivers. The ratios of “terrestrial humic-like” vs. “marine humic-like” fluorescent components co-varied with lignin monomer ratios over summer and winter months, suggesting fluorescence may provide information on the age and degradation state of riverine DOM. CDOM absorbance (a350) proved a sensitive proxy for lignin phenol concentrations across all six river basins and over the hydrograph, enabling for the first time the development of a single pan-arctic relationship between a350 and terrigenous DOC (R2 = 0.93). Combining this lignin proxy with high-resolution monitoring of a350, pan-arctic estimates of annual lignin flux were calculated to range from 156 to 185 Gg, resulting in shorter and more constrained estimates of terrigenous DOM residence times in the Arctic Ocean (spanning 7 months to 2½ years). Furthermore, multiple linear regression models incorporating both absorbance and fluorescence variables proved capable of explaining much of the variability in lignin composition across rivers and seasons. Our findings suggest that synoptic, high-resolution optical measurements can provide improved understanding of northern high-latitude organic matter cycling and flux, and prove an important technique for capturing future climate-driven changes.
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Pan-arctic trends in terrestrial dissolved organic matter from optical measurements
Mann, Paul J.; Spencer, Robert G. M.; Hernes, Peter J.; Six, Johan; Aiken, George R.; Tank, Suzanne E.; McClelland, James W.; Butler, Kenna D.; Dyda, Rachael Y.; Holmes, Robert M.
2016-01-01
Climate change is causing extensive warming across Arctic regions resulting in permafrost degradation, alterations to regional hydrology and shifting amounts and composition of dissolved organic matter (DOM) transported by streams and rivers. Here, we characterize the DOM composition and optical properties of the six largest Arctic rivers draining into the Arctic Ocean to examine the ability of optical measurements to provide meaningful insights into terrigenous carbon export patterns and biogeochemical cycling. The chemical composition of aquatic DOM varied with season, spring months were typified by highest lignin phenol and dissolved organic carbon (DOC) concentrations with greater hydrophobic acid content, and lower proportions of hydrophilic compounds, relative to summer and winter months. Chromophoric DOM (CDOM) spectral slope (S275–295) tracked seasonal shifts in DOM composition across river basins. Fluorescence and parallel factor analysis identified seven components across the six Arctic rivers. The ratios of “terrestrial humic-like” vs. “marine humic-like” fluorescent components co-varied with lignin monomer ratios over summer and winter months, suggesting fluorescence may provide information on the age and degradation state of riverine DOM. CDOM absorbance (a350) proved a sensitive proxy for lignin phenol concentrations across all six river basins and over the hydrograph, enabling for the first time the development of a single pan-arctic relationship between a350 and terrigenous DOC (R2 = 0.93). Combining this lignin proxy with high-resolution monitoring of a350, pan-arctic estimates of annual lignin flux were calculated to range from 156 to 185 Gg, resulting in shorter and more constrained estimates of terrigenous DOM residence times in the Arctic Ocean (spanning 7 months to 2½ years). Furthermore, multiple linear regression models incorporating both absorbance and fluorescence variables proved capable of explaining much of the variability in lignin composition across rivers and seasons. Our findings suggest that synoptic, high-resolution optical measurements can provide improved understanding of northern high-latitude organic matter cycling and flux, and prove an important technique for capturing future climate-driven changes.
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Counterfeit-resistant materials and a method and apparatus for authenticating materials
Ramsey, J. Michael; Klatt, Leon N.
2001-01-01
Fluorescent dichroic fibers randomly incorporated within a media provide an improved method for authentication and counterfeiting protection. The dichroism is provided by an alignment of fluorescent molecules along the length of the fibers. The fluorescent fibers provide an authentication mechanism of varying levels of capability. The authentication signature depends on four parameters, the x,y position, the dichroism and the local environment. The availability of so many non-deterministic variables makes production of counterfeit articles (e.g., currency, credit cards, etc.) essentially impossible Counterfeit-resistant articles, an apparatus for authenticating articles, and a process for forming counterfeit-resistant media are also provided&
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Counterfeit-resistant materials and a method and apparatus for authenticating materials
Ramsey, J. Michael; Klatt, Leon N.
2000-01-01
Fluorescent dichroic fibers randomly incorporated within a media provide an improved method for authentication and counterfeiting protection. The dichroism is provided by an alignment of fluorescent molecules along the length of the fibers. The fluorescent fibers provide an authentication mechanism of varying levels of capability. The authentication signature depends on four parameters; the x,y position, the dichroism and the local environment. The availability of so many non-deterministic variables makes production of counterfeit articles (e.g., currency, credit cards, etc.) essentially impossible. Counterfeit-resistant articles, an apparatus for authenticating articles, and a process for forming counterfeit-resistant media are also provided.
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Discrimination of corn from monocotyledonous weeds with ultraviolet (UV) induced fluorescence.
Panneton, Bernard; Guillaume, Serge; Samson, Guy; Roger, Jean-Michel
2011-01-01
In production agriculture, savings in herbicides can be achieved if weeds can be discriminated from crop, allowing the targeting of weed control to weed-infested areas only. Previous studies demonstrated the potential of ultraviolet (UV) induced fluorescence to discriminate corn from weeds and recently, robust models have been obtained for the discrimination between monocots (including corn) and dicots. Here, we developed a new approach to achieve robust discrimination of monocot weeds from corn. To this end, four corn hybrids (Elite 60T05, Monsanto DKC 26-78, Pioneer 39Y85 (RR), and Syngenta N2555 (Bt, LL)) and four monocot weeds (Digitaria ischaemum (Schreb.) I, Echinochloa crus-galli (L.) Beauv., Panicum capillare (L.), and Setaria glauca (L.) Beauv.) were grown either in a greenhouse or in a growth cabinet and UV (327 nm) induced fluorescence spectra (400 to 755 nm) were measured under controlled or uncontrolled ambient light intensity and temperature. This resulted in three contrasting data sets suitable for testing the robustness of discrimination models. In the blue-green region (400 to 550 nm), the shape of the spectra did not contain any useful information for discrimination. Therefore, the integral of the blue-green region (415 to 455 nm) was used as a normalizing factor for the red fluorescence intensity (670 to 755 nm). The shape of the normalized red fluorescence spectra did not contribute to the discrimination and in the end, only the integral of the normalized red fluorescence intensity was left as a single discriminant variable. Applying a threshold on this variable minimizing the classification error resulted in calibration errors ranging from 14.2% to 15.8%, but this threshold varied largely between data sets. Therefore, to achieve robustness, a model calibration scheme was developed based on the collection of a calibration data set from 75 corn plants. From this set, a new threshold can be estimated as the 85% quantile on the cumulative frequency curve of the integral of the normalized red fluorescence. With this approach the classification error was nearly constant (16.0% to 18.5%), thereby indicating the potential of UV-induced fluorescence to reliably discriminate corn from monocot weeds.
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Ma, Dinglong; Bec, Julien; Yankelevich, Diego R.; Gorpas, Dimitris; Fatakdawala, Hussain; Marcu, Laura
2014-01-01
Abstract. We report the development and validation of a hybrid intravascular diagnostic system combining multispectral fluorescence lifetime imaging (FLIm) and intravascular ultrasound (IVUS) for cardiovascular imaging applications. A prototype FLIm system based on fluorescence pulse sampling technique providing information on artery biochemical composition was integrated with a commercial IVUS system providing information on artery morphology. A customized 3-Fr bimodal catheter combining a rotational side-view fiberoptic and a 40-MHz IVUS transducer was constructed for sequential helical scanning (rotation and pullback) of tubular structures. Validation of this bimodal approach was conducted in pig heart coronary arteries. Spatial resolution, fluorescence detection efficiency, pulse broadening effect, and lifetime measurement variability of the FLIm system were systematically evaluated. Current results show that this system is capable of temporarily resolving the fluorescence emission simultaneously in multiple spectral channels in a single pullback sequence. Accurate measurements of fluorescence decay characteristics from arterial segments can be obtained rapidly (e.g., 20 mm in 5 s), and accurate co-registration of fluorescence and ultrasound features can be achieved. The current finding demonstrates the compatibility of FLIm instrumentation with in vivo clinical investigations and its potential to complement conventional IVUS during catheterization procedures. PMID:24898604
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Effects of Recent Regional Soil Moisture Variability on Global Net Ecosystem CO2 Exchange
NASA Astrophysics Data System (ADS)
Jones, L. A.; Madani, N.; Kimball, J. S.; Reichle, R. H.; Colliander, A.
2017-12-01
Soil moisture exerts a major regional control on the inter-annual variability of the global land sink for atmospheric CO2. In semi-arid regions, annual biomass production is closely coupled to variability in soil moisture availability, while in cold-season-affected regions, summer drought offsets the effects of advancing spring phenology. Availability of satellite solar-induced fluorescence (SIF) observations and improvements in atmospheric inversions has led to unprecedented ability to monitor atmospheric sink strength. However, discrepancies still exist between such top-down estimates as atmospheric inversion and bottom-up process and satellite driven models, indicating that relative strength, mechanisms, and interaction of driving factors remain poorly understood. We use soil moisture fields informed by Soil Moisture Active Passive Mission (SMAP) observations to compare recent (2015-2017) and historic (2000-2014) variability in net ecosystem land-atmosphere CO2 exchange (NEE). The operational SMAP Level 4 Carbon (L4C) product relates ground-based flux tower measurements to other bottom-up and global top-down estimates to underlying soil moisture and other driving conditions using data-assimilation-based SMAP Level 4 Soil Moisture (L4SM). Droughts in coastal Brazil, South Africa, Eastern Africa, and an anomalous wet period in Eastern Australia were observed by L4C. A seasonal seesaw pattern of below-normal sink strength at high latitudes relative to slightly above-normal sink strength for mid-latitudes was also observed. Whereas SMAP-based soil moisture is relatively informative for short-term temporal variability, soil moisture biases that vary in space and with season constrain the ability of the L4C estimates to accurately resolve NEE. Such biases might be caused by irrigation and plant-accessible ground-water. Nevertheless, SMAP L4C daily NEE estimates connect top-down estimates to variability of effective driving factors for accurate estimates of regional-to-global land-atmosphere CO2 exchange.
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Rich, Ryan M; Stankowska, Dorota L; Maliwal, Badri P; Sørensen, Thomas Just; Laursen, Bo W; Krishnamoorthy, Raghu R; Gryczynski, Zygmunt; Borejdo, Julian; Gryczynski, Ignacy; Fudala, Rafal
2013-02-01
Sample autofluorescence (fluorescence of inherent components of tissue and fixative-induced fluorescence) is a significant problem in direct imaging of molecular processes in biological samples. A large variety of naturally occurring fluorescent components in tissue results in broad emission that overlaps the emission of typical fluorescent dyes used for tissue labeling. In addition, autofluorescence is characterized by complex fluorescence intensity decay composed of multiple components whose lifetimes range from sub-nanoseconds to a few nanoseconds. For these reasons, the real fluorescence signal of the probe is difficult to separate from the unwanted autofluorescence. Here we present a method for reducing the autofluorescence problem by utilizing an azadioxatriangulenium (ADOTA) dye with a fluorescence lifetime of approximately 15 ns, much longer than those of most of the components of autofluorescence. A probe with such a long lifetime enables us to use time-gated intensity imaging to separate the signal of the targeting dye from the autofluorescence. We have shown experimentally that by discarding photons detected within the first 20 ns of the excitation pulse, the signal-to-background ratio is improved fivefold. This time-gating eliminates over 96 % of autofluorescence. Analysis using a variable time-gate may enable quantitative determination of the bound probe without the contributions from the background.
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Ethidium bromide as a marker of mtDNA replication in living cells
NASA Astrophysics Data System (ADS)
Villa, Anna Maria; Fusi, Paola; Pastori, Valentina; Amicarelli, Giulia; Pozzi, Chiara; Adlerstein, Daniel; Doglia, Silvia Maria
2012-04-01
Mitochondrial DNA (mtDNA) in tumor cells was found to play an important role in maintaining the malignant phenotype. Using laser scanning confocal fluorescence microscopy (LSCFM) in a recent work, we reported a variable fluorescence intensity of ethidium bromide (EB) in mitochondria nucleoids of living carcinoma cells. Since when EB is bound to nucleic acids its fluorescence is intensified; a higher EB fluorescence intensity could reflect a higher DNA accessibility to EB, suggesting a higher mtDNA replication activity. To prove this hypothesis, in the present work we studied, by LSCFM, the EB fluorescence in mitochondria nucleoids of living neuroblastoma cells, a model system in which differentiation affects the level of mtDNA replication. A drastic decrease of fluorescence was observed after differentiation. To correlate EB fluorescence intensity to the mtDNA replication state, we evaluated the mtDNA nascent strands content by ligation-mediated real-time PCR, and we found a halved amount of replicating mtDNA molecules in differentiating cells. A similar result was obtained by BrdU incorporation. These results indicate that the low EB fluorescence of nucleoids in differentiated cells is correlated to a low content of replicating mtDNA, suggesting that EB may be used as a marker of mtDNA replication in living cells.
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Near-infrared surface-enhanced fluorescence using silver nanoparticles in solution
NASA Astrophysics Data System (ADS)
Furtaw, Michael D.
Fluorescence spectroscopy is a widely used detection technology in many research and clinical assays. Further improvement to assay sensitivity may enable earlier diagnosis of disease, novel biomarker discovery, and ultimately, improved outcomes of clinical care along with reduction in costs. Near-infrared, surface-enhanced fluorescence (NIR-SEF) is a promising approach to improve assay sensitivity via simultaneous increase in signal with a reduction in background. This dissertation describes research conducted with the overall goal to determine the extent to which fluorescence in solution may be enhanced by altering specific variables involved in the formation of plasmon-active nanostructures of dye-labeled protein and silver nanoparticles in solution, with the intent of providing a simple solution that may be readily adopted by current fluorescence users in the life science research community. First, it is shown that inner-filtering, re-absorption of the emitted photons, can red-shift the optimal fluorophore spectrum away from the resonant frequency of the plasmon-active nanostructure. It is also shown that, under certain conditions, the quality factor may be a better indicator of SEF than the commonly accepted overlap of the fluorophore spectrum with the plasmon resonance of the nanostructure. Next, it is determined that streptavidin is the best choice for carrier protein, among the most commonly used dye-labeled detection antibodies, to enable the largest fluorescence enhancement when labeled with IRDye 800CW and used in combination with silver nanoparticles in solution. It is shown that the relatively small and symmetric geometry of streptavidin enables substantial electromagnetic-field confinement when bound to silver nanoparticles, leading to strong and reproducible enhancement. The role of silver nanoparticle aggregation is demonstrated in a droplet-based microfluidic chip and further optimized in a standard microtiter-plate format. A NIR-SEF technology based on aggregation with optimized salt concentration demonstrates a fluorescence signal enhancement up to 2530-fold while improving the limit-of-detection over 1000-fold. Finally, the NIR-SEF technology is applied to demonstrate 42-fold improvement in sensitivity of the clinically-relevant biomarker, alpha-fetoprotein, along with a 16-fold improvement in limit-of-detection.
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Patalay, Rakesh; Talbot, Clifford; Alexandrov, Yuriy; Munro, Ian; Neil, Mark A. A.; König, Karsten; French, Paul M. W.; Chu, Anthony; Stamp, Gordon W.; Dunsby, Chris
2011-01-01
We explore the diagnostic potential of imaging endogenous fluorophores using two photon microscopy and fluorescence lifetime imaging (FLIM) in human skin with two spectral detection channels. Freshly excised benign dysplastic nevi (DN) and malignant nodular Basal Cell Carcinomas (nBCCs) were excited at 760 nm. The resulting fluorescence signal was binned manually on a cell by cell basis. This improved the reliability of fitting using a double exponential decay model and allowed the fluorescence signatures from different cell populations within the tissue to be identified and studied. We also performed a direct comparison between different diagnostic groups. A statistically significant difference between the median mean fluorescence lifetime of 2.79 ns versus 2.52 ns (blue channel, 300-500 nm) and 2.08 ns versus 1.33 ns (green channel, 500-640 nm) was found between nBCCs and DN respectively, using the Mann-Whitney U test (p < 0.01). Further differences in the distribution of fluorescence lifetime parameters and inter-patient variability are also discussed. PMID:22162820
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Angular shaping of fluorescence from synthetic opal-based photonic crystal.
Boiko, Vitalii; Dovbeshko, Galyna; Dolgov, Leonid; Kiisk, Valter; Sildos, Ilmo; Loot, Ardi; Gorelik, Vladimir
2015-01-01
Spectral, angular, and temporal distributions of fluorescence as well as specular reflection were investigated for silica-based artificial opals. Periodic arrangement of nanosized silica globules in the opal causes a specific dip in the defect-related fluorescence spectra and a peak in the reflectance spectrum. The spectral position of the dip coincides with the photonic stop band. The latter is dependent on the size of silica globules and the angle of observation. The spectral shape and intensity of defect-related fluorescence can be controlled by variation of detection angle. Fluorescence intensity increases up to two times at the edges of the spectral dip. Partial photobleaching of fluorescence was observed. Photonic origin of the observed effects is discussed.
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Chen, Qiuying; Hirsch, Rhoda Elison
2006-03-01
Fluorescence emission of free protoporphyrin IX (PPIX, em. approximately 626 nm), zinc protoporphyrin IX (ZPP, em. approximately 594 nm) and fluorescent heme degradation product (FHDP, em. approximately 466 nm) are identified and simultaneously detected in mouse and human red cell hemolysates, when excited at 365 nm. A novel method is established for comparing relative FHDP, PPIX and ZPP levels in hemolysates without performing red cell porphyrin extractions. The ZPP fluorescence directly measured in hemolysates (F(365/594)) correlates with the ZPP fluorescence obtained from acetone/water extraction (R(2) = 0.9515, P < 0.0001). The relative total porphyrin (ZPP and PPIX) fluorescence obtained from direct hemolysate fluorescence measurements also correlates with red blood cell total porphyrins determined by ethyl acetate extraction (Piomelli extraction, R(2) = 0.88, P < 0.0001). These fluorescent species serves as biomarkers for alterations in Hb synthesis and Hb stability.
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Analysis of rainwater dissolved organic carbon compounds using fluorescence spectrophotometry
NASA Astrophysics Data System (ADS)
Muller, Catherine L.; Baker, Andy; Hutchinson, Robert; Fairchild, Ian J.; Kidd, Chris
Global rainwater dissolved organic carbon (DOC) flux was recently estimated as 430 × 10 12 g C yr -1, yet little is known about the wide range of chemical compounds present, their sources, temporal patterns of variation, and the subsequent impact on climate and the environment. Precipitation events were sampled in Birmingham, UK between April 2005 and May 2007. Rainwater DOC compounds were analysed using fluorescence spectrophotometry. Three fluorophores were identified: HUmic-LIke Substances (HULIS), TYrosine-LIke Substances (TYLIS) and TRYptophan-LIke Substances (TRYLIS). Peak fluorescence intensities and locations for each substance were examined, and their variations with various meteorological parameters were investigated. The mean HULIS fluorescence intensity from all events was 209 a.u. (with sample fluorescence ranging from 37 a.u. to 995 a.u); mean fluorescence intensity was 469 a.u. (214-988 a.u) and 265 a.u. (50-876 a.u.) for TYLIS and TRYLIS, respectively. Results indicate that highest HULIS fluorescence intensities are experienced during convective events and events of continental origin, suggesting terrestrial/anthropogenic sources. Under well-mixed conditions, HULIS fluorescence intensity decreases, whereas during low wind speed, stagnation of the atmosphere results in higher fluorescence intensities, attributed to a build up of localised sources, particularly anthropogenic. TYLIS and TRYLIS did not show any significant trends for the meteorological variables. Fluorescence spectrophotometry is a fast, non-invasive technique which is demonstrated to be a powerful means of fingerprinting rainfall DOC compounds in real time for small sample volumes.
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Rapid spectrofluorometric screening of poly-hydroxyalkanoate-producing bacteria from microbial mats.
Berlanga, Mercedes; Montero, M T; Fernández-Borrell, Jordi; Guerrero, Ricardo
2006-06-01
Microbial mat ecosystems are characterized by both seasonal and diel fluctuations in several physicochemical variables, so that resident microorganisms must frequently adapt to the changing conditions of their environment. It has been pointed out that, under stress conditions, bacterial cells with higher contents of poly-hydroxyalkanoates (PHA) survive longer than those with lower PHA content. In the present study, PHA-producing strains from Ebro Delta microbial mats were selected using the Nile red dying technique and the relative accumulation of PHA was monitored during further laboratory cultivation. The number of heterotrophic isolates in trypticase soy agar (TSA) was ca. 107 colony-forming units/g microbial mat. Of these, 100 randomly chosen colonies were replicated on mineral salt agar limited in nitrogen, and Nile red was added to the medium to detect PHA. Orange fluorescence, produced upon binding of the dye to polymer granules in the cell, was detected in approximately 10% of the replicated heterotrophic isolates. The kinetics of PHA accumulation in Pseudomonas putida, and P. oleovorans were compared with those of several of the environmental isolates spectrofluorometry. PHA accumulation, measured as relative fluorescence intensity, resulted in a steady-state concentration after 48 h of incubation in all strains assayed. At 72 h, the maximum fluorescence intensity of each strain incubated with glucose and fructose was usually similar. MAT-28 strain accumulated more PHA than the other isolates. The results show that data obtained from environmental isolates can highly improve studies based on modeling-simulation programs, and that microbial mats constitute an excellent source for the isolation of PHA-producing strains with industrial applications.
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Monitoring of an antigen manufacturing process.
Zavatti, Vanessa; Budman, Hector; Legge, Raymond; Tamer, Melih
2016-06-01
Fluorescence spectroscopy in combination with multivariate statistical methods was employed as a tool for monitoring the manufacturing process of pertactin (PRN), one of the virulence factors of Bordetella pertussis utilized in whopping cough vaccines. Fluorophores such as amino acids and co-enzymes were detected throughout the process. The fluorescence data collected at different stages of the fermentation and purification process were treated employing principal component analysis (PCA). Through PCA, it was feasible to identify sources of variability in PRN production. Then, partial least square (PLS) was employed to correlate the fluorescence spectra obtained from pure PRN samples and the final protein content measured by a Kjeldahl test from these samples. In view that a statistically significant correlation was found between fluorescence and PRN levels, this approach could be further used as a method to predict the final protein content.
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Simple device for the direct visualization of oral-cavity tissue fluorescence
NASA Astrophysics Data System (ADS)
Lane, Pierre M.; Gilhuly, Terence; Whitehead, Peter D.; Zeng, Haishan; Poh, Catherine; Ng, Samson; Williams, Michelle; Zhang, Lewei; Rosin, Miriam; MacAulay, Calum E.
2006-03-01
Early identification of high-risk disease could greatly reduce both mortality and morbidity due to oral cancer. We describe a simple handheld device that facilitates the direct visualization of oral-cavity fluorescence for the detection of high-risk precancerous and early cancerous lesions. Blue excitation light (400 to 460 nm) is employed to excite green-red fluorescence from fluorophores in the oral tissues. Tissue fluorescence is viewed directly along an optical axis collinear with the axis of excitation to reduce inter- and intraoperator variability. This robust, field-of-view device enables the direct visualization of fluorescence in the context of surrounding normal tissue. Results from a pilot study of 44 patients are presented. Using histology as the gold standard, the device achieves a sensitivity of 98% and specificity of 100% when discriminating normal mucosa from severe dysplasia/carcinoma in situ (CIS) or invasive carcinoma. We envisage this device as a suitable adjunct for oral cancer screening, biopsy guidance, and margin delineation.
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Comparative assessment of fluorescent proteins for in vivo imaging in an animal model system.
Heppert, Jennifer K; Dickinson, Daniel J; Pani, Ariel M; Higgins, Christopher D; Steward, Annette; Ahringer, Julie; Kuhn, Jeffrey R; Goldstein, Bob
2016-11-07
Fluorescent protein tags are fundamental tools used to visualize gene products and analyze their dynamics in vivo. Recent advances in genome editing have expedited the precise insertion of fluorescent protein tags into the genomes of diverse organisms. These advances expand the potential of in vivo imaging experiments and facilitate experimentation with new, bright, photostable fluorescent proteins. Most quantitative comparisons of the brightness and photostability of different fluorescent proteins have been made in vitro, removed from biological variables that govern their performance in cells or organisms. To address the gap, we quantitatively assessed fluorescent protein properties in vivo in an animal model system. We generated transgenic Caenorhabditis elegans strains expressing green, yellow, or red fluorescent proteins in embryos and imaged embryos expressing different fluorescent proteins under the same conditions for direct comparison. We found that mNeonGreen was not as bright in vivo as predicted based on in vitro data but is a better tag than GFP for specific kinds of experiments, and we report on optimal red fluorescent proteins. These results identify ideal fluorescent proteins for imaging in vivo in C. elegans embryos and suggest good candidate fluorescent proteins to test in other animal model systems for in vivo imaging experiments. © 2016 Heppert et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).
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Blajman, J E; Astesana, D M; Zimmermann, J A; Rossler, E; Scharpen, A Romero; Berisvil, A P; Zbrun, M V; Soto, L P; Rosmini, M R; Frizzo, L S
2017-02-07
The knowledge related to the fate of probiotics in the complex environment of the intestinal microbiota in broilers is just beginning to be elucidated; however, it is not yet well understood. A good method to investigate the mechanisms by which probiotics mediate their effects is to mark probiotic bacteria and trace them. The aim of this research was to develop a new method to estimate in vivo fluorescein isothiocyanate (FITC)-labelled Lactobacillus salivarius DSPV 001P counts during passage through the gastrointestinal tract (GIT) of broilers. Forty-five, 1 d old Cobb broilers were used in this trial. Programmed necropsies were performed 30 min, 6 h, and 12 h after the administration of the probiotic bacterium, and samples of liver, crop, duodenum, caecum, and bursa of fabricius were collected. To determine the spatial and temporal transit of L. salivarius DSPV 001P in broilers, the number of bacteria as well as its respective fluorescent signal produced by FITC were measured. In order to observe the relationship between the variables, a logistic regression analysis was applied. The amount of fluorescence could be used as an indicator of fluorescent probiotic bacteria in the crop and duodenum 30 min after probiotic bacterium supplementation. In addition, the fluorescent signal could be used to estimate bacterial counts in caecum 6 and 12 h after L. salivarius DSPV 001P administration. To the best of our knowledge, this research is the first in vivo trial to employ the bacterial FITC-labelling technique in order to enumerate probiotic bacteria during gastrointestinal transit in broilers.
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NASA Astrophysics Data System (ADS)
Zhou, Xin; Jun, Sun; Zhang, Bing; Jun, Wu
2017-07-01
In order to improve the reliability of the spectrum feature extracted by wavelet transform, a method combining wavelet transform (WT) with bacterial colony chemotaxis algorithm and support vector machine (BCC-SVM) algorithm (WT-BCC-SVM) was proposed in this paper. Besides, we aimed to identify different kinds of pesticide residues on lettuce leaves in a novel and rapid non-destructive way by using fluorescence spectra technology. The fluorescence spectral data of 150 lettuce leaf samples of five different kinds of pesticide residues on the surface of lettuce were obtained using Cary Eclipse fluorescence spectrometer. Standard normalized variable detrending (SNV detrending), Savitzky-Golay coupled with Standard normalized variable detrending (SG-SNV detrending) were used to preprocess the raw spectra, respectively. Bacterial colony chemotaxis combined with support vector machine (BCC-SVM) and support vector machine (SVM) classification models were established based on full spectra (FS) and wavelet transform characteristics (WTC), respectively. Moreover, WTC were selected by WT. The results showed that the accuracy of training set, calibration set and the prediction set of the best optimal classification model (SG-SNV detrending-WT-BCC-SVM) were 100%, 98% and 93.33%, respectively. In addition, the results indicated that it was feasible to use WT-BCC-SVM to establish diagnostic model of different kinds of pesticide residues on lettuce leaves.
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NASA Astrophysics Data System (ADS)
Smith, W. K.; Biederman, J. A.; Scott, R. L.; Moore, D. J.; Kimball, J. S.; He, M.; Yan, D.; Hudson, A.; Barnes, M.; MacBean, N.; Fox, A. M.; Litvak, M. E.
2017-12-01
Satellite remote sensing provides unmatched spatiotemporal information on multiple facets of vegetation dynamics including seasonal to interannual total photosynthesis, termed gross primary productivity (GPP). Yet, our understanding of the relationship between GPP and remote sensing observations - and how this relationship changes with scale, biophysical constraint, vegetation type, etc. - remains limited. This knowledge gap is especially apparent for dryland ecosystems, which have high spatial and temporal variability and are under-represented by long-term, continuous field measurements. Here, utilizing a new synthesis of eddy covariance flux tower data for southwestern North America, we present a first assessment of the ability of novel satellite remote sensing vegetation proxies to accurately capture seasonal to interannual GPP dynamics across the region. We evaluate the greenness-based Enhanced Vegetation Index (EVI) and emerging proxies linked to plant physiological function, Solar-Induced Fluorescence (SIF) and Photochemical Reflectivity Index (PRI). We find that SIF observations more consistently correlate with seasonal GPP dynamics (R = 0.90) compared to EVI (R = 0.85) and PRI (R = 0.78). More, we find that SIF observations are also more sensitive to interannual GPP variability (linear slope = 0.80) relative to EVI (linear slope = 0.63) and PRI (linear slope = 0.35). This is likely due to increased sensitivity of SIF to GPP during periods of decoupling between greenness and photosynthesis due to water-limitation / stomatal closure. Conversely, EVI and PRI observations better capture spatial GPP variability between flux tower sites. These results suggest that combinations of these independent vegetation growth proxies could yield synergistic improvements in satellite-based GPP estimates.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Leadly, T.A.; Haffner, G.D.; Arcand-Hoy, L.D.
1999-04-01
Analysis of fluorescent aromatic compounds (FACs) in the bile of fish has been widely used as a biomarker of exposure to polynuclear aromatic hydrocarbon (PAH) contamination. However, bile FAC data for feral fish populations are typically highly variable, and in a few cases, elevation of FACs has not been observed in fish from contaminated areas. In this study, the bile FACs and hepatic ethoxyresorufin-O-deethylase activity in brown bullheads (Ameiurus nebulosus) exposed in the laboratory to contaminated sediments from Hamilton Harbour, Ontario, Canada, increased by 173-fold within 72 h of initial exposure and rapidly declined thereafter. In bullheads caged in themore » contaminated Trenton Channel area of the Detroit River, bile FACs also increased rapidly within 4 d of initial exposure to mean levels >3,000 ng of benzo[a]pyrene equivalents per milliliter of bile. Surprisingly, there was no difference in the mean-levels of bile FACs in fish caged above the sediment versus fish caged in direct contact with the sediment, indicating that water may be the major vector for uptake of PAHs. The lower bile FACs in bullheads caged in other regions of the Detroit River were consistent with the lower concentrations of PAHs in the sediments from these areas. These data indicate that bile FAC levels are a biomarker of recent exposure to aromatic hydrocarbons in sediments. However, FAC data were highly variable even in these studies, in which fish were relatively homogenous in size, feeding status, and exposure history. Therefore, Even higher variability in bile FAC data are expected in biomarker studies as a result of differences in reproductive status, size, diet, and mobility of the fish.« less
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Laser-Induced Fluorescence (LIF) from plant foliage
NASA Technical Reports Server (NTRS)
Chappelle, E. W.; Williams, D. L.
1986-01-01
The fluorescence spectra and fluorescence induction kinetics of green plants excited at 337 nm by a laser were studied. They correlate with plant type, as well as with changes in the physiology of the plant as the result of stress. The plant types studied include herbaceous dicots, monocots, hardwoods, conifers, and algae. These plant types could be identified on the basis of differences in either the number of fluorescent bands or the relative intensity of the bands. Differences in fluorescent spectra which could be related to vigor status are observed in conifers located in an area of high atmospheric deposition. Changes in the fluorescence spectra and induction kinetics are also seen in plants grown under conditions of nutrient deficiency and drought stress.
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Laser-Induced Fluorescence (LIF) from plant foliage
NASA Technical Reports Server (NTRS)
Chappelle, Emmett W.; Williams, Darrel L.
1987-01-01
The fluorescence spectra and fluorescence induction kinetics of green plants excited at 337 nm by a laser were studied. They correlate with plant type, as well as with changes in the physiology of the plant as the result of stress. The plant types studied include herbaceous dicots, monocots, hardwoods, conifers, and algae. These plant types could be identified on the basis of differences in either the number of fluorescent bands or the relative intensity of the bands. Differences in fluorescent spectra which could be related to vigor status are observed in conifers located in an area of high atmospheric deposition. Changes in the fluorescence spectra and induction kinetics are also seen in plants grown under conditions of nutrient deficiency and drought stress.
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NASA Astrophysics Data System (ADS)
Shirshin, Evgeny; Cherkasova, Olga; Tikhonova, Tatiana; Berlovskaya, Elena; Priezzhev, Alexander; Fadeev, Victor
2015-05-01
We present the results of a native fluorescence spectroscopy study of blood plasma of rats with experimental diabetes. It was shown that the fluorescence emission band shape at 320 nm excitation is the most indicative of hyperglycemia in the blood plasma samples. We provide the interpretation of this fact based on the changes in reduced nicotinamide adenine dinucleotide phosphate concentration due to glucose-related metabolic pathways and protein fluorescent cross-linking formation following nonenzymatic glycation.
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Yang, Zhongqin; Hu, Bihe; Zhang, Yuhui; Luo, Qingming; Gong, Hui
2013-01-01
Fluorescent proteins serve as important biomarkers for visualizing both subcellular organelles in living cells and structural and functional details in large-volume tissues or organs. However, current techniques for plastic embedding are limited in their ability to preserve fluorescence while remaining suitable for micro-optical sectioning tomography of large-volume samples. In this study, we quantitatively evaluated the fluorescence preservation and penetration time of several commonly used resins in a Thy1-eYFP-H transgenic whole mouse brain, including glycol methacrylate (GMA), LR White, hydroxypropyl methacrylate (HPMA) and Unicryl. We found that HMPA embedding doubled the eYFP fluorescence intensity but required long durations of incubation for whole brain penetration. GMA, Unicryl and LR White each penetrated the brain rapidly but also led to variable quenching of eYFP fluorescence. Among the fast-penetrating resins, GMA preserved fluorescence better than LR White and Unicryl. We found that we could optimize the GMA formulation by reducing the polymerization temperature, removing 4-methoxyphenol and adjusting the pH of the resin solution to be alkaline. By optimizing the GMA formulation, we increased percentage of eYFP fluorescence preservation in GMA-embedded brains nearly two-fold. These results suggest that modified GMA is suitable for embedding large-volume tissues such as whole mouse brain and provide a novel approach for visualizing brain-wide networks. PMID:23577174
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PDT dose dosimetry for Photofrin-mediated pleural photodynamic therapy (pPDT)
NASA Astrophysics Data System (ADS)
Ong, Yi Hong; Kim, Michele M.; Finlay, Jarod C.; Dimofte, Andreea; Singhal, Sunil; Glatstein, Eli; Cengel, Keith A.; Zhu, Timothy C.
2018-01-01
Photosensitizer fluorescence excited by photodynamic therapy (PDT) treatment light can be used to monitor the in vivo concentration of the photosensitizer and its photobleaching. The temporal integral of the product of in vivo photosensitizer concentration and light fluence is called PDT dose, which is an important dosimetry quantity for PDT. However, the detected photosensitizer fluorescence may be distorted by variations in the absorption and scattering of both excitation and fluorescence light in tissue. Therefore, correction of the measured fluorescence for distortion due to variable optical properties is required for absolute quantification of photosensitizer concentration. In this study, we have developed a four-channel PDT dose dosimetry system to simultaneously acquire light dosimetry and photosensitizer fluorescence data. We measured PDT dose at four sites in the pleural cavity during pleural PDT. We have determined an empirical optical property correction function using Monte Carlo simulations of fluorescence for a range of physiologically relevant tissue optical properties. Parameters of the optical property correction function for Photofrin fluorescence were determined experimentally using tissue-simulating phantoms. In vivo measurements of photosensitizer fluorescence showed negligible photobleaching of Photofrin during the PDT treatment, but large intra- and inter-patient heterogeneities of in vivo Photofrin concentration are observed. PDT doses delivered to 22 sites in the pleural cavity of 8 patients were different by 2.9 times intra-patient and 8.3 times inter-patient.
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Rich, Ryan M.; Stankowska, Dorota L.; Maliwal, Badri P.; Sørensen, Thomas Just; Laursen, Bo W.; Krishnamoorthy, Raghu R.; Gryczynski, Zygmunt; Borejdo, Julian
2013-01-01
Sample autofluorescence (fluorescence of inherent components of tissue and fixative-induced fluorescence) is a significant problem in direct imaging of molecular processes in biological samples. A large variety of naturally occurring fluorescent components in tissue results in broad emission that overlaps the emission of typical fluorescent dyes used for tissue labeling. In addition, autofluorescence is characterized by complex fluorescence intensity decay composed of multiple components whose lifetimes range from sub-nanoseconds to a few nanoseconds. For these reasons, the real fluorescence signal of the probe is difficult to separate from the unwanted autofluorescence. Here we present a method for reducing the autofluorescence problem by utilizing an azadioxatriangulenium (ADOTA) dye with a fluorescence lifetime of approximately 15 ns, much longer than those of most of the components of autofluorescence. A probe with such a long lifetime enables us to use time-gated intensity imaging to separate the signal of the targeting dye from the autofluorescence. We have shown experimentally that by discarding photons detected within the first 20 ns of the excitation pulse, the signal-to-background ratio is improved fivefold. This time-gating eliminates over 96 % of autofluorescence. Analysis using a variable time-gate may enable quantitative determination of the bound probe without the contributions from the background. PMID:23254457
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ERIC Educational Resources Information Center
Rusak, David A.; James, William H., III; Ferzola, Maria J.; Stefanski, Michael J.
2006-01-01
An experiment related to the measurement of fluorescence lifetime for an undergraduate instrumental analysis or physical chemistry laboratory that highlights relative rates of electronic transitions in molecules and introduces students to data collection of a pulsed signal is illustrated. The experiment of the long fluorescence lifetime of…
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Praveen, Bavishna B; Ashok, Praveen C; Mazilu, Michael; Riches, Andrew; Herrington, Simon; Dholakia, Kishan
2012-07-01
In the field of biomedical optics, Raman spectroscopy is a powerful tool for probing the chemical composition of biological samples. In particular, fiber Raman probes play a crucial role for in vivo and ex vivo tissue analysis. However, the high-fluorescence background typically contributed by the auto fluorescence from both a tissue sample and the fiber-probe interferes strongly with the relatively weak Raman signal. Here we demonstrate the implementation of wavelength-modulated Raman spectroscopy (WMRS) to suppress the fluorescence background while analyzing tissues using fiber Raman probes. We have observed a significant signal-to-noise ratio enhancement in the Raman bands of bone tissue, which have a relatively high fluorescence background. Implementation of WMRS in fiber-probe-based bone tissue study yielded usable Raman spectra in a relatively short acquisition time (∼30 s), notably without any special sample preparation stage. Finally, we have validated its capability to suppress fluorescence on other tissue samples such as adipose tissue derived from four different species.
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RNA aptamers that functionally interact with green fluorescent protein and its derivatives
Shui, Bo; Ozer, Abdullah; Zipfel, Warren; Sahu, Nevedita; Singh, Avtar; Lis, John T.; Shi, Hua; Kotlikoff, Michael I.
2012-01-01
Green Fluorescent Protein (GFP) and related fluorescent proteins (FPs) have been widely used to tag proteins, allowing their expression and subcellular localization to be examined in real time in living cells and animals. Similar fluorescent methods are highly desirable to detect and track RNA and other biological molecules in living cells. For this purpose, we have developed a group of RNA aptamers that bind GFP and related proteins, which we term Fluorescent Protein-Binding Aptamers (FPBA). These aptamers bind GFP, YFP and CFP with low nanomolar affinity and binding decreases GFP fluorescence, whereas slightly augmenting YFP and CFP brightness. Aptamer binding results in an increase in the pKa of EGFP, decreasing the 475 nm excited green fluorescence at a given pH. We report the secondary structure of FPBA and the ability to synthesize functional multivalent dendrimers. FPBA expressed in live cells decreased GFP fluorescence in a valency-dependent manner, indicating that the RNA aptamers function within cells. The development of aptamers that bind fluorescent proteins with high affinity and alter their function, markedly expands their use in the study of biological pathways. PMID:22189104
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Delvigne, Frank; Pêcheux, Hélène; Tarayre, Cédric
2015-01-01
The use of genetically encoded fluorescent reporters allows speeding up the initial optimization steps of microbial bioprocesses. These reporters can be used for determining the expression level of a particular promoter, not only the synthesis of a specific protein but also the content of intracellular metabolites. The level of protein/metabolite is thus proportional to a fluorescence signal. By this way, mean expression profiles of protein/metabolites can be determined non-invasively at a high-throughput rate, allowing the rapid identification of the best producers. Actually, different kinds of reporter systems are available, as well as specific cultivation devices allowing the on-line recording of the fluorescent signal. Cell-to-cell variability is another important phenomenon that can be integrated into the screening procedures for the selection of more efficient microbial cell factories. PMID:26442261
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Ultratrace analysis of transuranic actinides by laser-induced fluorescence
Miller, S.M.
1983-10-31
Ultratrace quantities of transuranic actinides are detected indirectly by their effect on the fluorescent emissions of a preselected fluorescent species. Transuranic actinides in a sample are coprecipitated with a host lattice material containing at least one preselected fluorescent species. The actinide either quenches or enhances the laser-induced fluorescence of the preselected fluorescent species. The degree of enhancement or quenching is quantitatively related to the concentration of actinide in the sample.
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ERIC Educational Resources Information Center
Wall, Kathryn P.; Dillon, Rebecca; Knowles, Michelle K.
2015-01-01
Fluorescent proteins are commonly used in cell biology to assess where proteins are within a cell as a function of time and provide insight into intracellular protein function. However, the usefulness of a fluorescent protein depends directly on the quantum yield. The quantum yield relates the efficiency at which a fluorescent molecule converts…
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Wall, Kathryn P; Dillon, Rebecca; Knowles, Michelle K
2015-01-01
Fluorescent proteins are commonly used in cell biology to assess where proteins are within a cell as a function of time and provide insight into intracellular protein function. However, the usefulness of a fluorescent protein depends directly on the quantum yield. The quantum yield relates the efficiency at which a fluorescent molecule converts absorbed photons into emitted photons and it is necessary to know for assessing what fluorescent protein is the most appropriate for a particular application. In this work, we have designed an upper-level, biochemistry laboratory experiment where students measure the fluorescence quantum yields of fluorescent proteins relative to a standard organic dye. Four fluorescent protein variants, enhanced cyan fluorescent protein (ECFP), enhanced green fluorescent protein (EGFP), mCitrine, and mCherry, were used, however the methods described are useful for the characterization of any fluorescent protein or could be expanded to fluorescent quantum yield measurements of organic dye molecules. The laboratory is designed as a guided inquiry project and takes two, 4 hr laboratory periods. During the first day students design the experiment by selecting the excitation wavelength, choosing the standard, and determining the concentration needed for the quantum yield experiment that takes place in the second laboratory period. Overall, this laboratory provides students with a guided inquiry learning experience and introduces concepts of fluorescence biophysics into a biochemistry laboratory curriculum. © 2014 The International Union of Biochemistry and Molecular Biology.
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Shimabuku, Kyle K; Kennedy, Anthony M; Mulhern, Riley E; Summers, R Scott
2017-03-07
Dissolved organic matter (DOM) negatively impacts granular activated carbon (GAC) adsorption of micropollutants and is a disinfection byproduct precursor. DOM from surface waters, wastewater effluent, and 1 kDa size fractions were adsorbed by GAC and characterized using fluorescence spectroscopy, UV-absorption, and size exclusion chromatography (SEC). Fluorescing DOM was preferentially adsorbed relative to UV-absorbing DOM. Humic-like fluorescence (peaks A and C) was selectively adsorbed relative to polyphenol-like fluorescence (peaks T and B) potentially due to size exclusion effects. In the surface waters and size fractions, peak C was preferentially removed relative to peak A, whereas the reverse was found in wastewater effluent, indicating that humic-like fluorescence is associated with different compounds depending on DOM source. Based on specific UV-absorption (SUVA), aromatic DOM was preferentially adsorbed. The fluorescence index (FI), if interpreted as an indicator of aromaticity, indicated the opposite but exhibited a strong relationship with average molecular weight, suggesting that FI might be a better indicator of DOM size than aromaticity. The influence of DOM intermolecular interactions on adsorption were minimal based on SEC analysis. Fluorescence parameters captured the impact of DOM size on the fouling of 2-methylisoborneol and warfarin adsorption and correlated with direct competition and pore blockage indicators.
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Deng, Yong; Luo, Zhaoyang; Jiang, Xu; Xie, Wenhao; Luo, Qingming
2015-07-01
We propose a method based on a decoupled fluorescence Monte Carlo model for constructing fluorescence Jacobians to enable accurate quantification of fluorescence targets within turbid media. The effectiveness of the proposed method is validated using two cylindrical phantoms enclosing fluorescent targets within homogeneous and heterogeneous background media. The results demonstrate that our method can recover relative concentrations of the fluorescent targets with higher accuracy than the perturbation fluorescence Monte Carlo method. This suggests that our method is suitable for quantitative fluorescence diffuse optical tomography, especially for in vivo imaging of fluorophore targets for diagnosis of different diseases and abnormalities.
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T-FLAP improvement for VOS Program
NASA Astrophysics Data System (ADS)
Marcelli, Marco; Piermattei, Viviana; Madonia, Alice; Mainardi, Umberto; Manzella, Giuseppe M. R.
2010-05-01
The operational oceanography has been engaged in the development of new acquisition, transmission and assimilation systems in order to have the widest possible coverage of real time informations, reflecting the guidelines of the World Meteorological Organization (WMO) and of the Intergovernmental Oceanographic Commission (IOC). Physical and biological processes of marine ecosystems have a high spatial and temporal variability, whose study is possible only through high resolution and synoptic observations. More than for the physical variables, the biological ones have to be observed in situ. Especially in the mid-high latitudes, a deep observation of the water column is needed, because of the typical distribution of phytoplankton's biomass (Mann and Lazier, 1991). In the last times an extensive use of XBT was performed in order to provide near real time analysis of the ocean temperature, but there is still a lack in the biomass estimation. T-FLAP technology (Temperature and Fluorescence LAunchable Probe - Marcelli et al. 2007) was designed to answer to the claim of a cost effective temperature and fluorescence autonomous probe, to be used on ships of opportunity for the Voluntary Observing Ship Program (VOS). During the last three years the probe was upgraded and improved both in materials and in measure sensitivity. New LEDs were mounted to increase the radiant power of the excitation source.. In order to evaluate the red filter efficiency to detect fluorescence chlorophyll a emission wavelengths, transmittance of new available filters in the range 682-685 nm was calculated. In vivo fluorescence spectra of each filter were also performed on samples from Chlorella sp. cultures, to assess the percentage of the fluorescence emission peak transmitted by the filters. A multiple system was designed and realized for a high accuracy dynamic calibration of the probes.
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Yang, Mino
2007-06-07
Theoretical foundation of rate kernel equation approaches for diffusion-influenced chemical reactions is presented and applied to explain the kinetics of fluorescence quenching reactions. A many-body master equation is constructed by introducing stochastic terms, which characterize the rates of chemical reactions, into the many-body Smoluchowski equation. A Langevin-type of memory equation for the density fields of reactants evolving under the influence of time-independent perturbation is derived. This equation should be useful in predicting the time evolution of reactant concentrations approaching the steady state attained by the perturbation as well as the steady-state concentrations. The dynamics of fluctuation occurring in equilibrium state can be predicted by the memory equation by turning the perturbation off and consequently may be useful in obtaining the linear response to a time-dependent perturbation. It is found that unimolecular decay processes including the time-independent perturbation can be incorporated into bimolecular reaction kinetics as a Laplace transform variable. As a result, a theory for bimolecular reactions along with the unimolecular process turned off is sufficient to predict overall reaction kinetics including the effects of unimolecular reactions and perturbation. As the present formulation is applied to steady-state kinetics of fluorescence quenching reactions, the exact relation between fluorophore concentrations and the intensity of excitation light is derived.
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Inducible fluorescent speckle microscopy
Aguiar, Paulo; Belsley, Michael; Maiato, Helder
2016-01-01
The understanding of cytoskeleton dynamics has benefited from the capacity to generate fluorescent fiducial marks on cytoskeleton components. Here we show that light-induced imprinting of three-dimensional (3D) fluorescent speckles significantly improves speckle signal and contrast relative to classic (random) fluorescent speckle microscopy. We predict theoretically that speckle imprinting using photobleaching is optimal when the laser energy and fluorophore responsivity are related by the golden ratio. This relation, which we confirm experimentally, translates into a 40% remaining signal after speckle imprinting and provides a rule of thumb in selecting the laser power required to optimally prepare the sample for imaging. This inducible speckle imaging (ISI) technique allows 3D speckle microscopy to be performed in readily available libraries of cell lines or primary tissues expressing fluorescent proteins and does not preclude conventional imaging before speckle imaging. As a proof of concept, we use ISI to measure metaphase spindle microtubule poleward flux in primary cells and explore a scaling relation connecting microtubule flux to metaphase duration. PMID:26783303
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Inducible fluorescent speckle microscopy.
Pereira, António J; Aguiar, Paulo; Belsley, Michael; Maiato, Helder
2016-01-18
The understanding of cytoskeleton dynamics has benefited from the capacity to generate fluorescent fiducial marks on cytoskeleton components. Here we show that light-induced imprinting of three-dimensional (3D) fluorescent speckles significantly improves speckle signal and contrast relative to classic (random) fluorescent speckle microscopy. We predict theoretically that speckle imprinting using photobleaching is optimal when the laser energy and fluorophore responsivity are related by the golden ratio. This relation, which we confirm experimentally, translates into a 40% remaining signal after speckle imprinting and provides a rule of thumb in selecting the laser power required to optimally prepare the sample for imaging. This inducible speckle imaging (ISI) technique allows 3D speckle microscopy to be performed in readily available libraries of cell lines or primary tissues expressing fluorescent proteins and does not preclude conventional imaging before speckle imaging. As a proof of concept, we use ISI to measure metaphase spindle microtubule poleward flux in primary cells and explore a scaling relation connecting microtubule flux to metaphase duration. © 2016 Pereira et al.
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Laser-induced fluorescence spectroscopy of benign and malignant cutaneous lesions
NASA Astrophysics Data System (ADS)
Borisova, Ekaterina G.; Troyanova, P. P.; Stoyanova, V. P.; Avramov, Lachezar A.
2005-04-01
The goals of this work were investigation of pigmented skin lesions by the method of laser-induced fluorescence spectroscopy. Fluorescence spectra were obtained from malignant and benign skin lesions after excitation with nitrogen laser at 337 nm, namely: benign nevi, dysplastic nevi, malignant melanoma (MM), keratopapilloma, base-cell papilloma and base-cell carcinoma, as well as from healthy skin areas near to the lesion that were used posteriori to reveal changes between healthy and lesion skin spectra. Initially lesions were classified by ABCD-dermatscopic method. All suspicious lesions were excised and were investigated histologically. Spectrum of healthy skin consists of one main maximum at 470-500 nm spectral region and secondary maxima at in the regions round 400 and 440 nm. In the cases of nevi and melanoma significant decrease of fluorescence intensity, which correlated with the type of pigment lesion was observed. This reduction of the signal is related to the accumulation of melanin in the lesions that re-absorb strongly the fluorescence from native skin fluorophores in whole visible spectral region. In cases of papilloma and base-cell carcinoma an intensity decrease was also observed, related to accumulation of pigments in these cutaneous lesions. An relative increase of the fluorescence peak at 440 nm were registered in the case of base-cell carcinoma, and appearance of green fluorescence, related to increase of keratin content in benign papilloma lesions were detected. The results, obtained in this investigation of the different pigment lesions could be used for better comprehension of the skin optical properties. The fluorescence spectroscopy of the human skin are very prominent for early diagnosis and differentiation of cutaneous diseases and gives a wide range of possibilities related to real-time determination of existing pathological condition.
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Jorge, Alexander A L; Souza, Silvia C; Nishi, Miriam Y; Billerbeck, Ana E; Libório, Débora C C; Kim, Chong A; Arnhold, Ivo J P; Mendonca, Berenice B
2007-01-01
The frequency of SHOX mutations in children with idiopathic short stature (ISS) has been found to be variable. We analysed the SHOX gene in children with ISS and Leri-Weill dyschondrosteosis (LWD) and evaluated the phenotypic variability in patients harbouring SHOX mutations. Sixty-three ISS, nine LWD children and 21 affected relatives. SHOX gene deletion was evaluated by fluorescence in situ hybridization (FISH), Southern blotting and segregation study of polymorphic marker. Point mutations were assessed by direct DNA sequencing. None of the ISS patients presented SHOX deletions, but two (3.2%) presented heterozygous point mutations, including the novel R147H mutation. However, when ISS patients were selected by sitting height : height ratio (SH/H) for age > 2 SD, mutation frequency detection increased to 22%. Eight (89%) LWD patients had SHOX deletions, but none had point mutations. Analysis of the other relatives in the families carrying SHOX mutations identified 14 children and 17 adult patients. A broad phenotypic variability was observed in all families regarding short stature severity and Madelung deformities. However, the presence of disproportional height, assessed by SH/H, was observed in all children and 82% of adult patients, being the most common feature in our patients with SHOX mutations. Patients with SHOX mutations present a broad phenotypic variability. SHOX mutations are very frequent in LWD (89%), in opposition to ISS (3.2%) in our cohort. The use of SH/H SDS as a selection criterion increases the frequency of SHOX mutation detection to 22% and should be used for selecting ISS children to undergo SHOX mutation molecular studies.
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NASA Astrophysics Data System (ADS)
Rodriguez, J. M.; Gonzalez-Nuevo, G.; Gonzalez-Pola, C.; Cabal, J.
2009-05-01
Ichthyoplankton and mesozooplankton were sampled and fluorescence and physical environmental variables were measured off the NW and N Iberian Peninsula coasts, during April 2005. A total of 51 species of fish larvae, belonging to 26 families, were recorded. Sardina pilchardus, with 43.8% and 58.7% of the total fish egg and larval catches, respectively, dominated the ichthyoplankton assemblage. The study area was divided by a cross-shelf frontal structure into two hydrographic regions that coincided with the Atlantic and Cantabrian geographic regions. Ichthyoplankton abundance was higher in the Cantabrian region while larval diversity was higher in the Atlantic region. This was the main alongshore variability in the structure of the larval fish assemblage. Nevertheless, the stronger variability, related with the presence of a shelf-slope front, was found in the central-eastern Cantabrian region where two major larval fish assemblages, an "outer" and a "coastal", were distinguished. The Atlantic region, where the shelf-slope front was not found, was inhabited by a single larval fish assemblage. Canonical correspondence analysis revealed that, off the NW and N Iberian Peninsula coasts, the horizontal distribution of larval fish species in early spring may be explained by a limited number of environmental variables. Of these, the most important were the physical variables depth and sea surface temperature.
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Scanning fluorescence detector for high-throughput DNA genotyping
NASA Astrophysics Data System (ADS)
Rusch, Terry L.; Petsinger, Jeremy; Christensen, Carl; Vaske, David A.; Brumley, Robert L., Jr.; Luckey, John A.; Weber, James L.
1996-04-01
A new scanning fluorescence detector (SCAFUD) was developed for high-throughput genotyping of short tandem repeat polymorphisms (STRPs). Fluorescent dyes are incorporated into relatively short DNA fragments via polymerase chain reaction (PCR) and are separated by electrophoresis in short, wide polyacrylamide gels (144 lanes with well to read distances of 14 cm). Excitation light from an argon laser with primary lines at 488 and 514 nm is introduced into the gel through a fiber optic cable, dichroic mirror, and 40X microscope objective. Emitted fluorescent light is collected confocally through a second fiber. The confocal head is translated across the bottom of the gel at 0.5 Hz. The detection unit utilizes dichroic mirrors and band pass filters to direct light with 10 - 20 nm bandwidths to four photomultiplier tubes (PMTs). PMT signals are independently amplified with variable gain and then sampled at a rate of 2500 points per scan using a computer based A/D board. LabView software (National Instruments) is used for instrument operation. Currently, three fluorescent dyes (Fam, Hex and Rox) are simultaneously detected with peak detection wavelengths of 543, 567, and 613 nm, respectively. The detection limit for fluorescein-labeled primers is about 100 attomoles. Planned SCAFUD upgrades include rearrangement of laser head geometry, use of additional excitation lasers for simultaneous detection of more dyes, and the use of detector arrays instead of individual PMTs. Extensive software has been written for automatic analysis of SCAFUD images. The software enables background subtraction, band identification, multiple- dye signal resolution, lane finding, band sizing and allele calling. Whole genome screens are currently underway to search for loci influencing such complex diseases as diabetes, asthma, and hypertension. Seven production SCAFUDs are currently in operation. Genotyping output for the coming year is projected to be about one million total genotypes (DNA samples X polymorphic markers) at a total cost of
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NASA Astrophysics Data System (ADS)
Toprak, E.; Schnaiter, M.
2013-01-01
In this paper bioaerosol measurements conducted with the Waveband Integrated Bioaerosol Sensor mark 4 (WIBS-4) are presented. The measurements comprise aerosol chamber characterization experiments and a one-year ambient measurement period at a semi-rural site in South Western Germany. This study aims to investigate the sensitivity of WIBS-4 to biological and non-biological aerosols and detection of biological particles in the ambient aerosol. Several types of biological and non-biological aerosol samples, including fungal spores, bacteria, mineral dust, ammonium sulphate, combustion soot, and fluorescent polystyrene spheres, were analyzed by WIBS-4 in the laboratory. The results confirm the sensitivity of the ultraviolet light-induced fluorescence (UV-LIF) method to biological fluorophores and show the good discrimination capabilities of the two excitation wavelengths/detection wavebands method applied in WIBS-4. However, a weak cross-sensitivity to non-biological fluorescent interferers remains and is discussed in this paper. All the laboratory studies have been undertaken in order to prepare WIBS-4 for ambient aerosol measurements. According to the one-year ambient aerosol study, number concentration of fluorescent biological aerosol particles (FBAP) show strong seasonal and diurnal variability. The highest number concentration of FBAP was measured during the summer term and decreased towards the winter period when colder and drier conditions prevail. Diurnal FBAP concentrations start to increase after sunset and reach maximum values during the late night and early morning hours. On the other hand, the total aerosol number concentration was almost always higher during daytime than during nighttime and a sharp decrease after sunset was observed. There was no correlation observed between the FBAP concentration and the meteorological parameters temperature, precipitation, wind direction and wind speed. However, a clear correlation was identified between the FBAP number concentration and the relative humidity. Humidity-controlled release mechanisms of some fungal spore species are discussed as a possible explanation.
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NASA Astrophysics Data System (ADS)
El-Habashi, Ahmed; Duran, Claudia M.; Lovko, Vincent; Tomlinson, Michelle C.; Stumpf, Richard P.; Ahmed, Sam
2017-07-01
We apply a neural network (NN) technique to detect/track Karenia brevis harmful algal blooms (KB HABs) plaguing West Florida shelf (WFS) coasts from Visible-Infrared Imaging Radiometer Suite (VIIRS) satellite observations. Previously KB HABs detection primarily relied on the Moderate Resolution Imaging Spectroradiometer Aqua (MODIS-A) satellite, depending on its remote sensing reflectance signal at the 678-nm chlorophyll fluorescence band (Rrs678) needed for normalized fluorescence height and related red band difference retrieval algorithms. VIIRS, MODIS-A's successor, does not have a 678-nm channel. Instead, our NN uses Rrs at 486-, 551-, and 671-nm VIIRS channels to retrieve phytoplankton absorption at 443 nm (a). The retrieved a images are next filtered by applying limits, defined by (i) low Rrs551-nm backscatter and (ii) a minimum a value associated with KB HABs. The filtered residual images are then converted to show chlorophyll-a concentrations [Chla] and KB cell counts. VIIRS retrievals using our NN and five other retrieval algorithms were compared and evaluated against numerous in situ measurements made over the four-year 2012 to 2016 period, for which VIIRS data are available. These comparisons confirm the viability and higher retrieval accuracies of the NN technique, when combined with the filtering constraints, for effective detection of KB HABs. Analysis of these results as well as sequential satellite observations and recent field measurements underline the importance of short-term temporal variabilities on retrieval accuracies.
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Fluorescein Diacetate Microplate Assay in Cell Viability Detection.
Chen, Xi; Yang, Xiu-Ying; Fang, Lian-Hua; DU, Guan-Hua
2016-12-20
Objective To investigate the application of the fluorescein diacetate (FDA) microplate assay in cell viability detection. Methods Cells were seeded in a 96-well culture plate until detection. After incubated with FDA,the plate was detected by fluorescence microplate analyzer. The effects of FDA incubation duration,concentration,and other factors on the assay's accuracy and stability were assessed. We also compared the results of FDA with methyl thiazolyl(MTT) in terms of cell numbers and H 2 O 2 injury. Results Within 0-30 minutes,the fluorescence-cell number coefficient of FDA assay increased with duration and reached 0.99 in 27-30 minutes. The optimum concentration of final FDA in this study was 10-30 μg/ml. On cell viability detection,the result of FDA method was equivalent to MTT method. As to H 2 O 2 injury assay,the sensitivity of FDA method was superior to MTT on the higher concentration H 2 O 2 treatment due to a relative shorter duration for detection. Conclusion As a stable and reliable method,FDA is feasible for cell variability detection under varied conditions.
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Wen, D.; Qing, L.; Harrison, G.; Golub, E.; Akintoye, S.O.
2010-01-01
Objectives Bisphosphonates commonly used to treat osteoporosis, Paget’s disease, multiple myeloma, hypercalcemia of malignancy and osteolytic lesions of cancer metastasis have been associated with bisphosphonate-associated jaw osteonecrosis (BJON). The underlying pathogenesis of BJON is unclear, but disproportionate bisphosphonate concentration in the jaw has been proposed as one potential etiological factor. This study tested the hypothesis that skeletal biodistribution of intravenous bisphosphonate is anatomic site-dependent in a rat model system. Materials and Methods Fluorescently labeled pamidronate was injected intravenously in athymic rats of equal weights followed by in vivo whole body fluorimetry, ex vivo optical imaging of oral, axial and appendicular bones and ethylenediaminetetraacetic acid bone decalcification to assess hydroxyapatite-bound bisphosphonate. Results Bisphosphonate uptake and bisphosphonate released per unit calcium were similar in oral and appendicular bones but lower than those in axial bones. Hydroxyapatite-bound bisphosphonate liberated by sequential acid decalcification was highest in oral relative to axial and appendicular bones (p < 0.05). Conclusions This study demonstrates regional differences in uptake and release of bisphosphonate from oral, axial and appendicular bones of immune deficient rats. PMID:21122034
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NASA Astrophysics Data System (ADS)
Picard, Christine; Bosco, Marco
2008-01-01
Several soil microorganisms colonizing roots are known to naturally promote the health of plants by controlling a range of plant pathogens, including bacteria, fungi, and nematodes. The use of theses antagonistic microorganisms, recently named plant-probiotics, to control plant-pathogenic fungi is receiving increasing attention, as they may represent a sustainable alternative to chemical pesticides. Many years of research on plant-probiotic microorganisms (PPM) have indicated that fluorescent pseudomonads producing antimicrobial compounds are largely involved in the suppression of the most widespread soilborne pathogens. Phenotype and genotype analysis of plant-probiotic fluorescent pseudomonads (PFP) have shown considerable genetic variation among these types of strains. Such variability plays an important role in the rhizosphere competence and the biocontrol ability of PFP strains. Understanding the mechanisms by which genotypic and phenotypic diversity occurs in natural populations of PFP could be exploited to choose those agricultural practices which best exploit the indigenous PFP populations, or to isolate new plant-probiotic strains for using them as inoculants. A number of different methods have been used to study diversity within PFP populations. Because different resolutions of the existing microbial diversity can be revealed depending on the approach used, this review first describes the most important methods used for the assessment of fluorescent Pseudomonas diversity. Then, we focus on recent data relating how differences in genotypic and phenotypic diversity within PFP communities can be attributed to geographic location, climate, soil type, soil management regime, and interactions with other soil microorganisms and host plants. It becomes evident that plant-related parameters exert the strongest influence on the genotypic and phenotypic variations in PFP populations.
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Using fluorescence to augment the efficacy of photodynamic therapy
NASA Astrophysics Data System (ADS)
Dickey, Dwayne J.; Liu, Weiyang; Naicker, Selvaraj; Woo, Thomas; Moore, Ronald B.; Tulip, John
2006-09-01
Photodynamic Therapy (PDT) is a relatively novel oncological treatment modality, in which a patient is administered a photosensitive drug, called a photosensitizer. After allowing sufficient time for biodistribution, the cancerous area is irradiated with light of the appropriate wavelength, activating the photosensitizer to produce highly reactive singlet oxygen, which produces a highly localized cell kill. The efficacy of PDT is determined by a) the intensity of the light b) the local concentration of the photosensitizer, and c) the availability of oxygen. However, with the clinical application of PDT, the patient is simply administered a body mass dependent quantity of photosensitizer, and then the target area is administered a prescribed amount of radiant energy (joules per cubic centimetre). For treatment of superficial malignancies, PDT has many successes; however, interstitial PDT (PDT of solid, internal malignancies) has inconsistent outcomes mostly due to the inability to predict, calculate or measure the variables that affect PDT: the radiation dose, oxygen concentration, and the photosensitizer concentration. We have developed sophisticated methods to determine the behaviour of light in homogeneous biological tissues. Tissue oxygen levels can be replenished by fractionating the light dose - allowing areas of your target tissue to go through a "dark" cycle during PDT. However, to date, there has not been an accurate method of determining tissue photosensitizer concentrations in-vivo. We are researching the efficacy of a novel hypocrellin derivative, SL-052. Like other photosensitizers available, SL-052 shows strong therapeutic photodynamic activity when irradiated by 635 nm light. Like most photosensitizers, SL-052 exhibits fluorescent activity, but SL-052 also shows strong fluorescent emission at 725nm when excited by 635 nm. The intensity of the fluorescent emission can been correlated with the local concentration of the photosenstizer. However, many clinically available photosensitizers require that fluorescence is excited using a wavelength of light much shorter than the therapeutic wavelength. This characteristic allows us to monitor the availability of the photosensitizer during PDT and to correlate the outcome of PDT to the observed fluorescence. In this paper, we monitor the temporal distribution of SL-052 in the Dunning R3327-AT cell line grown on the flank of a Fisher Copenhangen rats.
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2017-01-01
Förster resonance energy transfer (FRET) measurements from a donor, D, to an acceptor, A, fluorophore are frequently used in vitro and in live cells to reveal information on the structure and dynamics of DA labeled macromolecules. Accurate descriptions of FRET measurements by molecular models are complicated because the fluorophores are usually coupled to the macromolecule via flexible long linkers allowing for diffusional exchange between multiple states with different fluorescence properties caused by distinct environmental quenching, dye mobilities, and variable DA distances. It is often assumed for the analysis of fluorescence intensity decays that DA distances and D quenching are uncorrelated (homogeneous quenching by FRET) and that the exchange between distinct fluorophore states is slow (quasistatic). This allows us to introduce the FRET-induced donor decay, εD(t), a function solely depending on the species fraction distribution of the rate constants of energy transfer by FRET, for a convenient joint analysis of fluorescence decays of FRET and reference samples by integrated graphical and analytical procedures. Additionally, we developed a simulation toolkit to model dye diffusion, fluorescence quenching by the protein surface, and FRET. A benchmark study with simulated fluorescence decays of 500 protein structures demonstrates that the quasistatic homogeneous model works very well and recovers for single conformations the average DA distances with an accuracy of < 2%. For more complex cases, where proteins adopt multiple conformations with significantly different dye environments (heterogeneous case), we introduce a general analysis framework and evaluate its power in resolving heterogeneities in DA distances. The developed fast simulation methods, relying on Brownian dynamics of a coarse-grained dye in its sterically accessible volume, allow us to incorporate structural information in the decay analysis for heterogeneous cases by relating dye states with protein conformations to pave the way for fluorescence and FRET-based dynamic structural biology. Finally, we present theories and simulations to assess the accuracy and precision of steady-state and time-resolved FRET measurements in resolving DA distances on the single-molecule and ensemble level and provide a rigorous framework for estimating approximation, systematic, and statistical errors. PMID:28709377
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NASA Astrophysics Data System (ADS)
Milev, M.; Nikolova, Kr.; Ivanova, Ir.; Dobreva, M.
2015-11-01
25 olive oils were studied- different in origin and ways of extraction, in accordance with 17 physico-chemical parameters as follows: color parameters - a and b, light, fluorescence peaks, pigments - chlorophyll and β-carotene, fatty-acid content. The goals of the current study were: Conducting correlation analysis to find the inner relation between the studied indices; By applying factor analysis with the help of the method of Principal Components (PCA), to reduce the great number of variables into a few factors, which are of main importance for distinguishing the different types of olive oil;Using K-means cluster to compare and group the tested types olive oils based on their similarity. The inner relation between the studied indices was found by applying correlation analysis. A factor analysis using PCA was applied on the basis of the found correlation matrix. Thus the number of the studied indices was reduced to 4 factors, which explained 79.3% from the entire variation. The first one unified the color parameters, β-carotene and the related with oxidative products fluorescence peak - about 520 nm. The second one was determined mainly by the chlorophyll content and related to it fluorescence peak - about 670 nm. The third and the fourth factors were determined by the fatty-acid content of the samples. The third one unified the fatty-acids, which give us the opportunity to distinguish olive oil from the other plant oils - oleic, linoleic and stearin acids. The fourth factor included fatty-acids with relatively much lower content in the studied samples. It is enquired the number of clusters to be determined preliminary in order to apply the K-Cluster analysis. The variant K = 3 was worked out because the types of the olive oil were three. The first cluster unified all salad and pomace olive oils, the second unified the samples of extra virgin oilstaken as controls from producers, which were bought from the trade network. The third cluster unified samples from pomace and extra virgin oils, which distinguish one from another in accordance with their parameters from the natural olive oils, because of presence of plant oils impurities.
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Reducing the background fluorescence in mice receiving fluorophore/inhibitor DNA duplexes.
Liang, Minmin; Liu, Xinrong; Liu, Guozheng; Dou, Shuping; Cheng, Dengfeng; Liu, Yuxia; Rusckowski, Mary; Hnatowich, Donald J
2011-02-07
In principle, a DNA duplex consisting of an antisense fluorophore-conjugated major strand hybridized to a shorter complementary inhibitor-conjugated minor strand should provide fluorescence only in the tumor after intravenous administration if designed to remain intact except in the presence in tumor of its mRNA target. While we have obtained impressive tumor images in mice using this approach, there remains some background fluorescence. In this study, tissue homogenates of selected mouse organs were incubated with a test duplex and the kinetics of duplex dissociation in normal tissues were measured. In this manner we were able to identify the liver as the likely major source responsible for the duplex dissociation providing this fluorescence background. Thereafter liver homogenates were used to screen a series of duplex candidates with variable-length minor strands, and dissociation was measured by gel electrophoresis. The selected fluorophore/inhibitor duplex with improved stability displayed an insignificant (P > 0.05) background fluorescence after administration to SKH-1 normal mice and apparently without affecting target mRNA binding in vitro in cell culture or in vivo in tumor bearing mice.
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Boosted structured additive regression for Escherichia coli fed-batch fermentation modeling.
Melcher, Michael; Scharl, Theresa; Luchner, Markus; Striedner, Gerald; Leisch, Friedrich
2017-02-01
The quality of biopharmaceuticals and patients' safety are of highest priority and there are tremendous efforts to replace empirical production process designs by knowledge-based approaches. Main challenge in this context is that real-time access to process variables related to product quality and quantity is severely limited. To date comprehensive on- and offline monitoring platforms are used to generate process data sets that allow for development of mechanistic and/or data driven models for real-time prediction of these important quantities. Ultimate goal is to implement model based feed-back control loops that facilitate online control of product quality. In this contribution, we explore structured additive regression (STAR) models in combination with boosting as a variable selection tool for modeling the cell dry mass, product concentration, and optical density on the basis of online available process variables and two-dimensional fluorescence spectroscopic data. STAR models are powerful extensions of linear models allowing for inclusion of smooth effects or interactions between predictors. Boosting constructs the final model in a stepwise manner and provides a variable importance measure via predictor selection frequencies. Our results show that the cell dry mass can be modeled with a relative error of about ±3%, the optical density with ±6%, the soluble protein with ±16%, and the insoluble product with an accuracy of ±12%. Biotechnol. Bioeng. 2017;114: 321-334. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.
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Ristow, O; Otto, S; Geiß, C; Kehl, V; Berger, M; Troeltzsch, M; Koerdt, S; Hohlweg-Majert, B; Freudlsperger, C; Pautke, C
2017-02-01
Recent studies have indicated that bone shows auto-fluorescence under an appropriate fluorescence lamp. The aim of this preliminary study was to compare the success rates of the established tetracycline fluorescence-guided bone surgery with auto-fluorescence-guided bone surgery in the treatment of medication-related osteonecrosis of the jaw (MRONJ). Forty patients suffering from MRONJ were referred for surgical treatment and were divided randomly into two groups: auto-fluorescence (n=20) or tetracycline fluorescence (n=20) guided bone surgery. The primary endpoint was treatment success, defined as the absence of exposed bone at 8 weeks after surgery. Secondary outcomes assessed were mucosal integrity, signs of infection, pain, and loss of sensitivity; these were evaluated descriptively at 10 days, 8 weeks, 6 months, and 1 year after surgery. At 8 weeks postoperative, 18/20 patients (90%) in the auto-fluorescence group and 17/20 patients (85%) in the tetracycline fluorescence group showed mucosal integrity (P>0.05). At the last follow-up, 94% in the auto-fluorescence group and 89% in the tetracycline fluorescence group presented complete mucosal coverage with no exposed bone, infection, or pain (P>0.05). There was no significant difference between the two techniques for any of the secondary outcomes (P>0.05). The results of this preliminary study show that auto-fluorescence-guided bone surgery has comparable success rates to the established tetracycline fluorescence-guided bone surgery. Copyright © 2016 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
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NASA Technical Reports Server (NTRS)
Hubler, M.; Souders, J. E.; Shade, E. D.; Hlastala, M. P.; Polissar, N. L.; Glenny, R. W.
1999-01-01
The aim of the study was to validate a nonradioactive method for relative blood flow measurements in severely injured lungs that avoids labor-intensive tissue processing. The use of fluorescent-labeled microspheres was compared with the standard radiolabeled-microsphere method. In seven sheep, lung injury was established by using oleic acid. Five pairs of radio- and fluorescent-labeled microspheres were injected before and after established lung injury. Across all animals, 175 pieces were selected randomly. The radioactivity of each piece was determined by using a scintillation counter. The fluorescent dye was extracted from each piece with a solvent without digestion or filtering. The fluorescence was determined with an automated fluorescent spectrophotometer. Perfusion was calculated for each piece from both the radioactivity and fluorescence and volume normalized. Correlations between flow determined by the two methods were in the range from 0.987 +/- 0.007 (SD) to 0.991 +/- 0.002 (SD) after 9 days of soaking. Thus the fluorescent microsphere technique is a valuable tool for investigating regional perfusion in severely injured lungs and can replace radioactivity.
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NASA Astrophysics Data System (ADS)
Tolhurst, T. J.; Chapman, M. G.; Underwood, A. J.; Cruz, J. J.
2012-09-01
Various methods have been used to remove organisms from sediments to investigate structure and function of faunal assemblages in intertidal habitats. Nevertheless, little is known about how these treatments affect properties of the sediments themselves, although changing these properties may cause changes in the assemblages, independently of other hypotheses being tested. This study assesses the efficacy of defaunation and effect on selected biogeochemical properties of five different methods of defaunating soft muddy sediments in an estuary. The methods were removal and freezing of sediment, removal and oven-heating, freezing in situ with liquid N2, spraying with formalin and spraying with hydrogen peroxide. The first four of these methods have been used in previous studies, whilst the fifth was considered to be a potentially useful defaunator because it does not leave toxic residues. The first two methods required sediment to be brought back to the lab, disrupting the natural structure of the sediment; the last three were done in situ, with much less disturbance. Variables measured to assess effects of the treatments on the sediment were amount of water, grain size, total carbohydrate, suspension index (relative erosion rate), erosion threshold, chlorophyll a and b, colloidal carbohydrate, Fo (minimal fluorescence) and Fv / Fm (photosynthetic yield). There were no significant effects of any treatment on the first four variables. For the others, effects of defaunation varied from treatment to treatment and with time after treatment. Generally, the greatest disturbance was to the microphytobenthos (MPB, measured by chlorophyll and fluorescence) and related variables. For most treatments, recovery was rapid, but the effects of formalin and H2O2 persisted for a few days. Effects on physical properties of the sediment were mostly minor and insignificant. Removal and freezing or heating, however, caused major changes to the sediments because of the disturbances involved. Choosing the appropriate method of defaunation is very important if interpretations are not to be confounded between the effects of defaunation per se and any effects of changes to other biota (such as microphytobenthos) and/or the properties of sediments caused by the method used to defaunate experimental areas.
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Control of fluorescence in quantum emitter and metallic nanoshell hybrids for medical applications
NASA Astrophysics Data System (ADS)
Singh, Mahi R.; Guo, Jiaohan; J. Cid, José M.; De Hoyos Martinez, Jesús E.
2017-03-01
We study the light emission from a quantum emitter and double metallic nanoshell hybrid systems. Quantum emitters act as local sources which transmit their light efficiently due to a double nanoshell near field. The double nanoshell consists of a dielectric core and two outer nanoshells. The first nanoshell is made of a metal, and the second spacer nanoshell is made of a dielectric material or human serum albumin. We have calculated the fluorescence emission for a quantum emitter-double nanoshell hybrid when it is injected in an animal or a human body. Surface plasmon polariton resonances in the double nanoshell are calculated using Maxwell's equations in the quasi-static approximation, and the fluorescence emission is evaluated using the density matrix method in the presence of dipole-dipole interactions. We have compared our theory with two fluorescence experiments in hybrid systems in which the quantum emitter is Indocyanine Green or infrared fluorescent molecules. The outer spacer nanoshell of double metallic nanoshells consists of silica and human serum albumin with variable thicknesses. Our theory explains the enhancement of fluorescence spectra in both experiments. We find that the thickness of the spacer nanoshell layer increases the enhancement when the fluorescence decreases. The enhancement of the fluorescence depends on the type of quantum emitter, spacer layer, and double nanoshell. We also found that the peak of the fluorescence spectrum can be shifted by changing the shape and the size of the nanoshell. The fluorescence spectra can be switched from one peak to two peaks by removing the degeneracy of excitonic states in the quantum emitter. Hence, using these properties, one can use these hybrids as sensing and switching devices for applications in medicine.
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A Fluorescence Lecture Demonstration.
ERIC Educational Resources Information Center
Bozzelli, Joseph W.; Kemp, Marwin
1982-01-01
Describes fluorescence demonstrations related to several aspects of molecular theory and quantitized energy levels. Demonstrations use fluorescent chemical solutions having luminescence properties spanning the visible spectrum. Also describes a demonstration of spontaneous combustion of familiar substances in chlorine. (JN)
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Yang, Jian; Du, Lin; Sun, Jia; Zhang, Zhenbing; Chen, Biwu; Shi, Shuo; Gong, Wei; Song, Shalei
2016-08-22
Paddy rice is one of the most important crops in China, and leaf nitrogen content (LNC) serves as a significant indictor for monitoring crop status. A reliable method is needed for precise and fast quantification of LNC. Laser-induced fluorescence (LIF) technology and reflectance spectra of crops are widely used to monitor leaf biochemical content. However, comparison between the fluorescence and reflectance spectra has been rarely investigated in the monitoring of LNC. In this study, the performance of the fluorescence and reflectance spectra for LNC estimation was discussed based on principal component analysis (PCA) and back-propagation neural network (BPNN). The combination of fluorescence and reflectance spectra was also proposed to monitor paddy rice LNC. The fluorescence and reflectance spectra exhibited a high degree of multi-collinearity. About 95.38%, and 97.76% of the total variance included in the spectra were efficiently extracted by using the first three PCs in PCA. The BPNN was implemented for LNC prediction based on new variables calculated using PCA. The experimental results demonstrated that the fluorescence spectra (R2 = 0.810, 0.804 for 2014 and 2015, respectively) are superior to the reflectance spectra (R2 = 0.721, 0.671 for 2014 and 2015, respectively) for estimating LNC based on the PCA-BPNN model. The proposed combination of fluorescence and reflectance spectra can greatly improve the accuracy of LNC estimation (R2 = 0.912, 0.890 for 2014 and 2015, respectively).
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Häder, Donat-P; Lebert, Michael; Helbling, E Walter
2004-01-23
The filamentous rhodophytes Callithamnion gaudichaudi Agardh and Ceramium sp. were utilized to study the effects of solar radiation (PAR, 400-700 nm, UV-B, 280-315 nm and UV-A, 315-400 nm) on the photosynthetic performance in situ in Patagonia waters (Argentina). A pulse amplitude modulated (PAM) fluorometer was used to determine the fluorescence parameters. The two species grew in different habitats in the eulittoral: Ceramium sp. was found only in rock pools while C. gaudichaudii grew on exposed rocks and fell dry during low tide. Both species differed in their fluorescence parameters and their sensitivity to solar radiation exposure. The photosynthetic quantum yield had its lowest values at noon, but it recovered in the afternoon/evening hours, when irradiances were lower. PAR (irradiance of about 400 W m(-2) at noon) was responsible for most of the decrease in the yield on clear days, especially in Ceramium sp., but UVR (280-400 nm) also accounted for a significant decrease. Fluence rate response curves indicated that both species were adapted to low fluence rates and showed a pronounced non-photochemical quenching at intermediate and higher irradiances. Both species showed a rapid adaptation during measurement of fast induction kinetics but differed significantly in their fluorescence components. All photosynthetic pigments were bleached after 8 h exposure to solar radiation over a full day. Strong absorption in the UV-A range, most likely due to mycosporine-like amino acids, was detected in both strains. The pronounced sensitivity to solar radiation in situ and the recovery capacity of these two filamentous Rhodophyte species, as well as the presence of protective compounds, suggests that these algae have the ability to adapt to the relatively high radiation levels and changes in irradiance found in the Patagonia waters.
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A new relative referencing method for crop monitoring using chlorophyll fluorescence
NASA Technical Reports Server (NTRS)
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.
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Carbon "Quantum" Dots for Fluorescence Labeling of Cells.
Liu, Jia-Hui; Cao, Li; LeCroy, Gregory E; Wang, Ping; Meziani, Mohammed J; Dong, Yiyang; Liu, Yuanfang; Luo, Pengju G; Sun, Ya-Ping
2015-09-02
The specifically synthesized and selected carbon dots of relatively high fluorescence quantum yields were evaluated in their fluorescence labeling of cells. For the cancer cell lines, the cellular uptake of the carbon dots was generally efficient, resulting in the labeling of the cells with bright fluorescence emissions for both one- and two-photon excitations from predominantly the cell membrane and cytoplasm. In the exploration on labeling the live stem cells, the cellular uptake of the carbon dots was relatively less efficient, though fluorescence emissions could still be adequately detected in the labeled cells, with the emissions again predominantly from the cell membrane and cytoplasm. This combined with the observed more efficient internalization of the same carbon dots by the fixed stem cells might suggest some significant selectivity of the stem cells toward surface functionalities of the carbon dots. The needs and possible strategies for more systematic and comparative studies on the fluorescence labeling of different cells, including especially live stem cells, by carbon dots as a new class of brightly fluorescent probes are discussed.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Lindberg, David J.; Wranne, Moa S.; Gilbert Gatty, Mélina
Thioflavin-T (ThT) is one of the most commonly used dyes for amyloid detection, but the origin of its fluorescence enhancement is not fully understood. Herein we have characterised the ThT fluorescence response upon binding to the Aβ(1-40) and Aβ(1-42) variants of the Alzheimer's-related peptide amyloid-β, in order to explore how the photophysical properties of this dye relates to structural and morphological properties of two amyloid fibril types formed by peptides with a high degree of sequence homology. We show that the steady-state ThT fluorescence is 1.7 times more intense with Aβ(1-40) compared to Aβ(1-42) fibrils in concentration matched samples preparedmore » under quiescent conditions. By measuring the excited state lifetime of bound ThT, we also demonstrate a distinct difference between the two fibril isoforms, with Aβ(1-42) fibrils producing a longer ThT fluorescence lifetime compared to Aβ(1-40). The substantial steady-state intensity difference is therefore not explained by differences in fluorescence quantum yield. Further, we find that the ThT fluorescence intensity, but not the fluorescence lifetime, is dependent on the fibril preparation method (quiescent versus agitated conditions). We therefore propose that the fluorescence lifetime is inherent to each isoform and sensitively reports on fibril microstructure in the protofilament whereas the total fluorescence intensity relates to the amount of exposed β-sheet in the mature Aβ fibrils and hence to differences in their morphology. Our results highlight the complexity of ThT fluorescence, and demonstrate its extended use in amyloid fibril characterisation. - Highlights: • ThT emission is more intense with Aβ(1-40) fibrils than with Aβ(1-42) fibrils. • Aβ(1-42) fibrils induce longer ThT fluorescence lifetimes and higher quantum yield. • ThT emission intensity in Aβ fibril samples reports on fibril morphology. • The ThT fluorescence lifetime is a characteristic feature of each Aβ fibril type.« less
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Westerhoff, P.; Anning, D.
2000-01-01
Dissolved (DOC) and total (TOC) organic carbon concentrations and compositions were studied for several river systems in Arizona, USA. DOC composition was characterized by ultraviolet and visible absorption and fluorescence emission (excitation wavelength of 370 nm) spectra characteristics. Ephemeral sites had the highest DOC concentrations, and unregulated perennial sites had lower concentrations than unregulated intermittent sites, regulated sites, and sites downstream from wastewater-treatment plants (p < 0.05). Reservoir outflows and wastewater-treatment plant effluent were higher in DOC concentration (p < 0.05) and exhibited less variability in concentration than inflows to the reservoirs. Specific ultraviolet absorbance values at 254 nm were typically less than 2 m-1(milligram DOC per liter)-1 and lower than values found in most temperate-region rivers, but specific ultraviolet absorbance values increased during runoff events. Fluorescence measurements indicated that DOC in desert streams typically exhibit characteristics of autochthonous sources; however, DOC in unregulated upland rivers and desert streams experienced sudden shifts from autochthonous to allochthonous sources during runoff events. The urban water system (reservoir systems and wastewater-treatment plants) was found to affect temporal variability in DOC concentration and composition. (C) 2000 Elsevier Science B.V.Dissolved (DOC) and total (TOC) organic carbon concentrations and compositions were studied for several river systems in Arizona, USA. DOC composition was characterized by ultraviolet and visible absorption and fluorescence emission (excitation wavelength of 370 nm) spectra characteristics. Ephemeral sites had the highest DOC concentrations, and unregulated perennial sites had lower concentrations than unregulated intermittent sites, regulated sites, and sites downstream from wastewater-treatment plants (p<0.05). Reservoir outflows and wastewater-treatment plant effluent were higher in DOC concentration (p<0.05) and exhibited less variability in concentration than inflows to the reservoirs. Specific ultraviolet absorbance values at 254 nm were typically less than 2 m-1(milligram DOC per liter)-1 and lower than values found in most temperate-region rivers, but specific ultraviolet absorbance values increased during runoff events. Fluorescence measurements indicated that DOC in desert streams typically exhibit characteristics of autochthonous sources; however, DOC in unregulated upland rivers and desert streams experienced sudden shifts from autochthonous to allochthonous sources during runoff events. The urban water system (reservoir systems and wastewater-treatment plants) was found to affect temporal variability in DOC concentration and composition.The influence of urbanization, becoming increasingly common in arid regions, on dissolved organic carbon (DOC) concentrations in surface water resources was studied. DOC concentration and composition, seasonal watershed runoff events, streamflow variations, water management practices, and urban infrastructure in several Arizona watersheds were monitored. Ephemeral sites had the highest DOC levels, and unregulated perennial sites and lower concentrations than unregulated intermittent sites, regulated sites, and sites downstream from wastewater treatment plants. Reservoir outflows and wastewater treatment plant effluent had higher and less variable DOC concentrations than inflows to reservoirs. UV absorbance values, fluorescence measurements, and other indicators suggest that urban water systems (reservoirs and wastewater treatment plants) affect temporal variability in DOC concentration and composition.
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Laser-induced fluorescence studies of premalignant and benign lesions in the female genital tract
NASA Astrophysics Data System (ADS)
af Klinteberg, Claes; Wang, Ingrid; Lindquist, Charlotta; Vaitkuviene, Aurelija; Svanberg, Katarina
1997-12-01
Laser-induced fluorescence (LIF) was studied in vivo from premalignant and benign lesions in the female genital tract, in particular the cervix. The aim of the study was to investigate the possibilities to differentiate cervical intraepithelial neoplasia (CIN) from normal tissue by means of two different fluorescence modalities. Most of the patients were given a low dose (5 mg/kg bw) of (delta) -amino levulinic acid (ALA). The ALA was orally administered 2 - 4 hours prior to the investigation. During this time, the ALA is transformed to the strongly fluorescent protoporphyrin IX (PpIX) via the haem cycle. Excitation light with a wavelength of 405 nm was used to excite the PpIX fluorescence. Excess amounts of PpIX were accumulated preferentially in diseased tissue. However, the variability in the PpIX accumulation from patient to patient was large. By using excitation light at 337 nm, the endogenous fluorophores are more efficiently excited. Therefore, this excitation modality was exploited for studying spectral characteristics of the autofluorescence in different tissue types. The spectra obtained were evaluated by forming fluorescence intensity ratios. The tissue types were grouped according to the histopathological examination. A correlation with the fluorescence ratios was performed. Some problems with the classification remain, mostly due to the difficulties in obtaining histopathologic evaluation of the biopsies at the exact location of the LIF measurements.
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Understanding aquatic microbial processes using EEM's and in-situ fluorescence sensors
NASA Astrophysics Data System (ADS)
Fox, Bethany; Attridge, John; Rushworth, Cathy; Cox, Tim; Anesio, Alexandre; Reynolds, Darren
2015-04-01
The diverse origin of dissolved organic matter (DOM) in aquatic systems is well documented within the literature. Previous literature indicates that coloured dissolved organic matter (CDOM) is, in part, transformed by aquatic microbial processes, and that dissolved organic material derived from a microbial origin exhibits tryptophan-like fluorescence. However, this phenomenon is not fully understood and very little data is available within the current literature. The overall aim of our work is to reveal the microbial-CDOM interactions that give rise to the observed tryptophan-like fluorescence. The work reported here investigates the microbial processes that occur within freshwater aquatic samples, as defined by the biochemical oxygen demand (BOD) test, as a function of the T1 peak (λex/em 280/330-370 nm). A series of standard water samples were prepared using glucose, glutamic acid, BOD dilution water and a bacterial seed (Cole-Parmer BOD microbe capsules). Samples were spiked with CDOM (derived from an environmental water body) and subjected to time resolved BOD analysis and as excitation-emission fluorescence spectroscopy. All EEM spectral data was interrogated using parallel factor analysis (PARAFAC) in an attempt to determine the presence and dominance (relative intensities) of the CDOM-related and T1-related fluorophores within the samples. In-situ fluorescence sensors (Chelsea Technologies Group Ltd.) were also used to monitor the T1 fluorescence peak (UviLux Tryptophan) and the CDOM fluorescence peak (UviLux CDOM) during experiments. Tryptophan-like fluorescence was observed (albeit transient) in both spiked and un-spiked standard water samples. By furthering our understanding of aquatic organic matter fluorescence, its origin, transformation, fate and interaction with aquatic microbiological processes, we aim to inform the design of a new generation in-situ fluorescence sensor for the monitoring of aquatic ecosystem health.
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Wide field fluorescence epi-microscopy behind a scattering medium enabled by speckle correlations
NASA Astrophysics Data System (ADS)
Hofer, Matthias; Soeller, Christian; Brasselet, Sophie; Bertolotti, Jacopo
2018-04-01
Fluorescence microscopy is widely used in biological imaging, however scattering from tissues strongly limits its applicability to a shallow depth. In this work we adapt a methodology inspired from stellar speckle interferometry, and exploit the optical memory effect to enable fluorescence microscopy through a turbid layer. We demonstrate efficient reconstruction of micrometer-size fluorescent objects behind a scattering medium in epi-microscopy, and study the specificities of this imaging modality (magnification, field of view, resolution) as compared to traditional microscopy. Using a modified phase retrieval algorithm to reconstruct fluorescent objects from speckle images, we demonstrate robust reconstructions even in relatively low signal to noise conditions. This modality is particularly appropriate for imaging in biological media, which are known to exhibit relatively large optical memory ranges compatible with tens of micrometers size field of views, and large spectral bandwidths compatible with emission fluorescence spectra of tens of nanometers widths.
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Shrink-induced silica multiscale structures for enhanced fluorescence from DNA microarrays.
Sharma, Himanshu; Wood, Jennifer B; Lin, Sophia; Corn, Robert M; Khine, Michelle
2014-09-23
We describe a manufacturable and scalable method for fabrication of multiscale wrinkled silica (SiO2) structures on shrink-wrap film to enhance fluorescence signals in DNA fluorescence microarrays. We are able to enhance the fluorescence signal of hybridized DNA by more than 120 fold relative to a planar glass slide. Notably, our substrate has improved detection sensitivity (280 pM) relative to planar glass slide (11 nM). Furthermore, this is accompanied by a 30-45 times improvement in the signal-to-noise ratio (SNR). Unlike metal enhanced fluorescence (MEF) based enhancements, this is a far-field and uniform effect based on surface concentration and photophysical effects from the nano- to microscale SiO2 structures. Notably, the photophysical effects contribute an almost 2.5 fold enhancement over the concentration effects alone. Therefore, this simple and robust method offers an efficient technique to enhance the detection capabilities of fluorescence based DNA microarrays.
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Shrink-Induced Silica Multiscale Structures for Enhanced Fluorescence from DNA Microarrays
2015-01-01
We describe a manufacturable and scalable method for fabrication of multiscale wrinkled silica (SiO2) structures on shrink-wrap film to enhance fluorescence signals in DNA fluorescence microarrays. We are able to enhance the fluorescence signal of hybridized DNA by more than 120 fold relative to a planar glass slide. Notably, our substrate has improved detection sensitivity (280 pM) relative to planar glass slide (11 nM). Furthermore, this is accompanied by a 30–45 times improvement in the signal-to-noise ratio (SNR). Unlike metal enhanced fluorescence (MEF) based enhancements, this is a far-field and uniform effect based on surface concentration and photophysical effects from the nano- to microscale SiO2 structures. Notably, the photophysical effects contribute an almost 2.5 fold enhancement over the concentration effects alone. Therefore, this simple and robust method offers an efficient technique to enhance the detection capabilities of fluorescence based DNA microarrays. PMID:25191785
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Use of induced fluorescence measurements to assess aluminum-organic interactions in acidified lakes
NASA Technical Reports Server (NTRS)
Vodacek, A.; Philpot, W. D.
1985-01-01
The application of laser fluorosensing to the tracing of metals in acid lakes is proposed. The effects of the metals on the dissolving organic carbon (DOC) fluorescence is studied using laboratory mixed water samples and natural water samples from Hamilton and Big Moose Lakes in New York. The operation of the laser fluorosensing system employed in the experiment is described. The DOC fluorescence was quenched by Al, Cu, and Fe, and the relation between pH and the quenching rate is examined. The humic substances fluorescence spectra are analyzed to estimate the concentrations of DOC in water and the relative concentration of Al. The interference problems caused by chemical competition between metal ions and ligands, and changes in the background DOC fluorescence are discussed. It is noted that an airborne laser fluorescence is useful for detecting elevated concentrations of metals.
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The Role of Protein Kinase-C in Breast Cancer Invasion and Metastasis
1997-09-01
relatively new reporter molecule that is being increasingly used in a variety of studies is the green fluorescent protein (GFP) from the jellyfish Aequorea ...Calf Serum GFP Green Fluorescent Protein IHC Immunohistochemistry IRB Institutional Review Board MAPK Mitogen Activated Protein Kinase MMP...and in vivo. A relatively new reporter molecule that is being increasingly used in a variety of studies is the green fluorescent protein (GFP) from
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Organic light-emitting device with a phosphor-sensitized fluorescent emission layer
Forrest, Stephen [Ann Arbor, MI; Kanno, Hiroshi [Osaka, JP
2009-08-25
The present invention relates to organic light emitting devices (OLEDs), and more specifically to OLEDS that emit light using a combination of fluorescent emitters and phosphorescent emitters. The emissive region of the devices of the present invention comprise at least one phosphor-sensitized layer which has a combined emission from a phosphorescent emitter and a fluorescent emitter. In preferred embodiments, the invention relates to white-emitting OLEDS (WOLEDs).
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5-ALA based photodynamic management of glioblastoma
NASA Astrophysics Data System (ADS)
Rühm, Adrian; Stepp, Herbert; Beyer, Wolfgang; Hennig, Georg; Pongratz, Thomas; Sroka, Ronald; Schnell, Oliver; Tonn, Jörg-Christian; Kreth, Friedrich-Wilhelm
2014-03-01
Objective: Improvement of the clinical outcome of glioblastoma (GBM) patients by employment of fluorescence and photosensitization on the basis of 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX (PpIX). Methods: In this report the focus is laid on the use of tumor selective PpIX fluorescence for stereotactic biopsy sampling and intra-operative treatment monitoring. In addition, our current concept for treatment planning is presented. For stereotactic interstitial photodynamic therapy (iPDT), radial diffusers were implanted into the contrast enhancing tumor volume. Spectroscopic measurements of laser light transmission and fluorescence between adjacent fibers were performed prior, during and post PDT. Results: PpIX concentrations in primary glioblastoma tissue show high intra- and inter-patient variability, but are usually sufficient for an effective PDT. During individual treatment attempts with 5-ALA based GBM-iPDT, transmission and fluorescence measurements between radial diffusers gave the following results: 1. In some cases, transmission after PDT is considerably reduced compared to the value before PDT, which may be attributable to a depletion of oxygenated hemoglobin and/or diffuse bleeding. 2. PpIX fluorescence is efficiently photobleached during PDT in all cases. Conclusion: iPDT with assessment of PpIX fluorescence and photobleaching is a promising treatment option. Individualization of treatment parameters appears to bear a potential to further improve clinical outcomes.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Obaid, Razib; Buth, Christian; Dakovski, Georgi L.
Here, we measured the fluorescence photon yield of neon upon soft x-ray ionization (~1200 eV) from the x-ray free-electron laser at Linac Coherent Light Source, and demonstrated the usage of a grazing incidence spectrometer with a variable line spacing grating to perform x-ray fluorescence spectroscopy on a gas phase system. Our measurements also allowed us to estimate the focal size of the beam from the theoretical description developed, in terms of the rate equation approximation accounting for photoionization shake off of neutral neon and double auger decay of single core holes.
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NASA Astrophysics Data System (ADS)
Pelevin, V. V.; Zavjalov, P. O.; Belyaev, N. A.; Konovalov, B. V.; Kravchishina, M. D.; Mosharov, S. A.
2017-01-01
The article presents results of underway remote laser sensing of the surface water layer in continuous automatic mode using the UFL-9 fluorescent lidar onboard the R/V Akademik Mstislav Keldysh during cruise 59 in the Kara Sea in 2011. The description of the lidar, the approach to interpreting seawater fluorescence data, and certain methodical aspects of instrument calibration and measurement are presented. Calibration of the lidar is based on laboratory analysis of water samples taken from the sea surface during the cruise. Spatial distribution of chlorophyll a, total organic carbon and suspended matter concentrations in the upper quasi-homogeneous layer are mapped and the characteristic scales of the variability are estimated. Some dependencies between the patchiness of the upper water layer and the atmospheric forcing and freshwater runoff are shown.
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Wu, Cuiqin; Yuan, Dongxing; Liu, Baomin
2006-12-01
An analytical method involving anion exchange high performance liquid chromatographic determination of vitellogenin (Vtg) in fish plasma after postcolumn fluorescence derivatization with o-phthalaldehyde (OPA) was developed. The retention time of Vtg was about 11 min. The reagent variables for derivatization were optimized. The fluorophore was excited at 335 nm and detected at 435 nm. A calibration curve was established ranging from 0.13 to 11.28 microg. The determination limit of Vtg was found to be as low as 0.13 microg. The spiked recovery was 93.6% and interassay variability was less than 4%. The method developed was used to determine Vtg in fish plasma obtained from red sea bream (Pagrosomus major), black porgy (Sparus macrocephalus) and skew band grunt (Hapalogenys nitens), without complicated sample pretreatment. The results confirmed that the method showed advantages of being simple, rapid, reproducible and sensitive.
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Arrigucci, Riccardo; Bushkin, Yuri; Radford, Felix; Lakehal, Karim; Vir, Pooja; Pine, Richard; Martin, December; Sugarman, Jeffrey; Zhao, Yanlin; Yap, George S; Lardizabal, Alfred A; Tyagi, Sanjay; Gennaro, Maria Laura
2017-01-01
We describe a flow-cytometry-based protocol for intracellular mRNA measurements in nonadherent mammalian cells using fluorescence in situ hybridization (FISH) probes. The method, which we call FISH-Flow, allows for high-throughput multiparametric measurements of gene expression, a task that was not feasible with earlier, microscopy-based approaches. The FISH-Flow protocol involves cell fixation, permeabilization and hybridization with a set of fluorescently labeled oligonucleotide probes. In this protocol, surface and intracellular protein markers can also be stained with fluorescently labeled antibodies for simultaneous protein and mRNA measurement. Moreover, a semiautomated, single-tube version of the protocol can be performed with a commercially available cell-wash device that reduces cell loss, operator time and interoperator variability. It takes ~30 h to perform this protocol. An example of FISH-Flow measurements of cytokine mRNA induction by ex vivo stimulation of primed T cells with specific antigens is described. PMID:28518171
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Analysis of quetiapine in human plasma using fluorescence spectroscopy
NASA Astrophysics Data System (ADS)
Mostafa, Islam M.; Omar, Mahmoud A.; Nagy, Dalia M.; Derayea, Sayed M.
2018-05-01
A simple and sensitive spectrofluorimetric method has been development for the assurance of quetiapine fumarate (QTF). The proposed method was utilized for measuring the fluorescence intensity of the yellow fluorescent product at 510 nm (λex 470 nm). The fluorescent product has resulted from the nucleophilic substitution reaction of QTF with 4-chloro-7-nitrobenzofurazane (NBD-Cl) in Mcllvaine buffer (pH 7.0). The diverse variables influencing the development of the reaction product were deliberately changed and optimized. The linear concentration range of the proposed method was of 0.2-2.0 μg ml-1.The limits of detection and quantitation were 0.05 and 0.17 μg ml-1, respectively. The proposed method was applied for the assurance of QTF in its tablets without interference from basic excipients. In addition, the proposed method was used for in vitro analysis of the QTF in spiked human plasma, the percent mean recovery was (n = 3) 98.82 ± 1.484%.
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Zhou, J; Fang, W; Cao, Q; Yang, L; Chang, V W-C; Nazaroff, W W
2017-05-01
Utilizing the ultraviolet light-induced fluorescence (UV-LIF) measurement technique as embodied in the Waveband Integrated Bioaerosol Sensor (WIBS-4A), we evaluated the fluorescent particle emissions associated with human shedding while walking in a chamber. The mean emission rates of supermicron (1-10 μm) fluorescent particles were in the range 6.8-7.5 million particles per person-h (~0.3 mg per person-h) across three participants, for conditions when the relative humidity was 60%-70% and no moisturizer was applied after showering. The fluorescent particles displayed a lognormal distribution with the geometric mean diameter in the range 2.5-4 μm and exhibited asymmetry factors that increased with particle size. Use of moisturizer was associated with changes in number and mass emission rates, size distribution, and particle shape. Emission rates were lower when the relative humidity was reduced, but these differences were not statistically significant. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
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Wang, Shu-tao; Wang, Zhi-fang; Liu, Ming-hua; Wei, Meng; Chen, Dong-ying; Wang, Xing-long
2016-01-01
According to the spectral absorption characteristics of polluting gases and fluorescence characteristics, a time-division multiplexing detection system is designed. Through this system we can detect Methane (CH4) and sulfur dioxide (SO2) by using spectral absorption method and the SO2 can be detected by using UV fluorescence method. The system consists of four parts: a combination of a light source which could be switched, the common optical path, the air chamber and the signal processing section. The spectral absorption characteristics and fluorescence characteristics are measured first. Then the experiment of detecting CH4 and SO2 through spectral absorption method and the experiment of detecting SO2 through UV fluorescence method are conducted, respectively. Through measuring characteristics of spectral absorption and fluorescence, we get excitation wavelengths of SO2 and CH4 measured by spectral absorption method at the absorption peak are 280 nm and 1.64 μm, respectively, and the optimal excitation wavelength of SO2 measured by UV fluorescence method is 220 nm. we acquire the linear relation between the concentration of CH4 and relative intensity and the linear relation between the concentration of SO2 and output voltage after conducting the experiment of spectral absorption method, and the linearity are 98.7%, 99.2% respectively. Through the experiment of UV fluorescence method we acquire that the relation between the concentration of SO2 and the voltage is linear, and the linearity is 99.5%. Research shows that the system is able to be applied to detect the polluted gas by absorption spectrum method and UV fluorescence method. Combing these two measurement methods decreases the costing and the volume, and this system can also be used to measure the other gases. Such system has a certain value of application.
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Study of shock waves and related phenomena motivated by astrophysics
DOE Office of Scientific and Technical Information (OSTI.GOV)
Drake, R. P.; Keiter, P. A.; Kuranz, C. C.
This study discusses the recent research in High-Energy-Density Physics at our Center. Our work in complex hydrodynamics is now focused on mode coupling in the Richtmyer-Meshkov process and on the supersonic Kelvin-Helmholtz instability. These processes are believed to occur in a wide range of astrophysical circumstances. In radiation hydrodynamics, we are studying radiative reverse shocks relevant to cataclysmic variable stars. Our work on magnetized flows seeks to produce magnetized jets and study their interactions. We build the targets for all these experiments, and simulate them using our CRASH code. We also conduct diagnostic research, focused primarily on imaging x-ray spectroscopymore » and its applications to scattering and fluorescence.« less
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Study of shock waves and related phenomena motivated by astrophysics
Drake, R. P.; Keiter, P. A.; Kuranz, C. C.; ...
2016-04-01
This study discusses the recent research in High-Energy-Density Physics at our Center. Our work in complex hydrodynamics is now focused on mode coupling in the Richtmyer-Meshkov process and on the supersonic Kelvin-Helmholtz instability. These processes are believed to occur in a wide range of astrophysical circumstances. In radiation hydrodynamics, we are studying radiative reverse shocks relevant to cataclysmic variable stars. Our work on magnetized flows seeks to produce magnetized jets and study their interactions. We build the targets for all these experiments, and simulate them using our CRASH code. We also conduct diagnostic research, focused primarily on imaging x-ray spectroscopymore » and its applications to scattering and fluorescence.« less
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Joas, Jacques; Vulcain, Emmanuelle; Desvignes, Claire; Morales, Emeline; Léchaudel, Mathieu
2012-04-01
Climacteric fruits are harvested at the green-mature stage and ripen during their marketing cycle. However, growing conditions induce variability into the maturity stage of mangoes at harvest, with an impact on their final quality. Assuming that the physiological age can be correctly evaluated by a criterion based on the variable chlorophyll fluorescence of the skin (F(v)) and that differences in physiological age depend on growing conditions, controlled stress experiments were carried out on mango fruit by manipulating either the leaf/fruit ratio or the light environment. Delays from 9 to 30 days were observed, depending on stress level and harvest stage, to obtain the same F(v) value. For moderate stress, fruit composition after ripening was partially compensated for, with little or no difference in sugar, dry matter, carotenoid and aroma contents. For more pronounced stress, the major metabolites were not particularly affected, but the synthesis capacity of carotenoids and aromas was lower after maturity. The ripening ability of a fruit is acquired on the tree and defines its postharvest changes. Control of the physiological age at harvest can minimise the variability observed under natural conditions and guarantee fruit batches whose postharvest changes will be relatively homogeneous. Copyright © 2011 Society of Chemical Industry.
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Roberts, David W.; Valdés, Pablo A.; Harris, Brent T.; Fontaine, Kathryn M.; Hartov, Alexander; Fan, Xiaoyao; Ji, Songbai; Lollis, S. Scott; Pogue, Brian W.; Leblond, Frederic; Tosteson, Tor D.; Wilson, Brian C.; Paulsen, Keith D.
2010-01-01
Object The aim of this study was to investigate the relationships between intraoperative fluorescence, features on MR imaging, and neuropathological parameters in 11 cases of newly diagnosed glioblastoma multiforme (GBM) treated using protoporphyrin IX (PpIX) fluorescence-guided resection. Methods In 11 patients with a newly diagnosed GBM, δ-aminolevulinic acid (ALA) was administered to enhance endogenous synthesis of the fluorophore PpIX. The patients then underwent fluorescence-guided resection, coregistered with conventional neuronavigational image guidance. Biopsy specimens were collected at different times during surgery and assigned a fluorescence level of 0–3 (0, no fluorescence; 1, low fluorescence; 2, moderate fluorescence; or 3, high fluorescence). Contrast enhancement on MR imaging was quantified using two image metrics: 1) Gd-enhanced signal intensity (GdE) on T1-weighted subtraction MR image volumes, and 2) normalized contrast ratios (nCRs) in T1-weighted, postGd-injection MR image volumes for each biopsy specimen, using the biopsy-specific image-space coordinate transformation provided by the navigation system. Subsequently, each GdE and nCR value was grouped into one of two fluorescence categories, defined by its corresponding biopsy specimen fluorescence assessment as negative fluorescence (fluorescence level 0) or positive fluorescence (fluorescence level 1, 2, or 3). A single neuropathologist analyzed the H & E–stained tissue slides of each biopsy specimen and measured three neuropathological parameters: 1) histopathological score (0–IV); 2) tumor burden score (0–III); and 3) necrotic burden score (0–III). Results Mixed-model analyses with random effects for individuals show a highly statistically significant difference between fluorescing and nonfluorescing tissue in GdE (mean difference 8.33, p = 0.018) and nCRs (mean difference 5.15, p < 0.001). An analysis of association demonstrated a significant relationship between the levels of intraoperative fluorescence and histopathological score (χ2 = 58.8, p < 0.001), between fluorescence levels and tumor burden (χ2 = 42.7, p < 0.001), and between fluorescence levels and necrotic burden (χ2 = 30.9, p < 0.001). The corresponding Spearman rank correlation coefficients were 0.51 (p < 0.001) for fluorescence and histopathological score, and 0.49 (p < 0.001) for fluorescence and tumor burden, suggesting a strongly positive relationship for each of these variables. Conclusions These results demonstrate a significant relationship between contrast enhancement on preoperative MR imaging and observable intraoperative PpIX fluorescence. The finding that preoperative MR image signatures are predictive of intraoperative PpIX fluorescence is of practical importance for identifying candidates for the procedure. Furthermore, this study provides evidence that a strong relationship exists between tumor aggressiveness and the degree of tissue fluorescence that is observable intraoperatively, and that observable fluorescence has an excellent positive predictive value but a low negative predictive value. PMID:20380535
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Hammer, Martin; Königsdörffer, Ekkehart; Liebermann, Christiane; Framme, Carsten; Schuch, Günter; Schweitzer, Dietrich; Strobel, Jürgen
2008-01-01
Post-translational protein modification by lipid peroxidation products or glycation is a feature of aging as well as pathologic processes in postmitotic cells at the ocular fundus exposed to an oxidative environment. The accumulation of modified proteins such as those found in lipofuscin and advanced glycation end products (AGEs) contribute greatly to the fundus auto-fluorescence. The distinct fluorescence spectra of lipofuscin and AGE enable their differentiation in multispectral fundus fluorescence imaging. A dual-centre consecutive case series of 78 pseudo-phacic patients is reported. Digital colour fundus photographs as well as auto-fluorescence images were taken from 33 patients with age related macular degeneration (AMD), 13 patients with diabetic retinopathy (RD), or from 32 cases without pathologic findings (controls). Fluorescence was excited at 475-515 nm or 476-604 nm and recorded in the emission bands 530-675 nm or 675-715 nm, respectively. Fluorescence images excited at 475-515 nm were taken by a colour CCD-camera (colour-fluorescence imaging) enabling the separate recording of green and red fluorescence. The ratio of green versus red fluorescence was calculated within a representative region of each image. The 530-675 nm auto-fluorescence in AMD patients was dominated by the red emission (green vs. red ratio, g/r = 0.861). In comparison, the fluorescence of the diabetics was green-shifted (g/r = 0.946; controls: g/r = 0.869). Atrophic areas (geographic atrophy, laser scars) showed massive hypo-fluorescence in both emission bands. Hyper-fluorescent drusen and exudates, unobtrusive in the colour fundus images as well as in the fluorescence images with emission >667 nm, showed an impressive green-shift in the colour-fluorescence image. Lipofuscin is the dominant fluorophore at long wavelengths (>675 nm or red channel of the colour fluorescence image). In the green spectral region, we found an additional emission of collagen and elastin (optic disc, sclera) as well as deposits in drusen and exudates. The green shift of the auto-fluorescence in RD may be a hint of increased AGE concentrations.
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NASA Technical Reports Server (NTRS)
Daily, J. W.
1978-01-01
Laser induced fluorescence spectroscopy of flames is discussed, and derived uncertainty relations are used to calculate detectability limits due to statistical errors. Interferences due to Rayleigh scattering from molecules as well as Mie scattering and incandescence from particles have been examined for their effect on detectability limits. Fluorescence trapping is studied, and some methods for reducing the effect are considered. Fluorescence trapping places an upper limit on the number density of the fluorescing species that can be measured without signal loss.
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NASA Astrophysics Data System (ADS)
Abbasi, R. U.; Abe, M.; Abu-Zayyad, T.; Allen, M.; Azuma, R.; Barcikowski, E.; Belz, J. W.; Bergman, D. R.; Blake, S. A.; Cady, R.; Cheon, B. G.; Chiba, J.; Chikawa, M.; di Matteo, A.; Fujii, T.; Fujita, K.; Fukushima, M.; Furlich, G.; Goto, T.; Hanlon, W.; Hayashi, M.; Hayashi, Y.; Hayashida, N.; Hibino, K.; Honda, K.; Ikeda, D.; Inoue, N.; Ishii, T.; Ishimori, R.; Ito, H.; Ivanov, D.; Jeong, H. M.; Jeong, S. M.; Jui, C. C. H.; Kadota, K.; Kakimoto, F.; Kalashev, O.; Kasahara, K.; Kawai, H.; Kawakami, S.; Kawana, S.; Kawata, K.; Kido, E.; Kim, H. B.; Kim, J. H.; Kim, J. H.; Kishigami, S.; Kitamura, S.; Kitamura, Y.; Kuzmin, V.; Kuznetsov, M.; Kwon, Y. J.; Lee, K. H.; Lubsandorzhiev, B.; Lundquist, J. P.; Machida, K.; Martens, K.; Matsuyama, T.; Matthews, J. N.; Mayta, R.; Minamino, M.; Mukai, K.; Myers, I.; Nagasawa, K.; Nagataki, S.; Nakamura, R.; Nakamura, T.; Nonaka, T.; Oda, H.; Ogio, S.; Ogura, J.; Ohnishi, M.; Ohoka, H.; Okuda, T.; Omura, Y.; Ono, M.; Onogi, R.; Oshima, A.; Ozawa, S.; Park, I. H.; Pshirkov, M. S.; Rodriguez, D. C.; Rubtsov, G.; Ryu, D.; Sagawa, H.; Sahara, R.; Saito, K.; Saito, Y.; Sakaki, N.; Sakurai, N.; Scott, L. M.; Seki, T.; Sekino, K.; Shah, P. D.; Shibata, F.; Shibata, T.; Shimodaira, H.; Shin, B. K.; Shin, H. S.; Smith, J. D.; Sokolsky, P.; Stokes, B. T.; Stratton, S. R.; Stroman, T. A.; Suzawa, T.; Takagi, Y.; Takahashi, Y.; Takamura, M.; Takeda, M.; Takeishi, R.; Taketa, A.; Takita, M.; Tameda, Y.; Tanaka, H.; Tanaka, K.; Tanaka, M.; Thomas, S. B.; Thomson, G. B.; Tinyakov, P.; Tkachev, I.; Tokuno, H.; Tomida, T.; Troitsky, S.; Tsunesada, Y.; Tsutsumi, K.; Uchihori, Y.; Udo, S.; Urban, F.; Wong, T.; Yamamoto, M.; Yamane, R.; Yamaoka, H.; Yamazaki, K.; Yang, J.; Yashiro, K.; Yoneda, Y.; Yoshida, S.; Yoshii, H.; Zhezher, Y.; Zundel, Z.; Telescope Array Collaboration
2018-05-01
The Telescope Array (TA) observatory utilizes fluorescence detectors and surface detectors (SDs) to observe air showers produced by ultra high energy cosmic rays in Earth’s atmosphere. Cosmic-ray events observed in this way are termed hybrid data. The depth of air shower maximum is related to the mass of the primary particle that generates the shower. This paper reports on shower maxima data collected over 8.5 yr using the Black Rock Mesa and Long Ridge fluorescence detectors in conjunction with the array of SDs. We compare the means and standard deviations of the observed {X}\\max distributions with Monte Carlo {X}\\max distributions of unmixed protons, helium, nitrogen, and iron, all generated using the QGSJet II-04 hadronic model. We also perform an unbinned maximum likelihood test of the observed data, which is subjected to variable systematic shifting of the data {X}\\max distributions to allow us to test the full distributions, and compare them to the Monte Carlo to see which elements are not compatible with the observed data. For all energy bins, QGSJet II-04 protons are found to be compatible with TA hybrid data at the 95% confidence level after some systematic {X}\\max shifting of the data. Three other QGSJet II-04 elements are found to be compatible using the same test procedure in an energy range limited to the highest energies where data statistics are sparse.
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Tamura, Yoji; Hirota, Yuki; Miyata, Shiro; Yamada, Yoshitaka; Tucker, Adam; Kuroiwa, Toshihiko
2012-08-01
The authors assessed the usefulness of intraoperative near-infrared indocyanine green videoangiography (ICG-VA) in the microscopic resection of hemangioblastomas. From January 2009 to February 2012, nine consecutive patients (seven men, two women) who underwent surgery for hemangioblastomas using intraoperative ICG-VA were included in this study. Surgery was performed on four cystic cerebellar lesions with mural nodules, two solid tumors (one in the cerebellar hemisphere and one in the medulla oblongata), one spinal tumor and multiple tumors in two patients with von Hippel-Lindau disease. Of the nine patients, three were treated for recurrent tumor. The ICG-induced fluorescence images of hemangioblastomas with variable presentation were evaluated. All tumors could be completely removed en bloc. Blood flow in the tumor and tumor-related vessels at the brain surface were clearly detected by ICG-VA in all cases, except one recurrent tumor where postoperative adhesive scar tissue obstructed ICG-induced fluorescence resulting in poor delineation of the blood flow patterns and tumor margins. ICG-VA was also helpful for detecting the multiple small mural nodules within the cyst or the tumors buried under thin gliotic neural tissue despite reduced fluorescence. Intraoperative ICG-VA is a safe and easy modality for confirming the vascular flow patterns in hemangioblastomas. In addition, ICG-VA provided useful information for intracystic small lesions or lesions concealed under thin brain tissue in order to accomplish total resection of these tumors.
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Fluorescence spectroscopy for endogenous porphyrins in human facial skin
NASA Astrophysics Data System (ADS)
Seo, I.; Tseng, S. H.; Cula, G. O.; Bargo, P. R.; Kollias, N.
2009-02-01
The activity of certain bacteria in skin is known to correlate to the presence of porphyrins. In particular the presence of coproporphyrin produced by P.acnes inside plugged pores has been correlated to acne vulgaris. Another porphyrin encountered in skin is protoporphyrin IX, which is produced by the body in the pathway for production of heme. In the present work, a fluorescence spectroscopy system was developed to measure the characteristic spectrum and quantify the two types of porphyrins commonly present in human facial skin. The system is comprised of a Xe lamp both for fluorescence excitation and broadband light source for diffuse reflectance measurements. A computer-controlled filter wheel enables acquisition of sequential spectra, first excited by blue light at 405 nm then followed by the broadband light source, at the same location. The diffuse reflectance spectrum was used to correct the fluorescence spectrum due to the presence of skin chromophores, such as blood and melanin. The resulting fluorescence spectra were employed for the quantification of porphyrin concentration in a population of healthy subjects. The results show great variability on the concentration of these porphyrins and further studies are being conducted to correlate them with skin conditions such as inflammation and acne vulgaris.
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Xu, Yujing; Hong, Tingting; Chen, Xueping; Ji, Yibing
2017-05-01
Baseline separation of omeprazole (OME) enantiomers was achieved by affinity capillary electrophoresis (ACE), using human serum albumin (HSA) as the chiral selector. The influence of several experimental variables such as HSA concentration, the type and content of organic modifiers, applied voltage and running buffer concentration on the separation was evaluated. The binding of esomeprazole (S-omeprazole, S-OME) and its R-enantiomer (R-omeprazole, R-OME) to HSA under simulated physiological conditions was studied by ACE and fluorescence spectroscopy which was considered as a reference method. ACE studies demonstrated that the binding constants of the two enantiomers and HSA were 3.18 × 10 3 M -1 and 5.36 × 10 3 M -1 , respectively. The binding properties including the fluorescence quenching mechanisms, binding constants, binding sites and the number of binding sites were obtained by fluorescence spectroscopy. Though the ACE method could not get enough data when compared with the fluorescence spectrum method, the separation and binding studies of chiral drugs could be achieved simultaneously via this method. This study is of great significance for the investigation and clinical application of chiral drugs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Ma, Li Ying; Wang, Huai You; Xie, Hui; Xu, Li Xiao
2004-07-01
The fluorescence property of fluorescein isothiocyanate (FITC) in acid-alkaline medium was studied by spectrofluorimetry. The characteristic of FITC response to hydrogen ion has been examined in acid-alkaline solution. A novel pH chemical sensor was prepared based on the relationship between the relative fluorescence intensity of FITC and pH. The measurement of relative fluorescence intensity was carried out at 362 nm with excitation at 250 nm. The excellent linear relationship was obtained between relative fluorescence intensity and pH in the range of pH 1-5. The linear regression equation of the calibration graph is F = 66.871 + 6.605 pH (F is relative fluorescence intensity), with a correlation coefficient of linear regression of 0.9995. Effects of temperature, concentration of FITC on the response to hydrogen ion had been examined. It was important that this chemical sensor was long lifetime, and the property of response to hydrogen ion was stable for at least 70 days. This pH sensor can be used for measuring pH value in water solution. The accuracy is 0.01 pH unit. The results obtained by the pH sensor agreed with those by the pH meter. Obviously, this pH sensor is potential for determining pH change real time in biological system.
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NASA Astrophysics Data System (ADS)
Ma, Li Ying; Wang, Huai You; Xie, Hui; Xu, Li Xiao
2004-07-01
The fluorescence property of fluorescein isothiocyanate (FITC) in acid-alkaline medium was studied by spectrofluorimetry. The characteristic of FITC response to hydrogen ion has been examined in acid-alkaline solution. A novel pH chemical sensor was prepared based on the relationship between the relative fluorescence intensity of FITC and pH. The measurement of relative fluorescence intensity was carried out at 362 nm with excitation at 250 nm. The excellent linear relationship was obtained between relative fluorescence intensity and pH in the range of pH 1-5. The linear regression equation of the calibration graph is F=66.871+6.605 pH ( F is relative fluorescence intensity), with a correlation coefficient of linear regression of 0.9995. Effects of temperature, concentration of FITC on the response to hydrogen ion had been examined. It was important that this chemical sensor was long lifetime, and the property of response to hydrogen ion was stable for at least 70 days. This pH sensor can be used for measuring pH value in water solution. The accuracy is 0.01 pH unit. The results obtained by the pH sensor agreed with those by the pH meter. Obviously, this pH sensor is potential for determining pH change real time in biological system.
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Replaceable Sensor System for Bioreactor Monitoring
NASA Technical Reports Server (NTRS)
Mayo, Mike; Savoy, Steve; Bruno, John
2006-01-01
A sensor system was proposed that would monitor spaceflight bioreactor parameters. Not only will this technology be invaluable in the space program for which it was developed, it will find applications in medical science and industrial laboratories as well. Using frequency-domain-based fluorescence lifetime technology, the sensor system will be able to detect changes in fluorescence lifetime quenching that results from displacement of fluorophorelabeled receptors bound to target ligands. This device will be used to monitor and regulate bioreactor parameters including glucose, pH, oxygen pressure (pO2), and carbon dioxide pressure (pCO2). Moreover, these biosensor fluorophore receptor-quenching complexes can be designed to further detect and monitor for potential biohazards, bioproducts, or bioimpurities. Biosensors used to detect biological fluid constituents have already been developed that employ a number of strategies, including invasive microelectrodes (e.g., dark electrodes), optical techniques including fluorescence, and membrane permeable systems based on osmotic pressure. Yet the longevity of any of these sensors does not meet the demands of extended use in spacecraft habitat or bioreactor monitoring. It was therefore necessary to develop a sensor platform that could determine not only fluid variables such as glucose concentration, pO2, pCO2, and pH but can also regulate these fluid variables with controlled feedback loop.
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Uyuşur, Burcu; Snee, Preston T.; Li, Chunyan; ...
2016-01-01
Knowledge of the fate and transport of nanoparticles in the subsurface environment is limited, as techniques to monitor and visualize the transport and distribution of nanoparticles in porous media and measure their in situ concentrations are lacking. To address these issues, we have developed a light transmission and fluorescence method to visualize and measure in situ concentrations of quantum dot (QD) nanoparticles in variably saturated environments. Calibration cells filled with sand as porous medium and various known water saturation levels and QD concentrations were prepared. By measuring the intensity of the light transmitted through porous media exposed to fluorescent lightmore » and by measuring the hue of the light emitted by the QDs under UV light exposure, we obtained simultaneously in situ measurements of water saturation and QD nanoparticle concentrations with high spatial and temporal resolutions. Water saturation was directly proportional to the light intensity. A linear relationship was observed between hue-intensity ratio values and QD concentrations for constant water saturation levels. Lastly, the advantages and limitations of the light transmission and fluorescence method as well as its implications for visualizing and measuring in situ concentrations of QDs nanoparticles in the subsurface environment are discussed.« less
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A bright monomeric green fluorescent protein derived from Branchiostoma lanceolatum
Shaner, Nathan C.; Lambert, Gerard G.; Chammas, Andrew; Ni, Yuhui; Cranfill, Paula J.; Baird, Michelle A.; Sell, Brittney R.; Allen, John R.; Day, Richard N.; Israelsson, Maria; Davidson, Michael W.; Wang, Jiwu
2013-01-01
Despite the existence of fluorescent proteins spanning the entire visual spectrum, the bulk of modern imaging experiments continue to rely on variants of the green fluorescent protein derived from Aequorea victoria. Meanwhile, a great deal of recent effort has been devoted to engineering and improving red fluorescent proteins, and relatively little attention has been given to green and yellow variants. Here we report a novel monomeric yellow-green fluorescent protein, mNeonGreen, which is derived from a tetrameric fluorescent protein from the cephalochordate Branchiostoma lanceolatum. This fluorescent protein is the brightest monomeric green or yellow fluorescent protein yet described, performs exceptionally well as a fusion tag for traditional imaging as well as stochastic single-molecule superresolution imaging, and is an excellent FRET acceptor for the newest generation of cyan fluorescent proteins. PMID:23524392
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NASA Astrophysics Data System (ADS)
Zavialov, P. O.; Pelevin, V. V.; Belyaev, N. A.; Izhitskiy, A. S.; Konovalov, B. V.; Krementskiy, V. V.; Goncharenko, I. V.; Osadchiev, A. A.; Soloviev, D. M.; Garcia, C. A. E.; Pereira, E. S.; Sartorato, L.; Moller, O. O.
2018-05-01
We report results of a field survey conducted in the buoyant, sediment-carrying coastal plume generated by the discharge from the Patos Lagoon, the World's largest choked lagoon. The concentration of total suspended matter (TSM) and organic matter (as represented by total organic carbon, TOC) were mapped using an ultraviolet fluorescent LiDAR, which allowed for extensive data coverage (total of 79,387 simultaneous determinations of TSM and TOC) during 3 consecutive days. These observations were accompanied by hydrographic measurements from the ship and at a mooring station. We first describe synoptic variability of the plume, which responded energetically to wind forcing. We then analyze the TSM, TOC and hydrographic data jointly and develop a simple approach to estimate the rates of suspended matter removal from the upper layer due to gravitational settling and turbulent mixing based on relative changes in TSM and TOC concentrations. Four distinct regions within the plume exhibiting different dynamics of suspended and dissolved constituents were identified on this basis.
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Method and apparatus for imaging and documenting fingerprints
Fernandez, Salvador M.
2002-01-01
The invention relates to a method and apparatus for imaging and documenting fingerprints. A fluorescent dye brought in intimate proximity with the lipid residues of a latent fingerprint is caused to fluoresce on exposure to light energy. The resulting fluorescing image may be recorded photographically.
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Khosroshahi, Mohamad E; Rahmani, Mahya
2012-01-01
The aim of this research is to study the normalized fluorescence spectra (intensity variations and area under the fluorescence signal), relative quantum yield, extinction coefficient and intracellular properties of normal and malignant human bone cells. Using Laser-Induced Fluorescence Spectroscopy (LIFS) upon excitation of 405 nm, the comparison of emission spectra of bone cells revealed that fluorescence intensity and the area under the spectra of malignant bone cells was less than that of normal. In addition, the area ratio and shape factor were changed. We obtained two emission bands in spectra of normal cells centered at about 486 and 575 nm and for malignant cells about 482 and 586 nm respectively, which are most likely attributed to NADH and riboflavins. Using fluorescein sodium emission spectrum, the relative quantum yield of bone cells is numerically determined.
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Tian, Kang; Huang, Biao; Xing, Zhe; Hu, Wenyou
2018-04-01
Soil pollution by heavy metals (HMs) has rapidly become a major threat to vegetable security. Nearly all cultivated soils are at risk of metal accumulation, and greenhouse soils are among the most heavily impacted soils. In this study, a rapid assessment of HMs at trace concentrations was conducted via portable X-ray fluorescence (PXRF) spectroscopy in Shouguang, China. Measurements were made via PXRF under in situ, ex situ and sieved conditions and by inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion. The performance of each PXRF measure relative to the ICP-MS method was assessed by linear regression. Redundancy analysis was performed to quantify the proportion of explained variability between the PXRF and ICP-MS data. Evaluation of the possible sources of HMs and their potential risks was then conducted by multivariate analysis. The results showed that the PXRF data were closely correlated with ICP-MS quantification for Cu, Mn and Zn, whereas no significant correlations were found for As, Ni and Pb. The uncertainties of PXRF measurement derived from soil heterogeneity accounted for 20.02% of total variability and those from moisture and particle size accounted for 20.15%. The geo-accumulation index (I geo ) indicated that the greenhouse soils were potentially contaminated by Cu and Zn (I geo > 0), which can be attributed to anthropogenic activities. Overall, PXRF spectroscopy is promising as a rapid and nondestructive in situ technique for assessing the potential risks of HMs at trace concentrations in greenhouse soils.
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Ulstrup, Karin E; Kühl, Michael; Bourne, David G
2007-03-01
Brown band syndrome is a new coral affliction characterized by a local accumulation of yet-unidentified ciliates migrating as a band along the branches of coral colonies. In the current study, morphologically intact zooxanthellae (= Symbiodinium) were observed in great numbers inside the ciliates (>50 dinoflagellates per ciliate). Microscale oxygen measurements and variable chlorophyll a fluorescence analysis along with microscopic observations demonstrated that zooxanthellae within the ciliates are photosynthetically competent and do not become compromised during the progression of the brown band zone. Zooxanthellae showed similar trends in light acclimation in a comparison of rapid light curve and steady-state light curve measures of variable chlorophyll a fluorescence. Extended light exposure of steady-state light curves resulted in higher quantum yields of photosystem II. The brown band tissue exhibited higher photosynthetically active radiation absorptivity, indicating more efficient light absorption due to a higher density of zooxanthellae in the ciliate-dominated zone. This caused relatively higher gross photosynthesis rates in the zone with zooxanthella-containing ciliates compared to healthy coral tissue. The observation of photosynthetically active intracellular zooxanthellae in the ciliates suggests that the latter can benefit from photosynthates produced by ingested zooxanthellae and from photosynthetic oxygen production that alleviates diffusion limitation of oxic respiration in the densely populated brown band tissue. It remains to be shown whether the zooxanthellae form a stable symbiotic association with the ciliate or are engulfed incidentally during grazing on coral tissue and then maintained as active inside the ciliate for a period before being digested and replaced by new zooxanthellae.
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Ulstrup, Karin E.; Kühl, Michael; Bourne, David G.
2007-01-01
Brown band syndrome is a new coral affliction characterized by a local accumulation of yet-unidentified ciliates migrating as a band along the branches of coral colonies. In the current study, morphologically intact zooxanthellae (= Symbiodinium) were observed in great numbers inside the ciliates (>50 dinoflagellates per ciliate). Microscale oxygen measurements and variable chlorophyll a fluorescence analysis along with microscopic observations demonstrated that zooxanthellae within the ciliates are photosynthetically competent and do not become compromised during the progression of the brown band zone. Zooxanthellae showed similar trends in light acclimation in a comparison of rapid light curve and steady-state light curve measures of variable chlorophyll a fluorescence. Extended light exposure of steady-state light curves resulted in higher quantum yields of photosystem II. The brown band tissue exhibited higher photosynthetically active radiation absorptivity, indicating more efficient light absorption due to a higher density of zooxanthellae in the ciliate-dominated zone. This caused relatively higher gross photosynthesis rates in the zone with zooxanthella-containing ciliates compared to healthy coral tissue. The observation of photosynthetically active intracellular zooxanthellae in the ciliates suggests that the latter can benefit from photosynthates produced by ingested zooxanthellae and from photosynthetic oxygen production that alleviates diffusion limitation of oxic respiration in the densely populated brown band tissue. It remains to be shown whether the zooxanthellae form a stable symbiotic association with the ciliate or are engulfed incidentally during grazing on coral tissue and then maintained as active inside the ciliate for a period before being digested and replaced by new zooxanthellae. PMID:17259357
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Lamadrid-Figueroa, Héctor; Téllez-Rojo, Martha M; Angeles, Gustavo; Hernández-Ávila, Mauricio; Hu, Howard
2011-01-01
In-vivo measurement of bone lead by means of K-X-ray fluorescence (KXRF) is the preferred biological marker of chronic exposure to lead. Unfortunately, considerable measurement error associated with KXRF estimations can introduce bias in estimates of the effect of bone lead when this variable is included as the exposure in a regression model. Estimates of uncertainty reported by the KXRF instrument reflect the variance of the measurement error and, although they can be used to correct the measurement error bias, they are seldom used in epidemiological statistical analyzes. Errors-in-variables regression (EIV) allows for correction of bias caused by measurement error in predictor variables, based on the knowledge of the reliability of such variables. The authors propose a way to obtain reliability coefficients for bone lead measurements from uncertainty data reported by the KXRF instrument and compare, by the use of Monte Carlo simulations, results obtained using EIV regression models vs. those obtained by the standard procedures. Results of the simulations show that Ordinary Least Square (OLS) regression models provide severely biased estimates of effect, and that EIV provides nearly unbiased estimates. Although EIV effect estimates are more imprecise, their mean squared error is much smaller than that of OLS estimates. In conclusion, EIV is a better alternative than OLS to estimate the effect of bone lead when measured by KXRF. Copyright © 2010 Elsevier Inc. All rights reserved.
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NASA Astrophysics Data System (ADS)
Zhu, Wen-Zhuo; Zhang, Hong-Hai; Zhang, Jing; Yang, Gui-Peng
2018-04-01
The absorption coefficient and fluorescent components of chromophoric dissolved organic matter (CDOM) in the Bohai Sea (BS), Yellow Sea (YS), and East China Sea (ECS) in spring and autumn were analyzed in this study. Excitation-emission matrices (EEMs) combined with parallel factor analysis (PARAFAC) identified three components, namely, humic-like C1, tyrosine-like C2 and tryptophan-like C3. The seasonal variations in the vertical patterns of the CDOM absorption coefficient (aCDOM(355)) and fluorescent components were influenced by the seasonal water mass except for the terrestrial input. The relationship between aCDOM(355) and dissolved organic matter (DOC) was attributed to their own mixing behavior. The correlation of the fluorescent components with DOC was disturbed by other non-conservative processes during the export of CDOM to the open ocean. The different chemical compositions and origins of DOC and CDOM led to variability in carbon-specific CDOM absorption (a*CDOM(355)) and fluorescent component ratios (ICn/IC1). The relationship between a*CDOM(355) and aCDOM(355) demonstrated that dissolved organic matter (DOM) in the BS, but not in the ECS, highly contributed non-absorbing DOC to the total DOC concentration. The photodegradation of dominant terrestrially derived CDOM in the ECS contributed to the positive relationship between a*CDOM(355) and ICn/IC1. By contrast, the abundant autochthonous CDOM in the YS was negatively correlated with ICn/IC1 in autumn. Our established box models showed that water exchange is a potentially important source of the aromatic components in the BS, YS, and ECS. Hence, the seasonal variations in water exchange might contribute to the variability of CDOM chemical composition in the BS, YS, and ECS, and significantly influence the structure and function of their ecosystems.
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Short time-scale optical pulsations in the night sky background
NASA Technical Reports Server (NTRS)
Bertsch, D. L.; Fisher, A.; Ogelman, H.
1971-01-01
A network of monitoring stations designed to detect large scale fluorescence emission in the atmosphere has been in operation for over two years. The motivation for the search arises from the prediction that an energetic photon burst would be produced in a supernova and this burst, when absorbed in the atmosphere, would produce fluorescence. This paper reports on observations up to February 1971. No supernova-like events have been found, although 4.4 were expected. One class of non-fluorescence events is described that evidence suggests is related to electrical discharge in the atmosphere. Another type of non-fluorescence pulse appears to be related to particle precipitation in the atmosphere.
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Durkovic, Jaroslav; Canová, Ingrid; Lagana, Rastislav; Kucerová, Veronika; Moravcík, Michal; Priwitzer, Tibor; Urban, Josef; Dvorák, Milon; Krajnáková, Jana
2013-02-01
Previous studies have shown that Ophiostoma novo-ulmi, the causative agent of Dutch elm disease (DED), is able to colonize remote areas in infected plants of Ulmus such as the leaf midrib and secondary veins. The objective of this study was to compare the performances in leaf traits between two Dutch elm hybrids 'Groeneveld' and 'Dodoens' which possess a contrasting tolerance to DED. Trait linkages were also tested with leaf mass per area (LMA) and with the reduced Young's modulus of elasticity (MOE) as a result of structural, developmental or functional linkages. Measurements and comparisons were made of leaf growth traits, primary xylem density components, gas exchange variables and chlorophyll a fluorescence yields between mature plants of 'Groeneveld' and 'Dodoens' grown under field conditions. A recently developed atomic force microscopy technique, PeakForce quantitative nanomechanical mapping, was used to reveal nanomechanical properties of the cell walls of tracheary elements such as MOE, adhesion and dissipation. 'Dodoens' had significantly higher values for LMA, leaf tissue thickness variables, tracheary element lumen area (A), relative hydraulic conductivity (RC), gas exchange variables and chlorophyll a fluorescence yields. 'Groeneveld' had stiffer cell walls of tracheary elements, and higher values for water-use efficiency and leaf water potential. Leaves with a large carbon and nutrient investment in LMA tended to have a greater leaf thickness and a higher net photosynthetic rate, but LMA was independent of RC. Significant linkages were also found between the MOE and some vascular traits such as RC, A and the number of tracheary elements per unit area. Strong dissimilarities in leaf trait performances were observed between the examined Dutch elm hybrids. Both hybrids were clearly separated from each other in the multivariate leaf trait space. Leaf growth, vascular and gas exchange traits in the infected plants of 'Dodoens' were unaffected by the DED fungus. 'Dodoens' proved to be a valuable elm germplasm for further breeding strategies.
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Zaidi, Nisar; Bucak, Emre; Okoh, Alexis; Yazici, Pinar; Yigitbas, Hakan; Berber, Eren
2016-06-01
Intraoperative adjuncts for the localization of parathyroid glands in parathyroid surgery are limited. The aim of this study is to assess the usefulness of indocyanine green (ICG) near-infrared (NIR) fluorescent imaging in patients undergoing surgery for primary hyperparathyroidism (PHPT). ICG imaging was performed in 33 patients undergoing parathyroidectomy (PTX). Thyroid and parathyroid ICG uptake were assessed and independently verified on a grading scale. Clinical variables were recorded and analyzed for factors associated with ICG uptake. Of 112 glands identified by naked eye, 104 (92.9%) demonstrated ICG uptake. Concomitant ICG fluorescence was identified in the thyroid in all patients. There was a trend toward increased ICG fluorescence in patients <60 years of age (P = 0.05). A higher degree of fluorescence was seen in patients presenting with pre-operative calcium values >11 mg/dl (P = 0.04) and in those parathyroids larger than 10 mm (P < 0.01). All patients had biochemically proven cure. No patients who underwent subtotal PTX (n = 6) developed postoperative hypoparathyroidism. ICG can reliably localize parathyroid glands during PTX and additionally allow for assessment of parathyroid perfusion in patients undergoing subtotal resection. Concomitant fluorescence of the thyroid gland limits ICG's usefulness in directing the course of PTX. J. Surg. Oncol. 2016;113:771-774. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.
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Effect of arsenic on reflectance spectra and chlorophyll fluorescence of aquatic plants.
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. Copyright © 2014 Elsevier Ltd. All rights reserved.
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NASA Astrophysics Data System (ADS)
Schlosser, Colin; Bodenschatz, Nico; Lam, Sylvia; Lee, Marette; McAlpine, Jessica N.; Miller, Dianne M.; Van Niekerk, Dirk J. T.; Follen, Michele; Guillaud, Martial; MacAulay, Calum E.; Lane, Pierre M.
2016-12-01
Current diagnostic capabilities and limitations of fluorescence endomicroscopy in the cervix are assessed by qualitative and quantitative image analysis. Four cervical tissue types are investigated: normal columnar epithelium, normal and precancerous squamous epithelium, and stromal tissue. This study focuses on the perceived variability within and the subtle differences between the four tissue groups in the context of endomicroscopic in vivo pathology. Conclusions are drawn on the general ability to distinguish and diagnose tissue types, on the need for imaging depth control to enhance differentiation, and on the possible risks for diagnostic misinterpretations.
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Fluorescent optical position sensor
Weiss, Jonathan D.
2005-11-15
A fluorescent optical position sensor and method of operation. A small excitation source side-pumps a localized region of fluorescence at an unknown position along a fluorescent waveguide. As the fluorescent light travels down the waveguide, the intensity of fluorescent light decreases due to absorption. By measuring with one (or two) photodetectors the attenuated intensity of fluorescent light emitted from one (or both) ends of the waveguide, the position of the excitation source relative to the waveguide can be determined by comparing the measured light intensity to a calibrated response curve or mathematical model. Alternatively, excitation light can be pumped into an end of the waveguide, which generates an exponentially-decaying continuous source of fluorescent light along the length of the waveguide. The position of a photodetector oriented to view the side of the waveguide can be uniquely determined by measuring the intensity of the fluorescent light emitted radially at that location.
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Characterization of marine macroalgae by fluorescence signatures
NASA Technical Reports Server (NTRS)
Topinka, J. A.; Bellows, W. Korjeff; Yentsch, C. S.
1990-01-01
The feasibility of distinguishing macroalgal classes by their fluorescence signatures was investigated using narrow-waveband light to excite groups of accessory pigments in brown, red, and green macroalgae and measuring fluorescence emission at 685 nm. Results obtained on 20 marine macroalgae field-collected samples showed that fluorescence excitation signatures were relatively uniform within phylogenetic classes but were substantially different for different classes. It is suggested that it may be possible to characterize the type and the abundance of subtidal macroalgae from low-flying aircraft using existing laser-induced fluorescence methodology.
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An insight into non-emissive excited states in conjugated polymers
NASA Astrophysics Data System (ADS)
Hu, Zhongjian; Willard, Adam P.; Ono, Robert J.; Bielawski, Christopher W.; Rossky, Peter J.; vanden Bout, David A.
2015-09-01
Conjugated polymers in the solid state usually exhibit low fluorescence quantum yields, which limit their applications in many areas such as light-emitting diodes. Despite considerable research efforts, the underlying mechanism still remains controversial and elusive. Here, the nature and properties of excited states in the archetypal polythiophene are investigated via aggregates suspended in solvents with different dielectric constants (ε). In relatively polar solvents (ε>~ 3), the aggregates exhibit a low fluorescence quantum yield (QY) of 2-5%, similar to bulk films, however, in relatively nonpolar solvents (ε<~ 3) they demonstrate much higher fluorescence QY up to 20-30%. A series of mixed quantum-classical atomistic simulations illustrate that dielectric induced stabilization of nonradiative charge-transfer (CT) type states can lead to similar drastic reduction in fluorescence QY as seen experimentally. Fluorescence lifetime measurement reveals that the CT-type states exist as a competitive channel of the formation of emissive exciton-type states.
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Liu, Chen; Tang, Xiangyu; Kim, Jaeshin; Korshin, Gregory V
2015-04-01
This study examined the formation of aldehydes and carboxylic acids in ozonated surface water and municipal wastewater secondary effluent and addressed correlations between the generation of these compounds and concurrent changes of the fluorescence of natural/effluent organic matter (NOM/EfOM) substrates. Ozonation was effective in removing fluorophores in all excitation/emission matrix (EEM) regions, with those operationally assigned to humic- and protein-like species showing relatively higher reactivity than fulvic-like species. Examination of HO exposures and attendant changes of fluorescence-based parameters allows establishing strong linear relationships between formation of the aldehydes and carboxylic acids and the relative changes of integrated fluorescence (ΔIF/IF0). This demonstrates the feasibility of surrogate monitoring of the formation of biodegradable ozonation by-products via online measurements of water/wastewater EEM fluorescence. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Panneton, Bernard; Guillaume, Serge; Roger, Jean-Michel; Samson, Guy
2010-01-01
Precision weeding by spot spraying in real time requires sensors to discriminate between weeds and crop without contact. Among the optical based solutions, the ultraviolet (UV) induced fluorescence of the plants appears as a promising alternative. In a first paper, the feasibility of discriminating between corn hybrids, monocotyledonous, and dicotyledonous weeds was demonstrated on the basis of the complete spectra. Some considerations about the different sources of fluorescence oriented the focus to the blue-green fluorescence (BGF) part, ignoring the chlorophyll fluorescence that is inherently more variable in time. This paper investigates the potential of performing weed/crop discrimination on the basis of several large spectral bands in the BGF area. A partial least squares discriminant analysis (PLS-DA) was performed on a set of 1908 spectra of corn and weed plants over 3 years and various growing conditions. The discrimination between monocotyledonous and dicotyledonous plants based on the blue-green fluorescence yielded robust models (classification error between 1.3 and 4.6% for between-year validation). On the basis of the analysis of the PLS-DA model, two large bands were chosen in the blue-green fluorescence zone (400-425 nm and 425-490 nm). A linear discriminant analysis based on the signal from these two bands also provided very robust inter-year results (classification error from 1.5% to 5.2%). The same selection process was applied to discriminate between monocotyledonous weeds and maize but yielded no robust models (up to 50% inter-year error). Further work will be required to solve this problem and provide a complete UV fluorescence based sensor for weed-maize discrimination.
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2013-09-30
Vision Floc Camera (MVFC), a Sequoia Scientific LISST 100x Type B, an RBR CTD, and two pressure-actuated Niskin bottles. The Niskin bottles were...Eco bb2fl, that measures 3 backscattering at 532 and 650 nm and CDOM fluorescence, a WetLabs WetStar CDOM fluorometer, a Sequoia Scientific flow
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ETS Gene Fusions as Predictive Biomarkers of Resistance to Radiation Therapy for Prostate Cancer
2013-08-01
confocal microscopy to characterize the timing, location, and order of recruitment of the ERG-DNAPK interaction in relation to radiation delivery. In the...DNAPK linked to different fluorescent proteins, and Subtask #5B was to overexpress these constructs in the VCaP cell line and perform real-time...first half of year 3, we generated fusion constructs of ERG to various fluorescent proteins [green fluorescent protein (GFP), yellow fluorescent
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Non-toxic liquid scintillators with high light output based on phenyl-substituted siloxanes
NASA Astrophysics Data System (ADS)
Dalla Palma, M.; Carturan, S. M.; Degerlier, M.; Marchi, T.; Cinausero, M.; Gramegna, F.; Quaranta, A.
2015-04-01
The work describes the development of a new class of liquid scintillators based on polysiloxane liquid compounds. These materials are characterized by low toxicity, chemical inertness, very low volatility and low flammability, allowing their use without concerns even at high temperatures in vacuum. In this view different polysiloxane based liquids have been tested, with variable content and distribution of phenyl lateral substituents and added with suitable dyes, namely 2,5-diphenyloxazole (PPO) and Lumogen Violet (LV). Absorption and fluorescence spectroscopy have been used in order to study the emission feature of the various compounds and to investigate the spectral matching between siloxane solvents and dissolved primary dyes. Scintillation efficiency towards 60Co and 137Cs gamma rays, relative to commercial liquid scintillator (EJ-309), has been measured and the results have been related to the energy transfer and energy migration mechanism from monomer and excimer forming sites in liquid siloxanes.
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NASA Astrophysics Data System (ADS)
Toprak, E.; Schnaiter, M.
2012-07-01
In this paper bioaerosol measurements conducted with the Waveband Integrated Bioaerosol Sensor mark 4 (WIBS-4) are presented. The measurements comprise aerosol chamber characterization experiments and a one-year ambient measurement period at a semi-rural site in South Western Germany. This study aims to investigate the sensitivity of WIBS-4 to biological and non-biological aerosols, performance of WIBS-4 for discrimination of several types of aerosols, and the detection and identification of biological particles in the ambient aerosol. Several types of biological and non-biological aerosol samples including spores, bacteria, pollen, mineral dust, ammonium sulphate, combustion soot, and fluorescent polystyrene spheres were analysed by WIBS-4 in the laboratory. The results confirm the sensitivity of the Ultra Violet Light Induced Fluorescence (UV-LIF) method to biological fluorophores and show the good discrimination capabilities of the two wavelengths excitation/two wavebands detection method applied in WIBS-4. However, a weak cross-sensitivity to non-biological fluorescent interferers remains and is discussed in this paper. All the laboratory studies have been undertaken in order to prepare WIBS-4 for ambient aerosol measurements. According to the one year ambient aerosol study, number concentration of fluorescent biological aerosol particles (FBAP) show strong seasonal and diurnal variability. The highest number concentration of FBAP was measured during the summer term and it decreases towards the winter period when colder and drier conditions are prevailing. Diurnal FBAP concentrations start to increase after sunset and reach maximum values during the late night and early morning hours. On the other hand the total aerosol number concentration was always higher during day time than during night time and a sharp decrease after sunset was observed. There was no correlation observed between the FBAP concentration and the meteorological parameters temperature, precipitation, wind direction and wind speed. However a clear correlation was identified between the FBAP number concentration and the relative humidity. Humidity controlled release mechanisms of some fungal spore species are discussed as a possible explanation.
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NASA Astrophysics Data System (ADS)
Perez-Priego, O.; Guan, J.; Fava, F.; Rossini, M.; Wutzler, T.; Moreno, G.; Carrara, A.; Kolle, O.; Schrumpf, M.; Reichstein, M.; Migliavacca, M.
2014-12-01
Recent studies have shown how human induced N:P imbalances are affecting essential processes (e.g. photosynthesis, plant growth rate) that lead to important changes in ecosystem structure and function. In this regard, the accuracy of the approaches based on remotely-sensed data for monitoring and modeling gross primary production (GPP) relies on the ability of vegetation indices (VIs) to track the dynamics of vegetation physiological and biophysical properties/variables. Promising results have been recently obtained when Chlorophyll-sensitive VIs and Chlorophyll fluorescence are combined with structural indices in the framework of the Monteith's light use efficiency (LUE) model. However, further ground-based experiments are required to validate LUE model performances, and their capability to be generalized under different nutrient availability conditions. In this study, the overall objective was to investigate the sensitivity of VIs to track short- and long-term GPP variations in a Mediterranean grassland under different N and P fertilization treatments. Spectral VIs were acquired manually using high resolution spectrometers (HR4000, OceanOptics, USA) along a phenological cycle. The VIs examined included photochemical reflectance index (PRI), MERIS terrestrial-chlorophyll index (MTCI) and normalized difference vegetation index (NDVI). Solar-induced chlorophyll fluorescence calculated at the oxygen absorption band O2-A (F760) using spectral fitting methods was also used. Simultaneously, measurements of GPP and environmental variables were conducted using a transient-state canopy chamber. Overall, GPP, F760 and VIs showed a clear seasonal time-trend in all treatments, which was driven by the phenological development of the grassland. Results showed significant differences (p<0.05) in midday GPP values between N and without N addition plots, in particular at the peak of the growing season during the flowering stage and at the end of the season during senescence. While NDVI did not show any significant difference between treatments, VIs sensitive to pigment variations and physiology (PRI, MTCI) and F760 behaved as GPP. Model performance test indicated that VIs related to physiology and fluorescence are key to account for nutrient availability in LUE models and to better predict GPP.
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Granat, Fanny; Geffré, Anne; Bourgès-Abella, Nathalie; Braun, Jean-Pierre; Trumel, Catherine
2013-06-01
In veterinary medicine a complete blood cell count (CBC) cannot always be performed within 24 h as usually recommended, particularly for specimens shipped to a reference laboratory. This raises the question of the stability of the variables, especially in ethylenediamine tetra-acetic acid (EDTA) feline blood specimens, known to be prone to in vitro platelet aggregation. Citrate, theophylline, adenosine and dipyridamole (CTAD) has been reported to limit platelet aggregation in feline blood specimens. The aim of this study was to measure the stability of the haematological variables and the platelet aggregation score in EDTA and EDTA plus CTAD (EDCT) feline blood specimens during 48 h of storage at room temperature. Forty-six feline EDTA and EDCT blood specimens were analysed with a Sysmex XT-2000iV analyser, and the platelet count and score of platelet aggregation were estimated immediately and after 24 and 48 h of storage. A significant increase in mean corpuscular volume, haematocrit, reticulocyte and eosinophil counts, and a significant decrease in mean corpuscular haemoglobin concentration and monocyte count were observed. Haemoglobin, mean corpuscular haemoglobin, and red blood cell, white blood cell, neutrophil and lymphocyte counts remained stable. Changes in reticulocyte indexes with time (low fluorescence ratio, medium fluorescence ratio, high fluorescence ratio and immature reticulocyte fraction) were not significant. Changes were generally more pronounced in EDTA than in EDCT. Platelet aggregation decreased markedly in initially highly aggregated EDTA specimens, and increased slightly in initially non- or mildly-aggregated EDTA or EDCT specimens. Platelet counts increased and decreased, or remained stable, respectively. CTAD can reduce storage-induced changes of the haematological variables in feline samples, thus improving the reliability of a CBC and limiting clinical misinterpretations.
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Gittins, John R; D'Angelo, Cecilia; Oswald, Franz; Edwards, Richard J; Wiedenmann, Jörg
2015-01-01
The genomic framework that enables corals to adjust to unfavourable conditions is crucial for coral reef survival in a rapidly changing climate. We have explored the striking intraspecific variability in the expression of coral pigments from the green fluorescent protein (GFP) family to elucidate the genomic basis for the plasticity of stress responses among reef corals. We show that multicopy genes can greatly increase the dynamic range over which corals can modulate transcript levels in response to the light environment. Using the red fluorescent protein amilFP597 in the coral Acropora millepora as a model, we demonstrate that its expression increases with light intensity, but both the minimal and maximal gene transcript levels vary markedly among colour morphs. The pigment concentration in the tissue of different morphs is strongly correlated with the number of gene copies with a particular promoter type. These findings indicate that colour polymorphism in reef corals can be caused by the environmentally regulated expression of multicopy genes. High-level expression of amilFP597 is correlated with reduced photodamage of zooxanthellae under acute light stress, supporting a photoprotective function of this pigment. The cluster of light-regulated pigment genes can enable corals to invest either in expensive high-level pigmentation, offering benefits under light stress, or to rely on low tissue pigment concentrations and use the conserved resources for other purposes, which is preferable in less light-exposed environments. The genomic framework described here allows corals to pursue different strategies to succeed in habitats with highly variable light stress levels. In summary, our results suggest that the intraspecific plasticity of reef corals' stress responses is larger than previously thought. © 2014 The Authors Molecular Ecology Published by John Wiley & Sons Ltd.
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Predina, Jarrod D.; Newton, Andrew D.; Xia, Leilei; Corbett, Christopher; Connolly, Courtney; Shin, Michael; Sulyok, Lydia Frezel; Litzky, Leslie; Deshpande, Charuhas; Nie, Shuming; Kularatne, Sumith A.; Low, Philip S.; Singhal, Sunil
2018-01-01
Background Clinical applicability of folate receptor-targeted intraoperative molecular imaging (FR-IMI) has been established for surgically resectable pulmonary adenocarcinoma. A role for FR-IMI in other lung cancer histologies has not been studied. In this study, we evaluate feasibility of FR-IMI in patients undergoing pulmonary resection for squamous cell carcinomas (SCCs). Methods In a human clinical trial (NCT02602119), twelve subjects with pulmonary SCCs underwent FR-IMI with a near-infrared contrast agent that targets the folate receptor-α (FRα), OTL38. Near-infrared signal from tumors and benign lung was quantified to calculate tumor-to-background ratios (TBR). Folate receptor-alpha expression was characterized, and histopathologic correlative analyses were performed to evaluate patterns of OTL38 accumulation. An exploratory analysis was performed to determine patient and histopathologic variables that predict tumor fluorescence. Results 9 of 13 SCCs (in 9 of 12 of subjects) displayed intraoperative fluorescence upon NIR evaluation (median TBR, 3.9). OTL38 accumulated within SCCs in a FRα-dependent manner. FR-IMI was reliable in localizing nodules as small as 1.1 cm, and prevented conversion to thoracotomy for nodule localization in three subjects. Upon evaluation of patient and histopathologic variables, in situ fluorescence was associated with distance from the pleural surface, and was independent of alternative variables including tumor size and metabolic activity. Conclusions This work demonstrates that FR-IMI is potentially feasible in 70% of SCC patients, and that molecular imaging can improve localization during minimally invasive pulmonary resection. These findings complement previous data demonstrating that ∼98% of pulmonary adenocarcinomas are localized during FR-IMI and suggest broad applicability for NSCLC patients undergoing resection. PMID:29568374
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NASA Technical Reports Server (NTRS)
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.
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Improved two-photon imaging of living neurons in brain tissue through temporal gating
Gautam, Vini; Drury, Jack; Choy, Julian M. C.; Stricker, Christian; Bachor, Hans-A.; Daria, Vincent R.
2015-01-01
We optimize two-photon imaging of living neurons in brain tissue by temporally gating an incident laser to reduce the photon flux while optimizing the maximum fluorescence signal from the acquired images. Temporal gating produces a bunch of ~10 femtosecond pulses and the fluorescence signal is improved by increasing the bunch-pulse energy. Gating is achieved using an acousto-optic modulator with a variable gating frequency determined as integral multiples of the imaging sampling frequency. We hypothesize that reducing the photon flux minimizes the photo-damage to the cells. Our results, however, show that despite producing a high fluorescence signal, cell viability is compromised when the gating and sampling frequencies are equal (or effectively one bunch-pulse per pixel). We found an optimum gating frequency range that maintains the viability of the cells while preserving a pre-set fluorescence signal of the acquired two-photon images. The neurons are imaged while under whole-cell patch, and the cell viability is monitored as a change in the membrane’s input resistance. PMID:26504651
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Multiscale Spectroscopy of Diffusing Molecules in Crowded Environments
NASA Astrophysics Data System (ADS)
Heikal, Ahmed A.
2015-06-01
Living cells are known to be crowded with organelles, biomembranes, and macromolecules such as proteins, DNA, RNA, and actin filaments. It is believed that such macromolecular crowding affect biomolecular diffusion, protein-protein and protein-substrate interaction, and protein folding. In this contribution, I will discuss our recent results on rotational and translational diffusion of small and large molecules in crowded environments using time-resolved anisotropy and fluorescence correlation spectroscopy methods. In these studies, rhodamine green and enhanced green fluorescent protein are used as fluorescent probes diffusing in buffers enriched with biomimetic crowding agents such as Ficoll-70, bovine serum albumin (BSA), and ovalbumin. Controlled experiments on pure and glycerol-rich buffers were carried out as environments with variable, homogeneous viscosity. Our results indicate that the microviscosity differs from the corresponding bulk viscosity, depending on the nature of crowding agents (i.e., proteins versus polymers), the concentration of crowding agents and spatio-temporal scaling of our experimental approach. Our findings provide a foundation for fluorescence-based studies of diffusion and binding of biomolecules in the crowded milieu of living cells.
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A programmable light engine for quantitative single molecule TIRF and HILO imaging.
van 't Hoff, Marcel; de Sars, Vincent; Oheim, Martin
2008-10-27
We report on a simple yet powerful implementation of objective-type total internal reflection fluorescence (TIRF) and highly inclined and laminated optical sheet (HILO, a type of dark-field) illumination. Instead of focusing the illuminating laser beam to a single spot close to the edge of the microscope objective, we are scanning during the acquisition of a fluorescence image the focused spot in a circular orbit, thereby illuminating the sample from various directions. We measure parameters relevant for quantitative image analysis during fluorescence image acquisition by capturing an image of the excitation light distribution in an equivalent objective backfocal plane (BFP). Operating at scan rates above 1 MHz, our programmable light engine allows directional averaging by circular spinning the spot even for sub-millisecond exposure times. We show that restoring the symmetry of TIRF/HILO illumination reduces scattering and produces an evenly lit field-of-view that affords on-line analysis of evanescnt-field excited fluorescence without pre-processing. Utilizing crossed acousto-optical deflectors, our device generates arbitrary intensity profiles in BFP, permitting variable-angle, multi-color illumination, or objective lenses to be rapidly exchanged.
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Calibration of a tunable excimer laser using the optogalvanic effect
NASA Technical Reports Server (NTRS)
Abbitt, John D.
1991-01-01
A device for the calibration of a tunable excimer laser is currently under development. The laser provides UV radiation at three principal wavelengths, 193, 248, and 308 nm and is tunable over a range of 1 nm at each of these wavelengths. The laser is used as a non-intrusive optical probe to excite electronic transitions, and thereby induce fluorescence, of the principle molecules or atoms of interest in supersonic flowfields, both reacting and nonreacting. The fluorescence resulting from the excitation is observed with an intensified camera. Over the range of tunability at the three wavelengths are a number of transitions that can be observed. The intensity of the fluorescence depends in part on the local temperature and density. The nature of this thermodynamic dependence is variable among transitions; thus, identification of the transition under observation is required. The specific transition excited corresponds directly to the wavelength of the radiation. The present technique used for transition identification consists of scanning the laser across the range of tunability and observing the fluorescence resulting from various molecular transitions.
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Fluorescence Spectroscopy and Chemometric Modeling for Bioprocess Monitoring
Faassen, Saskia M.; Hitzmann, Bernd
2015-01-01
On-line sensors for the detection of crucial process parameters are desirable for the monitoring, control and automation of processes in the biotechnology, food and pharma industry. Fluorescence spectroscopy as a highly developed and non-invasive technique that enables the on-line measurements of substrate and product concentrations or the identification of characteristic process states. During a cultivation process significant changes occur in the fluorescence spectra. By means of chemometric modeling, prediction models can be calculated and applied for process supervision and control to provide increased quality and the productivity of bioprocesses. A range of applications for different microorganisms and analytes has been proposed during the last years. This contribution provides an overview of different analysis methods for the measured fluorescence spectra and the model-building chemometric methods used for various microbial cultivations. Most of these processes are observed using the BioView® Sensor, thanks to its robustness and insensitivity to adverse process conditions. Beyond that, the PLS-method is the most frequently used chemometric method for the calculation of process models and prediction of process variables. PMID:25942644
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Recognition of edible oil by using BP neural network and laser induced fluorescence spectrum
NASA Astrophysics Data System (ADS)
Mu, Tao-tao; Chen, Si-ying; Zhang, Yin-chao; Guo, Pan; Chen, He; Zhang, Hong-yan; Liu, Xiao-hua; Wang, Yuan; Bu, Zhi-chao
2013-09-01
In order to accomplish recognition of the different edible oil we set up a laser induced fluorescence spectrum system in the laboratory based on Laser induced fluorescence spectrum technology, and then collect the fluorescence spectrum of different edible oil by using that system. Based on this, we set up a fluorescence spectrum database of different cooking oil. It is clear that there are three main peak position of different edible oil from fluorescence spectrum chart. Although the peak positions of all cooking oil were almost the same, the relative intensity of different edible oils was totally different. So it could easily accomplish that oil recognition could take advantage of the difference of relative intensity. Feature invariants were extracted from the spectrum data, which were chosen from the fluorescence spectrum database randomly, before distinguishing different cooking oil. Then back propagation (BP) neural network was established and trained by the chosen data from the spectrum database. On that basis real experiment data was identified by BP neural network. It was found that the overall recognition rate could reach as high as 83.2%. Experiments showed that the laser induced fluorescence spectrum of different cooking oil was very different from each other, which could be used to accomplish the oil recognition. Laser induced fluorescence spectrum technology, combined BP neural network，was fast, high sensitivity, non-contact, and high recognition rate. It could become a new technique to accomplish the edible oil recognition and quality detection.
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Xie, Zhiwei; Kim, Jimin P; Cai, Qing; Zhang, Yi; Guo, Jinshan; Dhami, Ranjodh S; Li, Li; Kong, Bin; Su, Yixue; Schug, Kevin A; Yang, Jian
2017-03-01
Novel citric acid based photoluminescent dyes and biodegradable polymers are synthesized via a facile "one-pot" reaction. A comprehensive understanding of the fluorescence mechanisms of the resulting citric acid-based fluorophores is reported. Two distinct types of fluorophores are identified: a thiozolopyridine family with high quantum yield, long lifetime, and exceptional photostability, and a dioxopyridine family with relatively lower quantum yield, multiple lifetimes, and solvent-dependent band shifting behavior. Applications in molecular labeling and cell imaging were demonstrated. The above discoveries contribute to the field of fluorescence chemistry and have laid a solid foundation for further development of new fluorophores and materials that show promise in a diversity of fluorescence-based applications. Photoluminescent materials are pivotal for fluorescence based imaging, labeling and sensing applications. Understanding their fluorescence mechanism is challenging and imperative. We develop a new class of citric acid-derived fluorescent materials in forms of polymers and small molecular dyes by a one-step solvent free reaction. We discovered two different classes of citric acid-derived fluorophores. A two-ring thiozolopyridine structure demonstrates strong fluorescence and exceptional resistance to photo-bleaching. A one-ring dioxopyridine exhibits relative weak fluorescence but with intriguing excitation and solvent-dependent emission wavelength shifting. Our methodology of synthesizing citric acid-derived fluorophores and the understanding on their luminescence are instrumental to the design and production of a large number of new photoluminescent materials for biological and biomedical applications. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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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. Copyright © 2014 Elsevier B.V. All rights reserved.
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Singh, Shatrughan; D'Sa, Eurico; Swenson, Erick
2010-01-01
Absorption and fluorescence properties of chromophoric dissolved organic matter (CDOM) along a 124 km transect in the Barataria Basin, a large estuary located in Louisiana, USA, were investigated during high and low flow periods of the Mississippi River in the spring and winter of 2008-2009. Mean CDOM absorption at 355 nm from the marine to the freshwater end member stations ranged from (3.25 +/- 0.56) to (20.76 +/- 2.43) m(-1) for the three month high flow period whereas it varied from (1.48 +/- 1.08) to (25.45 +/- 7.03) m(-1) for the same stations during low flow period. Corresponding salinity values at these stations indicated the influence of river and shelf exchanges in the lower basin and precipitation and runoff in the upper basin. An inverse relationship of CDOM absorbance and fluorescence with salinity observed in the basin could be a useful indicator of salinity. CDOM fluorescence also varied over a large range showing an approximately 8 to 12-fold increase between the marine and freshwater end members for the two flow seasons. Excitation-emission matrix spectral plots indicated the presence of various fluorescence components with highest being the A-peak, lowest the T-peak, and the C and M-peaks showing similar trends along the transect. During low flow season the A/C ratio were well correlated with station locations indicating increased terrestrial influence towards the upper basin. CDOM absorption and fluorescence at 355 nm were highly correlated and independent of CDOM sources suggesting that fluorescence could be used to characterize CDOM in the basin.
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NASA Astrophysics Data System (ADS)
DSouza, Alisha V.; Flynn, Brendan P.; Gunn, Jason R.; Samkoe, Kimberley S.; Anand, Sanjay; Maytin, Edward V.; Hasan, Tayyaba; Pogue, Brian W.
2014-03-01
Treatment monitoring of Aminolevunilic-acid (ALA) - Photodynamic Therapy (PDT) of basal-cell carcinoma (BCC) calls for superficial and subsurface imaging techniques. While superficial imagers exist for this purpose, their ability to assess PpIX levels in thick lesions is poor; additionally few treatment centers have the capability to measure ALA-induced PpIX production. An area of active research is to improve treatments to deeper and nodular BCCs, because treatment is least effective in these. The goal of this work was to understand the logistics and technical capabilities to quantify PpIX at depths over 1mm, using a novel hybrid ultrasound-guided, fiber-based fluorescence molecular spectroscopictomography system. This system utilizes a 633nm excitation laser and detection using filtered spectrometers. Source and detection fibers are collinear so that their imaging plane matches that of ultrasound transducer. Validation with phantoms and tumor-simulating fluorescent inclusions in mice showed sensitivity to fluorophore concentrations as low as 0.025μg/ml at 4mm depth from surface, as presented in previous years. Image-guided quantification of ALA-induced PpIX production was completed in subcutaneous xenograft epidermoid cancer tumor model A431 in nude mice. A total of 32 animals were imaged in-vivo, using several time points, including pre-ALA, 4-hours post-ALA, and 24-hours post-ALA administration. On average, PpIX production in tumors increased by over 10-fold, 4-hours post-ALA. Statistical analysis of PpIX fluorescence showed significant difference among all groups; p<0.05. Results were validated by exvivo imaging of resected tumors. Details of imaging, analysis and results will be presented to illustrate variability and the potential for imaging these values at depth.
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"Open-Box" Approach to Measuring Fluorescence Quenching Using an iPad Screen and Digital SLR Camera
ERIC Educational Resources Information Center
Koenig, Michael H.; Yi, Eun P.; Sandridge, Matthew J.; Mathew, Alexander S.; Demas, James N.
2015-01-01
Fluorescence quenching is an analytical technique and a common undergraduate laboratory exercise. Unfortunately, a typical quenching experiment requires the use of an expensive fluorometer that measures the relative fluorescence intensity of a single sample in a closed compartment unseen by the experimenter. To overcome these shortcomings, we…
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NASA Astrophysics Data System (ADS)
Pompa, P. P.; Cingolani, R.; Rinaldi, R.
2003-07-01
In this paper, we present a deconvolution method aimed at spectrally resolving the broad fluorescence spectra of proteins, namely, of the enzyme bovine liver glutamate dehydrogenase (GDH). The analytical procedure is based on the deconvolution of the emission spectra into three distinct Gaussian fluorescing bands Gj. The relative changes of the Gj parameters are directly related to the conformational changes of the enzyme, and provide interesting information about the fluorescence dynamics of the individual emitting contributions. Our deconvolution method results in an excellent fitting of all the spectra obtained with GDH in a number of experimental conditions (various conformational states of the protein) and describes very well the dynamics of a variety of phenomena, such as the dependence of hexamers association on protein concentration, the dynamics of thermal denaturation, and the interaction process between the enzyme and external quenchers. The investigation was carried out by means of different optical experiments, i.e., native enzyme fluorescence, thermal-induced unfolding, and fluorescence quenching studies, utilizing both the analysis of the “average” behavior of the enzyme and the proposed deconvolution approach.
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The major-element composition of Mercury's surface from MESSENGER X-ray spectrometry.
Nittler, Larry R; Starr, Richard D; Weider, Shoshana Z; McCoy, Timothy J; Boynton, William V; Ebel, Denton S; Ernst, Carolyn M; Evans, Larry G; Goldsten, John O; Hamara, David K; Lawrence, David J; McNutt, Ralph L; Schlemm, Charles E; Solomon, Sean C; Sprague, Ann L
2011-09-30
X-ray fluorescence spectra obtained by the MESSENGER spacecraft orbiting Mercury indicate that the planet's surface differs in composition from those of other terrestrial planets. Relatively high Mg/Si and low Al/Si and Ca/Si ratios rule out a lunarlike feldspar-rich crust. The sulfur abundance is at least 10 times higher than that of the silicate portion of Earth or the Moon, and this observation, together with a low surface Fe abundance, supports the view that Mercury formed from highly reduced precursor materials, perhaps akin to enstatite chondrite meteorites or anhydrous cometary dust particles. Low Fe and Ti abundances do not support the proposal that opaque oxides of these elements contribute substantially to Mercury's low and variable surface reflectance.
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Tereshchenkov, A G; Shishkina, A V; Karpenko, V V; Chertkov, V A; Konevega, A L; Kasatsky, P S; Bogdanov, A A; Sumbatyan, N V
2016-10-01
Novel fluorescent derivatives of macrolide antibiotics related to tylosin bearing rhodamine, fluorescein, Alexa Fluor 488, BODIPY FL, and nitrobenzoxadiazole (NBD) residues were synthesized. The formation of complexes of these compounds with 70S E. coli ribosomes was studied by measuring the fluorescence polarization depending on the ribosome amount at constant concentration of the fluorescent substance. With the synthesized fluorescent tylosin derivatives, the dissociation constants for ribosome complexes with several known antibiotics and macrolide analogs previously obtained were determined. It was found that the fluorescent tylosin derivatives containing BODIPY FL and NBD groups could be used to screen the binding of novel antibiotics to bacterial ribosomes in the macrolide-binding site.
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Promoter architecture dictates cell-to-cell variability in gene expression.
Jones, Daniel L; Brewster, Robert C; Phillips, Rob
2014-12-19
Variability in gene expression among genetically identical cells has emerged as a central preoccupation in the study of gene regulation; however, a divide exists between the predictions of molecular models of prokaryotic transcriptional regulation and genome-wide experimental studies suggesting that this variability is indifferent to the underlying regulatory architecture. We constructed a set of promoters in Escherichia coli in which promoter strength, transcription factor binding strength, and transcription factor copy numbers are systematically varied, and used messenger RNA (mRNA) fluorescence in situ hybridization to observe how these changes affected variability in gene expression. Our parameter-free models predicted the observed variability; hence, the molecular details of transcription dictate variability in mRNA expression, and transcriptional noise is specifically tunable and thus represents an evolutionarily accessible phenotypic parameter. Copyright © 2014, American Association for the Advancement of Science.
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NASA Technical Reports Server (NTRS)
Houston, W. R.; Stephenson, D. G.; Measures, R. M.
1975-01-01
A laboratory investigation has been conducted to evaluate the detection and identification capabilities of laser induced fluorescence as a remote sensing technique for the marine environment. The relative merits of fluorescence parameters including emission and excitation profiles, intensity and lifetime measurements are discussed in relation to the identification of specific targets of the marine environment including crude oils, refined petroleum products, fish oils and algae. Temporal profiles displaying the variation of lifetime with emission wavelength have proven to add a new dimension of specificity and simplicity to the technique.
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Toeppen, John S.
1994-10-04
A fluorescent fiber (13) having a doped core (16) is pumped (11) by light (18) of a relatively short wavelength to produce fluorescence at a longer wavelength that is detected by detector (24). The level of fluorescence is monitored (26) and evaluated to provide information as to the excitation of the fiber (13) or the environment thereof. In particular, the level of intensity of the detected fluorescence may be used to measure the intensity of a light beam (18) passing axially through an optical fiber system (12) (FIG. 1 ), or the intensity of a light beam (46) passing radially through a fluorescent fiber (13) (FIG. 2 ), or the level of a fluid (32) in a tank (31) (FIG. 3 ), or a scintillation event (37) in a fluorescent fiber (13) pumped to produce amplification of the scintillation event (FIG. 4 ).
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Toeppen, John S.
1994-01-01
A fluorescent fiber (13) having a doped core (16) is pumped (11) by light (18) of a relatively short wavelength to produce fluorescence at a longer wavelength that is detected by detector (24). The level of fluorescence is monitored (26) and evaluated to provide information as to the excitation of the fiber (13) or the environment thereof. In particular, the level of intensity of the detected fluorescence may be used to measure the intensity of a light beam (18) passing axially through an optical fiber system (12) (FIG. 1 ), or the intensity of a light beam (46) passing radially through a fluorescent fiber (13) (FIG. 2 ), or the level of a fluid (32) in a tank (31) (FIG. 3 ), or a scintillation event (37) in a fluorescent fiber (13) pumped to produce amplification of the scintillation event (FIG. 4 ).
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Fugit, Kyle D.; Jyoti, Amar; Upreti, Meenakshi; Anderson, Bradley D.
2014-01-01
A non-invasive fluorescence method was developed to monitor liposomal release kinetics of the anticancer agent topotecan (TPT) in physiological fluids and subsequently used to explore the cause of accelerated release in plasma. Analyses of fluorescence excitation spectra confirmed that unencapsulated TPT exhibits a red shift in its spectrum as pH is increased. This property was used to monitor TPT release from actively loaded liposomal formulations having a low intravesicular pH. Mathematical release models were developed to extract reliable rate constants for TPT release in aqueous solutions monitored by fluorescence and release kinetics obtained by HPLC. Using the fluorescence method, accelerated TPT release was observed in plasma as previously reported in the literature. Simulations to estimate the intravesicular pH were conducted to demonstrate that accelerated release correlated with alterations in the low intravesicular pH. This was attributed to the presence of ammonia in plasma samples rather than proteins and other plasma components generally believed to alter release kinetics in physiological samples. These findings shed light on the critical role that ammonia may play in contributing to the preclinical/clinical variability and performance seen with actively-loaded liposomal formulations of TPT and other weakly-basic anticancer agents. PMID:25456833
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Estimation of Cell Proliferation Dynamics Using CFSE Data
Banks, H.T.; Sutton, Karyn L.; Thompson, W. Clayton; Bocharov, Gennady; Roose, Dirk; Schenkel, Tim; Meyerhans, Andreas
2010-01-01
Advances in fluorescent labeling of cells as measured by flow cytometry have allowed for quantitative studies of proliferating populations of cells. The investigations (Luzyanina et al. in J. Math. Biol. 54:57–89, 2007; J. Math. Biol., 2009; Theor. Biol. Med. Model. 4:1–26, 2007) contain a mathematical model with fluorescence intensity as a structure variable to describe the evolution in time of proliferating cells labeled by carboxyfluorescein succinimidyl ester (CFSE). Here, this model and several extensions/modifications are discussed. Suggestions for improvements are presented and analyzed with respect to statistical significance for better agreement between model solutions and experimental data. These investigations suggest that the new decay/label loss and time dependent effective proliferation and death rates do indeed provide improved fits of the model to data. Statistical models for the observed variability/noise in the data are discussed with implications for uncertainty quantification. The resulting new cell dynamics model should prove useful in proliferation assay tracking and modeling, with numerous applications in the biomedical sciences. PMID:20195910
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Boehlke, Adam; Whidden, Katherine J.; Benzel, William M.
2017-01-01
Determining the chemical and mineralogical variability within fine-grained mudrocks poses analytical challenges but is potentially useful for documenting subtle stratigraphic differences in physicochemical environments that may influence petroleum reservoir properties and behavior. In this study, we investigate the utility of combining principal component analysis (PCA) of X-ray diffraction (XRD) data and portable X-ray fluorescence (pXRF) data to identify simplifying relationships within a large number of samples and subsequently evaluate a subset that encompasses the full spectrum or range of mineral and chemical variability within a vertical section. Samples were collected and analyzed from a vertical core of the Shublik Formation, a heterogeneous, phosphate-rich, calcareous mudstone-to-marl unit deposited in the Arctic Alaska Basin (AAB) during the Middle and Late Triassic. The Shublik is a major petroleum source rock in the Alaskan North Slope, and is considered a prime target for continuous self-sourced resource plays.
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Lei, Rong; Jiang, Hongshan; Hu, Fan; Yan, Jin; Zhu, Shuifang
2017-02-01
Leaf chlorosis induced by plant virus infection has a short fluorescence lifetime, which reflects damaged photosynthetic complexes and degraded chloroplasts. Plant viruses often induce chlorosis and necrosis, which are intimately related to photosynthetic functions. Chlorophyll fluorescence lifetime measurement is a valuable noninvasive tool for analyzing photosynthetic processes and is a sensitive indicator of the environment surrounding the fluorescent molecules. In this study, our central goal was to explore the effect of viral infection on photosynthesis by employing chlorophyll fluorescence lifetime imaging (FLIM), steady-state fluorescence, non-photochemical quenching (NPQ), transmission electron microscopy (TEM), and pigment analysis. The data indicated that the chlorophyll fluorescence lifetime of chlorotic leaves was significantly shorter than that of healthy control leaves, and the fitted short lifetime component of chlorophyll fluorescence of chlorotic leaves was dominant. This dominant short lifetime component may result from damage to the structure of thylakoid, which was confirmed by TEM. The NPQ value of chlorotic leaves was slightly higher than that of healthy green leaves, which can be explained by increased neoxanthin, lutein and violaxanthin content relative to chlorophyll a. The difference in NPQ is slight, but FLIM can provide simple and direct characterization of PSII structure and photosynthetic function. Therefore, this technique shows great potential as a simple and rapid method for studying mechanisms of plant virus infection.
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Fluorescent analysis of interaction of flavonols with hemoglobin and bovine serum albumin
NASA Astrophysics Data System (ADS)
Sentchouk, V. V.; Bondaryuk, E. V.
2007-09-01
We have studied the fluorescent properties of flavonols (quercetin, fisetin, morin, rutin) with the aim of studying possible interaction with hemoglobin and bovine serum albumin (BSA). We observed an increase in the intensity of intrinsic fluorescence for all the flavonols except rutin in the presence of BSA. From the changes in the fluorescence spectra, we concluded that tautomeric forms are formed on interaction with hemoglobin. We determined the interconnection between the structure of related flavonols and their fluorescent properties on interaction with proteins, and we determined the binding constants for binding with BSA and hemoglobin.
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Depth-resolved fluorescence of human ectocervical tissue
NASA Astrophysics Data System (ADS)
Wu, Yicong; Xi, Peng; Cheung, Tak-Hong; Yim, So Fan; Yu, Mei-Yung; Qu, Jianan Y.
2005-04-01
The depth-resolved autofluorescence of normal and dysplastic human ectocervical tissue within 120um depth were investigated utilizing a portable confocal fluorescence spectroscopy with the excitations at 355nm and 457nm. From the topmost keratinizing layer of all ectocervical tissue samples, strong keratin fluorescence with the spectral characteristics similar to collagen was observed, which created serious interference in seeking the correlation between tissue fluorescence and tissue pathology. While from the underlying non-keratinizing epithelial layer, the measured NADH fluorescence induced by 355nm excitation and FAD fluorescence induced by 457nm excitation were strongly correlated to the tissue pathology. The ratios between NADH over FAD fluorescence increased statistically in the CIN epithelial relative to the normal and HPV epithelia, which indicated increased metabolic activity in precancerous tissue. This study demonstrates that the depth-resolved fluorescence spectroscopy can reveal fine structural information on epithelial tissue and potentially provide more accurate diagnostic information for determining tissue pathology.
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Yuan, Yinquan; Ding, Liyun
2011-10-24
For fiber optical sensor made of tapered fiber tip, the effects of the geometrical parameters of tapered tip on two important factors have been investigated. One factor is the intensity of the evanescent wave into fluorescent layer through core-medium interface; the other is the intensity of fluorescence signal transmitted from fluorescent layer to measurement end. A dependence relation of the intensity of fluorescence signal transmitted from fluorescent layer to measurement end upon the geometrical parameters of tapered tip has been obtained. Theoretical results show that the intensity of the evanescent wave into fluorescent layer rises with the decrease of the end diameter of tapered tip, and the increase of the tip length; and the transmitted power of fluorescence signal increases linearly with the increase of the tip length due to the contribution of the side area of tapered tip. © 2011 Optical Society of America
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Fluorogenic Ag+–Tetrazolate Aggregation Enables Efficient Fluorescent Biological Silver Staining
Xie, Sheng; Wong, Alex Y. H.; Kwok, Ryan T. K.; Li, Ying; Su, Huifang; Lam, Jacky W. Y.
2018-01-01
Abstract Silver staining, which exploits the special bioaffinity and the chromogenic reduction of silver ions, is an indispensable visualization method in biology. It is a most popular method for in‐gel protein detection. However, it is limited by run‐to‐run variability, background staining, inability for protein quantification, and limited compatibility with mass spectroscopic (MS) analysis; limitations that are largely attributed to the tricky chromogenic visualization. Herein, we reported a novel water‐soluble fluorogenic Ag+ probe, the sensing mechanism of which is based on an aggregation‐induced emission (AIE) process driven by tetrazolate‐Ag+ interactions. The fluorogenic sensing can substitute the chromogenic reaction, leading to a new fluorescence silver staining method. This new staining method offers sensitive detection of total proteins in polyacrylamide gels with a broad linear dynamic range and robust operations that rival the silver nitrate stain and the best fluorescent stains. PMID:29575702
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NASA Technical Reports Server (NTRS)
Farmer, F. H.; Brown, C. A., Jr.; Jarrett, O., Jr.; Campbell, J. W.; Staton, W. L.
1979-01-01
An aircraft-borne remote system is presented that utilizes narrow-band light from multiple dye lasers to excite selected algae photopigments and then measures the resultant flourescence emitted from chlorophyll a at 685 nm. Tests were conducted with both pure and mixed cultures of marine algae from a series of field tests taken from piers and bridges of Narragansett Bay, and a prototype remote fluorosensor was flown over the Bay during the 1978 winter-spring diatom bloom. Remote fluorescence obtained at hover points over sea-truth stations showed correlations with in situ fluorescence, total chlorophyll a, and cell count. It was concluded that the ratio of remote fluorescence to direct chlorophyll a concentration was less variable than expected, and the distribution of total chlorophyll a between two major photoplankton color groups showed three distinct areas, within the Bay, of green and golden-brown species.
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Charles, Paul T; Davis, Jasmine; Adams, André A; Anderson, George P; Liu, Jinny L; Deschamps, Jeffrey R; Kusterbeck, Anne W
2015-11-01
The development of explosives detection technologies has increased significantly over the years as environmental and national security agencies implement tighter pollution control measures and methods for improving homeland security. 2, 4, 6-Trinitrotoluene (TNT), known primarily as a component in munitions, has been targeted for both its toxicity and carcinogenic properties that if present at high concentrations can be a detriment to both humans, marine and plant ecosystems. Enabling end users with environmental detection and monitoring systems capable of providing real-time, qualitative and quantitative chemical analysis of these toxic compounds would be extremely beneficial. Reported herein is the development of a multi-channeled microfluidic device immobilized with single chain fragment variable (scFv) recombinant proteins specific for the explosive, TNT. Fluorescence displacement immunoassays performed under constant flow demonstrated trace level sensitivity and specificity for TNT. The utility of three multi-channeled devices immobilized with either (1) scFv recombinant protein, (2) biotinylated-scFv (bt-scFv) and (3) monoclonal anti-TNT (whole IgG molecule) were investigated and compared. Fluorescence dose response curves, crossreactivity measurements and limits of detection (LOD) for TNT were determined. Fluorescence displacement immunoassays for TNT in natural seawater demonstrated detection limits at sub-parts-per-billion levels (0.5 ppb) utilizing the microfluidic device with immobilized bt-scFv. Published by Elsevier B.V.
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NASA Astrophysics Data System (ADS)
Goutx, M.; Besson, F.; Bhairy, N.; Germain, C.; Guigue, C.; Wassouf, G.; Beguery, L.; Tedetti, M.
2016-02-01
From July 2014 to February 2015, we deployed the SeaExplorer glider (ALSEAMAR Company, Meyreuil, France) fitted with the 2 optical pathways tryptophan-like (TRY-) and phenanthrenes-like (PHE-) MiniFluo-UV fluorescence sensor (french CNRS patent) and other sensors for hydrological and biogeochemical parameters (T, S, Chla, turbidity, humic-like) along the shelf off Marseille and the northern Mediterranean coast. Our goal was to characterize the distributions of dissolved organic matter (DOM) to assess its spatial variability in relation with biological and hydrological features, and human pressure. Interestingly, TRY-like and PHE-like concentrations displayed independent behavior along the bay of Marseille transects whereas they co-varied with physical and other biogeochemical descriptors near the mouth of the Rhone River. Around this highly anthropogenised area, lower salinities and higher concentrations in Chla, TRY- and PHE-like materials were observed. After rainy weather, waters of low salinity and of higher Chla, TRY- and PHE-like concentrations extended further southwards. Tryptophan-like concentrations showed a significant correlation with salinity and Chla indicating a biological source of DOM related to the Rhône inputs. Phenanthrene has different atypical profiles of other parameters showing patches of high concentrations at the surface throughout the transect (shipping) and at depth (sediment resuspension). The distribution of humic acid was controlled by the photo-bleaching. Southeast of the bay, intrusion of low temperature high salinity water in the surface layer was the likely feature of upwelled waters from subjacent layers. This study highlights the interest of coupling the outstanding maneuverability of SeaExplorer for exploring shallow waters and highly dynamic river mouth to the MiniFluo-UV sensor for analyzing the fluorescence properties of sea water. This work received fundings from the European Union's FP7 program within the framework of "NeXOS" project, for research, technological development and demonstration under grant agreement No 614102, in collaboration with ALSEAMAR Company.
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NASA Technical Reports Server (NTRS)
Hamaguchi, Kenji; Grosso, Nicolas; Kastner, Joel H.; Weintraub, David A.; Richmond, Michael
2009-01-01
The Suzaku X-ray satellite observed the young stellar object V1647 Ori on 2008 October 8 during the new mass accretion outburst reported in August 2008. During the 87 ksec observation with a net exposure of 40 ks, V1647 Ori showed a. high level of X-ray emission with a gradual decrease in flux by a factor of 5 and then displayed an abrupt flux increase by an order of magnitude. Such enhanced X-ray variability was also seen in XMM-Newton observations in 2004 and 2005 during the 2003-2005 outburst, but has rarely been observed for other young stellar objects. The spectrum clearly displays emission from Helium-like iron, which is a signature of hot plasma (kT approx.5 keV). It also shows a fluorescent iron Ka line with a remarkably large equivalent width of approx. 600 eV. Such a, large equivalent width indicates that a part of the incident X-ray emission that irradiates the circumstellar material and/or the stellar surface is hidden from our line of sight. XMM-Newton spectra during the 2003-2005 outburst did not show a strong fluorescent iron Ka line ; so that the structure of the circumstellar gas very close to the stellar core that absorbs and re-emits X-ray emission from the central object may have changed in between 2005 and 2008. This phenomenon may be related to changes in the infrared morphology of McNeil's nebula between 2004 and 2008.
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Novaes, Tatiane Fernandes; Reyes, Alessandra; Matos, Ronilza; Antunes-Pontes, Laura Regina; Marques, Renata Pereira de Samuel; Braga, Mariana Minatel; Diniz, Michele Baffi; Mendes, Fausto Medeiros
2017-05-01
Fluorescence-based methods (FBM) can add objectiveness to diagnosis strategy for caries. Few studies, however, have focused on the evaluation of caries activity. To evaluate the association between quantitative measures obtained with FBM, clinical parameters acquired from the patients, caries detection, and assessment of activity status in occlusal surfaces of primary molars. Six hundred and six teeth from 113 children (4-14 years) were evaluated. The presence of a biofilm, caries experience, and the number of active lesions were recorded. The teeth were assessed using FBM: DIAGNOdent pen (Lfpen) and Quantitative light-induced fluorescence (QLF). As reference standard, all teeth were evaluated using the ICDAS (International Caries Detection and Assessment System) associated with clinical activity assessments. Multilevel regressions compared the FBM values and evaluated the association between the FBM measures and clinical variables related to the caries activity. The measures from the FBM were higher in cavitated lesions. Only, ∆F values distinguished active and inactive lesions. The LFpen measures were higher in active lesions, at the cavitated threshold (56.95 ± 29.60). Following regression analyses, only the presence of visible biofilm on occlusal surfaces (adjusted prevalence ratio = 1.43) and ∆R values of the teeth (adjusted prevalence ratio = 1.02) were associated with caries activity. Some quantitative measures from FBM parameters are associated with caries activity evaluation, which is similar to the clinical evaluation of the presence of visible biofilm. © 2016 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
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Villareal, Tracy A.; Wilson, Cara
2014-01-01
Four wave-propelled autonomous vehicles (Wave Gliders) instrumented with a variety of oceanographic and meteorological sensors were launched from San Francisco, CA in November 2011 for a trans-Pacific (Pac-X) voyage to test platform endurance. Two arrived in Australia, one in Dec 2012 and one in February 2013, while the two destined for Japan both ran into technical difficulties and did not arrive at their destination. The gliders were all equipped with sensors to measure temperature, salinity, turbidity, oxygen, and both chlorophyll and oil fluorescence. Here we conduct an initial assessment of the data set, noting necessary quality control steps and instrument utility. We conduct a validation of the Pac-X dataset by comparing the glider data to equivalent, or near-equivalent, satellite measurements. Sea surface temperature and salinity compared well to satellite measurements. Chl fluorescence from the gliders was more poorly correlated, with substantial between glider variability. Both turbidity and oil CDOM sensors were compromised to some degree by interfering processes. The well-known diel cycle in chlorophyll fluorescence was observed suggesting that mapping physiological data over large scales is possible. The gliders captured the Pacific Ocean’s major oceanographic features including the increased chlorophyll biomass of the California Current and equatorial upwelling. A comparison of satellite sea surface salinity (Aquarius) and glider-measured salinity revealed thin low salinity lenses in the southwestern Pacific Ocean. One glider survived a direct passage through a tropical cyclone. Two gliders traversed an open ocean phytoplankton bloom; extensive spiking in the chlorophyll fluorescence data is consistent with aggregation and highlights another potential future use for the gliders. On long missions, redundant instrumentation would aid in interpreting unusual data streams, as well as a means to periodically image the sensor heads. Instrument placement is critical to minimize bubble-related problems in the data. PMID:24658053
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Villareal, Tracy A; Wilson, Cara
2014-01-01
Four wave-propelled autonomous vehicles (Wave Gliders) instrumented with a variety of oceanographic and meteorological sensors were launched from San Francisco, CA in November 2011 for a trans-Pacific (Pac-X) voyage to test platform endurance. Two arrived in Australia, one in Dec 2012 and one in February 2013, while the two destined for Japan both ran into technical difficulties and did not arrive at their destination. The gliders were all equipped with sensors to measure temperature, salinity, turbidity, oxygen, and both chlorophyll and oil fluorescence. Here we conduct an initial assessment of the data set, noting necessary quality control steps and instrument utility. We conduct a validation of the Pac-X dataset by comparing the glider data to equivalent, or near-equivalent, satellite measurements. Sea surface temperature and salinity compared well to satellite measurements. Chl fluorescence from the gliders was more poorly correlated, with substantial between glider variability. Both turbidity and oil CDOM sensors were compromised to some degree by interfering processes. The well-known diel cycle in chlorophyll fluorescence was observed suggesting that mapping physiological data over large scales is possible. The gliders captured the Pacific Ocean's major oceanographic features including the increased chlorophyll biomass of the California Current and equatorial upwelling. A comparison of satellite sea surface salinity (Aquarius) and glider-measured salinity revealed thin low salinity lenses in the southwestern Pacific Ocean. One glider survived a direct passage through a tropical cyclone. Two gliders traversed an open ocean phytoplankton bloom; extensive spiking in the chlorophyll fluorescence data is consistent with aggregation and highlights another potential future use for the gliders. On long missions, redundant instrumentation would aid in interpreting unusual data streams, as well as a means to periodically image the sensor heads. Instrument placement is critical to minimize bubble-related problems in the data.
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NASA Astrophysics Data System (ADS)
Hirst, Edwin; Kaye, Paul H.; Foot, Virginia E.; Clark, James M.; Withers, Philip B.
2004-12-01
We describe the construction of a bio-aerosol monitor designed to capture and record intrinsic fluorescence spectra from individual aerosol particles carried in a sample airflow and to simultaneously capture data relating to the spatial distribution of elastically scattered light from each particle. The spectral fluorescence data recorded by this PFAS (Particle Fluorescence and Shape) monitor contains information relating to the particle material content and specifically to possible biological fluorophores. The spatial scattering data from PFAS yields information relating to particle size and shape. The combination of these data can provide a means of aiding the discrimination of bio-aerosols from background or interferent aerosol particles which may have similar fluorescence properties but exhibit shapes and/or sizes not normally associated with biological particles. The radiation used both to excite particle fluorescence and generate the necessary spatially scattered light flux is provided by a novel compact UV fiber laser operating at 266nm wavelength. Particles drawn from the ambient environment traverse the laser beam in single file. Intrinsic particle fluorescence in the range 300-570nm is collected via an ellipsoidal concentrator into a concave grating spectrometer, the spectral data being recorded using a 16-anode linear array photomultiplier detector. Simultaneously, the spatial radiation pattern scattered by the particle over 5°-30° scattering angle and 360° of azimuth is recorded using a custom designed 31-pixel radial hybrid photodiode array. Data from up to ~5,000 particles per second may be acquired for analysis, usually performed by artificial neural network classification.
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Mosaic-Detector-Based Fluorescence Spectral Imager
NASA Technical Reports Server (NTRS)
Son, Kyung-Ah; Moon, Jeong
2007-01-01
A battery-powered, pen-sized, portable instrument for measuring molecular fluorescence spectra of chemical and biological samples in the field has been proposed. Molecular fluorescence spectroscopy is among the techniques used most frequently in laboratories to analyze compositions of chemical and biological samples. Heretofore, it has been possible to measure fluorescence spectra of molecular species at relative concentrations as low as parts per billion (ppb), with a few nm spectral resolution. The proposed instrument would include a planar array (mosaic) of detectors, onto which a fluorescence spectrum would be spatially mapped. Unlike in the larger laboratory-type molecular fluorescence spectrometers, mapping of wavelengths to spatial positions would be accomplished without use of relatively bulky optical parts. The proposed instrument is expected to be sensitive enough to enable measurement of spectra of chemical species at relative concentrations <1 ppb, with spectral resolution that could be tailored by design to be comparable to a laboratory molecular fluorescence spectrometer. The proposed instrument (see figure) would include a button-cell battery and a laser diode, which would generate the monochromatic ultraviolet light needed to excite fluorescence in a sample. The sample would be held in a cell bounded by far-ultraviolet-transparent quartz or optical glass. The detector array would be, more specifically, a complementary metal oxide/ semiconductor or charge-coupled- device imaging photodetector array, the photodetectors of which would be tailored to respond to light in the wavelength range of the fluorescence spectrum to be measured. The light-input face of the photodetector array would be covered with a matching checkerboard array of multilayer thin film interference filters, such that each pixel in the array would be sensitive only to light in a spectral band narrow enough so as not to overlap significantly with the band of an adjacent pixel. The wavelength interval between adjacent pixels (and, thus, the spectral resolution) would typically be chosen by design to be approximately equal to the width of the total fluorescence wavelength range of interest divided by the number of pixels. The unitary structure comprising the photodetector array overlaid with the matching filter array would be denoted a hyperspectral mosaic detector (HMD) array.
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Use of fluorescence spectroscopy to control ozone dosage in recirculating aquaculture systems.
Spiliotopoulou, Aikaterini; Martin, Richard; Pedersen, Lars-Flemming; Andersen, Henrik R
2017-03-15
The aim of this study was to investigate the potential of fluorescence spectroscopy to be used as an ozone dosage determination tool in recirculating aquaculture systems (RASs), by studying the relationship between fluorescence intensities and dissolved organic matter (DOM) degradation by ozone, in order to optimise ozonation treatment. Water samples from six different Danish facilities (two rearing units from a commercial trout RAS, a commercial eel RAS, a pilot RAS and two marine water aquariums) were treated with different O 3 dosages (1.0-20.0 mg/L ozone) in bench-scale experiments, following which fluorescence intensity degradation was eventually determined. Ozonation kinetic experiments showed that RAS water contains fluorescent organic matter, which is easily oxidised upon ozonation in relatively low concentrations (0-5 mg O 3 /L). Fluorescence spectroscopy has a high level of sensitivity and selectivity in relation to associated fluorophores, and it is able to determine accurately the ozone demand of each system. The findings can potentially be used to design offline or online sensors based on the reduction by ozone of natural fluorescent-dissolved organic matter in RAS. The suggested indirect determination of ozone delivered into water can potentially contribute to a safer and more adequate ozone-based treatment to improve water quality. Copyright © 2016 Elsevier Ltd. All rights reserved.
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[Determination of chromphoric dissolved organic matter in water from different sources].
Liu, Xian-ping; Li, Lei; Dai, Jin-feng; Wang, Xiao-ru; Lee, Frank S C
2007-10-01
Chromophoric dissolved organic matter (CDOM) represents the fraction of the dissolved organic pool which absorbs light in the visible as well as UV ranges. It could affect the color of the waters. It is necessary to study it during in research on ecosystem, remote sensing of the water color and the cycle of carbon in waters. CDOM can fluoresce when excited, so fluorescence spectrum has been used to study its origin, distribution, and change. In the present article the fluorescence spectrophotometer was used to study the relation between the fluorescence intensity, spectrum area and the concentration of CDOM. When the concentration of CDOM is low (less than 75 mg x L(-1)), there is a better linear relationship (r2 > 0.98) between the fluorescence intensity, the spectrum area and the concentration of CDOM. Meanwhile good linear relations were found between the fluorescence intensity and spectrum area, which showed the same changeable trend of the fluorescence intensity and spectrum area with the concentration change of CDOM. A method was established to quantify the concentration of CDOM in water from different source using the linear relationship between the spectrum area and the concentration. It suits the complicated constituent analysis of CDOM and could really and accurately show the concentration of CDOM in natural water.
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Sheaff, Chrystal N; Eastwood, Delyle; Wai, Chien M
2007-01-01
The detection of explosive material is at the forefront of current analytical problems. A detection method is desired that is not restricted to detecting only explosive materials, but is also capable of identifying the origin and type of explosive. It is essential that a detection method have the selectivity to distinguish among compounds in a mixture of explosives. The nitro compounds found in explosives have low fluorescent yields or are considered to be non-fluorescent; however, after reduction, the amino compounds exhibit relatively high fluorescence. We discuss how to increase selectivity of explosive detection using fluorescence; this includes synchronous luminescence and derivative spectroscopy with appropriate smoothing. By implementing synchronous luminescence and derivative spectroscopy, we were able to resolve the reduction products of one major TNT-based explosive compound, 2,4-diaminotoluene, and the reduction products of other minor TNT-based explosives in a mixture. We also report for the first time the quantum yields of these important compounds. Relative quantum yields are useful in establishing relative fluorescence intensities and are an important spectroscopic measurement of molecules. Our approach allows for rapid, sensitive, and selective detection with the discrimination necessary to distinguish among various explosives.
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[Fluorescence spectra and quantum yield of TiO2 nanocrystals synthesized by alcohothermal method].
Song, Cui-Hong; Li, Yan-Ting; Li, Jing; Wei, Yong-Ju; Hu, Yu-Zhu; Wei, Yu
2008-01-01
Fluorescence spectra and fluorescence quantum yield of TiO2 nanocrystals were studied. Using tetra n-butyl titanate as a starting material, a facile alcohothermal technique was used to synthesize TiO2 nanocrystals. As can be seen from the transmittance electron microscopy (TEM) image, TiO2 nanocrystals with a relatively uniform particle size distribution of < 10 nm are present in the transparent sol. The transparent sol presents a strong stable fluorescence emission with a maximum at 450 nm, which is greatly dependent on the size quantization effects, defect energy level and the surface state of TiO2 nanocrystals. The quantum yield (gamma) of TiO2 was determined by the relative comparison procedure, using freshly prepared analytical purity quinine sulfate in 0.05 mol x L(-1) H2SO4 as a relative quantum yield standard. The emission quantum yield of TiO2 nanocrystals prepared in alcoholic media was calculated to be about 0.20 at wavelengths ranging from 330 to 370 nm, which was much higher than the values reported in previous works. So, it is supposed that nano-TiO2 will be applied as a potential quantum dots fluorescence probe in biological analysis.
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Santolaria, Pilar; Pauciullo, Alfredo; Silvestre, Miguel A; Vicente-Fiel, Sandra; Villanova, Leyre; Pinton, Alain; Viruel, Juan; Sales, Ester; Yániz, Jesús L
2016-01-01
This study was designed to determine the ability of computer-assisted sperm morphometry analysis (CASA-Morph) with fluorescence to discriminate between spermatozoa carrying different sex chromosomes from the nuclear morphometrics generated and different statistical procedures in the bovine species. The study was divided into two experiments. The first was to study the morphometric differences between X- and Y-chromosome-bearing spermatozoa (SX and SY, respectively). Spermatozoa from eight bulls were processed to assess simultaneously the sex chromosome by FISH and sperm morphometry by fluorescence-based CASA-Morph. SX cells were larger than SY cells on average (P < 0.001) although with important differences between bulls. A simultaneous evaluation of all the measured features by discriminant analysis revealed that nuclear area and average fluorescence intensity were the variables selected by stepwise discriminant function analysis as the best discriminators between SX and SY. In the second experiment, the sperm nuclear morphometric results from CASA-Morph in nonsexed (mixed SX and SY) and sexed (SX) semen samples from four bulls were compared. FISH allowed a successful classification of spermatozoa according to their sex chromosome content. X-sexed spermatozoa displayed a larger size and fluorescence intensity than nonsexed spermatozoa (P < 0.05). We conclude that the CASA-Morph fluorescence-based method has the potential to find differences between X- and Y-chromosome-bearing spermatozoa in bovine species although more studies are needed to increase the precision of sex determination by this technique.
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Applicability of Fluorescence and Absorbance Spectroscopy to Estimate Organic Pollution in Rivers
Knapik, Heloise Garcia; Fernandes, Cristovão Vicente Scapulatempo; de Azevedo, Júlio Cesar Rodrigues; do Amaral Porto, Monica Ferreira
2014-01-01
Abstract This article explores the applicability of fluorescence and absorbance spectroscopy for estimating organic pollution in polluted rivers. The relationship between absorbance, fluorescence intensity, dissolved organic carbon, biochemical oxygen demand (BOD), chemical oxygen demand (COD), and other water quality parameters were used to characterize and identify the origin and the spatial variability of the organic pollution in a highly polluted watershed. Analyses were performed for the Iguassu River, located in southern Brazil, with area about 2,700 km2 and ∼3 million inhabitants. Samples were collect at six monitoring sites covering 107 km of the main river. BOD, COD, nitrogen, and phosphorus concentration indicates a high input of sewage to the river. Specific absorbance at 254 and 285 nm (SUVA254 and A285/COD) did not show significant variation between sites monitored, indicating the presence of both dissolved compounds found in domestic effluents and humic and fulvic compounds derived from allochthonous organic matter. Correlations between BOD and tryptophan-like fluorescence peak (peak T2, r=0.7560, and peak T1, r=0.6949) and tyrosine-like fluorescence peak (peak B, r=0.7321) indicated the presence of labile organic matter and thus confirmed the presence of sewage in the river. Results showed that fluorescence and absorbance spectroscopy provide useful information on pollution in rivers from critical watersheds and together are a robust method that is simpler and more rapid than traditional methods employed by regulatory agencies. PMID:25469076
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Horton, P; Black, M T
1981-03-12
Addition of ATP to chloroplasts causes a reversible 25-30% decrease in chlorophyll fluorescence. This quenching is light-dependent, uncoupler insensitive but inhibited by DCMU and electron acceptors and has a half-time of 3 minutes. Electron donors to Photosystem I can not overcome the inhibitory effect of DCMU, suggesting that light activation depends on the reduced state of plastoquinone. Fluorescence emission spectra recorded at -196 degrees C indicate that ATP treatment increases the amount of excitation energy transferred to Photosystem I. Examination of fluorescence induction curves indicate that ATP treatment decreases both the initial (F0) and variable (Fv) fluorescence such that the ratio of Fv to the maximum (Fm) yield is unchanged. The initial sigmoidal phase of induction is slowed down by ATP treatment and is quenched 3-fold more than the exponential slow phase, the rate of which is unchanged. A plot of Fv against area above the induction curve was identical plus or minus ATP. Thus ATP treatment can alter quantal distribution between Photosystems II and I without altering Photosystem II-Photosystem II interaction. The effect of ATP strongly resembles in its properties the phosphorylation of the light-harvesting complex by a light activated, ATP-dependent protein kinase found in chloroplast membranes and could be the basis of physiological mechanisms which contribute to slow fluorescence quenching in vivo and regulate excitation energy distribution between Photosystem I and II. It is suggested that the sensor for this regulation is the redox state of plastoquinone.
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Sarkar, Sumit; Schmued, Larry
2012-06-01
We have aimed to develop novel histochemical markers for the labeling of brain pericytes and characterize their morphology in the normal and the excitotoxin-exposed brain, as this class of cells has received little attention until recently. Pericyte labeling was accomplished by the intracerebroventricular injection of certain fluorescent dextran conjugates, such as Fluoro-Gold-dextran, FR-dextran, FITC-dextran and Fluoro-Turquoise (FT)-dextran. 1-7 days after the tracer injection, extensive labeling of vascular pericytes was seen throughout the entire brain. These cells were found distal to the endothelial cells and exhibited large dye containing vacuoles. The morphology of the pericytes was somewhat variable, exhibiting round or amoeboid shapes within larger intracellular vesicles, while those wrapping around capillaries exhibited a more elongated appearance with finger-like projections. The use of FG-dextran resulted in bluish yellow fluorescently labeled pericytes, while FR-dextran resulted in red fluorescent labeled pericytes, FITC-dextran exhibited green fluorescent pericytes and FT-dextran showed fluorescent blue pericytes in the brain. We have used these tracers to study possible changes in morphology and pericyte number following kainic acid insult, observing that the number of pericytes in the injured or lesioned areas of the brain is dramatically reduced compared to the non-injured areas. These novel fluorochromes should be of use for studies involving the detection and localization of pericytes in both normal and pathological brain tissues. Published by Elsevier B.V.
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Zhang, Pengfei; Kong, Lingbo; Wang, Guiwen; Setlow, Peter; Li, Yong-qing
2011-01-01
Dynamic processes during wet-heat treatment of individual spores of Bacillus cereus, Bacillus megaterium, and Bacillus subtilis at 80 to 90°C were investigated using dual-trap Raman spectroscopy, differential interference contrast (DIC) microscopy, and nucleic acid stain (SYTO 16) fluorescence microscopy. During spore wet-heat treatment, while the spores' 1:1 chelate of Ca2+ with dipicolinic acid (CaDPA) was released rapidly at a highly variable time Tlag, the levels of spore nucleic acids remained nearly unchanged, and the Tlag times for individual spores from the same preparation were increased somewhat as spore levels of CaDPA increased. The brightness of the spores' DIC image decreased by ∼50% in parallel with CaDPA release, and there was no spore cortex hydrolysis observed. The lateral diameters of the spores' DIC image and SYTO 16 fluorescence image also decreased in parallel with CaDPA release. The SYTO 16 fluorescence intensity began to increase during wet-heat treatment at a time before Tlag and reached maximum at a time slightly later than Trelease. However, the fluorescence intensities of wet-heat-inactivated spores were ∼15-fold lower than those of nutrient-germinated spores, and this low SYTO 16 fluorescence intensity may be due in part to the low permeability of the dormant spores' inner membranes to SYTO 16 and in part to nucleic acid denaturation during the wet-heat treatment. PMID:21602365
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Schaafsma, Boudewijn E.; Mieog, J.Sven D.; Hutteman, Merlijn; van der Vorst, Joost R.; Kuppen, Peter J.K.; Löwik, Clemens W.G.M.; Frangioni, John V.; van de Velde, Cornelis J.H.; Vahrmeijer, Alexander L.
2011-01-01
Optical imaging using near-infrared (NIR) fluorescence provides new prospects for general and oncologic surgery. ICG is currently utilised in NIR fluorescence cancer-related surgery for three indications: sentinel lymph node (SLN) mapping, intraoperative identification of solid tumours, and angiography during reconstructive surgery. Therefore, understanding its advantages and limitations is of significant importance. Although non-targeted and non-conjugatable, ICG appears to be laying the foundation for more widespread use of NIR fluorescence-guided surgery. PMID:21495033
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Zhang, Jiulou; Shi, Junwei; Guang, Huizhi; Zuo, Simin; Liu, Fei; Bai, Jing; Luo, Jianwen
2016-06-01
High-intensity background fluorescence is generally encountered in fluorescence molecular tomography (FMT), because of the accumulation of fluorescent probes in nontarget tissues or the existence of autofluorescence in biological tissues. The reconstruction results are affected or even distorted by the background fluorescence, especially when the distribution of fluorescent targets is relatively sparse. The purpose of this paper is to reduce the negative effect of background fluorescence on FMT reconstruction. After each iteration of the Tikhonov regularization algorithm, 3-D discrete cosine transform is adopted to filter the intermediate results. And then, a sparsity constraint step based on L1 regularization is applied to restrain the energy of the objective function. Phantom experiments with different fluorescence intensities of homogeneous and heterogeneous background are carried out to validate the performance of the proposed scheme. The results show that the reconstruction quality can be improved with the proposed iterative correction scheme. The influence of background fluorescence in FMT can be reduced effectively because of the filtering of the intermediate results, the detail preservation, and noise suppression of L1 regularization.
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The OH + HBr reaction revisited
NASA Technical Reports Server (NTRS)
Ravishankara, A. R.; Wine, P. H.; Wells, J. R.
1985-01-01
Variable-temperature measurements of the rate coefficient /k(1)/ for the reaction OH + HBr yield Br + H2O are presented. The measurements are verified by two techniques: one involved a 266-nm pulsed-laser photolysis of O3/H2O/HBr/He mixtures in conjunction with time-resolved resonance fluorescence detection of OH, the second comprised pulsed laser-induced fluorescence detection of OH following 248-nm pulsed-laser photolysis of H2O2/HBr/Ar mixtures. It is reported that k(1) = (11.9 + or -1.4 x 10 to the -12th (cu cm)/(molecule)(s) independent of temperature. The measurements are compared with other available results.
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IR-stimulated visible fluorescence in pink and brown diamond.
Byrne, K S; Chapman, J G; Luiten, A N
2014-03-19
Irradiation of natural pink and brown diamond by middle-ultraviolet light (photon energy ϵ ≥ 4.1 eV ) is seen to induce anomalous fluorescence phenomena at N3 defect centres (structure N3-V). When diamonds primed in this fashion are subsequently exposed to infrared light (even with a delay of many hours), a transient burst of blue N3 fluorescence is observed. The dependence of this IR-triggered fluorescence on pump wavelength and intensity suggest that this fluorescence phenomena is intrinsically related to pink diamond photochromism. An energy transfer process between N3 defects and other defect species can account for both the UV-induced fluorescence intensity changes, and the apparent optical upconversion of IR light. From this standpoint, we consider the implications of this N3 fluorescence behaviour for the current understanding of pink diamond photochromism kinetics.
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Improved sensitivity to fluorescence for cancer detection in wide-field image-guided neurosurgery
Jermyn, Michael; Gosselin, Yoann; Valdes, Pablo A.; Sibai, Mira; Kolste, Kolbein; Mercier, Jeanne; Angulo, Leticia; Roberts, David W.; Paulsen, Keith D.; Petrecca, Kevin; Daigle, Olivier; Wilson, Brian C.; Leblond, Frederic
2015-01-01
In glioma surgery, Protoporphyrin IX (PpIX) fluorescence may identify residual tumor that could be resected while minimizing damage to normal brain. We demonstrate that improved sensitivity for wide-field spectroscopic fluorescence imaging is achieved with minimal disruption to the neurosurgical workflow using an electron-multiplying charge-coupled device (EMCCD) relative to a state-of-the-art CMOS system. In phantom experiments the EMCCD system can detect at least two orders-of-magnitude lower PpIX. Ex vivo tissue imaging on a rat glioma model demonstrates improved fluorescence contrast compared with neurosurgical fluorescence microscope technology, and the fluorescence detection is confirmed with measurements from a clinically-validated spectroscopic probe. Greater PpIX sensitivity in wide-field fluorescence imaging may improve the residual tumor detection during surgery with consequent impact on survival. PMID:26713218
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Wei, Zhangwen; Gu, Zhi-Yuan; Arvapally, Ravi K; Chen, Ying-Pin; McDougald, Roy N; Ivy, Joshua F; Yakovenko, Andrey A; Feng, Dawei; Omary, Mohammad A; Zhou, Hong-Cai
2014-06-11
We demonstrate that rigidifying the structure of fluorescent linkers by structurally constraining them in metal-organic frameworks (MOFs) to control their conformation effectively tunes the fluorescence energy and enhances the quantum yield. Thus, a new tetraphenylethylene-based zirconium MOF exhibits a deep-blue fluorescent emission at 470 nm with a unity quantum yield (99.9 ± 0.5%) under Ar, representing ca. 3600 cm(-1) blue shift and doubled radiative decay efficiency vs the linker precursor. An anomalous increase in the fluorescence lifetime and relative intensity takes place upon heating the solid MOF from cryogenic to ambient temperatures. The origin of these unusual photoluminescence properties is attributed to twisted linker conformation, intramolecular hindrance, and framework rigidity.
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Olapade, Ola A; Pung, Kayleigh
2012-06-01
Plant-microbial interactions have been well studied because of the ecological importance of such relationships in aquatic systems. However, general knowledge regarding the composition of these biofilm communities is still evolving, partly as a result of several confounding factors that are attributable to plant host properties and to hydrodynamic conditions in aquatic environments. In this study, the occurrences of various bacterial phylogenetic taxa on 2 native plants, i.e., mayapple (Podophyllum peltatum L.) and cow parsnip (Heracleum maximum Bartram), and on an invasive species, i.e., garlic mustard (Alliaria petiolata (M. Bieb.) Cavara & Grande), were quantitatively examined using nucleic acid staining and fluorescence in situ hybridization. The plants were incubated in triplicates for about a week within the Kalamazoo River and Pierce Cedar Creek as well as in microcosms. The bacterial groups targeted for enumeration are known to globally occur in relatively high abundance and are also ubiquitously distributed in freshwater environments. Fluorescence in situ hybridization analyses of the bacterioplankton assemblages revealed that the majority of bacterial cells that hybridized with the different probes were similar between the 2 sites. In contrast, the plant-associated populations while similar on the 3 plants incubated in Kalamazoo River, their representations were highest on the 2 native plants relative to the invasive species in Pierce Cedar Creek. Overall, our results further suggested that epiphytic bacterial assemblages are probably under the influences of and probably subsequently respond to multiple variables and conditions in aquatic milieus.
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Photobiology of Symbiodinium revisited: bio-physical and bio-optical signatures
NASA Astrophysics Data System (ADS)
Hennige, S. J.; Suggett, D. J.; Warner, M. E.; McDougall, K. E.; Smith, D. J.
2009-03-01
Light is often the most abundant resource within the nutrient-poor waters surrounding coral reefs. Consequently, zooxanthellae ( Symbiodinium spp.) must continually photoacclimate to optimise productivity and ensure coral success. In situ coral photobiology is becoming dominated by routine assessments using state-of-the-art non-invasive bio-optical or chlorophyll a fluorescence (bio-physical) techniques. Multiple genetic types of Symbiodinium are now known to exist; however, little focus has been given as to how these types differ in terms of characteristics that are observable using these techniques. Therefore, this investigation aimed to revisit and expand upon a pivotal study by Iglesias-Prieto and Trench (1994) by comparing the photoacclimation characteristics of different Symbiodinium types based on their bio-physical (chlorophyll a fluorescence, reaction centre counts) and bio-optical (optical absorption, pigment concentrations) ‘signatures’. Signatures described here are unique to Symbiodinium type and describe phenotypic responses to set conditions, and hence are not suitable to describe taxonomic structure of in hospite Symbiodinium communities. In this study, eight Symbiodinium types from clades and sub-clades (A-B, F) were grown under two PFDs (Photon Flux Density) and examined. The photoacclimation response by Symbiodinium was highly variable between algal types for all bio-physical and for many bio-optical measurements; however, a general preference to modifying reaction centre content over effective antennae-absorption was observed. Certain bio-optically derived patterns, such as light absorption, were independent of algal type and, when considered per photosystem, were matched by reaction centre stoichiometry. Only by better understanding genotypic and phenotypic variability between Symbiodinium types can future studies account for the relative taxonomic and physiological contribution by Symbiodinium to coral acclimation.
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NASA Technical Reports Server (NTRS)
Clapp, L. H.; Twiss, R. G.; Cattolica, R. J.
1991-01-01
Experimental results are presented related to the radial spread of fluorescence excited by 10 and 20 KeV electron beams passing through nonflowing rarefied nitrogen at 293 K. An imaging technique for obtaining species distributions from measured beam-excited fluorescence is described, based on a signal inversion scheme mathematically equivalent to the inversion of the Abel integral equation. From fluorescence image data, measurements of beam radius, integrated signal intensity, and spatially resolved distributions of N2(+) first-negative-band fluorescence-emitting species have been made. Data are compared with earlier measurements and with an heuristic beam spread model.
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Research on fluorescence detection method of Microcystis aeruginosa
NASA Astrophysics Data System (ADS)
Wang, Xiao-xiong
2017-07-01
The paper studied the viability determination of Microcystis aeruginosa by FDA and PI staining. The staining results were measured by fluorescence microscopy. The results indicated that viable and dead cells were stained as bright green and red fluorescent respectively by FDA and PI. Through PI-FDA dual color fluorescence staining, the color of green and red distinct obviously by fluorescence microscope. The staining rate has relation with the cell density. If the cell density of M. aeruginosa was 1.0×107-1.0×109 cell·mL-1, the staining rate would be 100.0% or 98.0% by PI and of FDA respectively.
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NASA Astrophysics Data System (ADS)
Galán, Alexander; Molina, Verónica; Belmar, Lucy; Ulloa, Osvaldo
2012-01-01
The phylogenetic affiliation and temporal variability in the abundance of planktonic anammox bacteria were studied at a time-series station above the continental shelf off central Chile (∼36°S; bottom depth 93 m), a wind-driven, seasonal upwelling area, between August 2006 and April 2008. The study was carried out by cloning and sequencing the 16S rRNA gene and by using catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH). Our results showed the presence of a single anammox bacteria-like ribotype during both upwelling and non-upwelling seasons, which was phylogenetically associated with a recently described oxygen-minimum-zone subcluster within the Candidatus Scalindua clade. Moreover, clear differences were observed in the temporal and vertical distribution of anammox cells. During the upwelling season (austral spring-summer), relatively high abundances (∼5500 cells mL -1) and large cells (0.8 μm 3-75.7 fg C cell -1) were found below 20 m depth. In contrast, during the non-upwelling season (austral fall-winter), lower abundances (∼600 cells mL -1) and smaller cells (0.1 μm 3-22.8 fg C cell -1) were found, predominantly associated with the bottom layer. Overall, our results indicate that the abundance and vertical distribution of anammox planktonic assemblages are related to the occurrence of seasonal, wind-driven, coastal upwelling, which in turn appears to offer favorable conditions for the development of these microorganisms. The dominance of a unique anammox bacteria-like ribotype could be related to the high environmental variability observed in the system, which prevents the establishment of other anammox lineages.
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Wan, Yuhang; Carlson, John A; Kesler, Benjamin A; Peng, Wang; Su, Patrick; Al-Mulla, Saoud A; Lim, Sung Jun; Smith, Andrew M; Dallesasse, John M; Cunningham, Brian T
2016-07-08
A compact analysis platform for detecting liquid absorption and emission spectra using a set of optical linear variable filters atop a CMOS image sensor is presented. The working spectral range of the analysis platform can be extended without a reduction in spectral resolution by utilizing multiple linear variable filters with different wavelength ranges on the same CMOS sensor. With optical setup reconfiguration, its capability to measure both absorption and fluorescence emission is demonstrated. Quantitative detection of fluorescence emission down to 0.28 nM for quantum dot dispersions and 32 ng/mL for near-infrared dyes has been demonstrated on a single platform over a wide spectral range, as well as an absorption-based water quality test, showing the versatility of the system across liquid solutions for different emission and absorption bands. Comparison with a commercially available portable spectrometer and an optical spectrum analyzer shows our system has an improved signal-to-noise ratio and acceptable spectral resolution for discrimination of emission spectra, and characterization of colored liquid's absorption characteristics generated by common biomolecular assays. This simple, compact, and versatile analysis platform demonstrates a path towards an integrated optical device that can be utilized for a wide variety of applications in point-of-use testing and point-of-care diagnostics.
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Scales of variability of bio-optical properties as observed from near-surface drifters
NASA Technical Reports Server (NTRS)
Abbott, Mark R.; Brink, Kenneth H.; Booth, C. R.; Blasco, Dolors; Swenson, Mark S.; Davis, Curtiss O.; Codispoti, L. A.
1995-01-01
A drifter equipped with bio-optical sensors and an automated water sampler was deployed in the California Current as part of the coastal transition zone program to study the biological, chemical, and physical dynamics of the meandering filaments. During deployments in 1987 and 1988, measurements were made of fluorescence, downwelling irradiance, upwelling radiance, and beam attenuation using several bio-optical sensors. Samples were collected by an automated sampler for later analysis of nutrients and phytoplankton species compositon. Large-scale spatial and temporal changes in the bio-optical and biological properties of the region were driven by changes in phytoplankton species composition which, in turn, were associated with the meandering circulation. Variance spectra of the bio-optical paramenters revealed fluctuations on both diel and semidiurnal scales, perhaps associated with solar variations and internal tides, respectively. Offshore, inertial-scale fluctuations were apparent in the variance spectra of temperature, fluorescence, and beam attenuation. Although calibration samples can help remove some of these variations, these results suggest that the use of bio-optical data from unattended platforms such as moorings and drifters must be analyzed carefully. Characterization of the scaled of phytoplankton variability must account for the scales of variability in the algorithms used to convert bio-optical measurments into biological quantities.
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Photochemically stable fluorescent heteroditopic ligands for zinc ion.
Zhang, Lu; Zhu, Lei
2008-11-07
Photochemically stable fluorescent heteroditopic ligands (9 and 10) for zinc ion were prepared and studied. Two independent metal coordination-driven photophysical processes, chelation-enhanced fluorescence (CHEF) and internal (or intramolecular) charge transfer (ICT), were designed into our heteroditopic ligand framework. This strategy successfully relates three coordination states of a ligand, non-, mono-, and dicoordinated, to three fluorescence states, fluorescence OFF, ON at one wavelength, and ON at another wavelength. This ligand platform has provided chemical foundation for applications such as the quantification of zinc concentration over broad ranges (Zhang, L.; Clark, R. J.; Zhu, L. Chem.-Eur. J. 2008, 14, 2894-2903) and molecular logic functions (Zhang, L.; Whitfield, W. A.; Zhu, L. Chem. Commun. 2008, 1880-1882). The binding stoichiometries of dipicolylamino and 2,2'-bipyridyl, the two binding sites featured in heteroditopic ligands 7-10, were studied in acetonitrile using both Job's method of continuous variation and isothermal titration calorimetry (ITC). The fluorescence enhancement of 7-10 upon the formation of monozinc complexes (defined as the fluorescence quantum yield ratio of monozinc complex and free ligand) is qualitatively related to the highest occupied molecular orbital (HOMO) energy levels of their fluorophores. This is consistent with our hypothesis on the thermodynamics of the coordination-driven photophysical processes embodied in the designed heteroditopic system, which was supported by cyclic voltammetry studies. In conclusion, compounds 9 and 10 not only possess better photochemical stability but also display a higher degree of fluorescence turn-on upon formation of monozinc complexes than their vinyl counterparts 7 and 8.
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Eisenberg, Azaria Solomon; Juszczak, Laura J
2013-07-05
Molecular dynamics (MD), coupled with fluorescence data for charged dipeptides of tryptophanyl glutamic acid (Trp-Glu), reveal a detailed picture of how specific conformation affects fluorescence. Fluorescence emission spectra and time-resolved emission measurements have been collected for all four charged species. MD simulations 20 to 30 ns in length have also been carried out for the Trp-Glu species, as simulation provides aqueous phase conformational data that can be correlated with the fluorescence data. The calculations show that each dipeptide species is characterized by a similar set of six, discrete Chi 1, Chi 2 dihedral angle pairs. The preferred Chi 1 angles--60°, 180°, and 300°--play the significant role in positioning the terminal amine relative to the indole ring. A Chi 1 angle of 60° results in the arching of the backbone over the indole ring and no interaction of the ring with the terminal amine. Chi 1 values of 180° and 300° result in an extension of the backbone away from the indole ring and a NH3 cation-π interaction with indole. This interaction is believed responsible for charge transfer quenching. Two fluorescence lifetimes and their corresponding amplitudes correlate with the Chi 1 angle probability distribution for all four charged Trp-Glu dipeptides. Fluorescence emission band maxima are also consistent with the proposed pattern of terminal amine cation quenching of fluorescence. Copyright © 2013 Wiley Periodicals, Inc.
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[Investigation of quantitative detection of water quality using spectral fluorescence signature].
He, Jun-hua; Cheng, Yong-jin; Han, Yan-ling; Zhang, Hao; Yang, Tao
2008-08-01
A method of spectral analysis, which can simultaneously detect dissolved organic matter (DOM) and chlorophyll a (Chl-a) in natural water, was developed in the present paper with the intention of monitoring water quality fast and quantitatively. Firstly, the total luminescence spectra (TLS) of water sample from East Lake in Wuhan city were measured by the use of laser (532 nm) induced fluorescence (LIF). There were obvious peaks of relative intensity at the wavelength value of 580, 651 and 687 nm in the TLS of the sample, which correspond respectively to spectra of DOM, and the Raman scattering of water and Chl-a in the water. Then the spectral fluorescence signature (SFS) technique was adopted to analyze and distinguish spectral characteristics of DOM and Chl-a in natural water. The calibration curves and function expressions, which indicate the relation between the normalized fluorescence intensities of DOM and Chl-a in water and their concentrations, were obtained respectively under the condition of low concentration(< 40 mg x L(-1))by using normalization of Raman scattering spectrum of water. The curves have a high linearity. When the concentration of the solution with humic acid is large (> 40 mg x L(-1)), the Raman scattering signal is totally absorbed by the molecules of humic acid being on the ground state, so the normalization technique can not be adopted. However the function expression between the concentration of the solution with humic acid and its relative fluorescence peak intensity can be acquired directly with the aid of experiment of fluorescence spectrum. It is concluded that although the expression is non-linearity as a whole, there is a excellent linear relation between the fluorescence intensity and concentration of DOM when the concentration is less than 200 mg x L(-1). The method of measurement based on spectral fluorescence signature technique and the calibration curves gained will have prospects of broad application. It can recognize fast what pollutants are and detect quantitatively their contents in water. It is realizable to monitor the quality of natural water with real time, dynamics and inlarge area.
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Azadioxatriangulenium: a long fluorescence lifetime fluorophore for large biomolecule binding assay
NASA Astrophysics Data System (ADS)
Just Sørensen, Thomas; Thyrhaug, Erling; Szabelski, Mariusz; Luchowski, Rafal; Gryczynski, Ignacy; Gryczynski, Zygmunt; Laursen, Bo W.
2013-06-01
Of the many optical bioassays available, sensing by fluorescence anisotropy has great advantages as it provides a sensitive, instrumentally simple, ratiometric method of detection. However, it is hampered by a severe limitation, as the emission lifetime of the label needs to be comparable to the correlation lifetime (tumbling time) of the biomolecule which is labelled. For proteins of moderate size this is on the order of 20-200 ns, which due to practical issues currently limits the choice of labels to the dansyl-type dyes and certain aromatic dyes. These have the significant drawback of UV/blue absorption and emission as well as an often significant solvent sensitivity. Here, we report the synthesis and characterization of a new fluorescent label for high molecular weight biomolecule assay based on the azadioxatriangulenium motif. The NHS ester of the long fluorescence lifetime, red-emitting fluorophore: azadioxatriangulenium (ADOTA-NHS) was conjugated to anti-rabbit Immunoglobulin G (antiIgG). The long fluorescence lifetime was exploited to determine the correlation time of the high molecular weight antibody and its complex with rabbit Immunoglobulin G (IgG) with steady-state fluorescence anisotropy and time-resolved methods: solution phase immuno-assay was performed following either steady-state or time-resolved fluorescence anisotropy. By performing a variable temperature experiment it was determined that the binding of the ligand resulted in an increase in correlation time of more than 75%, and an increase in the steady-state anisotropy of 18%. The results show that the triangulenium class of dyes can be used in anisotropy assay to detect binding events involving biomolecules of far larger size than what is possible with most other red-emitting organic dyes.
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Valdés, Pablo A.; Leblond, Frederic; Kim, Anthony; Harris, Brent T.; Wilson, Brian C.; Fan, Xiaoyao; Tosteson, Tor D.; Hartov, Alex; Ji, Songbai; Erkmen, Kadir; Simmons, Nathan E.; Paulsen, Keith D.; Roberts, David W.
2011-01-01
Object Accurate discrimination between tumor and normal tissue is crucial for optimal tumor resection. Qualitative fluorescence of protoporphyrin IX (PpIX), synthesized endogenously following δ-aminolevulinic acid (ALA) administration, has been used for this purpose in high-grade glioma (HGG). The authors show that diagnostically significant but visually imperceptible concentrations of PpIX can be quantitatively measured in vivo and used to discriminate normal from neoplastic brain tissue across a range of tumor histologies. Methods The authors studied 14 patients with diagnoses of low-grade glioma (LGG), HGG, meningioma, and metastasis under an institutional review board–approved protocol for fluorescence-guided resection. The primary aim of the study was to compare the diagnostic capabilities of a highly sensitive, spectrally resolved quantitative fluorescence approach to conventional fluorescence imaging for detection of neoplastic tissue in vivo. Results A significant difference in the quantitative measurements of PpIX concentration occurred in all tumor groups compared with normal brain tissue. Receiver operating characteristic (ROC) curve analysis of PpIX concentration as a diagnostic variable for detection of neoplastic tissue yielded a classification efficiency of 87% (AUC = 0.95, specificity = 92%, sensitivity = 84%) compared with 66% (AUC = 0.73, specificity = 100%, sensitivity = 47%) for conventional fluorescence imaging (p < 0.0001). More than 81% (57 of 70) of the quantitative fluorescence measurements that were below the threshold of the surgeon's visual perception were classified correctly in an analysis of all tumors. Conclusions These findings are clinically profound because they demonstrate that ALA-induced PpIX is a targeting biomarker for a variety of intracranial tumors beyond HGGs. This study is the first to measure quantitative ALA-induced PpIX concentrations in vivo, and the results have broad implications for guidance during resection of intracranial tumors. PMID:21438658
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Is the red fluorescence of dental plaque related to its cariogenicity?
NASA Astrophysics Data System (ADS)
Bittar, Daniela G.; Pontes, Laura Regina A.; Calvo, Ana Flávia B.; Novaes, Tatiane F.; Braga, Mariana M.; Freitas, Patrícia M.; Tabchoury, Cinthia P. M.; Mendes, Fausto M.
2014-06-01
It has been speculated that the red fluorescence emitted by dental plaque could be related to its cariogenicity. To test this hypothesis, we designed this crossover in situ study, with two experimental phases of 14 days each. Seventeen volunteers, wearing a palatal appliance with bovine enamel blocks, were instructed to drip a 20% sucrose solution (experimental group) or purified water (control group) onto the enamel blocks eight times daily. The specimens were removed after 4, 7, 10, and 14 days, and the red fluorescence of dental plaque formed on the enamel blocks was assessed using a quantitative light-induced fluorescence device. After the plaque removal, surface and cross-sectional microhardness tests were performed to assess the mineral loss. The comparisons were made by a multilevel linear regression analysis. We observed a significant increase in the red fluorescence of the dental plaque after longer periods of formation, but this trend was verified in both groups. The mineral loss assessed by the microhardness techniques, contrariwise, showed a significant increase only in the experimental group. In conclusion, the red fluorescence emitted by the dental plaque indicates a mature biofilm, but this fact is not necessarily associated with its cariogenicity.
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Development of rapid techniques to determine in situ phytoplankton nutrient status could facilitate understanding of phytoplankton growth and species succession. Variable fluorescence parameters of phytoplankton communities can be easily and rapidly measured, and changes in param...
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Fluorescent Approaches to High Throughput Crystallography
NASA Technical Reports Server (NTRS)
Pusey, Marc L.; Forsythe, Elizabeth; Achari, Aniruddha
2006-01-01
We have shown that by covalently modifying a subpopulation, less than or equal to 1%, of a macromolecule with a fluorescent probe, the labeled material will add to a growing crystal as a microheterogeneous growth unit. Labeling procedures can be readily incorporated into the final stages of purification, and the presence of the probe at low concentrations does not affect the X-ray data quality or the crystallization behavior. The presence of the trace fluorescent label gives a number of advantages when used with high throughput crystallizations. The covalently attached probe will concentrate in the crystal relative to the solution, and under fluorescent illumination crystals show up as bright objects against a dark background. Non-protein structures, such as salt crystals, will not incorporate the probe and will not show up under fluorescent illumination. Brightly fluorescent crystals are readily found against less bright precipitated phases, which under white light illumination may obscure the crystals. Automated image analysis to find crystals should be greatly facilitated, without having to first define crystallization drop boundaries as the protein or protein structures is all that shows up. Fluorescence intensity is a faster search parameter, whether visually or by automated methods, than looking for crystalline features. We are now testing the use of high fluorescence intensity regions, in the absence of clear crystalline features or "hits", as a means for determining potential lead conditions. A working hypothesis is that kinetics leading to non-structured phases may overwhelm and trap more slowly formed ordered assemblies, which subsequently show up as regions of brighter fluorescence intensity. Preliminary experiments with test proteins have resulted in the extraction of a number of crystallization conditions from screening outcomes based solely on the presence of bright fluorescent regions. Subsequent experiments will test this approach using a wider range of proteins. The trace fluorescently labeled crystals will also emit with sufficient intensity to aid in the automation of crystal alignment using relatively low cost optics, further increasing throughput at synchrotrons.
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Spectral Neugebauer-based color halftone prediction model accounting for paper fluorescence.
Hersch, Roger David
2014-08-20
We present a spectral model for predicting the fluorescent emission and the total reflectance of color halftones printed on optically brightened paper. By relying on extended Neugebauer models, the proposed model accounts for the attenuation by the ink halftones of both the incident exciting light in the UV wavelength range and the emerging fluorescent emission in the visible wavelength range. The total reflectance is predicted by adding the predicted fluorescent emission relative to the incident light and the pure reflectance predicted with an ink-spreading enhanced Yule-Nielsen modified Neugebauer reflectance prediction model. The predicted fluorescent emission spectrum as a function of the amounts of cyan, magenta, and yellow inks is very accurate. It can be useful to paper and ink manufacturers who would like to study in detail the contribution of the fluorescent brighteners and the attenuation of the fluorescent emission by ink halftones.
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Fluorescence lifetime imaging and Fourier transform infrared spectroscopy of Michelangelo's David.
Comelli, Daniela; Valentini, Gianluca; Cubeddu, Rinaldo; Toniolo, Lucia
2005-09-01
We developed a combined procedure for the analysis of works of art based on a portable system for fluorescence imaging integrated with analytical measurements on microsamples. The method allows us to localize and identify organic and inorganic compounds present on the surface of artworks. The fluorescence apparatus measures the temporal and spectral features of the fluorescence emission, excited by ultraviolet (UV) laser pulses. The kinetic of the emission is studied through a fluorescence lifetime imaging system, while an optical multichannel analyzer measures the fluorescence spectra of selected points. The chemical characterization of the compounds present on the artistic surfaces is then performed by means of analytical measurements on microsamples collected with the assistance of the fluorescence maps. The previous concepts have been successfully applied to study the contaminants on the surface of Michelangelo's David. The fluorescence analysis combined with Fourier transform infrared (FT-IR) measurements revealed the presence of beeswax, which permeates most of the statue surface, and calcium oxalate deposits mainly arranged in vertical patterns and related to rain washing.
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Fluorescence tomography characterization for sub-surface imaging with protoporphyrin IX
Kepshire, Dax; Davis, Scott C.; Dehghani, Hamid; Paulsen, Keith D.; Pogue, Brian W.
2009-01-01
Optical imaging of fluorescent objects embedded in a tissue simulating medium was characterized using non-contact based approaches to fluorescence remittance imaging (FRI) and sub-surface fluorescence diffuse optical tomography (FDOT). Using Protoporphyrin IX as a fluorescent agent, experiments were performed on tissue phantoms comprised of typical in-vivo tumor to normal tissue contrast ratios, ranging from 3.5:1 up to 10:1. It was found that tomographic imaging was able to recover interior inclusions with high contrast relative to the background; however, simple planar fluorescence imaging provided a superior contrast to noise ratio. Overall, FRI performed optimally when the object was located on or close to the surface and, perhaps most importantly, FDOT was able to recover specific depth information about the location of embedded regions. The results indicate that an optimal system for localizing embedded fluorescent regions should combine fluorescence reflectance imaging for high sensitivity and sub-surface tomography for depth detection, thereby allowing more accurate localization in all three directions within the tissue. PMID:18545571
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Magney, Troy S; Frankenberg, Christian; Fisher, Joshua B; Sun, Ying; North, Gretchen B; Davis, Thomas S; Kornfeld, Ari; Siebke, Katharina
2017-09-01
Recent advances in the retrieval of Chl fluorescence from space using passive methods (solar-induced Chl fluorescence, SIF) promise improved mapping of plant photosynthesis globally. However, unresolved issues related to the spatial, spectral, and temporal dynamics of vegetation fluorescence complicate our ability to interpret SIF measurements. We developed an instrument to measure leaf-level gas exchange simultaneously with pulse-amplitude modulation (PAM) and spectrally resolved fluorescence over the same field of view - allowing us to investigate the relationships between active and passive fluorescence with photosynthesis. Strongly correlated, slope-dependent relationships were observed between measured spectra across all wavelengths (F λ , 670-850 nm) and PAM fluorescence parameters under a range of actinic light intensities (steady-state fluorescence yields, F t ) and saturation pulses (maximal fluorescence yields, F m ). Our results suggest that this method can accurately reproduce the full Chl emission spectra - capturing the spectral dynamics associated with changes in the yields of fluorescence, photochemical (ΦPSII), and nonphotochemical quenching (NPQ). We discuss how this method may establish a link between photosynthetic capacity and the mechanistic drivers of wavelength-specific fluorescence emission during changes in environmental conditions (light, temperature, humidity). Our emphasis is on future research directions linking spectral fluorescence to photosynthesis, ΦPSII, and NPQ. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.
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Santos, Angélica Rossotti Dos; Usso, Mariana Campaner; Gouveia, Juceli Gonzalez; Araya-Jaime, Cristian; Frantine-Silva, Wilson; Giuliano-Caetano, Lucia; Foresti, Fausto; Dias, Ana Lúcia
2017-06-01
The mapping of repetitive DNA sites by fluorescence in situ hybridization has been widely used for karyotype studies in different species of fish, especially when dealing with related species or even genera presenting high chromosome variability. This study analyzed three populations of Bryconamericus, with diploid number preserved, but with different karyotype formulae. Bryconamericus ecai, from the Forquetinha river/RS, presented three new cytotypes, increasing the number of karyotype forms to seven in this population. Other two populations of Bryconamericus sp. from the Vermelho stream/PR and Cambuta river/PR exhibited interpopulation variation. The chromosome mapping of rDNA sites revealed unique markings among the three populations, showing inter- and intrapopulation variability located in the terminal region. The molecular analysis using DNA barcoding complementing the cytogenetic analysis also showed differentiation among the three populations. The U2 small nuclear DNA repetitive sequence exhibited conserved features, being located in the interstitial region of a single chromosome pair. This is the first report on its occurrence in the genus Bryconamericus. Data obtained revealed a karyotype variability already assigned to the genus, along with polymorphism of ribosomal sites, demonstrating that this group of fish can be undergoing a divergent evolutionary process, constituting a substantive model for studies of chromosomal evolution.
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Zhang, Yaobin; Liu, Yiwen; Jing, Yanwen; Zhao, Zhiqiang; Quan, Xie
2012-01-01
Zero valent iron (ZVI) is expected to help create an enhanced anaerobic environment that might improve the performance of anaerobic treatment. Based on this idea, a novel ZVI packed upflow anaerobic sludge blanket (ZVI-UASB) reactor was developed to treat azo dye wastewater with variable influent quality. The results showed that the reactor was less influenced by increases of Reactive Brilliant Red X-3B concentration from 50 to 1000 mg/L and chemical oxygen demand (COD) from 1000 to 7000 mg/L in the feed than a reference UASB reactor without the ZVI. The ZVI decreased oxidation-reduction potential in the reactor by about 80 mV. Iron ion dissolution from the ZVI could buffer acidity in the reactor, the amount of which was related to the COD concentration. Fluorescence in situ hybridization test showed the abundance of methanogens in the sludge of the ZVI-UASB reactor was significantly greater than that of the reference one. Denaturing gradient gel electrophoresis showed that the ZVI increased the diversity of microbial strains responsible for high efficiency.
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The Origin of Fluorescence from Graphene Oxide
Shang, Jingzhi; Ma, Lin; Li, Jiewei; Ai, Wei; Yu, Ting; Gurzadyan, Gagik G.
2012-01-01
Time-resolved fluorescence measurements of graphene oxide in water show multiexponential decay kinetics ranging from 1 ps to 2 ns. Electron-hole recombination from the bottom of the conduction band and nearby localized states to wide-range valance band is suggested as origin of the fluorescence. Excitation wavelength dependence of the fluorescence was caused by relative intensity changes of few emission species. By introducing the molecular orbital concept, the dominant fluorescence was found to originate from the electronic transitions among/between the non-oxidized carbon regions and the boundary of oxidized carbon atom regions, where all three kinds of functionalized groups C-O, C = O and O = C-OH were participating. In the visible spectral range, the ultrafast fluorescence of graphene oxide was observed for the first time. PMID:23145316
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Wang, Lei; Li, Baoqiang; Xu, Feng; Li, Ying; Xu, Zheheng; Wei, Daqing; Feng, Yujie; Wang, Yaming; Jia, Dechang; Zhou, Yu
2017-11-01
Visual in vivo degradation of hydrogel by fluorescence-related tracking and monitoring is crucial for quantitatively depicting the degradation profile of hydrogel in a real-time and non-invasive manner. However, the commonly used fluorescent imaging usually encounters limitations, such as intrinsic photobleaching of organic fluorophores and uncertain perturbation of degradation induced by the change in molecular structure of hydrogel. To address these problems, we employed photoluminescent carbon nanodots (CNDs) with low photobleaching, red emission and good biocompatibility as fluorescent indicator for real-time and non-invasive visual in vitro/in vivo degradation of injectable hydrogels that are mixed with CNDs. The in vitro/in vivo toxicity results suggested that CNDs were nontoxic. The embedded CNDs in hydrogels did not diffuse outside in the absence of hydrogel degradation. We had acquired similar degradation kinetics (PBS-Enzyme) between gravimetric and visual determination, and established mathematical equation to quantitatively depict in vitro degradation profile of hydrogels for the predication of in vivo hydrogel degradation. Based on the in vitro data, we developed a visual platform that could quantitatively depict in vivo degradation behavior of new injectable biomaterials by real-time and non-invasive fluorescence tracking. This fluorescence-related visual imaging methodology could be applied to subcutaneous degradation of injectable hydrogel with down to 7 mm depth in small animal trials so far. This fluorescence-related visual imaging methodology holds great potentials for rational design and convenient in vivo screening of biocompatible and biodegradable injectable hydrogels in tissue engineering. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Cohen, Sarit; Pellach, Michal; Kam, Yossi; Grinberg, Igor; Corem-Salkmon, Enav; Rubinstein, Abraham; Margel, Shlomo
2013-03-01
Near IR (NIR) fluorescent human serum albumin (HSA) nanoparticles hold great promise as contrast agents for tumor diagnosis. HSA nanoparticles are considered to be biocompatible, non-toxic and non-immunogenic. In addition, NIR fluorescence properties of these nanoparticles are important for in vivo tumor diagnostics, with low autofluorescence and relatively deep penetration of NIR irradiation due to low absorption of biomatrices. The present study describes the synthesis of new NIR fluorescent HSA nanoparticles, by entrapment of a NIR fluorescent dye within the HSA nanoparticles, which also significantly increases the photostability of the dye. Tumor-targeting ligands such as peanut agglutinin (PNA) and anti-carcinoembryonic antigen antibodies (anti-CEA) were covalently conjugated to the NIR fluorescent albumin nanoparticles, increasing the potential fluorescent signal in tumors with upregulated corresponding receptors. Specific colon tumor detection by the NIR fluorescent HSA nanoparticles was demonstrated in a chicken embryo model and a rat model. In future work we also plan to encapsulate cancer drugs such as doxorubicin within the NIR fluorescent HSA nanoparticles for both colon cancer imaging and therapy. Copyright © 2012 Elsevier B.V. All rights reserved.
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NASA Astrophysics Data System (ADS)
Sun, Jessica; Miller, Jessica P.; Hathi, Deep; Zhou, Haiying; Achilefu, Samuel; Shokeen, Monica; Akers, Walter J.
2016-08-01
Fluorescence imaging, in combination with tumor-avid near-infrared (NIR) fluorescent molecular probes, provides high specificity and sensitivity for cancer detection in preclinical animal models, and more recently, assistance during oncologic surgery. However, conventional camera-based fluorescence imaging techniques are heavily surface-weighted such that surface reflection from skin or other nontumor tissue and nonspecific fluorescence signals dominate, obscuring true cancer-specific signals and blurring tumor boundaries. To address this challenge, we applied structured illumination fluorescence molecular imaging (SIFMI) in live animals for automated subtraction of nonspecific surface signals to better delineate accumulation of an NIR fluorescent probe targeting α4β1 integrin in mice bearing subcutaneous plasma cell xenografts. SIFMI demonstrated a fivefold improvement in tumor-to-background contrast when compared with other full-field fluorescence imaging methods and required significantly reduced scanning time compared with diffuse optical spectroscopy imaging. Furthermore, the spatial gradient mapping enhanced highlighting of tumor boundaries. Through the relatively simple hardware and software modifications described, SIFMI can be integrated with clinical fluorescence imaging systems, enhancing intraoperative tumor boundary delineation from the uninvolved tissue.
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NASA Astrophysics Data System (ADS)
Toury, Marion; Chandler, Lin; Allison, Archie; Campbell, David; McLoskey, David; Holmes-Smith, A. Sheila; Hungerford, Graham
2011-03-01
Fluorescence microscopy provides a non-invasive means for visualising dynamic protein interactions. As well as allowing the calculation of kinetic processes via the use of time-resolved fluorescence, localisation of the protein within cells or model systems can be monitored. These fluorescence lifetime images (FLIM) have become the preferred technique for elucidating protein dynamics due to the fact that the fluorescence lifetime is an absolute measure, in the main independent of fluorophore concentration and intensity fluctuations caused by factors such as photobleaching. In this work we demonstrate the use of a time-resolved fluorescence microscopy, employing a high repetition rate laser excitation source applied to study the influence of a metal surface on fluorescence tagged protein and to elucidate viscosity using the fluorescence lifetime probe DASPMI. These were studied in a cellular environment (yeast) and in a model system based on a sol-gel derived material, in which silver nanostructures were formed in situ using irradiation from a semiconductor laser in CW mode incorporated on a compact time-resolved fluorescence microscope (HORIBA Scientific DeltaDiode and DynaMyc).
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Fluorescent filtered electrophosphorescence
Forrest, Stephen; Sun, Yiru; Giebink, Noel; Thompson, Mark E.
2010-08-03
The present invention relates to organic light emitting devices (OLEDs), and more specifically to OLEDS that emit light using a combination of fluorescent emitters and phosphorescent emitters for the efficient utilization of all of the electrically generated excitons.
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Fluorescent filtered electrophosphorescence
Forrest, Stephen R [Princeton, NJ; Sun, Yiru [Princeton, NJ; Giebink, Noel [Princeton, NJ; Thompson, Mark E [Anaheim Hills, CA
2009-01-06
The present invention relates to organic light emitting devices (OLEDs), and more specifically to OLEDS that emit light using a combination of fluorescent emitters and phosphorescent emitters for the efficient utilization of all of the electrically generated excitons.
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Fluorescence kinetics of emission from a small finite volume of a biological system
NASA Astrophysics Data System (ADS)
Dagen, A. J.; Alfano, R. R.; Zilinskas, B. A.; Swenberg, C. E.
1985-07-01
The fluorescence decay, apparent quantum yield and transmission from chromophores constrained to a microscopic volume using a single picosecond laser excitation were measured as a function of incident intensity. The β subunit of phycoeryhthrin aggregate isolated from the photosynthetic antenna system of Nostoc sp. was selected since it contains only four chromophores in a volume of less than 5.6×10 4 Å 3. The non-exponential fluorescence decay profiles were intensity independent for the intensity range studied (5 × 10 13 - 2 × 10 15 photon cm -2 per pulse). The apparent decrease in the relative fluorescence quantum yield and increase of the relative transmission with increasing excitation intensity is attributed to the combined effects of ground state depletion and upper excited state absorption. Evidence suggests that exciton annihilation is absent within isolated β subunits.
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Early remote laser detection of vegetation damage caused by certain environmental stress factors
NASA Technical Reports Server (NTRS)
Chappelle, Emmett W.; Mcmurtrey, James E., III
1989-01-01
The fluorescence spectra of plants excited with a pulsed nitrogen laser beam emitting at 337 nm were found to be related to plant type, as well as with changes in the physiology of the plant as the result of various kinds of environmental stress. The plant types which were studied included herbaceous dicots, monocots, hardwoods, and conifers. These plant types could be identified on the basis of differences in either the number of fluorescent bands, or the relative intensity of the bands. The dicots and monocots had fluorescent maxima at 440, 685, and 740 nm. The monocots could be distinguished from the dicots by virtue of having a much higher 440 nm/685 nm ratio. Hardwoods and conifers had an additional fluorescence band at 525 nm, but healthy conifers did not have a band at 685 nm.
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NASA Technical Reports Server (NTRS)
Dobson, Chris C.
1998-01-01
Sodium fluorescence induced by a narrow bandwidth tunable laser has been used to measure temperature, pressure, axial velocity and species concentrations in wind tunnels, rocket engine exhausts and the upper atmosphere. Optical pumping of the ground states of the sodium, however, can radically alter the shape of the laser induced fluorescence excitation spectrum, complicating such measurements. Here a straightforward extension of rate equations originally proposed to account for the features of the pumped spectrum is to make temperature measurements from spectra taken in pumped vapor. Also determined from the spectrum is the relative fluorescence cycle number, which has application to measurement of diffusion rate and transverse flow velocity. The accuracy of both the temperature and cycle-number measurements is comparable with that of temperature measurements made in the absence of pumping.
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Bertoncini, E I; D'Orazio, V; Senesi, N; Mattiazzo, M E
2005-03-01
Conventional monodimensional fluorescence spectroscopy in the emission, excitation, and synchronous-scan modes and total luminescence spectroscopy have proven to be sensitive techniques for characterization and differentiation of humic acid (HA) and fulvic acid (FA) fractions isolated from an aerobically and anaerobically digested and limed biosolid, two layers of a sandy and a clayey Brazilian oxisol, and the corresponding biosolid-amended soils. The spectral patterns and the relative fluorescence intensities suggest greater molecular heterogeneity, less aromatic polycondensation, and less humification of biosolid HA and FA compared with soil HA and FA. However, the differences are smaller for the FA fractions than for the HA fractions. Fluorescence properties of soil HA and FA differ slightly as a function of soil type and soil layer. Biosolid application causes a shift to shorter wavelengths of the main fluorescence peaks and marked variation of the relative fluorescence intensities of HA and FA isolated from amended soils. These results suggest that molecular components of relatively small molecular size, with a low level of aromatic polycondensation, and low degree of humification present in biosolid HA and FA are partially and variously incorporated into amended soil HA and FA. In general, these modifications seem to be smaller in HA and FA from the clayey soil layers than in those from the sandy soil layers, possibly because of protective effects exerted by clay minerals of native soil HA and FA against disturbances caused by biosolid application.
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NASA Astrophysics Data System (ADS)
Schweitzer, Dietrich; Schweitzer, Frank; Hammer, Martin; Schenke, Stefan; Richter, Sandra
2005-08-01
Age-related macular degeneration (AMD) is the most frequent cause for blindness for person older than 65 years in western countries. Besides the subjective pain, it is also an economic problem in the ageing population. As the pathomechanism is unknown, no curative treatment is possible. International research for discovering of early age-related alterations at the fundus is directed on in vivo measurements of autofluorescence. One way is the measurement of fluorescence spectra. Unfortunately, any selective excitation of fluorophores is excluded by the absorption edge of the ocular media at 400 nm. Furthermore, the shape of fluorescence spectra is influenced by the spectral absorption of layers in front of the emitting fluorophore. Weakly emitting fluorophores are covered by intensive emitting substances. The most serious limitation in fluorescence measurements of the living human fundus is the maximal permissible exposure. For that reason, fluorescence spectra of the fundus can not be detected with a high spatial resolution. The detection of dynamic fluorescence provides substance-specific lifetimes Ti, amplitudes Ai, and information about the relative contribution Qi of components in fluorescence images. As these parameters are calculated for each image point, diagrams of Ti vs. Tj, Ai vs. Aj, and Qi vs. Qj can be drawn, in which specific clusters appear for healthy subjects or AMD - patients. The projection of lifetime - clusters onto corresponding axis represents histogram of the considered lifetime. The slope in the correlation between Ai and Aj can also be used as a discriminating mark. Considering image lines as intersection through characteristic anatomical structures (optic disc, macula) profiles of Ti, Ai, or Qi show changes of these parameters (e.g. depigmentation) as function of location, which might be specific for AMD.
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Hirschfeld, T.B.
1985-09-24
Method and apparatus are provided for measuring temperature and for generating optical signals related to temperature. Light from a fiber optic is directed to a material whose fluorescent response varies with ambient temperature. The same fiber optic delivering the excitation beam also collects a portion of the fluorescent emission for analysis. Signal collection efficiency of the fiber optic is enhanced by requiring that the fluorescent probe material be in the shape of an oblong parabolically tapered solid. Reproducibility is enhanced by using Raman backscatter to monitor excitation beam fluctuations, and by using measurements of fluorescence lifetime. 10 figs.
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Preparation and flow cytometry of uniform silica-fluorescent dye microspheres.
Bele, Marjan; Siiman, Olavi; Matijević, Egon
2002-10-15
Uniform fluorescent silica-dye microspheres have been prepared by coating preformed monodispersed silica particles with silica layers containing rhodamine 6G or acridine orange. The resulting dispersions exhibit intense fluorescent emission between 500 and 600 nm, over a broad excitation wavelength range of 460 to 550 nm, even with exceedingly small amounts of dyes incorporated into the silica particles (10-30 ppm, expressed as weight of dye relative to weight of dry particles). The fluorescent particles can be prepared in micrometer diameters suitable for analyses using flow cytometry with 488-nm laser excitation.
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Fluorescence errors in integrating sphere measurements of remote phosphor type LED light sources
NASA Astrophysics Data System (ADS)
Keppens, A.; Zong, Y.; Podobedov, V. B.; Nadal, M. E.; Hanselaer, P.; Ohno, Y.
2011-05-01
The relative spectral radiant flux error caused by phosphor fluorescence during integrating sphere measurements is investigated both theoretically and experimentally. Integrating sphere and goniophotometer measurements are compared and used for model validation, while a case study provides additional clarification. Criteria for reducing fluorescence errors to a degree of negligibility as well as a fluorescence error correction method based on simple matrix algebra are presented. Only remote phosphor type LED light sources are studied because of their large phosphor surfaces and high application potential in general lighting.
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Method for remote detection of trace contaminants
Simonson, Robert J.; Hance, Bradley G.
2003-09-09
A method for remote detection of trace contaminants in a target area comprises applying sensor particles that preconcentrate the trace contaminant to the target area and detecting the contaminant-sensitive fluorescence from the sensor particles. The sensor particles can have contaminant-sensitive and contaminant-insensitive fluorescent compounds to enable the determination of the amount of trace contaminant present in the target are by relative comparison of the emission of the fluorescent compounds by a local or remote fluorescence detector. The method can be used to remotely detect buried minefields.
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Hirschfeld, Tomas B.
1985-01-01
Method and apparatus are provided for measuring temperature and for generating optical signals related to temperature. Light from a fiber optic is directed to a material whose fluorescent response varies with ambient temperature. The same fiber optic delivering the excitation beam also collects a portion of the fluorescent emission for analysis. Signal collection efficiency of the fiber optic is enhanced by requiring that the fluorescent probe material be in the shape of an oblong parabolically tapered solid. Reproducibility is enhanced by using Raman backscatter to monitor excitation beam fluctuations, and by using measurements of fluorescence lifetime.
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Imamura, Ryota; Murata, Naoki; Shimanouchi, Toshinori; Yamashita, Kaoru; Fukuzawa, Masayuki; Noda, Minoru
2017-01-01
A new fluorescent arrayed biosensor has been developed to discriminate species and concentrations of target proteins by using plural different phospholipid liposome species encapsulating fluorescent molecules, utilizing differences in permeation of the fluorescent molecules through the membrane to modulate liposome-target protein interactions. This approach proposes a basically new label-free fluorescent sensor, compared with the common technique of developed fluorescent array sensors with labeling. We have confirmed a high output intensity of fluorescence emission related to characteristics of the fluorescent molecules dependent on their concentrations when they leak from inside the liposomes through the perturbed lipid membrane. After taking an array image of the fluorescence emission from the sensor using a CMOS imager, the output intensities of the fluorescence were analyzed by a principal component analysis (PCA) statistical method. It is found from PCA plots that different protein species with several concentrations were successfully discriminated by using the different lipid membranes with high cumulative contribution ratio. We also confirmed that the accuracy of the discrimination by the array sensor with a single shot is higher than that of a single sensor with multiple shots. PMID:28714873
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Imamura, Ryota; Murata, Naoki; Shimanouchi, Toshinori; Yamashita, Kaoru; Fukuzawa, Masayuki; Noda, Minoru
2017-07-15
A new fluorescent arrayed biosensor has been developed to discriminate species and concentrations of target proteins by using plural different phospholipid liposome species encapsulating fluorescent molecules, utilizing differences in permeation of the fluorescent molecules through the membrane to modulate liposome-target protein interactions. This approach proposes a basically new label-free fluorescent sensor, compared with the common technique of developed fluorescent array sensors with labeling. We have confirmed a high output intensity of fluorescence emission related to characteristics of the fluorescent molecules dependent on their concentrations when they leak from inside the liposomes through the perturbed lipid membrane. After taking an array image of the fluorescence emission from the sensor using a CMOS imager, the output intensities of the fluorescence were analyzed by a principal component analysis (PCA) statistical method. It is found from PCA plots that different protein species with several concentrations were successfully discriminated by using the different lipid membranes with high cumulative contribution ratio. We also confirmed that the accuracy of the discrimination by the array sensor with a single shot is higher than that of a single sensor with multiple shots.
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An overview of remote sensing of chlorophyll fluorescence
NASA Astrophysics Data System (ADS)
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.
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Image navigation as a means to expand the boundaries of fluorescence-guided surgery
NASA Astrophysics Data System (ADS)
Brouwer, Oscar R.; Buckle, Tessa; Bunschoten, Anton; Kuil, Joeri; Vahrmeijer, Alexander L.; Wendler, Thomas; Valdés-Olmos, Renato A.; van der Poel, Henk G.; van Leeuwen, Fijs W. B.
2012-05-01
Hybrid tracers that are both radioactive and fluorescent help extend the use of fluorescence-guided surgery to deeper structures. Such hybrid tracers facilitate preoperative surgical planning using (3D) scintigraphic images and enable synchronous intraoperative radio- and fluorescence guidance. Nevertheless, we previously found that improved orientation during laparoscopic surgery remains desirable. Here we illustrate how intraoperative navigation based on optical tracking of a fluorescence endoscope may help further improve the accuracy of hybrid surgical guidance. After feeding SPECT/CT images with an optical fiducial as a reference target to the navigation system, optical tracking could be used to position the tip of the fluorescence endoscope relative to the preoperative 3D imaging data. This hybrid navigation approach allowed us to accurately identify marker seeds in a phantom setup. The multispectral nature of the fluorescence endoscope enabled stepwise visualization of the two clinically approved fluorescent dyes, fluorescein and indocyanine green. In addition, the approach was used to navigate toward the prostate in a patient undergoing robot-assisted prostatectomy. Navigation of the tracked fluorescence endoscope toward the target identified on SPECT/CT resulted in real-time gradual visualization of the fluorescent signal in the prostate, thus providing an intraoperative confirmation of the navigation accuracy.
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NASA Astrophysics Data System (ADS)
Carbary-Ganz, Jordan L.; Welge, Weston A.; Barton, Jennifer K.; Utzinger, Urs
2015-09-01
Optical coherence tomography/laser induced fluorescence (OCT/LIF) dual-modality imaging allows for minimally invasive, nondestructive endoscopic visualization of colorectal cancer in mice. This technology enables simultaneous longitudinal tracking of morphological (OCT) and biochemical (fluorescence) changes as colorectal cancer develops, compared to current methods of colorectal cancer screening in humans that rely on morphological changes alone. We have shown that QDot655 targeted to vascular endothelial growth factor receptor 2 (QD655-VEGFR2) can be applied to the colon of carcinogen-treated mice and provides significantly increased contrast between the diseased and undiseased tissue with high sensitivity and specificity ex vivo. QD655-VEGFR2 was used in a longitudinal in vivo study to investigate the ability to correlate fluorescence signal to tumor development. QD655-VEGFR2 was applied to the colon of azoxymethane (AOM-) or saline-treated control mice in vivo via lavage. OCT/LIF images of the distal colon were taken at five consecutive time points every three weeks after the final AOM injection. Difficulties in fully flushing unbound contrast agent from the colon led to variable background signal; however, a spatial correlation was found between tumors identified in OCT images, and high fluorescence intensity of the QD655 signal, demonstrating the ability to detect VEGFR2 expressing tumors in vivo.
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NASA Astrophysics Data System (ADS)
Gharekhan, Anita H.; Biswal, Nrusingh C.; Gupta, Sharad; Pradhan, Asima; Sureshkumar, M. B.; Panigrahi, Prasanta K.
2008-02-01
The statistical and characteristic features of the polarized fluorescence spectra from cancer, normal and benign human breast tissues are studied through wavelet transform and singular value decomposition. The discrete wavelets enabled one to isolate high and low frequency spectral fluctuations, which revealed substantial randomization in the cancerous tissues, not present in the normal cases. In particular, the fluctuations fitted well with a Gaussian distribution for the cancerous tissues in the perpendicular component. One finds non-Gaussian behavior for normal and benign tissues' spectral variations. The study of the difference of intensities in parallel and perpendicular channels, which is free from the diffusive component, revealed weak fluorescence activity in the 630nm domain, for the cancerous tissues. This may be ascribable to porphyrin emission. The role of both scatterers and fluorophores in the observed minor intensity peak for the cancer case is experimentally confirmed through tissue-phantom experiments. Continuous Morlet wavelet also highlighted this domain for the cancerous tissue fluorescence spectra. Correlation in the spectral fluctuation is further studied in different tissue types through singular value decomposition. Apart from identifying different domains of spectral activity for diseased and non-diseased tissues, we found random matrix support for the spectral fluctuations. The small eigenvalues of the perpendicular polarized fluorescence spectra of cancerous tissues fitted remarkably well with random matrix prediction for Gaussian random variables, confirming our observations about spectral fluctuations in the wavelet domain.
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What limits photosynthetic energy conversion efficiency in nature? Lessons from the oceans.
Falkowski, Paul G; Lin, Hanzhi; Gorbunov, Maxim Y
2017-09-26
Constraining photosynthetic energy conversion efficiency in nature is challenging. In principle, two yield measurements must be made simultaneously: photochemistry, fluorescence and/or thermal dissipation. We constructed two different, extremely sensitive and precise active fluorometers: one measures the quantum yield of photochemistry from changes in variable fluorescence, the other measures fluorescence lifetimes in the picosecond time domain. By deploying the pair of instruments on eight transoceanic cruises over six years, we obtained over 200 000 measurements of fluorescence yields and lifetimes from surface waters in five ocean basins. Our results revealed that the average quantum yield of photochemistry was approximately 0.35 while the average quantum yield of fluorescence was approximately 0.07. Thus, closure on the energy budget suggests that, on average, approximately 58% of the photons absorbed by phytoplankton in the world oceans are dissipated as heat. This extraordinary inefficiency is associated with the paucity of nutrients in the upper ocean, especially dissolved inorganic nitrogen and iron. Our results strongly suggest that, in nature, most of the time, most of the phytoplankton community operates at approximately half of its maximal photosynthetic energy conversion efficiency because nutrients limit the synthesis or function of essential components in the photosynthetic apparatus.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'. © 2017 The Author(s).
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Murphy, Kathleen R.; Butler, Kenna D.; Spencer, Robert G. M.; Stedmon, Colin A.; Boehme, Jennifer R.; Aiken, George R.
2010-01-01
The fluorescent properties of dissolved organic matter (DOM) are often studied in order to infer DOM characteristics in aquatic environments, including source, quantity, composition, and behavior. While a potentially powerful technique, a single widely implemented standard method for correcting and presenting fluorescence measurements is lacking, leading to difficulties when comparing data collected by different research groups. This paper reports on a large-scale interlaboratory comparison in which natural samples and well-characterized fluorophores were analyzed in 20 laboratories in the U.S., Europe, and Australia. Shortcomings were evident in several areas, including data quality-assurance, the accuracy of spectral correction factors used to correct EEMs, and the treatment of optically dense samples. Data corrected by participants according to individual laboratory procedures were more variable than when corrected under a standard protocol. Wavelength dependency in measurement precision and accuracy were observed within and between instruments, even in corrected data. In an effort to reduce future occurrences of similar problems, algorithms for correcting and calibrating EEMs are described in detail, and MATLAB scripts for implementing the study's protocol are provided. Combined with the recent expansion of spectral fluorescence standards, this approach will serve to increase the intercomparability of DOM fluorescence studies.
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Galievsky, Victor A; Stasheuski, Alexander S; Krylov, Sergey N
2017-10-17
The limit-of-detection (LOD) in analytical instruments with fluorescence detection can be improved by reducing noise of optical background. Efficiently reducing optical background noise in systems with spectrally nonuniform background requires complex optimization of an emission filter-the main element of spectral filtration. Here, we introduce a filter-optimization method, which utilizes an expression for the signal-to-noise ratio (SNR) as a function of (i) all noise components (dark, shot, and flicker), (ii) emission spectrum of the analyte, (iii) emission spectrum of the optical background, and (iv) transmittance spectrum of the emission filter. In essence, the noise components and the emission spectra are determined experimentally and substituted into the expression. This leaves a single variable-the transmittance spectrum of the filter-which is optimized numerically by maximizing SNR. Maximizing SNR provides an accurate way of filter optimization, while a previously used approach based on maximizing a signal-to-background ratio (SBR) is the approximation that can lead to much poorer LOD specifically in detection of fluorescently labeled biomolecules. The proposed filter-optimization method will be an indispensable tool for developing new and improving existing fluorescence-detection systems aiming at ultimately low LOD.
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Toluene laser-induced fluorescence imaging of compressible flows in an expansion tube
NASA Astrophysics Data System (ADS)
Miller, V. A.; Gamba, M.; Mungal, M. G.; Hanson, R. K.; Mohri, K.; Schulz, C.
2011-11-01
Laser-induced fluorescence (LIF) imaging using toluene as a tracer molecule has been developed for high-speed, low-to-moderate enthalpy conditions in the Stanford 6-inch Expansion Tube. The approach is demonstrated on three canonical compressible flow configurations: (i) supersonic flow over a 20° wedge, (ii) around a cylinder, and (iii) a supersonic boundary layer. Under constant-pressure conditions, toluene LIF offers unique sensitivity to temperature and can therefore be used as an accurate thermometry diagnostic for supersonic flows; on the other hand, for variable-pressure flow fields (e.g., flow around a blunt body), toluene LIF imaging is demonstrated to be an effective flow visualization tool. The three configurations selected demonstrate the diagnostic in these two capacities. For all configurations considered in the study, toluene (0.6% by volume) is seeded into a nitrogen freestream at a Mach number ~ 2.2, T ~ 500K, and p ~ 1.5 bar. A frequency-quadrupled pulsed Nd:YAG laser is used to excite the tracer, and the resulting fluorescence is captured by an ICCD camera. Synthetic fluorescence signals from CFD solutions of each case have been computed and compare favorably to measured signals. Sponsored by DoE PSAAP at Stanford University.
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Visualizing photosynthesis through processing of chlorophyll fluorescence images
NASA Astrophysics Data System (ADS)
Daley, Paul F.; Ball, J. Timothy; Berry, Joseph A.; Patzke, Juergen; Raschke, Klaus E.
1990-05-01
Measurements of terrestrial plant photosynthesis frequently exploit sensing of gas exchange from leaves enclosed in gas-tight, climate controlled chambers. These methods are typically slow, and do not resolve variation in photosynthesis below the whole leaf level. A photosynthesis visualization technique is presented that uses images of leaves employing light from chlorophyll (Chl) fluorescence. Images of Chl fluorescence from whole leaves undergoing steady-state photosynthesis, photosynthesis induction, or response to stress agents were digitized during light flashes that saturated photochemical reactions. Use of saturating flashes permitted deconvolution of photochemical energy use from biochemical quenching mechanisms (qN) that dissipate excess excitation energy, otherwise damaging to the light harvesting apparatus. Combination of the digital image frames of variable fluorescence with reference frames obtained from the same leaves when dark-adapted permitted derivation of frames in which grey scale represented the magnitude of qN. Simultaneous measurements with gas-exchange apparatus provided data for non-linear calibration filters for subsequent rendering of grey-scale "images" of photosynthesis. In several experiments significant non-homogeneity of photosynthetic activity was observed following treatment with growth hormones, or shifts in light or humidity, and following infection by virus. The technique provides a rapid, non-invasive probe for stress physiology and plant disease detection.
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NASA Technical Reports Server (NTRS)
Heath, Christopher M.; Anderson, Robert C.; Hicks, Yolanda R.
2011-01-01
Planar laser-induced fluorescence (PLIF) excitation/detection methods have been applied to obtain spatial distributions of the hydroxyl [OH] reacting intermediary and hydrocarbon [HC] primary species in laminar and turbulent combustion reactions. In this report, broadband and narrowband excitation/filtering techniques are explored to identify an optimal experimental configuration yielding significant fluorescent signal with low absorption losses. The combustion environments analyzed include 1) a laminar non-premixed methane/air flame and 2) a turbulent, non-premixed Jet-A/air fueled flame within a lean flame tube combustor. Hydrocarbon-based fuel and OH were excited via the R1 (1), R1(10) and R2(7) transitions of the A(sup 2)Epsilon(+) X(sup 2)pi(1,0) band using a broadband Nd:YAG pumped optical parametric oscillator (OPO) and narrowband Nd:YAG/dye laser with ultraviolet frequency extension (UVX) package. Variables tested for influence on fluorescent signal and absorption characteristics were excitation line, laser energy, exciting linewidth, combustion reactants, and test flow conditions. Results are intended to guide the transition from a dye/UVX laser to an OPO system for performing advanced diagnostics of low-emission combustion concepts.
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Fluorescence imaging to study cancer burden on lymph nodes
NASA Astrophysics Data System (ADS)
D'Souza, Alisha V.; Elliott, Jonathan T.; Gunn, Jason R.; Samkoe, Kimberley S.; Tichauer, Kenneth M.; Pogue, Brian W.
2015-03-01
Morbidity and complexity involved in lymph node staging via surgical resection and biopsy calls for staging techniques that are less invasive. While visible blue dyes are commonly used in locating sentinel lymph nodes, since they follow tumor-draining lymphatic vessels, they do not provide a metric to evaluate presence of cancer. An area of active research is to use fluorescent dyes to assess tumor burden of sentinel and secondary lymph nodes. The goal of this work was to successfully deploy and test an intra-nodal cancer-cell injection model to enable planar fluorescence imaging of a clinically relevant blue dye, specifically methylene blue along with a cancer targeting tracer, Affibody labeled with IRDYE800CW and subsequently segregate tumor-bearing from normal lymph nodes. This direct-injection based tumor model was employed in athymic rats (6 normal, 4 controls, 6 cancer-bearing), where luciferase-expressing breast cancer cells were injected into axillary lymph nodes. Tumor presence in nodes was confirmed by bioluminescence imaging before and after fluorescence imaging. Lymphatic uptake from the injection site (intradermal on forepaw) to lymph node was imaged at approximately 2 frames/minute. Large variability was observed within each cohort.
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Photophysical Characterization of Enhanced 6-Methylisoxanthopterin Fluorescence in Duplex DNA.
Moreno, Andrew; Knee, J L; Mukerji, Ishita
2016-12-08
The structure and dynamic motions of bases in DNA duplexes and other constructs are important for understanding mechanisms of selectivity and recognition of DNA-binding proteins. The fluorescent guanine analogue, 6-methylisoxanthopterin 6-MI, is well suited to this purpose as it exhibits an unexpected 3- to 4-fold increase in relative quantum yield upon duplex formation when incorporated into the following sequences: ATFAA, AAFTA, or ATFTA (where F represents 6-MI). To better understand some of the factors leading to the 6-MI fluorescence increase upon duplex formation, we characterized the effect of local sequence and structural perturbations on 6-MI photophysics through temperature melts, quantum yield measurements, fluorescence quenching assays, and fluorescence lifetime measurements. By examining 21 sequences we have determined that the duplex-enhanced fluorescence (DEF) depends on the composition of bases adjacent to 6-MI and the presence of adenines at locations n ± 2 from the probe. Investigation of duplex stability and local solvent accessibility measurements support a model in which the DEF arises from a constrained geometry of 6-MI in the duplex, which remains H-bonded to cytosine, stacked with adjacent bases and inaccessible to quenchers. Perturbation of DNA structure through the introduction of an unpaired base 3' to 6-MI or a mismatched basepair increases 6-MI dynamic motion leading to fluorescence quenching and a reduction in quantum yield. Molecular dynamics simulations suggest the enhanced fluorescence results from a greater degree of twist at the X-F step relative to the quenched duplexes examined. These results point to a model where adenine residues located at n ± 2 from 6-MI induce a structural geometry with greater twist in the duplex that hinders local motion reducing dynamic quenching and producing an increase in 6-MI fluorescence.
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Luminescence properties of europium?terbium double activated calcium tungstate phosphor*1
NASA Astrophysics Data System (ADS)
Nazarov, M. V.; Jeon, D. Y.; Kang, J. H.; Popovici, E.-J.; Muresan, L.-E.; Zamoryanskaya, M. V.; Tsukerblat, B. S.
2004-08-01
Double incorporation of Eu 3+ and Tb 3+ ions into a CaWO 4 crystalline lattice modifies the luminescence spectrum due to the formation of new emission centers. Depending on the activators concentration and nature, as well as on the interaction between the activators themselves, the luminescence color can be varied within the entire range of the visible spectrum. Variable luminescence was obtained when CaWO 4:Eu,Tb phosphors with 0-5 mol% activator ions were exposed to relatively low excitation energies as UV (365 and 254 nm). Under high energy excitation such as VUV (147 nm) radiation or electron beam, white light has been observed. This material with controlled properties seems to be promising for the applications in fluorescent lamps, colored lightning for advertisement industries, and other optoelectronic devices.
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Rapid Global Fitting of Large Fluorescence Lifetime Imaging Microscopy Datasets
Warren, Sean C.; Margineanu, Anca; Alibhai, Dominic; Kelly, Douglas J.; Talbot, Clifford; Alexandrov, Yuriy; Munro, Ian; Katan, Matilda
2013-01-01
Fluorescence lifetime imaging (FLIM) is widely applied to obtain quantitative information from fluorescence signals, particularly using Förster Resonant Energy Transfer (FRET) measurements to map, for example, protein-protein interactions. Extracting FRET efficiencies or population fractions typically entails fitting data to complex fluorescence decay models but such experiments are frequently photon constrained, particularly for live cell or in vivo imaging, and this leads to unacceptable errors when analysing data on a pixel-wise basis. Lifetimes and population fractions may, however, be more robustly extracted using global analysis to simultaneously fit the fluorescence decay data of all pixels in an image or dataset to a multi-exponential model under the assumption that the lifetime components are invariant across the image (dataset). This approach is often considered to be prohibitively slow and/or computationally expensive but we present here a computationally efficient global analysis algorithm for the analysis of time-correlated single photon counting (TCSPC) or time-gated FLIM data based on variable projection. It makes efficient use of both computer processor and memory resources, requiring less than a minute to analyse time series and multiwell plate datasets with hundreds of FLIM images on standard personal computers. This lifetime analysis takes account of repetitive excitation, including fluorescence photons excited by earlier pulses contributing to the fit, and is able to accommodate time-varying backgrounds and instrument response functions. We demonstrate that this global approach allows us to readily fit time-resolved fluorescence data to complex models including a four-exponential model of a FRET system, for which the FRET efficiencies of the two species of a bi-exponential donor are linked, and polarisation-resolved lifetime data, where a fluorescence intensity and bi-exponential anisotropy decay model is applied to the analysis of live cell homo-FRET data. A software package implementing this algorithm, FLIMfit, is available under an open source licence through the Open Microscopy Environment. PMID:23940626
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Han, Sung-Ho; Farshchi-Heydari, Salman; Hall, David J
2010-01-20
A novel time-domain optical method to reconstruct the relative concentration, lifetime, and depth of a fluorescent inclusion is described. We establish an analytical method for the estimations of these parameters for a localized fluorescent object directly from the simple evaluations of continuous wave intensity, exponential decay, and temporal position of the maximum of the fluorescence temporal point-spread function. Since the more complex full inversion process is not involved, this method permits a robust and fast processing in exploring the properties of a fluorescent inclusion. This method is confirmed by in vitro and in vivo experiments. Copyright 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.
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Wang, Li; Carnegie, Graeme K.
2013-01-01
Among methods to study protein-protein interaction inside cells, Bimolecular Fluorescence Complementation (BiFC) is relatively simple and sensitive. BiFC is based on the production of fluorescence using two non-fluorescent fragments of a fluorescent protein (Venus, a Yellow Fluorescent Protein variant, is used here). Non-fluorescent Venus fragments (VN and VC) are fused to two interacting proteins (in this case, AKAP-Lbc and PDE4D3), yielding fluorescence due to VN-AKAP-Lbc-VC-PDE4D3 interaction and the formation of a functional fluorescent protein inside cells. BiFC provides information on the subcellular localization of protein complexes and the strength of protein interactions based on fluorescence intensity. However, BiFC analysis using microscopy to quantify the strength of protein-protein interaction is time-consuming and somewhat subjective due to heterogeneity in protein expression and interaction. By coupling flow cytometric analysis with BiFC methodology, the fluorescent BiFC protein-protein interaction signal can be accurately measured for a large quantity of cells in a short time. Here, we demonstrate an application of this methodology to map regions in PDE4D3 that are required for the interaction with AKAP-Lbc. This high throughput methodology can be applied to screening factors that regulate protein-protein interaction. PMID:23979513
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Wang, Li; Carnegie, Graeme K
2013-08-15
Among methods to study protein-protein interaction inside cells, Bimolecular Fluorescence Complementation (BiFC) is relatively simple and sensitive. BiFC is based on the production of fluorescence using two non-fluorescent fragments of a fluorescent protein (Venus, a Yellow Fluorescent Protein variant, is used here). Non-fluorescent Venus fragments (VN and VC) are fused to two interacting proteins (in this case, AKAP-Lbc and PDE4D3), yielding fluorescence due to VN-AKAP-Lbc-VC-PDE4D3 interaction and the formation of a functional fluorescent protein inside cells. BiFC provides information on the subcellular localization of protein complexes and the strength of protein interactions based on fluorescence intensity. However, BiFC analysis using microscopy to quantify the strength of protein-protein interaction is time-consuming and somewhat subjective due to heterogeneity in protein expression and interaction. By coupling flow cytometric analysis with BiFC methodology, the fluorescent BiFC protein-protein interaction signal can be accurately measured for a large quantity of cells in a short time. Here, we demonstrate an application of this methodology to map regions in PDE4D3 that are required for the interaction with AKAP-Lbc. This high throughput methodology can be applied to screening factors that regulate protein-protein interaction.
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Multispectral fluorescence imaging techniques for nondestructive food safety inspection
NASA Astrophysics Data System (ADS)
Kim, Moon S.; Lefcourt, Alan M.; Chen, Yud-Ren
2004-03-01
The use of spectral sensing has gained acceptance as a rapid means for nondestructive inspection of postharvest food produce. Current technologies generally use color or a single wavelength camera technology. The applicability and sensitivity of these techniques can be expanded through the use of multiple wavelengths. Reflectance in the Vis/NIR is the prevalent spectral technique. Fluorescence, compared to reflectance, is regarded as a more sensitive technique due to its dynamic responses to subtle changes in biological entities. Our laboratory has been exploring fluorescence as a potential means for detection of quality and wholesomeness of food products. Applications of fluorescence sensing require an understanding of the spectral characteristics emanating from constituents and potential contaminants. A number of factors affecting fluorescence emission characteristics are discussed. Because of relatively low fluorescence quantum yield from biological samples, a system with a powerful pulse light source such as a laser coupled with a gated detection device is used to harvest fluorescence, in the presence of ambient light. Several fluorescence sensor platforms developed in our laboratory, including hyperspectral imaging, and laser-induced fluorescence (LIF) and steady-state fluorescence imaging systems with multispectral capabilities are presented. We demonstrate the potential uses of recently developed fluorescence imaging platforms in food safety inspection of apples contaminated with animal feces.
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Recent observations of the OI 8446 A emission over Millstone Hill
NASA Technical Reports Server (NTRS)
Lancaster, R. S.; Kerr, R. B.; Ng, K.; Noto, J.; Franco, M.; Solomon, Stanley C.
1994-01-01
Evening twilight spectra of the OI 8446 A emission were obtained during May and June of 1993 using a single-etalon, pressure scanning, Fabry-Perot interferometer located in the Millstone Hill Optical Facility. The goals of this work are to positively identify the 8446 A emission in the twilight airglow and to determine the intensity decay as a function of solar depression angle. Also, a study of the relative triplet line strengths is performed in hopes of establishing the importance of the primary excitation mechanisms (photoelectron impact or Bowen fluorescence) during the twilight period. Although absent in most of the data, a distinct auroral influence is also found to contribute considerably, on occasion, to the emission over Millstone Hill. The ratio of the combined 8446.26 A and 8446.38 A intensities to the 8446.76 A intensity varies as 0.13 +/- 0.03 per degree of solar depression angle, indicating that secondary excitation mechanisms are becoming increasingly important as evening twilight progresses. Bowen fluorescence is not found to be the primary excitation mechanism at any time during twilight, contributing just a few Rayleighs at most. These observations are an important first step toward a better characterization of highly variable thermospheric oxygen concentrations through ground-based measurements of the OI 8446 A emission.
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Li, Shi-Hua; Ge, Zhen-Ming; Xie, Li-Na; Chen, Wei; Yuan, Lin; Wang, Dong-Qi; Li, Xiu-Zhen; Zhang, Li-Quan
2018-02-05
The ecophysiological characteristics of native Phragmites australis and exotic Spartina alterniflora grown under waterlogging and salinity were investigated to explore their adaptation potential to sea level rise. The seasonal course of phenotypic traits, photosynthetic activity and chlorophyll fluorescence parameters of P. australis did not change remarkably under shallow flooding, whereas these variables were sensitive to increasing salinity. Waterlogging exacerbated the negative effects of salinity on shoot growth and photosynthetic activity of P. australis, and the combined stresses led to an absence of tassel and reproductive organs. By contrast, S. alterniflora performed well under both stresses and showed an obvious adaptation of salt secretion with increasing salinity. Light salinity was the optimal condition for S. alterniflora, and the tassel growth, chlorophyll content and fluorescence characters under moderate stresses did not differ notably. The Na + and Cl - concentrations in leaves of both species increased, and the K + content decreased in response to salinity. Under moderate and high saline levels, the ion concentrations in S. alterniflora were maintained at relatively consistent levels with increased salt secretion. We expect the degradation of P. australis and further colonization of S. alterniflora under prolonged flooding and saltwater intrusion from sea level rise on the coastline of China.
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Improving the monitoring of crop productivity using spaceborne solar-induced fluorescence.
Guan, Kaiyu; Berry, Joseph A; Zhang, Yongguang; Joiner, Joanna; Guanter, Luis; Badgley, Grayson; Lobell, David B
2016-02-01
Large-scale monitoring of crop growth and yield has important value for forecasting food production and prices and ensuring regional food security. A newly emerging satellite retrieval, solar-induced fluorescence (SIF) of chlorophyll, provides for the first time a direct measurement related to plant photosynthetic activity (i.e. electron transport rate). Here, we provide a framework to link SIF retrievals and crop yield, accounting for stoichiometry, photosynthetic pathways, and respiration losses. We apply this framework to estimate United States crop productivity for 2007-2012, where we use the spaceborne SIF retrievals from the Global Ozone Monitoring Experiment-2 satellite, benchmarked with county-level crop yield statistics, and compare it with various traditional crop monitoring approaches. We find that a SIF-based approach accounting for photosynthetic pathways (i.e. C3 and C4 crops) provides the best measure of crop productivity among these approaches, despite the fact that SIF sensors are not yet optimized for terrestrial applications. We further show that SIF provides the ability to infer the impacts of environmental stresses on autotrophic respiration and carbon-use-efficiency, with a substantial sensitivity of both to high temperatures. These results indicate new opportunities for improved mechanistic understanding of crop yield responses to climate variability and change. © 2015 John Wiley & Sons Ltd.
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Improving the Monitoring of Crop Productivity Using Spaceborne Solar-Induced Fluorescence
NASA Technical Reports Server (NTRS)
Guan, Kaiyu; Berry, Joseph A.; Zhang, Yongguang; Joiner, Joanna; Guanter, Luis; Badgley, Grayson; Lobell, David B.
2015-01-01
Large-scale monitoring of crop growth and yield has important value for forecasting food production and prices and ensuring regional food security. A newly emerging satellite retrieval, solar-induced fluorescence (SIF) of chlorophyll, provides for the first time a direct measurement related to plant photosynthetic activity (i.e. electron transport rate). Here, we provide a framework to link SIF retrievals and crop yield, accounting for stoichiometry, photosynthetic pathways, and respiration losses. We apply this framework to estimate United States crop productivity for 2007-2012, where we use the spaceborne SIF retrievals from the Global Ozone Monitoring Experiment-2 satellite, benchmarked with county-level crop yield statistics, and compare it with various traditional crop monitoring approaches. We find that a SIF-based approach accounting for photosynthetic pathways (i.e. C3 and C4 crops) provides the best measure of crop productivity among these approaches, despite the fact that SIF sensors are not yet optimized for terrestrial applications. We further show that SIF provides the ability to infer the impacts of environmental stresses on autotrophic respiration and carbon-use-efficiency, with a substantial sensitivity of both to high temperatures. These results indicate new opportunities for improved mechanistic understanding of crop yield responses to climate variability and change.
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Paula, Andreia S; Matos, João T V; Duarte, Regina M B O; Duarte, Armando C
2016-02-01
The chemical and light-absorption dynamics of organic aerosols (OAs), a master variable in the atmosphere, have yet to be resolved. This study uses a comprehensive multidimensional analysis approach for exploiting simultaneously the compositional changes over a molecular size continuum and associated light-absorption (ultraviolet absorbance and fluorescence) properties of two chemically distinct pools of urban OAs chromophores. Up to 45% of aerosol organic carbon (OC) is soluble in water and consists of a complex mixture of fluorescent and UV-absorbing constituents, with diverse relative abundances, hydrophobic, and molecular weight (Mw) characteristics between warm and cold periods. In contrast, the refractory alkaline-soluble OC pool (up to 18%) is represented along a similar Mw and light-absorption continuum throughout the different seasons. Results suggest that these alkaline-soluble chromophores may actually originate from primary OAs sources in the urban site. This work shows that the comprehensive multidimensional analysis method is a powerful and complementary tool for the characterization of OAs fractions. The great diversity in the chemical composition and optical properties of OAs chromophores, including both water-soluble and alkaline-soluble OC, may be an important contribution to explain the contrasting photo-reactivity and atmospheric behavior of OAs. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Lee, Patrick K H; Men, Yujie; Wang, Shanquan; He, Jianzhong; Alvarez-Cohen, Lisa
2015-02-03
Dehalococcoides mccartyi are functionally important bacteria that catalyze the reductive dechlorination of chlorinated ethenes. However, these anaerobic bacteria are fastidious to isolate, making downstream genomic characterization challenging. In order to facilitate genomic analysis, a fluorescence-activated cell sorting (FACS) method was developed in this study to separate D. mccartyi cells from a microbial community, and the DNA of the isolated cells was processed by whole genome amplification (WGA) and hybridized onto a D. mccartyi microarray for comparative genomics against four sequenced strains. First, FACS was successfully applied to a D. mccartyi isolate as positive control, and then microarray results verified that WGA from 10(6) cells or ∼1 ng of genomic DNA yielded high-quality coverage detecting nearly all genes across the genome. As expected, some inter- and intrasample variability in WGA was observed, but these biases were minimized by performing multiple parallel amplifications. Subsequent application of the FACS and WGA protocols to two enrichment cultures containing ∼10% and ∼1% D. mccartyi cells successfully enabled genomic analysis. As proof of concept, this study demonstrates that coupling FACS with WGA and microarrays is a promising tool to expedite genomic characterization of target strains in environmental communities where the relative concentrations are low.
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Treves, Haim; Raanan, Hagai; Finkel, Omri M; Berkowicz, Simon M; Keren, Nir; Shotland, Yoram; Kaplan, Aaron
2013-12-01
We recently isolated a small green alga from a biological sand crust (BSC) in the NW Negev, Israel. Based on its 18S rRNA and rbcL genes, it is a close relative of Chlorella sorokiniana and of certain strains of C. vulgaris and C. variabilis, but differs substantially in many aspects from C. sorokiniana. Because the classification of Chlorellales is still not resolved, we designated this species as C. ohadii (Trebouxiophyceae) in honor of Professor Itzhak Ohad. Under controlled laboratory conditions, C. ohadii showed marked structural and photosynthetic performance changes, depending on the carbon source used during growth, as well as remarkable resistance to photoinhibition. CO2 -dependent O2 evolution was not affected even when exposed to a light intensity of 3500 μmole photons m(-2) s(-1) , over 1.5 times the maximal intensity reached at the BSC surface, whereas the variable fluorescence declined sharply. We briefly discuss the use of fluorescence to assess photosynthetic rate and the implications of this finding for the assessment of global BSCs activity. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.
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S - and N-alkylating agents diminish the fluorescence of fluorescent dye-stained DNA.
Giesche, Robert; John, Harald; Kehe, Kai; Schmidt, Annette; Popp, Tanja; Balzuweit, Frank; Thiermann, Horst; Gudermann, Thomas; Steinritz, Dirk
2017-01-25
Sulfur mustard (SM), a chemical warfare agent, causes DNA alkylation, which is believed to be the main cause of its toxicity. SM DNA adducts are commonly used to verify exposure to this vesicant. However, the required analytical state-of-the-art mass-spectrometry methods are complex, use delicate instruments, are not mobile, and require laboratory infrastructure that is most likely not available in conflict zones. Attempts have thus been made to develop rapid detection methods that can be used in the field. The analysis of SM DNA adducts (HETE-G) by immunodetection is a convenient and suitable method. For a diagnostic assessment, HETE-G levels must be determined in relation to the total DNA in the sample. Total DNA can be easily visualized by the use of fluorescent DNA dyes. This study examines whether SM and related compounds affect total DNA staining, an issue that has not been investigated before. After pure DNA was extracted from human keratinocytes (HaCaT cells), DNA was exposed to different S- and N-alkylating agents. Our experiments revealed a significant, dose-dependent decrease in the fluorescence signal of fluorescent dye-stained DNA after exposure to alkylating agents. After mass spectrometry and additional fluorescence measurements ruled out covalent modifications of ethidium bromide (EthBr) by SM, we assumed that DNA crosslinks caused DNA condensation and thereby impaired access of the fluorescent dyes to the DNA. DNA digestion by restriction enzymes restored fluorescence, a fact that strengthened our hypothesis. However, monofunctional agents, which are unable to crosslink DNA, also decreased the fluorescence signal. In subsequent experiments, we demonstrated that protons produced during DNA alkylation caused a pH decrease that was found responsible for the reduction in fluorescence. The use of an appropriate buffer system eliminated the adverse effect of alkylating agents on DNA staining with fluorescent dyes. An appropriate buffer system is thus crucial for DNA quantification with fluorescent dyes in the presence of alkylating compounds. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
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Fluorescent protein vectors for pancreatic islet cell identification in live-cell imaging.
Shuai, Hongyan; Xu, Yunjian; Yu, Qian; Gylfe, Erik; Tengholm, Anders
2016-10-01
The islets of Langerhans contain different types of endocrine cells, which are crucial for glucose homeostasis. β- and α-cells that release insulin and glucagon, respectively, are most abundant, whereas somatostatin-producing δ-cells and particularly pancreatic polypeptide-releasing PP-cells are more scarce. Studies of islet cell function are hampered by difficulties to identify the different cell types, especially in live-cell imaging experiments when immunostaining is unsuitable. The aim of the present study was to create a set of vectors for fluorescent protein expression with cell-type-specific promoters and evaluate their applicability in functional islet imaging. We constructed six adenoviral vectors for expression of red and green fluorescent proteins controlled by the insulin, preproglucagon, somatostatin, or pancreatic polypeptide promoters. After transduction of mouse and human islets or dispersed islet cells, a majority of the fluorescent cells also immunostained for the appropriate hormone. Recordings of the sub-plasma membrane Ca(2+) and cAMP concentrations with a fluorescent indicator and a protein biosensor, respectively, showed that labeled cells respond to glucose and other modulators of secretion and revealed a striking variability in Ca(2+) signaling among α-cells. The measurements allowed comparison of the phase relationship of Ca(2+) oscillations between different types of cells within intact islets. We conclude that the fluorescent protein vectors allow easy identification of specific islet cell types and can be used in live-cell imaging together with organic dyes and genetically encoded biosensors. This approach will facilitate studies of normal islet physiology and help to clarify molecular defects and disturbed cell interactions in diabetic islets.
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NASA Astrophysics Data System (ADS)
Angulo-Rodríguez, Leticia M.; Laurence, Audrey; Jermyn, Michael; Sheehy, Guillaume; Sibai, Mira; Petrecca, Kevin; Roberts, David W.; Paulsen, Keith D.; Wilson, Brian C.; Leblond, Frédéric
2016-03-01
Cancer tissue often remains after brain tumor resection due to the inability to detect the full extent of cancer during surgery, particularly near tumor boundaries. Commercial systems are available for intra-operative real-time aminolevulenic acid (ALA)-induced protoporphyrin IX (PpIX) fluorescence imaging. These are standard white-light neurosurgical microscopes adapted with optical components for fluorescence excitation and detection. However, these instruments lack sensitivity and specificity, which limits the ability to detect low levels of PpIX and distinguish it from tissue auto-fluorescence. Current systems also cannot provide repeatable and un-biased quantitative fluorophore concentration values because of the unknown and highly variable light attenuation by tissue. We present a highly sensitive spectroscopic fluorescence imaging system that is seamlessly integrated onto a neurosurgical microscope. Hardware and software were developed to achieve through-microscope spatially-modulated illumination for 3D profilometry and to use this information to extract tissue optical properties to correct for the effects of tissue light attenuation. This gives pixel-by-pixel quantified fluorescence values and improves detection of low PpIX concentrations. This is achieved using a high-sensitivity Electron Multiplying Charge Coupled Device (EMCCD) with a Liquid Crystal Tunable Filter (LCTF) whereby spectral bands are acquired sequentially; and a snapshot camera system with simultaneous acquisition of all bands is used for profilometry and optical property recovery. Sensitivity and specificity to PpIX is demonstrated using brain tissue phantoms and intraoperative human data acquired in an on-going clinical study using PpIX fluorescence to guide glioma resection.
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Schaufele, Fred
2013-01-01
Förster resonance energy transfer (FRET) between fluorescent proteins (FPs) provides insights into the proximities and orientations of FPs as surrogates of the biochemical interactions and structures of the factors to which the FPs are genetically fused. As powerful as FRET methods are, technical issues have impeded their broad adoption in the biologic sciences. One hurdle to accurate and reproducible FRET microscopy measurement stems from variable fluorescence backgrounds both within a field and between different fields. Those variations introduce errors into the precise quantification of fluorescence levels on which the quantitative accuracy of FRET measurement is highly dependent. This measurement error is particularly problematic for screening campaigns since minimal well-to-well variation is necessary to faithfully identify wells with altered values. High content screening depends also upon maximizing the numbers of cells imaged, which is best achieved by low magnification high throughput microscopy. But, low magnification introduces flat-field correction issues that degrade the accuracy of background correction to cause poor reproducibility in FRET measurement. For live cell imaging, fluorescence of cell culture media in the fluorescence collection channels for the FPs commonly used for FRET analysis is a high source of background error. These signal-to-noise problems are compounded by the desire to express proteins at biologically meaningful levels that may only be marginally above the strong fluorescence background. Here, techniques are presented that correct for background fluctuations. Accurate calculation of FRET is realized even from images in which a non-flat background is 10-fold higher than the signal. PMID:23927839
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Chromophoric and fluorescent dissolved organic matter in and above the oxygen minimum zone off Peru
NASA Astrophysics Data System (ADS)
Loginova, A. N.; Thomsen, S.; Engel, A.
2016-11-01
As a result of nutrient upwelling, the Peruvian coastal system is one of the most productive regions in the ocean. Sluggish ventilation of intermediate waters, characteristic for the Eastern Tropical South Pacific (ETSP) and microbial degradation of a high organic matter load promotes deoxygenation at depth. Dissolved organic matter (DOM) plays a key role in microbial respiration and carbon cycling, but little is known on DOM distribution and cycling in the ETSP. DOM optical properties give important insights on DOM sources, structure and biogeochemical reactivity. Here, we present data and a conceptual view on distribution and cycling of chromophoric (CDOM) and fluorescent (FDOM) DOM in and above the oxygen minimum zone (OMZ) off Peru. Five fluorescent components were identified during PARAFAC analysis. Highest intensities of CDOM and of the amino acid-like fluorescent component (C3) occurred above the OMZ and coincided with maximum chl a concentrations, suggesting phytoplankton productivity as major source. High intensities of a marine humic-like fluorescent component (C1), observed in subsurface waters, indicated in situ microbial reworking of DOM. FDOM release from inner shelf sediment was determined by seawater analysis and continuous glider sensor measurement and included a humic-like component (C2) with a signature typical for terrestrially derived humic acids. Upwelling supplied humic-like substances to the euphotic zone. Photo-reactions were likely involved in the production of a humic-like fluorescent component (C5). Our data show that variable biological and physical processes need to be considered for understanding DOM cycling in a highly dynamic coastal upwelling system like the ETSP off Peru.
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NASA Astrophysics Data System (ADS)
Arantes Camargo, Livia; Marques Júnior, José; Reynaldo Ferracciú Alleoni, Luís; Tadeu Pereira, Gener; De Bortoli Teixeira, Daniel; Santos Rabelo de Souza Bahia, Angélica
2017-04-01
Environmental impact assessments may be assisted by spatial characterization of potentially toxic elements (PTEs). Diffuse reflectance spectroscopy (DRS) and X-ray fluorescence spectroscopy (XRF) are rapid, non-destructive, low-cost, prediction tools for a simultaneous characterization of different soil attributes. Although low concentrations of PTEs might preclude the observation of spectral features, their contents can be predicted using spectroscopy by exploring the existing relationship between the PTEs and soil attributes with spectral features. This study aimed to evaluate, in three geomorphic surfaces of Oxisols, the capacity for predicting PTEs (Ba, Co, and Ni) and their spatial variability by means of diffuse reflectance spectroscopy (DRS) and X-ray fluorescence spectroscopy (XRF). For that, soil samples were collected from three geomorphic surfaces and analyzed for chemical, physical, and mineralogical properties, and then analyzed in DRS (visible + near infrared - VIS+NIR and medium infrared - MIR) and XRF equipment. PTE prediction models were calibrated using partial least squares regression (PLSR). PTE spatial distribution maps were built using the values calculated by the calibrated models that reached the best accuracy using geostatistics. PTE prediction models were satisfactorily calibrated using MIR DRS for Ba, and Co (residual prediction deviation - RPD > 3.0), Vis DRS for Ni (RPD > 2.0) and FRX for all the studied PTEs (RPD > 1.8). DRS- and XRF-predicted values allowed the characterization and the understanding of spatial variability of the studied PTEs.
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Fluorescent probes for nucleic Acid visualization in fixed and live cells.
Boutorine, Alexandre S; Novopashina, Darya S; Krasheninina, Olga A; Nozeret, Karine; Venyaminova, Alya G
2013-12-11
This review analyses the literature concerning non-fluorescent and fluorescent probes for nucleic acid imaging in fixed and living cells from the point of view of their suitability for imaging intracellular native RNA and DNA. Attention is mainly paid to fluorescent probes for fluorescence microscopy imaging. Requirements for the target-binding part and the fluorophore making up the probe are formulated. In the case of native double-stranded DNA, structure-specific and sequence-specific probes are discussed. Among the latest, three classes of dsDNA-targeting molecules are described: (i) sequence-specific peptides and proteins; (ii) triplex-forming oligonucleotides and (iii) polyamide oligo(N-methylpyrrole/N-methylimidazole) minor groove binders. Polyamides seem to be the most promising targeting agents for fluorescent probe design, however, some technical problems remain to be solved, such as the relatively low sequence specificity and the high background fluorescence inside the cells. Several examples of fluorescent probe applications for DNA imaging in fixed and living cells are cited. In the case of intracellular RNA, only modified oligonucleotides can provide such sequence-specific imaging. Several approaches for designing fluorescent probes are considered: linear fluorescent probes based on modified oligonucleotide analogs, molecular beacons, binary fluorescent probes and template-directed reactions with fluorescence probe formation, FRET donor-acceptor pairs, pyrene excimers, aptamers and others. The suitability of all these methods for living cell applications is discussed.
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Wang, Zhiwei; Wu, Zhichao; Tang, Shujuan
2009-04-01
Three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy was employed to characterize dissolved organic matter (DOM) in a submerged membrane bioreactor (MBR). Three fluorescence peaks could be identified from the EEM fluorescence spectra of the DOM samples in the MBR. Two peaks were associated with the protein-like fluorophores, and the third was related to the visible humic acid-like fluorophores. Only two main peaks were observed in the EEM fluorescence spectra of the extracellular polymeric substance (EPS) samples, which were due to the fluorescence of protein-like and humic acid-like matters, respectively. However, the EEM fluorescence spectra of membrane foulants were observed to have three peaks. It was also found that the dominant fluorescence substances in membrane foulants were protein-like substances, which might be due to the retention of proteins in the DOM and/or EPS in the MBR by the fine pores of the membrane. Quantitative analysis of the fluorescence spectra including peak locations, fluorescence intensity, and different peak intensity ratios and the fluorescence regional integration (FRI) analysis were also carried out in order to better understand the similarities and differences among the EEM spectra of the DOM, EPS, and membrane foulant samples and to further provide an insight into membrane fouling caused by the fluorescence substances in the DOM in submerged MBRs.
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Intrafamilial and interfamilial variability of phenotype in familial velo-cardio-facial syndrome
DOE Office of Scientific and Technical Information (OSTI.GOV)
Hajianpour, M.J.; Lamb, A.; Covle, M.
Two half-sisters and their mother from one family, and two full-brothers and their mother from another family presented with features of velo-cardio-facial syndrome (VCSF)/DiGeorge syndrome (DS) with intrafamilial and interfamilial variability of phenotypic expression. None of these patients had an apparent cleft palate. Cardiac anomaly, jejunal atresia and hypocalcemia were present only in the newborn patient. Fluorescence in situ hybridization for VCFS/DS with probe D22S75 showed a deletion in the 22q11.2 region in patients available for the study.
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McGowan, K B; Kurtis, M S; Lottman, L M; Watson, D; Sah, R L
2002-07-01
To compare two fluorometric assays, utilizing (1) the bisbenzimidazole Hoechst 33258 and (2) PicoGreen, for determining DNA content in human cartilage. Human articular and nasal septal cartilage explants were digested using proteinase K. Portions of sample digest were analysed for intrinsic and dye-enhanced fluorescence with either Hoechst 33258 or PicoGreen. Intrinsic tissue fluorescence in both articular and septal cartilage increased with age and was prominent at wavelengths used for Hoechst 33258 but relatively low at wavelengths used for PicoGreen. The relative contribution of intrinsic fluorescence to total dye-enhanced fluorescence of human cartilage was markedly greater for Hoechst 33258 (19-57%) than for PicoGreen (2-7%). Thus, in many situations, DNA in human cartilage can be assayed using PicoGreen without the need to correct for intrinsic cartilage fluorescence. The enhancement of fluorescence by each dye was found to be specific for DNA, as shown by fluorescence spectra, >90% sensitivity to DNase, and resistance to RNase. In addition, little or no interference was caused by non-DNA tissue components, since DNA caused an equal enhancement in the absence or presence of proteinase K digested human cartilage, once intrinsic cartilage fluorescence was subtracted. PicoGreen was more sensitive for assaying DNA (0.9ng DNA/ml) than Hoechst 33258 (6ng DNA/ml) and can also be used in a microplate reader. PicoGreen can be used in a rapid and sensitive assay to quantify DNA in small samples of human cartilage. Copyright 2002 Published by Elsevier Science Ltd on behalf of OsteoArthritis Research Society International.
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Zhu, Dan; Zhao, Dongxia; Huang, Jiaxuan; Zhu, Yu; Chao, Jie; Su, Shao; Li, Jiang; Wang, Lihua; Shi, Jiye; Zuo, Xiaolei; Weng, Lixing; Li, Qian; Wang, Lianhui
2018-05-16
Identification of tumor-related mRNA in living cells hold great promise for early cancer diagnosis and pathological research. Herein, we present poly-adenine (polyA)-mediated fluorescent spherical nucleic acid (FSNA) probes for intracellular mRNA detection with regulable sensitivities by programmably adjusting the loading density of DNA on gold nano-interface. Gold nanoparticles (AuNPs) functionalized with polyA-tailed recognition sequences were hybridized to fluorescent "reporter" strands to fabricate fluorescence-quenched FSNA probes. While exposed to target gene, the "reporter" strands were released from FSNA through strand displacement and fluorescence was recovered. With polyA20 tail as the attaching block, the detection limit of FSNA probes was calculated to be 0.31 nM, which is ~55 fold lower than that of thiolated probes without surface density regulation. Quantitative intracellular mRNA detection and imaging could be achieved with polyA-mediated FSNA probes within 2 hours, indicating their application potential in rapid and sensitive intracellular target imaging. Copyright © 2018. Published by Elsevier Inc.
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Engineering an FMN-based iLOV protein for the detection of arsenic ions.
Ravikumar, Yuvaraj; Nadarajan, Saravanan Prabhu; Lee, Chong-Soon; Yun, Hyungdon
2017-05-15
Over the past few decades, genetically encoded fluorescent proteins have been widely used as efficient probes to explore and investigate the roles of metal ions in biological processes. The discovery of small FMN-based fluorescent proteins, such as iLOV and FbFP, has enabled researchers to exploit these fluorescent reporter proteins for metal-sensing applications. In this study, we report the inherent binding properties of iLOV towards arsenic ions. The fluorescence quenching of iLOV was linearly related to the concentration of arsenic ions, and engineered proteins showed better sensitivity than the wild-type protein. Engineering key residues around the chromophore converted the iLOV protein into a highly sensitive sensor for As 3+ ions. iLOV N468S exhibited an improved binding affinity with a dissociation constant of 1.5 μM. Furthermore, the circular dichroism spectra indicated that the fluorescence quenching mechanism might be related to arsenic-protein complex formation. Thus, the reagentless sensing of arsenic can potentially be exploited to determine intracellular or environmental arsenic using a genetically encoded biosensing approach. Copyright © 2017 Elsevier Inc. All rights reserved.
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Rant, Ulrich; Arinaga, Kenji; Fujita, Shozo; Yokoyama, Naoki; Abstreiter, Gerhard; Tornow, Marc
2004-11-09
We present optical investigations on the conformation of oligonucleotide layers on Au surfaces. Our studies concentrate on the effect of varying surface coverage densities on the structural properties of layers of 12- and 24mer single-stranded DNA, tethered to the Au surface at one end while being labeled with a fluorescent marker at the opposing end. The distance-dependent energy transfer from the marker dye to the metal surface, which causes quenching of the observed fluorescence, is used to provide information on the orientation of the DNA strands relative to the surface. Variations in the oligonucleotide coverage density, as determined from electrochemical quantification, over 2 orders of magnitude are achieved by employing different preparation conditions. The observed enhancement in fluorescence intensity with increasing DNA coverage can be related to a model involving mutual steric interactions of oligonucleotides on the surface, as well as fluorescence quenching theory. Finally, the applicability of the presented concepts for investigations of heterogeneous monolayers is demonstrated by means of studying the coadsorption of mercaptohexanol onto DNA-modified Au surfaces.
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Dewez, David; Didur, Olivier; Vincent-Héroux, Jonathan; Popovic, Radovan
2008-01-01
Photosynthetic-fluorescence parameters were investigated to be used as valid biomarkers of toxicity when alga Scenedesmus obliquus was exposed to isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea] effect. Chlorophyll fluorescence induction of algal cells treated with isoproturon showed inactivation of photosystem II (PSII) reaction centers and strong inhibition of PSII electron transport. A linear correlation was found (R2>or=0.861) between the change of cells density affected by isoproturon and the change of effective PSII quantum yield (PhiM'), photochemical quenching (qP) and relative photochemical quenching (qP(rel)) values. The cells density was also linearly dependent (R2=0.838) on the relative unquenched fluorescence parameter (UQF(rel)). Non-linear correlation was found (R2=0.937) only between cells density and the energy transfer efficiency from absorbed light to PSII reaction center (ABS/RC). The order of sensitivity determined by the EC-50% was: UQF(rel)>PhiM'>qP>qP(rel)>ABS/RC. Correlations between cells density and those photosynthetic-fluorescence parameters provide supporting evidence to use them as biomarkers of toxicity for environmental pollutants.
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NASA Technical Reports Server (NTRS)
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. We also show some significant differences between fluorescence and coincident normalized difference vegetation indices (NDVI) retrievals.
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NASA Technical Reports Server (NTRS)
Joiner, J.; Guanter, 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 0.5. We also show some significant differences between fluorescence and coincident normalized difference vegetation indices (NDVI) retrievals.
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USDA-ARS?s Scientific Manuscript database
Variable indirect photosynthetic rate (Pn) responses occur on injured leaves after insect herbivory. It is important to understand factors that influence indirect Pn reductions after injury. The current study examines the relationship between gas exchange and chlorophyll a fluorescence parameters wi...
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Relationships between phytoplankton dynamics and physiology, and environmental conditions were studied in Santa Rosa Sound, Florida, USA, at near-weekly intervals during 2001. Santa Rosa Sound is a component of the Pensacola Bay estuary in the northern Gulf of Mexico. Parameters ...
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USDA-ARS?s Scientific Manuscript database
Detection and rapid response to in-season changes of soil nutrient availability and plant needs with weather conditions and site-specific characteristics are essential to the optimal performance of an agronomic crop production system. With recent advances in material science, detector design and se...
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Chemical Variations in a Granitic Pluton and Its Surrounding Rocks.
Baird, A K; McIntyre, D B; Welday, E E; Madlem, K W
1964-10-09
New techniques of x-ray fluorescence spectrography have provided, for the first time, abundant data regarding chemical variability of granitic rocks on different scales. The results suggest that current designs of sampling plans for trend surface analysis should be modified; in particular several specimens, preferably drillcores, may be required at each locality.
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Processes Affecting the Variability of Fluorescence Signals from Benthic Targets in Shallow Waters
2001-09-30
symbiotic corals. - Limnol. and Oceanogr., 46: 75-85. Gorbunov M.Y. and Falkowski P.G. 2001. Photoreceptors in the cnidarian hosts allow symbiotic...Gorbunov M.Y. and Falkowski P.G. 2001. Photoreceptors in the cnidarian hosts allow symbiotic corals to sense blue moonlight. – Limnol. and Oceanogr
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Optimizing ultrafast illumination for multiphoton-excited fluorescence imaging
Stoltzfus, Caleb R.; Rebane, Aleksander
2016-01-01
We study the optimal conditions for high throughput two-photon excited fluorescence (2PEF) and three-photon excited fluorescence (3PEF) imaging using femtosecond lasers. We derive relations that allow maximization of the rate of imaging depending on the average power, pulse repetition rate, and noise characteristics of the laser, as well as on the size and structure of the sample. We perform our analysis using ~100 MHz, ~1 MHz and 1 kHz pulse rates and using both a tightly-focused illumination beam with diffraction-limited image resolution, as well loosely focused illumination with a relatively low image resolution, where the latter utilizes separate illumination and fluorescence detection beam paths. Our theoretical estimates agree with the experiments, which makes our approach especially useful for optimizing high throughput imaging of large samples with a field-of-view up to 10x10 cm2. PMID:27231620
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NASA Technical Reports Server (NTRS)
Dobson, Chris C.
1999-01-01
Sodium fluorescence induced by a narrow-bandwidth tunable laser has been used to measure temperature, pressure, axial velocity, and species concentrations in wind tunnels, rocket engine exhausts, and the upper atmosphere. Optical pumping of the ground states of the sodium, however, can radically alter the shape of the laser-induced fluorescence excitation spectrum, complicating such measurements. Here a straightforward extension of rate equations originally proposed to account for the features of the pumped spectrum is used to make temperature measurements from spectra taken in pumped vapor. Also determined from the spectrum is the relative fluorescence cycle number, which has application to measurement of diffusion rate and transverse flow velocity, The accuracy of both the temperature and the cycle-number measurements is comparable with that of temperature measurements made in the absence of pumping.
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Pereira da Silva Neves, Marta Maria; González-García, María Begoña; Pérez-Junquera, Alejandro; Hernández-Santos, David; Fanjul-Bolado, Pablo
2018-05-01
In this work, a turn-off photoluminescent sensing proof-of-concept based on blue luminescent graphene quantum dots (GQDs) as the fluorescent probe was developed. For that purpose, GQDs optical response was related with the catalytic enzymatic activity of alkaline phosphatase (ALP), in the presence of hydroquinone diphosphate (HQDP). The hydrolysis of HQDP by ALP generated hydroquinone (HQ). The oxidation of HQ, enzymatically produced, to p-benzoquinone (BQ) resulted in the quenching of GQDs fluorescence (FL). Therefore, the developed luminescent sensing mechanism allowed the FL quenching with ALP activity to be related and thus quantified the concentration of ALP down to 0.5 nM of enzyme. This innovative design principle appears as a promising tool for the development of enzymatic sensors based on ALP labeling with fluorescent detection or even for direct ALP luminescent quantification in an easy, fast and sensitive manner. Copyright © 2018 John Wiley & Sons, Ltd.
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Reduced Fluoresceinamine as a Fluorescent Sensor for Nitric Oxide
Duarte, Abel J.; Esteves da Silva, Joaquim C.G.
2010-01-01
A new fluorescent sensor for nitric oxide (NO) is presented that is based on its reaction with a non fluorescent substance, reduced fluoresceinamine, producing the highly fluorescent fluoresceinamine. Using a portable homemade stabilized light source consisting of 450 nm LED and fiber optics to guide the light, the sensor responds linearly within seconds in the NO concentration range between about 10–750 μM with a limit of detection (LOD) of about 1 μM. The system generated precise intensity readings, with a relative standard deviation of less than 1%. The suitability of the sensor was assessed by monitoring the NO generated by either the nitrous acid decomposition reaction or from a NO-releasing compound. Using relatively high incubation times, the sensor also responds quantitatively to hydrogen peroxide and potassium superoxide, however, using transient signal measurements results in no interfering species. PMID:22294892
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Maye, Peter; Stover, Mary Louise; Liu, Yaling; Rowe, David W; Gong, Shiaochin; Lichtler, Alexander C
2009-03-13
Reporter gene mice are valuable animal models for biological research providing a gene expression readout that can contribute to cellular characterization within the context of a developmental process. With the advancement of bacterial recombination techniques to engineer reporter gene constructs from BAC genomic clones and the generation of optically distinguishable fluorescent protein reporter genes, there is an unprecedented capability to engineer more informative transgenic reporter mouse models relative to what has been traditionally available. We demonstrate here our first effort on the development of a three stage bacterial recombination strategy to physically link multiple genes together with their respective fluorescent protein (FP) reporters in one DNA fragment. This strategy uses bacterial recombination techniques to: (1) subclone genes of interest into BAC linking vectors, (2) insert desired reporter genes into respective genes and (3) link different gene-reporters together. As proof of concept, we have generated a single DNA fragment containing the genes Trap, Dmp1, and Ibsp driving the expression of ECFP, mCherry, and Topaz FP reporter genes, respectively. Using this DNA construct, we have successfully generated transgenic reporter mice that retain two to three gene readouts. The three stage methodology to link multiple genes with their respective fluorescent protein reporter works with reasonable efficiency. Moreover, gene linkage allows for their common chromosomal integration into a single locus. However, the testing of this multi-reporter DNA construct by transgenesis does suggest that the linkage of two different genes together, despite their large size, can still create a positional effect. We believe that gene choice, genomic DNA fragment size and the presence of endogenous insulator elements are critical variables.
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Mandal, Deep; Kar, Tanmoy; Das, Prasanta Kumar
2014-01-27
With the rapid progress in the development of supramolecular soft materials, examples of low-molecular-weight gelators (LMWGs) with the ability to immobilise both water and organic solvents by the same structural scaffold are very limited. In this paper, we report the development of pyrene-containing peptide-based ambidextrous gelators (AGs) with the ability to efficiently gelate both organic and aqueous solvents. The organo- and hydrogelation efficiencies of these gelators are in the range 0.7-1.1% w/v in various organic solvents and 0.5-5% w/v in water at certain acidic pH values (pH 2.0-4.0). Moreover, for the first time, AGs have been utilised to prepare single-walled carbon-nanotube (SWNT)-included soft nanocomposites in both hydro- and organogel matrices. The influence of different non-covalent interactions such as hydrogen bonding, hydrophobic, π-π and van der Waals interactions in self-assembled gelation has been studied in detail by circular dichroism, FTIR, variable-temperature NMR, 2D NOESY and luminescence spectroscopy. Interestingly, the presence of the pyrene moiety in the structure rendered these AGs intrinsically fluorescent, which was quenched upon successful integration of the SWNTs within the gel. The prepared hydro- and organogels along with their SWNT-integrated nanocomposites are thermoreversible in nature. The supramolecular morphologies of the dried gels and SWNT-gel nanocomposites have been studied by transmission electron microscopy, fluorescence microscopy and polarising optical microscopy, which confirmed the presence of three-dimensional self-assembled fibrillar networks (SAFINs) as well as the integrated SWNTs. Importantly, rheological studies revealed that the inclusion of SWNTs within the ambidextrous gels improved the mechanical rigidity of the resulting soft nanocomposites up to 3.8-fold relative to the native gels. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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A rapid, automated approach for quantitation of rotavirus and reovirus infectivity.
Iskarpatyoti, Jason A; Willis, Janet Z; Guan, John; Morse, E Ashley; Ikizler, Miné; Wetzel, J Denise; Dermody, Terence S; Contractor, Nikhat
2012-09-01
Current microscopy-based approaches for immunofluorescence detection of viral infectivity are time consuming and labor intensive and can yield variable results subject to observer bias. To circumvent these problems, we developed a rapid and automated infrared immunofluorescence imager-based infectivity assay for both rotavirus and reovirus that can be used to quantify viral infectivity and infectivity inhibition. For rotavirus, monolayers of MA104 cells were infected with simian strain SA-11 or SA-11 preincubated with rotavirus-specific human IgA. For reovirus, monolayers of either HeLa S3 cells or L929 cells were infected with strains type 1 Lang (T1L), type 3 Dearing (T3D), or either virus preincubated with a serotype-specific neutralizing monoclonal antibody (mAb). Infected cells were fixed and incubated with virus-specific polyclonal antiserum, followed by an infrared fluorescence-conjugated secondary antibody. Well-to-well variation in cell number was normalized using fluorescent reagents that stain fixed cells. Virus-infected cells were detected by scanning plates using an infrared imager, and results were obtained as a percent response of fluorescence intensity relative to a virus-specific standard. An expected dose-dependent inhibition of both SA-11 infectivity with rotavirus-specific human IgA and reovirus infectivity with T1L-specific mAb 5C6 and T3D-specific mAb 9BG5 was observed, confirming the utility of this assay for quantification of viral infectivity and infectivity blockade. The imager-based viral infectivity assay fully automates data collection and provides an important advance in technology for applications such as screening for novel modulators of viral infectivity. This basic platform can be adapted for use with multiple viruses and cell types. Copyright © 2012 Elsevier B.V. All rights reserved.
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2010-11-15
fluorescence emission of vegetation for mapping vegetation stress as chlorophyll content and/or carotenoid content changes. 1. REPORT DATE (DD-MM-YYYY...that estimate fluorescence emission of vegetation for mapping vegetation stress as chlorophyll content and/or carotenoid content changes...not related to changes in chlorophyll content or the carotenoids /chlorophyll ratio. PRI is an indicator of chronic salinity stress and may be used as
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Fluorescence decay kinetics and imaging of NAD(P)H and flavins as metabolic indicators
NASA Astrophysics Data System (ADS)
Schneckenburger, Herbert; Koenig, Karsten
1992-07-01
The intrinsic fluorescence of various cell cultures in the blue and green spectral range has been attributed mainly to hydrated nicotinamide adenine dinucleotide (NADH) and flavin molecules. Their fluorescence decay curves were measured with subnanosecond resolution. The reduced coenzymes NADH and hydrated nicotinamide adenine dinucleotide phosphate NADPH, both showed a biexponential decay pattern in solution with similar time constants, but different relative intensities of the two components. They could thus be distinguished from one another as well as from their oxidized forms. The NADPH fluorescence of Saccharomyces cerevisiae was located within the cytoplasm and its organelles and was by about a factor of 4 higher for respiratory-deficient than for intact yeast strains. Intracellular flavin fluorescence showed a triexponential behavior--probably due to a superposition of protein-bound and free flavin molecules. The lifetime of the shortest component varied within the range of 0.20 to 0.50 ns between respiratory-deficient and intact yeast strains, and the relative intensity of this component was most pronounced for the intact strain DL1. Time- resolved fluorescence seems therefore to be an appropriate method of probe the function of the respiratory chain and--in the further step--to differentiate between various types of cells and tissues in medical diagnosis or environmental research.
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Choi, Y.; Eng, P.; Stubbs, J.; ...
2016-08-21
In this paper, X-ray standing wave fluorescence yield depth profiling was used to determine the solar wind implanted Fe and Ni fluences in a silicon-on-sapphire (SoS) Genesis collector (60326). An internal reference standardization method was developed based on fluorescence from Si and Al in the collector materials. Measured Fe fluence agreed well with that measured previously by us on a sapphire collector (50722) as well as SIMS results by Jurewicz et al. Measured Ni fluence was higher than expected by a factor of two; neither instrumental errors nor solar wind fractionation effects are considered significant perturbations to this value. Impuritymore » Ni within the epitaxial Si layer, if present, could explain the high Ni fluences and therefore needs further investigation. As they stand, these results are consistent with minor temporally-variable Fe and Ni fractionation on the timescale of a year.« less
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Macinnis-Ng, Catriona M O; Ralph, Peter J
2002-01-01
This in situ study used photosynthetic activity (measured as chlorophyll a fluorescence) and photosynthetic pigment concentrations to assess the effect of copper, cadmium, lead and zinc on the seagrass Zostera capricorni. Custom-made portable in situ exposure (PIE) chambers were developed so seagrasses could be dosed within the meadow. Z capricorni was exposed to 0.1 and I mg l(-1) of metal solutions for 10 h. During this time and for the subsequent four-day recovery period, the effective quantum yield of photosystem II (PS II) (deltaF/Fm') was measured. While the results were variable, copper and zinc exposed samples had a depressed deltaF/Fm' during the exposure period. Samples exposed to zinc recovered to pre-exposure levels but those exposed to copper did not. Cadmium and lead did not impact on the chlorophyll a fluorescence and the chlorophyll pigment data supported these findings. This study presents an innovative new application of chlorophyll a fluorescence stress assessment.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Choi, Y.; Eng, P.; Stubbs, J.
In this paper, X-ray standing wave fluorescence yield depth profiling was used to determine the solar wind implanted Fe and Ni fluences in a silicon-on-sapphire (SoS) Genesis collector (60326). An internal reference standardization method was developed based on fluorescence from Si and Al in the collector materials. Measured Fe fluence agreed well with that measured previously by us on a sapphire collector (50722) as well as SIMS results by Jurewicz et al. Measured Ni fluence was higher than expected by a factor of two; neither instrumental errors nor solar wind fractionation effects are considered significant perturbations to this value. Impuritymore » Ni within the epitaxial Si layer, if present, could explain the high Ni fluences and therefore needs further investigation. As they stand, these results are consistent with minor temporally-variable Fe and Ni fractionation on the timescale of a year.« less
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Sitepu, I.R.; Ignatia, L.; Franz, A. K.; Wong, D. M.; Faulina, S.A.; Tsui, M.; Kanti, A.; Boundy-Mills, K.
2012-01-01
A rapid and inexpensive method for estimating lipid content of yeasts is needed for screening large numbers of yeasts samples. Nile red is a fluorescent lipophilic dye used for detection and quantification of intracellular lipid droplets in various biological system including algae, yeasts and filamentous fungi. However, a published assay for yeast is affected by variable diffusion across the cell membrane, and variation in the time required to reach maximal fluorescence emission. In this study, parameters that may influence the emission were varied to determine optimal assay conditions. An improved assay with a high-throughput capability was developed that includes the addition of dimethyl sulfoxide (DMSO) solvent to improve cell permeability, elimination of the washing step, the reduction of Nile red concentration, kinetic readings rather than single time-point reading, and utilization of a black 96-well microplate. The improved method was validated by comparison to gravimetric determination of lipid content of a broad variety of ascomycete and basidiomycete yeast species. PMID:22985718
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Paintdakhi, Ahmad; Parry, Bradley; Campos, Manuel; Irnov, Irnov; Elf, Johan; Surovtsev, Ivan; Jacobs-Wagner, Christine
2016-01-01
Summary With the realization that bacteria display phenotypic variability among cells and exhibit complex subcellular organization critical for cellular function and behavior, microscopy has re-emerged as a primary tool in bacterial research during the last decade. However, the bottleneck in today’s single-cell studies is quantitative image analysis of cells and fluorescent signals. Here, we address current limitations through the development of Oufti, a stand-alone, open-source software package for automated measurements of microbial cells and fluorescence signals from microscopy images. Oufti provides computational solutions for tracking touching cells in confluent samples, handles various cell morphologies, offers algorithms for quantitative analysis of both diffraction and non-diffraction-limited fluorescence signals, and is scalable for high-throughput analysis of massive datasets, all with subpixel precision. All functionalities are integrated in a single package. The graphical user interface, which includes interactive modules for segmentation, image analysis, and post-processing analysis, makes the software broadly accessible to users irrespective of their computational skills. PMID:26538279
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Direct imaging of APP proteolysis in living cells.
Parenti, Niccoló; Del Grosso, Ambra; Antoni, Claudia; Cecchini, Marco; Corradetti, Renato; Pavone, Francesco S; Calamai, Martino
2017-01-01
Alzheimer's disease is a multifactorial disorder caused by the interaction of genetic, epigenetic and environmental factors. The formation of cytotoxic oligomers consisting of A β peptide is widely accepted as being one of the main key events triggering the development of Alzheimer's disease. A β peptide production results from the specific proteolytic processing of the amyloid precursor protein (APP). Deciphering the factors governing the activity of the secretases responsible for the cleavage of APP is still a critical issue. Kits available commercially measure the enzymatic activity of the secretases from cells lysates, in vitro . By contrast, we have developed a prototypal rapid bioassay that provides visible information on the proteolytic processing of APP directly in living cells. APP was fused to a monomeric variant of the green fluorescent protein and a monomeric variant of the red fluorescent protein at the C-terminal and N-terminal (mChAPPmGFP), respectively. Changes in the proteolytic processing rate in transfected human neuroblastoma and rat neuronal cells were imaged with confocal microscopy as changes in the red/green fluorescence intensity ratio. The significant decrease in the mean red/green ratio observed in cells over-expressing the β -secretase BACE1, or the α -secretase ADAM10, fused to a monomeric blue fluorescent protein confirms that the proteolytic site is still accessible. Specific siRNA was used to evaluate the contribution of endogenous BACE1. Interestingly, we found that the degree of proteolytic processing of APP is not completely homogeneous within the same single cell, and that there is a high degree of variability between cells of the same type. We were also able to follow with a fluorescence spectrometer the changes in the red emission intensity of the extracellular medium when BACE1 was overexpressed. This represents a complementary approach to fluorescence microscopy for rapidly detecting changes in the proteolytic processing of APP in real time. In order to allow the discrimination between the α - and the β -secretase activity, we have created a variant of mChAPPmGFP with a mutation that inhibits the α -secretase cleavage without perturbing the β -secretase processing. Moreover, we obtained a quantitatively robust estimate of the changes in the red/green ratio for the above conditions by using a flow cytometer able to simultaneously excite and measure the red and green fluorescence. Our novel approach lay the foundation for a bioassay suitable to study the effect of drugs or particular conditions, to investigate in an unbiased way the the proteolytic processing of APP in single living cells in order, and to elucidate the causes of the variability and the factors driving the processing of APP.
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Hydrothermal deposition on the Juan de Fuca Ridge over multiple glacial-interglacial cycles
NASA Astrophysics Data System (ADS)
Costa, Kassandra M.; McManus, Jerry F.; Middleton, Jennifer L.; Langmuir, Charles H.; Huybers, Peter J.; Winckler, Gisela; Mukhopadhyay, Sujoy
2017-12-01
Hydrothermal systems play an important role in modern marine chemistry, but little is known about how they may have varied on 100,000 year timescales. Here we present high-resolution records of non-lithogenic metal fluxes within sediment cores covering the last 500,000 years of hydrothermal deposition on the flanks of the Juan de Fuca Ridge. Six adjacent, gridded cores were analyzed by x-ray fluorescence for Fe, Mn, and Cu concentrations, corrected for lithogenic inputs with Ti, and normalized to excess initial 230Th to generate non-lithogenic metal flux records that provide the longest orbitally resolved reconstructions of hydrothermal activity currently available. Fe fluxes vary with global sea level over the last two glacial cycles, suggesting higher hydrothermal deposition during interglacial periods. The observed negative relationship between Fe and Mn indicates variable sediment redox conditions and diagenetic remobilization of sedimentary Mn over time. Thus, Mn fluxes may not be a reliable indicator for hydrothermal activity in the Juan de Fuca Ridge sediment cores. Cu fluxes show substantial high-frequency variability that may be linked to changes in vent temperature related to increased magmatic production during glacial periods. Deglacial hydrothermal peaks on the Juan de Fuca Ridge are consistent with previously published records from the Mid-Atlantic Ridge and the East Pacific Rise. Moreover, on the Juan de Fuca Ridge, the deglacial peaks in hydrothermal activity are followed by relatively high hydrothermal fluxes throughout the ensuing interglacial periods relative to the previous glacial period.
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Ďurkovič, Jaroslav; Čaňová, Ingrid; Lagaňa, Rastislav; Kučerová, Veronika; Moravčík, Michal; Priwitzer, Tibor; Urban, Josef; Dvořák, Miloň; Krajňáková, Jana
2013-01-01
Background and Aims Previous studies have shown that Ophiostoma novo-ulmi, the causative agent of Dutch elm disease (DED), is able to colonize remote areas in infected plants of Ulmus such as the leaf midrib and secondary veins. The objective of this study was to compare the performances in leaf traits between two Dutch elm hybrids ‘Groeneveld’ and ‘Dodoens’ which possess a contrasting tolerance to DED. Trait linkages were also tested with leaf mass per area (LMA) and with the reduced Young's modulus of elasticity (MOE) as a result of structural, developmental or functional linkages. Methods Measurements and comparisons were made of leaf growth traits, primary xylem density components, gas exchange variables and chlorophyll a fluorescence yields between mature plants of ‘Groeneveld’ and ‘Dodoens’ grown under field conditions. A recently developed atomic force microscopy technique, PeakForce quantitative nanomechanical mapping, was used to reveal nanomechanical properties of the cell walls of tracheary elements such as MOE, adhesion and dissipation. Key Results ‘Dodoens’ had significantly higher values for LMA, leaf tissue thickness variables, tracheary element lumen area (A), relative hydraulic conductivity (RC), gas exchange variables and chlorophyll a fluorescence yields. ‘Groeneveld’ had stiffer cell walls of tracheary elements, and higher values for water-use efficiency and leaf water potential. Leaves with a large carbon and nutrient investment in LMA tended to have a greater leaf thickness and a higher net photosynthetic rate, but LMA was independent of RC. Significant linkages were also found between the MOE and some vascular traits such as RC, A and the number of tracheary elements per unit area. Conclusions Strong dissimilarities in leaf trait performances were observed between the examined Dutch elm hybrids. Both hybrids were clearly separated from each other in the multivariate leaf trait space. Leaf growth, vascular and gas exchange traits in the infected plants of ‘Dodoens’ were unaffected by the DED fungus. ‘Dodoens’ proved to be a valuable elm germplasm for further breeding strategies. PMID:23264236
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Short communication: Labeling Listeria with anaerobic fluorescent protein for food safety studies.
Landete, José M; Peirotén, Ángela; Medina, Margarita; Arqués, Juan L
2017-01-01
Many food safety-related studies require the tracking of inoculated food-borne pathogens to monitor their fate in food complex environments. In the current study, we demonstrate the potential of plasmids containing the fluorescence protein gene evoglow-Pp1 (Evocatal, Dusseldorf, Germany) as a real-time reporter system for Listeria strains. This anaerobic fluorescent protein provides an easily detectable phenotype of microorganisms for food safety studies. This work is the first to report a reliable method to identify fluorescently labeled Listeria strains in food ecosystems. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
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Fluorescent screens and image processing for the APS linac test stand
DOE Office of Scientific and Technical Information (OSTI.GOV)
Berg, W.; Ko, K.
A fluorescent screen was used to monitor relative beam position and spot size of a 56-MeV electron beam in the linac test stand. A chromium doped alumina ceramic screen inserted into the beam was monitored by a video camera. The resulting image was captured using a frame grabber and stored into memory. Reconstruction and analysis of the stored image was performed using PV-WAVE. This paper will discuss the hardware and software implementation of the fluorescent screen and imaging system. Proposed improvements for the APS linac fluorescent screens and image processing will also be discussed.
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Measurement of the fluorescence of crop residues: A tool for controlling soil erosion
NASA Technical Reports Server (NTRS)
Daughtry, C. S. T.; Mcmurtrey, J. E., III; Chappelle, E. W.; Hunter, W. J.
1994-01-01
Management of crop residues, the portion of a crop left in the field after harvest, is an important conservation practice for minimizing soil erosion and for improving water quality. Quantification of crop residue cover is required to evaluate the effectiveness of conservation tillage practices. Methods are needed to quantify residue cover that are rapid, accurate, and objective. The fluorescence of crop residue was found to be a broadband phenomenon with emission maxima at 420 to 495 nm for excitations of 350 to 420 nm. Soils had low intensity broadband emissions over the 400 to 690 nm region for excitations of 300 to 600 nm. The range of relative fluorescence intensities for the crop residues was much greater than the fluorescence observed of the soils. As the crop residues decompose their blue fluorescence values approach the fluorescence of the soil. Fluorescence techniques are concluded to be less ambiguous and better suited for discriminating crop residues and soils than reflectance methods. If properly implemented, fluorescence techniques can be used to quantify, not only crop residue cover, but also photosynthetic efficiency in the field.
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NADPH as a potential intrinsic probe for tumour margin estimation
NASA Astrophysics Data System (ADS)
Stewart, Hazel; Hupp, Ted R.; Birch, David J. S.
2018-03-01
The fluorescent properties of the reduced coenzyme NADH and its phosphorylated derivative (NADPH) have been explored in order to assess their potential as an intrinsic probe for cancer surgery. NADPH production is increased in cancer cells to quench reactive oxygen species and meet higher demands for biosynthesis, and has attractive fluorescent properties such as emission towards the visible part of the spectrum and a relatively long fluorescence lifetime upon binding to enzymes ( 1 - 6.5 ns) that helps discriminate against other endogenous species. Different environmental effects on NAD(P)H fluorescence are reported here, including an increase in lifetime upon oxygen removal, an ability to retain its fluorescent properties in a complex medium (a silica phantom) and its fluorescence lifetime also being distinguishable in a cell environment. In addition, the development of a miniaturized liquid light guide filter-based timecorrelated single photon counting fluorescence lifetime system is reported as a step towards time-resolved visual imaging in cancer surgery. This system has been demonstrated as being capable of accurately measuring NAD(P)H fluorescence lifetimes in both simple solvent and cellular environments.
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NASA Astrophysics Data System (ADS)
Maeno, Akihiro; Kato, Yuko; Jimbo, Mitsuru; Amada, Kei; Mita, Hajime; Akasaka, Kazuyuki
2017-04-01
We have investigated conformational fluctuations in a new green fluorescent protein(GFP)-like protein rb-Akane found in a red-brown-colored octocoral, Scleronephthya gracillima (Kuekenthal)), with high pressure fluorescence spectroscopy at 0.1-700 MPa. Besides the green fluorescence at 510 nm, two red fluorescence peaks are observed at 590 and 629 nm, the relative intensity of which varies reversibly with pressure. The phenomenon is interpreted as representing the cis-trans isomerization of the chromophore accompanied by the conformational transition between two sub-states of the red fluorescence form of rb-Akane. The two sub-states are separated only marginally in free energy (ΔG0 = 1.9 ± 0.4 kJ mol-1), but significantly in partial molar volume (ΔV0 = -19.8 ± 1.4 ml mol-1) at 0.1 MPa (pH 7.5, 25°C). Above 500 MPa, the fluorescence at λmax 629 nm undergoes another reversible change with pressure, showing the onset of unfolding.
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NASA Astrophysics Data System (ADS)
Lee, T.; Bessler, W. G.; Yoo, J.; Schulz, C.; Jeffries, J. B.; Hanson, R. K.
2008-11-01
The fluorescence quantum yield for ultraviolet laser-induced fluorescence of CO2 is determined for selected excitation wavelengths in the range 215-250 nm. Wavelength-resolved laser-induced fluorescence (LIF) spectra of CO2, NO, and O2 are measured in the burned gases of a laminar CH4/air flame ( φ=0.9 and 1.1) at 20 bar with additional NO seeded into the flow. The fluorescence spectra are fit to determine the relative contribution of the three species to infer an estimate of fluorescence quantum yield for CO2 that ranges from 2-8×10-6 depending on temperature and excitation wavelength with an estimated uncertainty of ±0.5×10-6. The CO2 fluorescence signal increases linearly with gas pressure for flames with constant CO2 mole fraction for the 10 to 60 bar range, indicating that collisional quenching is not an important contributor to the CO2 fluorescence quantum yield. Spectral simulation calculations are used to choose two wavelengths for excitation of CO2, 239.34 and 242.14 nm, which minimize interference from LIF of NO and O2. Quantitative LIF images of CO2 are demonstrated using these two excitation wavelengths and the measured fluorescence quantum yield.
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Yan, Yuling; Marriott, M Emma; Petchprayoon, Chutima; Marriott, Gerard
2011-02-01
Few to single molecule imaging of fluorescent probe molecules can provide information on the distribution, dynamics, interactions and activity of specific fluorescently tagged proteins during cellular processes. Unfortunately, these imaging studies are made challenging in living cells because of fluorescence signals from endogenous cofactors. Moreover, related background signals within multi-cell systems and intact tissue are even higher and reduce signal contrast even for ensemble populations of probe molecules. High-contrast optical imaging within high-background environments will therefore require new ideas on the design of fluorescence probes, and the way their fluorescence signals are generated and analysed to form an image. To this end, in the present review we describe recent studies on a new family of fluorescent probe called optical switches, with descriptions of the mechanisms that underlie their ability to undergo rapid and reversible transitions between two distinct states. Optical manipulation of the fluorescent and non-fluorescent states of an optical switch probe generates a modulated fluorescence signal that can be isolated from a larger unmodulated background by using OLID (optical lock-in detection) techniques. The present review concludes with a discussion on select applications of synthetic and genetically encoded optical switch probes and OLID microscopy for high-contrast imaging of specific proteins and membrane structures within living systems.
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Fluorescence Modulation of Green Fluorescent Protein Using Fluorinated Unnatural Amino Acids.
Villa, Jordan K; Tran, Hong-Anh; Vipani, Megha; Gianturco, Stephanie; Bhasin, Konark; Russell, Brent L; Harbron, Elizabeth J; Young, Douglas D
2017-07-16
The ability to modulate protein function through minimal perturbations to amino acid structure represents an ideal mechanism to engineer optimized proteins. Due to the novel spectroscopic properties of green fluorescent protein, it has found widespread application as a reporter protein throughout the fields of biology and chemistry. Using site-specific amino acid mutagenesis, we have incorporated various fluorotyrosine residues directly into the fluorophore of the protein, altering the fluorescence and shifting the pKa of the phenolic proton associated with the fluorophore. Relative to wild type GFP, the fluorescence spectrum of the protein is altered with each additional fluorine atom, and the mutant GFPs have the potential to be employed as pH sensors due to the altered electronic properties of the fluorine atoms.
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Multispectral laser-induced fluorescence imaging system for large biological samples
NASA Astrophysics Data System (ADS)
Kim, Moon S.; Lefcourt, Alan M.; Chen, Yud-Ren
2003-07-01
A laser-induced fluorescence imaging system developed to capture multispectral fluorescence emission images simultaneously from a relatively large target object is described. With an expanded, 355-nm Nd:YAG laser as the excitation source, the system captures fluorescence emission images in the blue, green, red, and far-red regions of the spectrum centered at 450, 550, 678, and 730 nm, respectively, from a 30-cm-diameter target area in ambient light. Images of apples and of pork meat artificially contaminated with diluted animal feces have demonstrated the versatility of fluorescence imaging techniques for potential applications in food safety inspection. Regions of contamination, including sites that were not readily visible to the human eye, could easily be identified from the images.
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Walls, Kelvin L.; Benke, Geza
2011-01-01
Increased use of fluorescent lighting as a climate change mitigation strategy may increase eye disease. The safe range of light to avoid exposing the eye to potentially damaging ultraviolet (UV) radiation is 2000 to 3500K and greater than 500 nanometers. Some fluorescent lights fall outside this safe range. Fluorescent lighting may increase UV-related eye diseases by up to 12% and, according to our calculations, may cause an additional 3000 cases of cataracts and 7500 cases of pterygia annually in Australia. Greater control of UV exposure from fluorescent lights is required. This may be of particular concern for aging populations in developed countries and countries in northern latitudes where there is a greater dependence on artificial lighting. PMID:22021286
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Protein amyloids develop an intrinsic fluorescence signature during aggregation†
Chan, Fiona T. S.; Kaminski Schierle, Gabriele S.; Kumita, Janet R.; Bertoncini, Carlos W.; Dobson, Christopher M.; Kaminski, Clemens F.
2017-01-01
We report observations of an intrinsic fluorescence in the visible range, which develops during the aggregation of a range of polypeptides, including the disease-related human peptides amyloid-β(1–40) and (1–42), lysozyme and tau. Characteristic fluorescence properties such as the emission lifetime and spectra were determined experimentally. This intrinsic fluorescence is independent of the presence of aromatic side-chain residues within the polypeptide structure. Rather, it appears to result from electronic levels that become available when the polypeptide chain folds into a cross-β sheet scaffold similar to what has been reported to take place in crystals. We use these findings to quantify protein aggregation in vitro by fluorescence imaging in a label-free manner. PMID:23420088
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Limitations of fluorescence spectroscopy to characterize organic matter in engineered systems
NASA Astrophysics Data System (ADS)
Korak, J.
2017-12-01
Fluorescence spectroscopy has been widely used to characterize dissolved organic matter (DOM) in engineered systems, such as drinking water, municipal wastewater and industrial water treatment. While fluorescence data collected in water treatment applications has led to the development of strong empirical relationships between fluorescence responses and process performance, the use of fluorescence to infer changes in the underlying organic matter chemistry is often oversimplified and applied out of context. Fluorescence only measures a small fraction of DOM as fluorescence quantum yields are less than 5% for many DOM sources. Relying on fluorescence as a surrogate for DOM presence, character or reactivity may not be appropriate for systems where small molecular weight, hydrophilic constituents unlikely to fluoresce are important. In addition, some methods rely on interpreting fluorescence signals at different excitation wavelengths as a surrogate for operationally-defined humic- and fulvic-acids in lieu of traditional XAD fractionation techniques, but these approaches cannot be supported by other lines of evidence considering natural abundance and fluorescence quantum yields of these fractions. These approaches also conflict with parallel factor analysis (PARAFAC), a statistical approach that routinely identifies fluorescence components with dual excitation behavior. Lastly, methods developed for natural systems are often applied out of context to engineered systems. Fluorescence signals characteristic of phenols or indoles are often interpreted as indicators for biological activity in natural systems due to fluorescent amino acids and peptides, but this interpretation is may not be appropriate in engineering applications where non-biological sources of phenolic functional groups may be present. This presentation explores common fluorescence interpretation approaches, discusses the limitations and provides recommendations related to engineered systems.
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NASA Astrophysics Data System (ADS)
Tian, Giselle; Zeng, Haishan; Zhao, Jianhua; Wu, Zhenguo; Al Jasser, Mohammed; Lui, Harvey; Mclean, David I.
2016-02-01
Porphyrins produced by Propionibacterium acnes represent the principal fluorophore associated with acne, and appear as orange-red luminescence under the Wood's lamp. Assessment of acne based on Wood's lamp (UV) or visible light illumination is limited by photon penetration depth and has limited sensitivity for earlier stage lesions. Inducing fluorescence with near infrared (NIR) excitation may provide an alternative way to assess porphyrin-related skin disorders. We discovered that under 785 nm CW laser excitation PpIX powder exhibits fluorescence emission in the shorter wavelength range of 600-715 nm with an intensity that is linearly dependent on the excitation power. We attribute this shorter wavelength emission to anti-Stokes fluorescence. Similar anti-Stokes fluorescence was also detected focally in all skin-derived samples containing porphyrins. Regular (Stokes) fluorescence was present under UV and visible light excitation on ex vivo nasal skin and sebum from uninflamed acne, but not on nose surface smears or sebum from inflamed acne. Co-registered CW laser-excited anti-Stokes fluorescence and fs laser-excited multi-photon fluorescence images of PpIX powder showed similar features. In the skin samples because of the anti-Stokes effect, the NIR-induced fluorescence was presumably specific for porphyrins since there appeared to be no anti-Stokes emission signals from other typical skin fluorophores such as lipids, keratins and collagen. Anti-Stokes fluorescence under NIR CW excitation is more sensitive and specific for porphyrin detection than UV- or visible light-excited regular fluorescence and fs laser-excited multi-photon fluorescence. This approach also has higher image contrast compared to NIR fs laser-based multi-photon fluorescence imaging. The anti-Stokes fluorescence of porphyrins within sebum could potentially be applied to detecting and targeting acne lesions for treatment via fluorescence image guidance.
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Motor Oil Classification Based on Time-Resolved Fluorescence
Mu, Taotao; Chen, Siying; Zhang, Yinchao; Guo, Pan; Chen, He; Meng, Fandong
2014-01-01
A time-resolved fluorescence (TRF) technique is presented for classifying motor oils. The system is constructed with a third harmonic Nd:YAG laser, a spectrometer, and an intensified charge coupled device (ICCD) camera. Steady-state and time-resolved fluorescence (TRF) measurements are reported for several motor oils. It is found that steady-state fluorescence is insufficient to distinguish the motor oil samples. Then contour diagrams of TRF intensities (CDTRFIs) are acquired to serve as unique fingerprints to identify motor oils by using the distinct TRF of motor oils. CDTRFIs are preferable to steady-state fluorescence spectra for classifying different motor oils, making CDTRFIs a particularly choice for the development of fluorescence-based methods for the discrimination and characterization of motor oils. The two-dimensional fluorescence contour diagrams contain more information, not only the changing shapes of the LIF spectra but also the relative intensity. The results indicate that motor oils can be differentiated based on the new proposed method, which provides reliable methods for analyzing and classifying motor oils. PMID:24988439
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Wang, Jixiang; Qiu, Hao; Shen, Hongqiang; Pan, Jianming; Dai, Xiaohui; Yan, Yongsheng; Pan, Guoqing; Sellergren, Börje
2016-11-15
Molecularly imprinted fluorescent polymers have shown great promise in biological or chemical separations and detections, due to their high stability, selectivity and sensitivity. In this work, molecularly imprinted fluorescent hollow nanoparticles, which could rapidly and efficiently detect λ-cyhalothrin (a toxic insecticide) in water samples, was reported. The molecularly imprinted fluorescent sensor showed excellent sensitivity (the limit of detection low to 10.26nM), rapid detection rate (quantitative detection of λ-cyhalothrin within 8min), regeneration ability (maintaining good fluorescence properties after 8 cycling operation) and appreciable selectivity over several structural analogs. Moreover, the fluorescent sensor was further used to detect λ-cyhalothrin in real samples form the Beijing-Hangzhou Grand Canal Water. Despite the relatively complex components of the environmental water, the molecularly imprinted fluorescent hollow nanosensor still showed good recovery, clearly demonstrating the potential value of this smart sensor nanomaterial in environmental monitoring. Copyright © 2016 Elsevier B.V. All rights reserved.
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Ghisaidoobe, Amar B. T.; Chung, Sang J.
2014-01-01
Förster resonance energy transfer (FRET) occurs when the distance between a donor fluorophore and an acceptor is within 10 nm, and its application often necessitates fluorescent labeling of biological targets. However, covalent modification of biomolecules can inadvertently give rise to conformational and/or functional changes. This review describes the application of intrinsic protein fluorescence, predominantly derived from tryptophan (λEX ∼ 280 nm, λEM ∼ 350 nm), in protein-related research and mainly focuses on label-free FRET techniques. In terms of wavelength and intensity, tryptophan fluorescence is strongly influenced by its (or the protein’s) local environment, which, in addition to fluorescence quenching, has been applied to study protein conformational changes. Intrinsic Förster resonance energy transfer (iFRET), a recently developed technique, utilizes the intrinsic fluorescence of tryptophan in conjunction with target-specific fluorescent probes as FRET donors and acceptors, respectively, for real time detection of native proteins. PMID:25490136
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Solvatochromic fluorescence characteristics of cinnamoyl pyrone derivatives
NASA Astrophysics Data System (ADS)
Benosmane, Nadjib; Boutemeur, Baya; Hamdi, Safouane M.; Hamdi, Maamar; Silva, Artur S. M.
2017-12-01
The solvatochromic fluorescence behavior of cinnamoyl pyrone derivatives has been studied in several polar and non-polar solvents. The fluorescence spectra of these compounds exhibit red shift from its absorption spectra and present an excellent correlation with solvent polarity. Cinnamoyl pyrones show a significant spectral shift in fluorescence emission as a function of water composition in binary aqueous solutions mixture. This change is due to the specific intermolecular hydrogen bonding of cinnamoyl pyrones with a molecules of water, due to the deactivation of the lowest excited singlet state of these compounds. The relative quantum yields are calculated. It is found that the quantum yields of the cinnamoyl pyrones vary with the change in the solvent polarity indicating the dependency of fluorescence properties on the solvent nature. It has been observed that the addition of water and pH medium can affect the fluorescence properties of cinnamoyl pyrones in ethanol. This study exhibited that due to the solvent sensitive emission, cinnamoyl pyrone derivatives are a good compound to be used as fluorescence probes.
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Airado-Rodríguez, Diego; Skaret, Josefine; Wold, Jens Petter
2010-05-12
This paper describes the fluorescent behavior of cod caviar paste, stored under different conditions, in terms of light exposure and concentration of oxygen in the headspace. Multivariate curve resolution was employed to decompose the overall fluorescence spectra into pure fluorescent components and calculate the relative concentrations of these components in the different samples. Profiles corresponding to protoporphyrin IX, photoprotoporphyrin, and fluorescent oxidation products were identified. Sensory evaluation, TBARS, and analysis of volatiles are typical methods employed in the routine analysis and quality control of such food. Successful calibration models were established between fluorescence and those routine methods. Correlation coefficients higher than 0.80 were found for 79% and higher than 0.90 for 50% of the assessed odors and flavors. For instance, R values of 0.94, and 0.96 were obtained for fresh and rancid flavors respectively, and 0.89 for TBARS. On the basis of these data, it can be argued that front-face fluorescence spectroscopy can substitute all of these expensive and tedious methodologies.
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Losi, Aba; Ternelli, Elena; Gärtner, Wolfgang
2004-01-01
The Bacillus subtilis protein YtvA, related to plant phototropins (phot), binds flavin mononucleotide (FMN) within the N-terminal light, oxygen and voltage (LOV) domain. The blue light-triggered photocycle of YtvA and phot involves the reversible formation of a covalent photoadduct between FMN and a cysteine (cys) residue. YtvA contains a single tryptophan, W103, localized on the LOV domain and conserved in all phot-LOV domains. In this study, we show that the fluorescence parameters of W103 in YtvA-LOV are markedly different from those observed in the full-length YtvA. The fluorescence quantum yields are ca 0.03 and 0.08, respectively. In YtvA-LOV, the maximum is redshifted (ca 345 vs 335 nm) and the average fluorescence lifetime shorter (2.7 vs 4.7 ns). These data indicate that W103 is located in a site of tight contact between the two domains of YtvA. In the FMN-cys adduct, selective excitation of W103 at 295 nm results in minimal changes of the fluorescence parameters with respect to the dark state. On 280 nm excitation, however, there is a detectable decrease in the fluorescence emitted from tyrosines, with concomitant increase in W103 fluorescence. This effect is reversible in the dark and might arise from a light-regulated energy transfer process from a yet unidentified tyrosine to W103.
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Assaf, Alexandre T; Zrnc, Tomislav A; Riecke, Björn; Wikner, Johannes; Zustin, Jozef; Friedrich, Reinhard E; Heiland, Max; Smeets, Ralf; Gröbe, Alexander
2014-07-01
The purpose of this study was to determine the potential of tissue fluorescence imaging by using Visually Enhanced Lesion Scope (VELscope) for the detection of osteonecrosis of the jaw induced by bisphosphonates (BRONJ). We investigated 20 patients (11 females and 9 males; mean age 74 years, standard deviation ± 6.4 years), over a period of 18 month with the diagnosis of BRONJ in this prospective cohort study. All patients received doxycycline as a fluorescending marker for osseous structures. VELscope has been used intraoperatively using the loss of fluorescence to detect presence of osteonecrosis. Osseous biopsies were taken to confirm definite histopathological diagnosis of BRONJ in each case. Diagnosis of BRONJ was confirmed for every patient. In all patients except one, VELscope was sufficient to differentiate between healthy and necrotic bone by visual fluorescence retention (VFR) and visual fluorescence loss (VFL). 19 cases out of a total of 20 showed no signs of recurrence of BRONJ during follow-up (mean 12 months, range 4-18 months). VELscope examination is a suitable tool to visualize necrotic areas of the bone in patients with bisphosphonate related osteonecrosis of the jaw. Loss of fluorescence in necrotic bone areas is useful intraoperatively as a tool for fluorescence-guided bone resection with relevant clinical interpretation. Copyright © 2013 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
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Kuhnt, Wolfgang; Holbourn, Ann; Xu, Jian; Opdyke, Bradley; De Deckker, Patrick; Röhl, Ursula; Mudelsee, Manfred
2015-01-06
The evolution of the Australian monsoon in relation to high-latitude temperature fluctuations over the last termination remains highly enigmatic. Here we integrate high-resolution riverine runoff and dust proxy data from X-ray fluorescence scanner measurements in four well-dated sediment cores, forming a NE-SW transect across the Timor Sea. Our records reveal that the development of the Australian monsoon closely followed the deglacial warming history of Antarctica. A minimum in riverine runoff documents dry conditions throughout the region during the Antarctic Cold Reversal (15-12.9 ka). Massive intensification of the monsoon coincided with Southern Hemisphere warming and intensified greenhouse forcing over Australia during the atmospheric CO2 rise at 12.9-10 ka. We relate the earlier onset of the monsoon in the Timor Strait (13.4 ka) to regional changes in landmass exposure during deglacial sea-level rise. A return to dryer conditions occurred between 8.1 and 7.3 ka following the early Holocene runoff maximum.
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NASA Astrophysics Data System (ADS)
Kuhnt, Wolfgang; Holbourn, Ann; Xu, Jian; Opdyke, Bradley; de Deckker, Patrick; Röhl, Ursula; Mudelsee, Manfred
2015-01-01
The evolution of the Australian monsoon in relation to high-latitude temperature fluctuations over the last termination remains highly enigmatic. Here we integrate high-resolution riverine runoff and dust proxy data from X-ray fluorescence scanner measurements in four well-dated sediment cores, forming a NE-SW transect across the Timor Sea. Our records reveal that the development of the Australian monsoon closely followed the deglacial warming history of Antarctica. A minimum in riverine runoff documents dry conditions throughout the region during the Antarctic Cold Reversal (15-12.9 ka). Massive intensification of the monsoon coincided with Southern Hemisphere warming and intensified greenhouse forcing over Australia during the atmospheric CO2 rise at 12.9-10 ka. We relate the earlier onset of the monsoon in the Timor Strait (13.4 ka) to regional changes in landmass exposure during deglacial sea-level rise. A return to dryer conditions occurred between 8.1 and 7.3 ka following the early Holocene runoff maximum.
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NASA Astrophysics Data System (ADS)
Mounier, S.; Nicolodelli, G.; Redon, R.; Milori, D. M. B. P.
2017-04-01
The front face fluorescence spectroscopy is often used to quantify chemicals in well-known matrices as it is a rapid and powerful technique, with no sample preparation. However it was not used to investigate extracted organic matter like humic substances. This work aims to fully investigate for the first time front face fluorescence spectroscopy response of a ternary system including boric acid, tryptophan and humic substances, and two binaries system containing quinine sulfate or humic substance in boric acid. Pure chemicals, boric acid, tryptophan, quinine sulfate and humic acid were mixed together in solid pellet at different contents from 0 to 100% in mass. The measurement of excitation emission matrix of fluorescence (3D fluorescence) and laser induced fluorescence were then done in the front face mode. Fluorescence matrices were decomposed using the CP/PARAFAC tools after scattering treatments. Results show that for 3D fluorescence there is no specific component for tryptophan and quinine sulfate, and that humic substances lead to a strong extinction effect for mixture containing quinine sulfate. Laser induced fluorescence gives a very good but non-specific related response for both quinine sulfate and tryptophan. No humic substances fluorescence response was found, but extinction effect is observed as for 3D fluorescence. This effect is stronger for quinine sulfate than for tryptophan. These responses were modeled using a simple absorbance versus emission model.
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Very High Spectral Resolution Imaging Spectroscopy: the Fluorescence Explorer (FLEX) Mission
NASA Technical Reports Server (NTRS)
Moreno, Jose F.; Goulas, Yves; Huth, Andreas; Middleton, Elizabeth; Miglietta, Franco; Mohammed, Gina; Nedbal, Ladislav; Rascher, Uwe; Verhoef, Wouter; Drusch, Matthias
2016-01-01
The Fluorescence Explorer (FLEX) mission has been recently selected as the 8th Earth Explorer by the European Space Agency (ESA). It will be the first mission specifically designed to measure from space vegetation fluorescence emission, by making use of very high spectral resolution imaging spectroscopy techniques. Vegetation fluorescence is the best proxy to actual vegetation photosynthesis which can be measurable from space, allowing an improved quantification of vegetation carbon assimilation and vegetation stress conditions, thus having key relevance for global mapping of ecosystems dynamics and aspects related with agricultural production and food security. The FLEX mission carries the FLORIS spectrometer, with a spectral resolution in the range of 0.3 nm, and is designed to fly in tandem with Copernicus Sentinel-3, in order to provide all the necessary spectral / angular information to disentangle emitted fluorescence from reflected radiance, and to allow proper interpretation of the observed fluorescence spatial and temporal dynamics.
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Hasani, E; Parravicini, J; Tartara, L; Tomaselli, A; Tomassini, D
2018-05-01
We propose an innovative experimental approach to estimate the two-photon absorption (TPA) spectrum of a fluorescent material. Our method develops the standard indirect fluorescence-based method for the TPA measurement by employing a line-shaped excitation beam, generating a line-shaped fluorescence emission. Such a configuration, which requires a relatively high amount of optical power, permits to have a greatly increased fluorescence signal, thus avoiding the photon counterdetection devices usually used in these measurements, and allowing to employ detectors such as charge-coupled device (CCD) cameras. The method is finally tested on a fluorescent isothiocyanate sample, whose TPA spectrum, which is measured with the proposed technique, is compared with the TPA spectra reported in the literature, confirming the validity of our experimental approach. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.
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Fluorescence characteristics in the deep waters of South Gulf of México.
Schifter, I; Sánchez-Reyna, G; González-Macías, C; Salazar-Coria, L; González-Lozano, C
2017-10-15
Vertical profiles of deep-water fluorescence determined by the chlorophyll sensor, polycyclic aromatic hydrocarbons, biomarkers, and other miscellaneous parameters measured in the southern Gulf of Mexico are reported. In the course of the survey, unexpected deep fluorescences were recorded (>1100m depth) in half of the 40 stations studied, a novel finding in this area of the Gulf. Currently, the deep-water fluorescence phenomenon is not completely understood, however we observe linear correlation between the fluorescence intensity and chlorophyll-α concentrations and coincidence of higher number of hydrocarbonoclastic bacteria in samples collected precisely in the deep-water fluorescence. This information is particularly interesting in relation to the Deepwater Horizon oil spill in 2010, in view that the aftermaths of the spill can be observed till today as oil plumes trapped in deep water layers that may disturb the natural water ecosystem. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Wang, Jixiang; Wang, Yunyun; Qiu, Hao; Sun, Lin; Dai, Xiaohui; Pan, Jianming; Yan, Yongsheng
2017-01-01
Fluorescent molecularly imprinted polymers have shown great promise in biological or chemical separations and detection, due to their high stability, selectivity and sensitivity. In this work, fluorescent molecularly imprinted microsphere was synthesized via precipitation polymerization, which could separate efficiently and rapidly detect τ-fluvalinate (a toxic insecticide) in water samples, was reported. The fluorescent imprinted sensor showed excellent stability, outstanding selectivity and the limit of detection low to 12.14 nM, good regeneration ability which still kept good sensitivity after 8 cycling experiments and fluorescence quenching mechanism was illustrated in details. In addition, the fluorescent sensor was further used to detect τ-fluvalinate in real samples from Taihu Lake. Despite the relatively complex components of the environment water, the fluorescent imprinted microspheres sitll showed good recovery, clearly demonstrating the potental value of this smart sensor nanomaterial in environment monitoring. PMID:28485402
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Quantitative, spectrally-resolved intraoperative fluorescence imaging
Valdés, Pablo A.; Leblond, Frederic; Jacobs, Valerie L.; Wilson, Brian C.; Paulsen, Keith D.; Roberts, David W.
2012-01-01
Intraoperative visual fluorescence imaging (vFI) has emerged as a promising aid to surgical guidance, but does not fully exploit the potential of the fluorescent agents that are currently available. Here, we introduce a quantitative fluorescence imaging (qFI) approach that converts spectrally-resolved data into images of absolute fluorophore concentration pixel-by-pixel across the surgical field of view (FOV). The resulting estimates are linear, accurate, and precise relative to true values, and spectral decomposition of multiple fluorophores is also achieved. Experiments with protoporphyrin IX in a glioma rodent model demonstrate in vivo quantitative and spectrally-resolved fluorescence imaging of infiltrating tumor margins for the first time. Moreover, we present images from human surgery which detect residual tumor not evident with state-of-the-art vFI. The wide-field qFI technique has broad implications for intraoperative surgical guidance because it provides near real-time quantitative assessment of multiple fluorescent biomarkers across the operative field. PMID:23152935
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Almasi, Sepideh; Xu, Xiaoyin; Ben-Zvi, Ayal; Lacoste, Baptiste; Gu, Chenghua; Miller, Eric L
2015-02-01
A novel approach to determine the global topological structure of a microvasculature network from noisy and low-resolution fluorescence microscopy data that does not require the detailed segmentation of the vessel structure is proposed here. The method is most appropriate for problems where the tortuosity of the network is relatively low and proceeds by directly computing a piecewise linear approximation to the vasculature skeleton through the construction of a graph in three dimensions whose edges represent the skeletal approximation and vertices are located at Critical Points (CPs) on the microvasculature. The CPs are defined as vessel junctions or locations of relatively large curvature along the centerline of a vessel. Our method consists of two phases. First, we provide a CP detection technique that, for junctions in particular, does not require any a priori geometric information such as direction or degree. Second, connectivity between detected nodes is determined via the solution of a Binary Integer Program (BIP) whose variables determine whether a potential edge between nodes is or is not included in the final graph. The utility function in this problem reflects both intensity-based and structural information along the path connecting the two nodes. Qualitative and quantitative results confirm the usefulness and accuracy of this method. This approach provides a mean of correctly capturing the connectivity patterns in vessels that are missed by more traditional segmentation and binarization schemes because of imperfections in the images which manifest as dim or broken vessels. Copyright © 2014 Elsevier B.V. All rights reserved.
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Wan, Yuhang; Carlson, John A.; Kesler, Benjamin A.; Peng, Wang; Su, Patrick; Al-Mulla, Saoud A.; Lim, Sung Jun; Smith, Andrew M.; Dallesasse, John M.; Cunningham, Brian T.
2016-01-01
A compact analysis platform for detecting liquid absorption and emission spectra using a set of optical linear variable filters atop a CMOS image sensor is presented. The working spectral range of the analysis platform can be extended without a reduction in spectral resolution by utilizing multiple linear variable filters with different wavelength ranges on the same CMOS sensor. With optical setup reconfiguration, its capability to measure both absorption and fluorescence emission is demonstrated. Quantitative detection of fluorescence emission down to 0.28 nM for quantum dot dispersions and 32 ng/mL for near-infrared dyes has been demonstrated on a single platform over a wide spectral range, as well as an absorption-based water quality test, showing the versatility of the system across liquid solutions for different emission and absorption bands. Comparison with a commercially available portable spectrometer and an optical spectrum analyzer shows our system has an improved signal-to-noise ratio and acceptable spectral resolution for discrimination of emission spectra, and characterization of colored liquid’s absorption characteristics generated by common biomolecular assays. This simple, compact, and versatile analysis platform demonstrates a path towards an integrated optical device that can be utilized for a wide variety of applications in point-of-use testing and point-of-care diagnostics. PMID:27389070
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NASA Astrophysics Data System (ADS)
Wan, Yuhang; Carlson, John A.; Kesler, Benjamin A.; Peng, Wang; Su, Patrick; Al-Mulla, Saoud A.; Lim, Sung Jun; Smith, Andrew M.; Dallesasse, John M.; Cunningham, Brian T.
2016-07-01
A compact analysis platform for detecting liquid absorption and emission spectra using a set of optical linear variable filters atop a CMOS image sensor is presented. The working spectral range of the analysis platform can be extended without a reduction in spectral resolution by utilizing multiple linear variable filters with different wavelength ranges on the same CMOS sensor. With optical setup reconfiguration, its capability to measure both absorption and fluorescence emission is demonstrated. Quantitative detection of fluorescence emission down to 0.28 nM for quantum dot dispersions and 32 ng/mL for near-infrared dyes has been demonstrated on a single platform over a wide spectral range, as well as an absorption-based water quality test, showing the versatility of the system across liquid solutions for different emission and absorption bands. Comparison with a commercially available portable spectrometer and an optical spectrum analyzer shows our system has an improved signal-to-noise ratio and acceptable spectral resolution for discrimination of emission spectra, and characterization of colored liquid’s absorption characteristics generated by common biomolecular assays. This simple, compact, and versatile analysis platform demonstrates a path towards an integrated optical device that can be utilized for a wide variety of applications in point-of-use testing and point-of-care diagnostics.
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Resonance fluorescence from an atom in a squeezed vacuum
NASA Astrophysics Data System (ADS)
Carmichael, H. J.; Lane, A. S.; Walls, D. F.
1987-06-01
The fluorescent spectrum for a two-level atom which is damped by a squeezed vacuum shows striking differences from the spectrum for ordinary resonance fluorescence. For strong coherent driving fields the Mollow triplet depends on the relative phase of the driving field and the squeezed vacuum field. The central peak may have either subnatural linewidth or supernatural linewidth depending on this phase. The mean atomic polarization also shows a phase sensitivity.
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1994-03-31
fluorescence intensity with temperature , which allows the fuel cn ce to be found directly from the acetaldehyde fluorescence. An alternative means of measuring... oxidizer . The measured quantities are used to form 17 a conserved scalar from which the mixtur fraction is determined in an iterative process. We have...turbulent nonpemIixed acetaklehyde flame. Acetaldehyde (CH3CHO) was chosen for its relatively high fluorescence yield and small variation of
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Deeg, Andreas A; Reiner, Anne M; Schmidt, Felix; Schueder, Florian; Ryazanov, Sergey; Ruf, Viktoria C; Giller, Karin; Becker, Stefan; Leonov, Andrei; Griesinger, Christian; Giese, Armin; Zinth, Wolfgang
2015-09-01
Special diphenyl-pyrazole compounds and in particular anle138b were found to reduce the progression of prion and Parkinson's disease in animal models. The therapeutic impact of these compounds was attributed to the modulation of α-synuclein and prion-protein aggregation related to these diseases. Photophysical and photochemical properties of the diphenyl-pyrazole compounds anle138b, anle186b and sery313b and their interaction with monomeric and aggregated α-synuclein were studied by fluorescence techniques. The fluorescence emission of diphenyl-pyrazole is strongly increased upon incubation with α-synuclein fibrils, while no change in fluorescence emission is found when brought in contact with monomeric α-synuclein. This points to a distinct interaction between diphenyl-pyrazole and the fibrillar structure with a high binding affinity (Kd=190±120nM) for anle138b. Several α-synuclein proteins form a hydrophobic binding pocket for the diphenyl-pyrazole compound. A UV-induced dehalogenation reaction was observed for anle138b which is modulated by the hydrophobic environment of the fibrils. Fluorescence of the investigated diphenyl-pyrazole compounds strongly increases upon binding to fibrillar α-synuclein structures. Binding at high affinity occurs to hydrophobic pockets in the fibrils. The observed particular fluorescence properties of the diphenyl-pyrazole molecules open new possibilities for the investigation of the mode of action of these compounds in neurodegenerative diseases. The high binding affinity to aggregates and the strong increase in fluorescence upon binding make the compounds promising fluorescence markers for the analysis of aggregation-dependent epitopes. Copyright © 2015 Elsevier B.V. All rights reserved.
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Magnetic luminescent nanoparticles as internal calibration for an immunoassay for ricin
NASA Astrophysics Data System (ADS)
Dosev, Dosi; Nichkova, Mikaela; Ma, Zhi-Ya; Gee, Shirley J.; Hammock, Bruce D.; Kennedy, Ian M.
2008-02-01
Fluorescence techniques rely on measurement of relative fluorescence units and require calibration to obtain reliable and comparable quantitative data. Fluorescent immunoassays are a very sensitive and convenient method of choice for rapid detection of biotoxins, such as ricin. Here we present the application of magnetic luminescent nanoparticles (MLNPs) with a magnetic core of Fe 3O 4 and a fluorescent shell of Eu:Gd IIO 3 as carriers for a nanobead-immunoassay for the detection of ricin with internal calibration. A sandwich immunoassay for ricin was performed on the surface of the MLNPs. The particles were functionalized with capture polyclonal antibodies. Anti-ricin antibodies labeled with Alexa Fluor dye were used as the detecting antibodies. After magnetic extraction, the amount of ricin bound to the particle surface was quantified and related to the fluorescence signal of the nanoparticles. In this new platform, the MLNPs have three main functions: (1) a probe for the specific extraction of the target analyte from the sample; (2) a carrier in the quantitative immunoassay with magnetic separation; and (3) an internal standard in the fluorescence measurement of the dye reporter. The MLNPs serve as an internal control for the total analysis including extraction and assay performance. This approach eliminates the experimental error inherent in particle extraction and measurement of absolute organic dye fluorescence intensities. All fluorescent measurements were performed in a microplate reader. The standard curve for ricin had a dynamic range from 20 ng/ml to 100 μg/ml with a detection limit of 5 ng/ml. The configuration that has been developed can be easily adapted to a high throughput miniaturized system.
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Origins of extrinsic variability in eukaryotic gene expression
NASA Astrophysics Data System (ADS)
Volfson, Dmitri; Marciniak, Jennifer; Blake, William J.; Ostroff, Natalie; Tsimring, Lev S.; Hasty, Jeff
2006-02-01
Variable gene expression within a clonal population of cells has been implicated in a number of important processes including mutation and evolution, determination of cell fates and the development of genetic disease. Recent studies have demonstrated that a significant component of expression variability arises from extrinsic factors thought to influence multiple genes simultaneously, yet the biological origins of this extrinsic variability have received little attention. Here we combine computational modelling with fluorescence data generated from multiple promoter-gene inserts in Saccharomyces cerevisiae to identify two major sources of extrinsic variability. One unavoidable source arising from the coupling of gene expression with population dynamics leads to a ubiquitous lower limit for expression variability. A second source, which is modelled as originating from a common upstream transcription factor, exemplifies how regulatory networks can convert noise in upstream regulator expression into extrinsic noise at the output of a target gene. Our results highlight the importance of the interplay of gene regulatory networks with population heterogeneity for understanding the origins of cellular diversity.
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Origins of extrinsic variability in eukaryotic gene expression
NASA Astrophysics Data System (ADS)
Volfson, Dmitri; Marciniak, Jennifer; Blake, William J.; Ostroff, Natalie; Tsimring, Lev S.; Hasty, Jeff
2006-03-01
Variable gene expression within a clonal population of cells has been implicated in a number of important processes including mutation and evolution, determination of cell fates and the development of genetic disease. Recent studies have demonstrated that a significant component of expression variability arises from extrinsic factors thought to influence multiple genes in concert, yet the biological origins of this extrinsic variability have received little attention. Here we combine computational modeling with fluorescence data generated from multiple promoter-gene inserts in Saccharomyces cerevisiae to identify two major sources of extrinsic variability. One unavoidable source arising from the coupling of gene expression with population dynamics leads to a ubiquitous noise floor in expression variability. A second source which is modeled as originating from a common upstream transcription factor exemplifies how regulatory networks can convert noise in upstream regulator expression into extrinsic noise at the output of a target gene. Our results highlight the importance of the interplay of gene regulatory networks with population heterogeneity for understanding the origins of cellular diversity.
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Water Quality Monitoring Using Tryptophan-like Fluorescence.
NASA Astrophysics Data System (ADS)
Hudson, N.; Urquhart, G.; Baker, A.; Ward, D.; Reynolds, D.; Carliell-Marquet, C.
2006-12-01
The Biochemical Oxygen Demand (BOD) test is recognised as being credible with over 90 years of application in water analysis. However it is easily affected by environmental constraints and requires the presence of a viable biological community. The BOD test takes 5-21 days and is laboratory based and so is unsuitable for rapid responses to potential pollution incidents. Analysis of fluorescence excitation emission matrices (EEM) of natural waters gives a rapid determination of the proportions of labile and refractory organic matter present. It facilitates a greater understanding of the oxygen depleting potential of organic matter in unfiltered samples in a shorter timescale than would be the case using BOD, the conventional water quality assessment method. The research presented assesses the relationship between 5-day BOD (BOD5) and the fluorescent amino acid tryptophan-like peak for a range of waters. The research is undertaken with a view to using fluorescence spectroscopy as an alternative to the BOD5 test for on-site monitoring or lab based, rapid indication of organic pollution in natural waters. A significant relationship is observed between the analytical parameters in line with the findings of previous research in which waste waters including synthetic sewage, and polluted surface waters were studied. This research demonstrates that for a large, variable data set tryptophan-like fluorescence is a strong indicator of BOD5 and may be used as a water quality monitoring tool particularly for high BOD5 samples.
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Gruber, David F; Gaffney, Jean P; Mehr, Shaadi; DeSalle, Rob; Sparks, John S; Platisa, Jelena; Pieribone, Vincent A
2015-01-01
We report the identification and characterization of two new members of a family of bilirubin-inducible fluorescent proteins (FPs) from marine chlopsid eels and demonstrate a key region of the sequence that serves as an evolutionary switch from non-fluorescent to fluorescent fatty acid-binding proteins (FABPs). Using transcriptomic analysis of two species of brightly fluorescent Kaupichthys eels (Kaupichthys hyoproroides and Kaupichthys n. sp.), two new FPs were identified, cloned and characterized (Chlopsid FP I and Chlopsid FP II). We then performed phylogenetic analysis on 210 FABPs, spanning 16 vertebrate orders, and including 163 vertebrate taxa. We show that the fluorescent FPs diverged as a protein family and are the sister group to brain FABPs. Our results indicate that the evolution of this family involved at least three gene duplication events. We show that fluorescent FABPs possess a unique, conserved tripeptide Gly-Pro-Pro sequence motif, which is not found in non-fluorescent fatty acid binding proteins. This motif arose from a duplication event of the FABP brain isoforms and was under strong purifying selection, leading to the classification of this new FP family. Residues adjacent to the motif are under strong positive selection, suggesting a further refinement of the eel protein's fluorescent properties. We present a phylogenetic reconstruction of this emerging FP family and describe additional fluorescent FABP members from groups of distantly related eels. The elucidation of this class of fish FPs with diverse properties provides new templates for the development of protein-based fluorescent tools. The evolutionary adaptation from fatty acid-binding proteins to fluorescent fatty acid-binding proteins raises intrigue as to the functional role of bright green fluorescence in this cryptic genus of reclusive eels that inhabit a blue, nearly monochromatic, marine environment.
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Multi-Modal Imaging in a Mouse Model of Orthotopic Lung Cancer
Patel, Priya; Kato, Tatsuya; Ujiie, Hideki; Wada, Hironobu; Lee, Daiyoon; Hu, Hsin-pei; Hirohashi, Kentaro; Ahn, Jin Young; Zheng, Jinzi; Yasufuku, Kazuhiro
2016-01-01
Background Investigation of CF800, a novel PEGylated nano-liposomal imaging agent containing indocyanine green (ICG) and iohexol, for real-time near infrared (NIR) fluorescence and computed tomography (CT) image-guided surgery in an orthotopic lung cancer model in nude mice. Methods CF800 was intravenously administered into 13 mice bearing the H460 orthotopic human lung cancer. At 48 h post-injection (peak imaging agent accumulation time point), ex vivo NIR and CT imaging was performed. A clinical NIR imaging system (SPY®, Novadaq) was used to measure fluorescence intensity of tumor and lung. Tumor-to-background-ratios (TBR) were calculated in inflated and deflated states. The mean Hounsfield unit (HU) of lung tumor was quantified using the CT data set and a semi-automated threshold-based method. Histological evaluation using H&E, the macrophage marker F4/80 and the endothelial cell marker CD31, was performed, and compared to the liposomal fluorescence signal obtained from adjacent tissue sections Results The fluorescence TBR measured when the lung is in the inflated state (2.0 ± 0.58) was significantly greater than in the deflated state (1.42 ± 0.380 (n = 7, p<0.003). Mean fluorescent signal in tumor was highly variable across samples, (49.0 ± 18.8 AU). CT image analysis revealed greater contrast enhancement in lung tumors (a mean increase of 110 ± 57 HU) when CF800 is administered compared to the no contrast enhanced tumors (p = 0.0002). Conclusion Preliminary data suggests that the high fluorescence TBR and CT tumor contrast enhancement provided by CF800 may have clinical utility in localization of lung cancer during CT and NIR image-guided surgery. PMID:27584018
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Multi-Modal Imaging in a Mouse Model of Orthotopic Lung Cancer.
Patel, Priya; Kato, Tatsuya; Ujiie, Hideki; Wada, Hironobu; Lee, Daiyoon; Hu, Hsin-Pei; Hirohashi, Kentaro; Ahn, Jin Young; Zheng, Jinzi; Yasufuku, Kazuhiro
2016-01-01
Investigation of CF800, a novel PEGylated nano-liposomal imaging agent containing indocyanine green (ICG) and iohexol, for real-time near infrared (NIR) fluorescence and computed tomography (CT) image-guided surgery in an orthotopic lung cancer model in nude mice. CF800 was intravenously administered into 13 mice bearing the H460 orthotopic human lung cancer. At 48 h post-injection (peak imaging agent accumulation time point), ex vivo NIR and CT imaging was performed. A clinical NIR imaging system (SPY®, Novadaq) was used to measure fluorescence intensity of tumor and lung. Tumor-to-background-ratios (TBR) were calculated in inflated and deflated states. The mean Hounsfield unit (HU) of lung tumor was quantified using the CT data set and a semi-automated threshold-based method. Histological evaluation using H&E, the macrophage marker F4/80 and the endothelial cell marker CD31, was performed, and compared to the liposomal fluorescence signal obtained from adjacent tissue sections. The fluorescence TBR measured when the lung is in the inflated state (2.0 ± 0.58) was significantly greater than in the deflated state (1.42 ± 0.380 (n = 7, p<0.003). Mean fluorescent signal in tumor was highly variable across samples, (49.0 ± 18.8 AU). CT image analysis revealed greater contrast enhancement in lung tumors (a mean increase of 110 ± 57 HU) when CF800 is administered compared to the no contrast enhanced tumors (p = 0.0002). Preliminary data suggests that the high fluorescence TBR and CT tumor contrast enhancement provided by CF800 may have clinical utility in localization of lung cancer during CT and NIR image-guided surgery.
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NASA Astrophysics Data System (ADS)
Raczka, B. M.; Bowling, D. R.; Lin, J. C.; Lee, J. E.; Yang, X.; Duarte, H.; Zuromski, L.
2017-12-01
Forests of the Western United States are prone to drought, temperature extremes, forest fires and insect infestation. These disturbance render carbon stocks and land-atmosphere carbon exchanges highly variable and vulnerable to change. Regional estimates of carbon exchange from terrestrial ecosystem models are challenged, in part, by a lack of net ecosystem exchange observations (e.g. flux towers) due to the complex mountainous terrain. Alternatively, carbon estimates based on light use efficiency models that depend upon remotely-sensed greenness indices are challenged due to a weak relationship with GPP during the winter season. Recent advances in the retrieval of remotely sensed solar induced fluorescence (SIF) have demonstrated a strong seasonal relationship between GPP and SIF for deciduous, grass and, to a lesser extent, conifer species. This provides an important opportunity to use remotely-sensed SIF to calibrate terrestrial ecosystem models providing a more accurate regional representation of biomass and carbon exchange across mountainous terrain. Here we incorporate both leaf-level fluorescence and leaf-to-canopy radiative transfer represented by the SCOPE model into CLM 4.5 (CLM-SIF). We simulate canopy level fluorescence at a sub-alpine forest site (Niwot Ridge, Colorado) and test whether these simulations reproduce remotely-sensed SIF from a satellite (GOME2). We found that the average peak SIF during the growing season (yrs 2007-2013) was similar between the model and satellite observations (within 15%); however, simulated SIF during the winter season was significantly greater than the satellite observations (5x higher). This implies that the fluorescence yield is overestimated by the model during the winter season. It is important that the modeled representation of seasonal fluorescence yield is improved to provide an accurate seasonal representation of SIF across the Western United States.
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Middelburg, T A; Hoy, C L; Neumann, H A M; Amelink, A; Robinson, D J
2015-07-01
Fluorescence measurements in the skin are very much affected by absorption and scattering but existing methods to correct for this are not applicable to superficial skin measurements. The first use of multiple-diameter single fiber reflectance (MDSFR) and single fiber fluorescence (SFF) spectroscopy in human skin was investigated. MDSFR spectroscopy allows a quantification of the full optical properties in superficial skin (μa, μs' and γ), which can next be used to retrieve the corrected - intrinsic - fluorescence of a fluorophore Qμa,x(f). Our goal was to investigate the importance of such correction for individual patients. We studied this in 22 patients undergoing photodynamic therapy (PDT) for actinic keratosis. The magnitude of correction of fluorescence was around 4 (for both autofluorescence and protoporphyrin IX). Moreover, it was variable between patients, but also within patients over the course of fractionated aminolevulinic acid PDT (range 2.7-7.5). Patients also varied in the amount of protoporphyrin IX synthesis, photobleaching percentages and resynthesis (>100× difference between the lowest and highest PpIX synthesis). The autofluorescence was lower in actinic keratosis than contralateral normal skin (0.0032 versus 0.0052; P<0.0005). Our results clearly demonstrate the importance of correcting the measured fluorescence for optical properties, because these vary considerably between individual patients and also during PDT. Protoporphyrin IX synthesis and photobleaching kinetics allow monitoring clinical PDT which facilitates individual-based PDT dosing and improvement of clinical treatment protocols. Furthermore, the skin autofluorescence can be relevant for diagnostic use in the skin, but it may also be interesting because of its association with several internal diseases. Copyright © 2015 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.
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Objective automated quantification of fluorescence signal in histological sections of rat lens.
Talebizadeh, Nooshin; Hagström, Nanna Zhou; Yu, Zhaohua; Kronschläger, Martin; Söderberg, Per; Wählby, Carolina
2017-08-01
Visual quantification and classification of fluorescent signals is the gold standard in microscopy. The purpose of this study was to develop an automated method to delineate cells and to quantify expression of fluorescent signal of biomarkers in each nucleus and cytoplasm of lens epithelial cells in a histological section. A region of interest representing the lens epithelium was manually demarcated in each input image. Thereafter, individual cell nuclei within the region of interest were automatically delineated based on watershed segmentation and thresholding with an algorithm developed in Matlab™. Fluorescence signal was quantified within nuclei, cytoplasms and juxtaposed backgrounds. The classification of cells as labelled or not labelled was based on comparison of the fluorescence signal within cells with local background. The classification rule was thereafter optimized as compared with visual classification of a limited dataset. The performance of the automated classification was evaluated by asking 11 independent blinded observers to classify all cells (n = 395) in one lens image. Time consumed by the automatic algorithm and visual classification of cells was recorded. On an average, 77% of the cells were correctly classified as compared with the majority vote of the visual observers. The average agreement among visual observers was 83%. However, variation among visual observers was high, and agreement between two visual observers was as low as 71% in the worst case. Automated classification was on average 10 times faster than visual scoring. The presented method enables objective and fast detection of lens epithelial cells and quantification of expression of fluorescent signal with an accuracy comparable with the variability among visual observers. © 2017 International Society for Advancement of Cytometry. © 2017 International Society for Advancement of Cytometry.
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Methods Improvement of the Fluorescent Penetrant Inspection (FPI) Process.
1980-10-01
also affect his ability. There has bieen recetnt eff’o to automiate V14. unfo~rtunatelyv, the humnan factors of’ F14I currentl lv cannot be replaced liY...control, and (6) human factors like variability of training, experience, and job interest. TECHNICAL APPROACH The objective of’ Phase II was to evaluate
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Sonoporation enhances liposome accumulation and penetration in tumors with low EPR.
Theek, Benjamin; Baues, Maike; Ojha, Tarun; Möckel, Diana; Veettil, Seena Koyadan; Steitz, Julia; van Bloois, Louis; Storm, Gert; Kiessling, Fabian; Lammers, Twan
2016-06-10
The Enhanced Permeability and Retention (EPR) effect is a highly variable phenomenon. To enhance EPR-mediated passive drug targeting to tumors, several different pharmacological and physical strategies have been evaluated over the years, including e.g. TNFα-treatment, vascular normalization, hyperthermia and radiotherapy. Here, we systematically investigated the impact of sonoporation, i.e. the combination of ultrasound (US) and microbubbles (MB), on the tumor accumulation and penetration of liposomes. Two different MB formulations were employed, and their ability to enhance liposome accumulation and penetration was evaluated in two different tumor models, which are both characterized by relatively low levels of EPR (i.e. highly cellular A431 epidermoid xenografts and highly stromal BxPC-3 pancreatic carcinoma xenografts). The liposomes were labeled with two different fluorophores, enabling in vivo computed tomography/fluorescence molecular tomography (CT-FMT) and ex vivo two-photon laser scanning microscopy (TPLSM). In both models, in spite of relatively high inter- and intra-individual variability, a trend towards improved liposome accumulation and penetration was observed. In treated tumors, liposome concentrations were up to twice as high as in untreated tumors, and sonoporation enhanced the ability of liposomes to extravasate out of the blood vessels into the tumor interstitium. These findings indicate that sonoporation may be a useful strategy for improving drug targeting to tumors with low EPR. Copyright © 2016 Elsevier B.V. All rights reserved.
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Regolith X-Ray Imaging Spectrometer (REXIS) Aboard the OSIRIS-REx Asteroid Sample Return Mission
NASA Astrophysics Data System (ADS)
Masterson, R. A.; Chodas, M.; Bayley, L.; Allen, B.; Hong, J.; Biswas, P.; McMenamin, C.; Stout, K.; Bokhour, E.; Bralower, H.; Carte, D.; Chen, S.; Jones, M.; Kissel, S.; Schmidt, F.; Smith, M.; Sondecker, G.; Lim, L. F.; Lauretta, D. S.; Grindlay, J. E.; Binzel, R. P.
2018-02-01
The Regolith X-ray Imaging Spectrometer (REXIS) is the student collaboration experiment proposed and built by an MIT-Harvard team, launched aboard NASA's OSIRIS-REx asteroid sample return mission. REXIS complements the scientific investigations of other OSIRIS-REx instruments by determining the relative abundances of key elements present on the asteroid's surface by measuring the X-ray fluorescence spectrum (stimulated by the natural solar X-ray flux) over the range of energies 0.5 to 7 keV. REXIS consists of two components: a main imaging spectrometer with a coded aperture mask and a separate solar X-ray monitor to account for the Sun's variability. In addition to element abundance ratios (relative to Si) pinpointing the asteroid's most likely meteorite association, REXIS also maps elemental abundance variability across the asteroid's surface using the asteroid's rotation as well as the spacecraft's orbital motion. Image reconstruction at the highest resolution is facilitated by the coded aperture mask. Through this operation, REXIS will be the first application of X-ray coded aperture imaging to planetary surface mapping, making this student-built instrument a pathfinder toward future planetary exploration. To date, 60 students at the undergraduate and graduate levels have been involved with the REXIS project, with the hands-on experience translating to a dozen Master's and Ph.D. theses and other student publications.
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NASA Astrophysics Data System (ADS)
Powell, Jesse R.; Ohman, Mark D.
2015-05-01
We report cross-frontal changes in the characteristics of plankton proxy variables measured by autonomous Spray ocean gliders operating within the Southern California Current System (SCCS). A comparison of conditions across the 154 positive frontal gradients (i.e., where density of the surface layer decreased in the offshore direction) identified from six years of continuous measurements showed that waters on the denser side of the fronts typically showed higher Chl-a fluorescence, shallower euphotic zones, and higher acoustic backscatter than waters on the less dense side. Transitions between these regions were relatively abrupt. For positive fronts the amplitude of Diel Vertical Migration (DVM), inferred from a 3-beam 750 kHz acoustic Doppler profiler, increased offshore of fronts and covaried with optical transparency of the water column. Average interbeam variability in acoustic backscatter also changed across many positive fronts within 3 depth strata (0-150 m, 150-400 m, and 400-500 m), revealing a front-related change in the acoustic scattering characteristics of the assemblages. The extent of vertical stratification of distinct scattering assemblages was also more pronounced offshore of positive fronts. Depth-stratified zooplankton samples collected by Mocness nets corroborated the autonomous measurements, showing copepod-dominated assemblages and decreased zooplankton body sizes offshore and euphausiid-dominated assemblages with larger median body sizes inshore of major frontal features.
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McCabe, Andrew J; Arnold, William A
2017-09-05
Dissolved organic matter (DOM) quantity and composition control the rate of formation (R f,T ) of triplet excited states of dissolved natural organic matter ( 3 DOM*) and the efficiency of 3 DOM* formation (the apparent quantum yield, AQY T ). Here, the reactivity of 3 DOM* in stormflow samples collected from watersheds with variable land covers is examined. Stormflow DOM reflects variability in DOM quantity and composition as a function of land cover and may be important in controlling the fate of cotransported pollutants. R f,T and AQY T were measured using 2,4,6-trimethylphenol in stormflow samples under simulated sunlight. The DOM source and composition was characterized using absorbance and fluorescence spectroscopies and high-resolution mass spectrometry. R f,T and the total rate of light absorption by the water samples (R a ) increased with the dissolved organic carbon (DOC) concentration. AQY T was independent of DOC concentration, but varied with DOM source: developed land cover (4-6%) ≈ open water > vegetated land cover (3%). AQY T was positively related to an index for microbial/algal DOM content and negatively related to DOM molecular weight, DOM aromaticity, and the content of polyphenols. This work demonstrates that TMP is an effective probe for the determination of R f,T and AQY T in whole water samples after accounting for the inhibition of TMP photodegradation by DOM.
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Medium effects on fluorescence of ciprofloxacin hydrochloride
NASA Astrophysics Data System (ADS)
Yang, Rui; Fu, Yan; Li, Long-Di; Liu, Jia-Ming
2003-10-01
The medium (pH, organic solvents, cyclodextrin (CD) or surfactants) effects on the fluorescence of ciprofloxacin hydrochloride (CPFX·HCl) were studied in detail. It is found that the three acid constants of ciprofloxacin (CPFX) are near to each other. Therefore the relation curve between pH and fluorescence intensity has no strident change and keeps relative stable in the pH range of 2-7. When pH was in the range of 5.5-6.0, the fluorescence intensity of CPFX reached the max. The kind and amount of organic solvent added to the luminescent system have various effects. Ethanol quenched fluorescence and the fluorescence excitation wavelength is red shift at first and then blue shift. Acetone has complicated effects on the fluorescence properties of CPFX·HCl solution. The experiment result shows that acetone is really a quencher when its volume content in the system is from 0 to 20%, but when its content is 90%, the signal intensity is unexpectedly one and a half times as much as that of no acetone. This means that there is a strong interaction between the acetone and CPFX; CPFX·H + could be included into the γ-CD but the capping effect is not notable. The effect of cationic surfactant cetyltrimethylammonium bromide and non-ionic surfactant TX-100 and TX-80 on CPFX fluorescence was unimpressive, but the anionic surfactant's effect is aberrant. The fluorescence intensity of CPFX·HCl solution experiences three stages of increasing, decreasing and increasing in turn, as sodium dodecyl sulfate is adding gradually. But for sodium lauryl sulfonate, there are only two stages of decreasing and increasing with the concentration increasing. It is problematic to illustrate clearly the effect mechanism of acetone and anionic surfactant at present. Undoubtedly, the experimental results in this paper should be useful in practice works and the research is worth studying still further.
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Fluorescent Approaches to High Throughput Crystallography
NASA Technical Reports Server (NTRS)
Pusey, Marc L.; Forsythe, Elizabeth
2005-01-01
X-ray crystallography remains the primary method for determining the structure of macromolecules. The first requirement is to have crystals, and obtaining them is often the rate-limiting step. The numbers of crystallization trials that are set up for any one protein for structural genomics, and the rate at which they are being set up, now overwhelm the ability for strictly human analysis of the results. Automated analysis methods are now being implemented with varying degrees of success, but these typically cannot reliably extract intermediate results. By covalently modifying a subpopulation, 51%, of a macromolecule solution with a fluorescent probe, the labeled material will add to a growing crystal as a microheterogeneous growth unit. Labeling procedures can be readily incorporated into the final stages of purification. The covalently attached probe will concentrate in the crystal relative to the solution, and under fluorescent illumination the crystals show up as bright objects against a dark background. As crystalline packing is more dense than amorphous precipitate, the fluorescence intensity can be used as a guide in distinguishing different types of precipitated phases, even in the absence of obvious crystalline features, widening the available potential lead conditions in the absence of clear hits. Non-protein structures, such as salt crystals, will not incorporate the probe and will not show up under fluorescent illumination. Also, brightly fluorescent crystals are readily found against less fluorescent precipitated phases, which under white light illumination may serve to obscure the crystals. Automated image analysis to find crystals should be greatly facilitated, without having to first define crystallization drop boundaries and by having the protein or protein structures all that show up. The trace fluorescently labeled crystals will also emit with sufficient intensity to aid in the automation of crystal alignment using relatively low cost optics, further increasing throughput at synchrotrons. This presentation will focus on the methodology for fluorescent labeling, the crystallization results, and the effects of the trace labeling on the crystal quality.
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Fluorescent Approaches to High Throughput Crystallography
NASA Technical Reports Server (NTRS)
Minamitani, Elizabeth Forsythe; Pusey, Marc L.
2004-01-01
X-ray crystallography remains the primary method for determining the structure of macromolecules. The first requirement is to have crystals, and obtaining them is often the rate-limiting step. The numbers of crystallization trials that are set up for any one protein for structural genomics, and the rate at which they are being set up, now overwhelm the ability for strictly human analysis of the results. Automated analysis methods are now being implemented with varying degrees of success, but these typically cannot reliably extract intermediate results. By covalently modifying a subpopulation, less than or = 1%, of a macromolecule solution with a fluorescent probe, the labeled material will add to a growing crystal as a microheterogeneous growth unit. Labeling procedures can be readily incorporated into the final stages of a macromolecules purification. The covalently attached probe will concentrate in the crystal relative to the solution, and under fluorescent illumination the crystals will show up as bright objects against a dark background. As crystalline packing is more dense than amorphous precipitate, the fluorescence intensity can be used as a guide in distinguishing different types of precipitated phases, even in the absence of obvious crystalline features, widening the available potential lead conditions in the absence of clear "bits." Non-protein structures, such as salt crystals, will not incorporate the probe and will not show up under fluorescent illumination. Also, brightly fluorescent crystals are readily found against less fluorescent precipitated phases, which under white light illumination may serve to obscure the crystals. Automated image analysis to find crystals should be greatly facilitated, without having to first define crystallization drop boundaries and by having the protein or protein structures all that show up. The trace fluorescently labeled crystals will also emit with sufficient intensity to aid in the automation of crystal alignment using relatively low cost optics, further increasing throughput at synchrotrons. This presentation will focus on the methodology for fluorescent labeling, the crystallization results, and the effects of the trace labeling on the crystal quality.
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Fluorescent Approaches to High Throughput Crystallography
NASA Technical Reports Server (NTRS)
Pusey, Marc L.; Forsythe, Elizabeth; Achari, Amiruddha
2005-01-01
X-ray crystallography remains the primary method for determining the structure of macromolecules. The first requirement is to have crystals, and obtaining them is often the rate-limiting step. The numbers of crystallization trials that are set up for any one protein for structural genomics, and the rate at which they are being set up, now overwhelm the ability for strictly human analysis of the results. Automated analysis methods are now being implemented with varying degrees of success, but these typically cannot reliably extract intermediate results. By covalently modifying a subpopulation, less than or = 1 %, of a macromolecule solution with a fluorescent probe, the labeled material will add to a growing crystal as a microheterogeneous growth unit. Labeling procedures can be readily incorporated into the final stages of purification. The covalently attached probe will concentrate in the crystal relative to the solution, and under fluorescent illumination the crystals show up as bright objects against a dark background. As crystalline packing is more dense than amorphous precipitate, the fluorescence intensity can be used as a guide in distinguishing different types of precipitated phases, even in the absence of obvious crystalline features, widening the available potential lead conditions in the absence of clear "hits." Non-protein structures, such as salt crystals, will not incorporate the probe and will not show up under fluorescent illumination. Also, brightly fluorescent crystals are readily found against less fluorescent precipitated phases, which under white light illumination may serve to obscure the crystals. Automated image analysis to find crystals should be greatly facilitated, without having to first define crystallization drop boundaries and by having the protein or protein structures all that show up. The trace fluorescently labeled crystals will also emit with sufficient intensity to aid in the automation of crystal alignment using relatively low cost optics, further increasing throughput at synchrotrons. Preliminary experiments show that the presence of the fluorescent probe does not affect the nucleation process or the quality of the X-ray data obtained.
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Fluorescent Approaches to High Throughput Crystallography
NASA Technical Reports Server (NTRS)
Pusey, Marc L.; Forsythe, Elizabeth
2004-01-01
X-ray crystallography remains the primary method for determining the structure of macromolecules. The first requirement is to have crystals, and obtaining them is often the rate-limiting step. The numbers of crystallization trials that are set up for any one protein for structural genomics, and the rate at which they are being set up, now overwhelm the ability for strictly human analysis of the results. Automated analysis methods are now being implemented with varying degrees of success, but these typically can not reliably extract intermediate results. By covalently modifying a subpopulation, less than or = 1%, of a macromolecule solution with a fluorescent probe, the labeled material will add to a growing crystal as a microheterogeneous growth unit. Labeling procedures can be readily incorporated into the final stages of purification. The covalently attached probe will concentrate in the crystal relative to the solution, and under fluorescent illumination the crystals show up as bright objects against a dark background. As crystalline packing is more dense than amorphous precipitate, the fluorescence intensity can be used as a guide in distinguishing different types of precipitated phases, even in the absence of obvious crystalline features, widening the available potential lead conditions in the absence of clear "hits." Non-protein structures, such as salt crystals, will not incorporate the probe and will not show up under fluorescent illumination. Also, brightly fluorescent crystals are readily found against less fluorescent precipitated phases, which under white light illumination may serve to obscure the crystals. Automated image analysis to find crystals should be greatly facilitated, without having to first define crystallization drop boundaries and by having the protein or protein structures all that show up. The trace fluorescently labeled crystals will also emit with sufficient intensity to aid in the automation of crystal alignment using relatively low cost optics, further increasing throughput at synchrotrons. This presentation will focus on the methodology for fluorescent labeling, the crystallization results, and the effects of the trace labeling on the crystal quality.
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Automatic tracking of cells for video microscopy in patch clamp experiments
2014-01-01
Background Visualisation of neurons labeled with fluorescent proteins or compounds generally require exposure to intense light for a relatively long period of time, often leading to bleaching of the fluorescent probe and photodamage of the tissue. Here we created a technique to drastically shorten light exposure and improve the targeting of fluorescent labeled cells that is specially useful for patch-clamp recordings. We applied image tracking and mask overlay to reduce the time of fluorescence exposure and minimise mistakes when identifying neurons. Methods Neurons are first identified according to visual criteria (e.g. fluorescence protein expression, shape, viability etc.) and a transmission microscopy image Differential Interference Contrast (DIC) or Dodt contrast containing the cell used as a reference for the tracking algorithm. A fluorescence image can also be acquired later to be used as a mask (that can be overlaid on the target during live transmission video). As patch-clamp experiments require translating the microscope stage, we used pattern matching to track reference neurons in order to move the fluorescence mask to match the new position of the objective in relation to the sample. For the image processing we used the Open Source Computer Vision (OpenCV) library, including the Speeded-Up Robust Features (SURF) for tracking cells. The dataset of images (n = 720) was analyzed under normal conditions of acquisition and with influence of noise (defocusing and brightness). Results We validated the method in dissociated neuronal cultures and fresh brain slices expressing Enhanced Yellow Fluorescent Protein (eYFP) or Tandem Dimer Tomato (tdTomato) proteins, which considerably decreased the exposure to fluorescence excitation, thereby minimising photodamage. We also show that the neuron tracking can be used in differential interference contrast or Dodt contrast microscopy. Conclusion The techniques of digital image processing used in this work are an important addition to the set of microscopy tools used in modern electrophysiology, specially in experiments with neuron cultures and brain slices. PMID:24946774
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Automatic tracking of cells for video microscopy in patch clamp experiments.
Peixoto, Helton M; Munguba, Hermany; Cruz, Rossana M S; Guerreiro, Ana M G; Leao, Richardson N
2014-06-20
Visualisation of neurons labeled with fluorescent proteins or compounds generally require exposure to intense light for a relatively long period of time, often leading to bleaching of the fluorescent probe and photodamage of the tissue. Here we created a technique to drastically shorten light exposure and improve the targeting of fluorescent labeled cells that is specially useful for patch-clamp recordings. We applied image tracking and mask overlay to reduce the time of fluorescence exposure and minimise mistakes when identifying neurons. Neurons are first identified according to visual criteria (e.g. fluorescence protein expression, shape, viability etc.) and a transmission microscopy image Differential Interference Contrast (DIC) or Dodt contrast containing the cell used as a reference for the tracking algorithm. A fluorescence image can also be acquired later to be used as a mask (that can be overlaid on the target during live transmission video). As patch-clamp experiments require translating the microscope stage, we used pattern matching to track reference neurons in order to move the fluorescence mask to match the new position of the objective in relation to the sample. For the image processing we used the Open Source Computer Vision (OpenCV) library, including the Speeded-Up Robust Features (SURF) for tracking cells. The dataset of images (n = 720) was analyzed under normal conditions of acquisition and with influence of noise (defocusing and brightness). We validated the method in dissociated neuronal cultures and fresh brain slices expressing Enhanced Yellow Fluorescent Protein (eYFP) or Tandem Dimer Tomato (tdTomato) proteins, which considerably decreased the exposure to fluorescence excitation, thereby minimising photodamage. We also show that the neuron tracking can be used in differential interference contrast or Dodt contrast microscopy. The techniques of digital image processing used in this work are an important addition to the set of microscopy tools used in modern electrophysiology, specially in experiments with neuron cultures and brain slices.
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Fluorescent Applications to Crystallization
NASA Technical Reports Server (NTRS)
Pusey, Marc L.; Forsythe, Elizabeth; Achari, Aniruddha
2006-01-01
By covalently modifying a subpopulation, less than or equal to 1%, of a macromolecule with a fluorescent probe, the labeled material will add to a growing crystal as a microheterogeneous growth unit. Labeling procedures can be readily incorporated into the final stages of purification, and tests with model proteins have shown that labeling u to 5 percent of the protein molecules does not affect the X-ray data quality obtained . The presence of the trace fluorescent label gives a number of advantages. Since the label is covalently attached to the protein molecules, it "tracks" the protein s response to the crystallization conditions. The covalently attached probe will concentrate in the crystal relative to the solution, and under fluorescent illumination crystals show up as bright objects against a darker background. Non-protein structures, such as salt crystals, do not show up under fluorescent illumination. Crystals have the highest protein concentration and are readily observed against less bright precipitated phases, which under white light illumination may obscure the crystals. Automated image analysis to find crystals should be greatly facilitated, without having to first define crystallization drop boundaries as the protein or protein structures is all that shows up. Fluorescence intensity is a faster search parameter, whether visually or by automated methods, than looking for crystalline features. Preliminary tests, using model proteins, indicates that we can use high fluorescence intensity regions, in the absence of clear crystalline features or "hits", as a means for determining potential lead conditions. A working hypothesis is that more rapid amorphous precipitation kinetics may overwhelm and trap more slowly formed ordered assemblies, which subsequently show up as regions of brighter fluorescence intensity. Experiments are now being carried out to test this approach using a wider range, of proteins. The trace fluorescently labeled crystals will also emit with sufficient intensity to aid in the automation of crystal alignment using relatively low cost optics, further increasing throughput at synchrotrons.
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Observation of nanosecond laser induced fluorescence of in vitro seawater phytoplankton
DOE Office of Scientific and Technical Information (OSTI.GOV)
Bensky, Thomas J.; Clemo, Lisa; Gilbert, Chris
2008-08-01
Seawater has been irradiated using a train of 70 ns flashes from a 440 nm laser source. This wavelength is on resonance with the blue absorption peak of Chlorophyll pigment associated with the photosystem of in vitro phytoplankton. The resulting fluorescence at 685 nm is instantaneously recorded during each laser pulse using a streak camera. Delayed fluorescence is observed, yielding clues about initiation of the photosynthetic process on a nanosecond time scale. Further data processing allows for determination of the functional absorption cross section, found to be 0.0095 ?{sup 2}, which is the first reporting of this number for inmore » vitro phytoplankton. Unlike other flash-pump studies of Chlorophyll, using a LED or flashlamp-based sources, the short laser pulse used here does not reveal any pulse-to-pulse hysteresis (i.e., variable fluorescence), indicating that the laser pulses used here are not able to drive the photosynthetic process to completion. This is attributed to competition from a back reaction between the photoexcited photosystem II and the intermediate electron acceptor. The significance of this work as a new type of deployable ocean fluorimeter is discussed, and it is believed the apparatus will have applications in thin-layer phytoplankton research.« less
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Pandžić, Elvis; Abu-Arish, Asmahan; Whan, Renee M; Hanrahan, John W; Wiseman, Paul W
2018-02-16
Molecular, vesicular and organellar flows are of fundamental importance for the delivery of nutrients and essential components used in cellular functions such as motility and division. With recent advances in fluorescence/super-resolution microscopy modalities we can resolve the movements of these objects at higher spatio-temporal resolutions and with better sensitivity. Previously, spatio-temporal image correlation spectroscopy has been applied to map molecular flows by correlation analysis of fluorescence fluctuations in image series. However, an underlying assumption of this approach is that the sampled time windows contain one dominant flowing component. Although this was true for most of the cases analyzed earlier, in some situations two or more different flowing populations can be present in the same spatio-temporal window. We introduce an approach, termed velocity landscape correlation (VLC), which detects and extracts multiple flow components present in a sampled image region via an extension of the correlation analysis of fluorescence intensity fluctuations. First we demonstrate theoretically how this approach works, test the performance of the method with a range of computer simulated image series with varying flow dynamics. Finally we apply VLC to study variable fluxing of STIM1 proteins on microtubules connected to the plasma membrane of Cystic Fibrosis Bronchial Epithelial (CFBE) cells. Copyright © 2018 Elsevier Inc. All rights reserved.
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Elliott, D.G.; Barila, T.Y.
1987-01-01
We developed a rapid method for detecting and quantifying the pathogen Renibacterium salmoninarum in coelomic fluid of spring chinook salmon (Oncorhynchus tshawytscha) by concentrating the bacteria on 0.2-μm polycarbonate filters and staining them with specific fluorescein-labeled antibody. Centrifugation of samples and resuspension of the sedimented material in phosphate-buffered saline containing Triton X-100 increased the ease of filtration. Background fluorescence was reduced by counterstaining filters with Eriochrome black T. Postfiltration staining, rinsing, and counterstaining were done in the syringe-mounted filter holders, reducing handling of the filters and possible loss of bacteria. The number of bacteria detected by the filtration – fluorescent antibody technique in a broth culture of R. salmoninarum ranged from 6.7 × 107to7.6 × 107/mL and was slightly higher than that determined by plate count (9.6 × 106/mL). Increasing the sample dilution or decreasing the number of microscope fields examined generally increased the variability of filter counts of R. salmoninarum. Using the filtration – fluorescent antibody technique, we detected the bacterium in the coelomic fluid of 85% of spawning female spring chinook salmon sampled from a hatchery population.
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Evaluating and operationalizing an environmental auditing program: a pilot study.
Gordon, Laura; Bruce, Natalie; Suh, Kathryn N; Roth, Virginia
2014-07-01
Environmental auditing is an important tool to ensure consistent and effective cleaning. Our pilot study compared an alcohol-based fluorescent marking product and an adenosine-5'-triphosphate bioluminescence product for use in an environmental auditing program to determine which product was more practical and acceptable to users. Both products were tested on 15 preselected high touch objects in randomly selected patient rooms, following regular daily cleaning. A room was considered a "pass" if ≥80% of surfaces were adequately cleaned as defined by manufacturers' guidelines. A qualitative survey assessed user preference and operational considerations. Using fluorescent marking, 9 of 37 patient rooms evaluated (24%) were considered a "pass" after daily cleaning. Using adenosine-5'-triphosphate bioluminescence, 21 of 37 patient rooms passed (57%). There was great variability in results between different high touch objects. Eighty percent of users preferred the alcohol-based fluorescent marking product because it provided an effective visual aid to coach staff on proper cleaning techniques and allowed simple and consistent application. Environmental auditing using translucent, alcohol-based fluorescent marking best met the requirements of our organization. Our results reinforce the importance of involving a multidisciplinary team in evaluating and operationalizing an environmental auditing program. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.
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Quantitative fluorescence angiography for neurosurgical interventions.
Weichelt, Claudia; Duscha, Philipp; Steinmeier, Ralf; Meyer, Tobias; Kuß, Julia; Cimalla, Peter; Kirsch, Matthias; Sobottka, Stephan B; Koch, Edmund; Schackert, Gabriele; Morgenstern, Ute
2013-06-01
Present methods for quantitative measurement of cerebral perfusion during neurosurgical operations require additional technology for measurement, data acquisition, and processing. This study used conventional fluorescence video angiography--as an established method to visualize blood flow in brain vessels--enhanced by a quantifying perfusion software tool. For these purposes, the fluorescence dye indocyanine green is given intravenously, and after activation by a near-infrared light source the fluorescence signal is recorded. Video data are analyzed by software algorithms to allow quantification of the blood flow. Additionally, perfusion is measured intraoperatively by a reference system. Furthermore, comparing reference measurements using a flow phantom were performed to verify the quantitative blood flow results of the software and to validate the software algorithm. Analysis of intraoperative video data provides characteristic biological parameters. These parameters were implemented in the special flow phantom for experimental validation of the developed software algorithms. Furthermore, various factors that influence the determination of perfusion parameters were analyzed by means of mathematical simulation. Comparing patient measurement, phantom experiment, and computer simulation under certain conditions (variable frame rate, vessel diameter, etc.), the results of the software algorithms are within the range of parameter accuracy of the reference methods. Therefore, the software algorithm for calculating cortical perfusion parameters from video data presents a helpful intraoperative tool without complex additional measurement technology.
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Peng, Lu; Wei, Ruirui; Li, Kai; Zhou, Zhaojuan; Song, Panshu; Tong, Aijun
2013-04-07
A novel fluorescent probe 1 is reported here with ratiometric response to hydrophobic proteins (casein) or proteins with hydrophobic pockets (BSA, HSA) through hydrophobic interaction. Probe 1 underwent deprotonation in aqueous solution at pH 7.4 and emitted blue fluorescence at 436 nm. Upon the addition of BSA, HSA or casein, the aggregation-induced emission fluorescence of 1 at 518 nm was turned on. The fluorescence intensity ratio, I518/I436 was linearly related to the concentrations of these proteins. The detection limits for BSA, HSA and casein based on IUPAC (CDL = 3Sb m(-1)) were 16.2 μg mL(-1), 10.5 μg mL(-1) and 5.7 μg mL(-1), respectively.
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Unfolding mechanism of lysozyme in various urea solutions: Insights from fluorescence spectroscopy
NASA Astrophysics Data System (ADS)
Chen, Bang; Zhang, Hongjia; Xi, Wenying; Zhao, Liqing; Liang, Li; Chen, Yantao
2014-11-01
Fluorescence spectroscopic technique is very popular in exploring the folding/unfolding process of proteins. In this paper, unfolding process of hen egg-white lysozyme was investigated in various denaturing solutions. Firstly, polymer solution theory was employed to comprehend the dependence of fluorescence quenching effect on protein concentration, and dynamic contact concentration was suggested as a critical value for related fluorescence experiment. Secondly, it was found that urea alone could not completely unfold lysozyme but did when together with DTT or HCl. Lysozyme was destabilized in concentrated urea solution, but still could maintain its spatial structure. Phase diagram of fluorescence intensities revealed that HCl could enhance the denaturing capacity of urea, resulting in the emergence of intermediate state in the thermodynamic unfolding process of lysozyme.