INDEX fluorescence

Fig. 11.7 Effect of HU on ml-CAM-1 expression in the TrHBMEC (a) and EA-hy 926 (b). These cells were incubated with HU 250 pM for 48 h with or without 100 U mb of TNFaand IFNy. mlCAM-1 cellular expression was analyzed by flow cytometry. Results are the Mean Fluorescent Index (MFI) of one representative experiment, with overall trend in three other independent experiments being comparable. Parallel estimation of slCAM-1 release in the culture supernatant of TrHBMEC cells (6 independent experiments) revealed that without cytokines sICAM-1 was not detectable in the supernatant for the basal conditions. The results of HU-treated cells (c) in the presence of cytokines showed a significant increase in release of slCAM-1 (p <0.05).

Measurement of the Spectral Intensity For measurement, we use the residual 360 nm peak as internal reference (23). The fluorescence intensity is recorded in the standard method at 430 nm. Fluorescence index is defined by us as the ratio 1430/1350 This is measured at every sampling period for both the blank, the control without antioxidant, and the antioxidant-treated sample. Relative mean deviation of replicate measurements (repositioning the plate) is +5%. 

In the Front Range of the Rocky Mountains, the N enrichment of alpine catchments from increased atmospheric N deposition from agricultural and urban development on the plains is an important environmental and resource issue (Williams et al., 1996). The difference in N content (about 0.5-1.0% for terrestrially derived DOM vs. about 2-3% for microbially derived DOM) could be significant in terms of estimating the contribution of dissolved fulvic acid flux to the yield of N from alpine and subalpine catchments in the Rocky Mountains. The example for this alpine catchment illustrates the potential usefulness of the fluorescence index in field studies addressing applied issues related to environmental management. 

Perrette, Y., Delannoy, J.-J., Desmet, M., Lignier, V. Destobmes, J.-L. (2005) Speleothem organic matter content imaging. The use of a fluorescence index to characterize the maximum emission wavelength. Chemical Geology 214, 193-208. 

Figure 7. CDOM fluorescence of water from two lakes (Hargreaves, unpublished) emission scans for excitation at 370 nm (Shimadzu 551 fluorometer), before and after subtraction of water blank. Samples deionized water (DIW), L. Giles water (ca. 1 g m DOC), L. Lacawac water (ca. 5 g m DOC) The Raman scattering peak at 417 nm represents a shift in wavenumber by 3400 cm from the excitation wavenumber. The broad peak is contributed predominantly by the fulvic acid fraction of DOM. The peak wavelength and fluorescence index ratio for these samples (L. Giles, 452 nm peak and ratio = 1.5 L. Lacawac, 455 mn peak and ratio = 1.4) suggest a slight difference in CDOM...

The examination of DOM fluorescence in freshwater ecosystems with respect to tanporal variability has been undertaken at a range of time scales from diurnal to seasonal. Seasonal variation in humic-like and protein-like fluorescence has been used to show increasing autochthonous inputs (i.e peak in protein-like fluorescence), increasing allocthonous inputs (i.e., peak in humic-like fluorescence), and thus the dominance of biological or hydrological controls on the ecosystem (Jaffe et al., 2008 Miller and McKnight, 2010). Simple DOM measurements such as the fluorescence index (ratio of Aem 470 to 520 nm at a... 

Figure 3.8. Relationships between indices of DOM character and landcover. The best predictors for fluorescence index (a,b). (Reprinted from Wilson and Xenopoulos, 2009, by permission from Macmillan Publishers Ltd Nature Geoscience.)...

Fluorescence Index to identify Precursor Material in Freshwater DOM (FI)... 

Figure 9.6. Plot of McKnight et al. (2001) fluorescence index (FI) vs. % aromaticity for a variety of isolated fulvic acid samples. The % aromaticity was calculated using C-NMR as the ratio of the area of the aromatic carbon region to the total area of the spectrum. There is a strong correlation between FI and % aromaticity (linear regression equation is y = -O.Qllx + 2.1 (B - = 0.85), and the power function regression is y = 3.94 x where x=% aromaticity and y = FI). Note that while Deer Creek (DC) flows into Snake River (SR), the aromaticity drops due to the aromatic fulvic acids sorbing to iron oxide in the streambed, but there is httle change in the FI, indicating a robustness of the index.

Figure 9.7. Two components of the Cory and McKnight (2005) PARAFAC model that have spectral properties similar to semiquinones (SQl and SQ2) explain the variation in the McKnight et al. (2001) fluorescence index (FI). The SQ2 component is resolved in a model using only samples from Antarctic lakes, indicating it is likely microbial in origin. As the portion of SQ2 to the total of SQl -i-SQ2 falls, so does the FI, and a lower FI is associated with less microbially derived material. (From Cory and McKnight, 2005.)...

The Development of a Fluorescence Index to Measure Organic Matter Humification Preserved in Cave Stalagmites and Create Long-Term Records... 

Figure 9.12. Linear regression between Perrette et al. (2005) fluorescence index (the ratio of emitted fluorescence at 514-457 nm) and the wavelength of maximum fluorescence intensity Excitation wavelength is 364 nm using a laser hght source. Lower regression is for aqueous samples from soil and groundwater, grey shaded regression is for geological samples. (From Perrette et al., 2005.)...

Figure 9.13. Seasonal variation in (a) chlorophyll a, (b) DOC, (c) percentage fulvic acid, (d) whole water (solid line) and fulvic acid (dashed hue) McKnight Fluorescence Index (FI), and (e) whole water redox index (RI) at the outlet to Green Lake 4, an alpine lake in the Colorado Rocky Mountains. The vertical dashed lines indicate the sustained rain event, and the shaded areas represent the timing of the peak in chlorophyll a at the outlet. PLFA represents the FI of the Pony Lake fulvic acid, a microbial end member, and SRFA represents the FI of the Suwannee River fulvic acid, a terrestrial end member. (Adapted from MiUer et al., 2009.)...

Figure 9.14. Relationship between McKnight et al. (2001) fluorescence index (FI) (a, b) and freshness index (jS/0 ) (c, d) to characteristics of land cover and nutrients for 34 watersheds. FI correlated positively with % of continuous cropland in the riparian zone (a) and negatively with % wetland in the riparian zone (square root transformed) (b) whereas (j8/a) correlated positively with both % of continuous cropland (c) and log total dissolved nitrogen (TDN) (d). These results support the ability of fluorescence indices to respond to changes in catchment and stream characteristics. (Adapted from Wilson and Xenopoulos, 2009.)...

Figure 9.15. Relationship between the McKnight et al. (2001) fluorescence index (FI) and the C/N ratio for DOM samples from a variety of freshwater and marine sites studied in the LTER network and elsewhere. Higher FI DOM, attributed to predominately microbial precursor material, generally had a lower C/N ratio, whereas lower FI DOM, attributed as predominately terrestrial precursor material, had a higher C/N. This also shows the value of using proper measurement and correction techniques so results and indices can be compared between labs and sites. (Adapted from Jaffe et al., 2008.)...

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