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At least 937 records · Page 52Linked to original sources
PubMed2002

Fluorescent signaling based on control of excited state dynamics. Biarylacetylene fluorescent chemosensors.

We have previously reported that metal ion binding could restrict the excited state rotation of a biaryl chromophore, suppressing intersystem crossing and leading to increased emission. We have now applied the restriction of excited state dynamics to suppression of the other fundamental nonradiative decay pathway, internal conversion, in biarylacetylenes. This indicates that both nonradiative decay pathways are subject to conformational control, and that this signaling pathway should be generally accessible in simple flexible fluorophores.

Journal Article↗
PubMed2002

Stable expression of Anthozoa fluorescent proteins in mammalian cells.

BACKGROUND: Fluorescent proteins have become invaluable reporters in many areas of cellular and developmental biology. An enhanced version of the Aequorea victoria green fluorescent protein (AvEGFP) is the most widely used fluorescent protein. For a variety of reasons, it is useful to have alternative fluorescent proteins to AvEGFP. METHODS: The cDNA sequences for enhanced variants of the Anemonia cyan fluorescent protein (AmCyan1), as well as the Zoanthus green (ZsGreen1) and yellow (ZsYellow1) fluorescent proteins, were cloned downstream of a constitutive cytomegalovirus (CMV) promoter within a retroviral expression vector. NIH3T3, HEK293, SW620, and WM35 cells were transduced with recombinant retroviruses at a low multiplicity of infection (MOI) to bias for single-copy integration. Both unselected and stably selected cells transduced with the retroviral expression constructs were characterized. Expression of each fluorescent protein in cells was detected using flow cytometry and fluorescence microscopy with filter sets typically used for AvEGFP/fluorescein isothiocyanate (FITC) detection and was compared with the expression of AvEGFP. In addition, a fluorescence plate reader with several excitation and emission filter sets was used for detection. RESULTS: Expression of each protein was observable by fluorescence microscopy. Under given conditions of flow cytometry, the ZsGreen1 mean fluorescence was approximately 3-fold, 10-fold, and 50-fold greater than that of AvEGFP, ZsYellow1, and AmCyan1, respectively. AmCyan1, ZsGreen1, and AvEGFP were detected by a fluorescence plate reader. CONCLUSION: We determined that fluorescent proteins from Anthozoa species are detectable using a standard flow cytometer and fluorescence microscope. All of the mammalian cell lines tested expressed detectable levels of fluorescent proteins from stable integrated provirus. In cell lines where the AvEGFP protein is toxic or poorly expressed, these Anthozoa fluorescent proteins may serve as alternative fluorescent reporters.

3T3 Cells↗
PubMed2002

Fluorescence properties of some farm wastes: implications for water quality monitoring.

Some farm wastes have been analysed for their fluorescence properties using fluorescence excitation-matrix (EEM) spectroscopy. Farm wastes investigated were silage liquor, pig and cattle slurry, and sheep barn waste. All farm wastes exhibited high intensities of fluorescence that can be attributed to the protein tryptophan. Silage liquor was characterised by a very high fluorescence intensity and an initial tryptophan: fulvic-like fluorescence intensity ratio of >20. Cattle and pig slurries exhibited a lower tryptophan : fulvic-like fluorescence intensity ratio (approximately 2-5) and lower tryptophan fluorescence intensity, and tyrosine fluorescence was also observed. Sheep barn wastes had the lowest tryptophan: fulvic-like fluorescence intensity ratios (approximately 0.5-4.0). Farm waste samples were reanalysed under controlled temperature conditions over a period of 50 days after sampling, to investigate the stability of their fluorescence properties. For silage liquor. tryptophan: fulvic-like fluorescence intensity ratios were observed to decrease with time, and were associated with a decrease in tryptophan fluorescence intensity, suggestive of clostridia breakdown of protein. For slurry samples. tryptophan: fulvic-like fluorescence intensity exhibited a more variable time-evolution, and tryptophan fluorescence intensity increased through time; the more complex fluorescence signal is due to the relatively heterogeneous nature of the slurry. Sheep barn waste samples exhibited more stable tryptophan: fulvic-like fluorescence intensity ratio and tryptophan intensities, suggesting these samples were more stable due to their greater age and decomposition. The ratios of tryptophan: fulvic-like fluorescence intensity observed from the farm wastes investigated are significantly higher than those observed in the majority of river waters, suggesting that farm waste pollution events could leave a signature in river waters due to their distinctively high protein fluorescence intensity.

Agriculture↗