'Chemotactic excitation responses to caged ligand photorelease of rapidly swimming bacteria that reverse (Vibrio alginolyticus) or tumble (Escherichia coli and Salmonella typhimurium) have been measured by computer. Mutants were used to assess the effects of abnormal motility behavior upon signal processing times and test feasibility of kinetic analyses of the ... More
Spectral and photophysical studies of benzo[c]xanthene dyes: dual emission pH sensors.
AuthorsWhitaker JE, Haugland RP, Prendergast FG
JournalAnal Biochem
PubMed ID1862936
'A series of fluorescent, long-wavelength, benzo[c]-xanthene dyes has been characterized for pH measurement in both excitation and emission ratio applications. The two general classes of these indicators are seminaphthofluoresceins (SNAFLs) and seminaphthorhodafluors (SNARFs) which are substituted at the 10-position with oxygen or nitrogen, respectively. These probes show separate emissions from ... More
Characterization of dual-wavelength seminaphthofluorescein and seminapthorhodafluor dyes for pH sensing under high hydrostatic pressures.
AuthorsSalerno M, Ajimo JJ, Dudley JA, Binzel K, Urayama P
JournalAnal Biochem
PubMed ID17274941
'Hydrostatic pressure is an important physical parameter in biology, with pressures in the few-hundred-atm range having significant effects on cellular morphology, metabolism, and viability. To ensure valid results when studying pressure effects using fluorescence spectroscopy and imaging methods, metabolic probes need to be characterized for high-pressure use. Of interest is ... More
Using LysoSensor Yellow/Blue DND-160 to sense acidic pH under high hydrostatic pressures.
AuthorsDePedro HM, Urayama P,
JournalAnal Biochem
PubMed ID18976626
LysoSensor Yellow/Blue DND-160, a dual-wavelength fluorophore commonly used for sensing pH in acidic organelles, possesses solvatochromic behavior believed to originate from an intramolecular charge transfer (ICT). Given this, we investigated whether DND-160 can be used for acidic pH sensing under hydrostatic pressures up to 510 atm, a range suitable for ... More
Characterization of probe binding and comparison of its influence on fluorescence lifetime of two pH-sensitive benzo[c]xanthene dyes using intensity-modulated multiple-wavelength scanning technique.
AuthorsAndersson RM, Carlsson K, Liljeborg A, Brismar H
JournalAnal Biochem
PubMed ID10929815
Quantitative pH imaging using the carboxy seminaphthofluorescein dyes SNAFL-1 and SNAFL-2 can be performed by measurement of intensity ratios or fluorescence lifetimes. However, there is a controversy as to whether the latter method has the practical advantage of a straightforward pH calibration in buffers compared to a cumbersome and time-consuming ... More
Fluorescence spectroscopy of pH in vivo using a dual-emission fluorophore (C-SNAFL-1).
AuthorsMordon S, Devoisselle JM, Soulié S
JournalJ Photochem Photobiol B
PubMed ID7791002
The aim of this study was to evaluate a dual-emission fluorophore (C-SNAFL-1: 5'(and 6')-carboxyseminaphthofluorescein) for in vivo pH monitoring, using one excitation wavelength and two emissions. P388-tumour-bearing CDF mice were injected intravenously with C-SNAFL-1. Glucose was administered simultaneously to lower the tumour pH. Under our experimental conditions, tissue autofluorescence was ... More
Optical measurements of pH using fluorescence lifetimes and phase-modulation fluorometry.
AuthorsSzmacinski H, Lakowicz JR
JournalAnal Chem
PubMed ID8368522
We measured the pH-dependent fluorescence decay times of the seminaphthofluoresceins (SNA-FL), seminaphthorhodafluors (SNARF), and BCE-CF using phase-modulation fluorometry. The phase and modulation values were found to be strongly pH-dependent in the physiological pH range, over the easily accessible range of light modulation frequencies from 10 to 300 MHz, making these ... More
Hydrolysis of monodisperse phosphatidylcholines by phospholipase A2 occurs on vessel walls and air bubbles.
AuthorsYu BZ, Berg OG, Jain MK
JournalBiochemistry
PubMed ID10441140
Hydrolysis of monodisperse short chain phosphatidylcholines, far below their critical micelle concentration, by phospholipase A2 (PLA2) and other interfacial enzymes is characterized. Results show that virtually all the observed hydrolysis by pancreatic and human inflammatory PLA2 occurs on surfaces of the reaction vessel or air bubbles. Conditions to eliminate such ... More