Labeling with Lucifer Yellow

The octopamine content per cell is calculated by subtracting the background level detected in a matched blank tube from the level detected in the sample. The resulting value is then divided by the number of cells in the sample The mean octopamine content for these four samples is 27.07 pg/cell (0 143 pmol/cell). Dye marked cells were labeled with Lucifer yellow ND not detectable... 

Tang, L. X. Rowell, F. J. Flow injection fluorescence measurement of collagenase using a mini-bioreactor with immobilized collagen labeled with Lucifer Yellow. Anal Proc. 1995, 32, 255-256. 

Spiegel, S., Wilchek, M., and Fishman, P.H. (1983) Fluorescent labeling of cell surface glycoconjugates with Lucifer Yellow CH. Biochem. Biophys. Res. Comm. 112, 872-877. 

Quantification of cell-to-cell communication. Flow cytometry meikes it easy to quantify cell-to-cell communication. As an example work of Kavanagh may be cited. Cells are scrape-loaded with Lucifer yellow with or without rhodamine labelled dextran. The transfer of the two dyes between donor and recipient cells can be studied easily using two colour fluorescence flow cytometry. 

One Lucifer Yellow derivative is available for labeling sulfhydryl-containing molecules. Lucifer Yellow iodoacetamide is a 4-ethyliodoacetamide derivative of the basic disulfonate aminonaph-thalimide fluorophore structure (Invitrogen). The iodoacetyl groups react with —SH groups in proteins and other molecules to form stable thioether linkages (Figure 9.42). 

Lucifer Yellow probes are water-soluble to at least 1.5%. The absorbance maximum of the derivatives occurs at about 426—428 nm with an emission peak at about 530—535 nm, in the yellow region of the spectrum. The quantum yield of Lucifer dyes is about 0.25. The good intensity of luminosity from these dyes makes possible detection of small quantities of labeled molecules intracellularly. The fluorescent conjugates are readily visible in living cells at concentrations that are nontoxic to cell viability. The low molecular weight and water solubility of these dyes allow passage of labeled compounds from one cell to another, potentially revealing molecular relationships... 

The decay time of the fluorophor used as label should be longer than the rotational time of the hapten but shorter than the rotational time of the complex formed. Fluorescein, which has a fluorescence lifetime of 4.5 ns, or rhodamine are the most frequently used fluorophors. For larger antigens, fluorophors with somewhat longer decay times such as Lucifer yellow, dansyl, and umbelliferone derivatives have been tested. In a typical competitive format, the degree of polarization is inversely proportional to the concentration of the analyte. 

In most experimental situations, a choice of fluorochromes is available. Where two fluorochromes are used in the same specimen, it is important that their fluorescence signals be clearly distinguished (for example, different populations of dye-labeled axons or different immunolabels). It is important to compare the specifications of the excitation and emission filters with the absorption and emission spectra of the fluorochromes chosen. Other factors that should be taken into account are the brightness and photostability of a particular fluorochrome. Some fluorescent dyes survive fixation better than others. For example, for intracellular dye injection, the highly fluorescent 5,6-carboxyfluorescein cannot be fixed, whereas the relatively less bright lucifer yellow can be cross-linked by paraformaldehyde fixation. 

The carefully controlled treatment of PCL and polylactide microspheres with KOH solution allows particles with interfa-dal layer rich in carboxyl and hydroxyl groups to be obtained. These groups could be used for binding fluorescent labels, for example, 6-aminoquinoline and Lucifer yellow. In biological and medical studies, the fluorescent particles are often used for monitoring an uptake of particulate material by cells and for its visualization in various intracellular compartments. 

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