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Results for “Rhodamines”

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PubMed1975

An approach to quantitation in rhodamine isothiocyanate labeling.

A survey of commercially available TMRI and RBI products revealed that many are of unsatisfactory quality. Optimum dye/IgG ratios were obtained in conjugates with TMRI of about 65% purity by labeling them with reaction mixture ratios of 10 and 20 mug dye/mg IgG. Optimum labeling with RBI of comparable purity required reaction mixture ratios of at least 20 mug dye/mg IgG. Although specific storage stability studies of TMRI or RBI products were not performed, one TMRI product underwent appreciable degradation during a 2-year period of storage in a desiccator over Drierite. The importance of evaluating the protein labeling capacity of TMRI or RBI products before making immune conjugate preparations is evident.

Animals↗
PubMed1979

Rhodamine as a fluorescent probe of lymphocyte activation.

Fresh rat and mouse lymphoid cells have been labelled by stable linkage with tetramethylrhodamine isothiocyanate (TMRITC). A change in intensity, either an increase or decrease of the fluorescent emission of the cells, detected by microfluorimetry, was induced by mitogen stimulation or the mixed lymphocyte reaction. The change in fluorescence was observed within 3 h of mitogen stimulation and within 0.5 h in the mixed lymphocyte test. These early cellular responses were detectable consistently whether the labelling was done before or after mitogen stimulation; post-labelling only was studied in the mixed lymphocyte reaction. The method should provide a time-saving practical procedure for early detection of the lymphoid cell responses and would readily lend itself to flow cytofluorimetry for possible routine diagnostic use.

Animals↗
PubMed1978

Rhodamine B.

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Animals↗
PubMed1978

Rhodamine 6G.

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Animals↗
PubMedDate not supplied

[Random immunoglobulin. I. Use of chaotropicions and fluorescence quenching for quantitating the non-specific adsorption in the interaction of human IgG with rhodamine B].

It is shown that, when excited in the visible range, fluorescence of the dye may be either quenched or enhanced, from its initial value Fo, by addition of increasing "normal" immunoglobulin (IgGH7 S), depending if the solution is "non-chaotropic " (NaF 0,1 M) or "chaotropic" KI 1 M). Let F be the fluorescence obtained at concentration P in protein, then the plot of the quantity P.F/(FO-F)against the quantity P.F/(FO-F) gives a straight line; the zero ordinate of this is the inverse of the non-specific interaction equilibrium constant. Quenching of fluorescence by increase of temperature, and by increase of concentration of salt (KI) are also quantitatively dealed upon in order to testify that this non-specific interaction is of the "adsorption" type. Concentration of dye is 10-6M; concentration of protein is varied from 0,05 % to 0,5 %.

Adsorption↗
PubMed1976

Conjugation methods in immunofluorescence.

We have described methods of labeling antibody preparations with FITC, TMRI, and RBI. The degree of labeling with FITC can be precisely controlled by using well-defined conjugation procedures and FITC of a known degree of purity. Our experience shows that relatively high F/P ratios of the order of 20 to 25 mug/mg are desirable for antibacterial conjugates. Many commercial preparations of rhodamine isothiocyanate are of very poor quality and are unsatisfactory for use in conjugate preparation. Therefore, one should analyze the rhodamine isothiocyanate product before preparing immune conjugates. Our experience indicates that very satisfactory conjugates of immune IgG or pure antibody can be prepared with TMRI of about 60% purity by using a dye-protein ratio of 20 mug/mg. The optimal dye-IgG ratio for labeling with RBI appears to be about two times that for labeling with TMRI because of the lower specific absorbance and fluorescence emission of RBI. Rhodamine conjugates may be preferred to FITC conjugates in certain situations where tissue autofluorescence interferes with the observation of the yellow-green emission of FITC. Furthermore, mixed rhodamine and FITC conjugates of different specificity can be used to great advantage in double-staining techniques that allow simultaneous screening for two antigenically different organisms on a single microscope slide.

Fluoresceins↗
PubMed1977

Localization of serum-derived alpha 2 macroglobulin in cultured cells and decrease after Moloney sarcoma virus transformation.

NRK cells and many other cultured fibroblasts were found to contain the protease inhibitor, alpha 2 macroglobulin (alpha 2M). This alpha 2M is present as a result of uptake of alpha 2M from the calf serum in the culture medium. Some of this alpha 2M is released back into the medium. In radiolabeling experiments with 14C-amino acids, no radioactivity was detected in intracellular or extracellular alpha 2M. Fluorescence microscopy of fixed cells using rhodamine-labeled antibodies indicated that alpha 2M is present in vesicular organelles different from primary lysosomes. Fluorescence microscopy of living cells shows that rhodamine-labeled alpha 2M (rhodamine-alpha 2M) is taken up into similar structures. Of the many cell lines examined, Moloney sarcoma virus-transformed cells had the lowest amounts of alpha 2M. Some of the effects of serum on the behavior of cultured cells could be a consequence of inhibition of cellular proteases by alpha 2M.

Animals↗
PubMed1979

Fluctuations in polarized fluorescence: evidence that muscle cross bridges rotate repetitively during contraction.

Particular thiols of the myosin subfragment 1 moieties of single glycerinated muscle fibers are covalently labeled with rhodamine. By using appropriate solutions such fibers can be relaxed, be in rigor, or develop active isometric tension. The rhodamine is excited by polarized 514.5-nm laser light; the greater than 580-nm fluorescence is resolved into orthogonal components and the intensity of each is measured by a computer-interfaced photon counting system. Fluctuations over-and-above noise appear in steady-state activity but not in relaxation or rigor and not when the fluorophore is actin-attached instead of myosin-attached. Fluctuations also appear in ratios of polarized intensities--quantities sensitive to fluorophore attitude but not to fluorophore number. The fluctuations are dominated by low (approximately 2 Hz) frequencies similar to separately measured ATPase frequencies. The fluctuations are ascribed to repetitive motion of the cross bridges to which the rhodamine is attached.

Actins↗
PubMed1979

Proximity of lectin receptors on the cell surface measured by fluorescence energy transfer in a flow system.

Molecules of the lectin concanavalin A have been labeled separately with the fluorescein and rhodamine chromophores and jointly bound to the surface of transformed Friend erythroleukemia cells. The two dyes constitute an ideal donor-acceptor pair for fluorescence resonance energy transfer thereby permitting the determination of the proximity relationships between bound ligand molecules and the corresponding surface receptors. The transfer efficiency at saturation (about 57%) was measured in a multiparameter flow system using laser excitation at 488 nm and detection of fluorescein and rhodamine emission intensities as well as the emission anisotropy of the rhodamine fluorescence for each cell. The degree of energy transfer was estimated from the quenching of donor emission, the sensitization of acceptor emission, and the depolarization of acceptor fluorescence. The system has been modeled according to a formalism developed by Gennis and Cantor (Biochemistry 11: 2509, 1972). We estimate the separation between the surfaces of bound lectin molecules at saturation to be 0-40 A, a range possibly characteristic for micropatches induced by ligand binding.

Animals↗
PubMed1977

Incorporation characteristics of uracil, uridine, and orotic acid into ribonucleic acid of neoplastic cells.

Incorporation of uracil and uridine into ribonucleic acid (RNA) was compared among the ascitic and solid forms of Ehrlich mouse tumor, Morris hepatoma, Rhodamine sarcoma, gastric cancer and ulcer from human patients, and several normal rat tissues. Of these cells tested, the cells of Ehrlich ascites and solid tumors, human gastric cancer and ulcer, and certain tissues of a normal rat showed a considerably high activity. Furthermore, Ehrlich ascites tumor cells indicating a high incorporation activity was also high in activities of both phosphorylase and kinase for uridine, while Rhodamine sarcoma as a representative having a low incorporation activity was considerably low in these two enzymic activities. RNA synthesis from uridine phosphates by Rhodamine sarcoma was maintained to a fairly high extent contrary to its low activities of the phosphorylase and the kinase. Consequently, the low utilization of uracil and uridine by certain tumors was suggested to be due to the extremely low activities of both enzymes.

Adult↗
PubMed2026

HoT auto-blinking probes enable real-time, super-resolution chromatin imaging in live cells and tissues.

Single-molecule localization microscopy (SMLM) enables visualization of chromatin architecture at nanoscale resolution. However, high-performance DNA probes suitable for SMLM in both live cells and tissues remain limited. We developed Hoechst-6-Carboxytetramethylrhodamine (6-TAMRA) derivative (HoT) probes-rhodamine-based derivatives conjugated to a Hoechst moiety-through structural fine-tuning of rhodamine spirocyclization. HoTs are self-assembling, auto-blinking probes with excellent photostability and high temporal resolution. They permeate live cells, enabling long-term, real-time nanoscopic chromatin imaging in live and fixed cells and in tissue sections. In live cells, we identified nanoscale features in the 3D organization of chromatin and quantified DNA fiber kinetics at high resolution. We quantified DNA compaction in single cells within retinal and colon cancer sections. OligoSTORM (stochastic optical reconstruction microscopy)-labeled gene loci can be visualized and measured within their HoT-labeled chromatin footprints. Our work provides powerful tools for investigating chromatin structure and functions in living cells and tissues, with applications ranging from cancer diagnosis to retinal regeneration.

Chromatin↗
PubMed1979

Serological differentiation between infected and vaccinated cattle by visual and quantitative immunofluorescence using Brucella abortus antigen coupled sepharose beads.

The ability to differentiate cattle infected with brucellosis from animals vaccinated against the disease is of considerable economic advantage in countries adopting eradication schemes. Current serological tests such as bacterial tube agglutination do not readily distinguish cattle in this way. An immunofluorescent procedure was investigated in an attempt to overcome this problem. Antigenic extract of brucella abortus strain 544/W were coupled to sodium metaperiodate oxidised Sepharose CL4B beads. Following coupling, the beads were chemically reduced or blocked with rhodamine labelled BSA prior to reduction. Characterised bovine serum samples were tested by indirect immunofluorescence on both types of bead and by standard bacterial tube agglutination. Serological discrimination between infected and vaccinated cattle was achieved by fluorescence quantitation using unblocked beads and by visual determination of colour using rhodamine-albumin blocked beads. Bacterial tube agglutination failed to distinguish between the two groups of sera.

Agglutination Tests↗