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At least 19 recordsLinked to original sources
PubMed1977

Formaldehyde-induced fluorescence in the telencephalon and diencephalon of the eel (Anguilla anguilla l.). A fluorescence-microscopic and microspectrofluorometric investigation with special reference to the innervation of the pituitary.

In the telencephalon and diencephalon of the eel (Anguilla anguilla L.) formaldehyde-induced fluorescence was studied microscopically and microfluorometrically with special emphasis on the innervation of the pituitary. In the telencephalon fluorescent fibers contained predominantly noradrenaline fluorophores. Fluorescent nuclei could not be established. In the diencephalon fluorescent perikarya were found in: (1) the paraventricular organ (PVO), possessing either dopamine or, to a lesser extent, serotonin fluorophores; (2) the PVO-accompanying group, exhibiting spectral data resembling those of noradrenaline fluorophores; (3) the nucleus hypothalami anterior (NHA), a small paired group of catecholamine-containing cells posterior to the commissura transversa.--The nucleus lobi inferioris exhibited a high density of delicate, most probably dopamine-containing terminals, while fibers surrounding this nucleus contained noradrenaline fluorophores. A high density of fluorescent terminals containing dopamine and/or noradrenaline was found in the habenular complex. Fluorescent terminals in the pituitary contained fluorophores resembling either dopamine or noradrenaline. Fluorescent tracts entered the pituitary from different directions. A rostral, unpaired tract enters the neurointermediate lobe, as also verified experimentally. The rostral pars distalis receives two paired tracts, one from a rostral and one from a dorsal direction. The proximal pars distalis also receives two paired tracts, one from a dorsal and one from a posterior direction.

Anguilla↗
PubMed1976

Fluorescence and the structure of proteins. XXI. Fluorescence of aminotyrosyl residues in peptides and helical proteins.

1. Five peptides containing tyrosine were converted to the 3-aminotyrosyl peptides by nitration with tetranitromethane and subseuqent reduction of the nitro groups to amino groups. The fluorescence of these aminotyrosyl residues was found to be quite similar to that of 3-aminotyrosine and it is concluded that the fluorescence is not sensitive to incorporation of the amino acid into the peptide chain. 2. Fluorescence of 3-aminotyrosine derivatives was sensitive, however, to the nature of the solvent; as the dielectric constant decreased, fluorescence was enhanced ten fold and the emission maximum shifted from the 350-370 nm value in aqueous solution to 320 nm. It is predicted that similar differences might be expected for exposed and buried aminotyrosyl residues in a protein. 3. Exposed tyrosyl residues on the helical protein tropomyosin and a helical segment of paramyosin were aminated in part (39% and 34% of the total tyrosyl residues, respectively). The fluorescence of the aminated tyrosyl residues on these proteins was similar to that of the aminotyrosyl peptides in an aqueous medium. Although the fluorescence efficiency of an aminotyrosyl residue was much lower than that of a tyrosyl residue, it was easy to distinguish the fluorescence of the aminotyrosyl residues (350-355 nm) on the protein from that arising from unmodified tyrosyl residues (305 nm).

Binding Sites↗
PubMed1976

Fluorescence-detected magnetic circular dichroism of fluorescent and nonfluorescent molecules.

We have modified a spectrometer for the measurement of fluorescence-detected magnetic (and natural) circular dichroism (FDMCD). The instrument can be operated either in a direct mode in which the average and polarization-induced differential fluorescent intensities are recorded separately or in a mode which records their ratio. We have measured the FDMCD of tryptophan, which is itself fluorescent. With the aid of an added fluorescent molecule we also measured the FDMCD of Fe(III) cytochrome c, which is nonfluorescent. In both cases, the FDMCD agreed with the conventional transmission-detected magnetic circular dichroism within experimental uncertainty. The FDMCD of both fluorescent and nonfluorescent molecules is potentially a useful technique for investigating optically dense materials and biological molecules in their native environments and systems in which there is inter- or intramolecular energy transfer.

Circular Dichroism↗
PubMedDate not supplied

[Relation between fluorescence and circular dichroism of the complex of the fluorescence probe 4-dimethylaminochalcone with serum albumin].

The fluorescence probe(4-dimethylaminochalcone; DMH) was noncovalently linked to human serum albumin (HSA). The variation of pH was due to serum albumin structural changes, which was determined in terms of DMH and HSA fluorescence and CD spectra. Considerable changes of fluorescence and CD spectra were observed at pH 8 and 10, where there is ionization of two more recently titrated tyrosin residues. It is assumed that these two tyrosine residues are in binding region and quench the fluorescence of DMH between pH 4 to 8. Quenching disappears if these residues are ionized (pH greater than 8) or if the protein undergoes the N -F transition (pH less than 4).

Chalcone↗
PubMed1979

Fluorescent colloidal gold: a cytochemical marker for fluorescent and electron microscopy.

The gold method was further developed for fluorescent microscopy. Gold granules (12 nm in size) were labelled with rhodamine conjugates of Concanavalin A and avidin. The fluorescent markers were used to mark cell wall mannan on the yeast Saccharomyces cerevisiae either by the one-step, or by the two-step method via a biotinyl derivative of ConA. By fluorescence or transmission electron microscopy, the two-step method was found to achieve a higher density of marking.

Avidin↗
PubMed1978

Fluorescent labeling of hormone receptors in viable cells: preparation and properties of highly fluorescent derivatives of epidermal growth factor and insulin.

Highly fluorescent analogs of insulin and epidermal growth factor were prepared by the covalent attachment of these peptides to alpha-lactalbumin molecules that were highly substituted (i.e., seven to one) with rhodamine molecules. The alpha-lactalbumin was specifically linked to the lysine residue of insulin or to the alpha-amino group of epidermal growth factor. The insulin derivative retained 1.15% of its potency in stimulating glucose oxidation in fat cells but retained about 8.3% of its binding affinity toward receptors. The epidermal growth factor derivative was completely active in binding to fibroblast receptors and 40% as potent as the native hormone in stimulating DNA synthesis. These highly fluorescent derivatives were suitable for the specific visual labeling of receptor sites in viable cells and for measuring the lateral mobilities of the receptor-hormone complexes by fluorescent photobleaching recovery techniques. By these methods it was shown that the hormone-receptor complexes can move laterally in the plane of the plasma membrane with a diffusion coefficient of (3-5) X 10(-10) cm2/sec.

Adipose Tissue↗
PubMed1978

Use of isolated nuclei in the indirect fluorescent-antibody test for human cytomegalovirus infection: comparison with microneutralization, anticomplement, and conventional indirect fluorescent-antibody assays.

Use of an antigen consisting of purified isolated nuclei from a mixture of human cytomegalovirus-infected and uninfected fibroblasts in a 2:1 ratio is a simple and reliable method for eliminating nonspecific fluorescence associated with the presence of Fc-immunoglobulin G receptors in the cytoplasm of infected cells. The specificity obtained with this antigen on 100 normal human sera was 99, 100, and 98% when compared with microneutralization, anticomplement immunofluorescence, and conventional indirect fluorescent-antibody assays, respectively. Also, 95% of the antibody titers obtained with the nuclear antigen had a perfect correlation with or were within a fourfold-dilution difference of the antibody levels obtained by anticomplement immunofluorescence and the conventional indirect fluorescent-antibody test.

Antibodies, Viral↗
PubMed1976

Extrinsic signals for monitoring the association reaction of proteins as introduced by fluorescent and non-fluorescent labels.

Two known dansyl labels (I, II) and 5-[2-(iodoacetamido)ethylamino]-1-naphthalene-sulfonic acid (III) and three new azo-dyes (IV - VI) were covalently attached to alpha-chymotrypsin and to basic pancreatic trypsin inhibitor by four different reactive groups. In order to protect the contact region of the proteins the complex of the two proteins was labeled. Advantage was taken of the fact that a group which is buried in the complex reacts about (see article) times slower than a group which is always exposed (K = dissociation equilibrium constant, [C] = concentration of the complex). The complex was dissociated at pH 3 and the labeled proteins were isolated by column chromatography. They were fully active. The dansyl label was immobilized when introduced by dansyl chloride but highly mobile when attached via the longer imidoester group (II). Changes of absorption and of fluorescence which occur when differently labeled reaction partners recombine were studied. Changes in absorption (up to 18%) were mainly due to interactions of the label of one protein with the other protein. Fluorescence changes of up to 480% could be obtained. They were interpreted in terms of a Förster type energy transfer between donor and acceptor labels and changes of absorption and quantum yield due to interactions of the labels with the proteins. The kinetic constants of complex formation are not seriously altered by the labels (Bösterling, B & Engel, J. (1976) this J. 357, 1297-1307, succeeding). It is concluded that the labeling technique may be of general value for kinetic and equilibrium studies of protein associations.

Affinity Labels↗
PubMed1978

Changes in fluorescence of 8-anilino-1-naphthalene sulfonate after bacteriophage T5 infection of Escherichia coli. Initial fluorescence rise coincides with onset of rubidium efflux.

Escherichia coli cells pre-loaded with 86Rb+ begin to lose 86Rb+ immediately after phage T5 addition. The loss proceeds with negative-exponential (first-order) kinetics for up to approximately 15 min after phage addition. The constant which characterizes the rate of loss increases with increasing numbers of infecting phage per cell. It is known that anaerobic, fermenting cells of E. coli show a two-step increase in 8-anilino-1-naphthalene sulfonate (ANS) fluorescence upon infection with bacteriophage T5; the first rise begins immediately upon phage addition, the second 6 min later. The onset of 86Rb+ release, therefore, is correlated with the first fluorescence rise with respect to timing and response to the multiplicity of infection.

Aerobiosis↗
PubMed1977

Comparison of rabies humoral antibody titers in rabbits and humans by indirect radioimmunoassay, rapid-fluorescent-focus-inhibition technique, and indirect fluorescent-antibody assay.

Rabies humoral antibodies were induced in eight New Zealand rabbits by a single intramuscular injection of inactivated suckling mouse brain rabies vaccine. The primary response to immunization was measured in blood samples taken at selected intervals for 6 months. The anamnestic response was measured in blood samples obtained 2 weeks after the rabbits received a booster immunization. The humoral antibody concentrations were measured by the rapid-fluorescent-focus-inhibition technique (RFFIT), indirect fluorescent-antibody assay (IFA), and indirect radioimmunoassay (RIA). The maximal neutralizing antibody titers as measured by RFFIT were attained by the 4th week and persisted into the 24th week. After booster immunization the antibody response was almost 10-fold higher than the highest level attained in the primary response. The antibody levels as measured by IFA and RIA were similar, but the titers as measured by either procedure were almost 10-fold lower than those determined by RFFIT. After booster immunizations the antibody levels, as measured by IFA and RIA, were three- and sixfold higher, respectively, than the maximal levels attained in the primary response. Twenty-two human serum specimens were tested by the same serological procedures, with disparate results. Both RIA and RFFIT effectively differentiated antirabies-positive sera from antirabies-negative sera.

Animals↗
PubMed1976

Influence of various fluorescent and non-fluorescent labels on the kinetics of the complex formation of alpha-chymotrypsin with basic pancreatic trypsin inhibitor (Kunitz).

The association of alpha-chymotrypsin with basic pancreatic trypsin inhibitor was studied using extrinsic signals produced by fluorescent and nonfluorescent labels. The reactive dyes were covalently bound to the proteins in the complexed state, in which the binding region was protected. The signals were sufficiently large to measure the complex formation at protein concentrations of 10(-9)M by fluorescence and down to 10(-6)M by absorption. Therefore, the association and dissociation could be followed over a broad range of concentration. Good correspondence was observed between data which were obtained with different labels and with published values for the unlabeled proteins. Existing differences could be explained by different buffer conditions used by the different authors. Also the pH dependence of the dissociation rate constants was essentially unaltered by the introduction of the labels. The large signals allowed a direct measurement of the equilibrium constants of dissociation, even at high pH, at which they are in the range of 10(-8)M. The experimentally determined binding constants were in agreement with those calculated from the rate constants. The temperature dependence of the binding constants revealed a small positive and pH-dependent enthalpy change [deltaHo = 4.0 kcal/mol (16.7 kJ) at H 7.0[. The results prove that the labeling can be performed in such a way that the equilibrium and kinetic parameters of the system studied are not significantly influenced.

Affinity Labels↗
PubMed1978

[The differentiation of clostridial microcultures on nuclepore-filters by fluorescent antibodies as a rapid screening test for spores. II. Application of fluorescent antibodies (author's transl)].

The study deals with the question of whether a combination of microcolony-cultivation on polycarbonate-membrane-filters with the fluorescent-antibody-method will lead to a rapid-diagnosis method for clostridial-spores. Formaldehyd-inactivated vegetative cells of eight different clostridial-strains (Table 1) were used for the immunisation of rabbits according to the method published by Böhm and Strauch (5). The results of the immunisation procedure, developed for aerobic-sporeformers, showed, that satisfactory results could not be obtained in all cases (Table 2). The eight conjugates were tested against microcolonies of 32 strains of different clostridial-species on membrane-filters, produced by the technique described in the first communication. The results showed (Table 4) that differentiation was always possible when homologous antisera were used. In most cases, in order to differentiate between the various species, conjugates of several serotypes had to be employed together. However due to their uniform antigenic nature, Cl. feseri and Cl. tetani could both be identified by using one strain for each to immunize. With clostridial-spores the species could be identified within a period of 6 to 12 hours by using the membrane-filter-fluorescent-antibody technique.

Antibodies, Bacterial↗
PubMed1977

Fluorescent probes for antibody active sites. II. Further studies on two groups of anti-MANS antibodies with significantly different effects on MANSamide fluorescence produced by a single rabbit.

As described previously, a single rabbit (No. 13) produced two groups of anti-MANS antibodies with significantly different effects on MANSamide fluorescence. These groups, anti-MANS antibody (415 nm) and anti-MANS antibody (465 nm), had emission maxima at 415 nm and 465 nm, respectively. This paper deals with the immunochemical properties of the two groups of antibodies (1) The results of fluorometric titration of these groups with MANSamide indicated that anti-MANS antibody (465 nm) had a higher affinity for MANSamide than did anti-MANS antibody (415 nm). (2) More than 70% of anti-MANS antibody (415 nm) was adsorbed on Sepharose covalently coupled with bovine serum albumin, which was used as a carrier during immunization, while a hlaf of anti-MANS antibody (465 nm) was adsorbed. (3) Only one of the groups, anti-MANS antibody (465 nm), had precipitating activity toward MANS-rabbit serum albumin used as a test antigen.

Anilino Naphthalenesulfonates↗
PubMed1976

Effects of ATP and magnesium ions on the fluorescence of harmala alkaloids. Restrictions for the use of harmala alkaloids as fluorescent probes for (Na+ + K+)-ATPase.

1. Harmine and harmaline were investigated as potentially useful fluorescent inhibitors of (Na+ + K+) activated ATPase. 29 From spectroscopic measurements both compounds were shown to form 1 : 1 complexes with ATP, the dissociation constants being 0.65 mM and 1.83 mM for harmine and harmaline respectively. Addition of Mg2+ and enzyme further affected these equilibria. 3. Although it was possible to demonstrate a competitive effect of harmine at the sodium-loading site of the enzyme, other inhibitory effects, including inhibitions of ouabain binding and the ouabain-insensitive ATPase were found. 4. It was concluded that the harmala alkaloids can inhibit (Na+ + K+)-activated ATPase in a complex way involving both Na- and ATP-binding sites. This severely limits their usefulness as spectroscopic probes.

Adenosine Triphosphatases↗
PubMed1979

Separation of mouse T cell subsets by a fluorescent activated cell sorter using fluorescence-labeled peanut agglutinin.

Nylon non-adherent spleen T cells obtained from concanavalin A-injected mice were labeled with fluorescein-labeled peanut agglutinin and separated into peanut agglutinin-positive (PNA+) cells and peanut agglutinin-negative (PNA-) cells by a fluorescent activated cell sorter. PNA+ cells were found to exert marked suppressive effect on primary anti-sheep red blood cells antibody response, but PNA- cells did not affect the antibody response. From these results and from the sugar-binding specificity of PNA, suppressor T cells are supposed to possess abundant galactosyl residues exposed on the cell surface, which are not masked by sialyl residues.

Animals↗