Visualization of Protein‐Specific Glycosylation inside Living Cells

Protein glycosylation is a ubiquitous post‐translational modification that is involved in the regulation of many aspects of protein function. In order to uncover the biological roles of this modification, imaging the glycosylation state of specific proteins within living cells would be of fundamental importance. To date, however, this has not been achieved. Herein, we demonstrate protein‐specific detection of the glycosylation of the intracellular proteins OGT, Foxo1, p53, and Akt1 in living cells. Our generally applicable approach relies on Diels–Alder chemistry to fluorescently label intracellular carbohydrates through metabolic engineering. The target proteins are tagged with enhanced green fluorescent protein (EGFP). Förster resonance energy transfer (FRET) between the EGFP and the glycan‐anchored fluorophore is detected with high contrast even in presence of a large excess of acceptor fluorophores by fluorescence lifetime imaging microscopy (FLIM).     

Generation of femtosecond pulses by two-photon pumping supercontinuum-seeded collinear traveling wave amplification in a dye solution

Visible femtosecond (fs) laser pulses have been obtained in a dye solution with a very simple traveling wave collinear configuration. A femtosecond Ti:sapphire laser (790 nm) pumps the dye solution by two-photon absorption and simultaneously generates supercontinuum, which seeds a light-amplification mechanism. Cross-correlation frequency-resolved optical gating measurements reveal a chirped structure in the dye pulse. The shortest pulse duration achieved is 170 fs and the overall energy efficiency of the process is typically 25%. Received: 22 March 2001 / Revised version: 4 July 2001 / Published online: 19 September 2001     

Organogelators and Polymer Crystallisation

The specific impact of low molecular weight organic gels on polymer crystallisation is examined. Conventional nucleating agents (NA) influence the polyolefins crystallisation and improve their mechanical properties, via an epitaxial mechanism. In the particular case where the pair NA/polymer form a gel at intermediate temperatures on cooling, optical properties (clarity) are significantly improved. This improvement is linked with the ability of organic gels to develop 3-D fibrillar network. The fibres morphology offers a large specific area, thus produces a high density of nuclei, homogeneously dispersed. Gelling organic molecules are certainly a promising route towards the design of efficient additives in polymer processing.     

Determination of the Gamow–Teller strength function for the neutron-deficient isotopes In

The Gamow–Teller β decays of the neutron-deficient indium isotopes ^104–107In have been investigated by using total absorption γ-ray spectrometry on mass-separated sources. The experimental Gamow–Teller strength, deduced as a function of the excitation energy in the daughter nuclei ^104–107Cd, is compared to shell-model predictions.     

Structure and properties of semicrystalline polymers via high-frequency acoustic and x-ray measurements. I. Ferroelectric P(VDF/TrFE) copolymer

Acoustic, opto-acoustic, and x-ray investigations have been performed in order to study the influence of irradiation, electrical poling, and mechanical orientation on the morphology of ferroelectric random copolymers of vinylidene fluoride and trifluorethylene {P[VDF/TrFE] (70/30)}. The influences of these different treatments on the molecular orientation distribution of the amorphous and crystalline phases are discussed, as well as their influences on the crystallinity of the material. The elastic stiffness and the related viscosity tensors of P[VDF/TrFE] (70/30), the elastic stiffness modulus of the amorphous matrix, and the hierarchy of stiffness constants of the crystalline state have been determined. © 1993 John Wiley & Sons, Inc.     

Polymer decoration: The orientation of polymer folds as revealed by the crystallization of polymer vapors

A new technique of decoration of the fold surface of polymer crystals is described. It is similar in methodology to gold decoration, but makes use of vapors of crystallizable polymers, principally polyethylene, as decorating material. Upon condensation and crystallization, the highly anisometric decorating molecules become oriented parallel to the fold direction. They build up small crystalline lamellae which, seen edge-on, appear as elongated rods and can be easily observed by conventional transmission electron microscopy. This decoration technique reveals the sectorization of polymer single crystals grown from solution. It can be used to determine the local fold orientation (with a resolution of ca. 10 nm) of polymers crystallized under a wide range of conditions, including crystallization from the bulk. The technique reveals that under all crystallization conditions so far investigated the outermost part of the polymer fold surface is relatively ordered, and the folds and/or loops are, as a rule, oriented nearly parallel to the macroscopic growth front.     

Untersuchungen über das unterschiedliche Verhalten von N- und S-Methyliden gegenüber elektrophilen Reaktionspartnern

A straight forward synthesis of trimethylammonium trifluoroacetyl methylide (2) starting from trimethylammonium-di-trifluoracetyl methylide (1) using aniline is described. Moreover, the nucleophilic reactivity of N- and S-Ylides with identical anionic component towards acetylating agents were studied with respect to the contribution of the cationic component.

Herrn Prof. Dr.G. Zigeuner, Universität Graz, mit besten Wünschen zur Vollendung des 65. Lebensjahres gewidmet.     

Gamow-Teller strength distribution in the beta-decay of100Ag from total-absorption gamma spectrometry

The EC/β⁺-decay of the odd-odd nucleus¹⁰⁰Ag was studied by means of total absorptionγ-ray spectrometry. Most of the Gamow-Teller strength was found to be concentrated at an excitation energy of 5.6 MeV in¹⁰⁰Pd, the FWHM of this resonance being 1.5 MeV. The measured strength distribution which is interpreted within the BCS approximation as being due to the dominant population of four-quasiparticle excitations, resembles the distribution predicted by an advanced shell-model calculation for the⁹⁸Ag →⁹⁸Cd decay.