2‐Hydroxytorularhodin,a New Xanthophyll from the Red Yeast Sporobolomyces coprosmae

A new hydroxylated carotenoic acid was isolated from the red yeast Sporobolomyces coprosmae and unambiguously identified as 2‐hydroxytorularhodin ( 1 ), i.e., (all‐E)‐3′,4′‐didehydro‐2‐hydroxy‐β,ψ‐caroten‐16′‐oic acid, by application of extensive 1D and 2D NMR techniques (gCOSY, gHSQC, gHMBC, DQS, gTOCSY, and ROESY). Hydroxylation of carotenoids at C(2) is uncommon in nature, very rare in fungi, and unprecedented for torularhodin.     

Asymptotic Analysis of the Lyapunov Exponents of Certain Linear Hamiltonian Systems with Small Noise

In the paper there are considered linear Hamiltonian systems in R²ⁿ which include a small additive random term depending on a stationary ergodic Markov process. Under some regularity assumptions we derive asymptotic expansions for certain Lyapunov exponents of the systems (or for sums of them). The method used here is also applicable to the asymptotic analysis of a generalized rotation number.     

Isoproteins and an isoelectric focusing mutant of human apoprotein serum amyloid A

On isoelectric focusing of human plasma and subsequent immunoblotting, using antii-human serum amyloid A (SAA) antibodies, a genetic variant of SAA was detected in a family of Turkish origin. All affected members of the family were apparent heterozygotes for the mutant protein, which underwent a charge shift of about one charge unit toward the anode. The variant is likely to be a mutant of the most prominent forms of SAA (SAA1 and SAA2, or SAA1 and SAA1 des Arg). The appearance of a genetic variant of two of the six reported SAA-isoforms in human plasma supports the concept of SAA proteins being products of different genes.     

A mean-field theory for strongly disordered non-frustrated antiferromagnets

Motivated by impurity-induced magnetic ordering phenomena in spin-gap materials like TlCuCl₃, we develop a mean-field theory for strongly disordered antiferromagnets, designed to capture the broad distribution of coupling constants in the effective model for the impurity degrees of freedom. Based on our results, we argue that in the presence of random magnetic couplings the conventional first-order spin-flop transition of an anisotropic antiferromagnet is split into two transitions at low temperatures, associated with separate order parameters along and perpendicular to the field axis. We demonstrate the existence of either a bicritcal point or a critical endpoint in the temperature–field phase diagram, with the consequence that signatures of the spin flop are more pronounced at elevated temperature.     

Diterpenoids from Coprinus heptemerus

Seven diterpenoids, isolated due to their ability to inhibit spore germination in the plant pathogenic fungus Magnaporthe grisea, were obtained from cultures of the basidiomycete Coprinus heptemerus. The structures of the compounds, named heptemerones A-G, were determined with spectroscopic techniques.     

Zum strukturellen Verformungsverhalten einiger Tonmineral-Wasser-Systeme

Zusammenfassung Das Verformungsverhalten von plastischen Ton-Wasser-Systemen wurde mittels Parallelplattenplastometer in Retardations- und Entlastungsversuchen bestimmt. Dabei wurden die Mineralart, Kationenbelegung und Oberfläche sowie der Wassergehalt berücksichtigt. Durch verschiedene Auswertungsmethoden konnten Aussagen über einen stoffabhängigen kritischen Wassergehalt und über das Bindevermögen gewonnen werden. Die elastische Deformation in Verbindung mit den obigen Ergebnissen vermittelt Erkenntnisse über die strukturellen Eigenschaften.

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Summary The deforming behaviour of plastic clay-water-systems was determined by a parallel plate plastometer in retardation and discharging tests considering the kind of mineral, the loading with cations, the surface, and the water content. By different methods of evaluation it was possible to achieve results concerning a critical water content, depending on the material, as well as concerning the binding power. The elastic deformation in connection with the above mentioned results gives knowledge about the structural characteristics.

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Mit 14 Abbildungen und 4 Tabellen     

Antifading embedding media in confocal immunoflourescence microscopy

Fading or bleaching of fluorescence intensity during continuous illumination of stained objects is a serious problem in fluorescence microscopy. Fluorescence intensity as well as bleaching characteristics of dyes are dependent primarily upon physical parameters such as molecular constants (absorption rate and quantum efficiency), excitation energy and brightness (causes photon saturation), and environmental parameters (pH, ions, binding to proteins, etc.) that can strongly influence the properties of fluorochrome molecules. We have studied the effect of various antifading reagents on the behavior of the common dyes fluorescein isothiocyanate (FITC) and phycoerythrin (PE) using immunofluorescent-stained living cells in suspension or membrane-permeabilized dried cells as test systems. As expected, fading cannot be completely eliminated but may be reduced to varying degrees. In our hands, the most efficient antifading reagent for FITC isn-propyl gallate (NPG) dissolved in glycerol. No additive was found to retard fading, but complete dehydration of the cell suspension reduces this effect.