2005 Bunsen–Kirchhoff Award for Analytical Spectroscopy

Announcement

2005 Bunsen–Kirchhoff Award for Analytical SpectroscopyDASp Deutscher Arbeitskreis für angewandte Spektroskopie     

Are iridoids in leaf beetle larvae synthesized de novo or derived from plant precursors? A methodological approach

Iridoids, belonging to a group of cyclopentanoid monoterpenoids, are secreted by many species of leaf beetles as a defense against predators. Using chemically modified precursors of iridoid biosynthesis, it has been shown that some leaf beetle larvae can synthesize these iridoids de novo as well as sequester plant-produced molecules. Stable isotope techniques can provide useful methods for studying terpenoid biosynthesis without disturbing the natural conditions much. Two terpenoid biosynthesis pathways (mevalonic acid (MVA) pathway and methylerythritol-4-phosphate (MEP) pathway) may lead to different delta13C signatures of the products. Our results from natural abundance 13C and 13C-labelled iridoid precursors in Gastrophysa viridula and Phaedon cochleariae suggested that the two leaf beetle species use only de novo synthesis of their defensive iridoids. We observed that the isotope signature of the leaf-beetle-produced iridoids (via the MVA pathway) resembled that of the MEP-derived monoterpenoids from plants. Owing to this close similarity in the natural 13C abundances in the plant and insect compounds, a determination of iridoid-origin in leaf beetle secretion may only be possible by use of isotopically labelled compounds.     

Permutation Sign under the Robinson-Schensted Correspondence

We show how the sign of a permutation can be deduced from the tableaux induced by the permutation under the Robinson-Schensted correspondence. The result yields a simple proof of a conjecture on the squares of imbalances raised recently by Stanley.AMS Subject Classification: 05E10, 05A15.     

Soy isoflavone glycitein protects against beta amyloid-induced toxicity and oxidative stress in transgenic <Emphasis Type="Italic">Caenorhabditis elegans</Emphasis>

Background  

Epidemiological studies have associated estrogen replacement therapy with a lower risk of developing Alzheimer's disease, but a higher risk of developing breast cancer and certain cardiovascular disorders. The neuroprotective effect of estrogen prompted us to determine potential therapeutic impact of soy-derived estrogenic compounds. Transgenic C. elegans, that express human beta amyloid (Aβ), were fed with soy derived isoflavones genistein, daidzein and glycitein (100 μg/ml) and then examined for Aβ-induced paralysis and the levels of reactive oxygen species.     

Structure of Escherichia coli dUTPase in Solution: A Small Angle Neutron Scattering Study

The present study investigates shape properties of the enzyme dUTPase from Escherichia coli in the solution phase. In this work small angle neutron scattering (SANS) findings on dUTPase/D₂O solutions for temperature values of T = 8 °C and T = 37 °C are presented. The analysis of SANS data, carried out by using a prolate ellipsoid core/shell model fitting and the well‐known Guinier and Zimm analysis procedures allows the characterization of the shape of the protein in solution. By means of the comparison with experimental and theoretical data existing in literature on dUTPase in the crystalline state, we find that the protein in solution maintains its dimensions before the denaturation process. Furthermore, by analyzing the SANS spectra of dUTPase/D₂O/trehalose solutions, we emphasize the bioprotective effects of trehalose on the protein.

Structure of dUTPase.     

Multielement ultratrace analysis in tungsten using secondary ion mass spectrometry

Summary The ever increasing demands on properties of materials creates a trend also towards ultrapure products. Characterization of these materials is only possible with modern, highly sophisticated analytical techniques such as activation analysis and mass spectrometry, particularly SSMS, SIMS and GDMS [1].Analytical strategies were developed for the determination of about 40 elements in a tungsten matrix with high-performance SIMS. Difficulties like the elimination of interferences had to be overcome. Extrapolated detection limits were established in the range of pg/g (alkali metals, halides) to ng/g (e. g., Ta, Th).Depth profiling and ion imaging gave additional information about the lateral and the depth distribution of the elements.

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Multielementepurenanalyse in Wolfram mittels SIMS

     

Some new fundamental solutions

The fundamental solutions of non-decomposable evolution operators are represented by multi-dimensional parameter integration formulae. The method is applied to operators occurring in the theories of elasticity, magnetohydrodynamics and heat conduction.     

Influence of freezing of aqueous samples on the Fe(II)/Fe(III) equilibrium

The influence of freezing of aqueous samples on the Fe(II)/Fe(III) equilibrium has been investigated by ion chromatography. No change has been observed in the pH-range 2–5, irrespective of the freezing temperature.     

Oxygen determination in calcium fluoride by deuteron activation analysis

Oxygen at trace level in calcium fluoride was determined by instrumental deuteron activation analysis based on the 16O(d,n)17F reaction. The irradiations were performed with 2.5 MeV deuterons for 60 s at currents ranging from 300 to 500 nA. The results obtained for powders and single crystals were compared.