LanV, a bifunctional enzyme: aromatase and ketoreductase during landomycin A biosynthesis

LanV is involved in the biosynthesis of landomycin A. The exact function of this enzyme was elucidated with combinatorial biosynthesis by using Streptomyces fradiae mutants that produce urdamycin A. After expression of lanV in S. fradiae DeltaurdM, which is a mutant that accumulates rabelomycin, urdamycinon B and urdamycin B were found to be produced by the strain. This result indicates that LanV is involved in the 6-ketoreduction of the angucycline core, which preceeds a 5,6-dehydration reaction. 9-C-D-Olivosyltetrangulol was also produced by this strain; this demonstrates that LanV catalyses the aromatization of ring A of the angucycline structure. Coexpression of lanV and lanGT2 in S. fradiae AO, a mutant that lacks all four urdamycin glycosyltransferases, resulted in the production of tetrangulol and the glycoside landomycin H, both of which have an aromatic ring A. As glycosylated angucyclines were not observed after expression of lanGT2 in the absence of lanV, we conclude that LanGT2 needs an aromatized ring A for substrate recognition.     

Activated Chemical Defense in Aplysina Sponges Revisited

Sponges of the genus Aplysina accumulate brominated isoxazoline alkaloids in concentrations that sometimes exceed 10% of their dry weight. We previously reported a decrease in concentrations of these compounds and a concomitant increase in concentrations of the monocyclic nitrogenous compounds aeroplysinin-1 and dienone in Aplysina aerophoba following injury of the sponge tissue. Further investigations indicated a wound-induced enzymatic cleavage of the former compounds into the latter, and demonstrated that these reactions also occur in other Aplysina sponges. A recent study on Caribbean Aplysina species, however, introduced doubt regarding the presence of a wound-induced bioconversion in sponges of this genus. This discrepancy motivated us to reinvestigate carefully the fate of brominated alkaloids in A. aerophoba and in other Aplysina sponges following mechanical injury. As a result of this study we conclude that (1) tissue damage induces a bioconversion of isoxazoline alkaloids into aeroplysinin-1 and dienone in Aplysina sponges, (2) this reaction is likely catalyzed by enzymes, and (3) it may be ecologically relevant as the bioconversion products possibly protect the wounded sponge tissue from invasion of bacterial pathogens.     

Phase imaging with intermodulation atomic force microscopy

Intermodulation atomic force microscopy (IMAFM) is a dynamic mode of atomic force microscopy (AFM) with two-tone excitation. The oscillating AFM cantilever in close proximity to a surface experiences the nonlinear tip-sample force which mixes the drive tones and generates new frequency components in the cantilever response known as intermodulation products (IMPs). We present a procedure for extracting the phase at each IMP and demonstrate phase images made by recording this phase while scanning. Amplitude and phase images at intermodulation frequencies exhibit enhanced topographic and material contrast.     

PY181 Pigment Microspheres of Nanoplates Synthesized via Polymer‐Induced Liquid Precursors

Organic pigments are important crystalline substances, and their properties and applications rely on size and shape control. Pigment Yellow 181 (PY181) is an industrial azo pigment that is light and weatherfast and suitable for high temperature processing. One disadvantage is its needle‐like shape in the default β‐phase, which makes the pigment difficult to process in industry, e.g., in polymer melts, where a spherical structure would be ideal. Here, we show for the first time, that polymer‐induced liquid precursor structures can be formed even in association to a chemical reaction. Furthermore, it is demonstrated that biomineralization principles can be exploited for the generation of advanced functional materials, such as pigments with novel complex morphology and different properties. Stable PY181 microspheres of nanoplates in the β‐phase were obtained in mixed solvents of water and isopropanol by direct azo coupling under the directing influence of a designed copolymer additive aminobenzoylaminobenzamide‐acetoacetyl‐poly(ethylene imine)‐block‐poly(ethylene glycol) (ABABA‐acetoacetyl‐PEI‐b‐PEG).     

Hepatic lipid composition differs between ob/ob and ob/+ control mice as determined by using in vivo localized proton magnetic resonance spectroscopy

Object

Hepatic lipid accumulation is associated with nonalcoholic fatty liver disease, and the metabolic syndrome constitutes an increasing medical problem. In vivo proton magnetic resonance spectroscopy (¹H MRS) allows the assessment of hepatic lipid levels noninvasively and also yields information on the fat composition due to its high spectral resolution.

Materials and methods

We applied ¹H MRS at 9.4T to study lipid content and composition in eight leptin-deficient ob/ob mice as a model of obesity and in four lean ob/+ control mice at 24?weeks of age. PRESS sequence was used. For accurate estimation of signal intensity, differences in relaxation behavior of individual signals were accounted for each mouse individually. Also, in order to minimize spectral degrading due to motion artifacts, respiration gating was applied.

Results

Significant differences between ob/ob and ob/+ control mice were found in both lipid content and composition. The mean chain length was found to be significantly longer in ob/ob mice with a higher fraction of monounsaturated lipids.

Conclusion

¹H MRS enables accurate assessment in hepatic lipids in mice, which is attractive for mechanistic studies of altered metabolism given the large number of genetically engineered mouse models available.     

Planung und Ausführung des Ersatzneubaus einer U‐Bahn‐Brücke in Berlin unter hohem Zeitdruck

Design and construction of a new bridge for the Berlin underground to replace an old structure under high time pressure. This paper is about the design and construction of a new bridge for the underground in Berlin. A new structure was necessary due to insufficient stability and serviceability of the old one. The project had to be carried out under high time pressure to avoid a decommissioning of the underground traffic. As a result of this the planning and execution phases were significantly reduced. Besides, the client provided the construction firm with the structural steel to be used for the superstructure, a potential for conflict that would need to be tackled. The project will be described from the design point of view.     

A Branched Tripeptide with an Anion-Binding Motif as a New Delivery Carrier for Efficient Gene Transfection

Branched and dendrimeric cationic peptides have shown better transfection efficiency than linear peptides, owing to their superior capacity for inducing DNA condensation. We have designed and synthesized two analogously guanidinocarbonylpyrrole-substituted (GCP-substituted) branched cationic tripeptides that provide extremely strong electrostatic attraction towards DNA. Both ligands 1 and 2 can bind to DNA and form condensed complexes, owing to the branched structure and high positive charges, as demonstrated by isothermal titration calorimetry (ITC), ζ potential and atomic force microscopy (AFM). After the replacement of the carboxylate group by an amide group, binding of ligand 2 to DNA shows exothermic enthalpy and positive entropy changes relative to ligand 1 . Rational interpretation would suggest that ligand 2 might aid the translocation of plasmid pF143 to HEK 293T cells, showing high gene transfection efficiency. This work therefore provides a facile way, by modifying a branched cationic tripeptide with GCP, to turn a peptide even a tripeptide into an efficient gene transfection vector.     

Innovations in margarines,shortenings and spreads

Product trends within the oils and fats segment are reviewed with special focus on two case studies which cover the production of low fat dairy spreads compounded from concentrated cream and vegetable oil, and the manufacturing of fat flakes based on palm oil fractions using innovative flake equipment.     

A calculus for modular loop acceleration and non-termination proofs

Loop acceleration can be used to prove safety, reachability, runtime bounds, and (non-)termination of programs. To this end, a variety of acceleration techniques have been proposed. However, so far all of them have been monolithic, i.e., a single loop could not be accelerated using a combination of several different acceleration techniques. In contrast, we present a calculus that allows for combining acceleration techniques in a modular way and we show how to integrate many existing acceleration techniques into our calculus. Moreover, we propose two novel acceleration techniques that can be incorporated into our calculus seamlessly. Some of these acceleration techniques apply only to non-terminating loops. Thus, combining them with our novel calculus results in a new, modular approach for proving non-termination. An empirical evaluation demonstrates the applicability of our approach, both for loop acceleration and for proving non-termination.