Integrating toxin gene expression,growth and fumonisin B1 and B2 production by a strain of Fusarium verticillioides under different environmental factors

The objective of this study was to integrate data on the effect of water activity (a_w; 0.995–0.93) and temperature (20–35°C) on activation of the biosynthetic FUM genes, growth and the mycotoxins fumonisin (FB₁, FB₂) by Fusarium verticillioides in vitro. The relative expression of nine biosynthetic cluster genes (FUM1, FUM7, FUM10, FUM11, FUM12, FUM13, FUM14, FUM16 and FUM19) in relation to the environmental factors was determined using a microarray analysis. The expression was related to growth and phenotypic FB₁ and FB₂ production. These data were used to develop a mixed-growth-associated product formation model and link this to a linear combination of the expression data for the nine genes. The model was then validated by examining datasets outside the model fitting conditions used (35°C). The relationship between the key gene (FUM1) and other genes in the cluster (FUM11, FUM13, FUM9, FUM14) were examined in relation to a_w, temperature, FB₁ and FB₂ production by developing ternary diagrams of relative expression. This model is important in developing an integrated systems approach to develop prevention strategies to control fumonisin biosynthesis in staple food commodities and could also be used to predict the potential impact that climate change factors may have on toxin production.     

On the relationship between wavelength and perceived hue

Unlike in the case of sound where there is a compressed but straightforward relationship between frequency of sound waves and the perceived pitch, in the case of color the relationship is highly nonlinear, as first pointed out by Ostwald in 1916. In this article, the relationship between the perceptual Munsell hue scale and the related dominant wavelengths of the color chips involved is investigated. A hypothesis is proposed according to which the immediate cause of the nonlinearity can be found in the relative activation of the kinds of chromatically opponent functions shown to exist in neurons of the lateral geniculate nuclei. However, at this time, the relationship is only correlational, given the lack of deeper understanding of the relationship between the physiological operation of the color vision system and conscious experiences of color. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2011;     

Identification and Avoidance of Systematic Measurement Errors in Lamb Wave Observation With One‐Dimensional Scanning Laser Vibrometry

Abstract: Scanning laser vibrometry is a widely used tool to observe Lamb wave fields for structural health monitoring (SHM) purposes. Lamb waves propagate over long distances in thin‐walled structures and interact with structural inhomogeneities, for example, damages, in spite of wavelengths several times of the damage size. In SHM of sheets and glass‐ or carbon‐fibre‐reinforced plastic plates, this effect is used for determining the position as well as the size of structural faults. With the often employed one‐dimensional vibrometry, a geometrically induced, systematic error occurs when measuring oblique‐angled motion. This error can be, in the specific case of Lamb waves, of a non‐negligible quantity. The nature of this geometrical measurement error in general and concerning Lamb waves in special is discussed analytically for both amplitude and phase data. It is shown that this matter should be taken into account in some applications.     

The Dysfunctional Leica

Abstract

Winding up the estate of somebody is a sad task, only sustained by the hope of unexpected finds or definitive proof of one's preconceived opinions. There is no difference in this between one's own grandmother and a contemporary like Lucia Moholy. While executing this task I naturally came across various documents that shifted my vague assumptions about this versatile woman in different directions. I saw photographs from her private life that enlightened me about her social relations but, in the end, I was disappointed at not havlng been able to get closer to a person I thought I knew quite well, even if from a certain distance.¹     

Tracking Protein S‐Fatty Acylation with Proteomics

Recently, Hang and co‐workers developed “acyl‐PEG exchange” (APE), which allows the investigation of protein S‐fatty acylation with mass‐tag labelling and gel electrophoresis, methods that are accessible to any biochemistry laboratory.     

Structure and Substrate Recognition of the Bottromycin Maturation Enzyme BotP

The bottromycins are a family of highly modified peptide natural products, which display potent antimicrobial activity against Gram‐positive bacteria, including methicillin‐resistant Staphylococcus aureus. Bottromycins have recently been shown to be ribosomally synthesized and post‐translationally modified peptides (RiPPs). Unique amongst RiPPs, the precursor peptide BotA contains a C‐terminal “follower” sequence, rather than the canonical N‐terminal “leader” sequence. We report herein the structural and biochemical characterization of BotP, a leucyl‐aminopeptidase‐like enzyme from the bottromycin pathway. We demonstrate that BotP is responsible for the removal of the N‐terminal methionine from the precursor peptide. Determining the crystal structures of both apo BotP and BotP in complex with Mn²⁺ allowed us to model a BotP/substrate complex and to rationalize substrate recognition. Our data represent the first step towards targeted compound modification to unlock the full antibiotic potential of bottro‐ mycin.     

Molecular Cross-Talk between Gravity- and Light-Sensing Mechanisms in Euglena gracilis

Euglena gracilis is a photosynthetic flagellate. To acquire a suitable position in its surrounding aquatic environment, it exploits light and gravity primarily as environmental cues. Several physiological studies have indicated a fine-tuned relationship between gravity sensing (gravitaxis) and light sensing in E. gracilis. However, the underlying molecular mechanism is largely unknown. The photoreceptor photoactivated adenylyl cyclase (PAC) has been studied for over a decade. Nevertheless, no direct/indirect interaction partner (upstream/downstream) has been reported for PAC. It has been shown that a specific protein, kinase A (PKA), showed to be involved in phototaxis and gravitaxis. The current study reports the localization of the specific PKA and its relationship with PAC.     

119Sn-NMR spektroskopische Untersuchungen an Tributylzinnderivaten aromatischer Sulfonsäuren

¹¹⁹Sn-NMR Spectroscopic Investigations of Tributyltin Derivatives of Aromatic Sulfonic Acids . Tributyltin derivatives of nine aromatic sulfonic acids were synthesized and investigated by means of ¹¹⁹Sn-n.m.r. spectroscopy. ¹¹⁹Sn-chemical shifts and ¹J (Sn, C) coupling constants in dependence on temperature and concentration were applied to study the association processes of the substances in solution. In CDCl₃ as a solvent a monomeric/polymeric equilibrium of the substances was demonstrated, while CD₃OD as a donor solvent forms five-coordinated complexes with the tin compounds.     

Measurements of the Refractive Index Increment on Hydroxyethyl Starch as a Basis for Absolute Molecular Weight Determinations

Solutions of hydroxyethyl starch are used as a blood plasma substitute. If their physiological efficiency is to be optimized, they need to be accurately characterized in terms of their molecular weight and its distribution. The absolute determination of molecular weight and molecular weight distribution by means of light scattering require a knowledge of the refractive index increment. Although numerous investigations of the refractive index increment of hydroxyethyl starch have already been published, the results vary significantly due to the use of different samples and the choice of different measuring parameters. There was therefore an urgent need to examine the extent to which the refractive index increment depends on molecular parameters, the experimental method used and the type of processing. Here it was found that different sample preparations result in different contents of solid matter, so that an exact determination of the quantity is required. Hydroxyethyl starches in the molecular weight range of about Mw = 200.000 g/mol and varying degrees of substitution between DS 0.38 and 0.50 which are regarded as optimal for clinical use give a refractive index increment of dn/dc^633nm = 0.146 = 0.005 cm³/g (solvent: H₂O/0.02% NaN₃; T = 25°C).