Using unnatural protein fusions to engineer resveratrol biosynthesis in yeast and Mammalian cells

Resveratrol is a naturally occurring defense compound produced by a limited number of plants in response to stresses. Besides cardiovascular benefits, this health-promoting compound has been reported to extend life spans in yeasts, flies, worms, and fish. To biosynthesize resveratrol de novo, tyrosine ammonia lyase (TAL), 4-coumarate CoA-ligase (4CL), and stilbene synthase (STS) were isolated from Rhodobacter sphaeroides, Arabidopsis thaliana, and Vitis vinifera, respectively. Yeast cells expressing 4CL and STS produce resveratrol when fed with 4-coumaric acid, the substrate of 4CL. When a translational fusion protein joining 4CL and STS was used, yeast cells produced 15-fold more resveratrol than the cotransformed cells, suggesting that physical localization of 4CL and STS facilitate resveratrol production. When the resveratrol pathway was introduced into human HEK293 cells, de novo biosynthesis was detected, leading to intracellular accumulation of resveratrol. We successfully engineered an entire plant natural product pathway into a mammalian host.     

Spatial contagion between financial markets: a copula‐based approach

A method is proposed for defining and investigating spatial contagion between two financial markets X and Y by using the information contained in their copula. A practical illustration of the introduced method is also given by examining the presence of contagion among two European stock indices (namely, FTSE 100 and DAX). Copyright © 2009 John Wiley & Sons, Ltd.     

Hierarchical self-assembly of a biomimetic diblock copolypeptoid into homochiral superhelices

The aqueous self-assembly of a sequence-specific bioinspired peptoid diblock copolymer into monodisperse superhelices is demonstrated to be the result of a hierarchical process, strongly dependent on the charging level of the molecule. The partially charged amphiphilic diblock copolypeptoid 30-mer, [N-(2-phenethyl)glycine](15)-[N-(2-carboxyethyl)glycine](15), forms superhelices in high yields, with diameters of 624 ± 69 nm and lengths ranging from 2 to 20 μm. Chemical analogs coupled with X-ray scattering and crystallography of a model compound have been used to develop a hierarchical model of self-assembly. Lamellar stacks roll up to form a supramolecular double helical structure with the internal ordering of the stacks being mediated by crystalline aromatic side chain-side chain interactions within the hydrophobic block. The role of electrostatic and hydrogen bonding interactions in the hydrophilic block is also investigated and found to be important in the self-assembly process.     

A new model of cavern diameter based on a validated CFD study on stirring of a highly shear-thinning fluid

Results of numerical simulations of momentum transfer for a highly shear-thinning fluid (0.2% Carbopol) in a stirred tank equipped with a Prochem Maxflo T type impeller are presented. The simulation results were validated using LDA data and both tangential and axial force measurements in the laminar and early transitional flow range. A good agreement between the predicted and experimental results of the local fluid velocity components was found. From the predicted and experimental values of both tangential and axial forces, the power number, Po, and thrust number, Th, were also calculated. Values of the absolute relative deviations were below 4.0 and 10.5%, respectively, for Po and Th, which confirms a satisfactory agreement with experiments. An intensive mixing zone, known as cavern, was observed near the impeller. In this zone, the local values of fluid velocity, strain rate, Metzner–Otto coefficient, shear stress and intensity of energy dissipation were all characterized by strong variability. Based on the results of experimental study a new model using non-dimensional impeller force number was proposed to predict the cavern diameter. Comparative numerical simulations were also carried out for a Newtonian fluid (water) and their results were similarly well verified using LDA measurements, as well as experimental power number values.     

Facile Synthesis of 2-Substituted cis-2-cyclopentene-1,4-diol Derivatives

2-Substituted cis-2-cyclopentene-1,4-diol derivatives are used as starting materials for prostaglandin synthesis¹. Two papers concerning the synthesis of these compounds have been published so far ^1,2. In this paper we would like to present an alternative method for synthesis of 2-substituted cis-2-cyclopen-tene-1,4-diols from easily available cis-2-cyclopentene-1, 4-diol diacetate 1 ³.     

Spin-seebeck effect: a phonon driven spin distribution

Here we report on measurements of the spin-Seebeck effect in GaMnAs over an extended temperature range alongside the thermal conductivity, specific heat, magnetization, and thermoelectric power. The amplitude of the spin-Seebeck effect in GaMnAs scales with the thermal conductivity of the GaAs substrate and the phonon-drag contribution to the thermoelectric power of the GaMnAs, demonstrating that phonons drive the spin redistribution. A phenomenological model involving phonon-magnon drag explains the spatial and temperature dependence of the measured spin distribution.     

Peptide retention prediction applied to proteomic data analysis

A retention prediction model was developed for peptides separated in reversed-phase chromatography. The model was utilized to identify and exclude the false positive (FP) peptide identifications obtained via database search. The selected database included human proteins, as well as decoy sequences of random proteins. The FP peptide detection rate was defined either as number of retention time outliers, or random decoy sequence identifications. The FP rate for various MASCOT scores was calculated. The peptides identified in one-dimensional (1D) and two-dimensional (2D) liquid chromatography/mass spectrometry (LC/MS) experiments were validated by prediction models. Multi-dimensional LC was based on two orthogonal reversed-phase chromatography modes; prediction models were successfully applied for data filtering in both separation dimensions.