How the geometrical model for plant cell wall formation enables the production of a random texture

Cellulose synthase (CESA) molecules are the building blocks and catalytic centers of the CESA complex. The study of mutants in Arabidopsis has led to insight into the structure of these nanomachines. Inside the plasma membrane, the CESA molecules are arranged in complexes, which, apart from the CESA molecules proper, contain other, mostly unidentified, proteins. We developed a theory in which CESA density, together with distance between cellulose microfibrils (CMFs) being deposited and cell geometry, determines wall texture. We have shown earlier how this theory is able to explain the production of axial, helical, helicoid and crossed-polylamellate textures. In the present article we extend this theory to random wall textures.     

Control of diameter,morphology, and structure of PVDF nanofiber fabricated by electrospray deposition

Poly(vinylidene fluoride) (PVDF) nanofibers were prepared by electrospray deposition (ESD). To control the diameter, morphology, and structure of PVDF nanofibers, some parameters were investigated, such as polymer concentration, nozzle‐to‐ground collector distance, feeding rate of the polymer solution, and applied voltage. The fabricated fiber was 80–700 nm in diameter. The increase in the polymer concentration caused an increase in the polymer viscosity and fiber diameter. At low polymer concentration (5 wt %), polymer nanoparticles were formed. An increase in applied voltage will increase the fiber diameter. Variation in the nozzle‐to‐ground collector distance did not result in significant changes in the fiber diameter. Increase in the feeding rate of the polymer solution decreased the fiber diameter. Differential scanning calorimetry (DSC) and wide angle X‐ray diffraction (WAXD) measurements showed that the melting point and total crystallinity were decreased. Fourier transform infrared spectroscopy (FTIR) measurement revealed that ESD process induced the formation of the oriented β‐phase PVDF structures. It was also demonstrated that the addition of hydrofluorocarbon solvent to polymer solution remarkably enhanced the formation of β‐phase crystalline structure of PVDF nanofiber. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 779–786, 2006     

Discrimination of conventional and organic white cabbage from a long-term field trial study using untargeted LC-MS-based metabolomics

The influence of organic and conventional farming practices on the content of single nutrients in plants is disputed in the scientific literature. Here, large-scale untargeted LC-MS-based metabolomics was used to compare the composition of white cabbage from organic and conventional agriculture, measuring 1,600 compounds. Cabbage was sampled in 2 years from one conventional and two organic farming systems in a rigidly controlled long-term field trial in Denmark. Using Orthogonal Projection to Latent Structures–Discriminant Analysis (OPLS-DA), we found that the production system leaves a significant (p?=?0.013) imprint in the white cabbage metabolome that is retained between production years. We externally validated this finding by predicting the production system of samples from one year using a classification model built on samples from the other year, with a correct classification in 83 % of cases. Thus, it was concluded that the investigated conventional and organic management practices have a systematic impact on the metabolome of white cabbage. This emphasizes the potential of untargeted metabolomics for authenticity testing of organic plant products.     

Detection of small RNA molecules by a combination of branched rolling circle amplification and bioluminescent pyrophosphate assay

Polyfluorinated compounds (PFCs) are a relatively new and diverse set of compounds analyzed as contaminants in food. Their unique physical-chemical properties dictate the methods used for their analysis. Current analyses of the more volatile PFCs involve gas chromatography–mass spectrometry; liquid chromatography–tandem mass spectrometry is generally used for the less volatile PFCs. Considerations in the analysis of PFCs in foods include contamination from the widespread presence of materials that contain various PFCs, endogenous interfering compounds, and matrix effects. Future opportunities for research on PFCs in food exist, particularly in the areas of biological molecule–PFC interactions and the effects of food processing on these interactions. Future research will be facilitated by the synthesis of a wider variety of analytical standards.     

Synthetic procedure for various selenium-containing electron donors of the bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) type

Six selenium variants of BEDT-TTF have been successfully synthesized by a newly developed synthetic method that involves a combination of two key reactions for the construction of two kinds of heterocyclic rings: the first is a one-pot formation of 1,3-dichalcogenole-2-chalcogenones from a common starting material, THP-protected 2-(ethynylthio)ethanol, leading to the inner five-membered rings, and the other is the annelation of the outer six-membered heterocyclic ring onto the inner ring by an intramolecular transalkylation reaction on a chalcogen atom. This method turned out to be widely applicable to the syntheses of the electron donors of bis(ethylenedithio)- and bis(ethyleneselenothio)-substituted types. However, synthetic attempts to form analogous donors of the bis(ethylenediseleno)-substituted type from THP-protected 2-(ethynylseleno)ethanol were unsuccessful. This is attributable to the predominance of side-reactions via a seleniranium (episelenonium) salt over the desired six-membered ring formation by transalkylation via a seleninium salt.     

Infrared spectroscopic investigation of poly(2-methoxyethyl vinyl ether) during thermosensitive phase separation in water

Hydration changes of poly(2-methoxyethyl vinyl ether) (PMOVE) synthesized via living cationic polymerization have been investigated during a temperature-responsive phase separation in water by using infrared spectroscopy. An aqueous PMOVE solution has lower critical solution temperatures (LCSTs) of 66 degrees C in H2O and 65 degrees C in D2O at approximately 15 wt %. During phase separation, the C-H stretching (nu(C-H)) bands of PMOVE shift downward (red shift). In particular, the IR band assigned to the antisymmetric stretching vibration of the terminal methyl groups exhibits a remarkably large red shift by 16 cm-1. The band also exhibits a red shift with increasing polymer concentration at T < Tp. Density functional theory (DFT) calculations of the models of hydrated PMOVE indicate that the shift is due mainly to the breaking of hydrogen bonds (H-bonds) between the oxygen of the methoxy groups and water and partially to the breaking of the CH...O H-bond to them.     

Gold sputtered electrode surfaces enhance direct electron transfer reactions of human cytochrome P450s

We immobilized human cytochrome P450 (CYP), a membrane-bound enzyme, onto both smooth and nanostructured surfaces of gold electrodes via a naphthalene thiolate monolayer film. Rapid electron transfer of CYP with an electrode as a redox partner took place when the enzyme was immobilized onto an electrode surface with nanostructures. This structure was easily prepared by conventional sputtering techniques. A well-defined pair of peaks was observed at ? 0.175 V (vs. SHE) with the largest heterogeneous electron transfer rate constant of 340 s^? 1 for human CYP. The positive redox potential shift of 45 mV upon drug (testosterone) binding was clearly detected, which corresponded to a change in the spin states of heme iron in CYP. The present study showed that gold sputtered surfaces are very useful for direct electron transfer reactions of human CYP isoforms.     

Targeted Gene Delivery via PEI Complexed with an Antibody

Stable carriers are required for gene delivery. The use of polyethyleneimine (PEI) has been researched extensively; however, it is not suitable for targeted gene delivery to specific cells. To provide a targeting ability of the specific antibody to PEI, two repeats of Fc-binding domain of protein G (C2) were utilized. The constructed protein containing C2 could bind to a specific antibody and form a larger complex with plasmid DNA/PEI complex. The specific antibody to cell surface protein was bound to the complex through the use of C2 domain, and it was added to cells. As the result, the efficient expression of delivered reporter gene could be realized.     

Formation of gold-capped silicon nanocolumns on silicon substrate

Gold-capped silicon nanocolumns regularly distributed over silicon substrate were obtained. The columns length was roughly 100?nm; their deviation from perpendicular axis was less than 2°. The diameter of the columns was of the order of 10?nm or below of that. The proposed procedure of nanostructuring included the following main steps: deposition of aluminum thin layer (100?C500?nm) by magnetron sputtering on (100) oriented Si wafers; formation of porous self-ordered alumina structures by electrochemical anodizing of the Al film in oxalic acid; electroless inversion of Au in alumina pores; and reactive ion etching. The obtained Si?CAu structures are of importance as the platforms for biosensing applications, while the gold-free structures are of interest in photovoltaics.     

Selection of DNA Aptamers with Affinity for Pro-gastrin-Releasing Peptide (proGRP), a Tumor Marker for Small Cell Lung Cancer

Aptamers are single-strand oligonucleotides that are generated by the systemic evolution of ligands by exponential enrichment (SELEX) technique and that can bind to target molecules specifically. However, only a few aptamers have been developed to date against tumor markers. To utilize aptamers for tumor diagnosis, a variety of aptamers are required. Here, a single-stranded DNA aptamer specific for pro-gastrin-releasing peptide (proGRP), a marker for small cell lung cancer, was selected using SELEX. After selection, identical sequences were found in the DNA library. This sequence was selected and its binding affinity to proGRP was evaluated using surface plasmon resonance.