Glucosylation of Isoflavonoids in Engineered Escherichia coli

A glycosyltransferase, YjiC, from Bacillus licheniformis has been used for the modification of the commercially available isoflavonoids genistein, daidzein, biochanin A and formononetin. The in vitro glycosylation reaction, using UDP-α-D-glucose as a donor for the glucose moiety and aforementioned four acceptor molecules, showed the prominent glycosylation at 4′ and 7 hydroxyl groups, but not at the 5^th hydroxyl group of the A-ring, resulting in the production of genistein 4′-O-β-D-glucoside, genistein 7-O-β-D-glucoside (genistin), genistein 4′,7-O-β-D-diglucoside, biochanin A-7-O-β-D-glucoside (sissotrin), daidzein 4′-O-β-D-glucoside, daidzein 7-O-β-D-glucoside (daidzin), daidzein 4′, 7-O-β-D-diglucoside, and formononetin 7-O-β-D-glucoside (ononin). The structures of all the products were elucidated using high performance liquid chromatography-photo diode array and high resolution quadrupole time-of-flight electrospray ionization mass spectrometry (HR QTOFESI/MS) analysis, and were compared with commercially available standard compounds. Significantly higher bioconversion rates of all four isoflavonoids was observed in both in vitro as well as in vivo bioconversion reactions. The in vivo fermentation of the isoflavonoids by applying engineered E. coli BL21(DE3)/ΔpgiΔzwfΔushA overexpressing phosphoglucomutase (pgm) and glucose 1-phosphate uridyltransferase (galU), along with YjiC, found more than 60% average conversion of 200 μM of supplemented isoflavonoids, without any additional UDP-α-D-glucose added in fermentation medium, which could be very beneficial to large scale industrial production of isoflavonoid glucosides.     

Human Variation and Risk Assessment: Microarray and Other Studies Utilizing Human Hepatocytes and Human Liver Subcellular Preparations

The new paradigms proposed for human health risk assessment stress the need for the use of human and human‐derived cell lines, and this review summarizes the use of primary human hepatocytes and hepatocyte subcellular preparations for the investigation of the metabolism and metabolic interactions of environmental chemicals. This includes interactions based on inhibition, induction, and activation. The role of cytotoxicity is also considered. The use of hepatocytes and hepatocyte preparations provides especially important information for the investigation of human variation and is summarized. This area is, at present, relatively neglected but will in the future be essential for accurate assessment of human health risk. A detailed summary of an initial attempt to utilize microarray technology for the study of genome‐wide effects is included.     

An alkaline and metallo-protein type endo xylanase from Streptomyces sp. CSWu-1

An alkaline xylanase (XynWu-1) from Streptomyces sp. CSWu-1 was isolated from the Korean soil sample, purified and biochemically characterized. The extracellular xylanase was purified 4.8 fold with a 16% yield using Sephadex G-50 followed by DEAE-Sepharose (fast flow) column chromatography. The molecular mass of the enzyme was approximately 37 kDa estimated by SDS-PAGE and xylan zymography. N-terminal amino acid sequence of XynWu-1 was AINVLVAALX. The enzyme was found to be stable in a broad range of pH (7.0 ～ 13.0) and to 50°C and have an optimal pH and temperature of 11.0 and 60°C, respectively. XynWu-1 activity was found to be affected by Mn²⁺ ion with highest activity at 6 mM and produced xylose, xylobiose, and xylotetraose as major hydrolyzed end products. It was found to degrade agro waste materials like corncob and wheat bran by XynWu-1 (2,000 U/g) as shown by electron microscopy. As being stable in extreme alkaline pH, diverse peculiar biochemical characteristics, and ability to produce oligosaccharide shows that XynWu-1 has potential application in various bioindustries like probiotics, ethanol, etc.     

High‐Performance Semitransparent Tandem Solar Cell of 8.02% Conversion Efficiency with Solution‐Processed Graphene Mesh and Laminated Ag Nanowire Top Electrodes

A high‐performance semitransparent tandem solar cell that uses solution‐processed graphene mesh and laminated Ag NW as a transparent anode and cathode, respectively, is demonstrated. The laminated top electrode can be deposited without causing any damage to the underneath organic solar cells. Power conversion efficiencies of 8.02% and 6.47% are obtained when the light is projected from the solution‐processed graphene mesh and laminated AgNW, respectively. The performance of the tandem cell is found to be comparable to a tandem solar cell fabricated using commercially available indium tin oxide. These findings offer a high‐performance device and open a new pathway in searching for a potential replacement to the frequently used transparent conducting electrodes.     

Inhibition of nitric oxide production in LPS-stimulated RAW 264.7 cells by stem bark of Ulmus pumila L.

This study was designed to isolate and identify a potent inhibitory compound against nitric oxide (NO) production from the stem bark of Ulmus pumila L. Ethyl acetate fraction of hot water extract registered a higher level of total phenolics (756.93 mg GAE/g) and also showed strong DPPH (IC₅₀ at 5.6 μg/mL) and ABTS (TEAC value 0.9703) radical scavenging activities than other fractions. Crude extract and its fractions significantly decreased nitrite accumulation in LPS-stimulated RAW 264.7 cells indicating that they potentially inhibited the NO production in a concentration dependent manner. Based on higher inhibitory activity, the ethyl acetate fraction was subjected to Sephadex LH-20 column chromatography and yielded seven fractions and all these fractions registered appreciable levels of inhibitory activity on NO production. The most effective fraction F1 was further purified and subjected to ¹H, ¹³C-NMR and mass spectrometry analysis and the compound was identified as icariside E₄. The results suggest that the U. pumila extract and the isolated compound icariside E₄ effectively inhibited the NO production and may be useful in preventing inflammatory diseases mediated by excessive production of NO.     

On tradeoff between the two compromise factors in assigning tasks on a cluster computing

This paper deals with the static task-assignment problem in a cluster computing system as follows: Given a task composed of a number of interacting modules, assign the task modules to the processors in the system to minimize the communication cost while balancing the processors’ loads. Because these two optimization criteria conflict with each other, a compromise needs to be made between them according to the given task type. This paper proposes a new cost function to evaluate the static task assignments and a heuristic algorithm for solving the transformed problem explicitly describing the tradeoff between the two goals. The simulation results showed that this approach outperforms the existing representative approach for a range of tasks and processing systems.     

Dynamic kinetic resolutions and asymmetric transformations by enzymes coupled with metal catalysis

The combination of enzyme and metal catalysis is described as a useful method for the synthesis of optically active compounds. A key feature of this new methodology is the use of metal catalysts for the in situ racemization of enzymatically unreactive enantiomers in the enzymatic resolution of racemic substrates. So far, two combinations - lipase-ruthenium and lipase-palladium - have been developed for the efficient dynamic kinetic resolution of alcohols and amines. The use of these combinations has also been extended to catalysis of the asymmetric transformation of ketones, their enol acetates, and ketoximes. In most cases, enzyme-metal combination catalysis has provided good yields and high optical purities.     

Dynamic changes in blood immune cell composition and function in Holstein and Jersey steers in response to heat stress

Heat stress has detrimental effects on livestock via diverse immune and physiological changes; heat-stressed animals are rendered susceptible to diverse diseases. However, there is relatively little information available regarding the altered immune responses of domestic animals in heat stress environments, particularly in cattle steers. This study aimed to determine the changes in the immune responses of Holstein and Jersey steers under heat stress. We assessed blood immune cells and their functions in the steers of two breeds under normal and heat stress conditions and found that immune cell proportions and functions were altered in response to different environmental conditions. Heat stress notably reduced the proportions of CD21⁺MHCII⁺ B cell populations in both breeds. We also observed breed-specific differences. Under heat stress, in Holstein steers, the expression of myeloperoxidase was reduced in the polymorphonuclear cells, whereas heat stress reduced the WC1⁺ γδ T cell populations in Jersey steers. Breed-specific changes were also detected based on gene expression. In response to heat stress, the expression of IL-10 and IL-17A increased in Holstein steers alone, whereas that of IL-6 increased in Jersey steers. Moreover, the mRNA expression pattern of heat shock protein genes such as Hsp70 and Hsp90 was significantly increased in only Holstein steers. Collectively, these results indicate that altered blood immunological profiles may provide a potential explanation for the enhanced susceptibility of heat-stressed steers to disease. The findings of this study provide important information that will contribute to developing new strategies to alleviate the detrimental effects of heat stress on steers.     

A Robust Test for Two‐Stage Design in Genome‐Wide Association Studies

Summary A two‐stage design is cost‐effective for genome‐wide association studies (GWAS) testing hundreds of thousands of single nucleotide polymorphisms (SNPs). In this design, each SNP is genotyped in stage 1 using a fraction of case–control samples. Top‐ranked SNPs are selected and genotyped in stage 2 using additional samples. A joint analysis, combining statistics from both stages, is applied in the second stage. Follow‐up studies can be regarded as a two‐stage design. Once some potential SNPs are identified, independent samples are further genotyped and analyzed separately or jointly with previous data to confirm the findings. When the underlying genetic model is known, an asymptotically optimal trend test (TT) can be used at each analysis. In practice, however, genetic models for SNPs with true associations are usually unknown. In this case, the existing methods for analysis of the two‐stage design and follow‐up studies are not robust across different genetic models. We propose a simple robust procedure with genetic model selection to the two‐stage GWAS. Our results show that, if the optimal TT has about 80% power when the genetic model is known, then the existing methods for analysis of the two‐stage design have minimum powers about 20% across the four common genetic models (when the true model is unknown), while our robust procedure has minimum powers about 70% across the same genetic models. The results can be also applied to follow‐up and replication studies with a joint analysis.