Synthesis of theaflavin from epicatechin and epigallocatechin by plant homogenates and role of epicatechin quinone in the synthesis and degradation of theaflavin

Oxidation products of (-)-epicatechin and (-)-epigallocatechin by treatment with homogenates of 62 plants belonging to 49 families were compared. Forty-six plants were capable of synthesizing theaflavin, a black tea pigment, regardless of whether they contained catechins. Loquat, Japanese pear, and blueberry had activities higher than that of fresh tea leaves after 5 h of treatment; furthermore, these plants oxidized theaflavin to theanaphthoquinone. An additional new metabolite, dehydrotheasinensin, was generated on treatment with fresh tea leaves, eggplant, and unripened Japanese orange. Evidence for the oxidation of epigallocatechin and theaflavin by electron transfer to epicatechin quinone was demonstrated in a time course study using bananas and trapping the quinone intermediates as glutathione conjugates.     

Regulation of CD8+ T cell development by thymus-specific proteasomes

Proteasomes are responsible for generating peptides presented by the class I major histocompatibility complex (MHC) molecules of the immune system. Here, we report the identification of a previously unrecognized catalytic subunit called beta5t. beta5t is expressed exclusively in cortical thymic epithelial cells, which are responsible for the positive selection of developing thymocytes. Although the chymotrypsin-like activity of proteasomes is considered to be important for the production of peptides with high affinities for MHC class I clefts, incorporation of beta5t into proteasomes in place of beta5 or beta5i selectively reduces this activity. We also found that beta5t-deficient mice displayed defective development of CD8(+) T cells in the thymus. Our results suggest a key role for beta5t in generating the MHC class I-restricted CD8(+) T cell repertoire during thymic selection.     

PLANETARY SCIENCE: Fountains of Youth

The search for geologic features indicative of past or present water is central to Mars exploration programs. As Tanaka explains in his Perspective, such features have tended to be associated with very old (> 1 billion years) regions. However, a study by Malin and Edgett indicates that the youngest geologic features on Mars show signs of fluid discharge and runoff. If the results hold up, then some very unusual event must have occurred in the recent past on Mars.     

Mode of action of novel 2-(benzylamino)-4-methyl-6-(trifluoro- methyl)-1,3,5-triazine herbicides: inhibition of photosynthetic electron transport and binding studies.

Novel 2-(benzylamino)-4-methyl-6-(trifluoromethyl)-1,3,5-triazines have the same 1,3,5-triazine skeleton as atrazine, although some of them, for example, 2-(3-chlorobenzylamino)-4-methyl-6-(trifluoromethyl)-1,3,5-tria zin e [pI(50)(spinach) = 7.21], show a >3 times stronger photosynthetic electron transport inhibitory activity than atrazine [pI(50)(spinach) = 6.72]. The new triazines have only one amino group at the triazine ring, and their molecular shapes are different from atrazine. The replacement of the bound [(14)C]atrazine by 1,3,5-triazines was tested to determine whether the novel 1,3,5-triazine analogues exhibit the same binding pattern at the D1-protein as atrazine. It was found that [(14)C]atrazine bound to the D1-protein was replaced by the triazine tested by a clearly competitive interaction. Obviously, the novel 1,3,5-triazines are attached to the same binding niche as atrazine.     

Structure of polymeric polyphenols of cinnamon bark deduced from condensation products of cinnamaldehyde with catechin and procyanidins

Structures of two condensation products obtained by the reaction of cinnamaldehyde with (+)-catechin were determined by spectroscopic methods. One had two phenylpropanoid units at the C-6 and C-8 positions of the catechin skeleton. The other product had a dimeric structure with two catechin and two phenylpropanoid units. Matrix-assisted laser desorption time-of-flight mass spectrometric analysis of the reaction products of cinnamaldehyde with procyanidin B1 suggested that procyanidins were oligomerized in a manner similar to the reaction with catechin. Furthermore, (13)C NMR spectral comparison of the condensation products with the polymeric procyanidins obtained from commercial cinnamon bark strongly suggested that the procyanidins in the cinnamon bark also were polymerized by reaction with cinnamaldehyde.     

Seeds of doubt: Re‐assessing the impact of grain P concentrations on seedling vigor

Interest in developing crop varieties with low grain phosphorus (P) in order to minimize the removal of P from fields in harvested grain has been limited due to the view that a low‐P grain trait may impair subsequent seedling vigor. This perception is based on relatively few studies, which typically investigated seedling growth on infertile soils, and used seed that may have differed in attributes other than P concentration. To investigate whether these anomalies cast sufficient doubt to warrant renewed research in this field, we compared the growth of rice seedlings from seed low in P obtained from P‐starved plants (P‐starved seed) vs. high‐P seeds (obtained from P‐fertilized plants) in P‐deficient and P‐replete soils. While plants from high‐P seed were superior in the P‐deficient soil, plants grown from P‐starved seed overcame an initial lull in early vigor to obtain similar biomass at maturity as plants grown from high‐P seed. Subsequent experiments were undertaken using high‐P seed vs. seed low in P from a range of rice genotypes that was not obtained from P‐stressed plants (low‐P seed): There was no reduction in seedling vigor or biomass and grain yields at maturity of plants from low‐P seeds in low‐P soil compared to plants from high‐P seed, though responses were genotype‐specific. The results suggest that multiple factors can confound the results of seed P × seedling vigor studies, and that a renewed research effort to define the minimum P levels in seeds required for adequate seedling growth across a range of environments is warranted.     

Differences in Alcohol‐Soluble Protein from Genetically Altered Wheat Using Capillary Zone Electrophoresis,One‐ and Two‐Dimensional Electrophoresis,and a Novel Gluten Matrix Association Factor Analysis

Wheat protein composition and organization play interrelated roles in determining physical properties for technological purposes. In prior research, a number of isogenic wheat lines of Bobwhite that have high levels of expression of the native Dx5 and/or Dy10 high‐molecular‐weight glutenin subunits (HMW‐GS) were examined vis‐à‐vis physical properties related to separation. In particular, these altered lines were characterized by poor mixing properties, the formation of mixtures in water that could not be separated by conventional mechanical methods, reduced water absorption, unique milling properties, and severely limited development of microscopic fibrils. These attributes suggested inherent organizational differences at submicroscopic and molecular levels among the various lines. Therefore, proteins were fractionated from whole meals using 70% ethanol to elucidate solubility characteristics and compositions and to infer structural properties. Capillary zone electrophoresis and one‐ and two‐dimensional SDS‐PAGE (2DE) revealed striking differences in the protein composition and solubility among these new lines and the Bobwhite from which they were derived. Generally, Bobwhite yielded soluble protein that included not only what would be considered as classical gliadins but also some of each of the HMW‐GS as monomers or polymers with low degrees of polymerization, whereas the genetically altered lines produced far less total soluble protein and very limited amounts of HMW‐GS. In the extreme, high levels of expression of Dx5 subunit not only led to reduced solubility of the HMW‐GS but also limited the solubility of the many other proteins that are normally soluble. In addition, a matrix association factor similar to the classical separation factor of analytical chemistry and chemical engineering was introduced and applied to 2DE data for insoluble and soluble protein to summarize and index relative involvement of specifically enhanced proteins in the insoluble gluten matrix after equilibration with ethanol. The highest relative association was determined for the HMW‐GS lines enriched in Dx5 or Dy10 protein and the lowest for Bobwhite. Greater association was indicated for Dx5 than for Dy10 protein in these lines. The value of the association factor was likely influenced by differences in glutamine‐to‐cysteine ratios and differences in altered glutenin chain configurations stemming from high levels of expression of a single or limited number of HMW‐GS.     

Radioactive cesium distribution in bamboo [Phyllostachys reticulata (Rupr) K. Koch] shoots after the TEPCO Fukushima Daiichi Nuclear Power Plant disaster

Abstract

Radioactivity levels of cesium (Cs)-134 and ¹³⁷Cs in bamboo [Phyllostachys reticulata (Rupr) K. Koch] sprouts grown from April to June 2011 over a wide area (including Fukushima Prefecture) were elevated (max. 3100 Bq kg^?1 fresh weight) after the Tokyo Electric Power Company, Inc. (TEPCO) Fukushima Daiichi Nuclear Power Plant disaster in March 2011. Bamboo sprouts in 2012 also contained high radioactivity levels. Radioactivity imaging analysis of bamboo sprouts harvested in 2012 showed increasing concentration gradients of radioactivity from the lower parts to the top of the sprouts. The peels were individually separated from the sprouts, and the inner edible part (trunk) was cross-sectioned at the internodal sections from the top to the lower parts. Each segmented trunk and its corresponding peel were analyzed for radioactive cesium (¹³⁴Cs and ¹³⁷Cs) and stable cesium (¹³³Cs). The concentrations of ¹³⁴Cs and ¹³⁷Cs showed significant increases from the lower part to the top, whereas ¹³³Cs showed an almost constant value in the trunk and peel except in the peel of the top node. We speculated that ¹³⁴Cs and ¹³⁷Cs in newly emerging bamboo sprouts in 2012 were translocated mainly from various plant tissues (where the fallout was layered on the bamboo tissues) in older bamboo, while ¹³³Cs was translocated from the soil through the roots of the new bamboo sprouts and was present in the roots and stems.     

Effects of ingested turmeric oleoresin on glucose and lipid metabolisms in obese diabetic mice: a DNA microarray study

Turmeric, the rhizome of Curcuma longa L., has a wide range of effects on human health. Turmeric oleoresin, an extract of turmeric, is often used for flavoring and coloring. Curcuminoids and turmeric essential oil are both contained in turmeric oleoresin, and both of these fractions have hypoglycemic effects. In the present study, we comprehensively assessed the effect of turmeric oleoresin on hepatic gene expression in obese diabetic KK-Ay mice using DNA microarray analysis and quantitative real-time polymerase chain reaction (PCR). Female KK-Ay mice aged 6 weeks (n = 6/group) were fed a high-fat diet containing turmeric oleoresin, curcuminoids, and essential oil for 5 weeks. The same diet without any of these fractions was used as a control diet. Ingestion of turmeric oleoresin and essential oil inhibited the development of increased blood glucose and abdominal fat mass, while curcuminoids only inhibited the increase in blood glucose. DNA microarray analysis indicated that turmeric oleoresin ingestion up-regulated the expression of genes related to glycolysis, beta-oxidation, and cholesterol metabolism in the liver of KK-Ay mice, while expression of gluconeogenesis-related genes was down-regulated. Real-time PCR analysis was conducted to assess the contribution of the curcuminoids and essential oil in turmeric oleoresin to the changes in expression of representative genes selected by DNA microarray analysis. This analysis suggested that curcuminoids regulated turmeric oleoresin ingestion-induced expression of glycolysis-related genes and also that curcuminoids and turmeric essential oil acted synergistically to regulate the peroxisomal beta-oxidation-related gene expression induced by turmeric oleoresin ingestion. These changes in gene expression were considered to be the mechanism by which the turmeric oleoresin affected the control of both blood glucose levels and abdominal adipose tissue masses. All of these results suggest that the use of whole turmeric oleoresin is more effective than the use of either curcuminoids or the essential oil alone.     

Effect of CO2-free air treatment on nitrogen fixation of soybeans inoculated with Bradyrhizobium japonicum and Rhizobium fredii

Soybean (Glycine max L. Merr.) cultivars Akisirome and Peking were inoculated with Bradyrhizobium japonicum Is-21 and Rhizobium fredii USDA 194, respectively, and were grown in cylindrical pots containing sterilized vermiculite which were aerated with CO₂-free air or ambient air to study the effects of CO₂ deficiency in the rhizosphere on plant growth, nodulation, and nitrogen fixation. The repressive effects of CO₂-free air treatment were more conspicuous in Peking than Akisirome, and nodule number, nodule mass, amount of biologically fixed N and plant growth of Peking were reduced remarkably by the CO₂-free air treatment.

Acetylene reduction activity (ARA) of Peking inoculated with USDA 194 and Akisirome inoculated Is-21 was assayed in the absence and presence of CO₂, ARA of Akisirome was not affected by the absence of CO₂, while that of Peking decreased drastically.

Based on these results, it was concluded that nitrogen fixation by Akisirome inoculated with B. japonicum Is-21 was not appreciably influenced by CO₂ deficiency in the rhizosphere, while that of Peking inoculated with R. fredii USDA 194 was severely repressed, and the decrease was estimated to be due to both the reduction of the nodule mass and specific nitrogen-fixing activity.