Biochemical and agro-biological diversity of <Emphasis Type=Italic>Viburnum opulus</Emphasis> genotypes

Interest in the biochemical composition of Viburnum opulus fruit has intensified due to the food industry’s demand for natural vitamins, pigments and other substances that enhance the value of different foods. The present study was conducted to determine the agro-biological and biochemical variability of V. opulus and to select the genotypes that could best serve as sources of health promoting substances. Twelve selected genotypes were evaluated. ‘Leningradskaya Otbornaya’, V. opulus var. americanum, ‘Zarnitsa’, and local clone P2 were determined to be the best genotypes for growth in commercial plantations. Fruits of the local clone P3 were characterised by large amounts of total phenolics, ascorbic acid, and reducing sugars. V. opulus var. sargentii and V. opulus var. americanum contained exceptionally large amounts of total phenolics, 1460.0 and 1400.0 mg/100 g, respectively. The amount of ascorbic acid varied from 12.4 to 41.4 mg/100 g, the amount of carotenoids varied from 1.4 to 2.8 mg/100 g, the amount of anthocyanins varied from 23.2 to 44.6 mg/100 g, and the amount of total phenolics varied from 753.0 to 1460.0 mg/100 g. The presence of these large amounts of biologically active compounds enables their use as potent antioxidants. The data describing agro-biological characteristics, biochemical components, and health promoting activities of V. opulus fruits will increase the understanding of this plant and facilitate its use in the food and pharmaceuticals industry.     

Effects of Chromium(III) Picolinate on Cortisol and DHEAs Secretion in H295R Human Adrenocortical Cells

Dietary chromium(III) picolinate (CrPic) effects on circulating steroid hormones have been reported in various experimental animals. However, direct effects of CrPic on adrenocortical steroidogenesis are uncertain. Therefore, the objective was to determine the effects of CrPic on cortisol and dehydroepiandrosterone sulfate (DHEAs) secretion from H295R cells. In experiment 1, a 24-h exposure to CrPic (0 to 200 μM) had both linear (p < 0.001) and quadratic (p < 0.001) effects on cortisol secretion from forskolin-stimulated cells with the highest cortisol secretion at 0.1 μM of CrPic and the lowest at 200 μM of CrPic. In experiment 2, a 48-h exposure to CrPic (200 μM) decreased cortisol (p < 0.07) release from forskolin-stimulated cells during a 24-h collection period. In experiment 3, a 48-h exposure to CrPic (100 μM) decreased cortisol (p < 0.05) and DHEAs (p < 0.01) from forskolin-stimulated cells during a 24-h sampling period. In experiment 4, a 24-h exposure to forskolin followed by a 24-h exposure to both forskolin and CrPic (100 and 200 μM) decreased both cortisol and DHEAs secretion (p < 0.01). This study suggests that at high concentrations, CrPic inhibits aspects of steroidogenesis in agonist-stimulated adrenocortical cells.     

Probiotic lactic acid bacterium from <Emphasis Type=Italic>kanjika</Emphasis> as a potential source of vitamin B<Subscript>12</Subscript>: evidence from LC-MS,immunological and microbiological techniques

Vitamin B₁₂ was produced by probiotic Lactobacillus plantarum in submerged fermentation (96 h) with successive anaerobic and aerobic phases of 48 h each to give 13 ng vitamin B₁₂/g dry biomass. Sodium cyanide-mediated cell lysis, followed by benzyl alcohol/chloroform/water extraction, improved the release of intracellular vitamin B₁₂ for analysis. The presence of the K⁺ adduct of cyanocobalamin (m/z of 1394) was established using electron spray ionization–mass spectra; growth of a mutant of Escherichia coli in the presence of cyanocobalamin ascertained its bioavailability.     

Plasmacytoid dendritic cells in antiviral immunity and autoimmunity

Plasmacytoid dendritic cells (pDCs) represent a unique and crucial immune cell population capable of producing large amounts of type I interferons (IFNs) in response to viral infection. The function of pDCs as the professional type I IFN-producing cells is linked to their selective expression of Toll-like receptor 7 (TLR7) and TLR9, which sense viral nucleic acids within the endosomal compartments. Type I IFNs produced by pDCs not only directly inhibit viral replication but also play an essential role in linking the innate and adaptive immune system. The aberrant activation of pDCs by self nucleic acids through TLR signaling and the ongoing production of type I IFNs do occur in some autoimmune diseases. Therefore, pDC may serve as an attractive target for therapeutic manipulations of the immune system to treat viral infectious diseases and autoimmune diseases.     

水肥耦合对玉米籽粒全氮含量的影响

采用四因素五水平(1/2实施)二次通用旋转组合设计,选取灌水、施氮肥、施磷肥和秸秆覆盖四因素作为试验因素,在辽西半干旱区褐土农田进行了水肥耦合效应长期定位试验。按照二次通用旋转组合设计统计分析方法建立回归模型,分析了水肥耦合对玉米籽粒全氮含量的影响。结果表明:水肥单因子对籽粒全氮的含量有较明显的影响,影响顺序为施氮秸秆覆盖施磷灌水;当灌水量为700m3.hm-2、施氮量为180kg.hm-2、施磷量为120kg.hm-2和秸秆覆盖量为7500kg.hm-2时,它们每个因素对玉米籽粒全氮含量的影响都集中11.7g·kg-1,此时籽粒蛋白质含量为73g·kg-1,产量为12000kg.hm-2,表明该处理组合下,玉米的经济效益和生态效益达到最佳,推荐生产上以此进行施肥。     

壳聚糖的化学改性及其在生物医药领域的应用进展

本文综述了近年来壳聚糖的酰化、羧甲基化、接枝、烷基化和交联等化学改性方法及其在生物医用高分子方面的应用进展,总结了壳聚糖改性及其应用过程中存在的问题并对其发展趋势作了预测。     

Pol32 is required for Pol zeta-dependent translesion synthesis and prevents double-strand breaks at the replication fork

POL32 encodes a non-essential subunit of Polδ and plays a role in Polδ processivity and DNA repair. In order to understand how Pol32 is involved in these processes, we performed extensive genetic analysis and demonstrated that POL32 is required for Polζ-mediated translesion synthesis, but not for Polη-mediated activity. Unlike Polζ, inactivation of Pol32 does not result in decreased spontaneous mutagenesis, nor does it limit genome instability in the absence of the error-free postreplication repair pathway. In contrast, inactivation of Pol32 results in an increased rate of replication slippage and recombination. A genome-wide synthetic lethal screen revealed that in the absence of Pol32, homologous recombination repair and cell cycle checkpoints play crucial roles in maintaining cell survival and growth. These results are consistent with a model in which Pol32 functions as a coupling factor to facilitate a switch from replication to translesion synthesis when Polδ encounters replication-blocking lesions. When Pol32 is absent, the S-phase checkpoint complex Mrc1–Tof1 becomes crucial to stabilize the stalled replication fork and recruit Top3 and Sgs1. Lack of any of the above activities will cause double strand breaks at or near the replication fork that require recombination as well as Rad9 for cell survival.     

Chloroplast envelope membranes: a dynamic interface between plastids and the cytosol

Chloroplasts are bounded by a pair of outer membranes, the envelope, that is the only permanent membrane structure of the different types of plastids. Chloroplasts have had a long and complex evolutionary past and integration of the envelope membranes in cellular functions is the result of this evolution. Plastid envelope membranes contain a wide diversity of lipids and terpenoid compounds serving numerous biochemical functions and the flexibility of their biosynthetic pathways allow plants to adapt to fluctuating environmental conditions (for instance phosphate deprivation). A large body of knowledge has been generated by proteomic studies targeted to envelope membranes, thus revealing an unexpected complexity of this membrane system. For instance, new transport systems for metabolites and ions have been identified in envelope membranes and new routes for the import of chloroplast-specific proteins have been identified. The picture emerging from our present understanding of plastid envelope membranes is that of a key player in plastid biogenesis and the co-ordinated gene expression of plastid-specific protein (owing to chlorophyll precursors), of a major hub for integration of metabolic and ionic networks in cell metabolism, of a flexible system that can divide, produce dynamic extensions and interact with other cell constituents. Envelope membranes are indeed one of the most complex and dynamic system within a plant cell. In this review, we present an overview of envelope constituents together with recent insights into the major functions fulfilled by envelope membranes and their dynamics within plant cells. Special Issue of Photosynthesis Research in honor of Andrew A. Benson.     

Temporal and spatial trends in nitrogen and phosphorus inputs to the watershed of the Altamaha River,Georgia, USA

The watershed of the Altamaha River, Georgia, is one of the largest in the southeastern U.S., draining 36,718 km² (including parts of metro Atlanta). We calculated both nitrogen (fertilizer, net food and feed import, atmospheric deposition, and biological N fixation in agricultural and forest lands) and phosphorus (fertilizer and net food and feed import) inputs to the watershed for 6 time points between 1954 and 2002. Total nitrogen inputs rose from 1,952 kg N km⁻² yr⁻¹ in 1954 to a peak of 3,593 kg N km⁻² yr⁻¹ in 1982 and then declined to 2,582 kg N km⁻² yr⁻¹ by 2002. Phosphorus inputs rose from 409 kg P km⁻² yr⁻¹ in 1954 to 532 kg P km⁻² yr⁻¹ in 1974 before declining to 412 kg P km⁻² yr⁻¹ in 2002. Fertilizer tended to be the most important input of both N and P to the watershed, although net food and feed import increased in importance over time and was the dominant source of N input by 2002. When considered on an individual basis, fertilizer input tended to be highest in the middle portions of the watershed (Little and Lower Ocmulgee and Lower Oconee sub-watersheds) whereas net food and feed imports were highest in the upper reaches (Upper Oconee and Upper Ocmulgee sub-watersheds). Although the overall trend in recent years has been towards decreases in both N and P inputs, these trends may be offset due to continuing increases in animal and human populations.     

Removal of agricultural non-point source pollutants by ditch wetlands: implications for lake eutrophication control

Ditches grown with nature reed (Phragmites communis Trin) and wild rice (Zizania latifolia Turcz) were selected to study the removal capacity of agricultural non-point source pollutants so as to find a way to alleviate eutrophication in Lake Taihu. Ditches sediment from depths below 40 cm can accumulate organic matter and total nitrogen (TN). TN is correlated positively to organic matter in reed populated sediment and wild rice populated sediment. This suggests that the main composition of TN is organic nitrogen derived from plant decomposition. A significant negative relationship between TN and pH was found in reed and wild rice sediments. Seasonal harvest of helophyte vegetation is an effective method to remove N and P from wetlands. Organic matter and TN concentrations in water and sediments (0–20 cm) in areas where reeds were removed are lower than non-harvested areas (control). Reeds and wild rice have high uptake ability of nitrogen (N) and phosphorus (P). However, the low economic value of these plants will not stimulate voluntary harvest of farmers. Zizania caduciflora Turez Hand-mazt is a kind of vegetable widely cultivated in ditches around the lake. It can also absorb N and P effectively. Thus, large scale cultivation of Z. caduciflora to replace nature plants may improve water quality.