Synergistic roles of leaf boron and calcium during the growing season in affecting sugar and starch accumulation in ripening apple fruit

Fruit sugar content is one of the most important flavor quality traits in the fresh market. Minerals, such as boron (B) and calcium (Ca), are associated with fruit sugar and starch accumulation in many plant species. To better understand the roles of B and Ca in affecting sugar and starch accumulation in apples, 2 g L^?1 Na₂B₄O₇·10H₂O or 10 g L^?1 CaCl₂ was supplied by foliar spray to 20-year-old ‘Fuji’ (Malus domestica Borkh. cv. Fuji) trees at four developmental stages (fruit set, onset of rapid fruit growth, rapid fruit growth and the end of rapid fruit growth), in 2010–2011. The most effective treatment significantly increasing soluble sugar and starch levels in ripening fruit was the foliar application of 2 g L^?1 Na₂B₄O₇·10H₂O during rapid fruit growth, and the robustness of the effects was confirmed for two cultivars, ‘Fuji’ and ‘Orin’, at three orchards in 2011. Foliar applications of B during the onset of rapid fruit growth and rapid fruit growth, as well as the foliar application of Ca at fruit set, significantly increased the soluble sugar content in ripening fruit. In addition, the B application was effective in increasing the fruit starch content, but Ca was not. Both B and Ca treatments significantly increased the leaf concentrations of the other element at least transiently. However, B and Ca effects on fruit sugar/starch did not seem to depend on higher leaf B or Ca levels. In conclusion, B and Ca interact in enhancing fruit sugar and starch contents at the fruit ripening stage.     

Biomass accumulation and partitioning, photosynthesis, and photosynthetic induction in field-grown maize (Zea mays L.) under low- and high-nitrogen conditions

The objectives of this comparative study were to investigate the responses of biomass accumulation and partitioning to nitrogen supply and to examine the effect of low-nitrogen supply on the photosynthetic responses of maize leaves to steady-state and dynamic light. While the difference in leaf number and stem diameter was not statistically significant, there was a significant difference in plant height between the low-nitrogen and high-nitrogen maize plants. During grain-filling period, the ear leaf of the low-nitrogen maize plants possessed lower values of maximum photosynthetic rate, maximum stomatal conductance, maximum transpiration rate, apparent quantum yield, light compensate point, and carboxylation efficiency than did that of the high-nitrogen maize plants. Contrarily, lower values of intercellular CO₂ concentration and dark respiration rate were observed in the high-nitrogen maize plants. In addition, a slower response to simulated sunflecks was found in the ear leaf of the low-nitrogen maize plants; however, stomatal limitations did not operate in the ear leaf of the high-nitrogen or low-nitrogen maize plants during the photosynthetic induction. As compared to the high-nitrogen maize plants, the low-nitrogen maize plants accumulated much less plant biomass but allocated a greater proportion of biomass to belowground parts. In conclusion, our results suggested that steady-state photosynthetic capacity is restricted by both biochemical and stomatal limitation and the photosynthetic induction is constrained by biochemical limitation alone in low-nitrogen maize plants, and that maize crops respond to low-nitrogen supply in a manner by which more biomass was allocated preferentially to root tissues.     

Protective Effects of Mangiferin in Subchronic Developmental Lead-Exposed Rats

Lead is a ubiquitous environmental and industrial pollutant. Exposure to excessive amounts of lead is especially harmful to the central nervous systems of infants and young children, and oxidative stress has been reported as a major mechanism of lead-induced toxicity. To evaluate the ameliorative potential of antioxidant mangiferin (MGN) on lead-induced toxicity, Morris water maze test, determination of blood and bone lead concentration, determination of antioxidant status in plasma, as well as observation of ultrastructural changes in the hippocampus were carried out. In the present study, under a transmission electron microscope, ameliorated morphological damages in the hippocampus were observed in MGN-treated groups. Blood and bone lead concentration in MGN-treated groups lowered to some extent (p?<?0.05, p?<?0.01). The activities of antioxidant enzymes, glutathione (GSH) content, and the GSH/oxidized glutathione ratio in MGN-treated groups were increased, respectively. Further studies are needed to establish whether the observed differences were a direct cause of mangiferin on lead-induced toxicity or not. This study might provide clues for the treatment of lead-induced toxicity.     

Liquid chromatography tandem mass spectrometry in study of the pharmacokinetics of six steroidal saponins in rats

A rapid, simple and sensitive high-performance liquid chromatography tandem mass spectrometry method was developed and validated for simultaneous determination of six main steroidal saponins in Paris polyphylla in rat plasma. Ginsenoside Rg3 was selected as the internal standard (IS). Plasma samples were pretreated with protein precipitation, and the separation was achieved on a reverse phase Agilent poroshell120 EC-C18 column using a gradient mobile phase system of acetonitrile–water containing 0.1% formic acid. The triple quadruple mass spectrometer was set in negative electrospray ionization mode and multiple reaction monitoring (MRM) was used for six steroidal saponins quantification. The precursors to produce ion transitions monitored for polyphyllin I, polyphyllin II, polyphyllin VI, polyphyllin VII, dioscin, gracillin and IS were m/z 899.5 > 853.4, 1059.5 > 1013.5, 783.4 > 737.4, 1075.5 > 1029.5, 913.5 > 867.4, 929.5 > 883.4 and 819.5 > 783.4, respectively. The intra- and inter-day precisions (RSD%) were less than 13% and the average extraction recoveries ranged from 85% to 97.0% for each analyte. Six steroidal saponins were proved to be stable during sample storage, preparation and analytical procedures. The established method was employed for simultaneous quantification and successfully used for the first time for the pharmacokinetics evaluation of the six main compounds after intragastric administration of P. polyphylla extract in Sprague–Dawley rats.     

Cloning and Expression of Genes Encoding F107-C and K88-1NT Fimbrial Proteins of Enterotoxigenic Escherichia coli from Piglets

We cloned two genes coding F107-C and K88-1NT fimbrial subunits from strains E. coli C and 1NT isolated from Thua Thien Hue province, Vietnam. The mature peptide of faeG gene from strain E. coli 1NT (called faeG-1NT) is 100 % similarity with faeG gene, while the CDS of fedA gene from strain C (called fedA-C) has a similarity of 97 % with the fedA gene. Expression of the faeG-1NT and fedA-C genes in E. coli BL21 Star™ (DE3) produced proteins of ~31 and 22 kDa, respectively. The effect of IPTG concentration on the K88-1NT and F107-C fimbriae production was investigated. The results showed that 0.5 mM IPTG is suitable for higher expression of K88-1NT subunit, while 0.75 mM IPTG strongly stimulated expression of F107-C subunit. The optimal induction time for expression was also examined. Generally, highest expression of K88-1NT subunit occurred after 6 h of induction, while that of F107-C subunit is after 14 h.     

Over-expression of l-galactono-γ-lactone dehydrogenase increases vitamin C, total phenolics and antioxidant activity in lettuce through bio-fortification

Epidemiological studies have shown that regular consumption of fruits and vegetables is associated with reduced risk of chronic diseases. Vegetables can provide vitamins, phenolics, flavonoids, minerals and dietary fibers for optimal health benefits. However, some nutrients contained in many fruits and vegetables cannot meet of the complete nutrition need in the human body. Biotechnology has the potential to improve the nutritional value of crops. Considering the high consumption of romaine lettuce in human diet worldwide, the objective of study is to enhance the contents of vitamin C, phenolics and antioxidant activity in lettuce leaves by genetic engineering techniques. The gene expression level, vitamin C content, total phenolics, as well as total and cellular antioxidant activities were analyzed by real-time PCR, HPLC, Folin–Ciocalteu, Hydro-PSC and CAA methods, respectively. The bio-fortification of genetically engineered lettuce increased vitamin C up to 48.94 ± 1.34 mg/100 g FW following the increased over-expression of _At GLDH. This is almost a 3.2-fold increase as the content when compared with wild type lettuce (p < 0.05). In addition, phenolic compounds in transgenic lettuce contained 120.4 ± 1.62 mg GA equiv./100 g FW, almost double the phenolic content of the wild type. Total antioxidant activities were 735.4 ± 47.7 μmol vitamin C equiv./100 g FW, cellular antioxidant activities were 7.33 ± 0.86 μmol quercetin equiv./100 g FW (PBS wash) and 18.14 ± 0.68 μmol quercetin equiv./100 g FW (No PBS wash) in transgenic lettuce, respectively, 1.5, 4 and twofold increases when compared with the wild type. This study suggests that bio-fortification by genetic engineering has great potential to improve vitamin C, phenolic contents and antioxidant activity in lettuce.     

Endogenous hormone profiles during early seed development of C. arietinum and C. anatolicum

Cicer anatolicum, a perennial species, has ascochyta blight resistance superior to that found in the cultivated chickpea. However, hybridization barriers during early stages of embryo development curtail access to this trait. Since hormones play an essential role in early embryo development, we have determined the hormone profiles of 4-, 8-, and 12-day old seeds from a Canadian chickpea (Cicer arietinum L.) cv. CDC Xena, from Indian cvs. Swetha and Bharati, and from a perennial accession of C. anatolicum (PI 383626). Indole-3-acetic acid content peaked on day 4 in CDC Xena, on day 8 in both Indian cultivars but only on day 12 in C. anatolicum. The cytokinins, isopentenyladenosine (iPA) and trans zeatin riboside (tZR) were predominant in CDC Xena and Swetha seeds on day 4, whereas cis zeatin riboside was the major component in Bharati. In C. anatolicum, iPA maxed out on day 4 and tZR on day 12. The bioactive gibberellin GA₁ spiked on day 4 in CDC Xena and Bharati, on day 8 in Swetha but only on day 12 in C. anatolicum. Eight-day old seeds had the highest abscisic acid content in the cultivars but spiked on day 12 in the perennial species. The hormone profiles of the perennial species showed delayed spikes in all four hormone groups indicating that there is a mismatch in the hormone requirements of the different embryos. Improving synchronization of early seed hormone profiles of cultivated and perennial chickpea should improve interspecific hybrid production.     

Partitioning of oxygen uptake and cost of surfacing during swimming in the air-breathing catfish Pangasianodon hypophthalmus

Though air-breathing has probably evolved mainly as a response to hypoxia, it may provide an important oxygen supplement when metabolism is elevated, as for example during swimming. Due to the increased travelling distance involved when an air-breathing fish swims to and from the surface, and the increased drag when the surface is breached, it can be proposed that air-breathing results in a rise in the apparent cost of transport. In order to investigate this hypothesis, it is necessary to use a fish that is able to swim equally well with and without access to air. The striped catfish Pangasianodon hypophthalmus has been shown to have a sufficiently high capacity for aquatic oxygen uptake in normoxia, to allow for such a comparison. Here, we measured the partitioning of oxygen uptake ( $ \dot{M}{\text{O}}_{2} $ ) during swimming and recovery, and calculated the apparent cost of transport with and without access to air, under normoxic conditions. Aerial $ \dot{M}{\text{O}}_{2} $ constituted 25–40 % of the total $ \dot{M}{\text{O}}_{2} $ during swimming and less than 15 % during recovery. The net cost of transport was 25 % lower in fish that did not air-breathe compared to fish that did, showing that the cost of surfacing can be substantial. This is the first study to measure partitioning in an air-breathing fish during swimming at velocities close to the critical swimming speed.     

PEGylated human catalase elicits potent therapeutic effects on H1N1 influenza-induced pneumonia in mice

Therapeutic recombinant human catalase (rhCAT) can quench infection-induced reactive oxygen species (ROS), thereby alleviating the associated tissue damage. Although the intranasal route is efficient to deliver native rhCAT to the lung, the therapeutic effect is limited by rapid elimination from the blood. In this study, we modified rhCAT with the active polymer, polyethylene glycol monomethyl ether (PEG)-5000, and analyzed the pharmacokinetics of PEGylated rhCAT in mice. The high tetra-PEGylation ratio was about 60 %, and PEGylation prolonged the half-life of rhCAT in serum (75 vs. 13.5 min for native rhCAT). The protective effects of PEG-rhCAT were investigated in a mouse model of influenza virus A (H1N1)-associated pneumonia. PEG-rhCAT was more effectively delivered than native rhCAT and was associated with higher survival ratio, less extensive lung injuries, reduced ROS levels, and lower viral replication. Collectively, these findings indicate that PEGylation can enhance the therapeutic efficacy of native rhCAT and suggest that PEGylated rhCAT may represent a novel complement therapy for H1N1 influenza-induced pneumonia.