磁场对大鼠血清营养相关生化指标的影响

报道了旋转恒定磁场对大鼠血液生化指标的影响.在强度为0 4T,旋转速率为8Hz的磁场条件下,鼠龄3周的大鼠,磁场每天处理2h,共持续10周,导致血清葡萄糖水平显著下降;鼠龄为10周的大鼠,每天磁场处理2h,共持续4周,则引起血清甘油三酯水平的显著降低,血清高密度脂蛋白水平则显著上升.     

Effects of monensin on glucose metabolism in transition dairy cows

Eight multiparous periparturient Holstein cows fitted with ruminal cannula were used in a split plot design to evaluate the effects of monensin on plasma glucose metabolism. Diets were top-dressed daily with 0 mg/cow of monensin (control) or 300 mg/cow of monensin (MON) both pre- and postpartum. Plasma glucose kinetic parameters on d ?13 ± 2.0 and 19 ± 1.6 relative to parturition were determined by using stable isotopes. Na-1-¹³C₃-Propionate (labeled propionate) was infused into the rumen to measure glucose synthesis originating from ruminal propionate, and U-¹³C-glucose (labeled glucose) was injected into the jugular vein to determine total glucose kinetics. A sampling period of 480 min following labeled glucose injection was implemented. A compartmental analysis was employed to determine steady state glucose kinetic parameters. To develop a steady state glucose model, the Windows version of SAAM software (WinSAAM) was used. A 4-compartment model was adequate to comprehensively describe plasma glucose metabolism. The main model compartments consisted of propionate and plasma glucose. The time frame of the 480-min sampling period post-tracer glucose infusion allowed accurate quantification of glucose metabolism. The model estimated that glucose input from sources other than ruminal propionate decreased with MON, from 2.26 to 1.09 g/min postpartum. Gluconeogenesis, expressed as the propionate contribution to the plasma glucose pool, increased in cows fed MON (22 vs. 31%), whereas glucose oxidation, expressed as the glucose disposal rate, significantly decreased (1.67 vs. 0.92 g/min). In conclusion, MON may improve the energy status of transition cows by (1) improving the efficiency of propionate to produce glucose and (2) decreasing glucose oxidation in body tissues.     

Pheromone responsiveness is regulated by components of the Gpr1p‐mediated glucose sensing pathway in Saccharomyces cerevisiae

Many fungi have evolved mechanisms to assess environmental nutrient availability prior to the energy‐intensive process of mating. In this study, we examined one such system in Saccharomyces cerevisiae, involving a glucose‐sensing pathway mediated by Gpr1p and the pheromone‐induced mating pathway. Initially we observed that the mating pathway in MATa cells is sensitive to environmental glucose depletion. This phenomenon can be partially reversed with a high glucose spike, but not with the addition of low levels of glucose. Deletion of the low‐affinity glucose receptor, Gpr1p, eliminated this glucose‐induced recovery of pheromone responsiveness. We then determined the impact of GPR1 deletion on the mating pathway and observed that, in all end points studied, the mating pathway response to pheromone is reduced in the absence of Gpr1p. Similarly, elimination of the Gα for Gpr1p, Gpa2p, resulted in reduction in pheromone sensitivity in all assays studied. The negative effect of removing Gpr1p on mating pathway activation could be recovered by overexpressing the mating receptor, Ste2p. Furthermore, Ste2p levels are reduced in the absence of glucose and GPR1. These data suggest that activity of the GPCR‐mediated mating pathway in S. cerevisiae is modulated by extracellular glucose concentrations through the only other GPCR in MATa cells, Gpr1p. Copyright © 2014 John Wiley & Sons, Ltd.     

Conversion efficiency of glucose/xylose mixtures for ethanol production using Saccharomyces cerevisiae ITV01 and Pichia stipitis NRRL Y‐7124

BACKGROUND: Efficient conversion of glucose/xylose mixtures from lignocellulose is necessary for commercially viable ethanol production. Oxygen and carbon sources are of paramount importance for ethanol yield. The aim of this work was to evaluate different glucose/xylose mixtures for ethanol production using S. cerevisiae ITV‐01 (wild type yeast) and P. stipitis NRRL Y‐7124 and the effect of supplying oxygen in separate and co‐culture processes. RESULTS: The complete conversion of a glucose/xylose mixture (75/30 g L^?1) was obtained using P. stipitis NRRL Y‐7124 under aerobic conditions (0.6 vvm), the highest yield production being Y_p/s = 0.46 g g^?1, volumetric ethanol productivity Q_pmax = 0.24 g L^?1 h^?1 and maximum ethanol concentration P_max = 34.5 g L^?1. In the co‐culture process and under aerobic conditions, incomplete conversion of glucose/xylose mixture was observed (20.4% residual xylose), with a maximum ethanol production of 30.3 g L^?1, ethanol yield of 0.4 g g^?1 and Q_pmax = 1.26 g L^?1 h^?1. CONCLUSIONS: The oxygen present in the glucose/xylose mixture promotes complete sugar consumption by P. stipitis NRRL Y‐7124 resulting in ethanol production. However, in co‐culture with S. cerevisiae ITV‐01 under aerobic conditions, incomplete fermentation occurs that could be caused by oxygen limitation and ethanol inhibition by P. stipitis NRRL Y‐7124; nevertheless the volumetric ethanol productivity increases fivefold compared with separate culture. Copyright © 2011 Society of Chemical Industry     

Influences of pretreatment and drying methods on composition,micro/molecular structures and some health‐related functional characteristics of dietary fibre powder from orange pulp residues

Influences of pretreatment methods (washing, blanching, soaking in ethanol), drying methods (hot air‐drying, infrared‐drying, microwave‐drying) and drying temperature on selected characteristics of dietary fibre powder from orange pulp residues were investigated. Pretreatments improved the hydration properties, oil‐holding capacity and glucose dialysis retardation index, but led to losses of fibres, decreased α‐amylase inhibitory activity and aflatoxin B₁ adsorption capacity. Hydration properties, oil‐holding capacity and glucose uptake depended on the structure and porosity of the fibre, while the ability to inhibit α‐amylase and AFB₁ adsorption depended more on the content and molecular fingerprinting of the fibre. Drying condition did not significantly affect functional properties of the fibre, except for the ability to uptake glucose, inhibit α‐amylase and adsorb AFB₁ (P ≤ 0.05). Hot air‐drying at 60 °C resulted in fibre with the highest ability to decrease the rate of glucose and AFB₁ adsorption.     

保加利亚乳杆菌生长性能与后酸化的关系初探

以5株德氏乳杆菌保加利亚亚种为出发菌株,详细研究了5株菌的生长代谢、酸敏感性及蛋白水解力,并分析了这些特性与后酸化之间的关系。结果表明:5株菌的生长性能与后酸化之间存在紧密联系。其中,菌株的生长速度和糖分解代谢能力与后酸化成正比;对酸较敏感菌株的后酸化也较弱;菌株的蛋白水解能力与生长速度和后酸化之间没有明显的相关性。     

Modelling concentration gradients in fed-batch cultivations of E. coli – towards the flexible design of scale-down experiments

The cover image is based on the Research Article Modelling concentration gradients in fed-batch cultivations of E. coli - towards the flexible design of scale-down experiments by Emmanuel Anane et al., DOI: 10.1002/jctb.5798 .