Eco-efficiency of urban material metabolism: a case study in Shenzhen, China

The keys of studying urban sustainable development are material metabolism flux and efficiency. Metabolism flux of urban materials can only reflect the metabolism velocity, while its eco-efficiency can determine the metabolism capacity to support socio-economic development. The general model and the measure model of the eco-efficiency were set up, based on the source recycle (decreasing the consumption of crude resources) and the terminal recycle (decreasing the discharge of pollutants) of production and life. These models were employed to study material metabolism flux and efficiency in Shenzhen, China. Results showed that water, energy and waste metabolism fluxes have increased since 1998 with constant socio-economic development, and their eco-efficiencies have also increased rapidly. When GDP rose by 2.7 times, the metabolism fluxes of urban water and electricity rose by 1.5 and 3.0 times, respectively. When the added value of industry rose by 3.7 times, the metabolism fluxes of industrial water, electricity, energy and waste rose by 1.9, 3.5, 2.7 and 2.0 times, respectively. When population rose by 1.5 times, the metabolism fluxes of residential water and electricity rose by 1.8 and 1.7 times, respectively. During the period, the resource efficiency, environmental efficiency and eco-efficiency rose by 1.8, 3.7 and 2.3 times, respectively. Whereas the efficiency of material metabolism has been improved in Shenzhen, the scarcity of material resources has become more and more serious. Therefore, it is necessary to further improve the efficiency of material metabolism. The keys of improving the eco-efficiency of urban material metabolism are the increasing of resource and environmental efficiencies, and the establishing of the recycling chain of re-utilization of waste resources.     

Comparison of quasisteady-state performance of the DEAMOX process under intermittent and continuous feeding and different nitrogen loading rates

The recently developed denitrifying ammonium oxidation (DEAMOX) process combines the anammox reaction with autotrophic denitrifying conditions using sulfide as an electron donor for the production of nitrite from nitrate within an anaerobic biofilm. This paper compares a quasisteady-state performance of this process for treatment of baker's yeast wastewater under intermittent and continuous feeding and increasing nitrogen loading rate (NLR) from 300 till 858 mg N/L/d. The average total nitrogen removal slightly decreased on increasing the NLR: from 86 to 79% (intermittent feeding) and from 87 to 84% (continuous feeding). The better performance under continuous feeding was due to a more complete nitrate removal in the former case whereas the ammonia removal was similar for both feeding regimes under the comparable NLR. A possible explanation can be that, during continuous feeding (simultaneous supply of nitrate and sulfide), there were less mass transfer limitations for sulfide oxidizing denitrifiers presumably located in the outer layer of sludge aggregates. On the contrary, the ammonia oxidisers presumably located inside the aggregates apparently suffered from nitrite mass transfer limitations under both the feedings. The paper further describes some characteristics of the DEAMOX sludge.     

Effects of acute and chronic protein intake on metabolism, appetite, and ghrelin during weight loss

Objective: This study evaluated the effects of acute and chronic consumption of higher dietary protein on energy expenditure, macronutrient use, appetite, and appetite‐regulating hormones during weight loss in women. Research Methods and Procedures: Thirty‐eight women chronically consuming a 750 kcal/d energy‐deficit diet with a protein content of 30% (higher protein‐chronic diet, HP‐CD, n = 21) or 18% (normal protein‐chronic diet, NP‐CD, n = 17) for 9 weeks were tested. On separate days, metabolic, appetite, and hormonal responses were measured over 4 hours when the women consumed a higher protein‐acute meal (HP‐AM) (30% of energy as protein) or a normal protein‐acute meal (NP‐AM) (18% of energy as protein). Results: With chronic diet groups combined, HP‐AM led to lower respiratory exchange ratio (0.829 ± 0.005 vs. 0.843 ± 0.008; p < 0.05), lower carbohydrate oxidation (p < 0.05), and higher fat oxidation (p < 0.05) compared with NP‐AM. HP‐AM also led to reduced self‐reported postprandial hunger (p < 0.001) and desire to eat (p < 0.001) and lower postprandial ghrelin (252 ± 16 vs. 274 ± 18 ng/mL · 240 minutes, p < 0.05) compared with NP‐AM. No differences in postprandial energy expenditure (PPEE) occurred between meals. When combining acute meals, respiratory exchange ratio was lower (p < 0.05) and protein oxidation (p < 0.001) was higher in the HP‐CD vs. NP‐CD. An acute meal‐by‐chronic diet interaction was observed with PPEE such that HP‐AM led to greater PPEE in the HP‐CD vs. NP‐CD (28.7 ± 2.7 vs. 19.9 ± 2.7 kcal/min for 195 minutes; p < 0.05). Conclusions: During weight loss, thermogenesis and protein use appear to be influenced by chronic protein intake, while appetite and ghrelin are more responsive to acute protein intake.     

1,3-丙二醇发酵中甘油代谢及产物抑制作用

对微生物法甘油转化成1,3-丙二醇过程中代谢规律及代谢控制的相关酶作以简述,并着重分析了丁酸梭菌发酵生产中乙酸、丁酸等副产物对细胞的抑制作用,对未来的研究发展方向进行了展望。     

药用植物刺山柑愈伤组织诱导及细胞生长代谢特征研究

本文研究了不同外植体及激素对刺山柑愈伤组织诱导的影响,不同激素配比对愈伤组织增殖培养以及悬浮细胞的生长与代谢特征。结果表明:以刺山柑叶片作为诱导愈伤组织的材料,效果较佳;愈伤组织诱导和继代的适宜培养条件是分别是MS 0.5mg/L 2,4-D 1.0mg/L6-BA和MS 1.0mg/L2,4-D 1.5mg/L6-BA。刺山柑悬浮培养细胞的生长周期为30天左右,细胞生长曲线呈"S"形,生物量增长2.8倍左右;细胞生长周期内,碳源消耗规律表现为蔗糖和可溶性总糖的浓度持续降低,而还原糖则表现为先升高后降低;过氧化物酶活测定显示酶活水平与蔗糖浓度的高低呈一定程度的正相关。     

家蚕磷酸吡哆醛激酶cDNA的克隆和酶活表征

吡哆醛激酶 (EC 2.7.1.35) 在 ATP 和 Zn2 的存在下,催化吡哆醛的磷酸化反应生成磷酸吡哆醛 (PLP)。在生物体内许多酶促反应中,PLP 是一种重要的辅酶因子。家蚕和哺乳动物一样,需依赖食物中的维生素 B6前体来合成 PLP。文章描述了利用家蚕基因组数据库序列信息及使用 PCR 方法,克隆出编码家蚕吡哆醛激酶的 cDNA (GenBank 登录号:DQ452397)。克隆到的 cDNA 含有一个 894 bp 的完整可读框,编码一条分子量为 33.1 kDa,含 298 个氨基酸残基的蛋白质。序列比对显示此蛋白质序列与人类吡哆醛激酶蛋白序列具有 48.6%的同一性,包含吡哆醛激酶家族共有的特征保守序列,但其氨基酸残基数比哺乳动物和植物克隆到的吡哆醛激酶残基数均少 10 多个残基。多序列比对结果显示,吡哆醛激酶中几个有关键功能且在哺乳动物和植物中均保守的氨基酸残基在此蛋白中被替换为其他种类氨基酸残基。采用 T7 启动子和 T7 聚合酶表达系统对克隆到的 cDNA 进行了原核表达并对表达粗提产物进行了酶活检测。实验结果显示表达得到的可溶性蛋白产物占其总蛋白量为 10%,细胞粗提物具有活力为 30 nmol/min/mg 的吡哆醛激酶活性,结果证实了克隆到的 cDNA 编码家蚕中的吡哆醛激酶。     

Backbone assignment of human proliferating cell nuclear antigen

PCNA is an essential factor for DNA replication, repair, chromatin metabolism, and effector of cell-cycle regulatory signals. The assignment of backbone ¹H_N, ¹³C_α, ¹³CO, and ¹⁵N, and sidechain ¹³C_β resonances of the human PCNA homotrimeric ring (∼90 kDa, 261 residues) is reported here.     

The effects of (22S,23S)-and (22R,23R)-3β-hydroxy-22,23-oxido-5α-ergost-8(14)-en-15-ones on lipid biosynthesis and metabolism of exogenous cholesterol in Hep G2 cells

Novel synthetic oxysterols (22S,23S)-3β-hydroxy-22,23-oxido-5α-ergost-8(14)-en-15-one (I) and (22R,23R)-3β-hydroxy-22,23-oxido-5α-ergost-8(14)-en-15-one (II) efficiently inhibited cholesterol biosynthesis in human hepatoma Hep G2 cells during short-term incubation in a serum free medium (IC₅₀ values of 1.9 ± 0.2 and 0.6 ± 0.2 μ M, respectively). Cultivation of Hep G2 cells in the presence of 5 μM concentration of either (I) or (II) resulted in significant reduction of cholesterol biosynthesis (52% and 57% from control), and also changes in biosynthesis of fatty acids, triglycerides, and cholesteryl esters. Compounds (I) and (II) stimulated transformation of exogenous cholesterol to polar products secreted into the culture medium (156 % and 175% of control) as it that was shown in experiments in Hep G2 cells prelabeled with [³H]cholesterol.     

The biochemistry of drug metabolism--an introduction: Part 2. Redox reactions and their enzymes

This review continues a general presentation of the metabolism of drugs and other xenobiotics started in a recent issue of Chemistry & Biodiversity. This Part 2 presents the numerous oxidoreductases involved, their nomenclature, relevant biochemical properties, catalytic mechanisms, and the very diverse reactions they catalyze. Many medicinally, environmentally, and toxicologically relevant examples are presented and discussed. Cytochromes P450 occupy a majority of the pages of Part 2, but a large number of relevant oxidoreductases are also considered, e.g., flavin-containing monooxygenases, amine oxidases, molybdenum hydroxylases, peroxidases, and the innumerable dehydrogenases/reductases.