Comparative Energy, Environmental, and Economic Analysis of Traditional and E-commerce DVD Rental Networks

This study is a comparative life-cycle assessment (LCA) of two competing digital video disc (DVD) rental networks: the e-commerce option, where the customer orders the movies online, and the traditional business option, where the customer goes to the rental store to rent a movie. The analytical framework proposed is for a customer living in the city of Ann Arbor, Michigan in the United States. The primary energy and environmental performance for both networks are presented using a multicriterion LCA. The package selected by the traditional network is responsible for 67% of the difference in total energy consumption of the two alternatives. Results show that the e-commerce alternative consumed 33% less energy and emitted 40% less CO2 than the traditional option. A set of sensitivity analyses test the influence of distance traveled, transportation mode, and reuse of DVD and DVD packaging on the final results. The mode of transportation used by the customer in the traditional business model also affects global emissions and energy consumption. The customer walking to the store is by far the best option in the traditional network; however, the e-commerce option performed comparatively better despite all transportation modes tested. A novel economic indicator, ESAL, is used to compare different transportation modes based on the level of stress exerted on the pavement. The two networks are compared on the basis of cost accounting; consistent with its energy and environmental advantages, the e-commerce network also exerts lesser economic impact, by $1.17, for the functional unit tested.     

Cancer stem cells in glioblastoma — molecular signaling and therapeutic targeting

Glioblastomas (GBMs) are highly lethal primary brain tumors. Despite current therapeutic advances in other solid cancers, the treatment of these malignant gliomas remains essentially palliative. GBMs are extremely resistant to conventional radiation and chemotherapies. We and others have demonstrated that a highly tumorigenic subpopulation of cancer cells called GBM stem cells (GSCs) promotes therapeutic resistance. We also found that GSCs stimulate tumor angiogenesis by expressing elevated levels of VEGF and contribute to tumor growth, which has been translated into a useful therapeutic strategy in the treatment of recurrent or progressive GBMs. Furthermore, stem cell-like cancer cells (cancer stem cells) have been shown to promote metastasis. Although GBMs rarely metastasize beyond the central nervous system, these highly infiltrative cancers often invade into normal brain tissues preventing surgical resection, and GSCs display an aggressive invasive phenotype. These studies suggest that targeting GSCs may effectively reduce tumor recurrence and significantly improve GBM treatment. Recent studies indicate that cancer stem cells share core signaling pathways with normal somatic or embryonic stem cells, but also display critical distinctions that provide important clues into useful therapeutic targets. In this review, we summarize the current understanding and advances in glioma stem cell research, and discuss potential targeting strategies for future development of anti-GSC therapies.     

基于化学遗传学筛选产萘醌类化合物内生放线菌

【目的】为探究含具有抗肿瘤活性的美登素的滑桃(Trewia nudiflora)种子中内生放线菌的多样性,以及从内生放线菌中寻找萘醌类化合物产生菌。【方法】利用放线菌富集筛选培养基对经消毒处理的滑桃种子进行内生菌分离,根据菌落形态及16S rRNA基因序列分析进行菌种的分类鉴定。通过对所分离到的内生放线菌拮抗模式病原细菌(金黄色葡萄球菌、铜绿假单胞菌)、作物病原真菌(小麦赤霉菌、水稻纹枯病致病菌等)活性检测,以及萘醌类化合物合成关键基因为探针定向筛选萘醌类化合物产生菌。【结果】从分离到的100余株滑桃种子内生菌中鉴定出66株以链霉菌为主的放线菌,发现Streptomyces sp.HTZ27菌株含有目标基因,经固体发酵、化合物分离纯化、鉴定后,发现该菌发酵产物中有呋喃萘醌I,得率接近5 mg/L。【意义】本研究采用的化学遗传学方法可有效提高筛选目标化合物产生菌的效率,所筛选到FNQ I产生菌为深入研究呋喃萘醌类化合物生物合成与调控、抗肿瘤分子机理以及产业化应用等创建了有利条件。     

筛选鉴定一株产生抑菌活性物质的海洋放线菌

目的：分离筛选能够产生抑菌活性物质的海洋放线茵,并进行生理生化和16SrDNA鉴定。方法：用分离培养基培养海洋放线菌,并筛选出能够产生抑菌活性物质的菌株,对所筛选菌株的形态特征、生理生化特性进行鉴定分析;采用通用引物27F、1492R扩增该菌株的16SrDNA,对测序结果进行分析;采用Neighbor—Joining（N—J）法构建系统发育进化树。结果：筛选到一株对金黄色葡萄球菌、大肠杆菌、白色念珠菌具有较强抗性的海洋放线菌F1,该菌株好氧,中度嗜盐,在高氏I号培养基上呈白色绒粉状,16SrDNA序列比对表明该菌株与田无链霉菌（Streptomyces tanashiensis）NR043369的相似度为99％。结论：筛选到的菌株F1是一株海洋来源的放线菌,与田无链霉菌NR043369的同源性较高,可能属海洋链霉菌属,对金黄色葡萄球菌等病原菌具有较强的抑菌活性。     

P53，Rb和c－myc基因在人脑原发性肿瘤中的转录表达

采用RNA斑点杂交分析,对21例人脑原发性胶质瘤和11例人脑膜瘤中p53,Rb和c-myc基因转录水平的表达进行研究.发现48.4%的肿瘤中p53基因表达减弱,21.9%的肿瘤中Rb基因表达减弱;71.9%的肿瘤中c-myc基因表达增强.在p53基因表达减弱的15例病例中有13例(80%)c-myc基因表达增强.结果表明,p53基因表达减弱和c-myc基因表达增强与人脑原发性肿瘤的发生有关.     

切鳍标记对唐鱼游泳能力的影响

本研究通过测定完全切除背鳍、臀鳍、尾鳍或双侧胸鳍后唐鱼（Tanichthys albonubes）临界游泳速度来评价切鳍标记对游泳能力的影响。研究结果表明,在速度增量（ΔU）为36 mm/s,持续时间（Δt）分别为5 min、10 min、15 min、20 min、25 min、30 min的条件下,唐鱼临界游泳速度会随着持续时间的延长而降低。鳍组织完整的唐鱼〔体长（24 ± 1）mm〕,在不同持续时间（Δt）条件下,其绝对临界游泳速度（Uacrit）为（251.98 ± 11.04）mm/s ~（333.78±12.44）mm/s;同等条件下,切除唐鱼的背鳍或臀鳍均不会对唐鱼的绝对临界游泳速度造成显著影响（P＞0.05）,但切除唐鱼的尾鳍或胸鳍后其临界游泳速度与对照组相比极显著降低（P＜0.01）,其中切除尾鳍后绝对临界游泳速度平均下降47.20%,切除胸鳍后平均下降22.98%,两者间存在极显著的差异（P＜0.01）(图2)。研究表明背鳍切除可作为野外唐鱼短期标记-重捕的手段之一。     

Water transport of native and exotic tree species in relation to xylem anatomical characteristics in low subtropical China

Aims Exotic fast-growing tree species have been commonly planted as pioneer species to facilitate ecological restoration in South China. Their growth and resource utilization behavior related to intrinsic physiology and structural properties have profound influences on forest ecosystem. However, the contrastive research focusing on water utilization features along with xylem anatomical properties between native and exotic species is scarce in South China. The objective of this study is to investigate the sapwood anatomical characteristics and water utilization conditions of native and exotic fast-growing species, and to elucidate the relationship between sap-flux density and conduit features.Methods We measured sap-flux density, conduit length, diameter and density of four native species (Schima superba, Michelia macclurei, Castanopsis hystrix and Castanopsis fissa) and four exotic species (Eucalyptus citriodora, Eucalyptus urophylla × grandis, Acacia auriculaeformis and Acacia mangium). Sap flux density was measured based on the Granier's thermal dissipation probe method. The whole-tree water transport was quantified by multiplying sap-flux density by sapwood area. The measurements of conduit characteristics were conducted by using segregation and slice method.Important findings Sapwood area increased with the growing diameter at breast height (DBH) as a power function. Native species had a larger water-conducting tissue area than exotic species at the same DBH value when trees grew to a size with a certain value of DBH. The conduit diameter of exotic species was significantly larger than that of native species. Conversely, native species, such as S. superba and M. macclurei, had longer conduit length and higher conduit density than other tree species. Based on a physiological interpretation of the measured conduit characteristics, native tree species developed a safe water transport system while exotic fast-growing tree species come into being an efficient system instead. Water transport increased with the growing DBH as a power function, and the exponent for native species (1.60) was higher than that for exotic species (1.22). Under the combined impact of sap-flux density and sapwood area, native species presented a larger water transport at a larger DBH value, indicating that growth advantage of exotic fast-growing species might weaken as DBH increased.     

城市带状绿地结构类型与温湿效应的关系

利用小尺度定量测定的方法,选择北京典型的城市带状绿地--西四环旁侧4种不同内部结构以及5种不同郁闭度带状绿地(绿地宽度42 m)作为研究对象,研究带状绿地结构类型与温湿效应的关系.结果表明:与对照相比,草坪的降温增湿效应不显著,灌-草、乔-草和乔-灌-草绿地的降温增湿效果显著.当郁闭度为10%～31%时,绿地具有一定的降温增湿效应,但效应不显著;当郁闭度超过44%时,绿地降温增湿效应显著;当郁闭度超过67%时,绿地降温增湿效应显著且趋于稳定.     

环化二磷酸腺苷核糖及其钙动员的功能

环化二磷酸腺苷核糖（cyclic ADP-ribose,cADPR）是烟酰胺腺嘌呤二核苷酸(NAD⁺)的代谢产物,是新近发现的一种细胞内第二信使．在许多哺乳类和无脊椎动物细胞中,cADPR能引起胞内钙库释放钙离子,其可能机制是：cADPR受体结合cADPR,通过Ryanodine受体或类Ryanodine受体介导的钙通道使cADPR敏感的钙库释放钙离子,此外,一条由一氧化氮（NO）、环化鸟苷酸（cGMP）和cADPR组成的细胞内信号转导途径可能存在于许多细胞中．     

Regulation of the Ca2+ sensitivity of the nonselective cation channel TRPM4

TRPM4, a Ca(2+)-activated cation channel of the transient receptor potential superfamily, undergoes a fast desensitization to Ca(2+). The mechanisms underlying the alterations in Ca(2+) sensitivity are unknown. Here we show that cytoplasmic ATP reversed Ca(2+) sensitivity after desensitization, whereas mutations to putative ATP binding sites resulted in faster and more complete desensitization. Phorbol ester-induced activation of protein kinase C (PKC) increased the Ca(2+) sensitivity of wild-type TRPM4 but not of two mutants mutated at putative PKC phosphorylation sites. Overexpression of a calmodulin mutant unable to bind Ca(2+) dramatically reduced TRPM4 activation. We identified five Ca(2+)-calmodulin binding sites in TRPM4 and showed that deletion of any of the three C-terminal sites strongly impaired current activation by reducing Ca(2+) sensitivity and shifting the voltage dependence of activation to very positive potentials. Thus, the Ca(2+) sensitivity of TRPM4 is regulated by ATP, PKC-dependent phosphorylation, and calmodulin binding at the C terminus.