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991.
Sang-Tian Yan Hao Zheng An Li Xue Zhang Xin-Hui Xing Li-Bing Chu Guoji Ding Xu-Lin Sun Benjamin Jurcik 《Bioresource technology》2009,100(21):5002-5009
Two lab-scale bioreactors (reactors 1 and 2) were employed to examine the changes in biological performance and the microbial community of an activated sludge process fed with ozonated sludge for sludge reduction. During the 122 d operation, the microbial activities and community in the two reactors were evaluated. The results indicated that, when compared with the conventional reactor (reactor 1), the reactor that was fed with the ozonated sludge (reactor 2) showed good removal of COD, TN and cell debris, without formation of any excess sludge. In addition, the protease activity and intracellular ATP concentration of reactor 2 were increased when compared to reactor 1, indicating that reactor 2 had a better ability to digest proteins and cell debris. DGGE analysis revealed that the bacterial communities in the two reactors were different, and that the dissimilarity of the bacterial population was nearly 40%. Reactor 2 also contained more protozoa and metazoa, which could graze on the ozone-treated sludge debris directly. 相似文献
992.
Chia-Liang Cheng Der-Shan Sun Wen-Chen Chu Yao-Hsuan Tseng Han-Chen Ho Jia-Bin Wang Pei-Hua Chung Jiann-Hwa Chen Pei-Jane Tsai Nien-Tsung Lin Mei-Shiuan Yu Hsin-Hou Chang 《Journal of biomedical science》2009,16(1):7
Bactericidal activity of traditional titanium dioxide (TiO2) photocatalyst is effective only upon irradiation by ultraviolet light, which restricts the potential applications of TiO2 for use in our living environments. Recently carbon-containing TiO2 was found to be photoactive at visible-light illumination that affords the potential to overcome this problem; although, the bactericidal activity of these photocatalysts is relatively lower than conventional disinfectants. Evidenced from scanning electron microscopy and confocal Raman spectral mapping analysis, we found the interaction with bacteria was significantly enhanced in these anatase/rutile mixed-phase carbon-containing TiO2. Bacteria-killing experiments indicate that a significantly higher proportion of all tested pathogens including Staphylococcus aureus, Shigella flexneri and Acinetobacter baumannii, were eliminated by the new nanoparticle with higher bacterial interaction property. These findings suggest the created materials with high bacterial interaction ability might be a useful strategy to improve the antimicrobial activity of visible-light-activated TiO2. 相似文献
993.
Linda J.S. Allen Curtis L. Wesley Robert D. Owen Douglas G. Goodin David Koch Colleen B. Jonsson Yong-Kyu Chu J.M. Shawn Hutchinson Robert L. Paige 《Journal of theoretical biology》2009,260(4):510-522
New habitat-based models for spread of hantavirus are developed which account for interspecies interaction. Existing habitat-based models do not consider interspecies pathogen transmission, a primary route for emergence of new infectious diseases and reservoirs in wildlife and man. The modeling of interspecies transmission has the potential to provide more accurate predictions of disease persistence and emergence dynamics. The new models are motivated by our recent work on hantavirus in rodent communities in Paraguay. Our Paraguayan data illustrate the spatial and temporal overlaps among rodent species, one of which is the reservoir species for Jabora virus and others which are spillover species. Disease transmission occurs when their habitats overlap. Two mathematical models, a system of ordinary differential equations (ODE) and a continuous-time Markov chain (CTMC) model, are developed for spread of hantavirus between a reservoir and a spillover species. Analysis of a special case of the ODE model provides an explicit expression for the basic reproduction number, , such that if , then the pathogen does not persist in either population but if , pathogen outbreaks or persistence may occur. Numerical simulations of the CTMC model display sporadic disease incidence, a new behavior of our habitat-based model, not present in other models, but which is a prominent feature of the seroprevalence data from Paraguay. Environmental changes that result in greater habitat overlap result in more encounters among various species that may lead to pathogen outbreaks and pathogen establishment in a new host. 相似文献
994.
995.
Lina Du Robert W. Hickey H��lya Bayir Simon C. Watkins Vladimir A. Tyurin Fengli Guo Patrick M. Kochanek Larry W. Jenkins Jin Ren Greg Gibson Charleen T. Chu Valerian E. Kagan Robert S. B. Clark 《The Journal of biological chemistry》2009,284(4):2383-2396
Sex-dependent differences in adaptation to famine have long been
appreciated, thought to hinge on female versus male preferences for
fat versus protein sources, respectively. However, whether these
differences can be reduced to neurons, independent of typical nutrient depots,
such as adipose tissue, skeletal muscle, and liver, was heretofore unknown. A
vital adaptation to starvation is autophagy, a mechanism for recycling amino
acids from organelles and proteins. Here we show that segregated neurons from
males in culture are more vulnerable to starvation than neurons from females.
Nutrient deprivation decreased mitochondrial respiration, increased
autophagosome formation, and produced cell death more profoundly in neurons
from males versus females. Starvation-induced neuronal death was
attenuated by 3-methyladenine, an inhibitor of autophagy; Atg7
knockdown using small interfering RNA; or l-carnitine, essential
for transport of fatty acids into mitochondria, all more effective in neurons
from males versus females. Relative tolerance to nutrient deprivation
in neurons from females was associated with a marked increase in triglyceride
and free fatty acid content and a cytosolic phospholipase A2-dependent
increase in formation of lipid droplets. Similar sex differences in
sensitivity to nutrient deprivation were seen in fibroblasts. However,
although inhibition of autophagy using Atg7 small interfering RNA
inhibited cell death during starvation in neurons, it increased cell death in
fibroblasts, implying that the role of autophagy during starvation is both
sex- and tissue-dependent. Thus, during starvation, neurons from males more
readily undergo autophagy and die, whereas neurons from females mobilize fatty
acids, accumulate triglycerides, form lipid droplets, and survive longer.Sex-dependent differences in adaptation to famine have long been
appreciated (1,
2), thought to hinge on a
female preference for fat sources, in contrast to a male preference for
protein sources (3). Fatty acid
metabolism is different between sexes normally
(4) and under conditions of
starvation (1,
2). During exercise, in
addition to increases in carbohydrate requirement, men increase their need for
amino acids, whereas women increase mobilization of fat
(5). Furthermore, sex-dependent
responses to nutritional stress associated with either self-induced weight
loss or illness-related cachexia also exist
(6,
7).An important adaptation to starvation is autophagy (autophagy-associated
proteins, abbreviated ATG). Classic, starvation-induced autophagy is initiated
by nutrient and amino acid deprivation, glucagon, and cAMP
(8,
9). ATG7, a ubiquitin E1-like
enzyme, is essential for autophagy, with phosphorylation of preautophagosomal
membranes, formation of ATG12-ATG5 complexes, and processing of ATG8/LC3
(microtubule-associated protein light chain-3) as other crucial steps in this
process (10).
Starvation-induced autophagy is regulated by class III phosphatidylinositol
3-kinase and the Bcl-2-interacting partner, Beclin-1
(11). The autophagosomes then
engulf cytoplasmic material and/or organelles, such as mitochondria, the
latter sometimes referred to as “mitophagy,” disassembling large
proteins and organelles to recycle amino acids and other nutrients, an
important response to starvation
(12).It is unknown whether starvation can induce autophagy in the brain;
however, there is evidence that critical starvation can result in brain
atrophy in humans. It has been reported that ∼30% of people during a
prolonged hunger strike (mean of 199 days) will show brain tissue loss
(13), and brain shrinkage in
patients with anorexia nervosa is well documented
(14,
15). Although 48 h of food
deprivation does not produce detectable autophagy in brains from mice
(16), the aforementioned
reports are consistent with long durations of starvation as a bona
fide stimulus for autophagy in brain. There are recent studies suggesting
that other stimuli can induce autophagy in the brain, such as trauma
(17) and ischemia
(18), and that autophagy may
contribute to neuronal death. There is also evidence for autophagy in the
human brain after trauma and critical illness
(19), which probably includes
both elements of malnutrition and systemic stress. A potential role for brain
atrophy as a contributor to neurological morbidity in the critically ill and
injured is an emerging topic
(20). 相似文献
996.
自然条件下滤减UV-B辐射对烤烟光合色素含量的影响 总被引:1,自引:0,他引:1
在自然环境中,以烟草栽培品种K326为材料,通过覆盖不同透明薄膜滤减UV—B辐射,研究100%(CK)、75%(T1)、50%(T2)、35%(T3)UV—B辐射透过率处理下,不同强度UV—B辐射对烟草光合色素含量的影响。结果表明:烤烟三类光合色素对UV—B辐射有不同响应。类胡萝卜素对UV—B辐射响应较敏感。成熟初期,类胡萝卜素含量与UV—B辐射强度变化具有较好的正相关性,而chl a和chl b含量基本与UV—B辐射强度呈反向变化关系。成熟后期,由于UV—B辐射累积效应,光合色素含量变化没有明显规律。现蕾期至成熟采烤烟初期,chl a:chl b与UV—B辐射的反向变化关系较明显,后期则无明显规律,其含量的下降与UV—B辐射的累积效应有关。 相似文献
997.
UV-B滤减处理下烟草光合作用参数对光照度的响应 总被引:3,自引:0,他引:3
以烟草栽培品种K326为材料,通过覆盖不同的透明薄膜滤减UV-B辐射,研究了100%(CK)、75%(T1)、50% (T2)、35%(T3)UV-B辐射透过率处理下,烟草成熟初期光合参数与50和150 cm高度光照度的关系。结果表明:对于T1、T3,烟叶净光合速率的变化主要是气孔因素,而T2主要是非气孔因素;通过对4类处理的平均水分利用效率的比较,发现可能存在一个UV-B辐射对水分利用效率影响的阈值范围;150 cm高度光照度除了对蒸腾速率和T2处理的气孔导度起促进作用外,对其他光合参数都有一定的抑制作用;而不同处理的烟叶光合参数对50和150 cm高度上的光照度的响应都较为一致,在敏感程度上则存在差异。 相似文献
998.
目的:观察鞘内给予N-甲基-D-天门冬氨酸(NMDA)受体拮抗剂MK-801对足底注射甲醛诱导的自发痛反应和海马一氧化氮合酶(NOS)表达及一氧化氮(N0)含量的影响,探讨炎性痛诱导海马NO产生增多的机制。方法:通过观察舔足反射时间反映大鼠自发痛程度;采用NADPH—d组织化学法测定大鼠海马NOS表达;硝酸还原酶法测定海马组织NO含量。结果:足底注射甲醛后动物即出现舔、咬、摇动注射侧脚掌等自发痛相关表现,预先鞘内注射MK-801可使大鼠第二时相自发病程度显著降低,但对第一时相痛反应程度无明显影响。注射甲醛后12h时,海马CA1、CA2~3区及DG区NOS阳性细胞数目、阳性细胞染色深度均显著增加,海马组织NO含量显著增加;预先鞘内注射MK-801,可使甲醛炎性痛大鼠海马各区NOS阳性细胞数目明显减少,阳性细胞染色深度明显变浅,海马NO含量明显降低。结论:鞘内注射MK-801可逆转甲醛炎性痛诱导的海马NOS表达及NO产生的增加,表明甲醛炎性痛诱导的海马NO产生增加主要是由于伤害性信息传入所引起。 相似文献
999.
Guang Liang Lili Shao Yi Wang Chengguang Zhao Yanhui Chu Jian Xiao Yu Zhao Xiaokun Li Shulin Yang 《Bioorganic & medicinal chemistry》2009,17(6):2623-2631
Curcumin has a surprisingly wide range of chemo-preventive and chemo-therapeutic activities and is under investigation for the treatment of various human cancers. However, the clinical application of curcumin has been significantly limited by its instability and poor metabolic property. Although a number of synthetic modifications of curcumin have been studied intensively in order to develop a molecule with enhanced bioactivities, few synthetic studies were done for the improvement of pharmacokinetic profiles. In the present study, a series of mono-carbonyl analogues of curcumin were designed and synthesized by deleting the reactive β-diketone moiety, which was considered to be responsible for the pharmacokinetic limitation of curcumin. The results of the in vitro stability studies and in vivo pharmacokinetic studies indicated that the stability of these mono-carbonyl analogues was greatly enhanced in vitro and their pharmacokinetic profiles were also significantly improved in vivo. Furthermore, the cytotoxic activities of mono-carbonyl analogues were evaluated in seven different tumor cell lines by MTT assay and the structure–activity relation (SAR) was discussed and concluded. The results suggest that the five-carbon linker-containing analogues of curcumin may be favorable for the curcumin-based drug development both pharmacokinetically and pharmacologically. 相似文献
1000.
蚂蚁是分布广泛、种类和数量丰富的社会性昆虫.蚂蚁的传统分类学研究存在一定局限性,而分子生物学为蚂蚁的系统学研究提供了新途径.概述了蚂蚁分子系统学在研究内容和技术方法上的研究进展,并对今后的研究做了展望. 相似文献