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排序方式: 共有31条查询结果,搜索用时 29 毫秒
1.
We bred a microbial community capable of degrading rice straw with high efficiency. The microbial community degraded more than 60% of rice straw within 4 days at 50 °C. The high stability of the community's degradation ability was demonstrated by its tolerance of being subcultured several times in medium with/without cellulosic material, being heated to 95 °C, and freezing at –80 °C. The community degraded both nonsterilized and sterilized substrate; and its degradation ability was not affected by pH changes in the medium (initial pH 5–9). PCR-denaturing gradient gel electrophoresis (DGGE) analyses based on 16S rDNA fragments showed that the community structure remained constant after multiple subcultures extending over 2 years. DNA sequence analyses of DGGE bands indicated the coexistence of both aerobic and anaerobic bacteria in the community. Electronic Publication  相似文献
2.
Zou W  Li ZY  Li CL  Cui ZC 《生理科学进展》2000,31(2):120-124
蛋白激酶B(PKB)是原癌基因c-akt的表达产物,它参与由生长因子激活的经磷脂磷肌醇3-激酶(PI3K)介导的信号转导过程。与许多蛋白激酶相似,PKB分子具有一特殊的AH/PH结构域(AH/PHdomain),后者能介导信号分子间的相互作用。PKB是PI3K直接的靶蛋白。PI3K产生的脂类第二信使PI-3,4,P2和PI-3,4,5-P3等均能与PKB和磷酸肌醇依赖性蛋白激酶(PDK)的AH/P  相似文献
3.
Dietary-morphological relationships of fishes in Liangzi Lake, China   总被引:6,自引:0,他引:6  
S. Xie    Y. Cui  Z. Li 《Journal of fish biology》2001,58(6):1714-1729
Species in Liangzi Lake were clustered into four trophic groups: Hemiramphus kurumeus and Hemiculter bleekeri bleekeri fed predominantly on terrestrial insects; Carassius auratus auratus and Abbottina rivularis on non-animal food; Hypseleotris swinhonis, Ctenogobius giurinus, Pseudorasbora parva and Toxabramis swinhonis on cladocerans or copepods; Culterichthys erythropterus on decapod shrimps. Gut length, mouth width, mouth height, gill raker length and gill raker spacing, varied widely among species. With the exception of three species pairs ( H. swinhonis, C. giurinus; C. erythropterus, H. kurumeus; T. swinhonis, H. bleekeri bleekeri ), principal components analysis of morphological variables revealed over-dispersion of species. Canonical correspondence analysis of dietary and morphological data revealed five significant dietary-morphological correlations. The first three roots explained > 85% of the total variance. The first root reflected mainly the relationship of gut length to non-animal food, with an increase in gut length associated with an increase in non-animal food. The second root was influenced strongly by the relationship of the gill raker spacing to consumption of copepods, with an increase in gill raker spacing associated positively with copepods in the diet. The third root was influenced by the relationship of mouth gape to consumption of fish and decapod shrimps, with an increase in mouth gape associated with more fish and decapod shrimps in the diet. These significant dietary-morphological relationships supported the eco-morphological hypotheses that fish morphology influence food use, and morphological variation is important in determining ecological segregation of co-existing fish species.  相似文献
4.
Effects of rapid cooling on articular cartilage   总被引:2,自引:0,他引:2  
Guan J  Urban JP  Li ZH  Ferguson DJ  Gong CY  Cui ZF 《Cryobiology》2006,52(3):430-439
In order to improve the technique and protocols of cryopreservation of articular cartilage, a study was carried out to assess the effects of rapid cooling on the intact articular cartilage. Cartilage slices with a thickness ranging from 0.2 to 0.5 mm taken from bovine metacarpal-phalangeal joints were subjected to rapid cooling by immersing them in liquid nitrogen with and without treatment of the VS55 cryoprotective agent (CPA). The ultrastructure, chondrocyte viability, swelling property, and glycosaminoglycan (GAG) content were then examined before and after cryopreservation to give qualitative and quantitative evaluation on the functional state of both chondrocytes and extracellular matrix. The transmission electron microscopy study demonstrated that damage to chondrocytes without CPA was far more pronounced than those with VS55 protection while the structure of the extracellular matrix altered little in either group. The cell viability assay showed that although the exposure to VS55 led to about 36% chondrocytes losing membrane integrity, the VS55 could provide protection to chondrocytes during rapid cooling and thawing, with approximately 51% of the cells having survived rapid cooling compared to fewer than 5% in the absence of CPA. There were no significant differences in degrees of swelling or the GAG contents of cartilage slices after cryopreservation indicating rapid freezing caused little damage to the matrix. Future research activities include searching improved CPA formulation, optimising the treatment protocol and investigating the long-term effects of rapid cooling on articular cartilage.  相似文献
5.
Purification of lysozyme using ultrafiltration   总被引:2,自引:0,他引:2  
This article examines the separation of lysozyme from chicken egg white by ultrafiltration with 25 kDa and 50 kDa MWCO polysulfone membranes. The effects of pH, system hydrodynamics, feed concentration, and transmembrane pressure on permeate flux, lysozyme transmission, purification factor, and productivity have been discussed. With both types of membranes, higher permeate flux and lysozyme transmission were observed at higher pH. Higher lysozyme purity was generally obtained with the 25 kDa MWCO membrane. Purity of lysozyme decreased when the feed concentration was increased. With the 50 kDa MWCO membrane permeate flux, productivity and the purity of lysozyme were found to increase with increase in transmembrane pressure. The possibility of using a two-step ultrafiltration process for achieving high productivity along with high purity of lysozyme was also investigated.  相似文献
6.
In McA-RH7777 cells, the oleate-stimulated assembly and secretion of very low density lipoproteins (VLDL) was associated with enhanced deacylation of phospholipids, which was markedly decreased by inactivation of the cellular phospholipase A(2). Treatment of the cells with antagonists or antisense oligonucleotide of the Ca(2+)-independent phospholipase A(2) (iPLA(2)) significantly inhibited secretion of apoB100-VLDL and triglyceride. Similar inhibitory effect of the iPLA(2) antagonists was observed on apoB48-VLDL secretion, but secretion of high density lipoprotein particles (such as apoAI- and apoB48-high density lipoprotein) or proteins in general was unaffected. The iPLA(2) antagonist did not affect the synthesis of apoB100 or triglyceride, nor did it affect the activities of phospholipase D, phosphatidate phosphohydrolase, or microsomal triglyceride transfer protein. Inactivation of iPLA(2) resulted in impaired apoB100-VLDL assembly as shown by decreased apoB100-VLDL and triglyceride within the microsomal lumen, with concomitant increase in apoB100 association with the microsomal membranes. The inhibitory effect of iPLA(2) antagonists on apoB100-VLDL assembly/secretion could be abated by pretreatment of cells with oleate. Analysis of molecular species of microsomal phosphatidylcholine and phosphatidylethanolamine by electron spray tandem mass spectrometry revealed that the enrichment of oleoyl moieties was altered by the treatment of iPLA(2) antagonist. These results suggest that the oleate-induced VLDL assembly/secretion may depend upon the establishment of membrane glycerolipids enriched in oleoyl chain, a process mediated by the iPLA(2) activity.  相似文献
7.
钙离子/钙调素依赖性蛋白激酶Ⅱ及其功能   总被引:1,自引:0,他引:1  
所有引起细胞内钙离子浓度升高的激素或神经递质都可通过不同的钙离子/钙调素依赖性蛋白激酶达到调节细胞生理功能的作用。在神经元活动、细胞分泌、平滑肌缩等 细胞活动中起重要作用。  相似文献
8.
The production of IL-2, IL-6 by fetal splenic mononuclear cells (FSMC) and relationship between them and the ontogenetic development of natural killer cell function were studied in human fetal spleens. As a results, before 20 weeks of gestation, both IL-2 and NK cell activities were not measured, but IL-6 was done. It was found that IL-2, IL-6 and NK cell activities were increased with the gestational age, and shown that there were linear positive correlation between the activities of three ones above (r > 0.86). Before the birth, the induced IL-2 activity was the same as adult levels (p > 0.05), although both IL-6 production and NK activity in fetal spleens were significantly lower than that in adults (p < 0.01). Lastly, the production of IL-2, IL-6 in relation to the functional development of NK cells during the embryonic development was discussed.  相似文献
9.
作者自行设计一套小动物一氧化氮吸入系统,该系统主要包括有机玻璃舱,采气泵,流量计,NO/N2混和气体,纯氧,氮氧化物分析仪,O2,CO2监测仪。实验过程中,将6-7只大鼠置于舱内分别吸入20ppm,40ppm,80ppm和NO8h,每20min记录一次舱内NO,NO2,O2和CO2的浓度值。结果表明舱内的实测NO浓度与实验所设计的NO浓度相近,舱内氧浓度与空气中的氧浓度相似,NO和CO2最大浓度分  相似文献
10.
Hyperthermia, a modality of cancer therapy, has been known as a stress to induce apoptosis. However, the molecular mechanism of heat shock-induced apoptosis, especially on roles of intracellular oxidative stress, is not fully understood. First, when human lymphoma U937 cells were treated with heat shock (44C, 30 min), the fraction of apoptosis, revealed by phosphatidylserine externalization, increased gradually and peaked at 6 hr after the treatment. In contrast, intracellular superoxide formation increased early during the heat shock treatment and peaked at 30 min after the treatment. When the cells were treated with heat shock in the presence of -phenyl-N-tert-butylnitrone (PBN) and its derivatives, which are potent antioxidants, the DNA fragmentation was inhibited in an order according to the agents hydrophobicity. PBN showing the highest inhibitory effects suppressed not only intracellular superoxide formation but also various apoptosis indicators. cDNA microarray was employed to analyze gene expression associated with heat shock-induced apoptosis, and the time-course microarray analysis revealed 5 groups showing changes in their pattern of gene expression. Among these genes, c- jun mRNA expression showed more than 40 fold increase 2 hr after heat treatment. The expression level of c-jun mRNA verified by quantitative real-time PCR was about 20 fold increase, and c- jun expression was similarly suppressed by PBN and its derivatives. These results suggest that the change of c- jun expression is an excellent molecular marker for apoptosis mediated by intracellular oxidative stress induced by heat shock.  相似文献
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