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951.
一种简单有效且适于土壤微生物多样性分析的DNA提取方法 总被引:1,自引:0,他引:1
参照Zhou[11]的方法进行了改进,获得了一种简单、有效的DNA提取方法.此方法操作简单、从大量样品改为小量样品的提取,利用高浓度的PEG沉淀,不作回收纯化,所提DNA片段较大,在23 kb以上,每克土的DNA提取量从3.74~15.28 μg,OD260/OD230比值在0.89~1.21范围内,用真菌和细菌核糖体特异性引物进行PCR扩增,均获得较好的结果,DGGE图谱显示丰富性较高,可用于细菌多样性和真菌多样性的分析.此方法能够从4种不同性质土壤中提取出DNA,但提取盐渍土壤和碱性土壤的效果更好一些,为土壤微生物群落结构的多样性分析奠定良好的基础. 相似文献
952.
Endomorphin 1 (EM1), an endogenous µ‐opioid receptor agonist, acts as a free radical scavenger in vitro and an antioxidant in vivo. The modification of EM1 by ROS and the properties of the OM attracted our attention. In vitro assays were performed via RP‐HPLC, spectrophotometric measurements, EPR and amino acid analysis, Schmorl's reaction to define the formation of melanin‐like compounds transformed from EM1, collectively named EM1–melanin and by solubility assay, radioligand‐binding assay, NADH oxidation, superoxide anion scavenging assay to study some physical and chemical properties of EM1–melanin. Possible pathways of the formation of EM1–melanin were proposed. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
953.
Interleukin-6 and neural stem cells: more than gliogenesis 总被引:1,自引:0,他引:1
954.
XinXing Wang XiaoHua Liu RuiRui Kong Rui Zhan XiaoMing Wang Xue Leng JingBo Gong Meng Duan LiQun Wang Lei Wu LingJia Qian 《Cell stress & chaperones》2009,14(6):639-648
NGFI-B/Nur77/TR3, originally identified as an immediate-early gene rapidly induced by serum and growth factors, is a member of the steroid hormone nuclear receptor superfamily with no identified endogenous ligand. NGFI-B induces apoptosis in a number of cell lineages exposed to proapoptotic stimuli by directly targeting the mitochondria, inducing cytochrome c release. The present study was designed to determine the role of NGFI-B in cardiomyocytes of restraint-stressed rats. The NGFI-B content was increased in mitochondria and reduced in plasma as apoptosis increased. Analysis showed that NGFI-B induces cardiomyocyte apoptosis in restraint-stressed rats by mediating mitochondrial energy metabolism disorder. Several novel mitochondrial proteins, which correlate with NGFI-B, were reported in cardiomyocyte apoptosis of restraint-stressed rats. Five proteins associated with NGFI-B participate directly in mitochondrial energy metabolism. Studies of mitochondrial respiratory efficiency and ATP synthase activity strongly support the findings. These results provide significant information for comprehensively understanding the cellular mechanism of cardiovascular diseases. 相似文献
955.
W. Si † X. Ni ‡ J. Gong H. Yu R. Tsao Y. Han J.R. Chambers 《Journal of applied microbiology》2009,106(1):213-220
Aims: To assess the potential of essential oils and structurally related synthetic food additives in inhibiting the growth of Clostridium perfringens for the control of necrotic enteritis in chickens.
Methods and Results: The antimicrobial activity of essential oils/compounds was measured by determining the inhibition of bacterial growth. Thirty-three of 66 oils/compounds exhibited ≥80% inhibition. Seven with the highest potency were further studied. The oils/compounds had MIC95 values between 167 and 425 μ g ml−1 . Most of them were tolerant to low pH (2·0) and exhibited minor or no inhibition of Lactobacillus isolates from the chicken intestine. When mixed with chicken ileal digesta, the oils/compounds retained their efficacy against C . perfringens , but had little effect on the total number of lactobacilli and anaerobic bacteria in the digesta.
Conclusions: Some essential oils/compounds demonstrated good potential in controlling C . perfringens .
Significance and Impact of the Study: This study has identified candidates of essential oils/compounds for in vivo studies for the control of necrotic enteritis in chickens. 相似文献
Methods and Results: The antimicrobial activity of essential oils/compounds was measured by determining the inhibition of bacterial growth. Thirty-three of 66 oils/compounds exhibited ≥80% inhibition. Seven with the highest potency were further studied. The oils/compounds had MIC
Conclusions: Some essential oils/compounds demonstrated good potential in controlling C . perfringens .
Significance and Impact of the Study: This study has identified candidates of essential oils/compounds for in vivo studies for the control of necrotic enteritis in chickens. 相似文献
956.
Spatial distribution as a measure of conservation needs: an example with Asiatic black bears in south-western China 总被引:1,自引:0,他引:1
Fang Liu William McShea David Garshelis Xiaojian Zhu Dajun Wang Ji'en Gong Youping Chen 《Diversity & distributions》2009,15(4):649-659
Aim To create a fine‐scale map of the distribution of Asiatic black bears, identify landscape variables affecting the spatial range of this species and assess population trends using presence–absence data and opinions of local villagers. Location Sichuan Province, south‐western China. Methods We divided the province into 15 × 15 km cells, stratified them by forest cover, elevation and road density and randomly selected 494 cells (21% of province) for surveys. In each cell, we interviewed villagers and ground‐verified their reports of bear presence. We ground‐truthed reports of bear absence by conducting transects for bear sign in the best available habitat. We used logistic regression to identify key variables affecting presence of bears and predict their occurrence in unsampled cells. Results We detected bears in 360 cells (73%). Models correctly predicted bear occurrence in 90.3% of cells where we detected bears and 84.5% of sampled cells where bears were absent. Models predicted 42.7% of Sichuan to be occupied by bears. Bear occurrence was strongly related to forest cover throughout the province. Roads had a negative effect in western region of province. Agricultural lands had a negative effect only when they were distant from forests. Villagers were accurate in their knowledge of bear presence or absence. Interviewed villagers (n = 1816) thought that bears were increasing in 32%, stable in 10%, and decreasing in 58% of cells with bears. Where bear populations were perceived to be declining, villagers identified poaching as the most common cause. Main conclusions Our fine‐scale distribution map can be used for future monitoring and the key landscape factors related to occupancy by bears can be used in management plans for this species. Interviewing local villagers is an efficient and reliable means of assessing distribution, and changes therein, for animals such as bears that often interact with people and leave obvious signs. 相似文献
957.
958.
Maokai Gong 《Biochemical and biophysical research communications》2009,379(4):1001-1004
Paraoxonase 1 (PON1) protects the oxidative modification of low-density lipoprotein (LDL) and is a major anti-atherosclerotic protein component of high-density lipoprotein (HDL). Quercetin, a ubiquitous plant flavonoid, has been shown to have a number of bioactivities and may offer a variety of potential therapeutic uses. We explored the roles of quercetin in the regulation of PON1 expression, serum and liver activity and protective capacity of HDL against LDL oxidation in rats. Compared to the pair-fed control group, feeding quercetin (10 mg/L) in the liquid diet for 4 weeks increased (a) hepatic expression of PON1 by 35% (p < 0.01), (b) serum and liver PON1 activities by 29% (p < 0.05) and 57% (p < 0.01), respectively, and (c) serum homocysteine thiolactonase (HCTL) activity by 23% (p < 0.05). Correspondingly, the lag time of low-density lipoprotein (LDL) oxidation was increased by >3-fold (p < 0.001) with plasma HDL from quercetin-fed group compared to the HDL from control group. Our data suggest that quercetin has antiatherogenic effect by up regulating PON1 gene expression and its protective capacity against LDL oxidation. 相似文献
959.
960.
Min Xu Lin Bai Yong Gong Wei Xie Haiying Hang Tao Jiang 《The Journal of biological chemistry》2009,284(31):20457-20461
Cellular DNA lesions are efficiently countered by DNA repair in conjunction with delays in cell cycle progression. Previous studies have demonstrated that Rad9, Hus1, and Rad1 can form a heterotrimeric complex (the 9-1-1 complex) that plays dual roles in cell cycle checkpoint activation and DNA repair in eukaryotic cells. Although the 9-1-1 complex has been proposed to form a toroidal structure similar to proliferating cell nuclear antigen (PCNA), which plays essential roles in DNA replication and repair, the structural basis by which it performs different functions has not been elucidated. Here we report the crystal structure of the human 9-1-1 complex at 3.2 Å resolution. The crystal structure, together with biochemical assays, reveals that the interdomain connecting loops (IDC loop) of hRad9, hHus1, and hRad1 are largely divergent, and further cocrystallization study indicates that a PCNA-interacting box (PIP box)-containing peptide derived from hFen1 binds tightly to the interdomain connecting loop of hRad1, providing the molecular basis for the damage repair-specific activity of the 9-1-1 complex in contrast to PCNA. Furthermore, structural comparison with PCNA reveals other unique structural features of the 9-1-1 complex that are proposed to contribute to DNA damage recognition.Cellular DNA damage triggers the activation of the cell cycle checkpoint, leading to a delay or arrest in cell cycle progression to prevent replication and inducing DNA damage repair (1, 2). In response to DNA damage, the 9-1-13 complex can be loaded onto DNA lesion sites by Rad17-RFC2–5 (which consists of one large subunit, Rad17, and four small subunits, RFC2–5), where it triggers the activation of the cell cycle checkpoint (3, 4). Moreover, the 9-1-1 complex can also directly participate in DNA repair via physical association with many factors involved in base excision repair (BER), translesion synthesis, homologous recombination, and mismatch repair pathways (5–9).Although both the 9-1-1 and the PCNA complexes perform critical functions in eukaryotic cells with predicted similar structures (10), their specific roles are distinct. First, the 9-1-1 complex is a DNA damage sensor in the cell cycle checkpoint but does not function as a scaffold for the major DNA replication factors; however, PCNA plays exactly the opposite role (1, 11). Second, although both the complexes function in DNA repair, their specific activities are different. Previous observations indicated that some BER enzymes, such as MYH (MutY glycosylate homolog) (12), TDG (thymine DNA glycosylate) (7), and NEIL (Nei-like glycosylate) (8), interact with the 9-1-1 complex via motifs that are located outside the conserved PCNA-interacting box (the PIP box), implying that the 9-1-1 complex functions as a damage repair-specific clamp, in contrast to PCNA. However, the structural basis for this hypothesis remains unclear. Another important unresolved issue concerns the damage-sensing mechanism of the 9-1-1 complex. During the DNA replication process, the PCNA·RFC clamp·clamp loader specifically recognizes the primer-template junction (13). However, the molecular basis by which the 9-1-1·Rad17-RFC2–5 clamp·clamp loader specifically recognizes the damaged DNA is little known. To address these questions, we performed structural and biochemical studies on the 9-1-1 complex. 相似文献