首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   21篇
  完全免费   3篇
  2015年   1篇
  2014年   3篇
  2013年   4篇
  2012年   2篇
  2011年   8篇
  2010年   2篇
  2009年   3篇
  2008年   1篇
排序方式: 共有24条查询结果,搜索用时 62 毫秒
1.
During the summer of 2008 and 2009, massive algal blooms repeatedly broke out in the Yellow Sea of China. These were undoubtedly caused by the accumulations of one or more species in the macroalgal genus Ulva. In previous reports, morphological observation indicated that the species involved in this phenomenon is Ulva prolifera but molecular analyses indicated that the species belongs to an Ulva linza–procera–prolifera (LPP) clade. Correct identification of the bloom species is required to understand and manage the blooms, but the taxonomic status of the bloom species remains unclear. In the current study, the taxonomic status of 22 selected specimens from the Yellow Sea was assessed by using both morphological and molecular (ITS and rbcL sequences) data. In addition, 5S rDNA analyses were performed for those samples clustering in the LPP clade, and phylogenetic tree and ribotype analyses were constructed for determining the possible origin of the bloom. Three free-floating and two attached Ulva species were distinguished and described: Ulva compressa Linnaeus and Ulva pertusa Kjellman were found in free-floating samples; U. linza Linnaeus was found on rocks; and U. prolifera O.F. Müller was found in both habitats. Diversity in free-floating Ulva of the Yellow Sea appears to be greater than previously thought. The dominant free-floating Ulva species, U. prolifera, was not closely related to local populations attached to rocks but was closely related to populations from Japan.  相似文献
2.
3.
Periodontal ligament-associated protein-1 (PLAP-1) is a newly discovered member of the extracellular matrix family of proteins known as proteoglycans and is a negative regulator that plays a crucial role in the homeostasis of periodontal tissues. It can protect the periodontal ligament from excessive osteogenesis. However, the molecular mechanisms of PLAP-1 during osteogenic differentiation and osteogenesis remain unclear. In this study, we constructed a PLAP-1 recombinant retroviral plasmid vector named pBABE-hygro-PLAP-1. We transfected this plasmid into rat bone marrow stromal cells (rBMSCs) to obtain a stable cell line with overexpression of PLAP-1 to verify whether PLAP-1 also acts as an inhibitory factor in rBMSCs during bone mineralization. A rBMSC line stably overexpressing PLAP-1 was established successfully as determined by the mRNA levels of PLAP-1, which were measured by real time-qPCR (RT-qPCR), and protein expression, which was measured by immunocytochemistry and western blot analysis. At the same time, a Cell Counting Kit-8 assay did not reveal any statistically significant changes in the transfected cells (P > 0.05). Then, mineral-inducing cultures were performed, and mineralized nodules were observed at weeks 2, 3 and 4 under a microscope. Alizarin Red (Sigma) staining was performed at 4 week to illustrate calcium accumulation. The mineralized nodules in the PLAP-1-transfected rBMSC group were fewer than those in the control groups. The time span of the formation of the mineralized nodules was prolonged. Meanwhile, osteogenic genes were also detected in the mineral-inducing cells by RT-qPCR. An RT-qPCR analysis demonstrated that the levels of the osteoblast markers of rBMSCs that were transfected with pBABE-hygro-PLAP-1, including Runx2, Osterix, alkaline phosphatase, bone sialoprotein and osteocalcin, were lower than those in the non-transfected rBMSCs and rBMSCs that were transfected with empty vector (P < 0.01). These results suggest that PLAP-1 has an inhibitory function in rBMSCs when they differentiate into osteoblast-like cells.  相似文献
4.
5.
Shadoo (Sho) is an N-glycosylated glycophosphatidylinositol-anchored protein that is expressed in the brain and exhibits neuroprotective properties. Recently, research has shown that a reduction of Sho levels may reflect the presence of PrPSc in the brain. However, the possible mechanism by which prion infection triggers down-regulation of Sho remains unclear. In the present study, Western blot and immunohistochemical assays revealed that Sho, especially glycosylated Sho, declined markedly in the brains of five scrapie agent-infected hamsters and mice at the terminal stages. Analyses of the down-regulation of Sho levels with the emergence of PrPSc C2 proteolytic fragments did not identify close association in all tested scrapie-infected models. To further investigate the mechanism of depletion of Sho in prion disease, a Sho-expressing plasmid with HA tag was introduced into a scrapie-infected cell line, SMB-S15, and its normal cell line, SMB-PS. Western blot assay revealed dramatically decreased Sho in SMB-S15 cells, especially its glycosylated form. Proteasome inhibitor MG132 reversed the decrease of nonglycosylated Sho, but had little effect on glycosylated Sho. N-acetylglucosamine transferase inhibitor tunicamycin efficiently reduced the glycosylations of Sho and PrPC in SMB-PS cells, while two other endoplasmic reticulum stress inducers showed clear inhibition of diglycosylated PrPC, but did not change the expression level and profile of Sho. Furthermore, immunoprecipitation of HA-Sho illustrated ubiquitination of Sho in SMB-S15 cells, but not in SMB-PS cells. We propose that the depletions of Sho in scrapie-infected cell lines due to inhibition of glycosylation mediate protein destabilization and subsequently proteasome degradation after modification by ubiquitination.  相似文献
6.
Inhibition of c-MYC has been considered as a potential therapy for lymphoma treatment. We explored a lentiviral vector-mediated small interfering RNA (siRNA) expression vector to stably reduce c-MYC expression in B cell line Jijoye cells and investigated the effects of c-MYC downregulation on cell growth, cell cycle, and apoptosis in vitro. The expression of c-MYC mRNA and protein levels were inhibited significantly by c-MYC siRNA. The c-MYC downregulation resulted in the inhibition of cell proliferation and cell cycle arrest at G2/M phase, which was associated with decreased expression of cyclin B and cyclin-dependent kinase 1 (CDK1) and increased expression of CDK inhibitor p21 proteins. In addition, downregulation of c-MYC induced cell apoptosis characterized by DNA fragmentation and caspase-3 activation. Taken together, these results suggest that lentiviral vector-mediated siRNA for c-MYC may be a promising approach for targeting c-MYC in the treatment of Burkitt lymphoma.  相似文献
7.

Background and aims

Roots of the lowest branch orders have the highest mortality rate, and may contribute predominately to plant carbon (C) and nutrient transfer into the soil. Yet patterns and controlling factors of the decomposition of these roots are poorly understood.

Methods

We conducted a two-year field litterbag study on different root orders and leaf litter in four temperate and four subtropical tree species.

Results

Five species showed slower decay rates in lower- (order 1–2) than higher-order (order 3–5) roots, and all species showed slower decay rates in lower-order roots than leaf litter. These patterns were strongly related to higher acid-insoluble fraction in lower- than higher-order roots, and in roots than in leaf litter, but were unrelated to initial N concentration. Litter N was predominantly in recalcitrant forms and limited amount of N was released during the study period;only 12 % of root N and 26 % of leaf litter N was released in 2 years.

Conclusions

We conclude that the slow decomposition of lower-order roots may be a common phenomenon and is mainly driven by their high acid-insoluble fraction. Moreover, litter N, especially root N, is retained during decomposition and may not be available for immediate plant uptake.  相似文献
8.
从酒曲中筛选出一株高产蛋白酶的菌株,命名为OPY6,初步鉴定为假单胞菌Pseudomonassp.,经Plackett.BurmanDesign设计和Box.Behnken响应面设计对其产酶培养基做了优化,最优产酶条件为:葡萄糖2.83%,淀粉0.87%,酵母膏0.55%,氯化钙0.001%,氯化钠0.5%,黄豆粉1%,初始pH=7.0,在最佳培养基添加量下蛋白酶活提高到134.718U/mL;又对该酶在水产蛋白降解过程中的酶解效果进行了评价。  相似文献
9.
目的:探讨胰十二指肠切除手术后肠道细菌移位(BT)与术后全身炎症反应综合征(SIRS)关系。方法:40例择期行胰十二指肠切除手术患者,于术前和术后1、3、5天采集外周血,进行血浆D-乳酸,全血细菌DNA检测.全血DNA提取后进行PCR扩增,采用靶基因为大肠杆菌特异性β半乳糖苷酶基因和16SrRNA基因。观察患者术后10天以监测SIRS情况。结果:术前PCR检测全血细菌DNA均为阴性,术后共有13例阳性。术后出现全身炎症反应综合征(SIRS)的患者PCR阳性率为85.7%(12/14),无SIRS组为3.8%(1/26()P〈0.01)。PCR阳性组SIRS发生率为93.2%(12/13),阴性组为7.4%(2/27)(P〈0.01).PCR阳性的患者外周血血浆D-乳酸浓度较PCR阴性者明显升高(P〈0.01),有SIRS的患者外周血血浆D-乳酸浓度较无SIRS患者明显升高(P〈0.01)。结论:胰十二指肠切除术后肠黏膜屏障损伤与BT关系密切,术后SIRS和与BT密切相关。PCR技术对术后SIRS有较好的早期预警价值。  相似文献
10.
李远  董晓辉  邹作君 《生物磁学》2011,(13):2528-2531
目的:研究复方α-酮酸对维持性血液透析(MHD)患者营养及脂质代谢的影响。方法:将40例MHD患者随机分为两组:(1)实验组(n=20),予常规蛋白饮食,并服用复方α-酮酸12片/d;(2)对照组(n=20),子常规蛋白饮食,不服用复方α-酮酸。分别于治疗前、治疗后3个月后测定各项血生化指标及人体测量学指标。结果:经3个月治疗后,实验组血白蛋白、前白蛋白较前明显升高(P〈0.01),总胆固醇和甘油三酯明显下降(P〈0.01),血红蛋白无明显变化(P〉0.05);对照组血红蛋白、血白蛋白、前白蛋白及血脂无明显变化;实验组及对照组治疗前后体重指数、肱三头肌皮褶厚度、上臂肌围无明显变化(P〉0.05)。结论:复方α-酮酸可有效改善维持性血液透析患者营养状况以及脂质代谢,但长期使用该疗法的疗效和安全性有待于进一步的研究。  相似文献
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号