Advancements in endometrial epithelial stem cell research

Science China Life Sciences -     

高效液相色谱法测定大黄素在Caco-2细胞中的摄取

目的:采用反相高效液相色谱法,观察大黄素在Caco-2细胞中的摄取特点。方法:将大黄素与Caco-2细胞共同孵育,收集细胞样品,液氮反复冻融。取细胞裂解液,加入甲醇提取,提取液采用HPLC进行分析。色谱分析柱为C18柱(250mm×4．6mm,5μm,Diamonsil),流动相组成为85%乙腈及15%水(含0．1%乙酸),流速1ml·min-1,进样量20μl,柱温25℃,3D模式采集数据。结果:检测Caco-2细胞中大黄素的工作曲线的回归方程为Y=0．278x 0．148(Y=0．9996,n=5),线性范围为0．037～4．8μmol·L-1,最低检测浓度为0．018μmol·L-1。当细胞中大黄素的浓度为0．05、2和8．5μg·ml-1时,回收率分别为(101．3±7．3)%、(96．7±3．0)%和(98．7±2．1)%(n=5);相应的日内标准偏差分别为0．25%、2．9%和1．4%;相应的日间标准偏差分别为2．3%、5．6%和6．3%。大黄素在Caco-2细胞中的摄取达峰时间为10分钟,峰浓度为108．56±11．57 nmol/L·mg·protein,10分钟后Caco-2细胞中大黄素的含量迅速下降。浓度处于2-50μM之间时,Caco-2细胞对大黄素的摄取量呈线性增加,浓度达50μM后,随着剂量的增加大黄素的摄取量变化不明显。结论:大黄素可被Caco-2细胞迅速摄取,随着剂量的增加,大黄素在Caco-2细胞中的摄取存在饱和现象。     

4株鸽新城疫病毒的基因组序列与致病性分析

本研究对从北京、天津以及山东地区发病鸽群中分离到的4株鸽新城疫病毒（Newcastle disease virus,NDV）进行基因组测序和遗传进化分析,并进一步比较这些毒株对鸽子的致病性。研究通过特异性引物扩增4株鸽NDV的全长基因组序列后与GenBank上已登陆的所有鸽NDV毒株的序列进行遗传进化分析;通过病毒生物学特性的测定比较分离株的毒力;通过病毒感染1月龄肉鸽,检测分离株对鸽子的致病性。结果显示4株鸽NDV毒株均属于ClassⅡ类基因Ⅵb亚型病毒,其中Pigeon/China/BJ2018株、Pigeon/China/TJ2017株和Pigeon/China/BJ2013株属于VIb/4bii f亚型,Pigeon/China/SD2012株属于VIb/4bii d亚型。4株病毒与目前国内鸽NDV流行株属于同一进化分支,与鸡源经典疫苗株La Sota属于不同进化分支。对这四个毒株进行生物学特性测定,均为中等毒力毒株。4株病毒中,Pigeon/China/BJ2018株对1月龄肉鸽的致病性最强,通过肌肉注射途径攻毒后3d肉鸽开始表现临床症状,攻毒后第5d开始出现死亡,累计死亡率...     

韭菜化感物质草莓酸对香蕉枯萎病菌的影响

香蕉枯萎病主要由尖孢镰刀菌 4 号生理小种(Fusarium oxysporum f. sp. cubense,Foc4)引起的一种土传病害,严重威胁香蕉产业的可持续发展。为寻求一种经济有效且环保的防治措施,以韭菜化感物质的衍生物草莓酸(strawberry acid,SA)为材料,通过平板和盆栽实验,研究了SA对Foc4的菌丝生长、香蕉枯萎病病情指数、土壤微生物数量、土壤酶活性的影响。结果表明:(1)随着SA浓度的增加,Foc4的菌落生长直径显著减小,第5天时菌落直径在SA浓度为300、450 μL·L^-1时比150 μL·L^-1分别减小了49.15%、70.89%; 液体培养条件下SA浓度为600 μL·L^-1时Foc4的分生孢子数量显著低于对照处理(相差 470 多倍); pH为5时SA对Foc4的抑制效果显著比pH为7和9时好。(2)随实验处理时间的延长,添加 SA后香蕉幼苗的病情指数显著低于对照。(3)土壤细菌、真菌数量和微生物总量在SA为600 μL·L^-1时均为最高; Foc4数量随SA浓度升高而降低,在1 200 μL·L^-1时显著降低。(4)各土壤酶在浓度(300～600 μL·L^-1)SA处理时活性较高; 1 200 μL·L^-1时显著降低,过氧化氢酶和多酚氧化酶较对照分别降低了41.88%、54.82%。(5)相关性分析得出,土壤微生物总量与细菌、真菌数量极显著正相关; 土壤真菌与放线菌显著负相关; 土壤细菌、真菌和放线菌数量均与蔗糖酶、多酚氧化酶显著正相关; 蔗糖酶与脲酶、过氧化氢酶与多酚氧化酶均显著正相关。综上认为,添加SA浓度为600 μL·L^-1能较好地抑制Foc4的菌丝生长且能提高其抑制率,病情指数明显降低,有利于改善香蕉的生长环境。该研究结果为有效利用SA防治香蕉枯萎病提供了科学依据。     

Sucrose transporters of resistant grapevine are involved in stress resistance

Plant Molecular Biology - The whole promoter regions of SUTs in Vitis were firstly isolated. SUTs are involved in the adaptation to biotic and abiotic stresses. The vulnerability of Vitis vinifera...     

Cyclin-dependent kinase-5 is involved in neuregulin-dependent activation of phosphatidylinositol 3-kinase and Akt activity mediating neuronal survival

The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway plays an important role in mediating survival signals in wide variety of neurons and cells. Recent studies show that Akt also regulates metabolic pathways to regulate cell survival. In this study, we reported that cyclin-dependent kinase-5 (Cdk5) regulates Akt activity and cell survival through the neuregulin-mediated PI 3-kinase signaling pathway. We found that brain extracts of Cdk5-/-mice display a lower PI 3-kinase activity and phosphorylation of Akt compared with that in wild type mice. Moreover, we demonstrated that Cdk5 phosphorylated Ser-1176 in the neuregulin receptor ErbB2 and phosphorylated Thr-871 and Ser-1120 in the ErbB3 receptor. We identified the Ser-1120 sequence RSRSPR in ErbB3 as a novel phosphorylation consensus sequence of Cdk5. Finally, we found that Cdk5 activity is involved in neuregulin-induced Akt activity and neuregulin-mediated neuronal survival. These findings suggest that Cdk5 may exert a key role in promoting neuronal survival by regulating Akt activity through the neuregulin/PI 3-kinase signaling pathway.     

The Commelina yellow mottle virus promoter drives companion-cell-specific gene expression in multiple organs of transgenic tobacco

Summary.  Previous work has demonstrated that some endogenous plant gene promoters are active in selective companion cells of the phloem, depending on organ types and developmental stages. Here we report that the Commelina yellow mottle virus (CoYMV) promoter is active in the companion cells of leaves, stems and roots of transgenic Nicotiana tabacum cv. Xanthi NN, using β-glucuronidase (GUS) as a reporter. Thus, the CoYMV promoter has a broad organ specificity. This promoter can be useful in molecular studies on the functions of companion cells in many aspects of phloem biology, such as regulation of long-distance transport, macromolecular traffic, plant development and interaction with pathogens. It may also be useful in engineering crops that produce specific gene products in the companion cells to block long-distance movement of pathogens. Received February 5, 2002; accepted March 27, 2002; published online July 4, 2002 RID="*" ID="*" Correspondence and reprints: Department of Plant Biology and Plant Biotechnology Center, 207 Rightmire Hall, Ohio State University, 1060 Carmack Road, Columbus, OH 43210, U.S.A.     

Insertional mutagenesis of a fungal biocontrol agent led to discovery of a rare cellobiose lipid with antifungal activity

Insertional mutagenesis was applied for the first time to a fungal biocontrol agent, Pseudozyma flocculosa, in an attempt to obtain mutants with altered antagonistic properties. Transformants were obtained via DNA-mediated transformation. Molecular analyses of the transformants revealed that multiple copies of the plasmid were integrated in tandem at one to many chromosomal loci. The transformants were screened for their biocontrol properties using standard bioassays, and the 160 tested transformants were classified into four groups: group I mutants (22 transformants) showed a stronger antagonistic effect than the wild type (WT) while those of group II (107 transformants) had a comparable antagonistic effect; group III mutants (17 transformants) had a decreased antagonistic effect relative to WT and group IV mutants (14 transformants) had lost their biocontrol properties. Culture extracts of the mutants (group IV) and WT were analyzed and compared for the presence of active metabolites which were then separated by solid-phase extraction and purified using conventional methods. Nuclear magnetic resonance experiments and analytical studies on a metabolite specifically produced by the WT revealed the presence of 2-(2',4'-diacetoxy-5'-carboxy-pentanoyl) octadecyl cellobioside (flocculosin), a novel glycolipid with strong antifungal properties; the production of this compound would account for the biocontrol activity of P. flocculosa.     

一种新的以细胞表面受体为靶向的基因导入系统

鉴于胰岛素样生长因子Ⅰ号及Ⅱ号的受体 (IGFⅠR ,IGFⅡR)在人原发性肝癌中过量表达 ,以及表皮细胞生长因子受体 (EGFR)在多种人恶性肿瘤过量表达 ,设计和合成了针对IGFⅠR及IGFⅡR的 1 4肽E5和针对EGFR的 1 6肽GE7,以及流感病毒血凝素功能域 2 0肽HA2 0作为内吞小体释放寡肽 (Endosomereleasingoligopeptide,EOP) ,将它们分别与多聚阳离子多肽 (Polycationic polypeptide ,PCP)———多聚赖氨酸 (Polylysine ,PL)或鱼精蛋白 (Protamine,PA)共价连接 ,藉静电效应与DNA形成一个复合体 (E5 PCP/DNA/PCP HA2 0 ,GE7 PCP/DNA/PCP HA2 0 ) ,即构建的新的受体介导的靶向性非病毒型基因导入系统 .体内、外实验结果表明它们相对靶向且高效地将外源基因导入人恶性肿瘤细胞并得到预期表达     

不同粒径口蹄疫病毒样颗粒-ZIF-8复合物诱导小鼠的体液免疫效果分析

为进一步提高口蹄疫(foot-and-mouthdisease,FMD)病毒样颗粒(virus-likeparticles,VLPs)疫苗的免疫效果，本研究采用仿生矿化方法，将Zn2+和2-甲基咪唑按照不同浓度配比制备了不同粒径的FMDV VLPs-沸石咪唑骨架-8 (zeolitic imidazolate framework-8, ZIF-8)复合物，以探究尺寸效应对免疫效果的影响。结果显示，成功制备出3种不同粒径的FMDV VLPs-ZIF-8，粒径分别约为70、100、1 000 nm。细胞毒性和组织病理学试验表明，3种复合物均具有良好的生物安全性。小鼠免疫试验表明，3种复合物均能明显提高中和抗体和特异性抗体水平，并且随着复合物体积的减小，其免疫效果也随之增强。本研究表明，ZIF-8包封FMDV VLPs可显著增强其免疫效果，且具有尺寸依赖性。