内含肽介导的绿色荧光蛋白纯化

利用来源于蓝细菌Synechocystis sp.PCC6803的DnaB内含肽的剪切特性,纯化绿色荧光蛋白.在大肠杆菌中将内含肽与绿色荧光蛋白融合表达,绿色荧光蛋白融合于DnaB内含肤的C端,在20℃,pH 7.0的条件下诱导DnaB内含肤的自剪切发生,利用几丁质亲和柱纯化到无素和标签的绿色荧光蛋白,得到蛋白有较高的...     

Pre-unfolding resonant oscillations of single green fluorescent protein molecules

Fluorescence spectroscopy of a green fluorescent protein mutant at single-molecule resolution has revealed a remarkable oscillatory behavior that can also be driven by applied fields. We show that immediately before unfolding, several periodic oscillations among the chemical substates of the protein chromophore occur. We also show that applied alternating electric or acoustic fields, when tuned to the protein characteristic frequencies, give rise to strong resonance effects.     

绿色荧光蛋白基因标记芒果畸形病病原菌研究

芒果畸形病是世界性的芒果重要病害。采用PEG介导的原生质体转化法用绿色荧光蛋白(GFP)表达载体(pCT74-sGFP)转化芒果畸形病病原菌(Fusarium proliferatum),获得了表达GFP的转化子。转化子经过单孢纯化后连续继代培养仍能发出稳定而强烈的荧光,通过GFP特异性引物PCR扩增转化子基因组获得预期片段,表明GFP基因已成功转入芒果畸形病病原菌基因组中且稳定遗传。GFP标记菌株生长正常,致病性和野生菌丝无差别。获得GFP标记的转化子,为应用发绿色荧光的芒果畸形病病原菌研究病原菌的侵染方式、扩展过程等奠定了基础。     

表达绿色荧光蛋白重组单核细胞增多性李斯特菌的构建

将编码绿色荧光蛋白(GFP)的基因融合到单核细胞增多性李斯特菌actA基因启动子和信号肽下游,应用同源重组技术构建了含gfp的重组李斯特菌突变株.PCR扩增及其产物的酶切鉴定均证实目的基因gfp融合到李斯特菌基因组中.荧光显微镜下可见重组菌体发绿色荧光.SDS-PAGE电泳和免疫印迹结果显示重组李斯特菌表达的GFP分子量约为28 kD,与预计的分子量大小一致.重组菌对鸡胚和小鼠的毒力以及对体外培养细胞的侵袭力均低于野生型李斯特菌.该重组菌可用于研究李斯特菌的致病机理和食品加工过程中微生物污染控制的指示性细菌.     

绿色荧光蛋白基因标记枯草芽孢杆菌研究

将源于枯草芽孢杆菌168的木糖启动子xylR和来源于载体pGFPuv的gfp基因连接,插入枯草芽孢杆菌-大肠杆菌穿梭载体pIM,成功构建了以绿色荧光蛋白(GFP)为报告基因的重组载体pIM-GFP.转化枯草芽孢杆菌菌株BS523,突变株在荧光显微镜及紫外灯下均观察到较强的绿色荧光,同时PCR鉴定结果正确.表明重组载体pIM-GFP成功转入菌株BS523,并且gfp基因成功表达.     

表达绿色荧光蛋白的猪胚胎生殖细胞分离

以质粒DNA为增强型绿色荧光蛋白(EGFP)的载体，对处于快速增殖期的8株猪胚胎生殖(EG)细胞(4—9代)进行转基因试验。用1μg DNA和2μL LipofecTamine 2000转染EG细胞后，共获得4株转染EGFP基因的EG细胞系(EG—EGFP)，可发出强绿色荧光；EG—EGFP细胞连续培养2周以上可分化为多种细胞类型。显微注射EG—EGFP细胞至卵裂期胚胎、桑椹胚卵周隙内或囊胚腔中，共注射135枚胚胎，其中112枚存活并发育至囊胚(83．0％)；86枚嵌合体胚培养后含有荧光细胞，其中57枚囊胚在内细胞团(ICM)上发现有EG—EGFP细胞。     

A minirhizotron imaging system to identify roots expressing the green fluorescent protein

The limited flexibility available in the configuration of commercial minirhizotron imaging systems makes it difficult to adapt these systems to new applications. It is also too expensive to introduce modifications, which are often very temporary to these systems at the end of the development process.In order to identify the roots of a single species in mixed plant stands, we developed a new minirhizotron imaging system that makes it possible to observe roots expressing green fluorescent protein (GFP). This system is based on affordable and easily obtainable components such as webcams. Here, we report a protocol to identify suitable webcams for constructing a minirhizotron imaging system and demonstrate the application of this protocol to build a minirhizotron imaging system that can identify the roots of a transformed maize plant expressing GFP.     

雌激素调控的绿色荧光蛋白在酵母细胞中的表达

采用绿色荧光蛋白(GFP)作为报告基因,用酵母细胞构建环境雌激素(EEH)的评价体系,可敏感、快速、方便地筛选出EEH化合物。通过分子生物学技术,将GFP基因插入到pM P 206/ERE启动子CYC 1的下游,用GFP取代L ac Z基因,并转化于酵母细胞。DNA测序发现ERE-CYC 1-GFP框架正确。对转化子进行PCR鉴定,发现有雌激素受体基因(hER cDNA)和GFP基因特异条带,说明hER cDNA和GFP已重组于酵母细胞。荧光显微镜下发现大量的绿色荧光颗粒,表明GFP基因在酵母细胞中成功表达。酵母细胞经不同浓度雌二醇作用后,与GFP表达量有剂量效应关系。与其他酵母评价体系相比,以GFP为报告基因评价EEH不需要破坏细胞壁,也不需要底物,可在96孔板中完成,这为高通量筛选EEH化合物奠定了基础。     

斜卧青霉转录调控蛋白Hac1过表达菌株的构建

【目的】以增强型绿色荧光蛋白为报告基因,构建斜卧青霉转录调控蛋白Hac1激活形式基因(Hac1i)随机插入过表达菌株和非激活形式基因(Hac1u)原位插入过表达菌株,并初步观察Hac1基因的2种不同编码蛋白在菌丝内部的运动情况,为进一步研究转录调控蛋白Hac1的功能奠定基础。【方法】分别克隆ptrA筛选标记、gpdA启动子、Hac1i编码区、eGFP编码区及终止子,利用融合PCR融合克隆片段,构建Hac1i随机插入表达盒;再分别克隆Hac1上游臂及编码区、eGFP编码区及终止子、ptrA筛选标记、Hac1下游臂序列,融合克隆片段,构建Hac1u原位插入表达盒。将2种表达盒分别转化斜卧青霉原生质体,通过吡啶硫胺素筛选标记、PCR扩增等检测获得阳性转化子,荧光显微镜观察融合蛋白的表达及运动情况。【结果】成功构建了Hac1i基因随机插入表达盒和Hac1u基因原位插入表达盒,利用原生质体转化将2种表达盒转入宿主斜卧青霉菌株,经PCR初步验证,得到了阳性转化子。阳性转化子在麸皮培养基上培养2~4d后,可在菌丝内部清晰观察到强烈的绿色荧光信号,表明融合蛋白在菌丝体内得到了正确表达。【结论】成功构建了Hac1i基因随机插入和Hac1u基因原位插入菌株。     

表达绿色荧光蛋白重组乳酸杆菌的构建及电击转化条件

应用DNA重组技术构建了表达绿色荧光蛋白(GFP)的重组乳酸杆菌．将pGFP2质粒中的绿色荧光蛋白基因切下,克隆进表达载体质粒pThioHisB的NcoⅠ和SacⅠ位点之间,构建成重组表达质粒pThaioGFP,然后转化大肠杆菌B121．从BL21中提取重组质粒,用电击法转化乳酸杆菌Lac1001,当细菌处于D600nm为0．6的生长期时,使用PEB作为电击缓冲液,对100μL体积的细胞悬液在电容25μF,电阻200Ω,电压2．2kV的电击条件进行完整质粒转化可得到较高的转化率．电击转化后Lacl001于LB培养基上呈绿色,在荧光透射仪下观察,整个菌体发绿色荧光．构建的重组乳酸杆菌能够稳定表达绿色荧光蛋白．     

低能氩离子束介导将绿色荧光蛋白基因导入小麦的研究

用低能氩离子束介导将改良的绿色荧光蛋白基因（ｍＧＦＰ４）导入小麦栽培品种皖９２１０和皖麦３２号的成熟胚细胞。在含有１００￣１４０ｍ／Ｌ巴龙霉素培养基上继代培养后,获得了一批抗性愈伤组织。经过分化培养,皖９２１０获得５株再生苗,皖麦３２号获得３２株绿苗,对照的２００枚成熟胚未获得再生苗。对再生苗进行ＰＣＲ检测,均扩增出６００ｂｐ的ｎｐｔⅡ基因片段。取４株长势好的绿苗进行Ｓｏｕｔｈｅｒｎ杂交分析,结果     

重组小麦组蛋白H4介导绿色荧光蛋白基因(pEGFP/C1)的转染

利用在大肠杆菌体内表达的重组小麦组蛋白H4与质粒DNA形成复合体后,通过琼脂糖凝胶电泳迁移试验(EMSA)验证重组蛋白与DNA的结合情况;MTT法检测蛋白对细胞的毒性作用;转染细胞后,激光共聚焦显微镜检测荧光蛋白的表达。此重组蛋白能很好地结合质粒DNA,且能有效地保护DNA分子不受核酸酶降解,并能高效地携带绿色荧光蛋白基因pEGFP/C1转染进入卵巢癌细胞株H08910。     

A fluoroquinolone resistance protein from Mycobacterium tuberculosis that mimics DNA

Fluoroquinolones are gaining increasing importance in the treatment of tuberculosis. The expression of MfpA, a member of the pentapeptide repeat family of proteins from Mycobacterium tuberculosis, causes resistance to ciprofloxacin and sparfloxacin. This protein binds to DNA gyrase and inhibits its activity. Its three-dimensional structure reveals a fold, which we have named the right-handed quadrilateral beta helix, that exhibits size, shape, and electrostatic similarity to B-form DNA. This represents a form of DNA mimicry and explains both its inhibitory effect on DNA gyrase and fluoroquinolone resistance resulting from the protein's expression in vivo.     

Visfatin: a protein secreted by visceral fat that mimics the effects of insulin

Fat tissue produces a variety of secreted proteins (adipocytokines) with important roles in metabolism. We isolated a newly identified adipocytokine, visfatin, that is highly enriched in the visceral fat of both humans and mice and whose expression level in plasma increases during the development of obesity. Visfatin corresponds to a protein identified previously as pre-B cell colony-enhancing factor (PBEF), a 52-kilodalton cytokine expressed in lymphocytes. Visfatin exerted insulin-mimetic effects in cultured cells and lowered plasma glucose levels in mice. Mice heterozygous for a targeted mutation in the visfatin gene had modestly higher levels of plasma glucose relative to wild-type littermates. Surprisingly, visfatin binds to and activates the insulin receptor. Further study of visfatin's physiological role may lead to new insights into glucose homeostasis and/or new therapies for metabolic disorders such as diabetes.     

Probing protein electrostatics with a synthetic fluorescent amino acid

Electrostatics affect virtually all aspects of protein structure and activity and are particularly important in proteins whose primary function is to stabilize charge. Here we introduce a fluorescent amino acid, Aladan, which can probe the electrostatic character of a protein at multiple sites. Aladan is exceptionally sensitive to the polarity of its surroundings and can be incorporated site-selectively at buried and exposed sites, in both soluble and membrane proteins. Steady-state and time-resolved fluorescence measurements of Aladan residues at different buried and exposed sites in the B1 domain of protein G suggest that its interior is polar and heterogeneous.     

The fluorescent toolbox for assessing protein location and function

Advances in molecular biology, organic chemistry, and materials science have recently created several new classes of fluorescent probes for imaging in cell biology. Here we review the characteristic benefits and limitations of fluorescent probes to study proteins. The focus is on protein detection in live versus fixed cells: determination of protein expression, localization, activity state, and the possibility for combination of fluorescent light microscopy with electron microscopy. Small organic fluorescent dyes, nanocrystals ("quantum dots"), autofluorescent proteins, small genetic encoded tags that can be complexed with fluorochromes, and combinations of these probes are highlighted.     

Development and use of fluorescent protein markers in living cells

The ability to visualize, track, and quantify molecules and events in living cells with high spatial and temporal resolution is essential for understanding biological systems. Only recently has it become feasible to carry out these tasks due to the advent of fluorescent protein technology. Here, we trace the development of highly visible and minimally perturbing fluorescent proteins that, together with updated fluorescent imaging techniques, are providing unprecedented insights into the movement of proteins and their interactions with cellular components in living cells.