环状RNA的研究进展

环状RNA(circular RNA,circ RNA)是广泛存在于各种生物体中一类区别于传统线性RNA的新型形式,是特殊的内源性RNA分子,并具有调控基因表达的作用。circ RNA首次在RNA病毒中被发现。近年来,研究人员在人、鼠、线虫、植物、古生菌生物体内发现存在大量circ RNA。在真核生物体中,大部分circ RNA是由外显子构成,富集在胞浆中,并具有牢固的环状结构,大量存在于真核转录组中,具有良好的物种保守性以及组织特异性,不易被核酸酶裂解。研究发现,circ RNA可作为一类新型的竞争性内源RNA分子(competing endogenous RNA,ce RNA)调节物,发挥RNA海绵功能,竞争性抑制micro RNA(mi RNA)的表达,阻断mi RNA对其靶基因表达的抑制作用。目前发现,circ RNA在肿瘤、阿兹海默症等疾病的发生上起重要作用,其作为新型临床诊断标记物具有明显的优势。本文就circ RNA的研究进展作一综述。     

RNA聚合酶Ⅱ转录的ALU对PKR磷酸化的调节作用

目的研究ALU自身的RNA聚合酶Ⅲ启动子对RNA聚合酶Ⅱ转录的影响,探讨RNA聚合酶Ⅱ转录的ALU对PKR磷酸化的调节作用。方法将ALU全基因序列插入pcDNA3.1(-)载体的CMV启动子(一个RNA聚合酶Ⅱ启动子)的下游,构建重组质粒pcDNA3.1-ALU;转染HEK293细胞,提取细胞总RNA,RT-PCR筛选稳定表达ALU的细胞;用干扰素处理稳定表达ALU序列的细胞,Western blot法检测PKR的磷酸化水平。结果ALU全基因序列插入pcDNA3.1载体的CMV启动子直接下游,能够被RNA聚合酶Ⅱ有效转录;在稳定表达ALU的HEK293细胞中,加干扰素与未加干扰素组PKR的磷酸化水平均明显高于相应的HEK293细胞对照组。结论ALU自身的RNA聚合酶Ⅲ启动子对RNA聚合酶Ⅱ转录无明显影响,但与RNA聚合酶Ⅲ启动下转录的ALU不同,RNA聚合酶Ⅱ转录的ALU失去了对干扰素的拮抗作用,反而可以通过形成双链RNA的方式激活PKR的活性。     

苏木精染色对冰冻切片组织RNA及蛋白质浓度和质量的影响

目的探讨苏木精染色对冰冻切片组织RNA及蛋白质浓度和质量的影响。方法将10份乳腺癌组织冰冻切片进行苏木精染色以及苏木精染色后酸洗处理,利用显微切割技术从冰冻切片中获取特定乳腺癌细胞,Trizol提取相应的RNA及总蛋白,琼脂糖凝胶电泳和RT-PCR分析RNA质量,SDS-PAGE和Bandscan软件分析蛋白质电泳结果,并进行RNA和蛋白质的浓度测定。结果从10份乳腺癌组织冰冻切片中提取的RNA经琼脂糖凝胶电泳检测,苏木精染色组和苏木精染色后酸洗组的28S、18S、5S条带均有不同程度的降解,RT-PCR结果显示,RNA完整性较好;提取的蛋白电泳图谱处理前后无明显差异;苏木精染色以及苏木精染色后酸洗处理对乳腺癌组织中的RNA及蛋白质浓度无显著影响。结论苏木精染色对乳腺癌冰冻切片组织中RNA及蛋白质浓度和质量无显著影响,为肿瘤蛋白质组学的进一步研究提供了理论支持。     

RNA干扰抗乙肝病毒的研究进展

乙型肝炎病毒导致的慢性感染、肝炎、肝硬化和肝癌已经成为威胁全球健康的主要问题之一。至今,还没有找到能够彻底治愈慢性乙肝的特效药。RNA干扰(RNAi)研究快速发展,已被广泛用于基因功能研究和疾病治疗。阐述了小干扰RNA(siRNA)和微小RNA(miRNA)抗HBV的研究进展。     

DEAD-box RNA解旋酶3在肿瘤中作用机制的研究进展

DEAD-box RNA解旋酶(DEAD-box helicase,DDX)在RNA代谢过程中发挥多种功能,对转录、剪切、mRNA转出、翻译、核糖体合成及miRNA的调控均有一定影响,其对RNA代谢的影响可引起一系列疾病的产生。DEAD-box RNA解旋酶3(DDX3)是DDX家族重要的成员,在细胞周期阻滞、细胞增殖和凋亡中起重要作用。DDX3可在多种肿瘤组织中发生异常表达,影响肿瘤患者的生存和预后。本文就DDX3在肿瘤,如肺癌、结直肠癌、乳腺癌及肝癌中作用机制的研究进展作一综述。     

RNA保护剂对乳腺癌组织DNA及核蛋白丰度和质量的影响

目的探讨RNA保护剂对乳腺癌组织DNA及核蛋白丰度和质量的影响,为深入研究乳腺癌基因转录调控奠定基础。方法将临床摘除的乳腺癌新鲜组织放入RNA保护剂内浸泡过夜后,分别于-20℃保存及-80℃超低温冷冻保存。提取相应的DNA及核蛋白,进行浓度测定,通过琼脂糖凝胶电泳检测DNA的质量,SDS-PAGE检测核蛋白的质量,并经Bandscan软件分析蛋白质电泳结果。结果经RNA保护剂处理的乳腺癌组织提取的DNA和核蛋白的浓度明显高于-80℃超低温冷冻保存组织提取的DNA和核蛋白浓度,两种保护剂保存的乳腺癌组织提取的DNA浓度差异无显著意义。但RNA保护剂处理组与-80℃超低温冷冻处理组相比,在相对分子质量66200和31000处的蛋白含量有明显差异。结论RNA保护剂对乳腺癌组织的DNA浓度及核蛋白的浓度和质量有明显影响。     

RNA干扰技术对MCF-7细胞Aurora-A基因表达的影响

目的构建针对Aurora-A基因的特异性小干扰RNA(siRNA)真核表达载体,并探讨其对人乳腺癌细胞株MCF-7中Aurora-A基因表达的抑制作用。方法将具有短发夹结构的2条DNA序列,经退火形成互补双链,再克隆至载体pGCsi-U6/Neo/GFP中,转化大肠杆菌DH5α,提取质粒进行序列测定。并通过脂质体法转染至MCF-7细胞中,48h后观察转染效率,并采用RT-PCR及Westernblot法检测siRNA对MCF-7细胞Aurora-A基因mRNA及蛋白表达的影响。结果测序鉴定证实目的寡核苷酸片段已被克隆至pGCsi-U6/Neo/GFP载体中,Aurora-A-siRNA质粒转染MCF-7细胞48h后转染效率约为60%,与对照组比较,Aurora-A-siRNA质粒转染的细胞Aurora-A基因mRNA和蛋白的表达均明显下降。结论已成功构建了Aurora-A-siRNA真核表达质粒,其能明显抑制MCF-7细胞Aurora-A基因的表达,为进一步研究Aurora-A基因的功能奠定了基础,并可能为肿瘤的生物学治疗提供新的方法。     

肝细胞RNA在小鼠体内的抗突变作用

以 C_(57)BL/6J 小鼠为模型,皮下注射人肝或牛肝 RNA,4小时以后腹腔注射 MMC,,同时皮下埋植 5-溴尿嘧啶,再经24小时后取骨髓细胞进行姐妹染色单体交换及染色体畸变数检测;同时取 C_(57)BL/6J 雄性小鼠皮下注射人肝 RNA,4小时后腹腔注射 MMS,17天后,检测非程序 DNA 合成反应。结果表明肝 RNA 对 MMC 诱发的小鼠骨髓细胞姐妹染色单体交换和染色体畸变数,对 MMS 诱发非程序 DNA合成反应均具有明显的抑制作用。以上结果提示人肝及牛肝 RNA 对 MMC 或 MMS 所诱发的基因突变具有防护作用。     

利用卫星RNA保护植物

卫星 RNA 是一类与某些植物 RNA 病毒的一些株系相关的 RNA,但它们对于病毒的复制来说并非必需。卫星 RNA 在那些遭到它所依赖的病毒感染的细胞中复制,由于它与病毒基因组 RNA 一道包裹在病毒颗粒之中,所以可随病毒一同从病株组织中释放至新的感染部位。虽然卫星 RNA 的复制和转移完全依赖于病毒,但是其核苷酸序列却与病毒基因组的核苷酸序列全然不同(植物基因组通常由一种以上的 RNA 组成)。为什么自然选择的过程没有导致卫星 RNA 的丧失或排除的原因尚不清楚,但是,某些卫星 RNA 在其存在时能减轻、有时可以显著减轻病毒感染引起的病症的严重程度这一点,却是很清楚的。     

RNA药物研发进程

一、RNA药物市场分析目前，诺华、默克、OPKO健康、Alnylam制药等大型制药公司和生物科技企业正一掷千金，开发另一个生物技术领域的“潜力股”——RNA药物。从研究和开发传统生物制品的角度来看，大多数大型制药企业还不能和安进、基因泰克和BiogenIdec公司竞争。但考虑到RNA疗法具有”重磅炸弹”药物的潜力，过去的两年间，制药企业和生物企业之间围绕RNA干扰、反义RNA和适体等产品而产生了许多战略和金融上的交易。     

Quantification of Phospholipids Classes in Human Milk

Phospholipids are integral constituents of the milk fat globule membranes and they play a central role in infants’ immune and inflammatory responses. A methodology employing liquid chromatography coupled with evaporative light scattering detector has been optimized and validated to quantify the major phospholipids classes in human milk. Phospholipids were extracted using chloroform and methanol and separated on C18 column. Repeatability, intermediate reproducibility, and recovery values were calculated and a large sample set of human milk analyzed. In human milk, phospholipid classes were quantified at concentrations of 0.6 mg/100 g for phosphatidylinositol; 4.2 mg/100 g for phosphatidylethanolamine, 0.4 mg/100 g for phosphatidylserine, 2.8 mg/100 g for phosphatidylcholine, and 4.6 mg/100 g for sphingomyelin. Their relative standard deviation of repeatability and intermediate reproducibility values ranging between 0.8 and 13.4 % and between 2.4 and 25.7 %, respectively. The recovery values ranged between 67 and 112 %. Finally, the validated method was used to quantify phospholipid classes in human milk collected from 50 volunteers 4 weeks postpartum providing absolute content of these lipids in a relatively large cohort. The average content of total phospholipids was 23.8 mg/100 g that corresponds to an estimated mean intake of 140 mg phospholipids/day in a 4-week old infant when exclusively breast-fed.     

The hydration of reactive cement-in-polymer dispersions studied by nuclear magnetic resonance

The behaviour of two novel cement-in-polymer (c/p) dispersions, namely cement-in-poly(vinyl acetate) and cement-in-poly(vinyl alcohol) upon exposure to water at room temperature was investigated by a combination of various NMR methods. The swelling, cracking, and the water ingress were monitored non-destructively using ¹H single point imaging. The hydration of the cement matrix was investigated using ²⁹Si NMR whilst ¹³C CPMAS NMR spectra allowed the quantification of the kinetics of the hydrolysis reaction of poly(vinyl acetate) into poly(vinyl alcohol). The polymer controls the rate of water ingress and swelling which in turn determines the behaviour of the c/p dispersions upon exposure to water. For the cement-in-poly(vinyl alcohol), the rates of water ingress and swelling are much faster than the hydration of the clinker whilst for the cement-in-poly(vinyl acetate) the slow rates of the two processes allow the formation of a cementious matrix which assures the stability of the sample.     

Interactions between shrinkage reducing admixtures (SRA) and cement paste's pore solution

Shrinkage reducing admixtures (SRA) have been developed to combat shrinkage cracking in concrete elements. While SRA has been shown to have significant benefits in reducing the magnitude of drying and autogenous shrinkage, it has been reported that SRA may cause a negative side effect as it reduces the rate of cement hydration and strength development in concrete. To examine the influence of SRA on cement hydration, this study explores the interactions between SRA and cement paste's pore solution. It is described that SRA is mainly composed of amphiphilic (i.e., surfactant) molecules that when added to an aqueous solution, accumulate at the solution-air interface and can significantly reduce the interfacial tension. However, these surfactants can also self-aggregate in the bulk solution (i.e., micellation) and this may limit the surface tension reduction capacity of SRA. In synthetic pore solutions, SRA is observed to form an oil-water-surfactant emulsion that may or may not be stable. Specifically, at concentrations above a critical threshold, the mixture of SRA and pore fluid is unstable and can separate into two distinct phases (an SRA-rich phase and an SRA-dilute phase). Further, chemical analysis of extracted pore solutions shows that addition of SRA to the mixing water depresses the dissolution of alkalis in the pore fluid. This results in a pore fluid with lower alkalinity which causes a reduction in the rate of cement hydration. This may explain why concrete containing SRA shows a delayed setting and a slower strength development.     

Design and function of novel superplasticizers for more durable high performance concrete (superplast project)

In this article we shall describe our quest and ultimate success in furthering our understanding of the action of superplasticizers on the rheology of cement and concrete. By specifically producing superplasticizers with varied architectures, we have been able to show the important structural features of the macromolecules that lead to a successful superplasticizer or water reducing agent. Both polycarboxylate and lignosulfonate polymers have been investigated. Using both non-reactive model MgO powders, three different types of cement blends, the adsorption behaviour and the effect on the rheological properties of these two important superplasticizer families have been used to further develop a conceptual model for superplasticizer — cement behaviour. This paper will deal mainly with the conceptual model, the materials and methods used to asses the polymer adsorption behaviour and rheological properties of the systems studied. We shall briefly describe the adsorption of the polymers onto the different surfaces and their influence on surface charge and rheology and the influence of the various ionic species found in cement pore solutions that may influence polymer-cement affinity. The key factors are shown to be the effective adsorbed polymer thickness and the induced surface charge which can be influenced by the polymer architecture, the pore solution composition and the initial particle surface charge.     

Study of the hydration of CaO powder by gas–solid reaction

Hydration of CaO powders by reaction with water vapor has been studied in isothermal and isobaric conditions. Experimental tests were performed within the temperature range of 70 °C–420 °C and with a water vapor pressure from 5 to 160 hPa by means of a thermogravimetric device. Two powders, exhibiting slight differences in their physical properties, were studied. However, for one of the powders and under some temperature and pressure conditions, the reaction is not complete. The difference of behavior between both CaO powders was interpreted by considering the effect of the morphological properties on the mechanism of growth of Ca(OH)₂.     

The influence of water removal techniques on the composition and microstructure of hardened cement pastes

The removal of water from hardened cement paste for analysis or to arrest ongoing hydration has been reported to affect the composition of hydrated phases and microstructure. The effect that arresting the hydration of hardened cement paste by replacing the pore water with acetone before drying, and by removing the water by freeze, vacuum and oven drying has on the hardened cement paste has been investigated. Two pastes were studied, a cemented iron hydroxide floc where a high proportion of ordinary Portland cement (OPC) had been replaced by pulverised fuel ash, and a pure hydrated OPC. The results showed that none of the water removal techniques caused any major deterioration in the composition and microstructure of the hardened cement pastes studied, but the pores appeared better preserved after arresting hydration using acetone quenching. Freeze drying appeared to cause more cracking of the microstructure than the other water removal techniques.     

2-(2'-咪唑偶氮)萘酚-4-磺酸的合成及其分析性质的研究

合成了新显色剂咪唑偶氮－２－萘酚－４－磺酸（ＩＡＮ－４Ｓ）,研究了试剂的离解常数及其与金属离子的显色反应。     

Influence of bleed water reabsorption on cement paste autogenous deformation

The effects of bleed water reabsorption and subsequent early age expansion on observed autogenous deformation are investigated in this research. Bleeding was induced by varying superplasticizer and shrinkage-reducing admixture dosages and by increasing the water-to-cement ratio. This research revealed that significant early age expansion occurs with increasing chemical admixture dosages and higher water-to-cement ratios, as expected, due to increasing bleeding of those samples. When samples were rotated, negligible early age expansion was observed. Thus, bleed water reabsorption is shown to be the primary mechanism causing initial expansion in sealed autogenous deformation samples. Thermal dilation and ettringite growth appear to have a minimal influence on the observed expansion. Rotating the samples during setting eliminates the potential for bleed water reabsorption and is recommended for all autogenous deformation testing.     

Comparison between surface and bulk hydrophobic treatment against corrosion of galvanized reinforcing steel in concrete

The effectiveness of bulk hydrophobic treatment against corrosion of galvanized steel reinforcement in concrete specimens with w/c = 0.45 and w/c = 0.75 was compared with that of surface treatment, even in the presence of cracks 0.5 and 1 mm wide in the concrete cover. In this case surface hydrophobic treatments were applied both before and after cracking as a preventive and a restorative method against reinforced concrete deterioration, respectively. The obtained results in terms of water absorption, electrochemical measurements, chlorides penetration, and visual observations carried out on reinforced concrete specimens during the exposure to wet–dry cycles in 10% NaCl solution showed that bulk hydrophobization is the most effective treatment in improving the corrosion resistance of galvanized steel reinforcements in concrete also in the presence of cracks. Surface hydrophobization is very effective just in the first few exposure cycles to the aggressive environment and when used as a restorative method which is able to cancel the deleterious effect of cracks only 0.5 mm wide.     

Effect of plasma treatment of polymeric tape carriers on wetting behaviour of aqueous ceramic tape casting slurry

Due to environmental and health aspects, aqueous ceramic slurries are preferred to traditional organic solvent systems in tape casting. An important obstacle associated with the high surface energy of water is poor wetting of aqueous ceramic slurries on polymeric tape carriers. Therefore, we measured the contact angles of an aqueous epoxy-based ceramic slurry on polyethylene terephtalate (PET), polypropylene (PP), polymethyl methacrylate (PMMA), and aluminium-coated polyethylene terephtalate (PET-Al) films and investigated approaches to improving their wetting. We evaluated the effect of plasma treatment of the tape carrier surface on the wetting behaviour and compared it with the effect of adding non-ionic amphiphilic surfactants to the ceramic slurry. The treatment of the tape carrier surface by low-temperature plasma substantially improved the wetting behaviour of aqueous ceramic slurry. The lowest contact angle of 31° was obtained on the PET film. Although the addition of non-ionic surfactants improved both the wetting behaviour of the slurry and the detachment of the polymeric carrier from the ceramic tape even better than the plasma treatment of the carrier surface did, the plasma-treated carriers still present a useful alternative to the surfactants. In the case of the plasma-treated PET carrier the surfactants could be fully eliminated and potential drawbacks related to the use of surfactants could be prevented.