脂质体介导法转染肿瘤细胞效率的优化

目的:研究优化影响脂质体转染效率的因素,以提高脂质体转染效率,为相关研究和应用提供参考.方法:以绿色荧光蛋白(GFP)作为报告基因,采用脂质体Lipofectamine 2000包裹pU6H1-GFP-FAK重组质粒转染Caco-2细胞,研究了细胞接种密度、DNA用量、脂质体与DNA的比例、脂质体-DNA复合物的形成时间、细胞与脂质体复合物的孵育时间、血清的有无及细胞的传代次数等因素对脂质体转染效率的影响.结果:2-5次细胞传代,2×105接种密度、4μg DNA用量、2.5:1的脂质体与DNA比例、30min脂质体-DNA复合物形成时间以及6h细胞与复合物孵育时间,转染效率最高.血清在本实验室条件下并不影响转染效率.结论:实验获得的优化条件可以明显提高脂质体对肿瘤细胞的转染效率,可作为有关研究或应用的参考.     

影响非洲绿猴肾细胞脂质体转染效率的因素

已有实验表明,细胞转染效率可能决定于ＤＮＡ－脂质体复合物的形成以及所转染的细胞种类。利用脂质体ＬｉｐｏｆｅｃｔＡＭＩＮＥ,研究了影响Ｖｅｒｏ细胞转染效率的参数如ＤＮＡ和脂质体的用量,转染的细胞数量以及细胞暴露于ＤＮＡ－脂质体复合物的时间长度。通过检测报告基因β－半乳糖苷酶（β－ｇａｌ）的表达,发现最高转染率只在一较窄范围内获得。β－ｇａｌ的表达随脂质体量增加而显著增加。在标准转染条件下,增加ＤＮＡ用量和延长细胞暴露时间反而使转染效率下降。转染细胞数量为４×１０４细胞／２４孔时,细胞转染效率最高。     

影响非洲猴肾细胞脂质体转染效率的因素

已有实验表明,细胞转染效率可能决定于ＤＮＡ－脂质体复合物的形成以及所转染的细胞种类。利用脂质体ＬｉｐｏｆｅｃｔＡＭＩＮＥ,研究了影响Ｖｅｒｏ细胞转染效率的参数如ＤＮＡ和脂质体的用量,转染的细胞数量以及细胞暴露子ＤＮＡ－脂质体复合物的时间长度。通过检测报告基因β－半乳糖苷酶（β－ｇａｌ）的表达,发现最高转染率在一较窄范围内获得。β－ｇａｌ的表达随脂质体量增加而显著增加。在标准转染条件下,增加ＤＮＡ用     

优化脂质体对肝癌细胞株HepG2细胞转染效率

摸索用Lipofectamine 2000(Lipo)转染质粒pEGFP-C1到肝癌细胞HepG2较为合适的转染条件。以HepG2细胞为研究对象,采用脂质体Lipofectamine 2000转染pEGFP-C1质粒,在24孔板先按每孔0.5μg固定pEGFP-C1质粒用量,摸索Lipo在1μL、1.5μL、2μL、2.5μL量上较为合适的用量,确定Lipo用量后,然后固定Lipo为1μL,摸索质粒用量0.5μg、1μg,确定脂质体与质粒的最佳比例。此外,对转染中培养基是否含血清,Lipofectamine 2000与pEGFP-C1质粒比例为1:0.5的基础上,扩大用量,即Lipofectamine 2000 2μL和pEGFP-C1质粒1μg,以及脂质体复合物孵育细胞时间进行优化。最后,采用荧光倒置显微镜观察细胞转染效率和方差分析及秩和检验的统计学方法进行统计分析。结果显示,pEGFP-C1质粒固定为0.5μg时,Lipo用量在1μL及1.5μL用量组转染效率最好,之后随着Lipo用量加大,转染效率下降;固定Lipo用量1μL,pEGFP-C1质粒0.5μg时转染效率最好(p0.05),比例不变,扩大Lipo和质粒用量,并不增加转染效率。转染后于3 h、6 h、8 h、12 h、24 h换成正常培养基培养,转染6 h后换液较好。此外,研究发现培养基是否含血清不影响转染效率。本研究表明在24孔板板中用Lipofectamine 2000转染HepG2细胞时较为合适的转染条件为每孔1μL Lipofectamine 2000和0.5μg质粒,脂质体与质粒的最佳比例为2:1,血清不影响转染效率,用含血清培养基转染后6 h换液培养。     

小鼠骨样细胞MLO-Y4转染方法的研究

为了建立质粒转染小鼠骨样细胞MLO-Y4的方法,分别采用阳离子脂质体法和电转染法将增强型绿色荧光蛋白（EGFP）质粒pEGFP-C1转染小鼠骨样细胞MLO-Y4,正常培养48h后检测并统计转染率和死亡率。结果显示,脂质体法转染,当质粒与脂质体比例为1∶4时,转染效率可达到（36.8±3.7）%,细胞死亡率为（18.4±1.9）%;电转染法转染,脉冲电压240 V,脉冲时间300μs,脉冲次数3次时,转染率最高,可达到（23.8±2.3）%,细胞死亡率为（14.1±1.1）%。而后MTT实验显示脂质体转染法相对于电转染法对MLO-Y4细胞的增殖有一定的抑制作用,但对后续实验研究影响不大。脂质体转染法转染小鼠骨样细胞MLO-Y4优于电转染法。     

电穿孔法转染293T细胞条件的优化

为筛选电穿孔转染人胚肾293T细胞的最优条件,将增强型绿色荧光蛋白(EGFP)基因克隆至启动子p CMV前,获得的重组质粒在不同电压、质粒浓度和电击次数条件下电穿孔转染293T细胞,继而在倒置荧光显微镜下观察转染细胞,根据EGFP表达情况评价转染效率。结果表明400 V电压、45 mg质粒电穿孔转染293T细胞2次时转染效率达到44%,与脂质体转染效率(51%)无统计学差异。     

小鼠精原干细胞不同转染方法效率的比较

本研究采用腺病毒感染、慢病毒感染、脂质体转染和电穿孔转化方法将含有绿色荧光蛋白（GFP）的质粒转入经过差异贴壁法初步分离纯化的小鼠精原干细胞(SSCs)中,转染48 h后通过流式细胞仪检测GFP阳性细胞比例比较4种方法在体外转染精原干细胞的效率.结果显示,脂质体转染效率最高仅为8.64%,不能满足对精原干细胞进一步实验的要求;电穿孔法效率最高达到25.27%,但转化后细胞大量死亡;腺病毒转染细胞的效率达到了32.4%;慢病毒转染效率最高,达到74.25%. 因此,慢病毒转染法是体外转染小鼠精原干细胞的有效方法.     

小鼠KGF基因毛囊特异性表达载体的构建及mESC脂质体悬浮转染条件的优化

旨在构建小鼠角质细胞生长因子(KGF)真核表达载体pCDsR-UKA,通过脂质体转染法转染小鼠胚胎干细胞( mESC),并进一步优化其转染条件,最终获得可以正常生长并稳定表达红色荧光蛋白的转KGF基因的ES细胞.利用RTPCR技术扩增小鼠KGF基因cDNA并构建表达载体pCDsR-UKA (6.6 kb),经鉴定正确的重组质粒DNA用脂质体包裹后转染mESC.从小鼠成纤维细胞cDNA扩增出891 bp的KGF基因片段与UHS启动子和BGH polyA序列成功重组到pCDsRed2载体中.经酶切和DNA测序验证,插入载体的DNA片段为KGF基因且方向正确.采用脂质体法优化转染条件,mESC最高转染效率达到(34.4±4.1)％.经G418筛选的转基因ES细胞通过PCR鉴定证实外源基因已整合在ES细胞基因组中.成功获得了小鼠KGF基因片段,以及真核表达载体pCDsR-UKA,经优化的脂质体悬浮法转染条件,在六孔板中当DNA与脂质体比例为3:10时,可获得最佳转染效率且不改变ES细胞的生长状态,经筛选获得了转基因ES细胞克隆.为下一步通过四倍体补偿技术获得ES小鼠提供了转基因ES细胞.     

阳离子脂质体介导RNA干扰的效果评价

考察自制的肽型阳离子脂质体CDO14作为RNA转染载体的细胞毒性及其运载si RNA进行RNA干扰的效果。通过MTT法检测脂质体对稳定表达荧光素酶的肺癌A549(Luc-A549)细胞的毒性。以脂质体为载体将荧光素酶si RNA(Luc-si RNA)转染至Luc-A549细胞内,用发光仪检测转染细胞内荧光素酶含量,BCA法检测细胞内总蛋白含量。在裸鼠腋下接种Luc-A549细胞,成瘤后尾静脉注射Luc-si RNA和脂质体的复合物,利用活体成像系统检测模型小鼠体内荧光素酶的表达量。细胞毒性实验表明,自制脂质体的毒性与商品脂质体DOTAP相近,低于商品脂质体Lipo2000;细胞转染实验表明自制脂质体作为基因转染载体的转染效率高于DOTAP;体内转染实验表明CDO14作为载体转染效果优于DOTAP。结果表明,肽型阳离子脂质体CDO14具有毒性小、转染效率高等优点,有望作为转染载体用于基因治疗。     

脂质体介导基因编辑载体质粒转染条件的优化

[目的]探讨脂质体介导基因编辑载体质粒转染人食管癌Eca-109细胞的最佳条件。[方法]以基于Cre/Lox P系统的p GT-A1B1和基于CRISPR/Cas9系统的p X458-sgRNA8两种基因编辑载体质粒为实验材料,将环状和线性质粒以不同DNA用量(0. 2、0. 4、0. 6和0. 8μg)和不同DNA与脂质体比例(1∶1、1∶1. 5、1∶2、1∶2. 5和1∶3)转染Eca-109细胞,计算转染效率。[结果]不同DNA用量条件下,p GT-A1B1在0. 4μg和0. 6μg时转染效率较高,p X458-sgRNA8在0. 6μg时转染效率较高,与其它DNA用量比较均有显著性差异(P 0. 05)。不同DNA与脂质体比例条件下,p GT-A1B1在比例为1∶1. 5和1∶2时转染效率较高,p X458-sgRNA8在比例为1∶2. 5时转染效率较高,与其它比例比较均有显著性差异(P 0. 05)。同一种质粒的环状和线性结构形态,在DNA用量或DNA与脂质体比例相同时,转染效率差异不显著(P 0. 05)。[结论]建立了脂质体介导基因编辑载体质粒转染Eca-109细胞的最佳转染条件,质粒p GT-A1B1和p X458-sgRNA8的DNA用量分别为0. 4～0. 6μg和0. 6μg,DNA与脂质体比例分别为1∶1. 5～1∶2和1∶2. 5。     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

鸡传染性法氏囊病病毒研究进展

传染性法氏囊病(Infection bursal disease, IBD)是由鸡传染性法氏囊病毒(Infectious bursal disease virus, IBDV)引起的鸡和火鸡的一种高度接触性传染病,给世界各国的禽养殖业带来了巨大损失.自IBDV发现至今新的变异株不断出现,分子结构的改变导致病毒致病力的改变及宿主对疫苗应答的改变,使得传统的疫苗已不能控制其流行,因此各国学者对其基因组结构和功能进行了广泛深入的研究,并积极研制新型有效的疫苗以达到防治的目的.     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).