通过G418处理离体纯化小鼠胰腺上皮细胞

目的：探索一种能有效去除成纤维细胞,筛选有较强增殖能力上皮细胞的方法。方法：本研究利用成纤维细胞对G418敏感的特性,在成体小鼠胰腺细胞分离后,采用悬浮细胞直接接种到含30μg/mL G418的培养基中,或细胞贴壁生长汇合至50-70%后用30至100μg/mL之间不同浓度G418处理24h、48h或72h两种方案进行上皮细胞的纯化。结果：在直接接种法培养处理中,存活的大部分细胞为成纤维细胞,上皮细胞的生长受到抑制,无法得到纯化的胰腺上皮集落;而在细胞贴壁生长汇合至50-70%后经G418处理,成纤维细胞随着处理浓度的增加死亡率也在逐渐上升,其中50μg/mL G418处理72小时对去除成纤维细胞效果最佳。结论：G418处理能够有效去除成纤维细胞,分离纯化出一群在离体条件下具有强增殖能力、形成大上皮细胞集落的细胞。该分离纯化方法为今后进一步研究成体胰腺干/祖细胞增殖与分化调控机制等问题奠定基础。     

通过整体消化法分离具有集落形成能力的胰腺上皮样细胞

目的:胰腺上皮细胞能诱导成表达胰岛素的细胞,成为细胞替代疗法治疗糖尿病的重要来源。胰腺细胞的分离多采用机械剪切后胶原酶消化,本文在以往研究基础上,探索一种能分离得到更纯净的胰腺上皮样细胞的新方法。方法:本研究采用胰腺整体消化的方法,将成体小鼠整个胰腺取下,摘除系膜及大的血管,置于胶原酶中消化20min,用PBS吹打胰腺组织,得到的细胞悬液,离心后去除上清与细胞碎片,用培养基重悬实质细胞,接种于6 cm培养皿中,培养7-10天后得到单细胞集落。结果:整体消化法不剪碎胰腺组织,从而避免多种胰腺细胞的参与,得到较为纯净的胰腺上皮细胞悬液,细胞总体数量小于部分消化法,但是单细胞比率远远高于部分消化法,得到的细胞集落更纯净,不需要去除成纤维细胞,方便筛选及进一步扩大培养。结论:整体消化法能够分离纯化出一群在离体条件下具有强增殖能力、形成大的上皮样集落的细胞。该分离方法方便、快捷,为今后进一步研究成体胰腺干细胞增殖与分化调控机制等问题奠定基础。     

绵羊皮肤成纤维细胞对G418及Blasticidin S抗性的研究

抗生素常被用于对转基因动物、植物及微生物细胞进行筛选。在进行抗生素抗性筛选前,需要摸索合适的抗生素使用浓度,其原因在于:过低的筛选浓度无法抑制非转基因细胞的生长;反之,过高的筛选浓度会导致转基因细胞死亡。为了摸索绵羊皮肤成纤维细胞(sheep skin fibroblasts, SSFs)对G418及Blasticidin S的抗性,本实验以体外培养的SSFs为实验材料,采用不同浓度的上述两种抗生素处理SSFs,采用活细胞计数的方式检测SSFs对上述两种抗生素的抗性。单独使用G418或Blasticidin S导致SSFs全部死亡的最低致死浓度分别为200μg/mL及4μg/mL;当两种抗生素联合使用时,其最低致死浓度为100μg/mL G418+3μg/mL Blasticidin S或150μg/mL G418+2μg/mL Blasticidin S。该实验为采用这两种抗生素筛选转基因SSFs提供了理论基础。     

用饲养层分离胚胎干细胞集落的实验初探

目的 用饲养层分离胚胎干细胞集落。方法 用胚龄为13~14 d的小鼠胚胎分离原代成纤维细胞,制成饲养层,用于囊胚的培养。结果 小鼠原代胚胎成纤维细胞（PMEF）贴壁能力较好,增殖快,易铺层。囊胚和内细胞团（ICM）在饲养层上贴壁生长良好,当培养4~5 d时,其增殖率为16/28（57%）。在ICM离散48 h后,各种胚胎干细胞（ES）集落开始出现。此种集落经碱性磷酸酶染色成阳性。结论 用饲养层分离胚胎干细胞获得初步成功。     

牛成纤维细胞的分离与体外培养

研究了牛胎儿和成年牛皮肤组织成纤维细胞的分离、培养、纯化方法和生长特征。通过组织块贴壁培养和分离单细胞接种培养均能获得原代牛皮肤细胞。用2.5 g/L胰蛋白酶+1mmol/L EDTA和5 g/L胶原酶I联合消化牛皮肤组织较2.5 g/L胰蛋白酶+1 mmol/L EDTA消化,得到更多的单个细胞,两者之间差异极显著(P<0.01),但其死细胞比率却有较大升高;2.5 g/L胰蛋白酶+1 mmol/L EDTA消化牛胎儿组织得到的单细胞数显著高于皮肤组织消化后得到的细胞数(P<0.01),死细胞比率也高于同种酶消化的皮肤组织。分离纯化的胎儿和皮肤成纤维细胞的生长曲线都正常且相似。2.5 g/L胰蛋白酶+1 mmol/L EDTA消化贴壁细胞后死细胞率明显高于用0.5g/L胰蛋白酶+0.53 mmol/L EDTA消化的细胞(P<0.05);培养24 h后细胞贴壁率前者要明显低于后者(P<0.05)。用0.5 g/L胰蛋白酶轻度消化混杂生长的成纤维细胞和上皮样细胞,经过反复贴壁传代2～3代,可得到较纯的成纤维细胞。     

新疆家蚕抗菌肽体外抑制人胃癌细胞AGS的增殖

新疆家蚕抗菌肽(Cecropin XJ)具有抑制肿瘤细胞生长的能力。为研究不同浓度Cecropin XJ体外对人胃癌细胞AGS生长的影响,分别采用MTT比色法、软琼脂集落形成实验、流式细胞术、划痕愈合和Transwell实验进行检测。结果表明,20~100μg/mL的Cecropin XJ能够显著抑制AGS细胞的增殖,并具有剂量和时间依赖性。同时,20,50,100μg/mL的Cecropin XJ处理后集落形成率分别降低了(35.81±13.10)%、(48.12±5.68)%和(81.46±6.21)%。AGS细胞经不同浓度Cecropin XJ处理24 h后,凋亡率逐渐上升并且细胞周期阻滞于S期。20μg/mL Cecropin XJ能够显著抑制AGS细胞的迁移和侵袭,100μg/mL Cecropin XJ几乎完全抑制AGS细胞的迁移和侵袭。以上结果说明,Cecropin XJ能够抑制AGS细胞生长、增殖,有可能成为人胃癌治疗的辅助药物。     

人脐带和骨髓间充质干细胞体外分离培养及生物学特性比较

目的体外分离培养、扩增人脐带间充质干细胞(h UC-MSC)和人骨髓间充质干细胞(h BM-MSC),并对其生物学特性进行比较。方法采用组织块贴壁法从足月胎儿脐带分离、纯化和培养h UC-MSC,健康成人骨髓肝素抗凝后,采用密度梯度离心法分离、纯化和培养h BM-MSC;用倒置显微镜观察两种细胞的形态及细胞生长增殖情况,流式细胞仪分析检测第3代细胞表面标志的表达,Von?Kossa染色及油红O染色检测分化潜能。结果镜下两种细胞均为贴壁生长,形态为均一的成纤维细胞样,取相同数量的细胞传代接种后,h UC-MSC的增殖速率快于h BM-MSC,两种细胞具有均一的细胞表型,均表达CD29、CD44、CD105,不表达CD45、CD34、HLA-DR、HLA-G、CD80、CD86,两种细胞都有成骨、成脂分化潜能,但h UC-MSC的分化潜能更强。结论 h UC-MSC与h BM-MSC具有相似的生物学特性,且前者具有更强的增殖能力和分化潜能,h UC-MSC有望成为h BMMSC理想的替代来源。     

血竭素高氯酸盐在调节成纤维细胞的增殖和创面愈合中的作用

高氯酸血竭素(dracorhodin perchlorate, DP)是一种具有多种药理活性的天然药物,本研究旨在揭示血竭素高氯酸盐在调节成纤维细胞的增殖和创面愈合中的作用。本研究显示,DP处理促进NIH/3T3成纤维细胞增殖,并促进体外和体内的伤口愈合。DP处理24 h显著诱导成纤维细胞增殖,这与磷酸化细胞外信号调节激酶(ERK)水平增加有关。ERK用siRNA阻断则可降低成纤维细胞的增殖。与对照组相比,在大鼠体内应用2.5μg/mL、5μg/mL和10μg/mL剂量的DP可促进大鼠伤口愈合。DP处理7 d后,Serpin家族H成员1 (SERPINH1)染色证实创面组织中成纤维细胞增殖升高。因此,DP可促进体外培养的成纤维细胞的增殖,并诱导大鼠体内伤口愈合。     

昆明小鼠胚胎干细胞滋养层制备条件的实验研究

目的:建立小鼠胚胎成纤维细胞(MEFS)滋养层,用于昆明小鼠胚胎干细胞的培养。方法:取妊娠13.5的胎鼠,采用组织消化法分离培养出原代成纤维细胞,对MEFs的生长形态、生长曲线及分裂指数进行观察;MTT法筛选丝裂霉素C(MMC)作用的最佳浓度和时间;取妊娠3.5d的囊胚在经MMC处理的饲养层上培养,观察胚胎干细胞集落生成情况。结果:MEFS为一种贴壁生长且增殖速度较快的细胞,第三代细胞增殖旺盛,第5代以后细胞开始变形并趋于衰老;MMC能抑制胚胎成纤维细胞的增殖,最佳的作用浓度和时间是10ug/ml作用2.5～4h,20ug/ml作用1-2.5h。妊娠3.5d小鼠囊胚在饲养层上培养能形成典型的"鸟巢"状干细胞集落,并可维持胚胎干细胞的正常形态且不发生分化。结论:这种方法制备的滋养细胞层适用于胚胎干细胞的培养。     

中华鼢鼠成纤维细胞长期培养及其生物学特性分析

中华鼢鼠(Eospalax fontanierii)为蒙古高原代表性动物遗传资源,本研究采集中华鼢鼠心、肝、脾、肺、肾、肌肉、气管、剑状软骨和尾尖皮肤共9种组织用于实验,其中气管、肺和剑状软骨3种组织成功建立成纤维细胞系,传了8代,并分析了这些细胞的生物学特性。主要实验方法是通过细胞计数法计算细胞的贴壁率、冻存前及复苏后的存活率、绘制细胞生长曲线;制备常规染色体标本分析染色体核型。实验结果显示,中华鼢鼠气管、肺、软骨3种组织在体外条件下培养,第3～4天出现成纤维样细胞,原代细胞分别在培养第11天、第16天、第17天,达到90%以上汇合。3种组织来源体细胞均显示成纤维细胞特征,气管成纤维细胞贴壁能力最强,24 h贴壁率最高能达到98.10%,肺成纤维细胞与剑状软骨成纤维细胞贴壁能力较弱,24 h贴壁率最高,分别为95.28%和94.88%。3种来源成纤维细胞生长曲线测定结果显示,气管成纤维细胞的增殖能力最强、肺成纤维细胞次之、剑状软骨成纤维细胞最弱。气管成纤维细胞和肺成纤维细胞在接种后的第6～7天,进入对数生长期。剑状软骨成纤维细胞在接种后第2～3天进入对数生长期。3种成纤维细胞的生长曲线均呈"S"型,其中气管成纤维细胞增殖能力最强,在24孔板的每个孔中,其最大增殖数目为2.435×10~4个,肺成纤维细胞最大增殖数目为1.813×10~4个,剑状软骨成纤维细胞最大增殖数目为1.521×10~4个。核型分析结果显示,中华鼢鼠的成纤维细胞染色体数目为2n=62,30对为常染色体,1对为性染色体。综上所述,本研究成功建立了中华鼢鼠成纤维细胞体外培养体系,并揭示了该物种成纤维细胞的基本生物学特性,为深入研究中华鼢鼠适应低氧高二氧化碳洞道生境的分子生物学和生理学机制提供了条件,为进一步研究其遗传及物种进化提供了实验材料和参考。     

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     

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.     

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.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

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).     

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.