正交试验优化八角ISSR-PCR反应体系

利用正交试验设计研究Taq DNA聚合酶、DNA模板、引物(UBC 886)、dNTP、Mg2+浓度5个因素对云南八角ISSR-PCR反应的影响,建立其最佳反应体系。结果表明:25μL的反应体系中5个因子的最佳水平为:Mg2+3 mmol/L、Taq DNA聚合酶0.5 U、DNA模板0.016 ng、引物0.8μmol/L、dNTPs 0.2 mmol/L。PCR最佳反应程序为:94℃预变性5 min;94℃变性30 s,46℃退火45 s,72℃延伸1 min,40次循环;72℃最后延伸7 min,4℃保存。     

葡萄ISSR-PCR反应体系的建立与优化

采用正交设计L9(34)对影响葡萄ISSR-PCR反应体系的4个因素(dNTP、TaqDNA聚合酶、引物、模板DNA)在3个浓度水平上进行试验,并通过直观分析初步确定其反应体系;在此基础上,通过单因素试验探讨了dNTP、TaqDNA聚合酶、引物、模板DNA、退火温度及循环次数等因素或条件对葡萄ISSR-PCR扩增结果的影响,确定最佳反应水平。最终建立了葡萄ISSR-PCR扩增的最佳反应体系:在25μL的反应体系中,dNTP浓度0.2 mmol/L,TaqDNA聚合酶的用量0.5 U,引物浓度0.4mmol/L,DNA模板用量40 ng。反应程序:94℃预变性5 min;94℃变性1 min,52℃退火1 min,72℃延伸1 min 30 s,40次循环;最后72℃延伸10 min,10℃保存。     

云南松SSR-PCR反应体系的建立与优化

为了建立适宜云南松SSR-PCR的反应体系和扩增程序,利用近缘种火炬松的引物,采用正交设计L16(45)对云南松SSR-PCR反应体系的5因素(Taq酶、Mg2+、模板DNA、dNTP、引物)在4个水平上进行优化,筛选出各反应因素的最佳水平,建立了适于云南松的SSR反应体系.在10μL的反应体系中,模板DNA的用量为30.0 ng,Taq DNA聚合酶的用量为1.0 U,Mg2+的浓度为2.0 mmol/L,dNTPs浓度为0.4 mmol/L,引物的浓度为0.2 μmol/L.扩增程序为:94℃预变性4 min;94℃变性45 s,48℃退火30 s,72℃延伸30 s,30个循环;72℃延长10 min,4℃保存.最后利用1个居群对该体系进行稳定性验证,结果可用于云南松SSR标记的研究.     

均匀设计优化建兰ISSR-PCR体系

采用均匀设计,对影响建兰ISSR-PCR体系的引物、Mg^2＋、dNTP和Taq DNA聚合酶浓度等进行4因素5水平和4因素3水平两轮优化,建立了适合于建兰ISSR-PCR的反应体系：在20μL反应体系中,舍引物0．25μmol／L、Mg^2＋ 2．5mmol／L,dNTP0．2mmol／L、Taq DNA聚合酶1.5U和模板DNA40ng．在此基础上对扩增程序中的循环次数和退火温度,以及ISSR引物进行筛选．筛选获得的扩增程序为：94℃预变性5min;接着进行32个循环：94℃变性35S,52～56℃退火45S,72℃延伸90s;循环结束后,72℃延伸10min．同时筛选得到14个扩增稳定、多态性丰富的ISSR引物．     

西伯利亚蝗基因组DNA提取及RAPD分析条件的优化

以西伯利亚蝗Gomphocerus sibiricus(L.)为研究材料,利用改良的SDS法提取高质量的DNA,分别测试了dNTP浓度、镁离子浓度、TaqDNA聚合酶用量、模板DNA的量等因素对反应结果的影响。通过各因子的组合比较,建立了西伯利亚蝗RAPD优化体系:25μLPCR反应体系,10×buffer2·5μL;dNTP0·24mmol/L;MgCl22·0mmol/L;Taq DNA聚合酶1U;DNA模板45ng;引物30ng。扩增程序为:94℃预变性1min45s、94℃变性30s、35℃退火1min30s、72℃延伸2min,45个循环、72℃延伸10min。结果表明,利用优化的反应条件进行西伯利亚蝗基因组DNA分析,实验有着良好的重复性和稳定性。     

正交设计优化紫萼藓科植物的ISSR-PCR反应体系

目的:建立紫萼藓科(Grimmiaceae)植物ISSR-PCR反应的最佳体系。方法:通过L16(45)正交试验,研究了dNTP浓度、镁离子浓度、模板DNA浓度、引物浓度、Taq DNA聚合酶浓度这5个因素在4个水平上对ISSR-PCR的影响。结果:建立了紫萼藓科ISSR-PCR反应的最佳反应体系,其中dNTPs浓度为0.8mmol/L、Mg2+浓度为3.0mmol/L、模板为15ng、引物浓度为1.4μmol/L、Taq酶量2U,总体积为25μl。反应程序为:扩增程序为:94℃预变性5min;94℃变性30s,48～52℃退火1min,72℃延伸2min,共40个循环;72℃延伸10min;4℃保存。采用引物UBC812等均能够得到有效扩增。结论:该优化体系的建立为下一步对紫萼藓进行ISSR分子标记奠定了基础。     

长心卡帕藻RAPD-PCR反应体系的正交优化研究

采用SDS(十二烷基硫酸钠,20%)法提取了大型海藻长心卡帕藻(Kappaphycus alvarezii)基因组DNA.通过单因子梯度试验,确定了影响随机扩增DNA多态性(RAPD)扩增结果的模板、Mg2 、dNTPs、S22引物、Taq的适宜浓度、退火温度和反应的最佳循环次数;利用正交试验优化了模板、Mg2 、dNTPs、S22引物、Taq的配比浓度.结果表明,在进行长心卡帕藻的RAPD扩增时,在总体积为25μl的反应体系中,模板、Mg2 、dNTPs、S22引物、Taq的最佳浓度分别为15ng、2.0mmol/L、0.2mmol/L、0.25μmol/L、2.5U;退火温度为37℃.反应程序为94℃预变性5min,然后经94℃变性30s、37℃退火1min.72℃延伸2min,进行30次循环,最后在72℃再延伸10min.     

华顶杜鹃ISSR反应体系的优化及亲缘关系的初步分析

以华顶杜鹃为材料,利用单因素试验确立适合华顶杜鹃ISSR-PCR的优化反应体系:在25μL反应体系中,Mg2+1.5或2.0mmol/L,dNTPs 0.3mmol/L,引物0.40μmol/L,Taq DNA聚合酶lU,模板DNA 40ng;分析ISSR-PCR反应体系中Mg2+、dNTP、引物、模板DNA、Taq DNA聚合酶浓度及退火温度对ISSR-PCR反应的影响。PCR扩增程序:预变性94℃ 3min;变性94℃ 45s;退火(Tm+2)℃(根据引物不同设定)75s;延伸72℃ 1.5min;40个循环;继续延伸72℃ 10min;1.5%琼脂糖电泳分离PCR产物。并以优化好的体系初步分析华顶杜鹃及5个近缘种(茶绒杜鹃、Rhododendron mayebrae、Rh.sataense、南平杜鹃和映山红)的亲缘关系,6个种明显地聚为2大类:A类含有映山红、南平杜鹃;B类含有茶绒杜鹃、Rh.sataense、Rh.mayebrae与华顶杜鹃,为明确华顶杜鹃的系统地位提供可借鉴的依据。     

广西甜茶ISSR-PCR反应条件的建立与优化

为了探讨广西甜茶ISSR实验中的多种因素对实验结果的影响,采用单因素法对PCR反应体系中的5个潜在因素(Mg2+, dNTP,引物, Taq酶和模板DNA)在5水平上进行优化实验,并进一步优化了反应程序中的退火温度和循环次数。结果表明：25滋L的最佳反应体系为,1×PCR Buffer、MgCl22.0 mmol/L、dNTP 0.2 mmol/L、引物0.8滋mol/L、Taq DNA聚合酶0.75 U、模板DNA 80 ng;最佳反应程序为：在94℃下进行3 min预变性;随后循环扩增35次(包括94℃变性1 min,54℃退火1 min,72℃延伸1 min);最后在72℃下延伸10 min。本研究建立的广西甜茶的最佳ISSR-PCR反应条件为进一步进行遗传多样性研究奠定了基础。     

正交设计优化绿竹ISSR-PCR体系和引物筛选

旨在建立绿竹ISSR-PCR最佳反应体系和扩增程序,并筛选适于绿竹ISSR-PCR分析的高多态性引物。以绿竹基因组DNA为ISSR-PCR扩增模板,采用正交试验方法,对d NTPs浓度、Mg2+浓度、Taq DNA聚合酶浓度、引物浓度、模板DNA用量设计5因素4水平试验,采用极差分析法和方差分析法对试验结果进行分析。并对退火温度和循环次数进行筛选,建立绿竹ISSR-PCR最佳反应体系和扩增程序。并利用优化后的体系对100条ISSR引物进行筛选。最终确定的最佳反应体系为:20μL的扩增体系中,d NTPs浓度为0.2 mmol/L,Mg~(2+)浓度为2.0 mmol/L,Taq DNA聚合酶浓度为1.5 U,引物浓度为0.4μmol/L,DNA浓度为60 ng,10×PCR Buffer体积为2μL、剩下用灭菌ddH_2O补全。各因素影响大小依次是:Mg~(2+)d NTPs模板DNATaq DNA聚合酶引物。扩增程序为:94℃预变性5 min;94℃变性45 s,(根据引物的退火温度)复性30 s,72℃延伸90 s,循环38次,72℃延伸10 min,4℃保存。以此体系为基础进行引物筛选,在100条ISSR引物中筛选出14条扩增条带清晰、多态性较高、重复性好的引物。     

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.