番茄LeNHX1基因植物过量表达载体的构建及表达分析

从番茄幼苗中提取RNA,根据NCBI中番茄LeNHX1基因序列设计引物,通过RT-PCR获得了番茄LeNHX1基因的cDNA序列,包含一个1 605 bp的开放阅读框,编码534个氨基酸。将cDNA序列连接到植物过量表达载体PBI121上,对所获得的重组质粒进行双酶切鉴定,结果表明,植物过量表达载体PBI121-LeNHX1已构建成功。半定量RT-PCR结果表明LeNHX1基因在根、茎和叶中均表达,盐、低温和脱落酸的诱导能提高LeNHX1基因的表达量,推测番茄LeNHX1基因在逆境应答中可能起着重要作用。     

茶树CsPNPO基因的功能鉴定与表达分析

PNP氧化酶是VB_6代谢途径中一个重要的转化酶。该研究以茶树‘龙井43’为材料,采用RT-PCR方法克隆PNP氧化酶基因,以pET22b(+)为载体构建原核表达载体,通过IPTG进行诱导表达并进行功能鉴定;采用荧光定量PCR方法分析茶树不同组织中CsPNPO基因的表达差异以及在低温和干旱胁迫下的表达特征,为进一步解析茶树VB_6的生理生化功能奠定基础。结果表明:(1)茶树CsPNPO编码框长度为1 503 bp,编码501个氨基酸,分子量为48.5 kD,理论等电点5.82,不含信号肽,属于亲水性的非分泌蛋白,定位于叶绿体;氨基酸序列分析结果显示,其有叶绿体转运肽区域、YjeF-N功能域和PNP氧化酶功能域。(2)成功构建pET22b(+)-CsPNPO原核表达载体,并在pH 8.5、37℃时测定重组蛋白有较强的PNP氧化酶活性。(3)荧光定量PCR检测结果显示,CsPNPO基因在茶树叶中的表达量最高,其次是茎,根的表达量最低仅为叶的十分之一,表明CsPNPO基因具有组织表达特异性;在低温和干旱条件下CsPNPO基因的表达量下降明显,推测CsPNPO基因可能参与了茶树对低温和干旱的逆境应答。     

葡萄抗白粉病相关基因γVPE的克隆与表达分析

该研究采用RT-PCR技术,从抗病的中国野生华东葡萄‘白河-35-1’和感病的欧洲葡萄‘佳丽酿’中克隆了液泡加工酶基因(γVPE),分别命名为VpγVPE和VvCγVPE。克隆的2个γVPE基因cDNA长度均为1 624bp,ORF为1 482bp,编码493个氨基酸。氨基酸多序列对比分析发现,‘白河-35-1’、‘佳丽酿’、‘无核白’和‘黑比诺’葡萄中的γVPE基因底物结合口袋域的3个关键氨基酸之一的丝氨酸(Ser395)均变为丙氨酸(Ala),与其他植物的VPE基因底物口袋结合域有所不同。实时荧光定量PCR表明,在白粉菌诱导后的不同时期内,γVPE基因在感病葡萄和抗病葡萄中的表达模式不同,抗病株系中VpγVPE基因的表达量在诱导后的前期(4h和48h)和后期(168h)均有所增加,而感病株系中VvCγVPE基因在诱导后4h表达量最高,随后降低。γVPE基因在白粉菌诱导后不同时期内表达量的变化,表明γVPE基因在一定程度上与葡萄的抗性相关。研究结果为进一步揭示γVPE基因在抗病过程中的分子机理奠定了基础。     

烟草赖氨酸脱羧酶基因NtLDC1的克隆和表达分析

赖氨酸脱羧酶(lysine decarboxylase,LDC)是生物碱合成第一步所需的关键酶。为研究LDC基因在烟草中特性和功能,本研究采用同源克隆和RT-PCR方法从栽培烟草‘K326’中克隆得到一个LDC基因,命名为Nt LDC1,Gen Bank登录号为KU507075。序列分析表明烟草Nt LDC1基因ORF全长666 bp,编码221个氨基酸的蛋白,相对分子质量为24 264.9 Da,等电点为5.43。不同植物中LDC蛋白较为保守,Nt LDC1与番茄和马铃薯的LDC蛋白高度相似,进化分析表明Nt LDC1与番茄中LDC的亲缘关系最近。利用实时荧光定量PCR对Nt LDC1基因进行组织表达分析,结果显示Nt LDC1基因在烟草根、茎、叶、花中均有表达,在叶片中的表达水平最高。低温可以诱导Nt LDC1基因的表达,在低温处理8 h基因的表达量达到最高,表明Nt LDC1可能在烟草低温胁迫应答中发挥作用。     

芜菁UF3GT基因的克隆及表达特性

目的:克隆‘津田’芜菁和‘赤丸’芜菁的UDP-葡萄糖∶类黄酮3-O-葡萄糖基转移酶(UF3GT)基因并研究其表达特性。方法:利用RT-PCR方法克隆‘津田’芜菁BrUF3GT1基因和‘赤丸’芜菁BrUF3GT2基因,并进行生物信息学分析;通过Northern杂交检测BrUF3GT1和BrUF3GT2基因的UV-A诱导表达特性;对BrUF3GT1和BrUF3GT2基因进行原核诱导表达。结果:BrUF3GT1和BrUF3GT2的开放读框为1407 bp,编码468个氨基酸残基;氨基酸序列分析显示,BrUF3GT1和BrUF3GT2与拟南芥UF3GT的同源性为87%,从第16~453位氨基酸残基的肽段具有糖基转移酶家族成员的结构域;BrUF3GT1和BrUF3GT2基因具有高度同源性,核苷酸序列在7个位点存在差异,推导的氨基酸序列在1个位点存在差异;Northern杂交结果显示,UV-A可以诱导BrUF3GT1和BrUF3GT2基因表达,基因的表达量与处理时间相关;原核诱导表达及纯化后可以获得相对分子质量分别约为51.88×103和51.89×103的BrUF3GT1和BrUF3GT2蛋白。结论:克隆了‘津田’芜菁和‘赤丸’芜菁的UF3GT基因,为初步阐明2种芜菁的花青素生物合成机理奠定了实验基础。     

茶树谷丙转氨酶基因的克隆及其表达分析

该研究基于茶树的转录组数据,采用RT PCR方法从茶树‘黄金芽’cDNA中克隆获得茶树谷丙转氨酶基因（CsAlaAT）,利用荧光定量PCR方法,对CsAlaAT在茶树材料‘迎霜’和‘黄金芽’不同组织、温度胁迫与激素处理的表达进行分析。结果显示：CsAlaAT基因开放阅读框长度为1 662 bp,编码553个氨基酸,含有天冬氨酸转氨酶家族（Aspartate aminotransferase family）典型的AAT like保守结构域。多序列比对显示,该序列与多个相关物种的序列一致性达78.83%,与磷酸吡哆醛（PLP）结合的10个氨基酸残基以及第358位赖氨酸催化位点在物种间高度保守。茶树CsAlaAT蛋白属亲水性蛋白,相对分子质量为60 877.5 D,等电点为6.11,碱性、酸性、脂肪族和芳香族氨基酸比例分别为12%、11%、22%和8%,无序化特征不明显,与大麦HvAlaAT具有相似的三维结构。实时定量PCR分析表明,CsAlaAT在茶树‘迎霜’和‘黄金芽’中的表达均具有组织特异性,且均在根部的表达量最高;CsAlaAT响应高温（38 ℃）和低温（4 ℃）胁迫的表达上调;外源施用脱落酸（ABA）和赤霉素（GA）能够抑制茶树中CsAlaAT基因的表达。     

茶树CsCIGR基因克隆及表达特性分析

该研究以茶树基因组数据库为基础,采用RT-PCR技术,从茶树‘龙井43’中克隆得到基因CsCIGR。序列分析显示,CsCIGR基因开放阅读框长度为1 677 bp,编码588个氨基酸。进化分析表明,CsCIGR属于GRAS家族的PAT1亚家族。多序列比对显示,茶树CsCIGR蛋白与其他植物的GRAS蛋白氨基酸序列具有很高的相似性。氨基酸理化性质分析显示,CsCIGR转录因子属于亲水性蛋白。亚细胞定位预测显示,CsCIGR可能位于细胞核中。启动子预测分析发现,CsCIGR启动子区域包含胁迫响应元件(STRE)、干旱应答元件(MYC)、厌氧诱导元件(ARE)等多种与逆境响应相关的顺式作用元件。荧光定量PCR分析结果显示,CsCIGR基因在低温(4℃)、高温(38℃)、干旱(200 g·L~(-1) PEG)、高盐(200 mmol·L~(-1) NaCl)胁迫下均能诱导表达,且对高盐,低温和高温胁迫响应更为明显,推测CsCIGR基因在茶树响应逆境胁迫中发挥重要作用。该研究为茶树抗性育种筛选基因提供了重要理论依据。     

茶树硝酸盐转运蛋白基因的克隆和表达分析

硝酸盐转运蛋白（NRT）是植物吸收和利用硝态氮的一种关键蛋白。运用RACE技术从茶树中扩增出NRT基因的cDNA,并利用实时荧光定量PCR检测了CsNRT基因在不同茶树器官与品种之间的差异表达。结果表明：CsNRT基因的cDNA全长2 061 bp,开放阅读框为1 818 bp,编码含由605个氨基酸组成的蛋白质,GenBank登录号为KJ160503,属于NRT2基因家族。CsNRT为组成型基因,对不同处理的水培茶苗进行定量表达分析显示,该基因在根、茎、叶中都有表达,其中在根部的表达水平最高,1.0 mmol·L-1的NO3-可诱导其表达量上升7.53倍。不同茶树品种中CsNRT基因的表达也有较大差异,‘龙井长叶’和‘凫早2号’的表达量较高,前者强烈响应0.5和1.0 mmol·L-1 NO3-的诱导,后者的响应浓度为1.0和2.0mmol·L-1,而‘舒茶早’在各浓度下的表达差异不明显。     

猪干扰素-α基因的克隆及其植物表达载体的构建

目的:克隆与分析猪干扰素-α(INF-α)基因,构建猪干扰素基因的高效植物表达载体。方法:根据NCBI中DQ248997序列设计引物,以猪的总DNA为模板,PCR扩增出猪的INF-α基因,克隆至pBS-T载体后进行序列分析,构建猪干扰素基因的植物表达载体。结果:实验所克隆序列经Blastn比对,98%的核酸序列相同,98%的蛋白质序列相同,3个非功能性氨基酸与基因库中序列不一致,推测为猪INF-α的一个亚型。构建的2个植物表达载体经BamHⅠ/SacⅠ限制性内切酶消化,均可得到570bp的目的基因。结论:成功克隆了猪的INF-α基因,并构建出含猪INF-α基因的高效植物表达载体pBI121/INF和pCAMBIA1301/INF。     

马铃薯糖转运蛋白基因的克隆及表达分析

植物SWEET基因家族是一类糖转运蛋白,在植物的生理活动和生长发育过程中发挥着重要功能。为了解马铃薯SWEET基因的相关信息,探究其在马铃薯不同组织以及在生物胁迫与非生物胁迫下的表达特性。该研究采用同源克隆技术从马铃薯‘青薯9号’中克隆了StSWEET5基因(GenBank登录号为MN295671),其CDS序列长度为717 bp,编码238个氨基酸。系统进化树分析结果表明,StSWEET5与番茄的氨基酸序列相似性最高(97.06%)。qRT-PCR分析表明:StSWEET5基因在马铃薯各组织(根、茎、叶、花、块茎、匍匐茎)中均有表达,且在花中的表达显著高于其他组织;糖胁迫下,StSWEET5基因在根、茎、叶中均有表达,尤其在根中的表达差异最为显著(P0.05)。在晚疫病菌(Phytophthora infestans)诱导后36 h时,表达量达到最高,随后急剧下调。推测StSWEET5基因参与了马铃薯糖胁迫以及响应了晚疫病诱导的过程。     

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.