晒黄烟种质资源遗传多样性分析与评价

为加强晒黄烟资源的收集保存与利用,本研究对来源于国家烟草中期库的6份晒黄烟和新收集的26份晒黄烟进行了SSR分子标记研究,根据来源不同将32份种质分成Z(资源库)、G(广西贺州)以及M(广西百色)3个群体。结果表明,(1)106对SSR引物共检测到110个位点,其中85个为多态性位点,多态性比率为77.27%,种质间的遗传相似系数变异范围为0.49~0.95,表明种质间遗传基础比较狭窄。(2)3个群体内遗传差异由大到小分别为:ZMG。Z与M的遗传相似系数为0.7762,遗传距离相对较远,G与M遗传相似系数为0.8963,遗传距离较近。(3)在相似系数0.49处可将32份种质分成2类,第1类包括寸三皮和大宁旱烟籽,第2类包括3个亚类,其中来源于Z群体的公会晒烟与新收集晒黄烟品种(系)归为一类,Z群体的其他种质与新收集种质遗传距离较远。(4)来自不同地点的同名种质大宁烟遗传距离相对较远,相似系数为0.788。不同名称的公会包盖烟和凤凰黄烟遗传相似性最高,相似系数为0.939。     

贵州桃种质资源遗传多样性的SCoT分析

应用SCoT分子标记技术对71份贵州桃种质进行遗传多样性分析,以期从分子水平上揭示其遗传多样性及资源间的遗传关系,为科学保存与利用贵州桃种质资源提供依据。结果表明:(1)16条引物共检测出192个位点,其中多态性位点数156个,多态性比例为81.25%,平均每条引物扩增位点为12个;供试材料Nei’s遗传多样性指数(H)为0.265 0±0.186 1,Shannon’s信息指数(I)为0.400 3±0.254 3,遗传相似系数变幅为0.400 0~0.852 5。(2)UPGMA聚类分析显示,在相似系数0.65处可将71份桃资源分成6类,其中2份白花桃资源、2份血桃资源、2份青桃资源分别为同名异物。研究认为贵州桃种质具有较丰富的遗传多样性,采用该分子标记技术区分了同名异物的桃资源。     

山药种质资源的ISSR分析及初级核心种质库的构建

采用ISSR分子标记技术对中国不同产地的35份山药种质资源进行遗传多样性分析,并用最小遗传距离逐步抽样法构建核心种质库。结果表明:(1)筛选出12个有效引物共扩增出142个位点,多态性比率为97.18%,平均Shannon’s信息指数(I)为0.4230,平均Nei’s基因多样性指数(h)为0.269 4,平均有效等位基因数(Ne)为1.427 1,平均等位基因数(Na)为1.971 8,说明35份山药种质遗传多样性很丰富。(2)聚类分析表明,种质间的遗传相似系数介于0.54~0.97之间,其中来源地不同的个别种质间的遗传相似系数也很高。(3)经6次逐步抽样,随着抽取种质数目的减少,种质库遗传多样性参数变化不明显,而多态性比率在其中5次逐步抽样中呈现下降趋势;但抽样4在抽样数是抽样前的31%时,多态位点率仍可达到抽样前的97.8%,说明抽样4所构建的山药核心种质库最具代表性。     

基于ISSR标记的烤烟种质遗传多样性研究

利用ISSR标记分析了24份代表性烤烟种质的遗传多样性。从100个ISSR引物中筛选出10个引物,通过聚丙烯酰胺凝胶电泳可以检测到208条稳定的条带,片段大小介于200~2 400 bp之间,条带数在7~37条之间;扩增片段中多态性带141条,平均多态性比率(PPB)为67.79%。 通过UPGMA聚类分析,24个烤烟品种分为5类,最大一类有12个材料,主要衍生于Coker319。品种间遗传相似指数(GS)范围为0.66~0.85,表明其遗传多样性较低,需要拓宽烤烟种质的遗传基础。同时,利用2个多态性好的ISSR引物可以将这24份烤烟材料区分开,每个品种都有各自独特的指纹图谱,表明ISSR标记适于烟草品种鉴定和遗传多样性研究。     

基于RSAP标记的大花三色堇遗传多样性分析

采用限制性位点扩增多态性(RSAP)标记技术,对来源于国内外不同地区的41份大花三色堇种质资源遗传多样性进行分析,并用Bayesian法和UPGMA法分别对其进行遗传结构和亲缘关系分析。结果表明:筛选的26对RSAP引物组合共扩增出588条带,其中多态性条带567个,多态性比率为97.03%,平均每对引物扩增出22.62个位点和21.81个多态性位点,18对引物组合的鉴别能力达到100%,说明RSAP在大花三色堇遗传多样性分析中有较好的适用性和较高的分析效力。41份大花三色堇种质Nei’s遗传多样性指数和Shannon信息指数均值分别为0.248 9、0.395 1,高于自花授粉植物烟草,与异花授粉植物玫瑰相近,表明大花三色堇遗传多样性较为丰富。遗传结构分析将41份大花三色堇种质分为6个组群,组群的划分与种质的地理来源存在较高相关性。基于Nei’s遗传相似系数,41份大花三色堇种质分为3大类,其中第3大类又可细分为4个亚类,来源于相同或相近地域的种质大多聚在一起,表明大花三色堇的种质交流存在地域限制。按地理来源划分的种质群亲缘关系分析显示,中国种质群与荷兰种质群相距最近,与德国种质群最远,提示应加强对德国种质的引进;按花色划分的6个群体Shannon信息指数为0.199 4~0.364 9,其中白色种质群最高,黑色种质群最低,说明白色花遗传多样性基础较广,而黑色花遗传多样性较低。     

甜瓜种质资源遗传多样性的SRAP分析

为研究甜瓜材料之间的亲缘关系及其分类, 更有效地利用种质资源, 为培育新品种提供依据, 文章采用 SRAP (Sequence-related amplified polymorphism)技术对61份甜瓜种质资源的遗传多样性进行研究。结果表明: 从42对引物组合中筛选出16对扩增条带清晰、多态性高的引物组合分析供试材料, 共检测出452个位点, 其中265个为多态性位点, 多态性比率达58.63％, 平均每对引物组合产生28.56个位点和16.56个多态性位点。61份材料间的相似系数为0.48～0.93, 平均为0.73。这些结果说明, 供试甜瓜材料具有较为丰富的遗传多样性。聚类分析结果表明, 61个甜瓜品种中首先可分为薄皮甜瓜与厚皮甜瓜两大类, 彼此亲缘关系最远。以遗传相似系数0.74为截值, 可把供试材料分为5个类群。在生态区域中, 新疆厚皮甜瓜的Nei’s基因多样性指数(0.2231)和Shannon’s信息指数(0.3422)最高。     

利用SRAP标记分析贵州砂梨资源遗传多样性

采用SRAP标记技术,对贵州59份砂梨种质的遗传多样性进行分析。结果表明:(1)筛选的15对SRAP引物共扩增出151个位点,其中120个是多态性位点,多态百分率为79.47%。(2)POPGENE分析表明,贵州砂梨资源在物种水平上有效等位基因数(Ne)为1.355 9,Nei’s基因多样性指数(H)为0.216 9,Shannon’s信息指数(I)为0.336 2;在区域品种群水平Ne=1.261 1,H=0.155 5,I=0.235 2,以黔西南地区资源的遗传多样性最高,六盘水市最低。(3)聚类分析显示,在遗传相似系数0.75处,可将59份砂梨资源分为6个组,聚类分析结果具有一定的地理区域特性。研究认为,贵州砂梨种质具有较为丰富的遗传多样性,并表现出明显的地理区域特性;SRAP标记与ISSR标记在揭示贵州砂梨种质遗传多样性上具有高度的一致性,但SRAP标记能在更小的变异范围内揭示更多的遗传信息。     

皂荚种质资源SCoT遗传多样性分析及指纹图谱的构建

采用SCoT标记分析了18个皂荚种质的遗传多样性,并采用UPGMA法对18个皂荚种质进行了聚类分析。在此基础上,通过筛选出的多态性条带构建了18个皂荚种质的SCoT指纹图谱。扩增结果表明:从51个SCoT引物中筛选了15个引物进行PCR扩增,共扩增出226条带,其中多态性条带216条,多态性比率为96.61%。各引物多态性信息含量(PIC)、观测等位基因数(Na)、有效等位基因数(Ne)、Nei’s基因多样性指数(H)和Shannon’s信息指数(I)的平均值分别为0.875 9、1.964 9、1.440 1、0.272 6、0.426 1。18个皂荚种质的遗传相似系数在0.491 4~0.938 1之间,表明供试材料之间具有较丰富的遗传多样性。聚类分析结果表明:在遗传相似系数为0.60处可将18个皂荚种质分为3组,其中野皂荚单独为一组,山皂荚和皂荚-T聚为一组,其它皂荚材料聚为一组。利用3个引物扩增的8个多态性位点构建了18份皂荚种质资源的DNA指纹图谱,可以将其区分并精准鉴定。该研究结果为皂荚种质的鉴定和新品种选育提供了一定的理论依据。     

山茱萸种质资源的ISSR遗传多样性分析与初级核心种质库的构建

采用ISSR 标记技术对不同来源地的48份山茱萸种质资源的遗传多样性进行了分析,并依据最小遗传距离逐步抽样法构建了该初级核心种质资源库.结果显示:筛选出的13个多态性引物共扩增出190个位点,多态性位点比率达93.16%,平均Shannon信息指数(I)为0.402 5,平均Nei's基因多样性指数(H)为0.259 4,平均有效等位基因数(NE)为1.425 0.聚类分析表明,种质间的遗传相似系数介于0.65～0.90之间,除个别种质外,48个种质聚类结果与地区来源有较高的一致性.随着抽取种质数目的减少,多态性比率明显降低,但种质库遗传多样性参数变化较小;抽样3构建的初级核心种质库最具代表性,抽样数是抽样前的30%左右,多态位点比率是抽样前的96.0%.     

胡麻种质资源遗传多样性及亲缘关系的SRAP分析

利用SRAP分子标记,对国内外5个不同地区161份胡麻种质资源的遗传多样性及亲缘关系进行研究,为胡麻育种提供科学依据。结果表明:(1)20对引物扩增出307个条带,其中有192个多态性条带,多态比率为62.54%,平均每对引物组合有9.60个多态性位点,每对引物的多态性信息量(PIC)为0.51~0.76,平均为0.61。(2)有效等位基因数(Ne)、香浓信息指数(I)和Neis遗传相似系数(H)在物种水平上分别为1.582 0、0.521 1和0.346 5,在群体水平上分别为1.491 1、0.431 1和0.286 3。(3)各群体遗传多样性指数表现为中国西北群体中国华北群体美洲群体亚洲群体欧洲群体。(4)聚类分析结果显示,在遗传相似系数为0.335 5处,将161份胡麻资源分为2大类;在0.455 0处,分为5个亚类,与国内外5个不同地区来源吻合。研究表明,中国西北地区胡麻品种(系)的遗传多样性最为丰富;地域是影响胡麻种质资源遗传多样性的主要因素;国内、外品种(系)间的遗传差异较大,表现出较远的亲缘关系。     

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.