乌塌菜种质资源遗传多样性的ISSR分析

利用ISSR技术对48份乌塌菜种质资源进行遗传多样性分析。从60条随机引物中筛选出稳定性强、条带清晰且多态性丰富的9条引物进行PCR扩增,共扩增出103条谱带,平均每个引物扩增出11.4条带,其中多态性带85条,多态性位点百分率为82.68%。不同乌塌菜种质间遗传相似系数变幅为0.59~0.97,说明ISSR标记能够揭示材料间较高的遗传多样性。利用UPGMA聚类分析,ISSR标记能将48份乌塌菜品种完全区分开,48份乌塌菜种质被划分为4个类群,聚类结果与叶片颜色相关,为乌塌菜品种资源的研究利用提供参考。     

观赏南瓜及葫芦种质资源遗传多样性分子评价

利用RAPD和ISSR标记对28份观赏南瓜及葫芦种质资源进行遗传多样性分子评价。结果表明:12个RAPD引物和13个ISSR引物分别扩增出89条和93条清晰谱带,平均每个引物分别扩增出6.1条和6.2条多态性谱带,多态性比率分别为82%和86%。RAPD和ISSR标记检测供试材料的遗传相似性系数(GS)范围分别为0.31～0.99和0.33～0.99,ISSR(平均GS值0.68)检测多态性效果高于RAPD(平均GS值0.73)。利用UPGMA法基于RAPD与ISSR混合聚类,将28份观赏南瓜及葫芦种质分为3类,类群的划分与果实形状明显相关:第Ⅰ类群包括15份种质,为扁圆形、卵圆形、圆球形或圆筒状的早熟或晚熟果实;第Ⅱ类群包括11份种质,为汤匙形、梨形、扁球形或皇冠形的早中熟果实;第Ⅲ类群包括2份种质,为葫芦形的晚熟果实。     

叶子花种质资源遗传多样性及亲缘关系的RAPD和ISSR分析

利用RAPD和ISSR标记对48份叶子花种质进行遗传多样性及亲缘关系分析。结果显示:(1)筛选出具有多态性的RAPD引物7条、ISSR引物11条,RAPD引物共扩增97条多态性条带,ISSR引物共扩增140条多态性带,多态性百分率均达100%。(2)根据两种标记的扩增结果,用UPGMA法对48份叶子花种质的聚类分析显示,48份供试材料间具有较丰富的遗传多样性,其品种间遗传相似系数RAPD为0.318 8～0.955 6,ISSR为0.349 5～0.900 0;两种分子标记均能清楚地将48份种质材料区分开来,对种质类群的划分结果基本一致,仅有些许差异。(3)聚类分析结果显示,48份种质可分为两大种系:1)B.glabra种系,其品种大多以其种内来源为主;2)涵盖了B.spectabilis、B.peruviana、B.×buttiana和B.×spectoglabra等4个种的种系,种质构成较为复杂。(4)两种标记聚类结果呈显著相关关系,相关系数为0.752 3。研究表明,对一些形态上无法细分的叶子花种质(类群),RAPD和ISSR分子标记是可靠的鉴别方法。     

绿豆种质资源的ISSR遗传多样性分析

利用ISSR标记对33份绿豆种质进行了遗传差异和亲缘关系分析。 结果表明,从46条ISSR引物中筛选出10条扩增条带清晰、多态性高的引物,利用这10条引物从33份绿豆种质中共扩增出118条条带,其中多态性条带115条,多态性位点比例98.18%。遗传相似性与聚类分析结果表明,供试绿豆种质间的遗传相似系数范围为0.50～0.98之间,平均0.68。当遗传相似性系数为0.682时,供试33份绿豆种质资源分为4个ISSR类群( ISSR Groups,IGs),第Ⅰ类群包括产地为黑龙江、吉林共9份和河北的1份绿豆种质资源,第二类群包括河南、山西和陕西的所有和河北的4份绿豆种质资源,第三类群为来自泰国的5份绿豆抗虫资源,第四类群包括山东和内蒙各2份绿豆资源;当遗传相似系数为0.98时,供试的33份绿豆种质资源可被全部区分开。 ISSR分析结果表明, ISSR类群划分与绿豆的地理来源存在一定相关性;而同一类群中,地理来源相同的绿豆种质间也存在一定的遗传差异。     

苏州东山茶树种质资源遗传多样性的ISSR分析

利用ISSR分子标记对苏州洞庭地区的51份茶树(Camellia sinensis)种质资源进行遗传关系研究。结果表明,从12条引物中筛选出6条引物,共扩增出76个位点,其中多态性位点70个,占92.11%。51份茶树种质资源遗传相似性(GS)变化范围0.37～0.89;其中白沙和东灵1号GS值最大、遗传相似程度最高、遗传距离最近。通过类平均聚类(UPGMA)法,可将51份材料分为2个大类,每一大类又分为4个亚组,相同亚组下的亲缘关系较近。其中,部分来自同一品种的不同品系具有较高的遗传相似性系数。ISSR标记可有效评价苏州茶树种质的遗传多样性,为更有效地保护和利用茶树种质资源和茶树优良品种的选育提供遗传信息。     

用ISSR标记分析红麻种质资源的遗传多样性

为明确红麻种质资源的遗传多样性和亲缘关系,以20个国家的32份红麻(Hibiscus cannabinus L.)种质资源为材料,从90个ISSR引物中筛选出22个多态性引物对供试材料进行PCR扩增,最终选用条带最清晰、多态性明显的13个引物的扩增数据进行统计分析.结果表明:(1)13条ISSR多态性引物共扩增出谱带总数59条,多态性条带总数为47条,多态性条带比率达79.66%,其遗传多样性较丰富;(2)在切割线L1取值为0.73时,可将供试材料分为一个由22份栽培品种构成的L1-1大类群,以及由8份野生材料和2份古老地方品种构成的3个独立的个类和3个不同小类群.(3)当切割线L2取值为0.77时,又可将第1个大类群L1-1中22份栽培品种根据其亲缘关系,重新划分为I1、I2、I3、I4 4个不同的亚类群,各亚类群表现出明显的地域性特点.(4)聚类结果显示,红麻多数栽培品种之间的遗传差异较小,亲缘关系较近,其遗传多样性比野生材料明显狭窄.     

茄子耐盐种质资源遗传多样性的SRAP和ISSR分析

利用SRAP和ISSR分子标记,研究了14份耐盐茄子种质资源的遗传多样性,结果表明,2种标记均能揭示材料间较高的遗传多样性,其中ISSR标记多态性略高于SRAP标记。在SRAP分析中,每对引物组合可扩增出8-15条DNA片段,平均为12．12条：26对SRAP引物组合共扩增出315条DNA片段,其中263条具有多态性,多态性比率为83．49％;材料间遗传相似系数变化范围为0．212～0．923,平均值为0．755。在ISSR分析中,每个引物可获得5～16条DNA片段,平均为10．87条;15个ISSR引物共扩增出163条DNA片段,其中141条具有多态性,多态性比率为86．50％;材料间遗传相似系数变幅为0．333-0．957,平均值为0．736。聚类分析表明,2种标记都能将供试材料完全区分开来,聚类结果具有一定的相似性,但也存在明显差异。Mantel相关分析表明,SRAP分析与ISSR分析的相关性达到极显著性水平（r=0．904,P〈0．01）。     

不同生态类型龙眼种质亲缘关系的ISSR分析

利用ISSR分子标记技术对不同生态类型的39份龙眼种质进行亲缘关系分析。研究结果表明,从100条ISSR引物中筛选出12条重复性好、条带清晰的引物,对39份龙眼种质基因组DNA进行扩增,得到152个位点,其中多态性位点117个,多态性比例为76.97%。供试龙眼种质间遗传相似系数变幅为0.57～0.92,说明ISSR标记能够揭示材料间较高的遗传多样性。UPGMA聚类结果表明,在0.65相似水平可以将39份龙眼种质分为3个类群,类群Ⅰ均为来自中国的南亚热带生态型龙眼;类群Ⅱ包括石硖和大乌圆2个南亚热带生态型龙眼品种,以及热带生态型龙眼四季蜜类型的品种和单株;类群Ⅲ包括来自越南和泰国的龙眼种质。不同生态类型对龙眼的亲缘关系影响不大,热带生态型和南亚热带生态型龙眼相互聚在一起,说明两种不同生态类型龙眼具有较多相同的遗传背景。本试验结果将有助于进一步开展龙眼的分类、遗传与进化研究。     

紫、红黄肉甘薯种质遗传多样性的ISSR分析

采用ISSR分子标记,分析了21份紫肉、28份红黄肉甘薯种质遗传多样性。结果表明：17对引物共扩增出154条谱带,其中多态性谱带138条,占89.6%,平均每个引物扩增出8.12条多态性谱带,表现出丰富的多态性。聚类分析和主成分分析将49份甘薯种质聚为4大类,类型间遗传差异较大,将红黄薯单独聚为1类,说明紫薯和红黄薯分别具有明显不同的来源和系统演化关系。种质间的遗传相似系数变幅为0.58~0.93,其中,0.61~0.70之间的种质占51.4%,0.71~0.80之间的占44.0%。而邻近地域育种单位或同一育种单位的品种亲缘关系较近。文章对如何在育种中利用这些优异种质进行了讨论。     

福建省野牡丹属种质资源的ISSR分析

为探讨福建省野牡丹属(Melastoma L.)植物的亲缘关系,运用ISSR分子标记技术对源自福建省的野牡丹属野生种质及部分实生后代共34份材料进行分析。结果表明,11条多态性引物对34份种质DNA进行扩增,共获得112条完整、清晰的谱带,其中多态性条带104条,多态性比率为92.9%,表明野牡丹属种质资源具有较高的遗传多样性。34份种质材料的相似系数为0.55~0.93,平均相似系数为0.71,表明这些材料间的亲缘关系较近。聚类分析表明34份材料可划分为3个类群5个亚类,主坐标散点分析可分为4个类群,这与亲缘关系分析的结果基本一致。这从分子水平上揭示了福建省野牡丹属野生种质及部分具备优良园艺性状实生后代的亲缘关系,为该属植物的良种选育工作提供了理论依据。     

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.