木霉肽类代谢产物对豇豆土著根瘤菌遗传性状的影响

利用RAPD与ISSR分子标记检测手段,分析了哈茨木霉T2-16肽类代谢产物处理豇豆土著根瘤菌,对其遗传性状的影响,同时,比较了RAPD和ISSR两种不同分子标记在检测根瘤菌种间的遗传相似性以及遗传变异性的分辨力.实验中,从100条引物中筛选到具有多态性的ISSR引物5条,从80条引物中筛选到具有多态性的RAPD引物6条,用5条ISSR引物扩增出54条带,多态性条带比率为75.93 %;6条RAPD引物扩增出61条带,多态性条带比率为68.85 %.两种分子标记均能揭示出处理前后根瘤菌间的遗传差异,但ISSR标记比RAPD标记可检测到更大的遗传变异.根据两种标记的结果,对供试的根瘤菌进行聚类分析,结果表明,土著根瘤菌经木霉肽类代谢产物处理后,与出发菌株相比,表现出一定程度的遗传分化和遗传差异性.     

海带种质资源遗传多样性的RAPD分析

利用RAPD分子标记技术对种质库中保存的19个海带品种(系)的36个海带配子体进行了遗传多样性分析。从100条引物中筛选出16条可扩增出清晰条带的引物,在36个海带配子体中共扩增出362条DNA条带,其中多态性条带比例达99.45%。遗传相似性分析表明,这36个配子体之间的遗传相似性范围为0.682-0.978,以0.756为最低遗传相似系数,可将36个种质材料分为6个大类,UPGMA聚类分析结果表明同一品系的雌雄配子体大部分能聚在一起,品系间遗传多样性较高。     

云南黑籽南瓜种质遗传多样性的RAPD和ISSR分析

摘要: 采用RAPD和ISSR分子标记技术对来源于云南省6个地州13份的黑籽南瓜种质进行遗传多样性分析。结果表明：6个RAPD和6个ISSR引物分别扩增出43条和41条带,多态性比率分别为90.70%和51.21%;RAPD和ISSR标记检测供试材的遗传相似性系数(Gs)范围,分别为0.340-0.895和0.162-0.941,ISSR(平均GS值0.698)检测多态性效果高于RAPD(平均GS值0.481)。RAPD标记聚类分析将供试种质分为3个类群5组;ISSR标记聚类分析将供试种质分为4个类群6组,RAPD和ISSR标记的遗传相似性系数呈显著相关(r=0.536)。基于UPGMA聚类结果,可为黑籽南瓜的引种栽培或品种改良提供参考。     

金银花五个品系的RAPD分析及DNA指纹图谱的建立

运用RAPD技术,对5个金银花品系进行遗传多样性研究并构建这5个金银花品系的DNA指纹图谱。从80个引物中筛选出25个带纹清晰,多态性好的引物用于实验。其中,引物SBSD06的扩增条带可以清楚明确区分5个品系,建立其DNA指纹图谱。在清晰、稳定出现的170条带中,153条带具有多态性。按UPGMA法进行聚类分析,计算其遗传相似系数,结果显示,金银花5个品系聚为两类,与其形态学分类结果相符。     

苎麻疫霉群体的RAPD分析

利用从126个RAPD(Random Amplifled Polymorphic DNAs)随机引物中筛选到的可扩增出清晰条带、主带明显、稳定的8条引物,对采集自江苏、安徽和江西不同寄主的45个Phytophthora boehmeriae菌株进行全基因组DNA RAPD标记遗传多样性分析。选用引物共标出DNA指纹图带68条,其中多态性条带20条,多态性检测率为29．4％,表明该种内不同地区和寄主来源的菌株间变异较小。利用Popgene软件计算供试菌株间的遗传距离并绘制聚类树状图,供试菌株被划分为2个遗传聚类组。菌株间的遗传相似性与菌株的寄主来源有一定的相关性,来自江苏、江西和安徽棉花上的27个菌株被划分在同一遗传聚类组内,而分离自构树、枫杨和苎麻的18个菌株被划分在另一个遗传聚类组。结果还表明菌株间遗传相似性与其地区来源无直接相关性。     

苎麻疫霉群体的RAPD分析*

利用从126个RAPD(RandomAmplifiedPolymorphicDNAs)随机引物中筛选到的可扩增出清晰条带、主带明显、稳定的8条引物,对采集自江苏、安徽和江西不同寄主的45个Phytophthoraboehmeriae菌株进行全基因组DNARAPD标记遗传多样性分析。选用引物共标出DNA指纹图带68条,其中多态性条带20条,多态性检测率为29.4%,表明该种内不同地区和寄主来源的菌株间变异较小。利用Popgene软件计算供试菌株间的遗传距离并绘制聚类树状图,供试菌株被划分为2个遗传聚类组。菌株间的遗传相似性与菌株的寄主来源有一定的相关性,来自江苏、江西和安徽棉花上的27个菌株被划分在同一遗传聚类组内,而分离自构树、枫杨和苎麻的18个菌株被划分在另一个遗传聚类组。结果还表明菌株间遗传相似性与其地区来源无直接相关性。     

感病与抗病圭亚那柱花草遗传多样性的AFLP分析

圭亚那柱花草(Stylosanthes guianensts Swartz)原产中南美洲及非洲,是一种重要的热带豆科牧草,已在我国华南热带、南亚热带地区种植并利用.由胶孢炭疽菌(Colletotrichum gloeosporioides(Penz.)Sacc.)引起的炭疽病是柱花草的主要病害.采用扩增片段长度多态性(AFLP)技术分析了42个圭亚那柱花草品系的遗传多样性,同时对其抗病性进行了接种鉴定.从96个选择性引物对中筛选出较好的4个,分别对42个圭亚耶柱花草品系进行扩增,共获得出225条带,其中多态性带215条,平均多态性水平为95.5%,表现出高度的多态性.采用NTSYS-pc软件计算了品系间的遗传相似系数,其变化范围为0.31～0.95.根据非加权成对平均数法(uPGMA)进行聚类分析,建立了42个品系的聚类树系图,以所有品系的平均遗传相似系数0.48为阈值,共分为5类.主成分分析表明:第一主成分和第二主成分对全部品系间遗传变异的贡献率分别为56.04%和6.40%,并建立了品系间相互关系的二维图,各品系在二维图中的分布与UPGMA分类相吻合.抗病性鉴定结果表明:各品系对两种典型的病原菌的抗性有差异,其中抗病品系对两种病原菌的抗病相关系数达到0.904,表明抗病品系对两种病原菌有共同抗性.此外,抗病品系在UPGMA聚类中呈随机分布.这些结果表明,AFLP技术是分析圭亚那柱花草遗传多样性的有效方法.     

苎麻疫霉群体的RAPD分析

利用从126个RAPD(RandomAmplifiedPolymorphicDNAs)随机引物中筛选到的可扩增出清晰条带、主带明显、稳定的8条引物,对采集自江苏、安徽和江西不同寄主的45个Phytophthoraboehmeriae菌株进行全基因组DNARAPD标记遗传多样性分析。选用引物共标出DNA指纹图带68条,其中多态性条带20条,多态性检测率为29.4%,表明该种内不同地区和寄主来源的菌株间变异较小。利用Popgene软件计算供试菌株间的遗传距离并绘制聚类树状图,供试菌株被划分为2个遗传聚类组。菌株间的遗传相似性与菌株的寄主来源有一定的相关性,来自江苏、江西和安徽棉花上的27个菌株被划分在同一遗传聚类组内,而分离自构树、枫杨和苎麻的18个菌株被划分在另一个遗传聚类组。结果还表明菌株间遗传相似性与其地区来源无直接相关性。     

微卫星(TATG)n基序在香菇菌种中的验证

以（TATG）4重复序列为引物对香菇属的3个种13个菌株的微卫星区DNA进行PCR扩增,15%的琼脂糖凝胶电泳,获得了25个条带,并且在供试菌株上表现出多态性,可以实现遗传分类研究。为了验证微卫星分子标记实验准确性,又用RAPD技术对13个供试菌株进行了实验。7个引物在13个菌株上共获得了102条多态性条带。通过聚类分析,RAPD获得的分类结果与微卫星分子标记获得的结果一致。此外,为了证明微卫星分子标记获得的条带不是假阳性,在实验中回收了No.10菌株的PCR扩增产物,进行克隆测序。测序结果显示有（TATG）n基序存在,并且达到了微卫星基序重复数量的最低限度。通过本实验可知,香菇中是存在微卫星（TATG）n基序的, 且基序的多态性可以用于香菇的遗传分类研究。     

应用RAPD技术探讨木兰科10属17种植物的遗传多样性

目的:采用RAPD技术对木兰科10属17种植物进行遗传多样性分析.方法:采用改良CTAB法提取基因组DNA,用筛选的9个引物的RAPD结果进行聚类分析,得出17种木兰科植物的聚合树状图.结果:9条RAPD引物共扩增出346条清晰稳定的条带,其中有295个多态性位点,多态百分比为85.3％,聚类分析表明,在遗传距离为0.728处17个供试品种分为3个类群.结论:中国木兰科植物品种有丰富的遗传多样性,RAPD技术可以用于木兰科植物的种间鉴别和遗传学研究.     

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.