豆科三属八种植物的核型及rDNA定位研究

对豆科槐属的国槐(SophorajaponicaL.)、五叶槐(S.japonicaL.f.oligophyllaFranch.)、龙爪槐(S.japonicaL.f·pendulaLoud.)、黄金槐(S.xanthanthaC.Y.Ma.)(以上均为四倍体,2n=4x=28)、红花槐(S.rubrifloraTsoong.,2n=3x=21),刺槐属的刺槐(Robiniapseudoa-caciaL.,2n=2x=22)、毛洋槐(R.hispidaL.,2n=2x=30)和紫穗槐属的紫穗槐(AmorphafruticosaL.,2n=2x=40)核型进行了分析,并应用荧光原位杂交技术进行了45SrDNA的染色体定位。槐属4个四倍体种各具4个45SrDNA位点,位于两对染色体的着丝粒周围;红花槐,3个45SrDNA位点位于第5组染色体随体区域。刺槐,4个rDNA位点位于两对随体染色体端部;毛洋槐,8个rDNA位点,4个位于两对染色体的随体及次缢痕,另4个位于两对染色体着丝粒周围。紫穗槐,6个45SrDNA位点,分别位于3对染色体的着丝粒和随体。本文对rDNA作为染色体标记在核型分析中的应用及在基因组中的分布特点进行了讨论。     

不同倍性柳枝稷45S rDNA的染色体定位研究

以3个四倍体和6个八倍体栽培品种的根尖为材料,利用荧光原位杂交技术,在核型分析的基础上,开展了不同倍性柳枝稷45S rDNA的染色体定位研究。研究结果表明,四倍体柳枝稷核型公式为2n=4x=36=32m(SAT)+4sm,且45S rDNA在四倍体柳枝稷染色体上分布稳定,位于3号染色体顶端。八倍体柳枝稷栽培品种以及同一栽培品种不同个体间45S rDNA信号分布位置和数目差异较大,可大致分为四类:第Ⅰ类为较强的45S rDNA信号分别分布于染色体两臂的顶端;第Ⅱ类为较强的45S rDNA信号位于染色体一臂内部,第Ⅲ类为较强的45S rDNA信号位于染色体一臂的顶端,第Ⅳ类为较弱的45S rDNA位于染色体一臂内部。八倍体柳枝稷不同栽培品种以及同一栽培品种不同个体间45S rDNA信号复杂性的成因可能与染色体同源重组以及染色体结构变异密切相关。     

薏苡45S和5S rDNA的染色体定位研究(简报)

通过荧光原位杂交的方法确定了45S和5S正NA序列在薏苡前中期染色体上的位置.尽管具有20条染色体的薏苡是四倍体植物,但它的基因组中只有一个45S和5S rDNA位点.根据薏苡前中期染色体的核型,确定45S rDNA序列位于薏苡第2号染色体短臂上的次级缢痕区和随体上,5S rDNA序列位于第7号染色体长臂靠近着丝粒处,5S rDNA位点到着丝粒的百分距离是29.13±1.76.     

基于荧光原位杂交的藜属植物核型分析

为精确地识别藜属植物染色体组的核型特征,该文研究了4种来自青海高原的野生藜属植物(灰绿藜、藜、菊叶香藜及杂配藜)和1种从美国引进的栽培藜麦品种PI614932-HX(3)基于染色体荧光原位杂交(rDNA FISH)的核型。利用5S rDNA和45S rDNA对5种藜属植物有丝分裂中期的染色体进行FISH研究。藜属植物的核型分析结果表明:(1)藜属植物中存在二倍体(2n=2x=18)和四倍体(2n=4x=36)两种倍性,藜麦和灰绿藜为四倍体,其余3种为二倍体。(2)藜麦、灰绿藜、藜、菊叶香藜及杂配藜的核型公式分别为2n=4x=36=34m(2AST)+2sm,2n=4x=36=32m(4AST)+4sm,2n=2x=18=16m(4AST)+2sm,2n=2x=18=18m及2n=2x=18=16m+2sm。(3)染色体由大部分的中部着丝粒染色体(m)和少部分近中部着丝粒染色体(sm)组成。(4)核型类型除了菊叶香藜为1B以外,其余均属于2B类型。(5)在藜麦、灰绿藜及藜中具有分布位置不同、数量不等的双随体。5S rDNA、45S rDNA FISH结果表明:(1)藜麦和灰绿藜的染色体上存在2对5S rDNA位点和1对45S rDNA位点,藜、杂配藜的染色体上存在1对5S rDNA位点和1对45S rDNA位点,菊叶香藜的染色体上只存在1对5S rDNA位点。(2)5S rDNA和45S rDNA位点均位于染色体的短臂上。该研究首次获得了藜属植物基于5S rDNA和45S rDNA荧光原位杂交核型,为藜属植物亲缘关系研究和细胞生物学研究提供了分子细胞遗传学依据。     

亚比棉基因组原位杂交及核型分析

亚比棉异源四倍体是山西农业大学棉花育种组于上个世纪80年代用A染色体组亚洲棉(Gossypium.arboreum)(迁西小黑籽)与G染色体组野生棉比克氏棉(G.bickii)杂交成异源二倍体后,又经过加倍而获得的.亚比棉异源四倍体不仅育性得到恢复、结铃正常,而且成功地将比克氏棉的优异性状--种子腺体延缓形成转育到亚比棉中.这为实现棉花综合利用和提高抗虫性创育了新的育种材料.在随后的多年中,山西农业大学棉花育种组对亚比棉异源四倍体进行了广泛的细胞形态学研究,对其核型做了分析.然而,仅依据形态学和普通的核型图像,还不能确定该异源四倍体棉种中比克氏棉G染色体(亚)组在核型中的表现.该文以比克氏棉gDNA为探针,亚比棉异源四倍体根尖体细胞染色体为靶细胞染色体,封阻材料为亚洲棉(迁西小黑籽),进行亚比棉基因组原位杂交(Genome in situ hybridization,GISH)及核型分析.从获得的图像中可以清晰地发现有52条染色体,其中有/无杂交信号的各一半,这直观地证实了人工复合亚比棉杂交种确为异源四倍体,而且是双二倍体.A亚组与G亚组染色体长度存在交替排列.亚比棉异源四倍体基于GISH图像的核型公式为2n=4x=52=46m(4sat)+6sm(4sat).A亚组和G亚组染色体上各有2对随体.G亚组染色体中至少有5对双重显色明显的染色体,意味着可能有A亚组染色体的交换,而A亚组染色体中只观察到或多或少的探针红色荧光信号,由于分辨率不够而难于定量分析.进一步以45SrDNA为探针,以鲑鱼精DNA作为封阻DNA,对亚比棉异源四倍体进行45SrDNA-FISH,实验表明,亚比棉异源四倍体有14个NOR(核仁组织区)信号,说明亚比棉异源四倍体有14个随体,即7对随体.比克氏棉对亚洲棉的GISH结果显示,在有亚洲棉DNA封阻的条件下,亚洲棉靶细胞染色体无任何杂交信号,说明比克氏棉与亚洲棉染色体之间不存在较大的同源或相似序列.     

中国17种蔷薇属植物45S和5S的rDNA分布研究

为了探寻蔷薇属植物亲缘关系及系统发育研究的分子细胞遗传学证据,该研究采用双色FISH(荧光原位杂交)技术,对原产中国7个组的17种蔷薇属植物的45S和5S rDNA进行了定位分析。结果表明:(1)多数蔷薇属植物1组染色体对应1个45S rDNA位点和1个或2个5S rDNA位点,偶尔出现1~2个rDNA位点的丢失,但复伞房蔷薇(Rosa brunonii)的1组染色体对应了2个45S rDNA位点。(2)二倍体的蔷薇属植物至少有1对5S rDNA位点与45S rDNA位点共定位,而四倍体材料的5S rDNA位点与45S rDNA位点没有共定位,但所有四倍体材料均至少有1种rDNA信号纯合,表明它们应为二倍体直接加倍产生的同源四倍体。(3)绝大多数材料45S rDNA位于染色体短臂、5S rDNA位于染色体长臂,但缫丝花(R. roxburghii f. roxburghii)有1个5S rDNA信号位于染色体的短臂上,表明它与蔷薇属其他种的亲缘关系较远。(4)阿克苏地区和伊犁地区的疏花蔷薇的核型不同,且45S和5S rDNA的数量和位置不同,分子细胞遗传学证据也支持阿克苏地区的疏花蔷薇应为疏花蔷薇的新变种。(5)该研究中共有8个二倍体和6个四倍体蔷薇属植物的双色FISH为首次报道。研究认为,无论二倍体还是四倍体蔷薇属植物中出现的异形同源染色体、rDNA信号位置在同源染色体上的差异以及rDNA信号的增加和丢失,可能都与染色体结构变异和染色体重组有关,在分子细胞遗传学水平上证明染色体结构变异和染色体重组在蔷薇属植物演化过程中具有重要的作用。     

不同地域乌拉尔甘草基因组的FISH分析与染色体识别

在核型分析与染色体识别基础上,分别以番茄45S和5S rDNA为探针,对3种不同地域的乌拉尔甘草进行FISH分析.结果表明:内蒙古鄂托克前旗的乌拉尔甘草核型公式为2n=2x=16=6m+10sm (2SAT),新疆阿勒泰地区的乌拉尔甘草核型公式为2n=2x=16=4m+12sm(2SAT),内蒙古喀喇沁旗乌拉尔甘草核型公式为2n=2x=16=4m+12sm(2SAT);其第8染色体均带有随体.3种乌拉尔甘草基因组内均有1对5S rDNA和1对45S rDNA杂交位点.核型分析显示,5S rDNA杂交位点均位于第2染色体的短臂部位,45S rDNA杂交位点均位于第8染色体的次缢痕和随体部位.45S与5S rDNA在3种乌拉尔甘草中期分裂相上的位点数和分布情况高度一致,表明来自3种不同地域的乌拉尔甘草在染色体结构水平上没有较大的分化.     

FISH分析栽培高粱×拟高粱、甜高粱×拟高粱的染色体行为

采用荧光原位杂交技术对45S rDNA在栽培高粱×拟高粱、甜高粱×拟高粱F1的有丝分裂和减数分裂染色体进行定位研究。在有丝分裂中期染色体上2个杂种分别检测到2个杂交信号, 在减数分裂粗线期、终变期、中期Ⅰ染色体上45S rDNA位于一个二价体上, 说明这两个杂种携带45S rDNA的染色体为同源染色体。根据45S rDNA位点随细胞减数分裂过程的位置变化, 表明这两个杂种染色体配对行为正常, 平均构型为2n=2x=20(10Ⅱ), 证明45S rDNA可作为染色体的一个识别指标间接地观察细胞减数分裂过程染色体的变化行为。     

菠菜rDNA及端粒多色荧光原位杂交分析

以拟南芥25S rDNA、5S rDNA以及端粒序列为探针对菠菜的中期染色体进行了多色荧光原位杂交分析, 其中25S rDNA用生物素标记, 端粒序列用地高辛标记, 5S rDNA用生物素和地高辛共同标记。杂交结果显示, 菠菜中期染色体25S rDNA杂交位点为6个, 分别位于3号、5号和6号染色体的随体部位; 5S rDNA杂交位点为4个, 分别位于3号和5号染色体长臂, 端粒序列杂交位点位于6号染色体端部以及其余染色体的端部和着丝粒部位。     

番茄的CPD带型和45S rDNA位点的鉴别

采用CPD（PI和DAPI组合）染色对番茄减数分裂粗线期和有丝分裂中期染色体进行了显带分析,随后用两种不同的45S rDNA克隆在相同的分裂相进行了荧光原位杂交定位分析。CPD染色在8条粗线期染色体上显示出了10条红色的CPD带纹,在6对有丝分裂中期染色体上显示出了12条CPD带纹。有丝分裂中期染色体上的CPD带纹与粗线期染色体上显著的带纹具有对应性。用改良的CPD染色程序清晰而稳定地显示出这些特征性的CPD带纹为番茄的染色体,特别是有丝分裂中期染色体提供了新的识别标记。用番茄的一个45S rDNA克隆进行的荧光原位杂交,不仅在位于2号染色体短臂的随体上显示了强的杂交信号,而且在粗线期染色体的5个CPD带区或有丝分裂中期染色体的4对CPD带区显示了弱的杂交信号。然而,用来自小麦的45S rDNA克隆pTa71进行的原位杂交却只在随体上显示了杂交信号。鉴于所用的两个45S rDNA克隆在序列上的差异,推断在番茄基因组中只有随体含有45S rDNA单位的编码区,即番茄只有一对45S rDNA位点。     

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.