河北省华北落叶松河北群体遗传多样性分析

以来自河北8个群体共312个华北落叶松天然个体为材料,利用10对SSR引物对群体进行扩增,所得数据用于其遗传多样性和遗传结构的研究。结果表明:10对SSR位点共检测到42个位点,平均每个位点有4.2个等位基因,位点的等位基因数(Na)为2~6个。群体平均等位基因数为3.36,Shannon指数(I)平均为0.749,观察杂合度Ho为0.405、期望杂合度He为0.423,来自河北北部的围场台子水和吉字以及兴隆雾灵山的多样性水平最高,南部的阜平群体多样性水平最低。AMOVA分子差异分析显示3%的遗传变异存在于群体间,97%的遗传变异则存在于群体内,基因分化系数Gst仅为0.028,表明华北落叶松在河北的群体分化很低。聚类结果表明河北围场两个群体为一类,蔚县、隆化和涿鹿为一类,阜平和赤城为一类,兴隆雾灵山群体距离其他较远。多样性北部群体较高,南部较低,表明华北落叶松可能的衍化方向是从北向南,印证了北部可能是起源中心的结论。     

华北落叶松种子园控制授粉子代遗传多样性分析

以华北落叶松控制授粉群体的全部子代为材料,母本相同的个体视为同一家系,利用18对SSR分子标记对7个家系257个个体进行扩增,分析其遗传多样性及其遗传分化水平。结果表明:(1)18个SSR位点共检测到72个等位基因,平均等位基因数4个,有效等位基因数(Ne)为1.247~3.411。(2)7个家系的平均有效等位基因数为2.135个,观测杂合度(Ho)为0.518,期望杂合度(He)为0.502,Shannon信息指数0.846,其中55号家系遗传多样性水平最高,56号的遗传多样性水平最低。(3)遗传分化系数(GST)为0.113,各家系群体处于中等遗传分化水平,AMOVA分析结果显示82%的遗传变异存在于家系内,18%的遗传变异存在于家系间。(4)聚类分析结果表明,55号与59号家系的遗传距离最近,具有较近的亲缘关系,49号家系与其他家系的遗传距离最远。(5)结合遗传多样性及遗传分化水平结果,估算获得选择核心家系数及核心个体数,选择5个家系均可获得96%以上的遗传多样性,对于个体数较少的家系,选择15~20个个体;对于个体数较多的家系,选择35个个体,即可获得96%以上的遗传多样性。该研究结果对华北落叶松种子园育种群体的选择及其遗传多样性的保护具有重要意义。     

华北落叶松种子园不同世代间遗传多样性变化

华北落叶松是我国华北地区营造针叶树丰产林的首选树种,我国自20世纪60年代开始营建华北落叶松种子园,现部分种子园已建至第3代。但选优导致的种子园亲子代群体间的遗传多样性水平变化情况并不清楚,其分子水平的群体遗传基础也不明确,造成高世代育种及造林工作中种质资源不清等问题。本研究利用10对EST-SSR引物,分析了河北省龙头山林场华北落叶松良种基地种子园中1代、2代、3代优树群体的遗传多样性。每对引物的等位位点数为2~5个不等。1、2、3代的平均有效等位位点数分别为1.9204个、1.81个、2.0693个,Shannon指数分别为0.7127、0.7052、0.7908,且群体中杂合子过量。结果表明,1~3代种子园群体遗传多样性水平没有明显的差异,子代群体与亲代群体间遗传分化较小,遗传变异主要存在于每代群体内,而非世代群体间。     

基于SSR标记的广东栽培益智群体遗传多样性分析

为了解广东栽培益智(Alpinia oxyphylla)群体的遗传多样性,采用SSR分子标记技术对166份种质的遗传差异进行研究。结果表明,14对SSR引物共检测到88个等位基因,每对引物检测的有效等位基因为1.198~3.279,平均2.599;Shannon多样性信息指数为0.736~1.890,平均1.107。方差分析表明20.87%的变异来自组间,79.13%的变异来自组内。基于主成分分析和遗传结构分析表明,供试166份益智样本可分为4大类群,但没有反映出形态特征的规律性。因此,益智种质资源具有较高遗传多样性,且遗传变异主要发生在群体内,群体间的遗传分化较低,且基于表型性状的类型划分和基于SSR分子标记的聚类未能实现一致性。     

内蒙古西伯利亚杏群体遗传多样性和遗传结构分析

利用27对SSR分子标记对内蒙古地区13个西伯利亚杏群体的遗传多样性和遗传结构进行分析,评价其遗传多样性水平和分化程度,为内蒙古西伯利亚杏资源的合理保护与利用提供理论依据。结果显示:(1)27对SSR引物共检测到512个等位基因(Na),各位点平均等位基因数(Na)和多态性信息含量(PIC)分别为19和0.84;物种水平上Shannons信息指数(I)和期望杂合度(He)分别为2.25和0.73。(2)群体水平上的等位基因(Na)、有效等位基因(Ne)、Shannons信息指数(I)、期望杂合度(He)和观察杂合度(Ho)分别为6.95、4.48、1.60、0.76和0.56;其中科左后旗群体遗传多样性最丰富,克什克腾旗群体遗传多样性最低。(3)基于F统计量分析的遗传分化系数(Fst)为0.12,基因流(Nm)为1.86;分子方差分析显示内蒙古西伯利亚杏群体大部分遗传变异来自群体内(92%),群体间的遗传变异仅占8%。(4)内蒙古西伯利亚杏群体遗传距离为0.04~0.67,遗传相似度为0.33~0.83;遗传相似度的聚类分析、遗传距离的主坐标分析和遗传结构分析(Structure)均将供试13个群体划分为4组。Mantel检测显示,内蒙古西伯利亚杏群体遗传距离与地理距离呈显著相关关系(r=0.453,P0.01)。研究表明,内蒙古西伯利亚杏资源具有丰富的遗传多样性,这一特性与其群体的大小、悠久的演化历史以及自身生物学特性相关;内蒙古西伯利亚杏群体间存在中等程度的遗传分化,这可能源于自然地理隔离以及近期人类活动引起的生境片段化。     

福建武夷山甜槠不同世代种群遗传多样性的SSR分析

按胸径将福建武夷山大安源样地的甜槠(Castanopsis eyrei)群体划分为成体、小树、幼苗3个世代,利用SSR分子标记对不同世代的甜槠遗传多样性及遗传分化进行分析,旨在揭示其不同世代间的遗传变异规律,为甜槠资源的保护与利用提供科学依据。14对SSR引物共检测到92个等位基因,平均每位点的等位基因数A=6.571 4,居群的平均有效等位基因数Ae=3.905 4,平均期望杂合度He=0.722 9,表明甜槠群体具有丰富的遗传变异。SSR分析显示3个世代的Ae、He、Nei指数(h)、Shannon信息指数(I)均以幼苗最高,小树次之,成体最低,幼苗的遗传多样性指数高于成体及小树,且幼苗中出现最多的稀有等位基因数,表明甜槠种群世代间的遗传多样性呈稳定上升趋势。分子方差分析(AMOVA)表明甜槠群体不同世代内、世代间均存在遗传变异,但遗传变异主要存在于世代内。SSR分析显示,甜槠不同世代间的遗传分化系数Fst=0.074 3,基因流Nm=3.115 4。甜槠不同世代间的遗传相似度以成体与幼苗最小,遗传距离以成体与幼苗间最大。基于甜槠群体SSR的研究结果,认为自然保护区的建立对物种遗传多样性的保护具有重要作用,并提出在遗传多样性保护中应注重保护成体和幼苗中稀有的等位变异。     

大鳞副泥鳅5个野生群体的遗传多样性分析

利用微卫星分子标记分析了天津地区于桥水库、大黄堡湿地、七里海湿地、团泊水库和潮白新河5个野生大鳞副泥鳅群体的遗传多样性。5个群体在12个微卫星位点共检测到98个等位基因,平均等位基因数为8.500;有效等位基因数为2.713;平均观测杂合度为0.526;平均期望杂合度为0.544。5个群体间的遗传分化指数介于0.021~0.106之间,平均遗传分化指数为0.059,属中低水平的遗传分化。AMOVA分析结果显示,在总的变异中,94.1%的遗传变异来自群体内,5.90%的遗传变异来自于群体间。根据Nei’s遗传距离所绘制的系统树显示,于桥水库、团泊水库、七里海湿地和大黄堡湿地4个群体的遗传距离相对较小聚为一支,潮白新河群体单独为一支。遗传瓶颈效应分析表明,该5个群体近期未经受遗传瓶颈效应,处于突变-漂移平衡。总体来看,天津地区5个野生大鳞副泥鳅群体的遗传多样性较高,可作为品种选育的基础群体。     

采用微卫星标记分析10个双峰驼群体的遗传变异和群体间的遗传关系

为从分子水平上对我国双峰驼(Camelus bactrianus)群体的遗传多样性、群体间遗传关系、群体遗传分化及近交情况进行全面、系统地研究,为双峰驼种质资源保护和新品种培育提供基础数据,本文利用18对微卫星引物,分析了我国9个双峰驼群体和1个蒙古双峰驼群体的遗传多样性和遗传关系。结果显示:10个群体均具有较高的遗传多样性,共检测到242个等位基因,平均等位基因数为13.44,平均有效等位基因数为4.18,平均观察杂合度(Ho)为0.5528。10个群体间存在显著的遗传分化,有9.6%的遗传变异来自群体间,90.4%的遗传变异来自群体内部的个体间。聚类分析、主成分分析和群体遗传结构分析结果都表明10个群体被分成2个明显的分支,新疆4个群体单独聚为一类,剩下的6个群体聚为一类。这一结果可能与它们的地理分布和群体间的地理屏障有关。     

濒危植物翅果油树种群的遗传多样性和遗传分化研究

利用微卫星（SSR）标记对来自山西和陕西两省的7个翅果油树（Elaeagnus mollisDiels）种群进行遗传多样性和遗传结构研究。10对SSR标记共检测到126个位点,其中多态位点114个。在物种水平上,平均多态位点百分率为90.79%,有效等位基因数（Ne）、Nei基因多样性指数（H）和Shannon多样性指数（I）分别为1.6072、0.3166、0.4603;在种群水平上,多态位点百分率为61.99%,有效等位基因数（Ne）、Nei’s基因多样性指数（H）、Shannon多样性指数（I）分别为1.5445、0.2683、0.3815。遗传分化系数GST为0.2074,表明了翅果油树种群的遗传变异主要存在于种群内。基因流Nm为1.9111〉1,说明种群间基因交流可以阻止由于遗传漂变导致的遗传分化。聚类结果表明,翅果油树种群间的遗传距离与地理距离有一定的相关性,经Mantel检验,种群的地理距离与遗传距离之间呈正相关,但未达到显著水平（p〉0.05）。结果表明,遗传多样性水平与物种本身特性和不同干扰生境有关,濒危植物并不一定表现为遗传变异水平的降低。     

中国野生大豆的遗传多样性和生态特异性分析

野生大豆（Glycine soja）是栽培大豆的祖先,为东亚特有种,大部分分布在中国。我们采用52对SSR引物和10个植物学性状,以遗传丰富度和Simpson多样性指数为指标,对来自中国3个地理生态区域涉及24个省区的196份野生大豆所构成的代表性样本的遗传变异进行了研究,以期从分子水平和表型水平两个层面上揭示中国野生大豆遗传多样性和地理生态特异性。结果表明：中国野生大豆群体SSR位点的等位基因平均丰富度（NA）和平均Simpson多样性指数（H）分别为16.1和0.852,高于栽培大豆（NA=11.4,H=0.773）,野生群体的遗传多样性明显高于栽培群体。3个地理生态群体中南方群体多样性最高（NA=12.9,H=0.842）,黄淮海群体最低（NA=11.4,H=0.805）,东北群体居中（NA=12.5,H=0.834）。群体间存在遗传分化,不同群体具有不同的特异等位基因,位点AW132402（A2连锁群）、Satt522（F）、satt150（M）、Sat_332（D1a）、Satt046（K）、sct_190（K）等的一些等位基因只在特定群体出现,表现出群体分化后的生态特异性。中国野生大豆植物学性状的群体变异丰富,平均Simpson多样性指数为0.710。地理群体间存在分化,最明显的是生育期性状的分化,反映了地理、光照和温度等生态因子的选择作用,其中南方地理群体多样性最高（H=0.671）。SSR分子标记和植物学性状所获结果相对一致,表明中国野生大豆地理群体间性状分化有其遗传分化的基础。     

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.