孑遗植物中华桫椤2个群体遗传多样性的ISSR分析

为阐明小尺度范围内濒危物种孑遗植物中华桫椤种群的遗传多样性,保护和恢复种质资源,本文采用ISSR分子标记技术对云南屏边大围山的大围山红旗水库和大围山山谷2个中华桫椤种群的遗传多样性进行分析。结果表明用从100个随机引物中筛选出的20个能高产稳定扩增的ISSR引物对2个群体共57个样品进行扩增,共获得132个可分析位点,其中大围山红旗水库的多态性位点83个,占62.87%,而大围山山谷的多态性位点97个,多态位点百分率(P)为73.48%,两者Nei's基因多样性分别为0.2614和0.2832,Shannon's信息指数分别为0.3762和0.4135,两个种群的遗传分化系数Gst为0.0701,分析结果表明中华桫椤种群内的遗传多样性较高,但两种群间的遗传分化不明显。本研究结果将对中华桫椤自然群体的保育和管理具有重要意义。     

濒危植物蒙古扁桃不同地理种群遗传多样性的ISSR分析

采用 ISSR 分子标记对蒙古扁桃(Prunus mongolica)6个自然种群的遗传多样性进行了分析.12条ISSR引物共扩增出200条带,其中199条具多态性,多态位点比率为99.5％.在种群水平上多态位点百分率平均为55.3％.Nei's基因多样性、Shannon's信息指数在种群水平上分别为0.3241和0.4875,在物种水平上分别为0.3105和0.4722.根据基因分化系数,测得基因流值Nm为0.8266.UPGMA聚类分析结果表明:乌海千里沟种群和东升庙那仁乌拉种群遗传一致度最大,遗传关系最近.ISSR检测结果表明,包头萨拉齐种群的遗传多样性最丰富,在制定原位种质保护计划时,应优先保护包头萨拉齐周边地区的蒙古扁桃.     

二色胡枝子遗传多样性ISSR分析

利用ISSR分子标记技术对二色胡枝子的遗传多样性进行分析,16个ISSR引物共扩增出229条带,多态性条带209条,多态性比率为91%,居群的平均多态性位点比率为68.24%,胡枝子总遗传多样性Ht为0.392,Shannon指数为0.576,群体间基因分化系数Gst的变动范围非常大,平均值为0.2434,居群间基因流Nm为1.052。种群内的基因多样性占总群体的75.66%,种群间占24.34%,表明二色胡枝子种群具有丰富的遗传多样性,在育种上具有很大的遗传潜力。根据居群间遗传相似系数聚类,14个居群被聚成3大类群,且居群的遗传多样性参数与其地理、生态因子相关均不显著,遗传多样性无明显的地域性分布格局。     

不同干扰生境下河口莲座蕨遗传多样性分析

该研究利用 ISSR 分子标记,对不同生境下的6个河口莲座蕨种群进行遗传多样性分析。结果表明：从44条ISSR引物中筛选出8条能够扩增出清晰、稳定条带的引物,对6个河口莲座蕨种群进行基因组 DNA扩增,共扩增出144条带,其中多态性条带119个,多态性条带比率为93.7％,Nei’s遗传多样性指数(H)为0.296,Shannon多样性指数(I)为0.457,遗传分化指数(Gst)为0.1520,种群遗传一致度和遗传距离分别为0.9138~0.9548和0.0584~0.0901;UPGMA聚类分析表明,种群间遗传距离与空间距离和生境类型有关。河口莲座蕨在不同干扰程度的生境中,种群具有高水平的遗传多样性,一定强度或频率的干扰生境中,种群遗传多样性较高,与海拔、坡度和坡向无相关性。     

杜鹃红山茶遗传多样性的ISSR分析

运用ISSR分子标记技术,利用筛选的10条ISSR引物,对珍稀濒危植物杜鹃红山茶(Camellia changii Ye)2个亚种群60个单株的遗传多样性进行了研究。结果表明:物种水平上的多态位点百分率(PPB)为55.29%,Nei’s基因多样性指数(H)及Shannon多态性信息指数(I)分别为0.2191和0.3215。种群间的遗传分化系数(GST)仅为0.0922。研究结果揭示了杜鹃红山茶的遗传多样性较低,亚种群间遗传分化较小。小种群和人为活动干扰是杜鹃红山茶现存种群的主要限制因素。影响杜鹃红山茶种群发展的其它因素亟需进一步研究。     

不同成花量金花茶花果期果枝叶内源激素的变化

该研究采用ISSR分子标记,对黄枝油杉7个自然种群的遗传多样性进行了分析。结果表明：用12条ISSR引物对218个黄枝油杉个体进行扩增,共扩增出125个位点。在物种水平上,多态性位点百分数( PPL)为100.00％,Shannon信息多样性指数( I)为0.4177,Nei’ s基因多样性指数( H)为0.2666；在种群水平上,多态性位点百分数(PPL)在71.20％~92.00％之间,平均值为80.69％,Shannon信息多样性指数(I)在0.3273~0.3886之间,平均值为0.3548,Nei’ s基因多样性指数( H)在0.2139~0.2478之间,平均值为0.2291。这说明黄枝油杉在物种水平和种群水平上均显示出较高的遗传多样性。 Nei’ s遗传多样性分析( Gst＝0.1433)和AMOVA分析(Φst＝17.91％)表明,黄枝油杉的遗传变异主要存在于种群内,种群间的遗传分化程度较低,种群间保持一定的基因交流( Nm＝2.9890>1)。 Mantel分析显示,黄枝油杉种群间的遗传距离和地理距离之间不存在显著的相关关系( r＝0.4567, P＝0.0610>0.05)。     

基于简化基因组技术的云南蓝果树群体遗传分析

极小种群野生植物云南蓝果树是国家和云南省实施极小种群野生植物保护工程的代表性物种。为有效保护其遗传资源,本研究通过二代测序技术,对其进行简化基因组测序,开发一批特异性高的单核苷酸多态性标记,分析现存群体的遗传结构和遗传多样性。经过遗传变异检测,本次研究中共获得SNP位点98 498个,通过样品最低测序深度>2,样品缺失率<0.5,次要基因型频率（MAF）>0.05筛选以后,得到有效SNP位点6 309个。基于过滤后的SNP,运用生物信息学分析方法,对云南蓝果树完成了群体的遗传分析,其中：系统进化树分析将云南蓝果树划分为3大类,研究分析了云南蓝果树各分类的私人等位基因数目（Private）、平均观测杂合度（H_o）、平均期望杂合度（H_e）、核苷酸多样性（π）和平均近交系数（F_IS）5个遗传多样性参数;群体结构和主成分分析进一步证明了,云南蓝果树现存植株之间亲缘关系较远,遗传多样性差异较大,具有很高的遗传资源保存价值。本研究结果将为基于遗传管理的云南蓝果树就地保护、遗传资源保存和种群重建等保护工程提供科学依据。     

黄枝油杉遗传多样性的ISSR分析

该研究采用ISSR分子标记,对黄枝油杉7个自然种群的遗传多样性进行了分析。结果表明:用12条ISSR引物对218个黄枝油杉个体进行扩增,共扩增出125个位点。在物种水平上,多态性位点百分数(PPL)为100.00%,Shannon信息多样性指数(I)为0.417 7,Nei’s基因多样性指数(H)为0.266 6;在种群水平上,多态性位点百分数(PPL)在71.20%~92.00%之间,平均值为80.69%,Shannon信息多样性指数(I)在0.327 3~0.388 6之间,平均值为0.354 8,Nei’s基因多样性指数(H)在0.213 9~0.247 8之间,平均值为0.229 1。这说明黄枝油杉在物种水平和种群水平上均显示出较高的遗传多样性。Nei’s遗传多样性分析(Gst=0.143 3)和AMOVA分析(Φst=17.91%)表明,黄枝油杉的遗传变异主要存在于种群内,种群间的遗传分化程度较低,种群间保持一定的基因交流(Nm=2.989 01)。Mantel分析显示,黄枝油杉种群间的遗传距离和地理距离之间不存在显著的相关关系(r=0.456 7,P=0.061 00.05)。     

异色瓢虫不同地理种群的ISSR种群多样性分析

异色瓢虫Harmonia axyridis(Pallas)在亚洲地区是一种重要的捕食性天敌昆虫,但是当引入到欧美后,对当地的物种产生了威胁.本文用ISSR技术对两个中国本地种群和一个引入美国的种群进行了种群多样性以及种群分化的分析.8条ISSR引物共扩增出105条带,其中多态性条带比率为96.19%.Nei's多样性指数、Shannon信息指数、多态性条带比率,在中国种群与美国种群中均非常接近,种群分化不明显(G_(st)=0.042).AMOVA分析显示种群多样性主要来源于种群内部,种群问的基因流非常强(N_m=5.537).基于Nei's多样性构建的聚类结果显示ISSR是一种快速有效的研究异色瓢虫种群多样性关系的技术.     

中国桃蛀螟不同地理种群的遗传多样性

本文应用ISSR分子标记技术对中国桃蛀螟Conogethes punctiferalis 11个地理种群的基因组DNA进行了遗传多样性和遗传分化分析。从34条引物中筛选出6条用于ISSR多态性分析, 共扩增出211条带, 其中209条具多态性, 总的多态性条带百分率为99.05%。11个种群的遗传距离在0.0059~0.0237之间, Nei氏基因多样性指数为0.1750, Shannon信息指数为0.2966, 遗传分化系数为0.053, 基因流高达8.8724。结果提示中国桃蛀螟地理种群因基因流水平较高而种群遗传分化水平保持较低。     

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.