鹿药属植物叶表皮特征及其系统学意义

采用光学显微镜和扫描电镜对鹿药属12种植物的叶表皮进行了观察,首次报道了12种鹿药属(Sm ilaci-na)植物叶表皮的微形态特征。结果表明:气孔器普遍存在于叶的下表皮,少数种的上表皮也有分布,均为不规则形。叶表皮细胞形状为多边形或不规则形,垂周壁式样可区分为近平直、浅波状和波状。在扫描电镜下,叶表皮气孔器外拱盖内缘为近平滑、浅波状或波状;角质膜条纹状,有的条纹隆起,有的条纹上附有颗粒和晶簇。气孔器的分布、气孔器外拱盖内缘形态以及角质膜等特征对该属部分种的区分具有一定的参考价值。     

安徽产大戟属植物叶表皮微形态

利用光镜和扫描电镜对安徽7种大戟属(Euphorbia)植物叶表皮进行了观察。发现该属7种植物叶表皮细胞为不规则形或多边形,垂周壁一般为平直、浅波状、深波状;气孔器通常为无规则型,有的种类叶表皮具单细胞毛或多细胞毛,表皮毛在电镜下具瘤状突起的纹饰。在扫描电镜下,角质层纹饰多具鳞片或颗粒等特征,种间有细微差别。结果表明该7种植物叶表皮微形态有明显差别,这些表皮特征有助于识别一些在外部形态较相近的种类。     

贯众属的叶表皮特征

对贯众属(Cyrtomium)19种植物和近缘类群的15种植物的叶表皮形态特征进行了光学显微镜观察,并对包括贯众属3个亚系的模式种在内的12个种进行了扫描电镜观察。结果显示贯众属的叶表皮细胞为多边形或不规则形,垂周壁近平直、弓形、浅波状、波状至深波状。贯众属的气孔器分布于叶片下表皮,有无规则型、横列型和极附型三种类型,其中无规则型是主要的气孔器类型。气孔器表面观为宽椭圆形,长椭圆形,稀为近圆形,气孔外拱盖内缘近平滑、浅波状至啮齿-浅波状。大多数种类叶片表面角质膜具条纹,并常有条状隆起,或具颗粒等附属物。目前研究未发现可作为邢公侠二系四亚系诊断特征的明显的叶解剖特征。     

贯众属的叶表皮特征

对贯众属（Cyrtomium）19种植物和近缘类群的15种植物的叶表皮形态特征进行了光学显微镜观察,并对包括贯众属3个亚系的模式种在内的12个种进行了扫描电镜观察。结果显示贯众属的叶表皮细胞为多边形或不规则形,垂周壁近平直、弓形、浅波状、波状至深波状。贯众属的气孔器分布于叶片下表皮,有无规则型、横列型和极附型三种类型,其中无规则型是主要的气孔器类型。气孔器表面观为宽椭圆形,长椭圆形,稀为近圆形,气孔外拱盖内缘近平滑、浅波状至啮齿-浅波状。大多数种类叶片表面角质膜具条纹,并常有条状隆起,或具颗粒等附属物。目前研究未发现可作为邢公侠二系四亚系诊断特征的明显的叶解剖特征。     

中国棱子芹属植物叶表皮微形态特征及其系统学研究

采用光学显微镜和扫描电镜对棱子芹属(Pleurospermum)11种植物的叶表皮微形态特征进行了观察研究.结果表明:(1)显微观察显示,气孔器普遍存在于叶的下表皮.少数种的上表皮也有分布,多为无规则型;叶表皮细胞形状为多边型或不规则形.垂周壁式样可区分为近平直、平直-弓形、浅波状和波状.(2)扫描电镜观察显示,叶表皮气孔器外拱盖内缘为近平滑、浅波状或波状;角质膜条纹状,有的条纹隆起,有的条纹上附有颗粒和晶簇.(3)气孔器的分布、气孔器外拱盖内缘形态以及角质膜等特征对该属部分种的区分有一定的参考价值.(4)结合外部形态特征,推测康定棱子芹应作为种一级分类群.松潘棱子芹与宝兴棱子芹的亲缘关系比较近.     

中国梅花草属植物的叶表皮特征及其系统学意义

利用光学显微镜和扫描电镜对梅花草属Parnassia 30种植物的叶表皮进行了观察。结果表明:气孔器普遍存在于叶的下表皮,少数种的上表皮也有分布,均为无规则型。叶表皮细胞形状为多边形或不规则形;垂周壁式样可区分为近平直、浅波状和波状。在扫描电镜下,叶表皮气孔器外拱盖内缘为近平滑、浅波状或波状;一些种的保卫细胞两端有加厚;角质膜条纹状,有的条纹隆起,有的条纹上附有颗粒或小孔穴。气孔器类型及下表皮细胞形状的一致性表明梅花草属是一个自然分类群;sect. Saxifragastrum叶表皮特征具有多样性显示该组可能是一个复合群;突隔梅花草P. delavayi属于subsect. Xiphosandra,其气孔下陷,与其细胞学特征相似,支持独立为一组;此外,气孔器的分布、保卫细胞两端加厚、气孔器外拱盖内缘形态以及角质膜等特征对该属部分种的区分有一定的参考价值。     

中国西南地区独活属植物叶表皮微形态特征及其系统学意义

利用光学显微镜和扫描电镜对中国西南地区独活属16种1变种植物(分隶于中国独活属的全部4个组)的叶表皮微形态进行了观察,测量并统计气孔器大小、密度和气孔指数,并用统计学方法对远轴面气孔器长轴进行显著差异性分析.结果显示:无规则型气孔器普遍存在于所有研究类群的叶远轴面及个别类群叶近轴面,气孔器的分布和密度具有种间特异性.表皮毛普遍存在于远轴面及大部分类群近轴面,长短和覆盖密度因种而异.近轴面表皮细胞为多边形或者不规则形,垂周壁平直、浅波状或波状;远轴面表皮细胞形态多不规则形,表皮细胞垂周壁浅波状或波状.在扫描电镜下,叶表皮气孔器外拱盖内缘为近平滑、浅波状或波状;角质膜条纹状,有的附有颗粒状、鳞片状蜡质等结构.气孔器外拱盖形态以及蜡质类型是稳定的鉴别特征.研究表明独活属植物叶表皮特征存在较大的种间差异,对独活属的系统分类及进化研究具有重要意义,文中对叶表皮特征在独活属植物分类处理中的应用及系统进化问题等进行了讨论,并建立了以叶表皮微形态特征为依据的分类检索表.     

中国红豆属植物的叶表皮形态学

用光学显微镜和扫描电子显微镜观察了红豆属(Ormosia)35种的叶表皮形态,这些植物的叶上下表皮细胞为不规则形或多边形,垂周壁有平直、弓形、浅波状或深波状,表皮细胞形状和垂周壁在种间有一些差异。气孔仅存在于下表皮,形状为椭圆形或卵形,以平列型为主;此外还有其他类型的气孔,如长脐红豆、海南红豆等的气孔为不规则形、不等型;少数种类如亮毛红豆、茸荚红豆等的气孔不明显。气孔外拱盖光滑,呈浅波状、波状或不明显,气孔内拱盖光滑、近光滑、浅波状或不明显;蜡被近光滑、颗粒状、鳞片状、条纹状或结网状;多数种具毛被。叶表皮与气孔器特征可作为区分种、变种或亚种的依据。叶表皮微观形态特征支持红豆属成为一个自然类群。     

安徽产两种山罗花属植物及其居群叶的微形态比较

利用离析法、扫描电镜和石蜡切片法对安徽产2种3居群山罗花属植物的叶进行了微形态比较研究,结果表明：该属植物叶表皮细胞形状为不规则形,垂周壁呈波状、深波状至重波状;表皮细胞内含叶绿体;角质层具条状纹饰;表皮上有表皮毛和腺毛分布,扫描电镜下表皮毛具瘤状突起的纹饰;栅栏组织只有1层,排列比较疏松,海绵组织有发达的胞间隙;气孔器多为无规则型,极少数仅有一个副卫细胞,仅分布于下表皮,扫描电镜下气孔外拱盖内缘近光滑或浅波状。2种植物在垂周壁式样、表皮毛密度、气孔器长宽比、栅栏组织和海绵组织的厚度比以及中脉的结构特征等具有明显的差异,而山罗花3居群间的差异不明显。     

中国柴胡属植物叶表皮特征及系统学意义

利用光学显微镜和扫描电镜对我国柴胡属（Bupleurum L．）13种（含1变种）植物的叶表皮进行了观察,首次报道了它们的微形态特征。结果表明：除了大叶柴胡（B．longiradiatum Turczaninow）气孔器仅存在于下表皮,其余12种柴胡的上、下表皮都存在气孔器,气孔器类型包括不规则型和不等型两种。叶表皮细胞形状为多边形或不规则型,垂周壁式样可区分为平直一弓形、浅波状。保卫细胞壁加厚明显,极端联合形成极层结构。在扫描电镜下,气孔器内陷于表皮细胞间。角质膜条纹状,有的条纹隆起,有的条纹上附有蜡质胶状分泌物和鳞片。光镜和电镜下叶表皮柴胡属微形态表现出相当高的多态性;而在特定的分类群中,又表现为高度的一致性,为种间分类提供了新的证据。     

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.