28种柳属植物的叶表皮微形态特征及其分类学意义

对28种表型相似、种间界限模糊的柳属植物在扫描电子显微镜下的叶表皮微形态特征进行观察,结果表明:柳属中有7种角质层蜡质纹饰,分别是平滑蜡质层、壳状蜡质层、痂状蜡质层、片状晶体、膜片状晶体、锥形纤维体和鳞片状纤维体,其中锥形纤维体和鳞片状纤维体为柳属所特有,而片状晶体和膜片状晶体为首次在柳属植物中发现;扫描电子显微镜下柳属植物叶表皮毛被的微观形态特征并不似其宏观形态(疏毛、绢毛、绒毛等)那样具有显著差异,微观形态主要表现为毛被密度、长短和卷曲方式(分为直,微弯曲和深度卷曲三种)的不同.研究表明叶表皮蜡质纹饰类型、气孔器的形态等微形态特征较为稳定,对柳属植物中表型相似的种类有很好的鉴定价值,但对组、亚属水平的界定作用不大;分布于寒冷地区和高海拔地区的柳属植物的叶表皮微形态特征相对多样,这可能是植物对寒冷环境的适应进化.     

中国木犀属植物叶表皮形态

应用光学显微镜和扫描电子显微镜对中国木犀属(Osmanthus)4组20种植物的叶表皮微形态进行了观察研究。发现该属植物叶上、下表皮细胞近相似,不规则或多边形,上表皮无气孔器,气孔器为环列型,放射状细胞型,短平列型、环列型及其过渡类型。气孔外拱盖表面多平滑,或具有颗粒状纹饰,拱盖内缘平滑,波状或不规则。气孔通常下陷,两端加厚或不加厚,周围角质膜通常增厚成环状包着气孔,上具绳索状条纹或光滑。表面蜡质纹饰常为颗粒状、鳞片状、块状、毛状、绳状或稍平滑。柊树气孔外拱盖边缘具明显的针晶,与其它种不同。腺体存在于叶的上、下表面,性状不稳定,其分类学意义不明显。木犀属叶表皮垂周壁式样、气孔器类型、气孔密度都有很大的变异,与属下分组有一定的对应性,并在组间表现出一定的演化关系。     

变豆菜属11种植物的叶表皮微形态特征研究

为探讨叶表皮微形态特征在变豆菜属植物中的系统及分类学意义,我们利用扫描电镜对变豆菜属11个种(13个居群)的叶表皮微形态特征进行了研究。结果表明,11种变豆菜属植物叶表皮微形态特征较稳定,上表皮细胞轮廓大多不清晰,初级蜡质纹饰均存在条状纹饰,表皮上均粘附着颗粒物;下表皮均存在气孔,气孔周围存在均匀分布的纹饰,气孔外拱盖表面大多有颗粒状纹饰,并且其二级纹饰类型、气孔周围纹饰、气孔外拱盖内缘纹饰等叶表皮微形态特征上存在一定差异。上述研究结果可为探讨变豆菜属类群界定及种间关系提供重要依据。     

石蒜属植物叶微形态特征研究

借助显微和扫描电镜技术对石蒜属植物叶表皮微形态特征进行了研究。利用光学显微镜和扫描电子显微镜观察了石蒜属植物的叶表皮,统计并测量了气孔类型、气孔大小、气孔密度及气孔指数等,描述了气孔及气孔外拱盖的有关特征。结果表明：石蒜属植物叶表皮气孔器为无规则型,近轴面表皮细胞形状、气孔器类型、垂周壁式样、气孔大小及气孔外拱盖内缘种间无差异或极小,表明石蒜属植物为一自然分类群。而远轴面表皮细胞形状、气孔密度、气孔指数、气孔是否下陷、气孔外拱盖是否有蜡质纹饰等种间差异较大。根据远轴面叶表皮细胞形状及叶气孔特征,研究表明：换锦花、长筒石蒜和安徽石蒜,夏水仙、乳白石蒜与红蓝石蒜,石蒜与中国石蒜具有较近的亲缘关系。因此,叶微形态特征对探讨石蒜属植物种间亲缘关系具有一定的意义。     

中国蒿属植物比较形态和解剖学研究：（1）叶表皮结构

本文通过光学显微镜和扫描电镜,观察国产菊科蒿属２亚属７组３０种代表植物成熟叶片的表皮细胞,气孔器,表皮毛的特征和气孔形状,气孔外拱盖及拱盖内缘,角质膜和蜡质纹饰。其中表皮细胞多角（边）形,大小不等,垂周壁平直,弓形,或者表皮细胞形状不规则,大小不等,垂周壁波浪状或波纹状。下表皮均有气孔,上表皮有或无气孔器,气孔器类型有无规则型,无规则四细胞型,不等细胞型,十字型,横列型和平列型。大多数种类具多细胞     

夹竹桃科植物叶表皮特征及其系统学研究

以萝藦科植物匙羹藤为对照,在扫描电镜下观察了传统上分属于夹竹桃科3亚科植物的叶下表皮特征。结果表明:(1)所观察的夹竹桃科25种植物叶下表皮特征具有一定程度的多样性,如少数物种具有表皮毛;部分角质层表面有丝状蜡质;叶下表皮纹饰有条纹状、脊状皱褶增厚、块状突起、花蕊形和较平滑等类型;气孔大小差异较大,气孔外拱盖和内缘形状分浅波状和较平滑2种类型,气孔保卫细胞极区有T型加厚和无T型加厚两种类型,气孔外拱盖与表皮细胞间分凹陷和连续两种类型等,这些叶表皮特征对夹竹桃科植物属内和属间类型的分类以及对疑难类群的划分具有重要的参考价值。(2)夹竹桃科25种植物的绝大部分种的叶表皮气孔类型、气孔外拱盖及其内缘形态基本一致,但叶表皮纹饰、气孔外缘角质层特征呈现出较高的多样性,在属内各种和属间有较大的差异。(3)萝藦科植物匙羹藤与夹竹桃科植物盆架树在气孔形状,叶片气孔外缘角质层特征、气孔外拱盖等叶表皮特征具有高度的相似性,推测这两种植物的亲缘关系可能较近,而且萝藦科与夹竹桃科中一些植物的系统位置需进一步的研究。(4)本研究结果支持仔榄树属应从山橙族中分离出来独立成族,海杧果属应从萝芙木族中独立出来的观点;但不支持新的分类方法中将糖胶树和盆架树同归属于鸡骨常山属的观点。     

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.     

东亚帚菊木族及其相关类群的叶表皮形态比较

在光学显微镜和扫描电镜下,对东亚地区帚菊木族及其南美相关类群共12属31个种的叶表皮进行了观察.研究发现气孔器普遍存在于叶的下表皮,少数种的上表皮也有分布,气孔器主要为星型和无规则型两种类型.叶表皮细胞为多边形和不规则形,垂周壁平直弓形、浅波状或波浪状.气孔器表面观为椭圆形和近圆形,气孔外拱盖内缘近平滑至浅波状,其中 Macroclinidium 较为特殊,具有双层气孔外拱盖.叶表面通常光滑无蜡质或角质,部分种叶表面具薄片状或层状蜡质.研究表明,叶表皮特征在种间一致性较高,但在属间,特别是属群和亚族间存在一定差异.     

新疆委陵菜属不同花柱组植物叶表皮微形态结构的研究

利用光学显微镜和扫描电子显微镜,观察了新疆委陵菜属5组不同花柱组10种4变种植物叶表皮的微形态特征,测量统计叶表皮毛的类型、表皮细胞的形状及大小、气孔器的分布及类型、气孔的形状、大小、密度及指数、气孔外拱盖形态及其纹饰等指标。结果显示:新疆委陵菜属10种4变种植物叶的下表皮均有气孔器的分布,形状为长椭圆形、椭圆形、宽椭圆形和近圆形;气孔器的类型多为无规则四细胞型、无规则型、围绕型和辐射型;表皮毛的类型为针状毛、带状柔毛和腺毛;表皮细胞的形状分为不规则形和多边形2种类型。研究表明,新疆委陵菜属植物表皮毛特征、叶片表皮细胞的形状、垂周壁式样、气孔器的形状类型、气孔密度指数及外围蜡质纹饰等存在差异,对属以下等级的划分有重要价值,可作为物种分类及鉴别的依据,同时也为本属一些分类群间的系统关系的探讨提供佐证。     

铃子香属的叶表皮微形态特征及其分类学意义

研究了铃子香属（Chelonopsis）及其近缘类群毛药花属（Bostrychanthera）共16种植物在光镜和扫描电镜下叶表皮微形态特征。结果表明：除等齿铃子组外,铃子香属其它种类的叶表皮细胞多为不规则形;叶表皮细胞垂周壁式样可分为平直至弓形,深波状两种类型。所有种类的气孔器都只分布于下表皮且均为不规则型;保卫细胞的形状在种间几无差别,气孔外拱盖内缘的纹饰也都近平滑,表现出了高度的一致性。角质膜有三种类型,即山脊状,长条状,具颗粒状或雪花状附属物。叶表皮细胞形态特征及角质膜类型为铃子香属内组、系或种的划分提供了重要证据。此外,两个亚属内气孔密度的不同可能与各自的生长环境有密切的关系。     

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.