内蒙古典型草原禾本科植硅体形态

运用地层中植硅体组合解释过去草原植被及气候变化的关键之一,是要了解研究区现代植硅体形态及表土植硅体组合与现代植被的关系。文中研究内蒙古典型草原禾本科植物根、茎、叶、芒以及种子等不同部位的植硅体,对其中的12种主要禾本科植物叶表皮短细胞硅酸体进行分类及统计。研究表明：内蒙古典型草原禾本科叶表皮短细胞硅酸体可分为8种特殊形态类型。C3植物早熟禾亚科的叶表皮短细胞硅酸体形态多样。几乎所有早熟禾亚科都能产生圆型硅酸体,以贝加尔针茅(85．5％)、大针茅(89．7％)、克氏针茅(90％)以及芨芨草(96．6％)中的圆型硅酸体含量最丰富。针茅哑铃型主要见于针茅植物叶表皮短细胞中,克氏针茅的针茅哑铃型含量相对较高。羊草中未见针茅哑铃型硅酸体。浴草、披缄草叶表皮短细胞硅酸体以齿型为主,分别含87．3％和57．2％,齿型在硬质早熟禾中也占一定比例。沙生冰草中的脊圆型占优势,含74．4％。C3植物早熟禾亚科的叶表皮短细胞产生的截锥型硅酸体含量较少。C4植物虎尾草亚科中的糙隐子草叶表皮短细胞硅酸体以黍哑铃型、简单哑铃型、鞍型为主;黍亚科狗尾草则以黍哑铃型占优势(82．9％)。     

永德大雪山中山湿性常绿阔叶林植物区系的初步研究

中山湿性常绿阔叶林是永德大雪山亚热带山地植被垂直带上最具特征性的植被类型,也是该地区面积最大、保存最为完整、最有保护价值的植被类型。从该类型植被中219种常见和优势植物的种类结构分析看,只有热带亚洲成分、中国-喜马拉雅成分及中国特有成分能够贯穿于乔木Ⅰ、Ⅱ、Ⅲ层,灌木层,草本层和层外植物各层次之中;其区系成分以中国-喜马拉雅和中国特有成分占优势,同时热带亚洲成分也占有相当的比例,说明其区系具有亚热带向温带过渡的性质;而中国特有种的进一步分析亦表明其区系的过渡性质。这表明永德大雪山处于中国-喜马拉雅森林植物区系和热带亚洲植物区系的分界面上,其植物区系的过渡特征非常明显。通过永德大雪山中山湿性常绿阔叶林与邻近地区同类型植被的优势种和主要伴生种的比较,我们初步认为该地此类森林植被环境更“温湿”。     

香港壕涌遗址孢粉、植硅石组合及其环境考古

香港壕涌遗址孢粉、植硅石组合表明：自新石器时期以来该遗址周围植被以热带-亚热带蕨类植物为主;草本植物以禾本科、莎草、藜科等主为;在遗址附近的高地及山坡上生长了常绿阔叶林,其成分包括：阿丁枫香属（Altingia）、栲属（Castanopsis ）、常绿栎（evergrenn Quercus）、棕榈（Palmae）等;植被面貌是人类活动干扰的结果。新石期时期,遗址受海水影响,人类活动以采集、捕捞为主;唐宋时期,禾本科花粉及典型水稻硅酸体的大量出现,反映了稻作农业的发展及人类生存方式的改变。     

莎草科植物硅酸体的研究

作者对国产莎草科１３个属６５种植物中成熟果实和叶片的硅酸体形态、发育和分布进行了系统的分析研究,结果表明：（１）莎草科植物硅酸体特征同其形态系统发育特征具有明显的相关性。所有莎草科植物的成熟果实表皮均具发育典型的帽状莎草Ⅰ型硅酸体,而在叶片上普遍发育莎草Ⅱ型硅酸体;说明莎草科是一个自然类群。（２）莎草科植物果实硅酸体特征在属间差异较大,在属下等级分类群之间差别一般较小;因而在高级分类群的划分上,具有较高的系统分类意义。（３）莎草Ⅱ型硅酸体相在种间及种下水平的分类研究中有较大的意义。根据莎草科植物莎草Ⅰ型果实硅酸体的形态特征,可以将这１３个属划分为三类：１、这种类型包括嵩草属（Ｋｏｂｒｅｓｉａ）,苔草属（Ｃａｒｅｘ）,扁穗苔属（Ｂｌｙｓｍｏｃａｒｅｓ）;２、包括羊胡子草属（Ｅ ｒｉｏｐｈｏｒｕｍ）,荸荠属（Ｅｌｅｏｃｈａｒｉｘ）,扁穗草属（Ｂｌｙｓｍｕｓ）,飘佛草属（Ｆｉｍｂｒｉｓｔｙｌｉｓ）,莎草属（Ｃｙｐｅｒｕｓ）,水莎草属（Ｊｕｎｃｅｌｕｓ）,水蜈蚣属（Ｋｙｌｉｎｇａ）;３、包括珍珠茅属（Ｓｃｌｅｒｉａ）,砖子苗属（Ｍａｒｉｓｃｕｓ）,扁莎草属（Ｐｙｃｒｅｕｓ）。     

无量山中山湿性常绿阔叶林及其植物区系的初步研究

无量山中山湿性常绿阔叶林是其垂直带上最具特征性的植被类型。从这类森林中２３１种优势和常见植物的种类结构分析看,只有热带亚洲成分、东亚中的中国－喜马拉雅成分、和中国特有成分贯穿乔木Ａ、Ｂ层,灌木层,草本层和层外植物几大类中;而中国特有种的进一步分析表明了它的区系成分的亚热带性质,温带性质不是很显著。该地这类森林与云南同类型植被有诸多方面的相似性,但是大致上每一个大的山头有一套植物种类成分,而以各种石栎树种加以区分,其它重要伴生种及伴生种的各类组合千差万别。对这类森林中３５个特有种的分析显示区系平衡点邻近范围有较大的物种分化水平;它们所隶属的属的分析表明,这类植被的温带性质又较该地整体水平为强;它们的近缘种分布区域对无量山此类森林与这些区域相应类型植被的区系联系和分化有一定指示意义     

中国东北自然土壤剖面中植硅体的垂直分布规律

本研究利用湿式灰化法提取了东北地区23个自然土壤剖面的植硅体,分析、探讨了植硅体在土壤剖面中的垂直分布规律及其影响因素。首先,东北地区自然土壤剖面中植硅体的垂直分布大体呈表层(腐殖质层)富集,但由于土壤理化性质的差异,仍可进一步大体划分为表层相对聚积型(如黑钙土和白浆土)和均匀分布型(如暗棕壤、黑土和冲积土)。其次,土壤原始成土过程、土壤pH等显著影响着土壤剖面中植硅体的分布。我们的研究发现:①基于土壤原始成土过程的分析,推测在土壤剖面(尤其是母质为岩石风化物的土壤)母质层中植硅体可能是不存在的;②土壤有机质影响了土壤剖面中植硅体的多少,依据土壤植硅体浓度-有机质方程得出的土壤剖面特定深度的模拟植硅体总浓度均明显小于其实测值;③土壤pH是影响土壤中植硅体分布的重要因素之一,剖面下层pH较高,保存程度较差的植硅体所占比例却较大;④不同土壤发生层植硅体的大小组成不同,越向深处,小型植硅体所占比例越大。总之,自然土壤剖面中不同土壤发生层植硅体的组成和含量存在差异,推测自然土壤剖面中可能存在植硅体的垂向迁移,但仍需进一步验证。     

脂肪酮分子在第四纪古土壤中的分布及其古气候意义

广泛分布于地质体并受成土作用改造的α-正构脂肪酮在全球变化中的应用比较少见．远不如其他脂肪族化合物（如正构烷烃、脂肪酸等）那样普遍。文章以位于长江中下游红土和黄土交接地带的安徽宣城红土剖面和黄土高原的黄土剖面为研究对象．探讨α-正构脂肪酮的分布规律。α-正构脂肪酮在安徽宣城红土堆积序列中表现出与黄土高原黄土古土壤序列相似的变化规律．其碳优势指数（CPI值）不仅能区分出黄色亚砂土和红色亚粘土（古土壤）,而且还能进一步体现出黄色土层和网纹红土层内部的旋回性变化。总的变化规律是,CPI值在古土壤层中表现出相对低值,如在宣城剖面古土壤层中变化于2．34．0之间;CPI值在宣城剖面黄土层中变化范围为2．47．1。成土作用增强,CPI值降低。α-正构脂肪酮这种规律性变化反映了成土过程中微生物对类脂物分子的改造强度,微生物不仅输入其本身的类脂物而且对高等植物不同类脂物（正构烷烃和脂肪酸）的改造都会使脂肪酮CPI值发生规律性变化。古土壤脂肪酮CPI值由此可以揭示受气候驱动的微生物作用,从而可以反映古气候的变化。     

木论喀斯特森林区生物多样性初报

本论喀斯特森林区位于广西环江毛南族自治县西北部。初步调查表明;（1）该林区属于中亚热带石灰岩常绿、落叶阔叶混交林生态系统,森林植被保存较好,面积为13 179．2公顷,森林覆盖率高达84％,这在世界同纬度地区实属罕见;（2）这次考察发现的成片单性木兰林是我国森林植被类型的新纪录、（3）该林区植物以亚热带成分占优势,热带成分次之,温带成分也有一定的比率,其区系主要为泛北极植物区中国-日本森林植物亚区滇黔桂地区的成分;（4）该林区有野生维管束植物537种,脊椎动物73种,昆虫410种,大型真菌69种,其中有国家级保护植物12种、动物19种,发现9个昆虫新种以及10种名贵的地下块菌。最后,本文阐述了该区生物多样性价值及保护现状,提出了进一步研究、保护和持续利用该区生物资源的合理化建议。     

苏州草鞋山遗址新石器时代以来的植硅石研究

本文首次对苏州草鞋山遗址新石器时代以来的植硅石进行分析。结果表明：马家浜文化时期气候发展经历了三个阶段。第一阶段（距今约６２７５ａ以前）气候温暖湿润,禾本科植物以芦竹亚科、竹亚科和水稻为主;第二阶段（距今约６２７５－６２００ａ间）气候温凉略干,黍亚科大量出现;第三阶段（距今约６２００－５９８５ａ间）气温回升。菘泽文化至宋代,气温继续变暖,此阶段,禾本科各亚科植物均有生长。本遗址马家浜文化时期发现典型水稻扇型及亚铃型硅酸体,反映该地自马家浜文化时期以来,水稻栽培已有一定规模     

浙江青浜岛现代植物群落和表土植硅体研究及环境意义

在植物分类基础上全面调查了浙江舟山青浜岛分布的植物群落类型,获得8个群丛类型,对青浜岛25种现代植物植硅体进行提取,共鉴定出17种形态类型。帽型、齿型、哑铃型、鞍型和扇型主要见于禾本科植物;蕨类主要产波状棒型和三棱柱型;木本主要产纺锤型和多边形板状型,这表明不同分类位置的植物产生不同的植硅体形态及组合。对横跨整个青浜岛东南—西北坡向的8个群丛样方进行表土植硅体提取分析,共获得14种植硅体形态类型,研究结果显示表土植硅体贡献主要来自禾本科、蕨类、阔叶类和裸子类植物。随着岛屿山体海拔的增加(海拔20—90m),示冷型和示干旱型植硅体增加,青浜岛局部生境(自东南向西北翻过山顶)气候变化表现为温暖湿润—温凉偏干—温暖湿润。表土植硅体组合灵敏地响应了海拔改变而引起的局地植被和环境的变化,是重建第四纪环境变化的可靠代用指标。     

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.