长白山暗针叶林苔藓植物生物量的研究

在长白山北坡暗针叶林对地面和树附生苔藓植物的生物量进行了测定．地面生苔藓采取样带调查取样法测定,树附生苔藓应用McCune方法对树干和树枝的附生苔藓生物量都做了细致的测定．结果表明,长白山暗针叶林中的苔藓植物分布很不均匀,随海拔变化差异很大,海拔1100m最低,仅为543kg·hm^-2;海拔1250m最高,达5097kg·hm^-2．苔藓植物生物量的变化对生境有很好的指示作用,特别是塔藓和拟垂枝藓的生物量随海拔的变化与森林系统的群落学特点有一定的相关性：在海拔1100～1700m,塔藓的生物量与臭冷杉的重要值变化趋势相近,随海拔升高而减少;拟垂枝藓的生物量与鱼鳞云杉重要值的变化趋势相似,随海拔升高而增加．此外,生物量随海拔的变化表明了不同苔藓植物对环境条件要求的差异,拟垂枝藓比塔藓水分条件要求更高．因此,生物量的研究在植物生理上也有一定的指示作用．     

长白山暗针叶林苔藓植物对三种针叶树种子萌发及幼苗生长的影响

研究了长白山暗针叶林两种主要地面苔藓植物——塔藓和拟垂枝藓对红松、红皮云杉和落叶松种子萌发及幼苗生长的影响.结果表明,在一定浓度下,塔藓浸提液抑制红松发芽,拟垂枝藓浸提液促进红松发芽;苔藓浸提液对红皮云杉和落叶松的发芽率没有显著影响,但不同程度地加快了种子日萌发高峰的出现.用苔藓植物体直接培养红皮云杉和落叶松种子,发现活植物体量大时对发芽率没有显著影响,但延迟了红皮云杉种子萌发高峰的出现,加速了落叶松种子萌发高峰的出现;杀青后的苔藓植物体则明显地抑制种子发芽.通过幼苗培养实验,发现苔藓植物浸提液抑制红皮云杉和红松幼苗生长,但促进了落叶松幼苗的生长;不同处理的苔藓植物体对幼苗生长的影响差异较大,活植物体量大时,两种苔藓均促进了红皮云杉和落叶松幼苗生长,而杀青后植物体则明显地抑制幼苗生长.     

长白山森林生态系统腐木生苔藓植物生态分布的DCA排序研究

应用除趋势对应分析（ＤＣＡ）对长白山不同森林类型腐木生苔藓植物分布研究表明,长白山红松阔叶混交林、暗针叶林以及两者之间的过渡林林下腐木生苔藓植物组成明显不同．红松阔叶混交林以尖叶匍灯藓、毛尖羽藓、细枝青藓等为主;过渡林以尖叶匍灯藓、鞭枝疣灯藓、羽藓、腐木藓、塔藓等为主;暗针叶林的以塔藓、钩枝镰刀藓、拟垂枝藓、曲背藓、毛梳藓等为主．暗针叶林林下腐木生苔藓植物发生量最大,物种的多样性也最高．海拔高度和林冠郁闭度是影响长白山森林林下腐木生苔藓植物生态分布的主要因素．     

边缘效应对山地湿性常绿阔叶林附生植物的影响

作为热带、亚热带地区森林生态系统中重要组成成分之一的附生植物,对环境变化尤为敏感。为了解附生植物对森林生境破碎化的响应,本研究选择哀牢山北段徐家坝山地湿性常绿阔叶林因人为干扰而形成的四处森林边缘为研究对象,分别在距离林缘10、20、40和80m的位置设立样带,采用树干取样法调查各样带内距地面0-2m范围附生植物的物种组成、生物量和附生苔藓植物的生活型特征。结果显示：边缘效应对单位面积附生植物的生物量和附生苔藓植物盖度均具有极显著的影响（P〈0．001）,其中附生苔藓比附生蕨类对边缘效应更为敏感。边缘效应对附生苔藓植物的作用强度在各生活型之间存在着差异,其中对丛集型（P=0．014）和交织型（P=0．030）的附生苔藓植物的影响最显著。综合附生植物在各样带的分布特征,我们认为单位面积上附生植物的生物量和附生苔藓植物的盖度可作为指示森林边缘生境的重要指标。黄牛毛藓（Ditrichum pallidum）、角状刺枝藓（Wijkia hornschuchi）和格氏剪叶苔（Herbertus giraldianus）的分布具有指示林缘生境的意义,而尖叶羽藓（Thuidium philibertii）、大羽藓（zcymbifolium）、多疣麻羽藓（Claopodium pellucinerve）、波叶金枝藓（Pseudotrismegistia undulata）和扭叶藓（Trachypus bicolor）的分布局限于林内,具有一定的保护价值。     

长白山暗针叶林苔藓植物在养分循环中的作用

测定了长白山暗针叶林5种主要苔藓植物养分含量,并结合生物量的测定结果,推算单位面积的苔藓植物养分含量.结果表明,单位面积苔藓植物氮含量为5.371 kg·hm^-2,是乔、灌、草总氮量的12.22%;钾含量为12.02 kg·hm^-2,是乔、灌、草总钾量的5.63%;磷含量为31.679 kg·hm^-2,是乔、灌、草总磷量的70.57%,超过了乔木磷含量,是草本植物磷含量的2.倍、灌木磷含量的792倍,苔藓植物是暗针叶林重要的磷库.同时测定不同苔藓盖度下土壤中的养分含量.方差分析结果显示,不同苔藓盖度下土壤中氮、钾含量差别不大,磷含量差异显著,没有苔藓覆盖的土壤中磷含量最高,为0.19±0.023 g·kg^-1;苔藓盖度为第6级(80%～100%),土壤中磷含量最低,为0.36±0.017 g·kg^-1,随苔藓盖度的增加土壤中磷含量有减少的趋势.     

云南树干附生苔藓生物量沿纬度及海拔梯度的变化特征

为探讨不同森林群落树干附生苔藓的生物量及其组成沿纬度、海拔梯度的变化格局,采用样地调查法,对云南热带(勐腊县)、亚热带(镇沅县)及亚高山(丽江玉龙县)不同海拔不同森林类型中树干附生苔藓的总生物量、优势组分生物量和不同生活型组分生物量的分布格局进行调查研究。结果表明:(1)随着纬度、海拔的升高,3种代表性森林类型单位面积树干附生苔藓植物的生物量上升,以丽江亚高山针叶林最高(3.57 g·400 cm~(-2));镇沅亚热带常绿阔叶林次之,为2.00 g·400 cm~(-2);勐腊热带森林最低,仅为0.53 g·400 cm~(-2)。(2)3种森林类型树干附生苔藓植物的优势组分中无相同物种。(3)随着纬度、海拔的上升,单位面积附生苔藓植物平均生物量上升,优势种类的相对生物量占比有所下降,勐腊热带森林、镇沅哀牢山亚热带常绿阔叶林和丽江玉龙雪山亚高山针叶林树干附生苔藓优势组分的生物量分别占总生物量的92.3%、75.6%和85.2%。(4)随着纬度和海拔的上升,3种森林类型树干附生苔藓植物群落不同生活型组分的生物量存在明显的分异规律。细平铺型、扇形和丛集型分别为勐腊热带森林、镇沅哀牢山亚热带常绿阔叶林和丽江玉龙雪山亚高山针叶林的优势附生苔藓生活型。     

长白山地区森林生态系统树附生苔藓植物群落分布格局研究

 以苔藓植物盖度为指标,应用双向指示种分析(TWINSPAN)和除趋势对应分析(DCA)对长白山地区不同森林类型36个样地的树附生苔藓植物群落分布格局进行了研究。结果表明,长白山地区树附生苔藓植物的分布格局与森林植被类型相对应,可分成落叶松林、岳桦林、暗针叶林、暗针叶林与红松阔叶林间过渡林、红松阔叶林、白桦林6类树附生苔藓植物群落类型,文章分析了影响树附生苔藓植物群落生态分布的环境因素。     

西藏色季拉山暗针叶林苔藓多样性及林窗干扰的影响

为了解西藏色季拉山暗针叶林苔藓多样性及林窗干扰的影响,在过去工作积累的基础上研究了色季拉山西坡5块样地内不同林内环境(林窗、林缘和林下)地面、腐木和树附生苔藓生物量特征。结果表明, 地面生单位面积苔藓植物生物量储量最高,平均910.10 g/m²,其次为腐木生(221.90 g/m²),树附生的最低(53.59 g/m²)。林窗地面生苔藓单位面积生物量最高,均值为360.47 g/m²,其次为林下(305.51 g/m²),最小为林缘(244.11 g/m²);林窗、林缘和林下间的地面生苔藓单位面积生物量差异显著(P＜0.05)。沿海拔梯度,林窗苔藓单位面积生物量表现出先增加后减少的趋势。因此,在西藏色季拉山暗针叶林内,林窗对地面生苔藓单位面积生物量有显著影响。     

UV－B辐射增强对长白山五种藓类植物生长的影响

对生长在中国长白山的5种藓类植物——垂枝藓、拟垂枝藓、塔藓、星塔藓和高山金发藓分别以辐射强度为0.2(自然光照,对照)、3.0(紫外线中等辐射强度)和6.0kJ.m-2.d-1(高剂量辐射强度)的UV-B照射40d后,测定其株高、生物量及叶绿素含量.结果表明:中等和高强度的UV-B辐射使拟垂枝藓和塔藓的株高、生物量和叶绿素含量分别下降了32.3%、62.4%、81.3%和21.4%、59.4%、62.8%,其相对生长速率均为负值;高剂量UV-B辐射处理下垂枝藓的生物量稍有上升,而高山金发藓地下部分的生物量增加1倍,但叶绿素含量变化不明显.高山金发藓和垂枝藓抵抗UV-B辐射的能力较强,拟垂枝藓和塔藓对UV-B辐射较敏感.     

小秦岭自然保护区苔藓植物群落数量分类、排序及多样性垂直格局

苔藓物种多样性沿海拔梯度呈什么样的分布格局?基于53个20 m×20 m样地,采集并鉴定了样地内所有生境中的苔藓物种;采用多元回归树(multivariate regression trees,MRT)对苔藓植物进行分类;采用典范对应分析(canonical correspondence analysis,CCA)进行排序分析;用广义线性模型(Generalized Linear Model,GLM)研究苔藓物种多样性沿海拔的分布格局。结果如下:(1)采集的1378份苔藓植物标本经过鉴定,共有33科89属240种,其中藓类226种,苔类14种;(2)经交叉验证认为本区苔藓植物可分为4类,Ⅰ长肋青藓(Brachythecium populeum)+大叶匐灯藓(Plagiomnium succulentum)+圆叶匐灯藓(Plagiomnium vesicatum)群落,Ⅱ灰白青藓(Brachythecium albicans)+宽叶青藓(Brachythecium curtum)+短肋羽藓(Thuidium kanedae)+平肋提灯藓(Mnium laevinerve)群落,Ⅲ短肋羽藓(Thuidium kanedae)+光萼叶苔(Jungermannia leiantha)+薄罗藓(Leskea polycarpa)+叉肋藓(Trachyphyllum inflexum)群落,Ⅳ宽叶青藓(Brachythecium curtum)+垂蒴棉藓(Plagiothecium nemorale)+全缘匐灯藓(Plagiomnium integrum)群落;(3)海拔、坡度和坡向对苔藓物种分布的解释量为7.29%;(4)苔藓物种多样性随海拔的变化成明显的上升格局。通过研究了解了小秦岭国家级自然保护区苔藓物种组成、群丛划分以及每种苔藓植物的海拔分布范围;苔藓物种多样性随海拔的上升呈显著的上升格局,与乔木、灌木和草本的分布格局不同。希望此研究能为苔藓植物生态学研究和物种多样性保护提供参考。     

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.