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。     

6种人工针叶幼林下地表苔藓植物层片的物种多样性与结构特征

 为了评估人工林苔藓植物发育状况,同时为人工林生态功能评价提供依据,采用样地取样方法,调查分析了岷江上游大沟流域6种人工幼龄针叶林（川西云杉(Picea balfouriana)林、日本落叶松(Larix kaempferi)林、油松(Pinus tabulaeformis)林、华山松(Pinus armandii)林、油松-华山松混交林和川西云杉-华山松混交林）林下地表苔藓植物层片物种组成、多样性以及结构特征及其异同。6种人工林下共发现了19种苔藓,各林下组成数量在7～13种。除云杉林外,纯林下苔藓种数均小于或者等于混交林下;6种人工林下地表苔藓植物平均盖度、平均密度、平均厚度分别在0.41%±1.49%～17.79%±1.67%、(27.99±367.95)～(3 807.11±412.90)株•m-2和(1.80±1.51)～(19.89±1.69) mm之间。无论是多样性指数,还是结构参数,均以川西云杉林最高,而华山松林最低。总体说来,岷江上游人工针叶幼林下地表苔藓组成物种较少、物种多样性指数（物种丰富度指数、Shannon-Wiener指数）低、Simpson指数高、结构参数（密度、盖度、厚度）较小,说明林下地表苔藓植物组成单一、结构相当简单,发育不良。综合分析表明,具有相对较低林冠郁闭度与林木密度的云杉林是6类人工林中恢复状况相对最好的类型,暗示出疏伐、修枝等管理措施可促进人工密林下地表苔藓植物生物多样性以及地表苔藓植物层片结构的改善。     

北京东灵山主要森林植被中苔藓植物的物种多样性

通过对北京东灵山地区32个样地植被及苔藓植物的调查,对主要森林植被中苔藓植物物种多样性进行分析。结果表明:东灵山主要森林植被中共有苔藓植物16科33属79种,优势科为青藓科(Brachytheciaceae)和绢藓科(Entodontaceae)等。密叶绢藓(Entodoncompressus)、小牛舌藓(Anomodon minor)等为优势种。地面生苔藓植物物种丰富度以落叶阔叶混交林中最大,白桦林中最小,苔藓植物群落相似性以辽东栎林与落叶阔叶林之间最高,以山杨林与油松林之间最低。树附生苔藓植物物种丰富度以落叶阔叶混交林中最大,油松林中最小;苔藓植物群落相似性以油松林和山杨林之间最高,华北落叶松林与白桦林之间最低。地面生和树附生苔藓植物多样性与林型、树种及其所形成的林内微环境相关。     

内蒙古准格尔黄土丘陵区不同植被类型地面生苔藓植物物种多样性研究

在野外样方调查的基础上研究了准格尔黄土丘陵沟壑区9种不同植被类型地面生苔藓植物物种多样性及其与环境因子之间的相关性:(1)共发现苔藓植物8科18属35种,以丛藓科(Pottiaceae)和真藓科(Bryaceae)为优势科,优势种有真藓(Bryum argenteu)、双色真藓(Bryum bicolor)、土生对齿藓(Didymodon vinealis)、褶叶青藓(Brachythecium salebrosum)、灰藓凹叶变种(Hypnum cupressiforme var.lacunosum)等10种;(2)Alpha多样性指数中,Patrick丰富度指数在4~21种,Shannon-Wiener指数和Simpson多样性指数分别在1.078 0~2.153 3和0.588 9~0.826 3,天然植被变化规律为杜松林(Juniperus rigida forest)茭蒿群落(Artemisia giraldii shrub)山桃林(Prunu davidiana forest)锦鸡儿群落(Caragana intermedia shrub)本氏针茅群落(Stipa bungeana steppe)百里香群落(Thymus serpyllum steppe),而人工杨树林(Populus simonii forest)、侧柏林(Platycladus orientalis forest)与锦鸡儿灌丛以及人工油松林(Pinus tabulaeformis forest)与杜松林上述3个指数相近;(3)影响物种多样性的主要环境因子有土壤水分、空气湿度和光照强度;(4)Bata多样性指数在0.240 0~0.857 1,本氏针茅群落与人工杨树林物种相似性最大,百里香群落与杜松林物种相似性最小,群落之间物种组成相似性和差异性能够揭示各样地生境差异性和相似性。杜松林下的苔藓植物物种多样性为最高,是该地区地面生苔藓植物物种多样性保护的主要地区。     

重庆主城区住宅小区苔藓组成与多样性

目前对于人造生活环境中的苔藓植物组成与多样性所知甚少。本文报道了城市住宅小区中的苔藓植物多样性, 以丰富重庆市苔藓植物区系资料, 为小区环境质量评估提供依据, 为认识苔藓植物对新环境的适应能力提供科学基础。通过对重庆主城九区23个住宅小区进行详细调查, 报道苔藓植物19科33属84种。种类组成以土生的丛藓科和真藓科为主。常见种类包括小凤尾藓(Fissidens bryoides)、大叶石灰藓(Hydrogonium majusculum)、细叶小羽藓(Haplocladium microphyllum)、鳞叶藓(Taxiphyllum taxirameum)和绿片苔(Aneura pinguis)共5种。各住宅小区苔藓物种数介于5-25种之间。物种相似性程度非常低, 群落间差异较为显著, 多样性较高。苔藓生活型以丛集型为主。典范对应分析排序结果显示, 住宅小区居住户数对其苔藓物种多样性影响最大, 其次是绿地面积。研究结果表明, 住宅小区是城市苔藓植物的重要分布区域之一。地理环境差异、城市化水平、小区内部小生境条件和人为干扰程度可能是造成各住宅小区苔藓组成差异的原因。     

喀斯特山地高校苔藓植物多样性及环境响应——以贵州大学为例

以贵州大学喀斯特山地校园为对象,调查其苔藓植物物种多样性及其生境特征,探讨苔藓植物生长与环境的关系。结果表明,研究区域内苔藓植物共12科27属51种。优势科是丛藓科(Pottiaceae)、青藓科(Brachytheciaceae)和灰藓科(Hypnaceae);主要生活型为丛集型、交织型和垫型;不同功能区域的苔藓植物生物多样性从高到低依次为行政办公区、休闲游憩区、教学科研区、体育运动区、宿舍休息区;不同生境物种丰富度从高到低依次是疏林草坪、林下、草坪环境、灌丛花池、道路;人为干扰程度与光照、湿度是影响苔藓植物多样性组成的重要因子。研究区域内苔藓植物多样性较低,多为土生藓类。在苔藓生长的微生境中,人为干扰低、空气湿度大的林地、疏林草坪更利于苔藓生长。     

不同生境对藏东南地面生苔藓多样性和生物量的影响

为解析苔藓在藏东南森林生态系统中的重要生态作用, 以及森林干扰对林内地面生苔藓的影响, 该研究以藏东南色季拉山地面生苔藓植物为调查对象, 选取林分、坡向、坡度和地势组成等相似的7块100 m × 100 m的样地, 每块样地以林窗为中心, 在其东、南、西、北4个方向选取林窗、林缘和林下3种不同生境设置50 cm × 50 cm的样方, 每块样地共12个样方, 共计168个样方。通过对每个样方进行苔藓植物调查采集, 研究了西藏色季拉山苔藓多样性和不同生境条件下地面生苔藓单位面积生物量特征。主要结果: (1)研究区共有苔藓植物24科63属110种。其中, 优势科有8个, 分别是丛藓科、曲尾藓科、金发藓科、提灯藓科、真藓科、紫萼藓科、青藓科和灰藓科。苔藓各科分布规律明显, 曲尾藓科和真藓科广泛分布于各个海拔, 金发藓科、真藓科和提灯藓科分布在海拔3 700-4 300 m, 而丛藓科多分布在4 300 m以上。(2)林窗生境较林缘和林下复杂, 它干扰了苔藓物种组成和群落结构, 其苔藓种类最多、结构最复杂, 而林下的苔藓种类最少, 群落结构最简单。林窗地面生苔藓生物量最高, 其次为林缘, 林下苔藓生物量最低。(3)地面生苔藓生物量大小不仅受其物种组成、盖度、体形和群落结构的影响, 而且是众多因子共同作用的结果, 而非某一因子起主导作用。     

浙江西天目山30年来苔藓物种多样性变化

苔藓物种多样性变化对苔藓植物保护和森林生态系统健康起着重要的预警作用.基于1977-1980年和2010-2011年对西天目山国家自然保护区苔藓植物的两次详细调查,本文比较了该地区1977-2011年间苔藓植物物种多样性的变化.结果表明:(1)在过去的30年间,该地区苔藓植物的科、属、种数均呈下降趋势,苔类植物的属、种数减少尤为显著;(2)青藓科、曲尾藓科、灰藓科和丛藓科一直为该地区的优势科;(3)科的稳定性均高于属、种;(4)缓冲区的总物种数变化最大,新增物种数最多;核心区(进山门-老殿)苔藓植物种类始终最为丰富,两个时期的物种相似性最高,且苔类占新增物种数百分比最高;核心区(老殿-仙人顶)苔藓物种数最少,相似性最低;(5)核心区的物种多样性要高于缓冲区,是该地区保护苔藓植物多样性的关键区域.     

哀牢山湿性常绿阔叶林树干4种附生苔藓植物的水分变化对光合、荧光参数的影响

以云南哀牢山湿性常绿阔叶林中的附生苔藓植物为对象,研究林内4种树干附生苔藓植物阿萨羽苔(Plagiochila assamica Steph.)、西南树平藓(Homaliodendron montagneanum(Müll.Hal.)M.Fleisch.)、刀叶树平藓(H.scalpellifolium(Mitt.)M.Fleisch.)、大羽藓(Thuidium cymbifolium(Dozy et Molk.)Dozy et Molk.)的吸水力、失水特征和脱水耐性,稳定碳同位素(δ~(13)C)值,以及水分变化对苔藓净光合速率和荧光参数的影响。结果显示:(1)4种附生苔藓植物均具有较强的吸水能力和较低持水力,脱水耐性较强,脱水后均可迅速复水;(2)4种附生苔藓植物的δ~(13)C值较低,其水分利用效率小于其他维管束植物;除大羽藓外,其余3种附生苔藓雨季的δ~(13)C值与水分利用效率均高于干季;(3)4种附生苔藓植物的净光合速率(Pn)随着含水量的降低而降低,在含水量小于60%~80%时,其最大光化学效率(Fv/Fm)急剧下降,反映出这些附生苔藓植物的光合、荧光特性对水分变化非常敏感。     

百里杜鹃国家森林公园苔藓植物分布及对环境因子关系研究

为了研究百里杜鹃国家森林公园苔藓植物的物种多样性, 对该公园中5 种典型植物配置杜鹃林苔藓植物进行调查, 计测了50 个样方中的苔藓植物。结果表明: 共采集到地面生苔藓植物16 科, 25 属, 47 种, 进行物种多样性比较,苔藓植物的Shannon-Wiener 和种间相遇机率指数较低, Simpson 指数则较高, 说明各种杜鹃林下总的物种丰富度均较低。优势度集中在少数种类如黄牛毛藓Ditrichum pallidum、曲尾藓Dwranum scoparium、葫芦藓Funaria hygrometrica、大灰藓Hypnum plumaeforme 等物种上; 采用典范对应分析CCA (Canonical Correlation Analysis)对5 个样24 种主要优势苔藓植物与环境因子间关系进行分析, 发现人为干扰度是影响苔藓植物分布和物种丰富度的主要影响因子, 其他影响因子依次为林木郁闭度、林木密度、海拔高度、坡位、坡度和坡向。     

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.