贺兰山油松和青海云杉交错区的物种丰富度研究

对贺兰山东坡的油松(Pinus tabulaeformisCarr.)和青海云杉(Picea crassifoliaKom.)交错区进行了野外群落调查和数据分析。结果表明,该交错区跨越2 100~2 500 m海拔范围,油松林和青海云杉林的海拔分界线为2 300~2 350 m。地形是该交错区群落物种丰富度的主要影响因子,阳坡群落的物种丰富度高于阴坡。中等坡度样地的物种丰富度较低;平缓或陡峭样地的物种丰富度较高。海拔升高,物种的丰富度也有所增加。当群落中油松和青海云杉的优势度基本相等时,为典型的油松与青海云杉交错区,在该交错区内,随着油松优势度的降低和青海云杉优势度的升高,土壤条件有所改善,物种丰富度增加。     

拉萨河流域亏组山植物物种丰富度和群落特征研究

为研究草地植物群落、物种丰富度及其分布格局与影响因子之间的关系,该文以拉萨河流域林周县卡孜乡亏组山为研究地点,对山体垂直样带(3900~5100 m)植物群落特征、植物物种丰富度与各影响因子之间的关系进行了研究。研究区域共设置了13个样带(每隔100 m设一个样带),每样带设置0.5 m×0.5 m的5个样方进行植被调查,运用主成分分析(PCA)和双向指示种分析法(TWINSPAN)对植物群落进行排序和分类,运用冗余分析法(RDA)对群落及其分布格局与影响因子之间的关系进行分析,对植物物种丰富度与各因子之间的关系进行了回归分析。结果表明:该山体植物可分为3个群落类型,含7个群丛;影响区域植物群落物种组成和分布格局的主要环境因子为海拔,其次是坡度;物种丰富度与海拔、分种盖度呈单峰关系,与总盖度、坡度、地上生物量呈正相关。该研究结果为区域植物物种多样性和山地植物资源的保护和可持续利用提供了科学依据。     

贺兰山甲虫物种丰富度分布格局及其环境解释

理解山地物种丰富度分布格局及其成因对于山地生物多样性保护具有重要意义。本文基于贺兰山地区甲虫31科252属469种的分布信息, 结合相关气候与生境异质性数据, 系统地探讨了贺兰山地区甲虫及6个优势科物种丰富度地理格局及其影响因素。结果表明, 甲虫物种丰富度及科属区系分化强度以贺兰山中段最高, 南段比北段高, 西坡比东坡高。基于183个栅格内物种分布的二元数据聚类分析, 贺兰山甲虫分布可分为北段强旱生景观甲虫地理群、中西段半湿生景观甲虫地理群、中东段及南段半旱生景观甲虫地理群3个地理群。冗余分析(RDA)表明年均温和年均降水量是影响最显著的因子。方差分解结果显示, 水分与能量因子共同解释了全部甲虫物种丰富度57.1%的空间变异, 单独解释率分别为5.9%和7.1%。生境异质性解释了全部甲虫物种丰富度35.2%的变异, 单独解释率仅为1.8%。气候因素与生境异质性对不同优势科物种丰富度的相对影响并不一致。在贺兰山的南段和北段, 生境异质性和水分因子对甲虫物种丰富度影响作用明显。水分和能量因子是贺兰山地区甲虫物种丰富度空间分布格局的主导因子, 生境异质性有助于提高甲虫物种丰富度。从未解释的比例来分析, 地形和土壤因素可能对贺兰山甲虫物种丰富度存在重要影响。     

地形对七姊妹山自然保护区植物丰富度及分布格局的影响

该研究以七姊妹山自然保护区40个(20×20m2)植物群落调查样方为基础,并采用回归分析和典型对应分析(CCA)的方法研究该区地形对植物物种丰富度及植物分布格局的影响,以明确海拔、坡度、坡向、坡位等地形因子的相对重要性,为该区植物多样性的保护和管理提供理论依据。结果表明:(1)七姊妹山自然保护区40个调查样地共有植物633种,隶属133科,316属,其中乔木118种,灌木150种,草本365种。(2)曲线回归方程拟合结果显示,七姊妹山自然保护区植物物种丰富度分别与海拔、坡度具有显著相关性,物种丰富度沿海拔梯度升高而增大,沿坡度梯度先减少后增大之后又减小。(3)从植物的生活型来看,在所有海拔段,乔木物种丰富度始终低于灌木和草本植物;在低、中低海拔地带,灌木物种丰富度均高于乔木和草本植物;而在中、高海拔地带草本植物物种丰富度较大且高于乔木和灌木。(4)CCA排序结果表明,地形因子对植物物种的分布具有显著影响按其影响强度排序为海拔坡度坡位坡向,说明海拔是影响该区植物物种分布最重要的地形因子。     

地形对贺兰山步甲群落物种多样性分布格局的影响

【目的】步甲是主要栖息于地表的种类最丰富的昆虫类群之一,它们对生境的变化更为敏感。分析地形因子对贺兰山步甲昆虫群落物种多样性分布格局的影响,以期揭示步甲昆虫物种多样性分布格局形成和稳定的机制。【方法】2015年7-8月选取贺兰山山地针叶林、山地疏林、山地灌丛、山地草原和浅山荒漠5种生境98个样地,用杯诱法对步甲群落物种组成和多样性进行调查,并采用典范对应分析(CCA)分析物种多样性指数和物种分布与地形因子之间的关系,运用广义可加模型(GAM)拟合不同生境步甲群落多样性指数对海拔梯度的响应曲线,探讨贺兰山步甲群落物种多样性的垂直分布格局。【结果】共采集步甲昆虫21属65种10 989头,其中,直角通缘步甲Pterostichus gebleri和径婪步甲Harpalus salinus为优势种,其个体数量分别占总捕获个体数的44.93%和11.33%。山地疏林生境步甲物种丰富度最高,山地针叶林的步甲Shannon-Wiener多样性指数最高,浅山荒漠的步甲均匀度最高。海拔、坡向、坡度、剖面曲率和地形湿度指数的综合作用对步甲物种多样性分布格局有显著影响。其中,海拔对5种生境的步甲分布影响均显著,且解释力度最高;坡向对山地针叶林和浅山荒漠步甲分布影响显著。步甲总体丰富度和个体数量与海拔呈不对称的单峰曲线关系,Shannon-Wiener多样性指数随海拔呈先递增后保持稳定的变化,均匀度指数与海拔呈"V"型变化趋势。【结论】贺兰山山地步甲物种多样性的分布格局受海拔为主的多种地形因子综合作用的影响。     

西双版纳种子植物物种多样性的垂直格局及机制

物种多样性海拔分布格局及其形成机制的研究是生物地理学和宏观生态学的重要议题之一。本文利用西双版纳植物专著资料, 结合高分辨率的地形和气候等数据, 探讨了面积、边界限制和现代气候对西双版纳野生种子植物物种丰富度及物种密度海拔分布格局的影响。结果表明: (1)物种丰富度呈单峰分布格局, 面积(81.9%)、边界限制(17.5%)和气候(60.0-69.3%)都不同程度地解释了物种丰富度的单峰格局; (2)利用幂函数种-面积关系计算的物种密度沿海拔大致呈减小的分布趋势, 气候的解释率降低为32.6-40.6%, 与边界限制无显著相关关系; (3)利用等面积高度带划分得到的物种密度沿海拔呈单峰变化趋势, 物种密度与边界限制无显著相关性, 但气候对物种密度的解释率为81.6-89.9%。研究结果有助于准确全面地理解物种多样性的海拔分布格局及其成因机制, 为西双版纳生物多样性保护提供理论支撑和实践指导。     

长江三峡库区物种多样性的垂直分布格局:气候、几何限制、面积及地形异质性的影响

为了验证生物多样性地理格局的几个重要假说,即种-面积关系、水分-能量动态假说、几何限制(中域效应)假说和生境异质性假说,作者以长江三峡库区维管植物物种丰富度沿海拔梯度的分布格局为例,采用多元回归和方差分解方法,研究了面积、气候、几何限制、地形异质性对多样性垂直格局的独立影响和协同作用,及其对各植物类群(不同分布宽度、不同分布区类型和不同生长型)影响的差异.结果表明,三峡库区各种植物类群的物种丰富度随着海拔上升均呈先升后降的单峰格局.水分-能量动态假说对多样性格局有很强的解释能力,其总的解释力(＞93％)明显高于其他所有解释机制.但对于很多植物类群而言,水分和能量的解释力中有很大一部分属于几何限制、面积及地形异质性等因素的协同作用.几何限制对分布宽度大的物种的多样性格局解释力很强,但对分布宽度小的物种作用很小;面积自身对物种丰富度解释力较强,但在考虑了其他环境因素的影响时,仅对少数植物类群有解释力;地形异质性自身对多样性的解释能力很弱,但在多元回归模型中起着必要的作用.综合来看,水分-能量动态是解释三峡库区植物多样性垂直格局的最重要的机制.几何限制的作用随着物种分布宽度减小而递减;地形异质性虽然对多样性垂直格局的影响较弱,但也是一种必要的补充解释机制;由于面积与气候、几何限制等因素存在强烈的共线性,面积对植物多样性垂直格局的相对作用大小还需要进一步的系统比较研究.     

黑河上游天然草地蝗虫物种丰富度与地形关系的GAM分析

地形差异性导致的环境异质性为小尺度范围内生物空间格局的形成与维持提供了一种重要机制, 是形成物种丰富度差异性的前提条件。借助GIS和S-PLUS软件, 利用广义可加模型(GAM)于7-8月对影响蝗虫分布的地形因子进行了研究, 在定量分析黑河上游祁连山区北坡地形的海拔分异特征的基础上研究了该区域蝗虫的丰富度与地形复杂度的关系。结果表明： 在36个样方中共采集蝗虫3 149头, 隶属于3科10属13种; 蝗虫丰富度受地形因子影响的顺序为海拔＞坡向＞坡度＞剖面曲率＞平面曲率＞坡位; 蝗虫的分布在平面曲率和剖面曲率各个梯度上的分布比较均衡, 在海拔、 坡向以及坡位的每个梯度上呈二次抛物线分布, 坡度上呈递减趋势; 从分布的区域上来看, 蝗虫在整个区域都有较高的丰富度, 但主要分布在海拔2 600~2 700 m区域, 坡向上则主要集中在西北坡和西坡, 与实际观测情况相一致。蝗虫丰富度与地形因子之间的相互关系以及分布状态, 反映了地形因子对水热条件的重分配使蝗虫分布格局出现多元化以及破碎化。     

香溪河流域河岸带植物群落物种丰富度格局

通过不同海拔高度的样带调查来研究香溪河流域河岸植物群落物种丰富度格局,并探讨河岸带中生物多样性维持的生态学机制。结果表明：河岸植物群落总的物种丰富度、乔木层物种丰富度和草本层物种丰富度沿海拔梯度均表现出相似的格局特征,利用抛物线方程进行拟合,物种丰富度与海拔之间有显著的相关性。灌木层物种丰富度和藤本植物物种丰富度格局特征不明显,且物种丰富度与坡度相关,在流域尺度上,海拔对物种丰富度有着重要的控制作用;在局部尺度上,季节性洪水干扰导致的空间异质性和小地形对群落的生物多样性有着重要的影响,研究结果支在于总的物种多样性在原始河流的中间河段将达到最大值的预测。     

广西猫儿山植物群落物种组成、群落结构及树种多样性的垂直分布格局

沿海拔梯度设置16个样地,对广西猫儿山植物群落物种多样性的垂直分布格局进行了初步研究。结果表明：(1)16个样地中共调查到乔木44科79属184种,其中常绿阔叶树121种、落叶阔叶树61种、针叶树2种;(2)随着海拔的上升,整个乔木层以及不同生活型的最大树高均呈显著下降趋势,而乔木树种的最大胸径、胸高断面积之和以及立木密度都呈现出先增大后减小的趋势;(3)物种丰富度在海拔1350m以下变化不明显,但1350m以上随着海拔的升高明显下降。在研究的海拔范围内,物种丰富度呈非常显著的单峰分布格局,最大的丰富度出现在中海拔群落中;(4)α多样性沿海拔梯度的变化趋势与物种丰富度相似,但没有后者显著。Shannon-Wiener指数(H’)和海拔之间有明显的负相关性,均匀度Pielou指数(E)在取样范围内并没有随着海拔梯度的变化表现出明显的规律;(5)1350m以下的相邻群落之间的Jaccard指数(CJ)大于1350m以上相邻群落之间的Jaccard指数,最小值出现在中海拔的植被过渡带。Cody指数也有类似的趋势,原因在于物种丰富度的变化;(6)在本研究的海拔范围内,海拔比坡度和坡向对群落的结构特征、物种丰富度以及α多样性的影响更大。而在局部尺度上,人为干扰以及小地形而导致的生境异质性对群落的物种多样性和结构特征有着重要的影响。     

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.