滇西北鼠疫自然疫源地齐氏姬鼠和大绒鼠对不同生境的选择

对仓山和洱海国家自然保护区4种年龄的森林以及周边的农田、果园、荒山灌丛和非保护区6种年龄的森林中齐氏姬鼠（Apodemus chevrieri）和大绒鼠（Eothenomys miletus）的种群数量进行了调查,研究了森林中2种小兽与栖境因子的关系以及人类活动对其种群数量的影响。结果表明,齐氏姬鼠和大绒鼠的生态位宽度分别为0．706和0．641,生态位重叠度为0．831。聚类分析显示：农田中2种小兽的种群数量最高;在非保护区森林、灌丛和果园,齐氏姬鼠和大绒鼠的数量显著低于农田,而高于保护区森林。人类干扰活动对森林底层植物有显著影响,能显著降低灌木的覆盖度、物种多度（除了6～10年生的森林）和密度,而增加草本植物的覆盖度和密度。回归结果表明,2种小兽的数量与森林草本植物的覆盖度呈正相关,而与灌木的密度呈负相关。     

森林演替对都江堰鼠类多样性的影响

为深入了解森林演替对野生动物群落结构和多样性格局的影响,于2012—2013年在四川省都江堰般若寺林场选择5种森林演替阶段(0~5、6~10、11~20、21~30 a和天然次生林(100 a),共计21个样地)对鼠类多样性进行调查。本次调查累计捕获鼠类9种,其中仓鼠科1种,鼠科8种。5种森林演替阶段共有物种有针毛鼠(Niviventer fulvescens)、中华姬鼠(Apodemus draco)、社鼠(N.confucianus)、高山姬鼠(A.chevrieri)和大耳姬鼠(A.latronum)。不同森林演替阶段之间的鼠类物种数、个体数和多样性特征差异不显著,但天然次生林中的鼠类个体数略高于其他演替阶段。多元统计分析(NMDS和CCA排序)表明,不同森林演替阶段的鼠类群落组成相似性较高,但灌木层和草本层盖度等生境因子可影响鼠种的分布。除高山姬鼠、针毛鼠和中华姬鼠等分布较广的种类外,其他种类对微生境有一定的选择倾向。小泡巨鼠(Leopoldamys edwardsi)主要生活于演替期长的天然次生林中,社鼠和大耳姬鼠主要分布在灌木层盖度较高的生境,巢鼠(Micromys minutus)和黑腹绒鼠(Eothenomys melanogaster)主要生活在草本层盖度较高的生境,大足鼠(Rattus nitidus)适于生活在草本层和灌木层盖度均适中的生境。综上所述,不同森林演替阶段之间的鼠类多样性差异较小,但森林演替所造成的微生境变化可能影响鼠类物种的分布和多样性格局。     

中国云南小兽寄生革螨的群落结构和空间分布

寄生在小兽体表的革螨可能是传播肾综合征出血热和立克次体痘等人兽共患病的媒介。本文报道了云南省28个县(市)小兽体表革螨的野外调查结果, 运用物种数、平均丰富度和Shannon多样性指数对小兽寄生革螨的群落特征和沿环境梯度的空间分布进行了研究, 并用系统聚类分析法 (SPSS 16.0软件)对18种主要小兽的革螨群落相似性进行了比较。在云南省28个县(市)共捕获到小兽14 544头, 隶属于5目（啮齿目、食虫目、攀鼩目、兔形目、食肉目）10科35属67种, 在捕获的小兽体表采集到革螨80 791头, 经鉴定属于10科33属112种。结果分析表明: 主要的宿主动物为黄胸鼠 Rattus tanezumi、齐氏姬鼠Apodemus chevrieri和大绒鼠Eothenomys miletus;纳氏厉螨Laelaps nuttalli、毒厉螨L. echidninus和贵州厉螨L. guizhouensis为革螨的优势种。齐氏姬鼠A. chevrieri、社鼠N. confucianus和黄胸鼠R. tanezumi体表寄生的革螨种类最多;臭鼩鼱Suncus murinus、齐氏姬鼠A. chevrieri和灰麝鼩Crocidura attenuata的革螨群落多样性最高。聚类分析结果表明, 大部分革螨群落的相似程度与相应小兽的亲缘关系及所处生态环境的相似性是基本一致的, 分类地位和生境选择相似的小兽, 它们的革螨群落也被聚为一类。革螨物种数沿纬度梯度的水平分布呈现两个峰值, 最大峰值出现在25°~26°N之间;沿海拔梯度的垂直分布呈单峰分布格局, 峰值在海拔2 000~2 500 m之间。革螨和小兽的多样性沿纬度梯度和海拔梯度的空间分布趋势也均表现出随着纬度和海拔的升高而先升高后降低的单峰型分布格局, 峰值分别出现在北纬25°~27°N和海拔2 000~2 500 m之间。结果提示云南革螨群落种类丰富, 多样性高。云南革螨物种数和多样性的分布格局可能直接受到古北和东洋两区系边缘效应的影响。     

人类活动对云南哀牢山小型兽类群落结构的影响

本文涉及云南景东哀牢山徐家坝森林地区,不同强度人类活动对小兽群落结构的影响,结果表明：1．在原生常绿阔叶林中小兽16种,数量9．81％,中华姬鼠和中华句胃为优势种：在原生林遭砍伐而演替为次生林内6种;数量1．18％;中华姬鼠和社鼠占优;在原生林遭严重破坏所形成的毛蕨草地上5种,数量0．92％,巢鼠为优势种,2．上述3种栖息地中小兽密度依次为每公顷36．05只,5．30只,和4．35只;生物量依次为每公顷917．18克,205．0克和107．75克,初步结论是：1．森林遭破坏后小兽群落组成,数量以及物种相对丰盛度均发生变化,2．物种多样性随森林破坏强度的加大而减少;3．森林破坏强度越大,小兽密度和生物量则越小。     

科尔沁沙地植被恢复系列上群落演替与物种多样性的恢复动态

通过对科尔沁沙地植被恢复系列上不同阶段的群落取样,研究了植被恢复过程中群落物种组成、物种多样性的变化过程.在演替时间分别为1年、3年、5年、12年、20年和30年的群落中,物种丰富度分别为7、11、17、14、28和30种,而物种多样性指数分别为1.458 8、2.610 0、3.108 4、1.696 8、3.738 6、3.639 6.在生活型结构上,一年生植物的种类数量占绝对优势,但随着演替进展,多年生植物的种类数量增加且单种植物的优势度超过了一年生植物,表明多年生植物在群落功能维持中占据重要地位.随演替进展,来自不同科属的植物增加.藜科植物在演替过程中种类数量较为稳定,特别是在演替早期藜科植物占有很高的优势度.禾本科种类随演替进展不断增加,且在群落中的优势度逐渐上升.总体上,随演替进展群落种类组成与物种多样性增加,群落生态优势度下降,而均匀度增加,群落趋向稳定.     

弃管杉木林杉木数量与群落物种多样性间的关系

森林群落物种多样性格局和动态一直是生态学的研究热点,人工林弃管后演替进程中物种多样性变化也很值得研究。杉木(Cunninghamia lanceolata)作为我国南方林区人工栽培最广、经济价值最高的用材树种之一,其人工林分布面积很大,通常群落结构简单、物种多样性低,然而群落中杉木数量如何影响植物物种多样性,迄今缺乏研究。在浙江省自然保护区内,选择不同疏伐强度和弃管时间的杉木人工林,建立了6个1 hm~2长期动态监测样地,在10 m×10 m、20 m×20 m、50 m×50 m和100 m×100 m尺度下,探究群落物种多样性(物种丰富度、Simpson指数、Shannon-Wiener指数和Pielou均匀度指数)的变化规律,分析杉木数量(多度和相对多度)对物种多样性的影响。结果显示：弃管前对杉木林的疏伐强度越高,演替恢复后的群落物种多样性越高。相同疏伐程度下,物种多样性随演替时间的延长有先升高后降低的趋势。取样尺度小于100 m×100 m时,杉木数量与物种多样性呈极显著负相关;100 m×100 m尺度下仅杉木相对多度与3种多样性指数呈显著负相关,杉木多度与各物种多样性均无显...     

云南苍山火烧迹地不同恢复期地表蜘蛛群落多样性

为了解云南苍山针阔混交林火烧迹地恢复过程地表蜘蛛群落多样性变化,于2009年1月份-2009年12月份,运用陷阱法,以“空间序列代替时间序列”,调查了苍山森林火干扰后不同恢复期样地(火干扰后2、10、18、23、33a和对照样地)地表蜘蛛多样性.研究结果表明,(1)物种组成及相对多度:不同恢复期随着恢复时间的增加优势类群更替趋势明显;(2)多样性:恢复1Oa样地地表蜘蛛群落多度显著大于其他恢复期(P＜0.05),而不同恢复期地表蜘蛛物种多样性却没有显著差异;(3)群落相似性:PCoA相似性分析将地表蜘蛛群落发展过程划分为火烧后2a、火烧后10a和火烧后18-33a 3个阶段;(4)指示物种:西菱头蛛Sibianor sp.1等是阶段1的指示物种,格氏狼蛛Lycosa grahami等是阶段2的指示物种,花蟹蛛Xysticus sp.2等是阶段3的指示物种,弱蛛Leptoneta sp.1等是对照的指示物种.火干扰改变了苍山针阔混交林原有的地表蜘蛛群落多样性;指示物种对生境的选择能够反映出不同恢复阶段地表环境变化;5个不同恢复时期火烧迹地中恢复最久的火烧迹地地表蜘蛛群落仍没有完成恢复,说明云南苍山火迹地地表蜘蛛的恢复需要30a以上.     

四川南充市郊区鼠型小兽群落组成研究

2005年3月～2006年2月对四川省南充市郊区的鼠型小兽进行了调查。共捕获鼠型小兽1499只,隶属于2目2科7种,根据优势种分为两个群落:微尾鼩 黑线姬鼠群落中除优势种外,还捕到少量大足鼠、社鼠、褐家鼠和灰麝鼩,主要分布于住宅区以外的农田林地;褐家鼠 黄胸鼠群落,有少量微尾鼩,分布于住宅区。采用Shannon-Weiner多样性指数、均匀性指数、Hurlbert生态优势度和物种数对沟谷地、半坡地、坡顶地以及住宅区4种微生境中捕获的小兽进行了分析。住宅区的多样性指数、均匀性指数最高,其次为沟谷地。     

公路碾压干扰下群落植物多样性——以藏北矮嵩草草甸为例

运用时空替换法,以空间变换替代时间变换,对公路碾压干扰下藏北矮嵩草草甸恢复演替中不同阶段群落植物多样性进行研究.结果表明：各草地群落样方中共出现高等植物33种,其中菊、豆、禾本科和蔷薇科合计16种,占48.48﹪,在其自然恢复演替所起的作用最大;莎草科植物作为顶级群落的建群种具有重要作用.物种构成具有明显的阶段性特征：演替前期以1年生和2年生植物为主;中期多年生草本植物逐渐占据优势;后期矮嵩草成为单优势种;菊叶萎陵菜和二裂萎陵菜几乎贯穿始终.物种积聚主要是在演替前期和中期完成,其积聚过程符合二次曲线.演替后期群落植物多样性程度最高,多样性随演替进程表现为逻辑斯谛增长规律：前期群落物种丰富度较低,均匀度较高,生态优势度？也比较高,但综合多样性较低;中期群落的均匀度下降,生态优势度也同时下降,综合多样性高;后期矮嵩草成为群落的单优势种,群落的均匀度和生态优势度均下降,综合多样性仍然增加.     

半湿润常绿阔叶林次生演替阶段植物多样性和群落结构特征

以飒马场不同次生演潜阶段的半湿润常绿阔叶林为对象,测定物种丰富度、群落数量特征指标,分析植物多样性与群落结构特征之间的关系.结果表明,随着植物群落演替,物种丰富度不断增加,物种丰富度最高演替阶段的乔木层物种达到24个;植物多样性与植物个体密度间呈正相关关系;乔木层植物个体平均高与植物多样性间呈负相关关系;群落郁闭度和胸高断面积与植物多样性之间则呈对数函数关系.植物多样性与优势种个体密度和群落地上部分现存量间未呈现一致性规律.植物种-个体数间呈幂函数关系.随着植物多样性增加,种间竞争加剧.每个植物种为了维持临界最低种群,可能采取最大种群策略,导致群落植物个体数增加,密度增大,从而改变了群落结构特征.     

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.