贡嘎山东坡典型植被类型土壤动物群落特征

为了掌握贡嘎山垂直植被带间土壤动物群落结构及多样性,2012年5月至10月间对贡嘎山东坡的常绿阔叶林、落叶阔叶林、针阔混交林和暗针叶林4种典型植被土壤动物群落进行了调查。共捕获土壤动物347只,隶属于10纲29目68类,其中山蛩属(Spirobolus)为优势类群。土壤动物的群落密度、生物量以及多样性呈常绿阔叶林落叶阔叶林针阔混交林暗针叶林趋势,其中密度、类群丰富度和Shannon-Wiener指数的变化具有显著差异(P0.05);落叶阔叶林和针阔混交林间的土壤动物群落结构差异明显,其他植被类型间的差异性受季节影响。从各功能群结构来看,腐食性和杂食性土壤动物占主要地位;各功能群的生物量均以常绿阔叶林和落叶阔叶林较高,针阔混交林和暗针叶林较低,而相对生物量的变化趋势各不相同,仅有腐食性功能群的生物量及植食性功能群的相对生物量在各垂直植被带间有显著差异(P0.05)。群落密度、生物量、类群丰富度、Shannon-Wiener指数以及腐食性和捕食性功能群的生物量与土壤温度呈显著相关(P0.05)。研究结果表明:贡嘎山东坡土壤动物的群落组成、多样性及功能群结构在各典型植被类型间有明显差异,土壤温度是影响土壤动物垂直分布格局的主要环境因子。     

森林演替过程中优势树种凋落叶对土壤微生物组成的影响

为了进一步认识森林群落演替机理,研究了黄土高原马栏林区处于不同演替阶段的森林土壤微生物组成,以及优势树种凋落叶对土壤微生物组成的影响.采用凋落叶浸提液处理不同类型的土壤,利用土壤浸提液固体培养基测定微生物数量,以系统聚类和主成分分析等方法进行数据分析.结果表明:微生物总数量及土壤细菌数量按白桦(Betulaplatyphylla)林→油松(Pinus tabulaeformis)林→辽东栎(Quercus liaotungensis)林递增;在先锋森林群落向顶极群落演替过程中,微生物组成的综合性指标Shannon-Wiener指数呈下降趋势;土壤微生物3大类群中,数量较少者对Shannon-Wiener指数的大小变化起着较大作用;依据可培养微生物组成,8种土样可划分为3个类群,辽东栎及油松凋落叶对土壤微生物组成的影响不同,辽东栎凋落叶对土壤微生物学性质的作用更强;马栏林区森林土壤微生物组成与植被类型及演替阶段关系密切;演替高级阶段森林优势树种凋落叶可能通过其对土壤微生物组成的改造优势,逐渐改变土壤的微生物学性质,进而促进植被演替.     

鼎湖山不同自然植被土壤动物群落结构时空变化

2001年10月~2002年8月采用大型改良干漏斗和手拣法对鼎湖山鼎湖山南亚热带典型常绿阔叶林、河岸常绿阔叶林、山地常绿阔叶林、针阔混交林、沟谷常绿阔叶林和灌木草丛6种自然植被类型土壤动物群落结构时空变化进行初步调查。结果表明,蜱螨目(A carina)和弹尾目(Co llem bo la)为6种自然植被常年优势类群,缨翅目(T hysanoptera)、鞘翅目(Co leoptera)、膜翅目(Hym enoptera)和双翅目(D iptera)幼虫则为常年常见类群。土壤动物群落类群和个体数量的消长规律分别是:10月=6月=8月>4月>2月=12月和4月>10月>6月>8月>2月>12月。土壤动物个体数量总数依次为南亚热带典型常绿阔叶林>河岸常绿阔叶林>山地常绿阔叶林>沟谷常绿阔叶林>针阔混交林>灌木草丛;不同月份、不同植被类型以及不同月份和不同植被类型之间土壤动物群落的组成具有较大变化,组成差异极显著(F=5.63,α=0.0001;F=11.08,α=0.0001;F=2.97,α=0.0001),不同类群之间个体数量差异极显著(F=102.38,α=0.0001),但月份间类群数差异不显著(F=0.50,α>0.05)。多样性分析表明,类群多样性和均匀性指数除南亚热带典型常绿阔叶林、山地常绿阔叶林12月最高外,其它则2月最高,优势度指数则相反;山地常绿阔叶林土壤动物群落多样性指数和均匀性指数最大,针阔混交林则最小。     

黄土高原马栏林区主要森林群落物种多样性研究

应用丰富度指数(S)、多样性指数(H1)、优势度指数(D)和均匀度指数(Js)对子午岭马栏林区的主要森林群落物种多样性进行了研究。结果表明:41个样地共记录草本151种,灌木111种,乔木33种。马栏林区森林植物群落其总体多样性是混交林>纯林>人工林;不同森林群落各层的物种多样性基本都表现为灌木层>草本层>乔木层;物种多样性乔木层以油松(Pinus tabulaeformis) 辽东栎(Quercus liaotungensis)混交林和落叶阔叶混交林较高,灌木层以油松 白桦(Betula platyphylla)混交林、白桦林和天然油松林多样性较高;草本层则是人工刺槐 (Robinia pseudoacacia)林、白桦林和山杨(Populus davidiana)林多样性较高。人工刺槐林和人工油松林在乔木层和灌木层多样性指数都较低。物种均匀度乔木层是落叶阔叶混交林最高,人工油松林和人工刺槐林最低;灌木层各群落的均匀度较为接近;草本层则表现为人工刺槐林均匀度最高,混交林最低。β多样性分析显示人工刺槐林与其它森林群落相异性较大,而辽东栎林、天然油松林和油松 白桦混交林均与油松 辽东栎混交林的相异性较小。研究表明多树种营造混交林可以增加群落的多样性,建造具有较高物种多样性的群落应种植混交林取代单一物种的人工纯林,在选择树种时应优先考虑乡土树种。     

重庆缙云山针阔混交林林隙树木更替规律研究

 研究了重庆缙云山大面积分布的亚热带次生性针阔混交林林隙树木更替规律,预测了该类型林林隙演替趋势。结果表明：马尾松(Pinus massoniana)种群表现出强烈的相互更替模式,四川大头茶(Gordonia acuminata)、四川山矾(Symplocos setchuanensis)等常绿阔叶树种自我更替与相互更替两种模式共存;林隙现实树木更替过程不能维持群落现有组成;Markov转移矩阵分析表明未来林冠层组成中马尾松种群将失去优势地位,整个群落将由针阔混交林向常绿阔叶林方向演替。     

宁镇山区不同森林土壤生物学特性的研究

对宁镇山区不同森林土壤微生物、土壤酶活性,营养元素的变化及凋落物的分解等生物学特性进行了探讨,结果表明,土壤微生物数量和6种土壤酶的生化活性在不同的季节的不同的林型土壤中均呈现出一定的变化规律,土壤中营养元素的含量随森林的生长周期而发生规律性的变化,并与土壤中微生物数量和土壤酶活性有显著的相关性,不同林地凋落物分解速率与其营养元素归还速率存在一定的时空差异,对次生栎林、毛竹林和杉木林土壤各生物学特性的比较表明,栎林土壤营养元素的含量最丰富,并具有较强的自肥调控能力,因此种植针阔混交林有利于防止针叶纯林的地力衰退现象。     

鼎湖山三种主要林型水文学过程中总有机碳浓度对比

为了解碳在森林内部以及群落演替过程中的转运动态 ,对鼎湖山 3种主要林型 (马尾松林 ,马尾松针阔混交林和季风常绿阔叶林 )森林水文学过程中总有机碳 (total organic carbon,TOC)浓度进行了一个雨季的观测 ,结果发现 :(1)穿透水中 TOC浓度相对大气降水中 TOC浓度的增量为 :季风常绿阔叶林 >马尾松针阔混交林 1>马尾松针阔混交林 2 >马尾松林 ;(2 )树干茎流平均 TOC浓度为 :马尾松林 >马尾松针阔混交林 2 >马尾松针阔混交林 1>季风常绿阔叶林 ;(3)各林内土壤水 TOC浓度差异不明显 ,但根系层 (2 5～ 30 cm)土壤水 TOC浓度均大于母质层 (5 0～ 80 cm) TOC浓度 ;(4 )马尾松林的溪水具有较高的 TOC浓度和较大的月际波动 ;(5 )总体上 ,整个森林水文学过程中 ,3种林型 TOC浓度变化趋势相似 ,均为 :树干茎流 >穿透水 >根系层土壤水 >母质层土壤水 >溪水 ,但变化幅度不同 :马尾松林的变化幅度最大 ,季风林的最小 ,而两个混交林居中。这表明 ,(1)森林演替过程中 ,林冠层结构、树种构成等的改变可能引起森林水文学过程中 TOC浓度的变化 ;(2 )森林水文学过程转运的碳主要储存在森林内部 ;(3)成熟森林的抗干扰能力高于先锋群落     

森林凋落物与大型土壤动物相关关系的研究

以针阔混交林及落叶阔叶林为例,探讨了森林凋落物与大型土壤动物的相关关系。研究表明,森林凋落物中大型土壤动物的个体数依林型、凋落物厚度、凋落物量不同而异,凋落物的分解程度影响大型土壤动物的种类、数量分布,凋落物中矿质元素含量与大型土壤动物体内矿质元素含量相关较好,凋落物中微量元素含量与大型土壤动物体内微量元素含量明显不相关。本研究为揭示大型土壤动物在凋落物分解中的作用,进而为森林的经营和保护提供科学依据。     

江苏常熟虞山土壤动物群落多样性研究

对江苏省常熟市虞山国家森林公园内的土壤动物进行了调查,共采得土壤动物样本 3916个,隶属于 5门 10纲,共26类群。蜱螨目、弹尾目和线虫纲是优势类群,占个体总数的88.22％,它们构成了该地区土壤动物的主体。对针阔混交林、竹林和茶园的土壤动物群落结构分析表明:土壤动物密度、类群数、多样性指数(H’)、密度-类群指数(DG)和多群落比较多样性指数(DIG)排序均为针阔混交林>茶园>竹林。茶园的均匀度指数最高。竹林的优势度指数最大。不同群落的相似性(q)分析表明,3种生境的土壤动物群落两两间的相似性指数q均大于0.5,都达到了中等相似水平。土壤动物的类群数垂直分布有明显差异,类群数向下逐渐减少。     

南亚热带马尾松-红椎混交林及其纯林土壤细菌群落结构与功能

营建乡土阔叶树种人工纯林和针阔混交林是我国亚热带地区森林经营的发展趋势,但对人工纯林和针阔混交林土壤细菌群落结构及功能知之甚少。本研究以南亚热带乡土针叶树种马尾松、阔叶树种红椎人工纯林及二者的混交林为对象,运用细菌16S rRNA基因高通量测序技术和PICRUSt基因功能预测,分析了3种人工林不同土层(0～20、20～40和40～60 cm)土壤细菌群落的结构与功能。结果表明: 混交林和马尾松林土壤细菌群落结构相似,但与红椎林差异显著,红椎林土壤细菌群落多样性、生物通路代谢功能和氮循环功能低于马尾松林和混交林;土壤全氮、硝态氮和C/N是导致红椎林与马尾松林和混交林土壤细菌群落结构及功能差异的主要土壤理化因子。就土壤细菌群落结构与功能而言,在该地区营造红椎和马尾松针阔混交林要优于红椎纯林。     

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.