基于MODIS/NDVI时间序列的森林灾害快速评估方法——以贵州省为例

以2005—2008年中分辨率成像光谱仪(MODIS)的归一化植被指数(NDVI)数据集为主要数据源构建研究区时间序列,结合统计学分析方法设计一套快速有效的森林灾害评估体系,用以探测森林资源损失的空间分布范围与灾害等级,并利用森林资源雪凝灾害损失的实际调查数据对评估结果进行一致性检验。结果表明:通过计算2005—2007年研究区所有森林像元的平均值R珔2005-2007和平均绝对偏差δall,确定森林灾害阈值DT为0.048;利用该阈值,获取2008年受灾较重的森林空间分布,主要密集分布在贵州省东南部和东北部,包括了黔南自治州、黔东南自治州和铜仁市等地区;受灾森林像元数占总森林像元数的28.6%,高于凝冻灾害森林资源损失实际调查结果(17.7%);在县域尺度上,根据MODIS/NDVI关键期影像获取的森林资源损失区域和灾害等级,确定德江、沿河和都匀等11个重度受灾县(市、区)和湄潭、榕江和桐梓等10个中度受灾县(市、区),与小班调查结果具有较高的一致性,其Kappa系数为0.86。方法为大区域尺度的森林灾害快速评估提供了一种新思路。     

洞庭湖区东方田鼠种群暴发期间的行为特征观察

2007年6月下旬洞庭湖区东方田鼠(Microtus fortis calamorum)再度暴发,作者观察到其种群暴发期间的迁移、栖息与取食行为具有典型的"逃难"与临时"集群"特征,大多数东方田鼠在迁移过程中死亡,迁到大堤的鼠聚集在大石下、木头下、矮灌木和草丛等较隐蔽场所,一个月后扩散到农田和荒地中,多扩散到杂草茂盛的荒地内。迁移过程中不仅取食农作物,而且取食老树皮等,农作物损失严重。了解其在迁移期间的行为特征,可为了解东方田鼠的生活史适应特性和防控东方田鼠危害提供依据。     

豫西黄土高原农作区棕色田鼠对农作物的危害及经济阈值的研究

棕色田鼠是河南西部农作区的主要危害鼠种。1993年8月～1995年3月在河南省灵宝市程村乡对棕色田鼠的密度及其对农作物的危害程度进行了调查研究 , 并对小麦、黄豆2种不同作物地防治棕色田鼠的经济阈值进行了初步估算。把棕色田鼠对这2种作物的危害分为4个等级, 小麦地防治棕色田鼠的经济阈值为133.9只/hm²; 黄豆地防治棕色田鼠的经济 阈值为181.1 只/hm²,达到此密度应进行防治,否则将造成不同程度的经济损失。     

人鼠对决何时休？

鼠类是生态系统中的主要成员,在草地生态系统中起着重要的作用。20世纪70年代以来,我国北方草原地区暴发过数次严重的鼠害。在灾害发生的高峰年,害鼠危害草场的面积占可利用面积的60%,即使在正常年份也达     

内蒙古草场鼠害的基本特征及其生态对策

天然草场是发展畜牧业的重要基地。本区草场面积辽阔,资源丰富,具有很大的生产潜力。对于此类可再生资源的利用和保护,从东部的草原草场到西部荒漠草场,目前均还存在不同程度的草场退化、沙化以及与此有关的鼠害问题。鼠患严重地区,如呼伦贝尔草原,据有关单位1971-1982年统计资料,在布氏田鼠(Microtus brandti)种群数量增长年份,受害草场达可利用面积的54%;一般年份亦有10-20%。     

甘肃鼢鼠和根田鼠听域研究

用电生理学方法对甘肃鼢鼠和根田鼠的听性脑干反应(ABR)的反应阈值做了测定,以确定甘肃鼢鼠和根田鼠听域.结果 表明甘肃鼢鼠听力敏感频率为12 kHz,根田鼠的听力敏感频率为16～32 kHz.甘肃鼢鼠和根田鼠听性脑干电位测定结果表明地下鼠和地面鼠低频高频听力阈值存在差异,地下鼠对中低频声波敏感.     

实验室饲养和野外生存条件下东方田鼠肠道菌群的多样性

目的探讨实验室饲养和野外生存条件下东方田鼠肠道菌群的分布和差异。方法应用高通量测序技术测定实验室饲养和野外捕捉东方田鼠的肠道细菌16S rDNA-V4-V5区序列,统计操作分类单元(OTUs)数量,分析菌群物种丰度、分布及差异性。结果稀疏曲线表明取样数量合理,测序充分。在门水平,实验室饲养和野外生存的肠道菌群分布和占比基本相似,实验组有1个独有的门,即黏胶球形菌门(Lentisphaerae),野生组有3个独有的门,分别是梭杆菌门(Fusobacteria)、奇古菌门(Thaumarchaeota)和未分类的门,丰度差异最大的为软壁菌门(Tenericutes)。在属水平,野外东方田鼠肠道细菌较实验室饲养的丰富,丰度差异最大的为瘤胃球菌属(Ruminococcus)。结论获得了实验室饲养和野外生存条件下东方田鼠肠道菌群结构和差异性,进一步充实了东方田鼠基础生物学数据。     

布氏田鼠对草场产草量的危害及防治阈值研究

布氏田鼠(Microtus brandti)为内蒙古典型草原区的主要牧业害鼠,确定该鼠对草场植被的危害过程及相应危害量是寻求防治阈值的基础。1986年至1987年我们在内蒙古太仆寺旗建立野外围栏观测条件,并结合室内试验进行研究。现将结果简报于后。     

洞庭湖东方田鼠肥满度时空特征及与降水、温度、归一化植被指数的关系研究

为明确洞庭湖区东方田鼠Microtus fortis肥满度的时空特征及其与东方田鼠常用预警生态因子的关系,采用夹日法对洞庭湖7个调查区域不同生境的东方田鼠进行调查分析;收集洞庭湖区降水、温度、归一化植被指数(NDVI)等环境因子数据,分析不同性别东方田鼠肥满度与降水、温度、NDVI的关系。结果表明:1)不同性别东方田鼠肥满度时空特征较一致,春季和冬季不同生境雌雄东方田鼠的差异有高度统计学意义;在洲滩芦苇生境,雄雌东方田鼠在各季节间的差异有高度统计学意义;在洲滩苔草+芦苇+杨树生境,雄性肥满度各季节间的差异有统计学意义。2)雌性肥满度与季平均降水量呈显著正相关,雄性肥满度与季平均降水量无显著的相关关系。3)雌性和雄性的肥满度与季平均温度均无显著的相关关系。4)雌性肥满度与农田生境的NDVI呈显著正相关,雄性肥满度与农田生境的NDVI无显著的相关关系;雌性和雄性的肥满度与洲滩生境的NDVI均无显著的相关关系。研究认为,洞庭湖东方田鼠肥满度可以在一定程度上反映其对环境压力的反应,雌性对不利环境较雄性更加敏感,但在特定情况下,栖息地、食物可获得性等通过影响雌性东方田鼠肥满度,进一步影响东方田鼠种群增长。     

东方田鼠乳酸脱氢酶同工酶的研究

目的研究乳酸脱氢同工酶在3种东方田鼠不同器官的分布.方法以大鼠和小鼠作对照,用聚丙烯酰胺凝胶电泳对3个不同地区的东方田鼠(Microtusfortis)血清、红细胞、肝脏、肾脏、肺中乳酸脱氢酶(LDH)同工酶进行分析.结果东方田鼠血浆中只有LDH5,血清中湖南洞庭湖地区、宁夏青铜峡地区的东方田鼠也只有LDH5,而东北地区的东方田鼠则含有LDH1和LDH5,3个地区的东方田鼠肾脏和肺中都有5种LDH同工酶,肝脏中除东北地区的东方田鼠含5种LDH同工酶外,其余两种东方田鼠均以LDH5为主(LDH5占95%以上).结论东北地区东方田鼠乳酸脱氢酶同工酶谱与其他两地的东方田鼠不相同.     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.