国家公园及周边地区人为扰动强度的时空变化与驱动因素——以三江源国家公园为例

科学评价国家公园及周边地区人为扰动强度及其影响,是提升各种人类活动空间监管准度的基本前提,对保障国家公园可持续发展和永续利用、牢筑国家生态安全屏障功能具有重要价值。以三江源国家公园为例,运用改进的人为扰动强度指数测算模型和人为扰动行为调查台账数据库,定量评估1980—2018年国家公园及周边地区人为扰动强度的时空变化过程,诊断影响一般扰动及失范扰动的驱动力与主要因素,探讨人为扰动监管存在的主要问题及优化建议。研究结果显示：1980—2018年三江源国家公园内人为扰动强度提升3.237%,长江源园区人为扰动强度显著低于澜沧江源和黄河源园区;2000—2010年人为扰动增长较为显著,而在2010—2018年趋于平稳,表明2010年以来生态保护措施和监管执法尺度更趋严格,并对三江源人为扰动过程产生明显遏制;以交通设施为主的基础设施建设、人口城镇化及原住民传统生产生活活动、游憩利用活动是人为扰动强度变化的主要驱动力;道路及沿线配套设施、原住民生活设施和水电设施建设是国家公园内失范人为扰动的主因。针对三江源国家公园及周边地区人为扰动驱动因素与监管问题,建议实施精细化用途分类分区管制、激活并规范市...     

Erebosis,a new cell death mechanism during homeostatic turnover of gut enterocytes

Many adult tissues are composed of differentiated cells and stem cells, each working in a coordinated manner to maintain tissue homeostasis during physiological cell turnover. Old differentiated cells are believed to typically die by apoptosis. Here, we discovered a previously uncharacterized, new phenomenon, which we name erebosis based on the ancient Greek word erebos (“complete darkness”), in the gut enterocytes of adult Drosophila. Cells that undergo erebosis lose cytoskeleton, cell adhesion, organelles and fluorescent proteins, but accumulate Angiotensin-converting enzyme (Ance). Their nuclei become flat and occasionally difficult to detect. Erebotic cells do not have characteristic features of apoptosis, necrosis, or autophagic cell death. Inhibition of apoptosis prevents neither the gut cell turnover nor erebosis. We hypothesize that erebosis is a cell death mechanism for the enterocyte flux to mediate tissue homeostasis in the gut.

It has been believed that gut enterocytes continuously die through apoptosis. However, this study shows that gut enterocytes die through a novel cell death mechanism, named erebosis. Erobotic cells lack the characteristic features of apoptotic, necrotic or autophagic cell death; instead they lose their cytoskeleton, cell adhesion and organelles, and their nuclei become flat and indistinct.     

青藏高原生态屏障区生活垃圾治理生态环境风险及应对路径——以青海省为例

生活垃圾治理失效导致的污染胁迫已成为青藏高原生态安全屏障建设面临的突出威胁,精准评估城乡生活垃圾治理的生态环境风险并科学制定应对路径,对改善人居环境品质、筑牢生态安全屏障具有重要意义。以青海省4306个居民点为研究对象,在定量测度城乡各类生活垃圾的产生量及其治理水平基础上,从生活垃圾治理体系的收集、转运与处理全过程视角,综合考虑危险度、暴露度、脆弱度因子构建生态环境风险评价指标体系,应用基于主客观综合赋权的TOPSIS方法和风险管控障碍度评价方法,多尺度评价生活垃圾治理生态环境风险并识别管控阻滞因子。结果显示：青海省城乡生活垃圾产生呈整体分散、局部组团式集中分布特征,全省生活垃圾集中治理率仅62.33%;全省生活垃圾治理的生态环境风险总体处于中风险等级,属于中高风险及高风险等级的居民点占36.90%,且河湟谷地区向柴达木盆地区、环青海湖及祁连山地区和青南高原地区呈风险递增;现行生活垃圾治理体系在镇级转运环节的生态环境风险最高,在祁连山脉、昆仑山脉东段以及青南高原峡谷地带转运风险突出;自然地理环境高寒性、分散式垃圾处理技术滞后性是风险管控的主要阻滞因子。建议以生活垃圾全处置和生态环境零胁...     

青藏高原生态屏障区环境基本公共服务的非均衡性及其成因——基于青海村镇居民点的实证分析

环境基本公共服务是青藏高原生态屏障区生态环境治理及农牧民人居环境品质提升的关键环节,揭示其配置均衡状态及失效原因,对提升青藏高原环境基本公共服务均等化水平、降低生态屏障区内人类活动的生态环境胁迫风险具有重要意义。以青海省4315个村镇居民点为对象,选取生活垃圾处理、生活污水处理、卫生户厕改造3项特征指标,定量测度村镇环境基本公共服务配置非均衡性,运用有序多分类及二元逻辑斯蒂回归模型解析非均衡性的生成原因。结果显示：青海环境基本公共服务水平总体偏低,处于低和极低等级的村镇居民点占37.13%和37.84%;环境基本公共服务非均衡性受配置成本、人口社会、经济收入和基层管理因素的多重影响,自然地理的高寒性和交通区位的偏远性是生成非均衡性的重要因素;人口社会因素的规模报酬递增效应使非均衡性加剧,大分散、小聚居的农牧民定居点通常是服务配置的弱势区域,经济收入和基层管理因素分别是非均衡性加剧的内因和外因。建议在青藏高原生态屏障区实施递进式均衡配置模式及适应性管理,建立就地消纳与跨区处理结合的弹性生活垃圾处置体系,推广耐低温分散化污水处置模式和生态化处置技术体系,适应高寒环境的户厕改造技术研发和农牧...     

Relationships Between Population Growth and Population Density in Monocultures of Larix leptolepis

One year-old Japanese larch (Larix leptolepis) seedlings were planted in a nursery from 1984 to 1986 at four density levels with four replicates in order to investigate the relationships between plant growth and density of survivors. As the results shown, self-thinning occurred severely in populations growing at high densities. The rate of the self-thinning followed a trajectory defined by the 3/2 power law. The relationship between mean dry weight per tree and population density at a given stage of growth followed the reciprocal equation and power equation at early experimental stages, but changed gradually to follow the 3/2 power law as plants grew further. Shch a change was mainly caused by the constant basal area per ms and decreased growth of tree height along a gradient of the density. The relationship between tree height (h) and density (p) also be discussed and in the 3/2 power law system it could be described by an equation consisting of h=αp（-1/2） where α is a constant.     

Change of thermal stability of colicin E7 triggered by acidic pH suggests the existence of unfolded intermediate during the membrane-translocation phase

Purified colicin E7 was analyzed by CD spectrum and gel filtration chromatography in a mimicking membrane-translocation phase. It was found that the CD spectra of colicin E7 at pH 7 and pH 2.5 were similar. Although the melting temperature of the protein shifted from 54.5°C to 34°C at low pH, the thermal denaturation curves of colicin E7 at different pH conditions still fit a two-state model. These experimental results imply that a minor structural change, triggered by acidic pH, for instance, may reduce the energy required for protein melting. In contrast to the minor change in secondary structure at different pH conditions, we observed that, in vitro, all monomeric colicin E7s converted into multimer-like conformations after recovering from the partial unfolding process. This multimeric form of colicin can only be dissociated by formamide and guanidine hydrochloride, indicating that this protein complex is indeed formed by aggregation of the monomeric colicins. Most interestingly, the aggregated colicins still perform in vivo bacteriocidal activity. We suggest that in a partial unfolding state the colicin is prepared for binding to the specific targets for translocation through the membrane. However, in the absence of specific targets in vitro these unfold intermediates may therefore aggregate into the multimeric form of colicins. Proteins 32:17–25, 1998. © 1998 Wiley-Liss, Inc.     

The utility of internally transcribed spacer 2 DNA sequences of the nuclear ribosomal gene for distinguishing sibling species of Trichogramma

The usefulness of the internally transcribed spacer 2 (ITS2) of the nuclear ribosomal gene complex is tested for providing taxonomic characters to identify Trichogramma species. The ITS2 sequences of a group of sibling species of the T. deion/T. pretiosum complexes were determined. A simple and precise identification key to the species of these assemblages was constructed using as taxonomic characters the size of the ITS2 and the difference in restriction length polymorphism of species with similarly sized ITS2. Individual wasps can be identified by amplification of their ITS2 with general primers, determining the size of the PCR product using standard agarose electrophoresis, followed in some species by a DNA-digestion with a restriction enzyme. Because this system works well for a number of closely related species we are hopeful that similar PCR-based identification can be extended to all species of the genus once their ITS2 sequences have been determined. The advantage of this identification system over the morphology-based system is that non-specialists are able to quickly and cheaply identify individual specimens. In addition, species specific primers were tested for the two most common species of these groups (i.e. T. pretiosum and T. deion). These primers can be used either as a direct identification tool or as a method to confirm the identification using the general key. The phylogeny of this group of wasps was also analyzed based on the ITS2 sequence.     

人体半导体激光外照射的疗效及其作用机理研究：血浆肽类神经递质 …

本工作应用半导体激光（６５０ｎｍ,１５－２０ｍＷ,ＣＷ）穴位照射人体双侧“扶突”穴后,同步观察其在血浆肽类神经递质上的变化以及其在血液黏度,免疫功能,抗氧化体系等方面的影响及其相关性。结果发现β－Ｅｐ有非常显著性的下降（Ｐ＜０．０２）,患者的ＮＫ细胞活性,在照射后即有所显著性地提高（Ｐ＜０．０５）。患者的超氧化物歧化酶（ＳＯＤ）亦有同步增加（Ｐ＜０．０５）。此外在血液流变学方面,发现血粘度指标中有