广西弄岗北热带喀斯特季节性雨林林隙特征与空间分布

林隙是森林中一种普遍存在的小尺度森林干扰形式,对促进森林更新和循环演替具有重要作用。对热带喀斯特森林的林隙干扰目前还了解不多。该文采用Worldview-3高空间分辨率遥感影像结合地面调查,对弄岗喀斯特季节性雨林15 hm~2样地林隙干扰特征及其空间分布规律进行了研究。结果表明:样地内共解译到305个林隙,林隙的密度约为每公顷20个,林隙大小的变化范围为10～371 m~2,平均大小为52.3m~2,林隙面积占森林面积的10.6%;林隙在0～50 m尺度整体表现出聚集分布格局;林隙空间分布与大树(DBH≥10 cm)存在显著空间关联,与小树(DBH10 cm)和枯立木无显著空间关联;不同生态因子对林隙的数量分布和基本结构影响不同,对林隙数量分布影响最显著的包括凹凸度、干旱度指数、丰富度,而坡向、海拔、丰富度对林隙大小有显著影响,海拔、岩石裸露度、地形湿润度指数、干旱度指数、多度等5个生态因子对林隙周长有显著影响。研究结果表明林隙在喀斯特季节性雨林普遍存在,林隙的空间分布与特征存在着地形分异特征,是喀斯特独特的地质地貌和生境条件与喀斯特森林自身生物学特性综合作用的结果。     

The Wnt Inhibitor Sclerostin Is Up-regulated by Mechanical Unloading in Osteocytes in Vitro

Although bone responds to its mechanical environment, the cellular and molecular mechanisms underlying the response of the skeleton to mechanical unloading are not completely understood. Osteocytes are the most abundant but least understood cells in bones and are thought to be responsible for sensing stresses and strains in bone. Sclerostin, a product of the SOST gene, is produced postnatally primarily by osteocytes and is a negative regulator of bone formation. Recent studies show that SOST is mechanically regulated at both the mRNA and protein levels. During prolonged bed rest and immobilization, circulating sclerostin increases both in humans and in animal models, and its increase is associated with a decrease in parathyroid hormone. To investigate whether SOST/sclerostin up-regulation in mechanical unloading is a cell-autonomous response or a hormonal response to decreased parathyroid hormone levels, we subjected osteocytes to an in vitro unloading environment achieved by the NASA rotating wall vessel system. To perform these studies, we generated a novel osteocytic cell line (Ocy454) that produces high levels of SOST/sclerostin at early time points and in the absence of differentiation factors. Importantly, these osteocytes recapitulated the in vivo response to mechanical unloading with increased expression of SOST (3.4 ± 1.9-fold, p < 0.001), sclerostin (4.7 ± 0.1-fold, p < 0.001), and the receptor activator of nuclear factor κΒ ligand (RANKL)/osteoprotegerin (OPG) (2.5 ± 0.7-fold, p < 0.001) ratio. These data demonstrate for the first time a cell-autonomous increase in SOST/sclerostin and RANKL/OPG ratio in the setting of unloading. Thus, targeted osteocyte therapies could hold promise as novel osteoporosis and disuse-induced bone loss treatments by directly modulating the mechanosensing cells in bone.     

Combining the least cost path method with population genetic data and species distribution models to identify landscape connectivity during the late Quaternary in Himalayan hemlock

Himalayan hemlock (Tsuga dumosa) experienced a recolonization event during the Quaternary period; however, the specific dispersal routes are remain unknown. Recently, the least cost path (LCP) calculation coupled with population genetic data and species distribution models has been applied to reveal the landscape connectivity. In this study, we utilized the categorical LCP method, combining species distribution of three periods (the last interglacial, the last glacial maximum, and the current period) and locality with shared chloroplast, mitochondrial, and nuclear haplotypes, to identify the possible dispersal routes of T. dumosa in the late Quaternary. Then, both a coalescent estimate of migration rates among regional groups and establishment of genetic divergence pattern were conducted. After those analyses, we found that the species generally migrated along the southern slope of Himalaya across time periods and genomic makers, and higher degree of dispersal was in the present and mtDNA haplotype. Furthermore, the direction of range shifts and strong level of gene flow also imply the existence of Himalayan dispersal path, and low area of genetic divergence pattern suggests that there are not any obvious barriers against the dispersal pathway. Above all, we inferred that a dispersal route along the Himalaya Mountains could exist, which is an important supplement for the evolutionary history of T. dumosa. Finally, we believed that this integrative genetic and geospatial method would bring new implications for the evolutionary process and conservation priority of species in the Tibetan Plateau.     

有机磷农药的微生物降解研究进展

微生物因种类和代谢多样性在有机磷农药降解中表现出独特的优势。对微生物降解有机磷农药的机制、微生物的获得、基因工程菌的构建及研究展望进行了综述。     

青藏高原及其周边地区高山植物谱系地理学研究进展

青藏高原及其周边地区是世界上高山植物最丰富的地区,通过谱系地理学研究可以探讨高山植物演化历史与高原隆升和第四纪冰期的关系。根据对已经报道的36种高山植物的谱系地理分析,其谱系地理模式主要表现为:一、冰期退却到高原边缘的避难所,冰后期回迁到高原面;二、地理隔离造成冰期存在多处避难所(含微型避难所),冰后期发生局域性扩张。青藏高原在晚第三纪的快速隆升促进了物种的分化和成种,而第四纪冰期更是加剧了物种的快速分化,高原隆升和第四纪周期性气候波动是形成青藏高原高山植物现代谱系地理格局的主要原因。横断山脉地区作为第四纪冰期高山植物的主要避难所,在进化生物学和保护生物学方面具有重要启示。最后在物种选择、采样策略、基因片段选择和研究方法等4个方面提出青藏高原地区谱系地理学的研究方向。     

黄河源区玛多县草地退化成因分析

对黄河区玛多县草地退化的自然和人为因素作了深入分析。结果表明,过度放牧是导致玛多县草地退化的主要原因,自20世纪80年代末期以来,玛多县温度和降水较历史平均水平均有较大幅度的提高,其中温度增加表现为明显的暖冬现象,降水增加集中在春夏两季,水热条件的变化是向着利于草地恢复的方向发展的,由于玛多县是一个纯牧业县,扩大畜群数量是经济增长的必然选择,加上人口压力和当地藏族居民的传统价值观,驱使牧畜数量不断扩大,并在70年代末达到最大值,此后长期维持过牧状态,造成草地持续退化,过牧在导致草地退化的同时,也为鼠类的侵入创造了条件,从而加强了退化过程。     

Biological effects of amphiphilic copolymer nanoparticle-encapsulated multi-target chemotherapeutic drugs on MCF-7 human breast cancer cells

Introduction

Amphiphilic copolymer nanoparticle-encapsulated multi-target chemotherapeutic drugs have attracted considerable attention due to their favorable drug efficiency and potential application prospect. Studies have shown that an amphiphilic copolymer, methoxypoly(ethylene glycol)-poly(lactide-co-glycolide) modified with ε-polylysine, and encapsulated with hydrophilic doxorubicin, hydrophobic paclitaxel and survivin siRNA profoundly improved the therapeutic effect both in vitro and in vivo.

Objectives

To investigate how MCF-7 cells would response to the exposure of these nanoparticles over with time and assess the biological effects of these nanoparticles and their encapsulated drugs in a holistic manner.

Methods

MCF-7 cells were treated with PBS, nanocarrier and three encapsulated drugs, respectively. Metabolic alterations associated with nano-drugs exposure were investigated by performing untargeted NMR metabolomics with combination of targeted fatty acids analysis by GC-MS on cell extracts. Altered metabolic pathways were further validated by qRT-PCR approach.

Results

Copolymers showed great biocompatibility with cells as it induced transit metabolic disruptions without affecting cell survival rate. The rapid release of encapsulated doxorubicin resulted in inhibition of glycolysis and DNA synthesis, active proteolysis; these metabolic alternations were recovered after 10 h exposure. However, the combination use of multiple drugs consistently induced cell cycle arrest and apoptosis evidenced by reduction in glycolysis, active proteolysis, stimulated O-GlcNAcylation, reduced the PC:GPC ratio and fatty acids accumulation. Prolonged exposure to encapsulated-multiple-drugs also induced oxidative stress to cells.

Conclusion

These findings provide important insight into the biological effects of nanoparticles and their encapsulated drugs while demonstrate that metabolomics is a powerful approach to evaluate the biological effects of nano-drugs.

     

基于等级层次分析法的金沙江下游地区生态功能分区

金沙江下游地区是我国西南重要的生态环境保护区域,也是我国未来水电建设的重要区域,在西南民族经济和区域可持续发展等方面都具有十分重要的战略意义。该地区水能资源开发潜力巨大,是我国重要的能源基地,但是该地区生态环境相对脆弱。为了保护这些脆弱生态环境的地区,尽管国家和大多数省级层次的生态功能分区已经制定并颁布和实施,但是如何探索和制定区域、流域尺度的生态功能分区研究却为数不多。而大尺度的生态功能分区研究并不一定非常适合这一具体流域实际情况,所以小尺度典型流域的生态功能分区探索是非常必要的。基于金沙江下游地区的生态环境特征,运用空间分析的方法和技术,采用定性和定量分析相结合的等级层次分析法,对金沙江下游地区进行了生态功能分区。结果表明:金沙江下游地区可划分为2个生态区、6个生态亚区和29个生态功能区;以流域尺度上水源涵养、水土保持和生物多样性保护为主导生态系统功能,进行了重要生态功能分区,确定了金沙江下游地区具有重要意义的19个重要生态功能区域。该重点区域的划分对金沙江下游地区生态安全具有重要生态意义,可用于指导金沙江下游地区自然资源的有序开发利用和产业布局的合理配置,为金沙江下游地区生态环境保护提供科学依据,对维护金沙江下游地区的水电生态安全提供重要指导。     

青藏铁路温性草原区铁路运营对啮齿动物群落结构的影响

以青藏铁路海晏段的温性草原区为研究地点,通过铗日法确定距离铁路不同距离的区域中啮齿动物的种群密度和群落结构,分析啮齿动物群落结构与植物群落结构之间的关系,探讨温性草原区铁路运营对啮齿动物群落结构的影响。结果表明,研究区域内所捕获的啮齿动物有甘肃鼠兔、五趾跳鼠、长尾仓鼠和灰仓鼠;从1984 年铁路投入运营以来,没有发现铁路运营带来新物种的入侵;啮齿动物的种群密度和群落结构在距离铁路不同距离的样带之间有明显的不同,在铁路路基附近的种群密度、物种数、多样性指数均明显高于距离铁路0.5 km和1 km的区域,而均匀性指数在路基附近最小;在距离铁路不同距离的区域中植物群落的特征没有明显差异,啮齿动物群落特征与植物群落特征之间没有明显的相关性。引起铁路路基附近啮齿动物种群密度、物种数、多样性指数偏高的原因可能是铁路修建与运营为啮齿动物提供了合适的生存环境与额外的食物资源。因此,铁路建设及运营对啮齿动物的群落结构有一定程度的影响。