新疆卡拉麦里山有蹄类野生动物自然保护区夏季蒙古野驴适宜生境与种群数量评估

蒙古野驴(Equus hemionus hemionus)是亚洲内陆荒漠、半荒漠和荒漠草原区域的代表性物种。开展其种群数量调查和适宜生境研究可以为该物种的保护管理提供科学决策依据。本研究于2018和2019年夏季,采用样线法对新疆卡拉麦里山有蹄类自然保护区蒙古野驴的地理分布现状和种群数量进行了调查,采用Distance 7.0软件估算了蒙古野驴的种群密度和数量,并通过MaxEnt模型分析筛选环境变量,确定保护区蒙古野驴的适宜生境及其主要影响因子。结果表明: 调查中发现蒙古野驴718群、共4782头,有效分布位点363个。夏季蒙古野驴适宜生境主要位于保护区的中东部,面积为6737.5 km²,占整个保护区的45.4%,估算保护区夏季蒙古野驴的种群密度为(0.5±0.1)头·km^-2,保护区内蒙古野驴种群数量为(3246±575)头。MaxEnt模型的预测准确性较高,AUC的平均值为0.890。影响蒙古野驴分布的主要环境因子依次为: 距水源点距离、植被类型、距人类活动区距离、距G216国道的距离、海拔和最干季的降水量。最后,从水源点保护、核心区调整、野生动物通道监测和交通建设4个方面,对蒙古野驴种群的保护管理提出了建议。     

环状RNA的结构和功能特性及其与胃癌发生的关系

环状RNA是一类新发现以共价键形成环状结构的RNA分子,没有5'帽和3'尾,具有高度的序列保守性和稳定性,不易被核酸外切酶降解,在转录或转录后水平发挥基因表达调控的作用。近年来,已发现环状RNA与许多肿瘤包括胃癌发生密切相关。首先介绍环状RNA形成、分类、分子特征和功能,然后从环状RNA与胃癌发生、环状RNA与胃癌诊断、以及环状RNA在胃癌治疗中的作用等三个方面阐述环状RNA与胃癌的关系。     

Mating system and genetic diversity of a rare desert legume Ammopiptanthus nanus (Leguminosae)

Ammopiptanthus nanus is an endangered evergreen shrub endemic to the deserts of central Asia and plays an important role in delaying further desertification. We examined allozyme variation and AFLP diversity in A. Nanus populations and investigated the mating system of this species using progeny arrays assayed for poly-morphic allozyme loci. Mating system analysis in the Keyi'eryongke'er population showed low levels of out-crossing, and strong inbreeding depression. Low levels of genetic variation were detected at both population (allozyme, Pp=14.0%,A=1.14, He=0.031; AFLP, Pp=14.5%, Shannon's information index I=0.063) and species (allozyme, Pp=21.1%,A=1.21, He=0.040; AFLP, Pp=20.9%, I=0.083) levels; while moderate genetic differentia-tion existed among populations, as indicated by allozymes (GST=0.081) and AFLP (GST=0.151-0.193). Founder effect, bottlenecks in evolutionary history, the mixed mating system and co-ancestry may have influenced the level of genetic diversity in A. Nanus. Markers of both types provide new insights for conservation management, indicating that the Biao'ertuokuoyi and Keyi'eryongke'er populations should be given priority for in situ conser-vation and regarded as seed sources for ex situ conservation.     

Effects of elevated CO2 and temperature on leaf characteristics,photosynthesis and carbon storage in aboveground biomass of a boreal bioenergy crop (Phalaris arundinacea L.) under varying water regimes

This work examined the effects of elevated CO₂ and temperature and water regimes, alone and in interaction, on the leaf characteristics [leaf area (LA), specific leaf weight (SLW), leaf nitrogen content (N_L) based on LA], photosynthesis (light‐saturated net carbon fixation rate, P_sat) and carbon storage in aboveground biomass of leaves (C_l) and stem (C_s) for a perennial reed canary grass (Phalaris arundinacea L., Finnish local cultivar). For this purpose, plants were grown under different water regimes (ranging from high to low soil moisture) in climate‐controlled growth chambers under the elevated CO₂ and/or temperature (following a factorial design) over a whole growing season (May–September in 2009). The results showed that the elevated temperature increased the leaf growth, photosynthesis and carbon storage of aboveground biomass the most in the early growing periods, compared with ambient temperature. However, the plant growth declined rapidly thereafter with a lower carbon storage at the end of growing season. This was related to the accelerated phenology regulation and consequent earlier growth senescence. Consequently, the elevation of CO₂ increased the P_sat, LA and SLW during the growing season, with a significant concurrent increase in the carbon storage in aboveground biomass. Low soil moisture decreased the P_sat, leaf stomatal conductance, LA and carbon storage in above ground biomass compared with high and normal soil moisture. This water stress effect was the largest under the elevated temperature. The elevated CO₂ partially mitigated the adverse effects of high temperature and low soil moisture. However, the combination of elevated temperature and CO₂ did not significantly increase the carbon storage in aboveground biomass of the plants.     

不同园艺生产系统土壤可溶性有机氮差异

运用超速离心技术和KCl浸提法测定了不同园艺生产系统（有机(OS)、转换期(TS)、常规(CS)生产系统）土壤中可溶性有机氮（SON）、溶解性有机氮（DON）、游离氨基酸（FA A）等含量及其与土壤其他性质之间的关系.结果表明：供试土壤SON含量表现为OS>CS>TS,SON含量分别为土壤可溶性总氮（TSN）的42.9%、24.5%和18.4%,分别为土壤全氮的11.1%、11.9%和7.4%;OS、TS、CS生产系统土壤DON含量分别为4.38、1.68和3.26 mg·kg ^-1,分别占TSN的47.9%、22.1%和26.1%,占土壤全氮的2.9%、2.3%和3.6%;而FAA含量则表现为CS>TS>OS,分别占TSN和SON的1%～3%和2%～10%.相关分析表明,TSN、SON及FAA与全氮、全碳、硝态氮、铵态氮等各养分之间均有极显著相关关系（P<0.01）.因此,不同园艺生产系统的管理方式改变了土壤SON的含量及其特性.     

Elevated CO2 alters the feeding behaviour of the pea aphid by modifying the physical and chemical resistance of Medicago truncatula

Elevated CO₂ compromises the resistance of leguminous plants against chewing insects, but little is known about whether elevated CO₂ modifies the resistance against phloem‐sucking insects or whether it has contrasting effects on the resistance of legumes that differ in biological nitrogen fixation. We tested the hypothesis that the physical and chemical resistance against aphids would be increased in Jemalong (a wild type of Medicago truncatula) but would be decreased in dnf1 (a mutant without biological nitrogen fixation) by elevated CO₂. The non‐glandular and glandular trichome density of Jemalong plants increased under elevated CO₂, resulting in prolonged aphid probing. In contrast, dnf1 plants tended to decrease foliar trichome density under elevated CO₂, resulting in less surface and epidermal resistance to aphids. Elevated CO₂ enhanced the ineffective salicylic acid‐dependent defence pathway but decreased the effective jasmonic acid/ethylene‐dependent defence pathway in aphid‐infested Jemalong plants. Therefore, aphid probing time decreased and the duration of phloem sap ingestion increased on Jemalong under elevated CO₂, which, in turn, increased aphid growth rate. Overall, our results suggest that elevated CO₂ decreases the chemical resistance of wild‐type M. truncatula against aphids, and that the host's biological nitrogen fixation ability is central to this effect.     

浙江省衢州市绿金指数核算研究

衢州市是浙江省重要生态屏障,"绿水青山"资源非常丰富。开展绿金指数核算可以总体测定和衡量衢州市"绿水青山"与"金山银山"之间转化关系的成果,助力衢州市更好地全面实践"两山"理论。基于生态系统生产总值(GEP)的核算结果与国内生产总值(GDP)的比值,浙江省衢州市绿金指数核算结果显示:2015年衢州市绿金指数为3.04,说明衢州市"绿水青山"资源价值远远大于"金山银山",生态要素转变为生产要素、生态财富转变为物质财富的潜力巨大;与其他地区比较来看,衢州市绿金指数远高于全国水平(1.01);与所在的浙江省及长三角的上海市和江苏省相比,衢州市领先地位突出,分别是浙江、上海和江苏的6倍、22倍和10倍;与相邻的安徽和江西相比,衢州市优势明显。研究认为衢州市需要利用丰富的"绿水青山"资源,积极探索打通"绿水青山"向"金山银山"的转化通道,真正实现经济效益、生态效益、社会效益共赢。     

云南盘鳇消化系统解剖学、组织学及消化酶活性研究

采用形态学、组织学及酶学方法对云南盘逗(Discogobio yunnanensis)成体消化系统进行研究。结果表明, 云南盘逗消化系统有以下特征: 口下位, 口腔上皮分布有较多味蕾及杯状细胞, 食道粗大, 含有大量黏液细胞, 无胃, 肠道较长, 盘旋于体腔中, 成鱼盘旋10回, 肠道系数为5.06±0.61, 肠分为前中后三段, 肠腔中密布肠绒毛。消化腺为肝胰脏, 肝脏分为左右两叶, 胰脏弥散分布在肝脏中。消化系统不同部位消化酶活性大小不同, 脂肪酶活性: 肝胰脏>前肠>中肠>后肠, 胰蛋白酶、淀粉酶、碱性磷酸酶活性: 前肠>中肠>肝胰脏>后肠。云南盘逗口下位, 食道粗短, 肠道细长, 肠绒毛丰富, 肠道含较高的胰蛋白酶和淀粉酶活性, 消化系统所具有的这些特征与其以固着藻类为食有关。     

Visualization of pseudogenes in intracellular bacteria reveals the different tracks to gene destruction

Background  

Pseudogenes reveal ancestral gene functions. Some obligate intracellular bacteria, such as Mycobacterium leprae and Rickettsia spp., carry substantial fractions of pseudogenes. Until recently, horizontal gene transfers were considered to be rare events in obligate host-associated bacteria.     

基于航片的黄土高原丘陵沟壑区沟谷侵蚀定量监测

基于黄土丘陵沟壑区1979和1993年两期航片和地形图数据,采用数字影像测量方法生成数字正射影像图和数字高程模型,以地理信息系统为手段,研究了黄土丘陵沟壑区的一条沟谷在中尺度时间上的面积及深度变化,并对该变化的空间差异以及