肿瘤干细胞表面标志物及主要信号通路

肿瘤干细胞是存在于肿瘤组织中的具有自我更新、增殖、分化的部分细胞群,对肿瘤的发生、发展有十分重要的作用. 肿瘤干细胞特异的表面分子及其异常活化的信号通路,是其区别于其他肿瘤细胞的特性.寻找和鉴定特异的肿瘤干细胞的表面标志物,从而识别肿瘤组织中的肿瘤干细胞,并进行相关信号调控机制研究,是肿瘤早期诊断及肿瘤干细胞靶向治疗的关键. 本文简要概述了肿瘤干细胞相关的表面标志物及信号通路的研究进展,旨在为进一步开展针对肿瘤干细胞的抗体靶向治疗提供新思路.     

Effects of dew on eco-physiological traits and leaf structures of Leymus chinensis and Agropyron cristatum grown under drought stress

Aims To investigate the effects of dew on plants, we conducted the experiment to determine the physiological characteristics and leaf structures of Leymus chinensis and Agropyron cristatum in response to increasing dew under drought stress.Methods Four treatments (no dew, three times dew and five times dew per week under drought stress, and well-watering) were designed to examine leaf relative water content, water potential, net photosynthetic rate, water use efficiency, biomass, and leaf structures of L. chinensis and A. cristatum. Important findings There was a significant increase in the relative water content and water potential by simulated dew increase for two plants species under drought stress (p < 0.05). For A. cristatum, simulated dew increase significantly enhanced the net photosynthetic rate, stomatal conductance, and transpiration rate of plants under drought stress (p < 0.05). On the other hand, there was no significant difference in the stomatal conductance and transpiration rate for L. chinensis among treatments. Simulated dew increase improved the aboveground biomass and root biomass of two species. The ratio of yellow leaves to the total leaves was decreased by simulated dew increase for two species. Dew increase also protected leaf structures against the drought stress, suggesting that the dew increase can slow down the death process of leaves resulted from drought stress. Therefore, the study demonstrated that dew increased the available water for the leaves of L. chinensis and A. cristatum grown in the drought stress and thus had positive effects on the photosynthesis, water physiology and plant development.     

Distribution,community characteristics and classification of Stipa tianschanica var. klemenzii steppe in China

Stipa tianschanica var. klemenzii steppe is the most typical formation of desert steppe in China. Based on the primary plots data obtained from fieldworks during the growing seasons from 2010 to 2016 as well as some earlier records, we studied the Stipa tianschanica var. klemenzii steppe across China systematically, including the eco-geographical distributions, community characteristics and classifications. The results showed that S. tianschanica var. klemenzii steppe distributed mainly on the Ulan Qab Plateau and western Xilin Gol Plateau. Due to the arid biotope of S. tianschanica var. klemenzii steppe, quantitative characteristics of the assemblage including height, coverage, biomass and species richness were normally lower than that of most Stipa formations in Eurasian steppe region. Moreover, 165 seed plants belonging to 85 genera and 29 families were recorded in the 80 study sites, in which rare species (occurrence frequency <20%) made up 87% of the total plants while common species and constant species could only be found occasionally. Species with the occurrence frequency exceeding 50% included S. tianschanica var. klemenzii, Convolvulus ammannii, Cleistogenes songorica, Allium tenuissimum. In addition, Hemicryptophyte and therophyte were the two dominant life forms, covering 55% and 20% of the species, respectively. As for the ecological type of water, typical xerophytes accounted for 47% of all species which is followed by super-xerophytes and meso-xerophytes. Middle Asian areal-type and east Palaeo-North areal-type were the two major floristic elements, containing 37% and 26% of the species, respectively. Based on the life forms and dominances of the species within the community, S. tianschanica var. klemenzii steppe in China could be classified into 6 association groups, 29 associations.     

中国石生针茅草原的分布、群落特征和分类北大核心CSCD

石生针茅(Stipa tianschanica var.klemenzii)草原是中国荒漠草原最具代表性的植被类型。该文利用2010–2016年生长季的野外调查数据并结合已有文献资料,对中国石生针茅草原的生态地理分布、群落学特征以及类型划分进行了全面系统的分析。结果表明:中国石生针茅草原主要分布在内蒙古锡林郭勒高原西部和乌兰察布高原,常分布在棕钙土基质的高平原上;分布区气候干旱,群落高度、盖度、生物量和物种丰富度较低;根据80个样地的数据统计,石生针茅草原共记录到种子植物165种,隶属于29科85属,其中以偶见种(存在度<20%)居多,占87%,常见种和恒有种较少,存在度大于50%的物种有石生针茅、银灰旋花(Convolvulus ammannii)、无芒隐子草(Cleistogenes songorica)、细叶韭(Allium tenuissimum);物种生活型以地面芽植物和一年生植物居多,分别占55%和20%;水分生态类型以典型旱生植物居多,占47%,其次为强旱生植物和中旱生植物;区系地理成分以亚洲中部和东古北极成分为多,分别占37%和26%;根据生活型和物种的优势度,石生针茅群系可划分为6个群丛组、29个群丛。     

革兰氏阴性菌脂蛋白Lol系统转运蛋白的功能及表面展示分泌机制

细菌脂蛋白是细胞膜的重要组成成分,在革兰氏阴性菌的生理及致病性中扮演着重要的角色。革兰氏阴性菌中已知负责胞内脂蛋白转运的是Lol(Localization of lipoprotein)系统。该系统识别成熟脂蛋白的分泌信号,将外膜脂蛋白转运并定位于细胞外膜内侧。近年来的研究发现,跨细胞外膜进行表面展示的脂蛋白实际上在革兰氏阴性菌中广泛存在,其分泌机制开始成为研究热点。为了对革兰氏阴性菌中脂蛋白分泌机制的研究现状有一个系统全面的了解,本文概述了脂蛋白转运过程中Lol系统5个转运蛋白的功能与保守性、不同细菌中脂蛋白分泌信号的差异以及表面展示脂蛋白可能的分泌机制。     

中国秀体溞属常见种类记述

秀体溞是枝角类中重要的属,其分类一直存在较大分歧。目前我国秀体溞属有10个种,即短尾秀体溞Diaphanosoma brachyurum Liévin,1848、兴凯秀体溞D.chankensis Ueno,1939、奥氏秀体溞D.orghidani Negrea,1982、模糊秀体溞D.dubium Manujlova,1964、杜蒙特秀体溞D.dumonti Korovchinsky,1996、镰角秀体溞D.excisum Sars,1885、蒙古秀体溞D.mongolianum Ueno,1938、多刺秀体溞D.sarsi Richard,1894、大眼秀体溞D.macrophtalma Korovchinsky & Mirabdullaev,1995、热带秀体溞D.tropicum Korovchinsky,1998。在综合现有文献和研究模式标本的基础上,建立了上述10个种的分类检索表,并对我国最为常见的4个种:短尾秀体溞D.brachyurum Lievin,1848、奥氏秀体溞D.orghidani Negrea,1982、模糊秀体溞D.dubium Manujlova,1964、镰角秀体溞D.excisum Sars,1885的形态特征和地理分布进行了详细描述。分析了目前我国与国际在秀体溞分类上的一些异同,讨论了我国秀体溞分类中存在的同名异种或同种异名的问题。     

光环境对胡桃楸幼苗生长与光合作用的影响

为了解胡桃楸幼苗对光的需求及适应规律,采用Li-6400便携式光合测定系统研究了不同光环境处理（100%、60%、30％和15%自然光）条件下3年生胡桃楸幼苗（适应1年后）叶片光合能力的季节变化及其对光强的响应.结果表明：在春季,胡桃楸幼苗对光反应不敏感,夏季和秋季随着光强的增加,叶片的最大光合速率、最大羧化速率和最大电子传递速率均显著增加（P<0.05）.光饱和点随光强的下降而降低（P<0.05）,表观量子效率、暗呼吸速率和光补偿点在不同光环境下未发现显著差异.100%和60%自然光处理的幼苗相对生长率差异不显著,但是随着光强下降,相对生长率显著下降（P<0.05）,为60%>30％>15%自然光处理.胡桃楸幼苗对不同的光环境表现出较强的适应性和可塑性;同时,通过降低光饱和点和减少碳积累,也能适应15%～30％自然光环境.     

闽南地区常见彩叶植物的色彩分类及应用初探

本文从色彩的角度把闽南地区123种常见彩叶植物分为红色、黄色和银色三个系列。红色系列有36种,占29%;黄色系列有45种,占37%;银色系列有42种,占34%。本分类法简单易操作,便于选择与应用。文中还探讨彩叶植物的主要特征及其在园林设计和园林绿化中的应用,并提出合理化建议。     

基于Fiedler向量的基因表达谱数据分类方法

尝试将一种基于图的Fiedler向量的聚类算法引入到基因表达谱数据的肿瘤分类中来。该方法将分属不同类的所有样本通过高斯权构造Laplace完全图,经SVD分解后获得Fiedler向量,利用各样本所对应的Fiedler向量分量的符号差异来进行基因表达谱数据的分类。通过模拟数据仿真实验和对白血病两个亚型(ALL与AML)及结肠癌真实数据实验,证明了这一方法的有效性。     

酵母表面展示脂肪酶合成己二酸二异辛酯

展示酶的酵母细胞既具有固定化酶的优点,又有制备简单、成本较低的特点.采用表面展示南极假丝酵母脂肪酶B (Candida antarctica lipase B,CALB)的毕赤酵母细胞催化合成己二酸二异辛酯(Diisooctyl adipate,DIOA),对该反应体系进行优化,并实现了初步工艺放大制备.经条件优化后,在10mL反应体系中,DIOA的产率可达85.0％.该工艺放大到200mL反应体系时,DIOA产率可达97.8％.经减压蒸馏,DIOA纯度可达到98.2％.该酵母表面展示脂肪酶在合成绿色润滑油己二酸二异辛酯中具有良好应用前景.