Pericytes and perivascular microglial cells in the basal forebrain of the neonatal rabbit

Summary Three types of pericytes outline the vascular bed in Golgi preparations of the newborn rabbit brain. Elongate cells (Type I) are restricted to capillaries, elements resembling smooth muscle cells (Type II) surround vessels of intermediate size, and large flat forms (Type III) cover the surface of arterioles and venules. Electron microscopy shows all types to be located within a well defined perivascular basement membrane. It also reveals the presence of filaments in the cytoplasm of some pericytes resembling the myofilaments of smooth muscle cells. It suggests the possibility that some pericytes are capable of contraction and may participate in regulating blood flow in small vessels.Microglia cells bear no resemblance to pericytes in terms of their shape, distribution or staining characteristics. Microglia cells are located outside the vascular basement membrane (external basal lamina) in the brain parenchyma, and they vary in form according to their location and the character of the surrounding extracellular space. This study does not support the hypothesis that microglia cells arise from pericytes but indicates that they originate either by in situ division or from hematogenous elements that enter the brain by crossing the vessel wall.Support provided by N.I.H. Grants No. NS 10864 and NS 07938 from the U.S. Public Health Service.     

基于SPEI指数的淮河流域干旱时空演变特征及影响研究

运用淮河流域149个气象站1962—2016年逐日气温、降水资料以及历史旱情资料,基于SPEI、EOF和M-K等方法分析淮河流域的干旱时空特征,研究干旱的时空演变规律并揭示其对农业生产的影响。结果表明:(1)基于SPEI得到的干旱频次与受灾、成灾面积的相关性通过了0.1的显著性水平检验,表明SPEI在淮河流域具有较好的适用性;(2)淮河流域干旱发生时间差异明显,干旱次数呈现波动变化,发生重旱和特旱次数占总干旱的比重是20.0%,其中重旱和特旱在1960s比重最大(24.8%),其次是2010s(15.8%),在1980s比重最低(10.0%);(3)干旱的空间分布差异大,淮河流域干旱频率在27.76%—36.04%之间,西北部和东南部发生干旱强度较西南部、东北部及中部低;(4)淮河流域总体呈干旱化的趋势,从中部到四周呈现由高到低递减的趋势变化,且空间模态表现为全区一致型、南北相反型和东西相反型。     

哈尔滨城市和乡村青年居民肠道菌群多样性研究

【目的】分析居住于哈尔滨城市和乡村的青年居民肠道菌群多样性的异同。【方法】采用PCR和DGGE技术相结合的方法对生活于哈尔滨城市和乡村的青年志愿者肠道菌群多样性进行研究。基于DGGE指纹图谱,分别使用聚类和PCA分析对志愿者肠道微生物相似性进行分析,使用Shannon-Weine多样性指数(H′)、丰度(S)和均匀度(EH)对志愿者肠道微生物多样性进行分析,对图谱中具有代表性的共性和特异性条带进行胶回收和克隆测序以分析志愿者肠道微生物组成。基于PCR技术在种水平上对城乡志愿者肠道内乳杆菌属和双歧杆菌属多样性进行定性分析。【结果】相似性分析显示,城乡青年居民间肠道微生物群落结构存在分开趋势,相似性小于城市或乡村青年居民内部;多样性分析显示,城乡青年居民肠道微生物多样性差异不显著;测序结果表明,城乡居民肠道微生物组成在门水平上相同,但是在种属水平上存在差异。PCR定性分析显示Lactobacillus plantarum、L.casei和L.salivarius在哈尔滨城乡青年居民肠道内检出率接近100%,Bifidobacterium longum和B.breve的检测率约90%,在哈尔滨城乡青年居民肠道内普遍存在;乳杆菌属和双歧杆菌属各细菌种在城乡居民肠道中的检出频率差异不显著。【结论】哈尔滨城市和乡村青年居民肠道微生物多样性差异不显著。     

海鲍分离微生物Acinetobacter sp.酯酶基因的表达和酶学性质

【目的】克隆源于海鲍内脏中一株不动杆菌Acinetobacter sp.的酯酶基因estA,并对其进行重组表达和性质研究。【方法】利用分子生物学技术克隆出酯酶基因estA并构建pPICZα-C-estA重组表达载体,并通过电转化方法将重组质粒转入毕赤酵母X33中;通过甲醇诱导培养重组菌获得重组酯酶,并对重组酯酶进行生化表征。【结果】克隆得到的estA基因序列全长912 bp,编码304个氨基酸;重组X33发酵上清液中酯酶酶活力达到1 200 U/L,重组酯酶的分子量约为33.7 kD;酶学性质研究表明重组酯酶催化底物对硝基苯乙酸乙酯水解反应的最适pH和温度为8.0和40?C,在pH 8.0-10.0温度及小于60?C时具有较好的稳定性。【结论】成功克隆了海洋来源的不动杆菌酯酶基因并在Pichia pastoris中实现了高效表达。     

全域旅游发展背景下旅游用地概念及分类——社会生态系统视角

随着全域旅游的实施,旅游用地的内涵和外延在不断拓展,旅游用地的综合性、复合性、多效益性以及空间分布的叠加性日益增强。传统的旅游用地概念内涵不清,分类支离破碎,过分强调功能,缺乏系统时空结构的阐述,导致旅游用地规划难以与其他规划相协调,资源可持续利用和区域整合发展受阻,旅游用地概念和分类面临严峻挑战。在分析旅游用地概念及分类现状,探讨存在的弊端和问题的基础上,基于旅游用地社会生态系统时空结构分析对全域旅游背景下旅游用地进行了概念界定和分类。设旅游用地为一级类,下设资源系统用地、用户系统用地、基底系统用地、相互联系用地4个二级类,资源管理用地等20个三级类用地和地文景观用地等53个四级类。并对全域旅游背景下旅游用地的概念及分类进行了讨论,认为:社会生态系统理念涵盖了全域旅游的全部内涵,重视系统的层级、结构、功能、演进和相互联系,利于构建不同时空阶段的旅游用地类型的用地结构标准,促进旅游用地的规范化、分类化管理,旅游用地的时序化和动态化预测和引导;重视生态功能和社会效益,有利于旅游用地生态环境质量和综合效益的提升;涵盖核心景区及外围要素,有利于解决景区与社区的矛盾,促进全域旅游的开展和区域可持续发展;强调旅游用地的复合性、综合性,有利于旅游规划与其他规划的融合。     

库布齐东段不同植被恢复阶段荒漠生态系统碳氮储量及分配格局

为科学评价植被恢复促进沙漠化逆转对碳氮储量的影响,以流动沙地、半固定沙地、油蒿固定沙地、柠条固定沙地、沙柳固定沙地5个阶段荒漠生态系统为研究对象,采用时空替代法分析植被恢复过程中荒漠生态系统碳氮储量及分配格局。结果表明:不同恢复阶段碳氮储量均表现为:流动沙地(3320.97 kg C/hm~2、346.69 kg N/hm~2)半固定沙地(4371.46 kg C/hm~2、435.95 kg N/hm~2)油蒿固定沙地(6096.50 kg C/hm~2、513.76 kg N/hm~2)柠条固定沙地(9556.80 kg C/hm~2、926.31 kg N/hm~2)沙柳固定沙地(19488.54 kg C/hm~2、982.11 kg N/hm~2)。植被层碳氮储量均呈现随植被恢复逐渐增加的趋势,除流动沙地外,其他阶段碳氮储量均以灌木层为主,占比分别为66.65%—91.41%和52.94%—93.39%,草本和凋落物占比较小。灌木各器官生物量及碳储量分配均为:茎根叶,氮储量分配无明显规律,草本各器官生物量及碳氮储量分配均为地上部分高于地下部分。土壤层是荒漠生态系统碳氮储量的主体,碳储量占比为68.64%—99.62%,氮储量占比为89.26%—99.89%,同样呈现随植被恢复逐渐增加的趋势。碳氮储量随土层加深逐渐降低,具有明显的表层富集特征,且随植被恢复过程富集性显著加强。这说明人工建植促进植被演替实现沙漠化逆转可以显著增强荒漠生态系统的碳氮固存能力。     

我国苏云金杆菌研究60年

综述了我国近60年来的苏云金杆菌研究进展,包括资源收集及分类鉴定、Bt新基因的发掘及组学研究、病理学与作用机制、毒力测定、产品标准化、产业化,并就Bt生物农药存在的问题及改善途径进行了探讨。     

长链非编码RNA LINC00885在人食管癌细胞中的作用研究

探讨长链非编码RNA LINC00885对人食管癌细胞EC109增殖、迁移与侵袭的影响。构建LINC00885基因过表达质粒（pcDNA3.1-LINC00885）和shRNA敲低质粒（pLKO.1-LINC00885）。分别采用集落形成实验检测EC109细胞增殖能力;划痕实验检测EC109细胞横向迁移能力;Transwell实验检测EC109细胞纵向迁移能力及侵袭能力;流式实验检测LINC00885对于细胞周期的调控;实时定量PCR方法检测LINC00885 mRNA转录水平;Western blot检测BMP7及上皮间充质转化（epithelial-to-mesenchymal transition,EMT）通路相关蛋白（VIMENTIN、β-catenim和ZO-1）表达水平。在过表达LINC00885的EC109细胞中,细胞的增殖能力、迁移能力及侵袭能力均显著增强,BMP7蛋白表达升高;而在敲低表达LINC00885的EC109细胞中,细胞的增殖能力、迁移能力与侵袭能力均显著降低,BMP7蛋白表达也随之降低。另外,在过表达LINC00885的EC109细胞中,EMT通路蛋白VI...     

铜绿假单胞菌生防菌株抑菌代谢产物及其生防应用研究进展

微生物次生代谢产物的研究对开发微生物源农药具有重要意义。近年来一系列根际来源的铜绿假单胞菌被分离和鉴定,因其产生抑菌次生代谢产物,具有很好的生物防治效果。本文将系统综述铜绿假单胞菌生防菌株的种类及其抑菌代谢产物的多样性,并进一步介绍铜绿假单胞菌生防菌株的抑菌代谢产物合成机制及其遗传改造,简要讨论铜绿假单胞菌生防菌株抑菌代谢产物在生物防治上的应用和前景。     

Site Variation in Littoral Periphyton Populations: Correlation and Regression with Environmental Factors

Over a six month period, littoral periphyton communities on vertically oriented glass slides were quantitatively sampled from four stations in Elk Lake, British Columbia. Correlation and multiple regression analyses were employed to assess the temporal interrelationships between 15 environmental variables, concurrently measured, and the periphyton populations, expressed as total cell counts and species diversity, for the complete data set of each station. At all stations there was a statistically significant increase in total cell populations with increasing length of slide exposure; positive correlations also occurred with pH, temperature, nitrite, nitrate and copper, while negative ones occurred with oxygen, orthophosphate and hardness (magnesium and total). At all but one station there was a significant decrease in species diversity with increasing slide exposure duration, a decrease attributed to the simultaneous increase in standing crop resulting in intensified competition for diminishing substrate area suitable for cell colonization. Multiple stepwise regression analyses demonstrated that greater than 80% of the variation in periphyton total cells at all four stations could be reliably predicted or described in terms of length of slide exposure, phosphate (ortho and total), and hardness (calcium and total). On the other hand, exposure duration and total cell populations were the most important variables associated with changes in species diversity at three of the four stations. In general, correlations and regressions between standing crop and environmental variables were more statistically reliable and consistent between stations than comparable analyses with species diversity. Use of multiple regression and correlation disclosed the importance of small, non statistically significant variation in ecologically relevant variables and permitted objective comparison of stations.