水葫芦根际细菌群落结构多样性分析

【目的】了解水葫芦根际细菌群落结构。【方法】运用末端限制性片段长度多态性(Terminal restriction fragment length polymorphism,T-RFLP)技术分析富营养化水体中水葫芦根际和水葫芦近、远水样的细菌群落特征及多样性,结合克隆文库技术和培养法分析根际的细菌种群类型。【结果】同一时期水葫芦根际细菌多样性(Shannon-Weiner指数H′或Simpson指数D)更高,水葫芦近水样次之,远水样最小。10月份的细菌多样性高于5月份的。通过水葫芦根际细菌的克隆文库可知变形杆菌门(Proteobacteria)是水葫芦根际细菌的主要类群,占总群体的65.1%,包括噬菌弧菌(Bacteriovorax sp.)、Dechloromonas sp.、Leptothrix sp.、红螺菌科(Rhodospirillaceae)、Rhodoferax sp.和红环菌科(Rhodocyclaceae)等。T-RFLP图谱显示159 bp为最大优势菌,247 bp为第二大优势菌,对照克隆文库及培养结果分析247 bp属于γ-Proteobacteria,159 bp为不动杆菌(Acinetobacter sp.)。【结论】水葫芦根际细菌的群落结构丰富,不同时段水葫芦根际细菌的丰度略有变化,主要类群为变形杆菌门。     

半干旱区湿地-干草原交错带边界判定及其变化

鉴于目前国内对于半干旱区及小尺度上湿地-干草原交错带边界界定的研究较少,利用交错带对其周围环境变化具有提前指示作用的原理,以宁夏盐池四儿滩湿地为例,首先探讨游动分割窗技术在半干旱区湿地-干草原交错带边界判定中的可行性,其次再对2006年—2010年湿地-干草原交错带的宽度和边界进行判定,通过交错带的宽度和边界变化并结合交错带内植被的变化情况,综合对整个湿地生态系统的健康状况和湿地退化进行研究。结果表明:研究的尺度大小以及交错带过渡性是否明显将决定适宜窗口宽度的大小,这点在选择最小适宜窗口宽度时体现更为显著;降雨量是决定该区交错带的位置与宽度的最主要因素,但降雨量并不是决定该区交错带内植被变化状况的最主要因素,交错带距湿地核心区的距离是影响交错带内物种丰富度指数变化的最主要因素;由于保护区的成立,四儿滩湿地在2006年—2007年间,交错带宽度变大,湿地状况转好,2008年—2010年,由于铁路建设,湿地遭到破坏,交错带萎缩,湿地出现退化现象。湿地-干草原交错带作为一个敏感地带,它的变化情况可以对整个湿地生态系统的变化情况作出一定的提前预示;在半干旱区湿地的健康评价和退化研究中,通过交错带的变化来反映整个湿地生态系统的健康情况是一种可行的思路和方法。     

不同细胞周期大鼠肝实质细胞癌细胞粘弹特性研究

以胸腺嘧啶核苷和秋水仙碱顺序阻断法及胸腺嘧啶核苷双阻断法分别获得同步化Ｇ１期和Ｓ期细胞,从细胞周期角度出发,采用微管吸吮技术对大鼠肝实质细胞癌细胞的粘弹特性进行了测定并以标准线性固体模型对实验数据进行了拟合,结果表明：该细胞具有高弹性和低粘性的总体特征;Ｇ１期细胞与Ｓ期细胞相比具有高Ｋ１值和低μ值的特点,从而显示Ｇ１期细胞比Ｓ期细胞具有更大的强度和更快的被动变形能力。这些结果不仅反映了同步化细胞存在的细胞骨架状态的周期性差异,也提示Ｇ１期细胞可能比Ｓ期细胞更适于在血流中存活和转移。     

N-glycan structures of a recombinant mouse soluble Fcγ receptor II

N-glycans of a recombinant mouse soluble Fc receptor II (sFcRII) expressed in baby hamster kidney cells were released from glycopeptides by digestion with glycoamidase A (from sweet almond), and the reducing ends of the oligosaccharides were reductively aminated with 2-aminopyridine. The derivatized N-glycans were separated and structurally identified by a three-dimensional high-performance liquid chromatography (HPLC) mapping technique on three kinds of HPLC columns [Takahashi, et al. (1995) Anal. Biochem. 226: 139–46]. Eighteen different major N-glycan structures were identified, of which six were neutral (45%), five mono-sialyl (49%), one di-sialyl (4.6%), five tri-sialyl (1.1%), and one tetra-sialyl (0.3%). All N-glycan structures determined were complex type with fucosylation at the N-acetylglucosamine residue of the reducing end, and N-acetylneuraminic acid, when present, was -(2,3)-linked. The existence of a unique structure containing both N-acetylgalactosamine and -(2,3)-N-acetylneuraminic acid residues at the reducing ends, as below, was confirmed by MALDI-TOF mass spectrometry.     

Using 137Cs technique to quantify soil conservation capacities of different ecosystems in Wolong Natural Reserve, southwestern China

Reliable information about soil conservation capacities of different natural ecosystems is an important reference for the design of targeted erosion and sediment control strategies. The objective of this paper is to quantify the soil conservation capacities of different natural ecosystems that can represent different climatic zones. The 137Cs technique has been used to estimate soil redistribution rates in different natural ecosystems over the past 40 years in Wolong Nature Reserve. The reserve, transiting from the Chengdu plain to the Qinghai-Tibet plateau, maintains rich ecosystems from subtropical to frigid.The net soil erosion rates of 5 selected ecosystems that represent a warm coniferous-broadleaf-mixed forest, a cold-resistant deciduous taiga forest, a cold-resistant shrub, an evergreen cold-resistant taiga servation capacities are reversed in order. The reference inventories for 137Cs in different ecosystems velop effective erosion and sediment strategies in areas with similar climates should consider natural ecosystem types.     

芒果畸形病病原菌Fusarium mangiferae的快速分子检测

芒果畸形病是芒果上的重要病害之一,由镰孢菌侵染引起,其中以Fusarium mangiferae为主要致病菌.该病害诊断困难,且难于有效控制,因此,一旦发生则对芒果生产造成严重威胁.研究基于ISSR分子标记技术,从50条已知引物中筛选得到一条目的引物UBC 888,该引物可稳定扩增出大小为479bp的F. mangiferae特异性条带(GenBank Accession No. KJ526382).根据获得的特异性片段序列设计引物,成功地将ISSR标记转化为SCAR标记,并获得一对SCAR特异性引物(W342,W1772)和一段大小为1 376bp的特异性扩增片段(GenBank Accession No. KJ526383).通过优化特异性引物扩增条件,获得最适退火温度,构建芒果畸形病病原菌F. mangiferae的快速分子检测技术.此技术操作简单,特异性强,可检测真菌DNA的含量最低为10pg,适用于F. mangiferae和田间带菌芒果组织高灵敏度快速检测,为芒果畸形病的早期诊断和及时预防提供可靠理论依据和技术方法.     

Structural understanding of stabilization patterns in engineered bispecific Ig‐like antibody molecules

Bispecific immunoglobulin‐like antibodies capable of engaging multiple antigens represent a promising new class of therapeutic agents. Engineering of these molecules requires optimization of the molecular properties of one of the domain components. Here, we present a detailed crystallographic and computational characterization of the stabilization patterns in the lymphotoxin‐beta receptor (LTβR) binding Fv domain of an anti‐LTβR/anti‐TNF‐related apoptosis inducing ligand receptor‐2 (TRAIL‐R2) bispecific immunoglobulin‐like antibody. We further describe a new hierarchical structure‐guided approach toward engineering of antibody‐like molecules to enhance their thermal and chemical stability. Proteins 2009. © 2009 Wiley‐Liss, Inc.     

内蒙古天然草原不同放牧压力下亚洲小车蝗的食性及营养生态位（英文）

植物表皮蜡质中的饱和链烷作为内源指示剂广泛用于评价放牧家畜的食性和食量, 但用于天然草原蝗虫食性的评价研究较少。为了探讨天然草原蝗虫的食性及其生态位变化, 本研究以内蒙古天然草原为研究对象, 于2003年7-8月沿降水梯度选择3种典型植物群落（小针茅Stipa klemenzii、 羊草Leymus chinensis和大针茅Stipa grandis群落）, 在每个植物群落不同放牧压力下小区随机做20个植被样方, 样方内植物齐地面刈割, 测定其地上生物量和物种多样性, 取主要植物种测定其链烷模式, 同时采集放牧小区优势蝗虫种亚洲小车蝗Oedaleus asiaticus的粪便, 测定其链烷模式, 运用链烷技术评价蝗虫的食性及其营养生态位。结果表明： 不同植物群落中优势牧草种类及其比例不同, 其链烷模式存在种间差异, 链烷技术可以评价亚洲小车蝗的食性。亚洲小车蝗的食性在不同植物群落及不同放牧压力下存在显著的差异, 在羊草和大针茅群落中, 亚洲小车蝗是禾草采食者, 主要采食羊草和糙隐子草Cleistogenes squarrosa, 且与绵羊的营养生态位重叠指数较低, 分别为0.0619和0.0172; 在小针茅群落中亚洲小车蝗是杂类草采食者, 主要采食无芒隐子草Cleistogenes songorica、 猪毛菜Salsola collina和小针茅, 且与绵羊的营养生态位重叠指数较高, 达到0.1815。因此, 放牧不仅改变了群落的植物种类组成, 而且直接影响了亚洲小车蝗的食物组成, 二者对食物资源利用存在一定程度的竞争。     

Essential Oil Variability and Biological Activities of Tetraclinis articulata (Vahl) Mast. Wood According to the Extraction Time

In the present work, the hydrodistillation (HD) and microwave‐assisted hydrodistillation (MAHD) kinetics of essential oil (EO) extracted from Tetraclinis articulata (Vahl ) Mast. wood was conducted, in order to assess the impact of extraction time and technique on chemical composition and biological activities. Gas chromatography (GC) and GC/mass spectrometry analyses showed significant differences between the extracted EOs, where each family class or component presents a specific kinetic according to extraction time, technique and especially for the major components: camphene, linalool, cedrol, carvacrol and α‐acorenol. Furthermore, our findings showed a high variability for both antioxidant and anti‐inflammatory activities, where each activity has a specific effect according to extraction time and technique. The highlighted variability reflects the high impact of extraction time and technique on chemical composition and biological activities, which led to conclude that we should select EOs to be investigated carefully depending on extraction time and technique, in order to isolate the bioactive components or to have the best quality of EO in terms of biological activities and preventive effects in food.     

克隆技术引发的伦理之争

自从克隆羊多莉诞生以来,有关克隆人的伦理学争论就一直喋喋不休。世界上的各种政治组织和各国政府都明确反对生殖性克隆,而科学家们则对克隆技术的不完善心存疑虑。为了克服克隆过程中的伦理学障碍和技术缺陷,科学家们在核移植技术的基础上,又发展了异种核移植技术、诱导多能干细胞技术等。诱导的多能干细胞可以分化成各种组织,甚至能发育成个体,这些方法使克隆技术不再破坏胚胎,避免了伦理学纠纷。尽管科学技术在进步,但是人们对克隆人仍有很多不解和困惑。从自主、不伤害、行善和公正等四大生命伦理学原则着手,在技术层面上提出了尽管克隆人不会搞乱人际关系,不会减少人类基因多样性,也不会克隆出类似希特勒的战争狂人,但是,人类的生殖性克隆却剥夺了克隆人的自主性,对克隆人的生理和心理都有所伤害,违反了公正和行善的原则。因此,是否可以克隆人在伦理上仍然是需要长期讨论的问题。