2D and 3D sulfate-water supramolecular networks templated via triazole-nickel(II) complexes

Tuning the substituents of triazoles, we obtained di- and tri-nuclearic triazole-nickel complexes [Ni₂(deatrz)₄(H₂O)₅](SO₄)₂ · 7H₂O (1) and [Ni₃(dmtrz)₆(H₂O)₆](SO₄)₃ · 21H₂O (2) (deatrz = 3,5-diethanyl-4-amino-1,2,4-triazole; dmtrz = 3,5-dimethanyl-1,2,4-triazole). The X-ray single-crystal diffraction results reveal that sulfate anions and water clusters form supramolecular networks in both complexes. In 1, a supramolecular two-dimensional structure was fabricated by nano-sized grid with novel tetramer water rings templated via binuclear-nickel(II) cations, while in 2, water molecules and sulfate anions construct the first sulfate-water three-dimensional supramolecular network as host to encapsulate trinuclear-nickel guests.     

泡桐属七种植物的RAPD分析

利用 1 3个 1 0 mer的随机引物对中国泡桐属的 7个种进行了 RAPD分析 ,对扩增形成的谱带进行了对比 ,发现 7个种间存在较丰富的多态性带纹。经用 UPGMA法聚类结果说明可把研究的 7个种分成 2个类群。其中白花泡桐与川泡桐亲缘关系最近 ,二者与揪叶泡桐、南方泡桐、山明泡桐归为 1个类群。毛泡桐与兰考泡桐亲缘关系也较近 ,二者在系统演化上比较原始 ,归为 1个类群。     

产鼠李糖脂生物表面活性剂大肠杆菌的构建与优化

目前鼠李糖脂生物表面活性剂主要由条件致病的铜绿假单胞菌生产获得,从而影响工业应用。为了开发一种相对安全的鼠李糖脂生产菌,将带有不同强度组成型合成启动子的鼠李糖基转移酶基因(Rhamnosyltransferase gene,rhl AB)以单、中、高3种拷贝数分别在大肠杆菌ATCC 8739中异源表达,实现了不同产量的鼠李糖脂异源合成。对rhl AB基因和rha BDAC基因簇(TDP-L-鼠李糖合成的基因簇)进一步利用合成启动子进行组合调控,筛选获得了最优生产鼠李糖脂工程菌——大肠杆菌TIB-RAB226。对大肠杆菌TIB-RAB226进行发酵温度优化,鼠李糖脂产量达到124.3 mg/L,是优化前的1.17倍。通过分批补料发酵,12h时鼠李糖脂产量达到209.2 mg/L。对发酵产物进行高效液相色谱-质谱联用技术分析,共检出相对含量变化的5类质核比不同的鼠李糖脂同系物。本研究可为异源合成产鼠李糖脂提供重要参考。     

模糊聚类法在小翅雏蝗种群动态分析中的应用

1　引　　言小翅雏蝗 (Ｃｈｏｒｔｈｉｐｐｕｓｆａｌｌａｘ)是我国北方草地蝗虫的优势种之一 ,主要分布在我国的内蒙古、新疆、宁夏、甘肃、青海、河北、山西、陕西等省区及国外的西伯利亚、哈萨克斯坦、蒙古等地[7,8,10 ,12 ,13 ,16] .刘长仲等[11] 对小翅雏蝗的生物学特性进行了研究 ,李鸿昌等[9] 研究了小翅雏蝗的取食行为 ,冯光翰等[1,2 ] 提出了小翅雏蝗的防治指标 ,康乐[3～ 6] 、邱星辉[5] 、颜忠诚等[17] 研究了内蒙古典型草原小翅雏蝗的时空异质性、营养生态位以及形态特征与扩散能力之间的关系 .本文依据甘肃省夏河县甘加高山草…     

<Emphasis Type="Italic">bac</Emphasis> genes for recombinant bacilysin and anticapsin production in <Emphasis Type="Italic">Bacillus</Emphasis> host strains

The genes encoding the biosynthesis of the dipeptide bacilysin and its antibiotic constituent anticapsin were isolated from several strains of Bacillus subtilis as well as B. amyloliquefaciens and B. pumilus. The ywfBCDEF genes of B. subtilis 168 were shown to carry the biosynthetic core functions and were renamed bacABCDE. Mutation of the bacD gene or transformation of the bacABC genes into a B. subtilis (ywfA-bacABCDE) deletion mutant led to the accumulation of anticapsin, which was fourfold higher after transformation of the bacABC genes into a bacD mutant. The genes bacD and bacE proved to encode the functions of amino acid ligation and self-protection to bacilysin, respectively. Amplification of the bacABCDE gene cluster in a bacAB gene-deficient host strain of B. amyloliquefaciens resulted in a tenfold bacilysin overproduction. Some host strains required distinct glucosamine and yeast extract supplements in order to prevent suicidal effects of the recombinant antibiotic production. The bac genes from different Bacillus species revealed the same arrangement and 72.6–88.6% of sequence identity.     

Fire frequency and time‐since‐fire effects on the open‐forest and woodland flora of Girraween National Park,south‐east Queensland,Australia

Abstract The effects of recent fire frequency and time‐since‐fire on plant community composition and species abundance in open‐forest and woodland vegetation in Girraween National Park, south‐east Queensland, Australia, were examined. Cover‐abundance data were collected for shrub and vine species in at least 10 400‐m² plots in each of four study areas. Study areas were within one community type and had burnt most recently either 4 or 9 years previously. Variations in fire frequency allowed us to compare areas that had burnt at least three times in the previous 25 years with less frequently burnt areas, and also woodlands that had experienced a 28‐year interfire interval with more frequently burnt areas. Although species richness did not differ significantly with either time‐since‐fire or fire frequency, both these factors affected community composition, fire frequency being the more powerful. Moisture availability also influenced floristics. Of the 67 species found in five or more plots, six were significantly associated with time‐since‐fire, whereas 11 showed a significant difference between more and less frequently burnt plots in each of the two fire‐frequency variables. Most species, however, did not vary in cover‐abundance with the fire regime parameters examined. Even those species that showed a marked drop in cover‐abundance when exposed to a particular fire regime generally maintained some presence in the community. Five species with the capacity to resprout after fire were considered potentially at risk of local extinction under regimes of frequent fire, whereas two species were relatively uncommon in long‐unburnt areas. Variable fire regimes, which include interfire intervals of at least 15 years, could be necessary for the continuity of all species in the community.     

Metabolic regulation of citrate and iron by aconitases: role of iron–sulfur cluster biogenesis

Iron and citrate are essential for the metabolism of most organisms, and regulation of iron and citrate biology at both the cellular and systemic levels is critical for normal physiology and survival. Mitochondrial and cytosolic aconitases catalyze the interconversion of citrate and isocitrate, and aconitase activities are affected by iron levels, oxidative stress and by the status of the Fe–S cluster biogenesis apparatus. Assembly and disassembly of Fe–S clusters is a key process not only in regulating the enzymatic activity of mitochondrial aconitase in the citric acid cycle, but also in controlling the iron sensing and RNA binding activities of cytosolic aconitase (also known as iron regulatory protein IRP1). This review discusses the central role of aconitases in intermediary metabolism and explores how iron homeostasis and Fe–S cluster biogenesis regulate the Fe–S cluster switch and modulate intracellular citrate flux.     

Site-specific transfer of an intact beta-globin gene cluster through a new targeting vector

The ideal gene-therapy vector for treating genetic disorders should deliver intact therapeutic genes and their essential regulatory elements into the specific "safe genomic site" and realize long-term, self-regulatory expression. For beta-thalassemia gene therapy, viral vectors have been broadly used, but the accompanying insertional mutation and immunogenicity remain problematic. Hence, we aimed to develop new non-viral vectors that are efficient and safe in treating diseases. As previous studies have demonstrated that physiological expression of beta-globin genes requires both a 5' locus control region and 3' specific elements, we constructed a new human chromosome-derived targeting vector to transfer the intact beta-globin gene cluster into K562 cells. The whole beta-globin gene cluster was precisely integrated into the target site and expressed in a self-regulatory pattern. The results proved that the human chromosome-derived vector was specifically targeted to the human genome and this could provide a novel platform for further gene therapy research.