THREE NEW SPECIES OF THE GENUS IREPACMA FROM SHAANXI PROVINCE (LEPIDOPTERA: OECOPHORIDAE)

Abstract In this paper, the genus Zrepacma is reported for the first time from China; three new species from Shaanxi Province are described: Irepacm grandis sp. nov., Irepacma furuimacularis sp. nov. and Irepacma pallidia sp. nov., The genitalia of both sexes are illustrated.     

华东稻麦轮作生态系统的N2O排放研究

根据对华东稻麦轮作周期的N₂O排放及其影响因子的连续观测结果,分析了N₂O排放时间变化以及施肥、灌溉、温度、土壤湿度和土壤速效N素含量对N₂O排放的影响,同时还比较分析了稻田N₂O和CH₄排放.研究结果表明,稻麦轮作周期内,水稻生长季的N₂O排放量仅占30%,稻田持续淹水可比常规灌溉增加CH₄排放量26%,减少N₂O排放量11～26%.     

Biphasic transitions of a hairpin hexanucleotide triplex DNA

The conformational transitions (helix-coil transitions) of three hairpin triple helices, models 5'-(A-G)(3) + 5'-(T-C)(3)-T(4)-((br)C-T)(3) [CY], 5'-(A-G)(3) + 5'-(T-(br)C)(3)-T(4)-(C-T)(3) [YC] and 5'-(A-G)(3) + 5'-(T-(br)C)(3)-T(4)-((br)C-T)(3) [YY], are characterized in this work by UV spectroscopy. Melting of these triplexes is biphasic, and the profiles are used to obtain the thermodynamic parameters. The thermodynamic properties of the hairpin triplex are T(m) = 19.45 degrees C and DeltaH(vH) = 293.12 kJ mol(-1) for CY, T(m) = 22.85 degrees C and DeltaH(vH) = 256.63 kJ mol(-1) for YC and T(m) = 28.47 degrees C and DeltaH(vH) = 234.68 kJ mol(-1) for YY at pH 4.4. Those of the duplex are T(m) = 30.50 degrees C and DeltaH(vH) = 427.09 kJ mol(-1) for CY, T(m) = 32.96 degrees C and DeltaH(vH) = 374.47 kJ mol(-1) for YC and T(m) = 33.24 degrees C and DeltaH(vH) = 329.67 kJ mol(-1) for YY at pH 4.4. The distinct transitions of triplex to duplex and duplex to single strands are analyzed using the nearest-neighbor Ising model. Electrostatic effects on each conformation are also analyzed.     

哺乳类细胞基因表达系统

真核基因的转录和转译调控是哺乳类细胞基因表达系统建立和发展的基础,外源基因的表达水平不仅决定于启动子/增强子的强弱,还与剪接信号、终止信号和poly(A)信号以及质粒的拷贝数等因素有关。另外,在基因治疗的研究中,也已寻找到多种具有组织或肿瘤特异性的启动子,来达到特异性肿瘤基因治疗的目的。     

双色FISH和DNA纤维FISH方法的建立与应用

在构建了含毛细胞白血病相关的结构性倒位inv (5) (p13.1q13.3)的细胞系后,为了确定该新建细胞系在建株过程中其倒位断裂点关键区遗传物质是否发生改变,以生物素或地高辛标记的cCI5-216 和cCI5-267黏粒DNA为探针,进行染色体中期、间期和DNA纤维3种双色荧光原位杂交的分析。结果表明：该新建细胞系的3种双色荧光原位杂交结果,均与该细胞系的原代细胞的完全相同,证实了该细胞系倒位断裂点关键区的遗传物质结构未发生改变。该细胞系是揭示毛细胞白血病发病的分子机理的重要研究材料。     

Biotin-ubiquitin tagging of mammalian proteins in Escherichia coli

Ubiquitin has been used in protein expression for enhancing yields and biological activities of recombinant proteins. Biotin binds tightly and specifically to avidin and has been widely utilized as a tag for protein purification and monitoring. Here, we report a versatile system that takes the advantages of both biotin and ubiquitin for protein expression, purification, and monitoring. The tripartite system contained coding sequences for a leader biotinylation peptide, ubiquitin, and biotin holoenzyme synthetase in two reading frames under the control of T7 promoter. The expression and purification of several large mammalian enzymes as biotin-ubiquitin fusions were accomplished including human ubiquitin activating enzyme, SUMO activating enzymes, and aspartyl-tRNA synthetase. Expressed proteins were purified by one-step affinity column chromatography on monomeric avidin columns and purified proteins exhibited active function. Additionally, the ubiquitin protein hydrolase UBP41, expressed and purified as biotin-UBP41, efficiently and specifically cleaved off the biotin-ubiquitin tag from biotin-ubiquitin fusions to produce unmodified proteins. The present expression system should be useful for the expression, purification, and functional characterization of mammalian proteins and the construction of protein microarrays.