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.     

TRAIL-R2 (DR5) mediates apoptosis of synovial fibroblasts in rheumatoid arthritis

TRAIL has been proposed as an anti-inflammatory cytokine in animal models of rheumatoid arthritis (RA). Using two agonistic mAbs specific for TRAIL-R1 (DR4) and TRAIL-R2 (DR5), we examined the expression and function of these death receptors in RA synovial fibroblast cells. The synovial tissues and primary synovial fibroblast cells isolated from patients with RA, but not those isolated from patients with osteoarthritis, selectively expressed high levels of cell surface DR5 and were highly susceptible to anti-DR5 Ab (TRA-8)-mediated apoptosis. In contrast, RA synoviocytes did not show increased expression of TRAIL-R1 (DR4), nor was there any difference in expression of Fas between RA and osteoarthritis synovial cells. In vitro TRA-8 induced apoptosis of RA synovial cells and inhibited production of matrix metalloproteinases induced by pro-inflammatory cytokines. In vivo TRA-8 effectively inhibited hypercellularity of a SV40-transformed RA synovial cell line and completely prevented bone erosion and cartilage destruction induced by these cells. These results indicate that increased DR5 expression and susceptibility to DR5-mediated apoptosis are characteristic of the proliferating synovial cells in RA. As highly proliferative transformed-appearing RA synovial cells play a crucial role in bone erosion and cartilage destruction in RA, the specific targeting of DR5 on RA synovial cells with an agonistic anti-DR5 Ab may be a potential therapy for RA.     

Sphingosine kinase type 1 induces G12/13-mediated stress fiber formation,yet promotes growth and survival independent of G protein-coupled receptors

Sphingosine 1-phosphate (S1P) is the ligand for a family of specific G protein-coupled receptors (GPCRs) that regulate a wide variety of important cellular functions, including growth, survival, cytoskeletal rearrangements, and cell motility. However, whether it also has an intracellular function is still a matter of great debate. Overexpression of sphingosine kinase type 1, which generated S1P, induced extensive stress fibers and impaired formation of the Src-focal adhesion kinase signaling complex, with consequent aberrant focal adhesion turnover, leading to inhibition of cell locomotion. We have dissected biological responses dependent on intracellular S1P from those that are receptor-mediated by specifically blocking signaling of Galphaq, Galphai, Galpha12/13, and Gbetagamma subunits, the G proteins that S1P receptors (S1PRs) couple to and signal through. We found that intracellular S1P signaled "inside out" through its cell-surface receptors linked to G12/13-mediated stress fiber formation, important for cell motility. Remarkably, cell growth stimulation and suppression of apoptosis by endogenous S1P were independent of GPCRs and inside-out signaling. Using fibroblasts from embryonic mice devoid of functional S1PRs, we also demonstrated that, in contrast to exogenous S1P, intracellular S1P formed by overexpression of sphingosine kinase type 1 promoted growth and survival independent of its GPCRs. Hence, exogenous and intracellularly generated S1Ps affect cell growth and survival by divergent pathways. Our results demonstrate a receptor-independent intracellular function of S1P, reminiscent of its action in yeast cells that lack S1PRs.