Targeting of gene expression by siRNA in CML primary cells

Development of array methods contributes to elucidation of many genes expressed during oncogenesis. Our array-based analyses of gene expression in patients with chronic myeloid leukemia (CML) revealed several genes (MMP8, MMP9, PCNA, JNK2, MAPK p38) with significant increased expression. We suppose that the genes may be implicated in the disease development and a siRNA-suppression can elucidate their functions in leukemogenesis. One of the crucial requirements for this purpose is a high efficiency of siRNA delivery into CML primary cells. Using fluorescein-labeled siRNAs we systematically tested a variety of physical and chemical non-vector based transfection methods in order to evaluate which of them gave the most suitable transfer. Chemically synthesized siRNAs against mentioned genes were transfected into the cells and level of knockdown was determined by real time RT-PCR. Chemical transfection reagents (Oligofectamine, Metafectene, siPORT Amine) commonly used to transfect siRNAs in CML cell lines showed very low siRNA delivery in CML primary cells—mRNA levels decreased at the most to 76%. Electroporation achieved better results (suppression to 63%) but it was associated with high degree of cell death (more than 60%). In the study we obtained the best transfection efficiency using nucleofector technology. Gene expressions ranged 22–37% that remained from original levels. According to our results, nucleofection appears to be the only suitable non-viral method for siRNA delivery into the hard-to-transfect CML primary cells.     

Magnetic field induced residual dipolar couplings of imino groups in nucleic acids from measurements at a single magnetic field

For base-paired nucleic acids, variations in ¹ J _NH and the imino ¹H chemical shift are both dominated by hydrogen bond length. In the absence of molecular alignment, the ¹ J _NH coupling for the imino proton then can be approximated by ¹ J _NH = (1.21Hz/ppm)δ_H − 103.5 ± 0.6 Hz, where δ_H represents the chemical shift of the imino proton in ppm. This relation permits imino residual dipolar couplings (RDCs) resulting from magnetic susceptibility anisotropy (MSA) to be extracted from measurement of (¹ J _NH + RDC) splittings at a single magnetic field strength. Magnetic field-induced RDCs were measured for tRNA^Val and the alignment tensor determined from magnetic-field alignment of tRNA^Val agrees well with the tensor calculated by summation of the MSA tensors of the individual nucleobases. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Jinfa Ying, Alexander Grishaev and Michael P. Latham contributed equally to this work.     

Combined application of Pseudomonas fluorescens strain LRB3W1 with a low dosage of benomyl for control of cabbage yellows caused by Fusarium oxysporum f. sp. conglutinans

An antagonistic bacterium, Pseudomonas fluorescens strain LRB3W1, inhibited the fungal growth of Fusarium oxysporum f. sp. conglutinans in vitro and suppressed cabbage yellows caused by F. oxysporum f. sp. conglutinans. Under glasshouse conditions, the bacterium survived at ca. 10⁶-10⁷ CFU g^-1 in the cabbage rhizosphere for 4 weeks after the initial application. The chemical fungicide, benomyl, did not suppress the disease severity at low concentration (1 or 10 µg mL^-1). However, the disease severity was decreased by the combined application of a low dosage of benomyl with strain LRB3W1. Combined application of a low dosage of benomyl with strain LRB3W1 was more effective than treatment with the bacterium alone. The survival of strain LRB3W1 was not influenced by the presence of benomyl. This combined use of the biocontrol agent, strain LRB3W1, and a fungicide, benomyl, should be an attractive approach for suppressing cabbage yellows in sustainable agriculture because of the reduced chemical dosages needed for disease management.     

具脉冲控制的害虫管理SI模型

这篇论文讨论了关于脉冲释放病虫与喷洒农药的害虫管理SI模型．我们不但证明了系统的所有解的一致完全有界,而且得到了害虫灭绝的边界周期解的全局渐进稳定的条件是In1/1-μ1＞rT-rμθ（1-exp（-wT））/Kw（1-（1-μ2）exp（-WT）-βμ^3（1-exp（-3WT））/3w（1-μ2）exp（-WT））^3也得到了系统（1）的一致持久的条件我们的结论为实际的害虫管理提供了可靠的理论依据．     

海绵共附生微生物的研究新进展

海绵是最原始的一类后生动物,已被作为海洋活性化合物的重要来源之一,其独特的孔状结构使其成为许多海洋微生物的优良宿主。近年来国内对海绵及其共附生微生物的研究主要集中在它们产生的活性物质方面,但对海绵共附生微生物的分布、多样性及其对宿主海绵作用的研究鲜有报道,就国内外研究进展进行了综述。     

Segment TM7 from the cytoplasmic hemi-channel from VO-H-V-ATPase includes a flexible region that has a potential role in proton translocation

A 900-MHz NMR study is reported of peptide sMTM7 that mimics the cytoplasmic proton hemi-channel domain of the seventh transmembrane segment (TM7) from subunit a of H⁺-V-ATPase from Saccharomyces cerevisiae. The peptide encompasses the amino acid residues known to actively participate in proton translocation. In addition, peptide sMTM7 contains the amino acid residues that upon mutation cause V-ATPase to become resistant against the inhibitor bafilomycin. 2D TOCSY and NOESY ¹H-¹H NMR spectra are obtained of sMTM7 dissolved in d₆-DMSO and are used to calculate the three-dimensional structure of the peptide. The NMR-based structures and corresponding dynamical features of peptide sMTM7 show that sMTM7 is composed of two α-helical regions. These regions are separated by a flexible hinge of two residues. The hinge acts as a ball-and-joint socket and both helical segments move independently with respect to one another. This movement in TM7 is suggested to cause the opening and closing of the cytoplasmic proton hemi-channel and enables proton translocation.     

女贞子化学成分、药理作用及药动学研究进展

女贞子系木犀科(Oleaceae)女贞属植物女贞(Ligustrum lucidum)的干燥果实,为我国传统中药,具有滋补肝肾、明目乌发的功效。女贞子含三萜类、环烯醚萜类、苯乙醇苷类及黄酮类等多种化学成分。许多药理作用研究表明女贞子具有抗肿瘤、抗氧化、抗炎镇痛、保肝、抗骨质疏松、免疫调节、降血糖降血脂、抗菌抗病毒等活性。对女贞子的化学成分、药理作用及药代动力学研究进行综述,以期为我国女贞子资源的进一步开发和利用提供参考。     

干旱死亡叶片与自然凋落叶化学性质对比研究

为了解干旱死亡叶片与自然凋落叶化学性质的差异性,对云南元江干热河谷5种植物(鞍叶羊蹄甲、白皮乌口树、灰毛浆果楝、细基丸和九里香)干旱死亡叶片和自然凋落叶化学性质进行比较分析。结果表明,干旱死亡叶片和自然凋落叶在碳和养分化学特性上表现出较大变异,且不同树种间存在极显著差异(P<0.001)。与自然凋落叶相比,干旱死亡叶片具有较高的可溶性碳、C/N比和Mg含量,而木质素、半纤维素和N含量则较低。干旱死亡叶片与自然凋落叶间的碳(R²=0.56,P<0.01)、纤维素(R²=0.52,P<0.01)、半纤维素(R²=0.85,P<0.001)、单宁(R²=0.99,P<0.001)、木质素/N(R²=0.60,P<0.01)、C/N(R²=0.64,P<0.001)和氮含量(R²=0.85,P<0.001)呈显著正相关。因此,可根据自然凋落叶化学性质预测未来极端干旱条件下干旱死亡叶片的化学性质。     

Chemical rescue of H+ delivery in proton transfer mutants of reaction center of photosynthetic bacteria

In the native and most mutant reaction centers of bacterial photosynthesis, the electron transfer is coupled to proton transfer and is rate limiting for the second reduction of Q_B^??→?Q_BH₂. In the presence of divalent metal ions (e.g. Cd²⁺) or in some (“proton transfer”) mutants (L210DN/M17DN or L213DN), the proton delivery to Q_B^? is made rate limiting and the properties of the proton pathway can be directly examined. We found that small weak acids and buffers in large concentrations (up to 1?M) were able to rescue the severely impaired proton transfer capability differently depending on the location of the defects: lesions at the protein surface (proton gate H126H/H128H?+?Cd²⁺), beneath the surface (M17DN?+?Cd²⁺, L210DN/M17DN) or deep inside the protein (L213DN) could be completely, partially or to very small extent recovered, respectively. Small zwitterionic acids (azide/hydrazoic acid) and buffers (tricine) proved to be highly effective rescuers consistent with their enhanced binding affinity and access to any of the proton acceptors (including Q_B^? itself) in the pathway. As a consequence, back titration of the protons at L212Glu could be observed as a pH-dependence of the rate constant of the charge recombination in the presence of azide or formate. Model calculations support the collective influence of the acid cluster on the change of the protonation states upon extension of the cluster with the bound small acid. In proton transfer mutants, the rescuing agents decreased the free energy of activation together with their enthalpic and entropic components. This is in agreement with the hypothesis that they function as protein-penetrating protonophores delivering protons into the chain and select dominating paths out of many alternate routes. We estimate that the proton delivery will be accelerated in one pathway out of 100–200 alternate pathways. The implications for design of the chemical recovery of impaired intra-protein proton transfer pathways in proton transfer mutants are discussed.     

Non-polar and polar chemical profiling of six Casearia species (Salicaceae)

Six species of Casearia (C. decandra, C. grandiflora, C. javitensis, C. arborea, C. lasiophylla and C. ulmifolia) were chemically investigated in their non-polar and polar constituents. To this purpose, leaf extracts were analyzed by Gas- (GC) and Liquid-Chromatography (LC) coupled with Mass Spectrometry (MS). Twenty compounds, mainly identified as terpenes, fatty acids and hydrocarbons, and differentially expressed in the six species, were detected in the non-polar extracts. Fourteen compounds, among which glycosylated flavonoids and clerodane-type diterpenes, were tentatively identified by LC-MS/MS analysis in the leaf ethanol extracts.