模拟酸雨对污泥堆肥中重金属形态转化及其环境行为的影响

通过模拟酸雨淋溶土柱的方法,研究了酸雨（pH=5．0和2．9）作用下污泥堆肥中Zn、Cu和Ni的溶出和迁移性。分析了酸雨对重金属形态分布规律的影响。结果表明,在相同酸雨强度下,淋出液中重金属含量与其在土柱中迁移距离大小次序为Zn〉Cu〉Ni;重金属在相同深度的土层中含量大小次序为Zn〉Ni〉Cu。淋溶液pH的降低和污泥堆肥施加比例的提高均会增加重金属在淋出液和土柱中的含量,但不影响重金属在土柱中的迁移距离。土壤酸化会促使土壤中重金属形态向活性形态转化,而且迁移距离增加。     

pH-responsive sulfonamide/PEI system for tumor specific gene delivery: an in vitro study

The feasibility of pH-sensitive polymeric nanoparticles that effectively target the acidic extracellular matrix of tumors is demonstrated. Plasmid DNA was complexed with polyethyleneimine (PEI) and further with a pH-sensitive diblock copolymer, poly(methacryloyl sulfadimethoxine) (PSD)-block-PEG (PSD-b-PEG), to obtain naonparticles. The shielding/deshielding of nanoparticles was tested along with cell viability and transfection efficiency at physiological and tumor pH. The nanoparticles composed of DNA/PEI/PSD-b-PEG were 300 nm in size and showed low cytotoxicity and transfection at pH 7.4 due to shielding of PEI by PSD-b-PEG. The PSD-b-PEG bound to PEI/DNA complex decreased the interaction of PEI positive charges with cells and reduced the cytotoxicity by 60%. At pH 6.6, the nanoparticles demonstrated high cytotoxicity and transfection, indicating PSD-b-PEG detachment from the nanoparticles and permit PEI to interact with cells. PSD-b-PEG is able to discern the small difference in pH between normal and tumor tissues and hence has remarkable potential in drug targeting to tumor areas.     

Design, synthesis and bioevaluation of dihydropyrazolo[3,4-b]pyridine and benzo[4,5]imidazo[1,2-a]pyrimidine compounds as dual KSP and Aurora-A kinase inhibitors for anti-cancer agents

Four series of dihydropyrazolo[3,4-b]pyridines and benzo[4,5]imidazo[1,2-a]pyrimidines were designed and synthesized as dual KSP and Aurora-A kinase inhibitors for anti-cancer agents by introducing some fragments of Aurora-A kinase inhibitors into our KSP inhibitor CPUYL064. A total of 19 target compounds were evaluated by two related enzyme inhibition assays and a cytotoxicity assay in vitro. The results showed that some target compounds could inhibit both enzymes, and several of them showed significant inhibition activity against HCT116 cell line. Despite showing moderate KSP and Aurora-A kinase inhibition, the lead compounds 6a and 6e displayed significant cytotoxic activity in the micromolar range, especially against the HCT116 cell line and HepG2 cell line. The results may be useful for developing a new class of inhibitors having a dual function, KSP inhibition and Aurora-A kinase inhibition, for the treatment of cancer.     

Pretreatment with interferon-γ protects microglia from oxidative stress via up-regulation of Mn-SOD

Microglial cells, resident macrophage-like immune cells in the brain, are exposed to intense oxidative stress under various pathophysiological conditions. For self-defense against oxidative injuries, microglial cells must be equipped with antioxidative mechanisms. In this study, we investigated the regulation of antioxidant enzyme systems in microglial cells by interferon-γ (IFN-γ) and found that pretreatment with IFN-γ for 20 h protected microglial cells from the toxicity of various reactive species such as hydrogen peroxide (H₂O₂), superoxide anion, 4-hydroxy-2(E)-nonenal, and peroxynitrite. The cytoprotective effect of IFN-γ pretreatment was abolished by the protein synthesis inhibitor cycloheximide. In addition, treatment of microglial cells with both IFN-γ and H₂O₂ together did not protect them from the H₂O₂-evoked toxicity. These results imply that protein synthesis is required for the protection by IFN-γ. Among various antioxidant enzymes such as manganese or copper/zinc superoxide dismutase (Mn-SOD or Cu/Zn-SOD), catalase, and glutathione peroxidase (GPx), only Mn-SOD was up-regulated in IFN-γ-pretreated microglial cells. Transfection with siRNA of Mn-SOD abolished both up-regulation of Mn-SOD expression and protection from H₂O₂ toxicity by IFN-γ pretreatment. Furthermore, whereas the activities of Mn-SOD and catalase were up-regulated by IFN-γ pretreatment, those of Cu/Zn-SOD and GPx were not. These results indicate that IFN-γ pretreatment protects microglial cells from oxidative stress via selective up-regulation of the level of Mn-SOD and activity of Mn-SOD and catalase.     

表面展示表达植酸酶的重组酿酒酵母构建及酒精发酵

以淀粉为原料的同步糖化发酵是目前乙醇生产的主要途径之一。然而原料中含有的植酸不仅影响酒精发酵效率,而且也会导致环境中难以被植物吸收的磷含量的增加,加剧环境污染。将来源于大肠杆菌的植酸酶基因与酵母编码α-凝集素C端编码序列连接并置于α-因子分泌信号肽下游,构建植酸酶表面展示表达重组载体pMGK-AG-phy并转化工业酿酒酵母,成功获得了在细胞表面锚定表达植酸酶的重组菌PHY。重组酵母的植酸酶表达水平达到6.4 U/g(菌体湿重),其最适温度为55℃,最适pH 4.0,在pH 3.5–4.5范围内具有较高的活性。以玉米粉为原料的同步糖化发酵实验表明,重组酵母PHY的生长速度高于出发菌株,同时酒精产量相较于出发菌株提高了3.7%。更为重要的是发酵后酒糟中植酸磷含量与对照相比降低了91%。构建的表面展示表达植酸酶的重组工业酿酒酵母能够有效降低植酸含量,提高了酒糟的利用价值,减少磷排放,对燃料酒精的环境友好生产具有重要的借鉴意义。     

Effects of AM Inoculation and Organic Amendment, Alone or in Combination, on Growth, P Nutrition, and Heavy-Metal Uptake of Tobacco in Pb-Cd-Contaminated Soil

As toxic pollutants commonly found in tobacco (Nicotiana tabacum L.) products, lead (Pb) and cadmium (Cd) can enter the human body via smoking and thus pose a potential health risk to smokers. We conducted a greenhouse experiment to study the effects of arbuscular mycorrhizal (AM) inoculation with Glomus intraradices BEG 141 and organic amendment with cattle manure, alone or in combination, on the growth, P nutrition, and heavy-metal uptake by tobacco plants grown in soil to which was added Pb-Cd at 0/0, 350/1, 500/10, and 1,000/100?mg?kg^?1, respectively. In general, AM colonization and plant growth were greatly reduced by Pb-Cd contamination, whereas organic amendment alleviated Pb-Cd stress and showed some beneficial effects on AM symbiosis and some soil parameters. AM inoculation, alone or in combination with organic amendment, increased plant dry weights and improved P nutrition significantly at all Pb-Cd addition levels, and, in most cases, it decreased Pb and Cd concentrations in tobacco plants and DTPA-extractable concentrations in soil. AM inoculation increased total glomalin-related soil protein (GRSP) concentrations in soil to which Pb-Cd was added. The higher soil pH and GRSP contents and the lower DTPA-extractable Pb and Cd concentrations contributed by AM inoculation and/or organic amendment may be contributing factors that lead to higher growth promotion and lower metal toxicity and uptake by plants. Our findings suggest that AM inoculation in combination with organic manure may be a potential method for not only tobacco production but phytostabilization of Pb-Cd-contaminated soil.     

Nucleotide polymorphism and molecular evolution of the LRR region in potato late blight resistance gene Rpi-blb2

Rpi-blb2, which is originally derived from Solanum bulbocastanum, is a broad-spectrum potato late blight resistance gene and belongs to the NBS-LRR family. Here, the LRR homologues of Rpi-blb2 were cloned with PCR method from 40 potato cultivars (including 20 resistant potato cultivars and 20 susceptible ones) and 7 wild potato populations. Then, the similarities of the sequences, polymorphic (segregating) sites, and nucleotide diversities were estimated by bioinformatic methods. The results showed that high nucleotide polymorphism and some hot-spot mutations existed in the LRR region of Rpi-blb2. The test of Ka/Ks ratio showed that the function of LRR was conserved because of the purifying selection, although different positions of the Rpi-blb2 LRR region were under different selection pressures. Moreover, the LRR region of Rpi-blb2 had no clear differentiation between the cultivated and wild potatoes.     

Persistence of caliciviruses in artificially contaminated oysters during depuration

The fate of calicivirus in oysters in a 10-day depuration was assessed. The norovirus gene was persistently detected from artificially contaminated oysters during the depuration, whereas feline calicivirus in oysters was promptly eliminated. The prolonged observation of norovirus in oysters implies the existence of a selective retention mechanism for norovirus within oysters.     

Single actomyosin motor interactions in skeletal muscle

We present a study of intramuscular motion during contraction of skeletal muscle myofibrils. Myofibrillar actin was labeled with fluorescent dye so that the ratio of fluorescently labeled to unlabeled protein was 1:10⁵. Such sparse labeling assured that there was on average only one actin-marker present in the focus at a given time. From the intensity signal in the two orthogonal detection channels, significant fluctuations, similar to fluorescent burst in diffusion-based single-molecule detection schemes, were identified via a threshold algorithm and analyzed with respect to their intensity and polarization. When only rigor complexes were formed, the fluctuations of polarized intensity were characterized by unimodal Gaussian photon distributions. During contraction, in contrast, bimodal Gaussian photon distributions were observed above the rigor background threshold. This suggests that the bimodal Gaussian photon distributions represent pre- and post-power stroke conformations. Clusters of polarized photons indicated an anisotropy decay of single actomyosin motors of ~ 9 s during muscle contraction.     

钙处理对中华猕猴桃果实后熟过程的影响

研究了采后钙处理对中华猕猴桃果实的还原性Vc、还原糖、蛋白质及半乳精醛酸酶（PG）活性的影响。果实采后钙处理,能抑制PG酶的活性,延缓果实的衰老,同时保持果实的良好品质。利用中华猕猴桃对钙处理的适宜浓度范围较大的特性,可根据市场不同时期的需求采用不同浓度的钙处理。