气体信号分子一氧化氮和乙烯的生物学功能：一氧化氮在植物盐胁迫中的作用和乙烯激活钙离子通道

一氧化氮（NO）是重要的植物信号分子，参与许多植物生理过程。以拟南芥野生型和Atnoa1突变体为材料研究了NO在植物抗盐胁迫中的作用。 T-DNA插入AtNOA1基因的第一个外显子，使Atnoa1突变体中NOS活性大幅度下降，NO释放减少。用不同浓度的NaCl对拟南芥野生型和Atnoa1突变体进行盐胁迫处理后，Atnoa1突变体中Na+离子积累较野生型多，K+离子吸收较野生型少，从而使突变体中的Na+/K+比野生型高，对突变体造成了更大的伤害。Atnoa1突变体种子萌发和幼苗生长对盐胁迫更敏感。盐胁迫处理后，Atnoa1突变体的存活率比野生型低。无论是在正常生长条件下，还是盐胁迫条件下，Atnoa1突变体中的H2O2和TBARS含量都比野生型中高，说明Atnoa1突变体对盐胁迫和氧化胁迫都比野生型更敏感。用NOS抑制剂和NO清除剂处理拟南芥野生型，减少内源NO释放量，使其在盐胁迫条件下的Na+/K+比增高。盐胁迫处理降低了野生型体内的NOS活性，减少了NOA1蛋白的表达，DAF-2DA标记的NO荧光强度减弱。用NO供体SNP处理Atnoa1突变体，可以减少盐胁迫引起的Na+/K+比增加。以上研究结果证明NOS介导的NO合成在植物抗盐胁迫中起重要作用。 乙烯作为一种植物气体激素参与植物生长发育的许多生理生化过程。植物细胞自由钙离子（[Ca2+]c）是重要信号分子，在植物应答外界信号中起非常重要的作用。外界信号通过开启植物细胞质膜的钙离子通道，使得胞外钙离子进入细胞，导致瞬间[Ca2+]c的增加，激活钙依赖型的蛋白和蛋白激酶，从而改变生理生化过程。本研究利用膜片钳和激光共聚焦显微技术，研究了外源乙烯对烟草悬浮细胞质膜Ca2+离子通道和细胞中[Ca2+]c活性的影响。乙烯供体乙烯利和乙烯合成前体ACC能够迅速诱导内向型电流，表明这些处理能开启离子通道。通过离子替代实验和离子通道的药理学分析证实乙烯利和ACC激活了一种对Ba2+, Mg2+和Ca2+等阳离子具有通透性的离子通道，La3+、Gd3+和Al3+抑制该通道的活性。乙烯受体拮抗物（1-MPP）和ACC合成酶抑制剂，能够减弱乙烯利和ACC对这种通道的活化作用，说明乙烯利和ACC是通过乙烯活化此类Ca2+离子通道。用Ca2+敏感的荧光标记物Fluo-3标记，通过激光共聚焦显微观察，发现乙烯利能够诱导烟草悬浮细胞中[Ca2+]c离子浓度的增加，而且Gd3+和BAPTA显著抑制乙烯利诱导的细胞中[Ca2+]c离子的增加。说明外源Ca2+离子通过质膜上被激活的Ca2+离子通道进入细胞，使细胞中[Ca2+]c离子浓度增加。以上结果说明，乙烯活化质膜上的Ca2+离子通道，使细胞外Ca2+离子进入细胞，导致细胞中[Ca2+]c离子浓度增加，是乙烯信号转导途径的重要步骤。

一氧化氮（NO）在硝酸盐调节玉米根伸长中的作用

植物根系大小和形态是决定植物吸氮能力的重要因素，而植物根系生长发育与土壤中营养元素的分布及其有效性密切相关，尤其是硝酸盐。然而目前关于硝酸盐调节植物根系生长的生理机制仍不清楚。一氧化氮（NO）是一种重要的气体信号分子，参与植物体内多种生理生化过程，包括调节根的生长发育。本研究以玉米自交系478为材料，采用营养液培养法，探讨了NO在硝酸盐调节玉米根系生长中的作用。主要结果和结论如下： 玉米幼苗在不同硝酸盐水平下生长7天后，主根伸长随着硝酸盐浓度的升高而下降;与0.01 mM硝酸盐处理下的玉米主根伸长相比，0.1 mM和1 mM硝酸盐处理对玉米主根伸长分别抑制了30%和36%。随着硝酸盐浓度的增加，玉米主根根尖过氧化氢（H2O2）含量表现出降低的趋势，而抗氧化酶，如超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）的活性则表现出增加的趋势。外源供应过氧化氢对低浓度硝酸盐（0.01 mM）和高浓度硝酸盐（10 mM）处理下的玉米根伸长都没有影响，这表明了根尖过氧化氢含量的下降不是高浓度硝酸盐抑制玉米主根伸长的原因。 NO供体硝普钠（SNP）能够缓解高浓度硝酸盐对玉米主根伸长的抑制，而对低浓度硝酸盐处理下的主根伸长没有影响，而且NO清除剂亚甲基兰（MB）和NO合成酶抑制剂Nω-硝基-L-精氨酸（L-NNA）显著抑制了低浓度硝酸盐处理下的玉米主根伸长，而对高浓度硝酸盐处理下的玉米主根伸长没有影响。用NO特异性荧光染料4,5-二氨基乙酰乙酸荧光素(DAF-2DA)检测结果表明：高浓度硝酸盐显著降低玉米根尖NO含量。而玉米根中的硝酸还原酶活性随硝酸盐浓度的增加而增加。以上结果说明，高浓度硝酸盐抑制玉米主根伸长可能是与根尖NO合成酶的下调所导致的内源NO含量的降低有关。 另外，外源生长素（IAA）能缓解高浓度硝酸盐对玉米主根伸长的抑制，同时，也增加了高浓度硝酸盐处理下玉米根中内源NO含量，而对低浓度硝酸盐处理下的玉米根中内源NO没有影响。因此推测，根尖生长素的下降导致内源NO含量的降低可能是高浓度硝酸盐抑制玉米主根伸长的原因。

一氧化氮在磷酸盐调节拟南芥根系形态变化中的作用

磷缺乏已成为制约世界农业生产的重要因子。植物根系的大小和形态是决定植物吸收土壤磷能力的重要因素，而且根系的生长发育与磷素的分布及其有效性密切相关。关于磷酸盐调节植物根系生长研究已有很多报道，但其生理和分子机制仍不清楚。一氧化氮 (NO) 是一种重要的气体信号分子，参与调控植物的生长发育和对多种逆境胁迫的应答反应。本文选用拟南芥为实验材料，研究探讨了NO与缺磷诱导的拟南芥根系形态变化之间的关系，主要结果如下： 用正常磷水平 (1 mM) 和低磷水平 (1 µM) 处理拟南芥幼苗，发现低磷抑制主根伸长，刺激侧根发生。外源NO供体销普纳 (SNP) 也抑制主根、刺激侧根生长，与低磷诱导根系形态变化相似。NO清除剂c-PTIO和一氧化氮合成酶 （NOS）抑制剂L-NNA均可部分减缓由低磷引起的对主根生长的抑制和对侧根的刺激作用。暗示低磷诱导的拟南芥根系形态的变化可能与NO含量的降低有关。 利用NO荧光标记物DAF-FM和激光共聚焦显微成像技术，本研究发现缺磷6 h和24 h后根细胞内源NO含量显著增加，而且NOS 抑制剂能减少低磷诱导的根细胞NO含量的增加。与正常供磷处理相比，低磷处理6 h和24 h，拟南芥根中编码与NO合成相关的基因（AtNOA1）的表达量增加，缺磷24 h后根中NOS酶活性升高。为了明确低磷诱导的NO 增加是否与硝酸还原酶（NR）介导的NO合成有关，本论文进一步研究了低磷对拟南芥硝酸还原酶活性和编码NR基因 （AtNR1和AtNR2）表达的影响。研究发现低磷处理6 h和24 h后和AtNR1和AtNR2基因的表达均没有变化，且蛭石中生长的拟南芥缺磷1个月后NR活性也没有发生变化;拟南芥的NR双突变体nia1，nia2在低磷处理24 h后，其根中的内源NO含量表现出与野生型相同的增加。因此这些研究结果表明，缺磷后拟南芥根细胞NO的含量增加主要由于NOS的活性升高，而与NR介导的NO合成无关。 已有资料表明低磷诱导植物根细胞内源过氧化氢（H2O2）分布和含量的变化。本论文研究了低磷处理对用H2O2标记物CM-H2DCFDA标记不同磷处理下的拟南芥根中的H2O2。研究发现，缺磷6 h根中H2O2的分布无明显变化，缺磷24 h后H2O2呈斑块状分布，且多集中在根尖伸长区。缺磷24 h后，叶片中的抗氧化保护酶—超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性没有明显变化。说明缺磷24 h 后产生的H2O2没有引起氧化胁迫，而是作为一种信号分子，与NO相互作用共同介导低磷胁迫的应答反应。关于NO与H2O2在低磷诱导的根形态变化中的信号转导过程还有待进一步研究。

Antihemostatic molecules from saliva of blood-feeding arthropods

The ability to feed on vertebrate blood has evolved many times in various arthropod clades. Consequently, saliva of blood-feeding arthropods has proven to be a rich source of antihemostatic molecules. A variety of platelet aggregation inhibitors antagonize platelet responses to wound-generated signals, including ADP, thrombin, and collagen. Anticoagulants disrupt elements of both the intrinsic and extrinsic pathways. Vasodilators include nitrophorins (nitric oxide storage and transport heme proteins), a variety of peptides that mimic endogenous vasodilatory neuropeptides, and proteins that catabolize or sequester endogenous vasoconstrictors. Multiple salivary proteins may be directed against each component of hemostasis, resulting in both redundancy and in some cases cooperative interactions between antihemostatic proteins. The complexity and redundancy of saliva ensures an efficient blood meal for the arthropod, but it also provides a diverse array of novel antihemostatic molecules for the pharmacologist.

Species Variation in the Mechanisms of Mesenchymal Stem Cell-Mediated Immunosuppression

Bone marrow-derived mesenchymal stem cells (MSCs) hold great promise for treating immune disorders because of their immunoregulatory capacity, but the mechanism remains controversial. As we show here, the mechanism of MSC-mediated immunosuppression varies

Effects of tetrabrominated diphenyl ether and hexabromocyclododecanes in single and complex exposure to hepatoma HepG2 cells

This study was designed to determine cytotoxic effects of PBDE-47 and HBCDs individually or with a mixture of both compounds exposure to Hep G2 cells. The results showed PBDE-47 and HBCDs induced increase of nitric oxide synthase (NOS) activity, release of NO. dissipation of mitochondria membrane potential and cell apoptosis. Exposure to HBCDs induced ROS formation. Moreover, preincubation with PTIO (NO scavanger) and N-acetylcysteine (ROS scavanger) partially reversed cytotoxic effects of these compounds. The possible mechanism is that PBDE-47 and HBCDs could boost generation of NO and/or ROS, impact mitochondria, and result in start-ups of apoptosis program. Cells exposed to mixture of both compounds and each of them showed non-apoptotic rate significant difference, but the combination of them caused more adverse effects on cells. These results Suggest that PBDE-47 and HBCDs in single and complex exposure have the cytotoxic activity of anti-proliferation and induction of apoptosis in tumor cells in vitro. (C) 2008 Elsevier B.V. All rights reserved.

Effects of hexachlorobenzene on antioxidant status of liver and brain of common carp (Cyprinus carpio)

Hexachlorobenzene (HCB)-induced oxidative damages have been published in rats while the effects have not yet been reported in fishes. Juvenile common carps (Cyprinus carpio) were exposed to waterborne HCB from 2 to 200 mu g l(-1) for 5, 10 or 20 days. Liver and brain were analyzed for various parameters of oxidative stress. There were no significant changes of glutathione (GSH) content and superoxide dismutase (SOD) activity in liver after 5 or 10 days exposure, whereas obvious drops were observed at higher concentrations after 20 days exposure. Significant decreases of GSH content and SOD activity in brain were found during all the exposure days. In brain, HCB also significantly elevated the contents of reactive oxygen species (ROS), thiobarbituric acid-reactive substances (TBARS, as an indicator of lipid peroxidation products), glutathione disulfide (GSSG), and activities of nitric oxide synthase (NOS), glutathione peroxidase (GPx), and glutathione reductase (GR), and inhibited activities of acetylcholinesterase (AchE) and glutathione S-transferase (GST). The results clearly demonstrated that environmentally possible level of HCB could result in oxidative stress in fish and brain was a sensitive target organ of HCB toxicity. (c) 2006 Elsevier Ltd. All rights reserved.

Design and characteristics of quantum cascade laser-based CO detection system

National High Technology Research and Development Program of China 2007AA03Z112；Program of Ministry of Education of China 20060183030；Program of Jilin Provincial Science and Technology Department of China 20070709；Program of Bureau of Science and Technology of Changchun City 2007107

一氧化氮（NO）对人肝癌细胞的重离子辐射增敏作用

为了探索一氧化氮（nitric oxide，NO）作为重离子治癌的辐射增敏剂的相关机理和应用前景，本课题采用NO与12C6+离子束(或X射线)辐照协同作用人肝癌细胞（SMMC-7721细胞和HepG2细胞），研究了NO与辐照相结合对两种细胞的生物学效应影响，为重离子治癌中放射增敏剂的临床应用提供一定的理论基础和实验依据。现得出结论如下： 1． 重离子辐射与X射线辐射相比，能够更有效地杀死肿瘤细胞。 2． NO能够增加肿瘤细胞的辐射敏感性。 3 NO的放射增敏效果在一定浓度范围内存在浓度效应关系。 4 NO对不同细胞系的辐射增敏作用效果并不完全相同

辐射诱导的HeLa细胞旁效应信号通路研究

随着肿瘤认识的不断深入，肿瘤外科学、肿瘤放射治疗学、肿瘤化学治疗学构成了现代肿瘤治疗学的三大支柱，而放射治疗学的研究对于肿瘤的治疗有重要的临床意义。本文通过对HeLa进行辐射来观察其产生的旁效应信号通路，从而对临床工作的起到一定的帮助。辐照过的细胞通过释放信号分子引起周围未辐照细胞产生一系列的生物学反应的现象，称之为辐射诱导的旁效应。活性氧（Reactive oxygen species, ROS）和一氧化氮（Nitric oxide, NO）是辐射诱导的旁效应信号通路中的两个重要信号分子。本文研究了这两种重要的信号分子在辐射诱导的HeLa细胞旁效应信号通路中的关系。通过微核实验，我们发现X射线以及12C6+ 辐照过的HeLa细胞及其旁观者细胞的微核形成明显增加，而1%的二甲亚砜（Dimethyl sulfoxide，DMSO，ROS清除剂）预处理X射线辐照的细胞则显著抑制了受辐照细胞及其旁观者细胞的微核形成。1 Gy的X射线辐照能够抑制细胞的增殖速率而0.5%和1%的DMSO预处理则能减少X射线的增殖抑制作用，并且DMSO预处理的效果与浓度有关：1%的DMSO比0.5%的DMSO处理更大程度的恢复了受辐照细胞的增殖速率。另一方面，接受条件培养基（Conditioned medium）的旁观者细胞的增殖速率增加，而DMSO预处理产生条件培养基的受辐照细胞则使旁观者细胞的增殖速率降低，且DMSO预处理的效果同样与其浓度相关：浓度越高，条件培养基的刺激生长作用越小。Western blotting和DAF-FM DA荧光探针检测分别显示了辐照过后细胞的诱导型一氧化氮合酶（Inducible nitric oxide synthase, iNOS）和NO水平均升高，而DMSO预处理则降低其水平。因此，我们推测在X射线辐照的HeLa细胞旁效应信号通路当中ROS是NO的上游信号。另外，我们采用培养基转移后立即加DMSO或BMS－345541（IKK/NF-κB抑制剂）的方法研究了旁观者细胞当中的旁效应信号通路。我们发现DMSO和BMS－345541均显著抑制了旁观者细胞的NO水平。因此，在旁观者细胞当中ROS与NF-κB均为NO的上游信号

Perovskite-Like Mixed Oxides (LaSrMn1-x Ni (x) O4+delta, 0 a parts per thousand currency sign x a parts per thousand currency sign 1) as Catalyst for Catalytic NO Decomposition: TPD and TPR Studies

Catalytic NO decomposition on LaSrMn1-x Ni (x) O4+delta (0 a parts per thousand currency sign x a parts per thousand currency sign 1) is investigated. The activity of NO decomposition increases dramatically after the substitution of Ni for Mn, but decreases when Mn is completely replaced by Ni (x = 1.0). The optimum value is at x = 0.8. These indicate that the catalytic performance of the samples is contributed by the synergistic effect of Mn and Ni. O-2-TPD and H-2-TPR experiments are carried out to explain the change of activity. The former indicates that only when oxygen vacancy is created, could the catalyst show enhanced activity for NO decomposition; the latter suggests that the best activity is obtained from catalyst with the most matched redox potentials (in this work, the biggest Delta T and Delta E values).

Oxygen Carrier Based on Hemoglobin/Poly(L-lysine)-block-poly(L-phenylalanine) Vesicles

An oxygen carrier was prepared by encapsulating carbonylated hemoglobin (CO-Hb) molecules into polypeptide vesicles made from poly(L-lysine)-block-poly(L-phenylalanine) (PLL-b-PPA) diblock copolymers in aqueous medium at pH 5.8. The encapsulation was confirmed by confocal laser scanning microscopy (CLSM). The morphology and size of the Vesicles were studied by field-emission scanning electron microscopy (ESEM). They had a spherical shape with it mean diameter of about 4 to 5 mu m. The encapsulation efficiency of hemoglobin was 40 wt %, and the hemoglobin content in the vesicles was 32 wt %. The CO-Hb encapsulated in the PLL-b-PPA vesicles was more stable than free CO-Hb under ambient conditions, In the presence of a O-2 atmosphere, the CO-Hb in the vesicle could be converted into oxygen-binding hemoglobin (O-2-Hb) under irradiation of visible light for 2 h. Therefore, the CO-Hb/PLL-b-PPA vesicles are expected to be used its red blood cell substitutes.

Effect of strontium substitution on the activity of La2-xSrxNiO4 (x=0.0-1.2) in NO decomposition

The aim of this work is to study the effect of Sr substitution on the redox properties and catalytic activity of La2-xSrxNiO4 (x = 0.0-1.2) for NO decomposition. Results suggest that the x = 0.6 sample shows the highest activity. The characterization (TPD, TPR, etc.) of samples indicates that the x = 0.6 sample possesses suitable abilities in both oxidation and reduction, which facilitates the proceeding of oxygen desorption and NO adsorption. At temperature below 700 degrees C, the oxygen desorption is difficult, and is the rate-determining step of NO decomposition. With the increase of reaction temperature (T > 700 degrees C), the oxygen desorption is favorable and, the active adsorption of NO on the active site (NO + V-o + Ni2+ -> NO--Ni3+) turns out to be the rate-determining step. The existence of oxygen vacancy is the prerequisite condition for NO decomposition, but its quantity does not relate much to the activity.