铅、锌及其交互作用对鱼腥草(Houttuynia cordata)叶绿素含量及抗氧化酶系统的影响

采用营养液培养方法研究铅、锌及其交互作用对鱼腥草叶绿素含量及抗氧化酶系统的影响。实验结果显示，随着Pb浓度的增加，鱼腥草叶绿素含量逐渐降低但无显著变化。Zn在一定浓度下能提高鱼腥草叶绿素含量，而在高浓度Zn胁迫下，叶绿素含量急剧下降。鱼腥草叶片中SOD、POD和CAT3种酶活性都是随着Pb浓度的增加先上升后下降。随着Zn浓度的增加，SOD和CAT也是先上升后下降，POD则是逐渐上升。Pb—Zn交互作用增加了鱼腥草叶绿素含量，对SOD和POD活性具有抑制作用，对CAT活性影响不明显。同时研究结果还表明，单一Pb、Zn对鱼腥草叶绿素含量和抗氧化酶系统的影响大于Pb、Zn二者的共同作用，其中高浓度Zn对鱼腥草的伤害作用最大，而当溶液Pb处理浓度达到400mg／L时，鱼腥草仍能正常生长，说明鱼腥草具有较强的耐Pb能力。     

Cd、Zn复合污染对水车前叶绿素含量和活性氧清除系统的影响

主要研究了重金属Cd、Zn单一及复合污染对水车前叶绿素含量和活性氧清除系统的影响。超氧化物歧化酶 (SOD)、过氧化物酶 (POD)、过氧化氢酶 (CAT)活性都在 0 1mg·L-1Cd处理浓度时达到峰值 ,随培养浓度的增加 ,活性下降。叶绿素含量则随处理的浓度的上升而呈递减趋势。在各Cd处理梯度中加入Zn后 ,随加入Zn浓度的增大 ,上述各指标与单一Cd处理差异显著性增强 ,表明Zn增强了Cd的毒害作用 ,显示出协同作用的趋势     

铅、锌及其交互作用对鱼腥草(Houttuynia cordata)叶绿素含量及抗氧化酶系统的影响

采用营养液培养方法研究铅、锌及其交互作用对鱼腥草叶绿素含量及抗氧化酶系统的影响。实验结果显示,随着Pb浓度的增加,鱼腥草叶绿素含量逐渐降低但无显著变化。Zn在一定浓度下能提高鱼腥草叶绿素含量,而在高浓度Zn胁迫下,叶绿素含量急剧下降。鱼腥草叶片中SOD、POD和CAT 3种酶活性都是随着Pb浓度的增加先上升后下降。随着Zn浓度的增加,SOD和CAT也是先上升后下降, POD则是逐渐上升。Pb-Zn交互作用增加了鱼腥草叶绿素含量,对SOD和POD活性具有抑制作用,对CAT活性影响不明显。同时研究结果还表明,单一Pb、Zn对鱼腥草叶绿素含量和抗氧化酶系统的影响大于Pb、Zn二者的共同作用,其中高浓度Zn对鱼腥草的伤害作用最大,而当溶液Pb处理浓度达到400mg/L时,鱼腥草仍能正常生长,说明鱼腥草具有较强的耐Pb能力。     

Cd、Cr(VI)单一及复合污染对菹草叶绿素含量和抗氧化酶系统的影响

主要研究了 Cd、Cr( VI)单一及复合污染对菹草叶绿素含量和抗氧化酶系统的影响 ,研究结果表明 :随 Cd、Cr( VI)胁迫浓度的增加 ,菹草总叶绿素含量下降 ,单一 Cd处理 SOD活性下降 ,POD和 CAT活性表现出先升后降的趋势 ,Cd、Cr( VI)复合污染的效应明显大于单一污染的效应。     

镉、铜和锌胁迫下黑藻活性氧的产生及抗氧化酶活性的变化研究

研究了不同Cd、Cu、Zn处理浓度对黑藻体内活性氧()产生及对抗氧化酶(SOD、POD、CAT)活性的分子毒理学效应以探讨高等水生植物抗氧化酶对重金属胁迫的反应。结果表明,三种重金属都不同程度地加快了产生速率;Cu使SOD、POD、CAT活性下降;Cd也都减弱了SOD和POD活性,而CAT活性在0.5—5mg/L处理浓度时增加;Zn对SOD活性也为抑制作用,当浓度为0.5—5mg/L时POD和CAT活性都上升。关联度分析发现Cd、Cu和Zn胁迫下黑藻起主要保护作用的分别为SOD、POD和CAT,而SOD最易受到影响。Cd、Cu处理下的叶绿素含量也都呈下降趋势,而0.5—5mg/L的Zn浓度刺激了叶绿素合成。所有Zn处理、0.5mg/L的Cu处理和0.5—1mg/L的Cd处理的叶绿素a/b值都大于对照值。除了Cu使可溶性蛋白含量减少外,0.5—5mg/L的Zn和0.5—1mg/L的Cd都使其含量增加。综合起来,Cu的毒性最强,其次为Cd,Zn最弱。致死阈浓度分别为:Cu:0.5—1mg/L;Cd:1—2mg/L;Zn:5—6mg/L。SOD是评价重金属对沉水植物毒性效应的灵敏指标。黑藻对水环境Cu污染反应敏感。       

Cd、Cr（Ⅵ）单一及复合污染对菹草叶绿素含量和抗气体酶系统的影响

主要研究了Cd、Cr(Ⅵ）单一及复合污染对菹草叶绿素含量和抗氧化酶系统的影响,研究结果表明：随Cd、Cr(Ⅵ）腔迫浓度的增加,菹草总叶绿素含量下降,单一Cd处理SOD活性下降,POD和CAT活性表现出先升后降的趋势,Cd、Cr(Ⅵ）复合污染的效应明显大于单一污染的效应。     

化学催熟剂对油菜角果叶绿素含量及抗氧化酶系统的影响

采用大田试验研究了两种化学催熟剂（敌草快和农达）对生长后期油菜角果的叶绿素含量、抗氧化酶系统（CAT、SOD、POD活性）、细胞膜透性及MDA含量的影响.结果表明：采用敌草快催熟,油菜角果皮叶绿素含量下降,SOD、POD、CAT活性及细胞膜透性和MDA含量显著提高,导致角果膜脂过氧化,且作用强度随处理浓度的增加而增加;采用农达催熟,油菜角果皮叶绿素含量所受影响较小,SOD、POD和CAT活性上升缓慢,细胞膜透性和MDA含量增加不明显.随着催熟时间的推移,油菜角果保护酶活性受到不同程度的抑制,这可能与催熟剂干扰酶系统分子结构有关.     

外源5 氨基乙酰丙酸对盐胁迫下决明幼苗生理特性的影响

为寻找提升决明幼苗耐盐性的方法,测量了不同处理下决明幼苗叶片的光合色素、超氧阴离子、丙二醛的含量,以及保护酶系统中SOD、POD、CAT的活性。结果表明,经150 mmol?L 1 NaCl处理,决明幼苗叶片的光合色素含量显著降低,而超氧阴离子、丙二醛的含量以及保护酶SOD、POD、CAT的活性显著升高。不同浓度的外源5 氨基乙酰丙酸在不同程度上增加了决明幼苗叶片的叶绿素、类胡萝卜素含量,进一步增强了保护〖JP2〗酶SOD、POD、CAT的活性,降低了超氧阴离子、丙二醛的含量。在外源5 氨基乙酰丙酸浓度为50 mg?L 1时,恢复效果最为明显(80.0 、196.4 和 114.1 U?g 1),有效地缓解了盐胁迫对决明幼苗的伤害。     

Hg、Cd及共同作用对烟草叶绿素含量及抗氧化酶系统的影响

 本文报道了Hg、Cd及二者共同作用明显不同程度地影响烟草叶绿素含量及抗氧化酶系统。受Hg、Cd胁迫后,随着土壤中Hg、Cd浓度的增加,叶绿素含量、叶绿素a／b值、CAT活性逐渐减小,SOD活性先升后降,POD活性则逐渐增加。同时也表现出单一Hg、Cd对烟草叶绿素含量及抗氧化酶系统的影响明显大于Hg、Cd二者的共同作用。     

高氯酸盐和铬复合污染对水稻生理特性的影响

通过盆栽试验,研究了不同浓度高氯酸盐(ClO4-)、六价铬(Cr6+)及其复合污染(ClO4-+Cr6+)胁迫条件下水稻叶片叶绿素荧光参数、叶绿素含量和水稻体内抗氧化酶活性及丙二醛含量的变化。结果表明,随着ClO4-、Cr6+和ClO4-+Cr6+处理浓度的升高,水稻叶片叶绿素荧光参数Fv/F0、Fv/Fm和叶绿素含量均明显下降,且生长前期下降程度高于后期;ClO4-、Cr6+及ClO4-+Cr6+均可显著提高水稻体内POD酶(peroxidase)、CAT酶(catalase)活性和MDA(malondialdehyde)含量,且复合处理显著高于单一处理;分蘖期水稻体内SOD酶(superoxide dismutase)活性随着污染物浓度的增加明显降低,而在抽穗期其SOD酶活性升高。复合处理对水稻的损伤和毒害作用比单一处理更为严重,其交互作用机理值得进一步研究。     

CD34+-derived CD11c+ + + BDCA-1+ + CD123+ + DC: expansion of a phenotypically undescribed myeloid DC1 population for use in adoptive immunotherapy

BACKGROUND: DC are commonly defined as HLA-DR+/Lin- cells that can be CD11c+ + + CD123+/ -, termed DC1/myeloid DC that induce a Th1 response, or CD11c- CD123+ + +, termed DC2/lymphoid DC that induce a Th2 response. However, significant heterogeneity within DC preparations is apparent and supports the existence of several distinct DC subpopulations. This study aimed to expand and characterize CD34+ DC for use in immunotherapy. METHODS: CD34+ cells were seeded at 1 x 10(5)/mL and expanded for 14 days in RPMI + 10% autologous plasma supplemented with GM-CSF, IL-4, Flt-3L and SCF. Maturation was induced with TNF-alpha and PGE2 for 2 days. DC were analyzed morphologically, phenotypically with a panel of MAb to lineage and DC markers, and functionally in MLR, T-cell assays and T-cell cytokine secretion by ELISA. RESULTS: Significant cellular expansion was observed: 60+/-5 x 10(6) DC from 1 x 10(6) CD34+ cells (n=28). Phenotypically DC were characterized as HLA-DR+ +, CD11c+ + +, CD80+ +, CD83+, CD86+ +, CD123+ +, CD15+ +, CD33+ +, BDCA-1+ +, CD4+ and Lin-. DC displayed potent allostimulatory capacity and efficient presentation of KLH and tetanus toxin. DC-primed T cells secreted IFN-gamma (Th1); however, no detectable IL-4 (Th2) was noted. DISCUSSION: We present features of CD34+ DC that have not been previously described. The CD34+ DC generated represent a population of myeloid DC functioning as DC1 but phenotypically expressing markers characteristic of both DC1 and DC2. This novel DC population is capable of inducing naive T-cell responses and can be expanded to clinically useful numbers. CD34+-derived DC represent attractive candidates for use in adoptive T-cell immunotherapy.     

抗VacA+CagA+幽门螺杆菌IgY的抗感染作用研究

为研究抗VacA CagA 幽门螺杆菌(Hp)IgY的抗感染作用,以VacA CagA Hp为抗原免疫蛋鸡,聚乙二醇法和水稀释法从鸡卵黄中提取抗-VacA CagA Hp-IgY,酶联免疫吸附实验(ELISA)测定IgY抗体效价。建立胃腔感染VacA CagAHp的昆明系小鼠模型,观察抗-VacA CagA Hp-IgY对小鼠胃腔感染VacA CagA Hp的防治效果。ELISA法测定IgY效价均为1∶20,480;抗-VacA CagA Hp-IgY防治小鼠胃腔感染VacA CagAHp效果较理想,IgY高、中剂量组效果优于阳性对照组(P<0.05);低剂量组效果等同于阳性对照组(P>0.05)。抗-VacA CagA Hp-IgY较好的体内抗感染作用,提示该IgY有望成为较理想的治疗VacA CagA Hp感染的生物制剂。     

Hydrolysis of adenylyl imidodiphosphate in the presence of Na+ + Mg+ by (Na+ + K+)-activated ATPase

(1) Contrary to what has usually been assumed, (Na⁺ + K⁺)-ATPase slowly hydrolyses AdoPP[NH]P in the presence of Na⁺ + Mg²⁺ to ADP-NH₂ and P_i. The activity is ouabain-sensitive and is not detected in the absence of either Mg²⁺ or Na²⁺. The specific activity of the Na⁺ + Mg²⁺ dependent AdoPP[NH]P hydrolysis at 37°C and pH 7.0 is 4% of that for ATP under identical conditions and only 0.07% of that for ATP in the presence of K⁺. The activity is not stimulated by K⁺, nor can K⁺ replace Na⁺ in its stimulatory action. This suggests that phosphorylation is rate-limiting. Stimulation by Na⁺ is positively cooperative with a Hill coefficient of 2.4; half-maximal stimulation occurs at 5–9 mM. The K_m value for AdoPP[NH]P is 17 μM. At 0°C and 21°C the specific activity is 2 and 14%, respectively, of that at 37°C. AMP, ADP and AdoPP[CH₂]P are not detectably hydrolysed by (Na⁺ + K⁺)-ATPase in the presence of Na⁺ + Mg²⁺. (2) In addition, AdoPP[NH]P undergoes spontaneous, non-enzymatic hydrolysis at pH 7.0 with rate constants at 0, 21 and 37°C of 0.0006, 0.006 and 0.07 h^?1, respectively. This effect is small compared to the effect of enzymatic hydrolysis under comparable conditions. Mg²⁺ present in excess of AdoPP[NH]P reduces the rate constant of the spontaneous hydrolysis to 0.005 h^?1 at 37°C, indicating that the MgAdoPP[NH]P complex is virtually stable to spontaneous hydrolysis, as is also the case for its enzymatic hydrolysis. (3) A practical consequence of these findings is that AdoPP[NH]P binding studies in the presence of Na⁺ + Mg²⁺ with enzyme concentrations in the mg/ml range are not possible at temperatures above 0°C. On the other hand, determination of affinity in the (Na⁺ + K⁺)-ATPase reaction by competition with ATP at low protein concentrations (μg/ml range) remains possible without significant hydrolysis of AdoPP[NH]P even at 37°C.     

Different cation sensitivities and binding site domains of Na+-Ca2+-K+ and Na+-Ca2+ exchangers

We examined inhibitory effects of external multivalent cations Ni(2+), Co(2+), Cd(2+), La(3+), Mg(2+), and Mn(2+) on reverse-mode exchange of the K(+)-dependent Na(+)/Ca(2+) exchanger NCKX2 and the K(+)-independent exchanger NCX1 expressed in CCL-39 cells by measuring the rate of Ca(2+) uptake with radioisotope tracer and electrophysiological techniques. The apparent affinities for block of Ca(2+) uptake by multivalent cations was higher in NCKX2 than NCX1, and the rank order of inhibitory potencies among these cations was different. Additional experiments also showed that external Li(+) stimulated reverse-mode exchange by NCX1, but not NCKX2 in the presence of 5 mM K(+). Thus, both exchangers exhibited differential sensitivities to not only K(+) but also many other external cations. We attempted to locate the putative binding sites within the alpha motifs for multivalent cations by site-directed mutagenesis experiments. The cation affinities of NCKX2 were altered by mutations of amino acid residues in the alpha-1 motif, but not by mutations in the alpha-2 motif. These results contrast with those for NCX1 where mutations in both alpha-1 and alpha-2 motifs have been shown previously to affect cation affinities. Susceptibility tests with sulfhydryl alkylating agents suggested that the alpha-1 and alpha-2 motifs are situated extracellularly and intracellularly, respectively, in both exchangers. A topological model is proposed in which the extracellular-facing alpha-1 motif forms an external cation binding site that includes key residues N203, G207C, and I209 in NCKX2, while both alpha-1 and alpha-2 motifs together form the binding sites in NCX1.     

The effect of Na+ and K+ on the thermal denaturation of Na+ and + K+-dependent ATPase.

To increase our understanding of the physical nature of the Na+ and K+ forms of the Na+ + K+-dependent ATPase, thermal-denaturation studies were conducted in different types of ionic media. Thermal-denaturation measurements were performed by measuring the regeneration of ATPase activity after slow pulse exposure to elevated temperatures. Two types of experiments were performed. First, the dependence of the thermal-denaturation rate on Na+ and K+ concentrations was examined. It was found that both cations stabilized the pump protein. Also, K+ was a more effective stabilizer of the native state than was Na+. Secondly, a set of thermodynamic parameters was obtained by measuring the temperature-dependence of the thermal-denaturation rate under three ionic conditions: 60 mM-K+, 150 mM-Na+ and no Na+ or K+. It was found that ion-mediated stabilization of the pump protein was accompanied by substantial increases in activation enthalpy and entropy, the net effect being a less-pronounced increase in activation free energy.     

Lyt phenotype of cytotoxic T cells: shift from Lyt-1+2+3+ to a mixed population of Lyt-1+2+3+ and Lyt-1-2+3+ during in vitro culture

The Lyt phenotype of cytotoxic T cells generated in the primary H-2 response was investigated kinetically. The cytotoxicity generated in the early stage of culture was abolished by treatment with alpha Lyt-1,2,3, and complement (C), whereas that generated in the late stage was only partially eliminated by alpha Lyt-1, but was abolished by alpha Lyt-2, 3, and C. This suggested late expansion of the Lyt-1-2+3+ population. Lack of Lyt-1 antigen was confirmed with cells that were depleted of Lyt-1+ from primary culture and then stimulated in the secondary response by elimination of cytotoxicity and by direct Lyt typing. Results indicated that the response of proliferative and cytotoxic T cells of the Lyt-1+2+3+ phenotype in the early stage of culture was followed by activation of Lyt-1-2+3+ T cells. Cytotoxic T cells in the late stage were shown to be a mixture of Lyt-1+2+3+ and Lyt-1-2+3+ cells. This was confirmed with cytotoxic T cells from secondary culture and uncloned long-term T cell lines.