两株内生芽孢杆菌对盐胁迫下大豆幼苗超氧化物歧化酶和过氧化物酶活性影响

【背景】盐胁迫环境严重影响大豆幼苗生长,内生菌可提高作物的抗逆性。【目的】探究接种内生枯草芽孢杆菌127和解蛋白芽孢杆菌133对盐胁迫下大豆幼苗体内超氧化物歧化酶(superoxide dismutase,SOD)和过氧化物酶(peroxidase,POD)活性的影响。【方法】以“徐豆20”为实验材料,采用盆栽实验法,设置对照组、盐胁迫组和盐胁迫接菌组,在人工气候培养条件下,用不同NaCl浓度(50、100、150、200、250和300 mmol/L)处理大豆幼苗,并接种不同OD600值(OD0.33、OD0.50和OD0.75)的菌悬液。【结果】培养14 d,接种枯草芽孢杆菌127的菌悬液OD0.33和OD0.75分别在盐浓度300 mmol/L和100 mmol/L时,SOD活性均为1.04 U/g-FW;接种解蛋白芽孢杆菌133的菌悬液OD0.50在盐浓度300 mmol/L胁迫下POD活性最高为7 820 U/(g·min),对大豆幼苗修复效果较显著。培养28 d,接种枯草芽孢杆菌127的菌悬液OD0.50,在150 mmol/L时SOD活性最高(0.88 U/g-FW);接...     

改性纳米TiO2对蓝藻的生理生态影响

在自然光照条件和日光灯光照条件下,用掺1％Ag纳米TiO2、掺5％Fe2O3纳米TiO2、掺10％ZnO纳米TiO2和纯纳米TiO2对铜绿微囊藻（Synechocystis sp．）PCC6803和集胞藻（Microcystis aeruginosa）进行处理,并对2种藻样的叶绿素含量、类胡萝卜素含量、体外超氧自由基含量及超氧化物歧化酶（superoxidase dismutase,SOD）活性进行测定。结果表明,自然光照条件比日光灯光照条件更利于纳米材料光催化反应的进行;改性后的3种纳米材料对蓝藻的抑制效果要好于纯纳米TiO2,其中效果最好的为掺1％Ag纳米TiO2;2种藻样在适应由光催化剂引发光催化而产生的自由基胁迫时,集胞藻的适应能力比铜绿微囊藻更强。     

高压快速柱分离纯化牛血球超氧化物歧化酶的研究

以牛血球为材料,经溶血等处理和丙酮沉淀,获得牛血球超氧化物歧化酶粗品。此粗酶可以通过ＤＥＡＥ－Ｓｅｐｈａｒｏｓｅ和ＣＭ－Ｓｅｐｈａｒｏｓｅ快速柱层析,获得超氧化物歧化酶纯品。纯化的酶比活可达１３５００ｕ／ｍｇ,经ＰＡＧＥ、ＳＤＳ－ＰＡＧＥ和快速蛋白液相色谱（ＦＰＬＣ）检测,结果表明,纯化酶是均一的Ｓｅｐｈａｄｅｘ Ｇ－１００凝胶过滤测得该酶分子量为３１,８００,ＳＤＳ－ＰＡＧＥ测得亚基分子量为１５     

Palmin诱导烟草氧化猝发的机制

为探讨植物对病原微生物的防御机制和激发子启动植物体内的信号转导应答过程 ,本文研究了Phytoph thorapalmi激发子palmin诱导其非寄主亲和性烟草的叶片和悬浮细胞系产生氧化猝发的分子机理。利用生化分析和激光共聚焦显微扫描技术动态观察palmin诱导烟草过敏反应中O·- 2 和H2 O2 的形成、胞间转移及引起细胞死亡的特性。结果表明 :palmin诱导激活了烟草细胞内NADPH氧化酶 ,产生大量的O·- 2 ;O·- 2 在SOD催化下迅速转变成H2 O2 ,并且H2 O2 在一定范围的细胞间转移和积累 ,最后诱发烟草细胞的过敏性坏死反应。palmin诱导氧化猝发过程还有Ca2 和蛋白激酶的参与。     

Pyrimethamine induces oxidative stress in Plasmodium yoelii 17XL-infected mice: A novel immunomodulatory mechanism of action for an old antimalarial drug?

Pyrimethamine is an antimalarial drug that has also been used successfully to treat autoimmune diseases such as lymphoproliferative syndrome. In this work, the effect of pyrimethamine (PYR) on the production of free radicals in malaria-infected mice was studied to better understand the drug’s immunomodulatory properties. BALB/c and CBA/Ca mice were infected with Plasmodium yoelii 17XL. Seven days after infection, mice were treated with PYR or vehicle and sacrificed 24 h later. Treatment with PYR increased superoxide dismutase and glutathione peroxidase activities in erythrocytes and the liver, augmented the levels of nitric oxide in the serum, and upregulated mRNA levels of superoxide dismutase, glutathione peroxidase, catalase, and iNOS in the spleen. In addition, PYR increased lipoperoxidation and protein carbonylation in infected mice. Our results indicate that P. yoelii 17XL reduces oxidative stress in infected cells, while PYR induces it, which is associated with increased parasite elimination. Thus, it is possible that oxidative stress generated by pyrimethamine is also involved in its immunomodulatory mechanism of action.     

妊娠期糖尿病患者氧化应激水平变化及临床意义*

目的:研究GDM孕妇与正常孕妇血清MDA、SOD及GSH水平变化,探索它们与GDM之间的相互关系,追踪各组妊娠结局研究其临床意义。方法:选取175例孕妇为研究对象,分为GDM组(93例)和对照组(82例)。采用微量法测定血清丙二醛(MDA)、谷胱甘肽(GSH)及超氧化物歧化酶(SOD)水平,并对妊娠结局进行相关性分析。结果:(1) GDM组年龄、孕前体重、BMI值均高于对照组,GSH和SOD水平均低于对照组,MDA水平高于对照组,差异有统计学意义(P0.05);(2) GDM组MDA水平与孕前体重呈负相关(r=-0.3547,P0.05),SOD水平与新生儿出生体重呈正相关(r=0.3292,P0.05),SOD值与早产之间有密切联系(足月产12.68±0.85 vs.早产8.08±1.18, P 0.05),GSH、SOD水平与孕前体重之间,MDA、GSH水平与新生儿出生体重之间,MDA、GSH水平与早产之间均无明显相关性(P0.05),MDA、GSH和SOD水平与剖宫产及胎膜早破均无明显相关性(P0.05)。结论:GDM存在明显的氧化应激反应,GSH、MDA与SOD可以作为评估GDM氧化应激的有效标志物,其与不良妊娠结局有关。     

Bacterial Evolutionary Precursors of Eukaryotic Copper–Zinc Superoxide Dismutases

Internalization of a bacteria by an archaeal cell expedited eukaryotic evolution. An important feature of the species that diversified into the great variety of eukaryotic life visible today was the ability to combat oxidative stress with a copper–zinc superoxide dismutase (CuZnSOD) enzyme activated by a specific, high-affinity copper chaperone. Adoption of a single protein interface that facilitates homodimerization and heterodimerization was essential; however, its evolution has been difficult to rationalize given the structural differences between bacterial and eukaryotic enzymes. In contrast, no consistent strategy for the maturation of periplasmic bacterial CuZnSODs has emerged. Here, 34 CuZnSODs are described that closely resemble the eukaryotic form but originate predominantly from aquatic bacteria. Crystal structures of a Bacteroidetes bacterium CuZnSOD portray both prokaryotic and eukaryotic characteristics and propose a mechanism for self-catalyzed disulfide maturation. Unification of a bacterial but eukaryotic-like CuZnSOD along with a ferredoxin-fold MXCXXC copper-binding domain within a single polypeptide created the advanced copper delivery system for CuZnSODs exemplified by the human copper chaperone for superoxide dismutase-1. The development of this system facilitated evolution of large and compartmentalized cells following endosymbiotic eukaryogenesis.     

Bioavailability of metalloporphyrin-based SOD mimics is greatly influenced by a single charge residing on a Mn site

Abstract

In the cell Mn porphyrins (MnPs) likely couple with cellular reductants which results in a drop of total charge from 5+ to 4+ and dramatically increases their lipophilicity by up to three orders of magnitude depending upon the length of alkylpyridyl chains and type of isomer. The effects result from the interplay of solvation, lipophilicit and stericity. Impact of ascorbate on accumulation of MnPs was measured in E. coli and in Balb/C mouse tumours and muscle; for the latter measurements, the LC/ESI-MS/MS method was developed. Accumulation was significantly enhanced when MnPs were co-administered with ascorbate in both prokaryotic and eukaryotic systems. Further, MnTnHex-2-PyP⁵⁺ accumulates 5-fold more in the tumour than in a muscle. Such data increase our understanding of MnPs cellular and sub-cellular accumulation and remarkable in vivo effects. The work is in progress to understand how coupling of MnPs with ascorbate affects their mechanism of action, in particular with respect to cancer therapy.     

Health applications of bioactive compounds from marine microalgae

Marine microalgae and cyanobacteria are very rich in several chemical compounds and, therefore, they may be used in several biological applications related with health benefits, among others. This review brings the research up-to-date on the bioactive compounds produced by marine unicellular algae, directly or indirectly related to human health. It covers and goes through the most studied applications of substances such as PUFA, sterols, proteins and enzymes, vitamins and pigments, in areas so diverse as human and animal nutrition, therapeutics, and aquaculture. The great potential of marine microalgae and the biocoumpounds they produce are discussed in this review.