Catalase, but not MnSOD, inhibits glucose deprivation-activated ASK1-MEK-MAPK signal transduction pathway and prevents relocalization of Daxx: hydrogen peroxide as a major second messenger of metabolic oxidative stress

Overexpression of catalase, but not manganese superoxide dismutase (MnSOD), inhibited glucose deprivation-induced cytotoxicity and c-Jun N-terminal kinase 1 (JNK1) activation in human prostate adenocarcinoma DU-145 cells. Suppression of JNK1 activation by catalase overexpression resulted from inhibition of apoptosis signal-regulating kinase 1 (ASK1) activation by preventing dissociation of thioredoxin (TRX) from ASK1. Overexpression of catalase also inhibited relocalization of Daxx from the nucleus to the cytoplasm as well as association of Daxx with ASK1 during glucose deprivation. Taken together, hydrogen peroxide (H(2)O(2)) rather than superoxide anion (O(2) (*-)) acts as a second messenger of metabolic oxidative stress to activate the ASK1-MAPK/extracellular signal-regulated kinase (ERK) kinase (MEK)-mitogen-activated protein kinase (MAPK) signal transduction pathway.     

Rht10基因对‘鲁麦15’农艺性状和光合生理特性的影响

利用鲁麦15、Rht10鲁麦15、Ms2鲁麦15及Ms2+Rht10鲁麦15近等基因系为试验材料,研究了Rht10基因对小麦农艺性状、净光合速率(Pn)、蒸腾速率(Tr)等光合生理特性的影响.结果表明,Rht10使小麦的挑旗、抽穗、开花期均推迟了4～5 d;Rht10对鲁麦15和Ms2鲁麦15的降秆强度分别为53.77%和53.00%,穗长显著缩短(P<0.05),千粒重显著减少,但对有效穂数无显著影响(P>0.05).含有Rht10基因的材料与不含此基因的材料之间的光合生理参数普遍存在显著差异,但在不同时期不同参数差异正负不同;在灌浆后期,Rht10对Pn有显著正效应(P<0.05);从开花期到灌浆后期,Pn与气孔导度(Gs)、胞间二氧化碳浓度(Ci)总体变化趋势相同,且相关性显著,表明Pn在一定程度上受气孔因素的限制;在灌浆中后期,Rht10对Gs有明显的正效应;在抽穗和开花期,Rht10对Tr有明显的正效应;Rht10对叶片水分利用效率(WUE)在4个生育期有明显的负效应.由此可见,Rht10基因对小麦的生育期、株高、穗长都有明显的不利影响,对各项光合生理参数也有普遍正向或负向的影响,在利用Rht10进行杂交育种时应充分考虑此基因带来的不利效应.     

Trigoxyphins H and I: two new daphnane diterpenoids from Trigonostemon xyphophylloides

Two new daphnane diterpenoids (1 and 2), together with four known analogues (3-6) were isolated from Trigonostemon xyphophylloides. Their structures were elucidated by spectroscopic analysis. Compounds 1 and 2 were evaluated for in vitro cytotoxic activities against the SPCA-1 (human lung cancer) and BEL-7402 (human hepatocellular carcinoma) cancer cell lines. Trigoxyphin I (2) showed modest cytotoxicity against two tumor cell lines.     

Simulation of sequential batch reactor (SBR) operation for simultaneous removal of nitrogen and phosphorus

Modeling of the operation of sequential batch reactor (SBR) was performed to find out optimum design parameters for simultaneous removal of nitrogen and phosphorus in a small-scale wastewater treatment plant. The models were set up with material balances on SBR operation and Monod kinetics. The model parameters were obtained to best fit the experimental results in a small scale SBR. The models were useful in optimizing hydraulic retention time (HRT) and successfully simulated operations of SBR in a larger scale. Especially the model predicted well the reactions occurring in the filling period as well as the effect of dilution, and evaluated the performance of SBR process under diverse operating conditions.     

Influence of magnesium ions on biofilm formation by Pseudomonas fluorescens

Mg²⁺ can potentially influence bacterial adhesion directly through effects on electrostatic interactions and indirectly by affecting physiology-dependent attachment processes. However, the effects of Mg²⁺ on biofilm structure are largely unknown. In this study, Pseudomonas fluorescens was used to investigate the influence of Mg²⁺ concentration (0, 0.1 and 1.0 mM MgCl₂) on biofilm growth. Planktonic and attached cells were enumerated (based on DAPI staining) while biofilm structures were examined via confocal laser scanning microscopy and three-dimensional structures were reconstructed. Mg²⁺ concentration had no influence on growth of planktonic cells but, during biofilm formation, Mg²⁺ increased the abundance of attached cells. For attached cells, the influence of Mg²⁺ concentration changed over time, suggesting that the role of Mg²⁺ in bacterial attachment is complex and dynamic. Biofilm structures were heterogeneous and surface colonization and depth increased with increasing Mg²⁺ concentrations. Overall, for P. fluorescens, Mg²⁺ increased initial attachment and altered subsequent biofilm formation and structure.     

Clinical manifestation, imaging, and genotype analysis of two pedigrees with spinocerebellar ataxia

The objective of this study was to analyze the clinical manifestation, imaging characteristics, genotype, and the relationship between the three aforementioned parameters in two pedigrees suffering from spinocerebellar ataxia. To evaluate the clinical manifestation of the two pedigrees and to compare the characteristics, we performed the MRI analysis of some patients from both pedigrees, while 2 ml of the peripheral blood sample was collected for gene analysis. The gene analysis data showed that pedigree 1 was certified spinocerebellar ataxia type-2 (SCA2); the CAG repeats in the proband, proband’s mother, and proband’s brother were 44, 36, and 38, respectively. The MRI revealed brainstem cerebellar atrophy and “cross sign” and “ordinate sign” of pons. Pedigree 2 was certified SCA1; the CAG repeats of the proband, proband’s aunt, and proband’s asymptomatic cousin were 60, 51, and 52, respectively. The MRI revealed cerebellar atrophy in these individuals. We, therefore, concluded that it was difficult to diagnose the SCA subset solely through the clinical manifestation. The imaging characteristics analysis and final diagnosis depended basically on gene analysis data.     

重金属镉、锌在菹草叶细胞中的超微定位观察

水环境污染中十分突出的是重金属的污染 ,主要来源为流入物、渗漏和大气沉降 (Ｌａｒｃｈｅｒ ,1995 )。由于重金属污染物不但不能被微生物所分解 ,而且能在生物体内富集 ,并通过水生食物链的生物放大作用而对高营养级的生物甚至人类造成危害 ,因此日益引起人们的特别关注。许多研究从超微结构损伤和生理生化的角度研究了重金属对植物的毒害机制。施国新等 (2 0 0 0 )观察了重金属汞、镉污染对水生植物黑藻叶细胞的超微结构损伤。彭鸣等 (1991)研究了重金属镉、铅诱导的玉米超微结构的变化。李荣春 (2 0 0 0 )研究了Ｃｄ、Ｐｂ及其复合污染…     

不同预处理对大麦花药3种内源激素含量和过氧化物酶活性的影响

研究了大麦（Ｈｏｒｄｅｕｍ ｖｕｌｇａｒｅ Ｌ．）花药－花粉培养中不同预处理对花药内源激素（ＡＢＡ,ＩＡＡ,ＩＰＡ）含量和过氧化物酶活性的影响。结果表明：１． 经甘露醇预处理不同天数,同一种基因型的３种内源激素的变化和不同基因型的同一种内源激素的变化规律十分相似,均是在预处理初期含量急剧增加,最高值在０．５或１ ｄ 处。以后开始逐渐下降;最后,保持在一定的水平上。２． 在甘露醇预处理过程中,两种基因型花药过氧化物酶活性的变化规律也十分相似。在预处理前期（从开始到第３天）活性呈直线上升,第３天达到最大值。从第３天到第５天活性减弱。最后,活性又开始增强。３． 在低温预处理过程的初期（２～５ ｄ） 两种基因型花药过氧化物酶活性都出现第一个小峰。在第１４天（“Ｈａｒｒｉｎｇｔｏｎ”）或第２１天（“Ｉｇｒｉ”）又出现第二个峰值,但后者较高。在预处理的后期（从第２８天到第３５天）两种基因型花药过氧化物酶的活性又呈现上升的趋势。同甘露醇预处理后期变化一致