Changes of Photosystem Ⅱ Electron Transport in the ChlorophyⅡ-deficient Oilseed Rape Mutant Studied by ChlorophyⅡ Fluorescence and Thermoluminescence

The photosystem Ⅱ （PSII） complex of photosynthetic membranes comprises a number of chlorophyll-binding proteins that are important to the electron flow. Here we report that the chlorophyll b-deficient mutant has decreased the amount of light-harvesting complexes with an increased amount of some core polypeptldes of PSII, including CP43 and CP47. By means of chlorophyll fluorescence and thermolumlnescence, we found that the ratio of Fv/Fm, qP and electron transport rate in the chlorophyll b-deficient mutant was higher compared to the wild type. In the chlorophyll lPdeflclent mutant, the decay of the primary electron acceptor quinones （QA-） reoxidation was decreased, measured by the fluorescence. Furthermore, the thermoluminescence studies in the chlorophyll bdeficient mutant showed that the B band （S2/S3QB-） decreased slightly and shifted up towards higher temperatures. In the presence of dlchlorophenyl-dlmethylurea, which is inhibited in the electron flow to the second electron acceptor quinines （QB） at the PSll acceptor side, the maximum of the Q band （S2QA-） was decreased slightly and shifted down to lower temperatures, compared to the wild type. Thus, the electron flow within PSll of the chlorophyⅡ b-deficient mutant was down-regulated and characterized by faster oxidation of the primary electron acceptor quinine QA-via forward electron flow and slower reduction of the oxidation S states.     

BAY 41-2272防治大鼠Thy-1肾炎的实验研究

目的:观察比较BAY41-2272和己酮可可碱(PTX)这两种增强环磷酸鸟苷(cGMP)活性的物质对大鼠Thy-1诱导的进展性肾病模型的疗效,探讨肾纤维化治疗的新途径。方法:成功诱导Thy-1肾炎后,将大鼠分为四组:即肾纤维化组(RF组)、BAY 41-2272治疗组、PTX治疗组和对照组。治疗15周后,分别检测各组大鼠血清肌酐和尿蛋白排泄量,肾组织病理和免疫组化方法检测肾小球/小管间质基质堆积程度和ED1/PCNA阳性细胞数,检测肾小球和皮质转化生长因子TGF-β1、纤粘蛋白(fi- bronectin)、基质金属蛋白酶抑制物(TIMP-1)等蛋白能表达水平,ELISA方法检测肾小球/小管间质细胞的基础、刺激后cGMP水平。RT-PCR方法检测内皮细胞一氧化氮合成酶、α1/β1可溶性鸟苷酸环化酶mRNA水平。结果:观察结束时,BAY41-2272显著降低大鼠尿蛋白排泄和血肌酐水平,显著减轻肾小球/小管间质基质堆积程度,降低巨噬细胞浸润数目和TGF-β1、fibronectin表达水平,而PTX治疗仅产生轻微的变化。肾纤维化组大鼠的小管间质sGC mRNA、NO刺激的cGMP水平显著高于对照组,而肾小球的则较对照组降低;BAY41-2272治疗后肾小球/小管间质sGC mRNA、刺激后cGMP水平可显著提高,而PTX治疗的只有轻度提高而无统计学意义。结论:BAY41-2272治疗可显著改善肾组织NO-cGMP信号通路转导和cGMP的活性,可有效的延缓肾纤维化的进展,而PTX疗效则相对很弱。采用BAY41-2272提高cGMP活性的方案可能为肾纤维化提供新颖、极具前景的治疗策略。     

C3d3通过促进脾脏B细胞高表达CXCR4增强hCGβ DNA免疫体液免疫效应

本文旨在探讨分子佐剂C3d3与hCGβ融合在基因免疫中增强抗hCGβ体液免疫效应的机制。分别用质粒pCMV4-hCGB-C3d3、pCMV4-hCGβ和pCMV4免疫BALB/c小鼠,间接ELISA法检测免疫小鼠外周血IgG/IgA类抗hCGβ抗体水平;ELISPOT分析免疫鼠脾脏组织IgG/IgA类抗体分泌细胞水平(ASC);RT-PCR分析免疫鼠脾脏B细胞趋化因子受体表达,RT-PCR和FCM分析CXCR4表达水平;RT-PCR和ELISA检测脾脏组织CXCL12表达水平。结果显示,pCMV4- hCGβ-C3d3免疫组外周血IgG类抗hCGβ抗体水平明显高于pCMV4-hCGβ免疫组;而IgA类抗hCGβ抗体水平在两组间无明显差异。pCMV4-hCGβ-C3d3免疫组脾脏组织IgG类ASCs水平明显高于pCMV4-hCGβ组;两组间IgA类ASCs水平无明显差异。经pCMV4-hCGB、pCMV4-hCGβ- C3d3免疫鼠脾脏B细胞CXCR4表达明显高于对照组;且pCMV4-hCGβ-C3d3组明显高于pCMV4-hCGβ免疫组。CXCR4~ 细胞与ASCs呈正相关,r=0.966,(P<0.05)。pCMV4-hCGβ-C3d3和pCMV4-hCGβ组脾脏组织CXC L12表达均显著高于对照组。结果表明,分子佐剂C3d3与hCGβ基因融合,在基因免疫小鼠后能够显著升调节脾脏ASCs CXCR4表达,从而可能增强抗hcGβ基因疫苗的体液免疫效应。     

实验性动脉粥样硬化家兔MIF、TNF-α和IL-6水平的研究

目的:对实验性动脉粥样硬化家兔血清中巨噬细胞移动抑制因子、肿瘤坏死因子、白介素-6含量进行分析,以探讨它们在冠心病发病过程中的意义。方法:研究对象为新西兰大白兔,随机分成对照组(10只)和实验组(10只)。对照组喂食基础饲料,实验组喂食高脂饲料(基础饲料中加入1%胆固醇 5%猪油)。均喂饲8周后采用ELISA法检测其血清MIF、TNF-α、IL-6水平。结果:组织病理切片结果显示实验组兔主动脉弓内膜增厚,动脉粥样斑块明显。与对照组比较,实验组MIF、TNF-α、IL-6水平均升高,其差别有显著性(p＜0．01)。结论:MIF、TNF-α、IL-6与动脉粥样硬化的发生有密切关系,这些细胞因子可通过相互诱导、相互协同共同参与冠心病的发生、发展过程。     

农杆菌介导的转化芦荟的研究

芦荟（Aloe）是美容和医疗保健工业的重要植物资源,然而基因工程途径改良芦荟鲜有报道。本实验研究了次氯酸钠、升汞不同浓度和时间对芦荟外植体的灭菌效果,比较了芦荟不同部位（叶片、叶鞘和茎段）的再生能力,利用GUS基因瞬间表达技术（X-Gluc染色）探讨了不同农杆菌对不同芦荟外植体的侵染效果,确定了G418筛选剂在芦荟转化后的最适筛选浓度,摸索了适宜于农杆菌—芦荟共培养用培养基组成和共培养条件,通过转化、筛选和移栽共获得了67棵抗性再生植株,进一步对抗性再生植株进行了PCR、Southern blotting和ELISA检测。结果表明,芦荟外植体灭菌方法为20.0%次氯酸钠溶液浸泡25min,效果优于利用0.1%升汞灭菌处理,茎部切段的再生能力高于叶片切段和叶鞘切段,适宜的共培养条件为芦荟外植体浸泡在含有农杆菌的液体共培养基中半小时后,在无菌滤纸上、24℃、10h光照共培养3天;EHA105农杆菌菌系对芦荟茎部细胞的侵染能力明显强于C58C1,EHA105侵染后GUS基因瞬时表达率达到了80.0%左右,而C58C1侵染后GUS基因瞬时表达率只有30.0%左右。G418用于筛选抗性再生芽和抗性植株的适宜浓度为10.0～25.0mg/L。PCR和Southern blotting检测证实外源基因已成功整合到芦荟基因组中,转化效率为0.9%,单拷贝整合占80.0%,2～3拷贝整合占20.0%,ELISA检测证明外源基因已在转基因芦荟中稳定表达。综上所述,初步建立了农杆菌介导转化芦荟的技术体系,为利用基因工程途径改良芦荟奠定了基础。     

Relations between carbon dioxide fluxes and environmental factors of Kobresia humilis meadows and Potentilla fruticosa meadows

Carbon dioxide fluxes of Kobresia humilis and Potentillafruticosa shrub meadows,two typical ecosystems in the Qinghai-Tibet Plateau,were measured by eddy covariance technology and the data collected in August 2003 were employed to analyze the relations between carbon dioxide fluxes and environmental factors of the ecosystems.August is the time when the two ecosystems reach their peak leaf area indexes and stay stable,and also the period when the net carbon absorptions of Kobresia humilis and Potentilla photo flux densities (PPFD),the carbon dioxide-uptake rate of the Kobresia humilis meadow is higher than that of the Potentilla fruticosa shrub meadow;where the PPFD are rates of the two ecosystems declined as air temperature increased,but the carbon dioxide uptake rate of the Kobresia humilis meadow decreased more quickly (-0.086) than that of the Potentilla fruticosa shrub meadow (-0.016).Soil moistures exert influence on the soil respirations and this varies with the vegetation type.The daily carbon dioxide absorptions of the ecosystems increase with increased diurnal temperature differences and higher diurnal temperature differences result in higher carbon dioxide exchanges.There exists a negative correlation between the vegetation albedos and the carbon dioxide fluxes.     

Characteristics of the microbial community in rhizosphere of Camptotheca acuminata cultured with exotic invasive plant Eupatorium adenophorum

The traditional culture-dependent plate counting and culture-independent small-subunit-ribosomal RNA gene-targeted molecular techniques, Single-Strand Conformation Polymorphism (SSCP) and ter-minal Restriction Fragment Length Polymorphism (tRFLP) combined with 16S rDNA clone library were adopted to investigate the impacts of secretion from Camptotheca acuminata (abbreviated to Ca) roots on the quantities and structure of eukaryotic microbes and bacteria in the rhizosphere, and the possi-bility that Ca controls exotic invasive plant Eupatorium adenophorum (Ea). The counting results indi-cated that the number of bacteria increased in turn in rhizospheres of Ea, Ca-Ea mixed culture and Ca, while that of eukaryotic microbes decreased. PCR-SSCP profiles showed eukaryotic microbial bands (corresponding to biodiversity) in rhizosphere of Ea were more complex than those of Ca and CE. Meristolohmannia sp., Termitomyces sp. and Rhodophyllus sp. were the dominant populations in the rhizosphere of Ca. Bacterial terminal restriction fragments (TRFs) profiles showed no difference among three kinds of rhizospheres, and the sequences of the 16S rDNA clone library from Ca rhizospheres were distributed in 10 known phyla, in which phylum Proteobacteria were the absolute dominant group and accounted for 24.71% of the cloned sequences (δ-Proteobacteria accounted for up to 17.65%), and phyla Acidobacteria and Bacteroidetes accounted for 16.47% and 10.59% of the cloned sequences, respectively. In addition, high performance liquid chromatography detected a trace amount of camp-tothecin and hydroxycamptothecin in the rhizospheric soil of Ca and CE, but examined neither camp-tothecin nor hydroxycamptothecin in rhizospheric soil of Ea. Therefore, invasion and diffusion of Ea evidently depended on distinguishing the eukaryotic community structure, but not on that of the bac-terial pattern. Ca was able to alter the eukaryotic community structure of invasive Ea by secreting camptothecin and hydroxycamptothecin into rhizospheres, and may benefit the control of overspread of Ea. This study provided theoretical evidence for rhizospheric microbial aspects on substituting Ca for Ea.     

Phosphorylation modulates the local conformation and self-aggregation ability of a peptide from the fourth tau microtubule-binding repeat

Phosphorylation of tau protein modulates both its physiological role and its aggregation into paired helical fragments, as observed in Alzheimer's diseased neurons. It is of fundamental importance to study paired helical fragment formation and its modulation by phosphorylation. This study focused on the fourth microtubule-binding repeat of tau, encompassing an abnormal phosphorylation site, Ser356. The aggregation propensities of this repeat peptide and its corresponding phosphorylated form were investigated using turbidity, thioflavin T fluorescence and electron microscopy. There is evidence for a conformational change in the fourth microtubule-binding repeat of tau peptide upon phosphorylation, as well as changes in aggregation activity. Although both tau peptides have the ability to aggregate, this is weaker in the phosphorylated peptide. This study reveals that both tau peptides are capable of self-aggregation and that phosphorylation at Ser356 can modulate this process.     

High performance liquid chromatography with ultraviolet detection for the determination of SYUIQ-5, a novel telomerase inhibitor for cancer therapy: application to an enzyme kinetic study in rat liver microsomes

A sensitive assay for the determination of SYUIQ-5, a novel telomerase inhibitor and anti-tumor drug, in rat liver microsomes was developed by using high-performance liquid chromatography with ultraviolet detection. SYUIQ-5 was incubated in vitro with liver microsomes from rats pre-treated with control vehicle, beta-naphthofIavone, phenobarbital, 20% ethanol or dexamethasone. The analytes were extracted with diethyl ether and separated a C(18) 5-microm analytical column. Elution was conducted with 30 mM dipotassium hydrogen phosphate (pH 8.0)-methanol-triethylamine (30:70:0.05, v/v/v) at a flow-rate of 1.0 ml/min and the detection of UV absorbance was conducted at 278 nm. Intra-day and inter-day precision and accuracy of the method were within 10%. The mean analytical recoveries of SYUIQ-5 ranged from 78.8 to 95.3%. The linearity of the calibration curve was in the range of 1.0-80.0 microM. The lower limit of quantification (LOQ) was 1.0 microM. Kinetic analysis showed that beta-naphthofIavone and dexamethasone significantly induced SYUIQ-5 metabolism, suggesting that cytochrome P450 1A and 3A are the major contributor to SYUIQ-5 metabolism in rat liver microsomes.