37 resultados para Phi Kappa Psi.
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From St15 micro-carbon deep drawing steel sheets, two sets of samples with (r) over bar variant and Deltar constant, and (r) over bar constant and Deltar variant, were selected to carry out texture measurement and ODF analysis. A description of the texture characteristics and an investigation on the effect of the main textures on the (r) over bar and Deltar values were given. The results show that in the tested steel sheets no desired gamma < 111 > parallel to ND orientation line appears but gamma' orientation line located at <(<Psi>)over bar>=0-90 degrees, theta =19 degrees and phi =45 degrees, and L orientation line located around gamma < 111 > parallel to ND orientation line which spirally rotates from Psi =0 degrees, theta =54.7 degrees and phi =62.7 degrees to Psi =90 degrees, theta =40 degrees and phi =45 degrees occur. Among them, the L orientation line has a main influence on the (r) over bar value and the stronger the texture density, the higher the (r) over bar value is, but is somewhat detrimental to the Deltar value; at the same time, the gamma' orientation line has a major effect on the Deltar value in an opposite way, but is somewhat deteriorative to the (r) over bar value. A strong L orientation line superposed by a relatively strong gamma' orientation line may produce fine (r) over bar and Deltar values.
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Sapphire crystals, 140 mm in diameter and 90 turn in height, have been grown by temperature gradient techniques (TGT). The growth direction of the boule was fixed by means of Lane X-ray diffraction. A prominent 204 nm absorption band in TGT-Al2O3. which does not appear in single crystals grown by Czochralski method has been studied. Analysis further substantiates the F-center model of this band. Two relatively weaker bands absorbing at 232 nm and 254 nm were ascribed to F+ centers. F-type centers concentration was determined using Smakula's equation. (c) 2005 Elsevier B.V. All rights reserved.
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在植物中大多数功能基因是以基因家族的形式存在的,而基因重复则是基因家族的一种重要的进化方式。很多基因往往是由重复事件产生形成不同的拷贝,进而分化形成基因家族。谷胱甘肽转移酶(GSTs)是一类古老、庞大、行使解毒、抗逆、信号转导等多种功能的一个基因家族。本研究以栽培水稻(Oryza sativa ssp. japonica c.v. Nipponbare)为研究材料,以栽培水稻的Phi类GST的5个基因(OsGSTF3、OsGSTF6、OsGSTF14、OsGSTF15、OsGSTF16)为研究对象,分析了它们的系统发生和起源历史、不同组织的差异性表达、编码蛋白质的功能差异等问题,探讨了基因重复后5个基因的功能变化,主要结果如下: 1. OsGSTF3、OsGSTF14、OsGSTF15、OsGSTF16由串联重复产生,而OsGSTF6则由DNA转座产生;它们起源时间早在稻属(Oryza)分化之前。 2. 对水稻不同部位组织的RT-PCR结果表明这5个基因在水稻中的特异性表达组织部位有较大差异:OsGSTF3基因在叶、叶鞘、茎、根4个部位均有大量表达;OsGSTF6基因仅在叶中有表达;OsGSTF14基因在叶鞘、茎2个部位中有表达;OsGSTF15基因在茎、根2个部位中有表达;OsGSTF16则在叶、茎、根3个部位中有表达。 3. 将这5个基因连接原核表达载体PET30a并转化大肠杆菌BL21(DE3),获得了高表达菌株。将表达菌株进行大量表达,表达形式分析显示OsGSTF3蛋白是可溶性表达,而其余4个蛋白以包涵体的形式表达。通过亲和层析获得了纯化的OsGSTF3融合蛋白,OsGSTF3融合蛋白对底物CDNB和NBD-Cl具有高活性,酶动力学分析显示OsGSTF3融合蛋白对GSH与NBD-Cl有较高的亲和力,热力学分析显示该蛋白在40℃以下是热稳定的。通过对包涵体进行洗涤、亲和层析获得了纯化的OsGSTF6、OsGSTF14、OsGSTF15、OsGSTF16的融合蛋白,OsGSTF14融合蛋白对NBD-Cl有微弱活性,OsGSTF15融合蛋白对NBC有较高的活性,而没有检测到OsGSTF6与OsGSTF16融合蛋白的活性。
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本文报告了以下几点研究所结果 1、NaCl, K2SO4等几种盐对菠菜叶绿体和PSI粒的甲基紫精光还原速率都有明显的促进作用。 2、以上几种盐都能改变叶绿体和PSI粒的低温荧光发射光谱中不同的荧光发射峰之间的比值。但是PSI粒低温荧光光谱的变化是和叶绿体低温荧光光谱的变化是不同的。 3、胰蛋白酶予处理并不能消除盐对叶绿体甲基紫精光还原反应的促进作用,相反地,却能提高盐的促进作用的灵敏度。 4、胰蛋白酶予处理也不能改变盐对叶绿体和PSI粒的低温荧光光谱的影响。 本文根据以上实验结果并结合前人的工作,对以上实验结果之间的内在联系进行了讨论,并试图说明盐在以上实验过程中的作用。
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一、实验证明了Cd H、Mg“在小麦类囊体膜上色素蛋白复合体的解聚和再聚合过程中,具有不同的作用。因此,二阶阳离子对激发能在光系统间的分配调节作用,可能不能仅仅用“静电现象”(Barber(1980))去解释。分析表明,在Ca2+作用下与PSII内周天线CP-47,GP-43多肽结合的L H C II和LHClb是来自间质膜区的PS I系统的。从PSI移到P S II的捕光色素蛋白,增加了PSII的捕光截面,从而促进了激发能有利于PsII分配。 二、Ca2*、Mg2+对小麦和菠菜类囊体膜光谱性质的影响有所差异。Ca2+对小麦类囊体膜光谱性质的影响还可以随着介质中Ca2+的消除而消除。同小麦类囊体膜相比,菠菜PSII以及LHCII更为集中在基粒区域,这可能是菠菜类囊体膜强Fv以及高F888/F735,F89H/F735比值的原因。因此,Ca2+,HgH对激发能在光系统间分配的调节作用是依赖于光系统间激发能及天线色素蛋白的分配状况的。 三、对菠菜叶中分离的PSII-RC: D1-D2-cyt b55g复合物进行的低温荧光发射光谱的研究表明,这一复合物可能具有F681和F684两种波长的低温荧光发射,但它们通常并不是同时存在,而是取决于Ca-670与Ca-680 Chla分子的相对含量的。PSII-RC内周无线GP-47,GP-43多肽的存在是D1-D2-cyt b559复合物低温荧光发射红移的原因;而D1一D2cyt b559复合物的不稳定性则与其低温荧光发射的蓝移现象有关。 从蕹菜叶中分离的Dl—D2-cyt b559复合物的F 381低温荧光发射也是由其相对含量较高的C.i-6 7 0 Chla分子的存在决定的。对蕹菜D 1一D 2-cyt b559复合物中的分析还表明,F 681的低温荧光发射直接来源于Di/D2复合物,而415nm处相对较强的吸收,则可能主要是与Pheo的存在有关的。 四、多肽分析与光谱分析的对照表明,CP-26内周天线多肽可能是PSII中F695低温荧光发射的真正来源。 五、实验分析了蔗糖密度离心分离的LHClI和PSI粒。结果排除了CP-27多肽(以及CP,一2 5,GP-47,CP -4 3多肽)具有F695低温荧光发射的可能,因此支持了CP-26多肽是PSII中F695低荧光发射来源的看法。对PsI粒的分析表明,P700的存在可能是与PSI-RC中较大的Sub-I亚基相联系的。 六、根据以上的研究结果,提出了PSIPSII在类囊体膜上的结构模式,并对其内容进行了分析和讨论。
Resumo:
从菠菜叶绿体中分离提纯PSI粒及其捕光天线色素蛋白复合物LHCI,对其光谱特性进行分析。对PSI粒中色素和蛋白的光破坏进程,并对外加组氨酸、Triton,以及温度对PSI粒光破坏的影响等进行了比较系统的研究,以探讨PSI破坏的机理。其主要结果如下: 1. 对PSI粒和LHCI色素蛋白复合物的荧光光谱的研究,发现PSIChlb所吸收的光能主要传递给LHCI中的“长波组分”(吸收波长大于P700的Chla)。 2. 在PSI粒光破坏进程的研究中发现,Chla中吸收波长较长的组分首先发生光破坏;位于PSI粒外围的LHCI上的Chlb,也容易受到光破坏;Car先于Chlb发生光破坏。在光照处理过程中,PSI天线色素蛋白复合物LHCI多肽降解程度大于反应中心多肽组分(PsaA,PsaB)的降解,其中LHCI-680首先由于光破坏而发生降解。PsaD也是容易受到光破坏而发生降解的一个多肽。另外,还发现在长时间光照后有蛋白聚合现象发生。 3. 在PSI粒中外加单线态氧的淬灭剂组氨酸,分析不同光强光照处理过程中组氨酸对PSI粒中色素和多肽光破坏的保护作用,发现外加组氨酸对强光照(2300μEm-2s-1)引起的叶绿素光吸收减少和CD信号减弱的有效抑制表现出一个明显的延迟期,但对强光诱导的荧光产量下降的效应却能立即表现出来;在强光照前期和弱光照(300μEm-2s-1)条件下,组氨酸不能抑制PSI粒的光吸收下降。另外,外加组氨酸除了对反应中心多肽有光保护作用以外,对PSI其它多肽也有显著的保护作用。 4. 用不同浓度的Triton处理PSI粒,发现较低浓度的Triton可以增大叶绿素的光吸收和PSI粒的荧光产量,而不对PSI粒的多肽组成造成影响;当Triton浓度达到一定的程度时,虽然不会影响PSI粒的多肽组成,但是会使其光吸收减少,荧光产量下降;而当Triton浓度过高时,PSI粒的多肽会发生降解现象,同时其光吸收和荧光产量也迅速下降。Triton浓度较低时,PSI粒光破坏的程度随Triton浓度的增大而增大,当Triton浓度增大到一定的程度时,PSI粒的光破坏程度同Triton浓度不再呈明显的正相关。 5. 对PSI粒进行不同温度的热处理,其结果表明:温度较低(20 ℃~40 ℃)的热处理对PSI粒的多肽和叶绿素光吸收的影响程度很小,照光后不同温度热处理过的PSI粒光吸收减少和多肽降解的程度相近;温度较高(50 ℃~60 ℃)的热处理会对PSI粒的结构产生影响,使之稳定性减小,对光处理更敏感;温度更高(大于70 ℃)的热处理会破坏PSI粒的结构,引起多肽组分的降解。另外,不同的多肽对热处理的敏感性显著不同。 6. 低温(4 ℃)和常温(20 ℃)下PSI粒光破坏的比较发现,室温下PSI粒的光破坏程度明显大于低温下光破坏的程度,表明光处理过程中温度会影响到PSI粒光破坏的程度。 通过上述的研究结果,分析了PSI粒光破坏过程中色素和蛋白的变化及其外界因子的影响,对PSI粒光破坏的机制进行了初步的探讨。
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Defensins are a group of cationic antimicrobial peptides which play an important role in the innate immune system by exerting their antimicrobial activity against pathogens. In this study, we cloned a novel beta-defensin cDNA from medaka (Oryzias latipes) by rapid amplification of cDNA ends (RACE) technique. The full-length cDNA consists of 480 bp, and the open reading frame (CRF) of 189 bp encodes a polypeptide of 63 amino acids (aa) with a predicted molecular weight of 7.44 kDa. Its genomic organization was analyzed, and Southern blot detection confirmed that only one copy of beta-defensin exists in the medaka HNI strain. RT-PCR, Western blot and immunohistochemistry detections showed that the beta-defensin transcript and protein could be detected in eyes, liver, kidney, blood, spleen and gill, and obviously prevalent expression was found in eyes. Antimicrobial activity of the medaka beta-defensin was evaluated, and the antibacterial activity-specific to Gram-negative bacteria was revealed. Furthermore, the lipopolysaccharide (LPS), a major component of the outer membrane of Gram-negative bacteria, was demonstrated to be able to induce about 13-fol up-regulation of the beta-defensin within first 12 h. In addition, promoter and promoter mutagenesis analysis were performed in the medaka beta-defensin. A proximal 100 base pair(bp) sequence (+26 to -73)and the next 1700 bp sequence (-73 to -1755) were demonstrated to be responsible for the basal promoter activity and for the transcription regulation. Three nuclear factor kappa B (NF-kappa B) cis-elements and a Sp1 cis-element were revealed by mutagenesis analysis to exist in the 5' flanking sequence, and they were confirmed to be responsible for the up-regulation of medaka beta-defensin stimulated by LPS. And, the Sp1 cis-element was further revealed to be related to the basal promoter activity, and transcriptional factor II D (TFIID) was found to be in charge of the gene transcription initiation. All the obtained data suggested that the novel medaka beta-defensin should have antimicrobial activity-specific to Gram-negative bacteria, and the antibacterial immune function should be modulated by NF-kappa B and Sp1. (C) 2008 Elsevier Ltd. All rights reserved.
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The glutathione S-transferases play important roles in the detoxification of microcystin. Core-sequences of three classes of GST (mu, kappa and rho) were cloned from goldfish (Carassius auratus L) i.p. injected with cyanobacterial crude extract at two doses (50 and 200 mu g MC-LReq kg(-1) BW). The relative changes of the mRNA abundance in liver, kidney and intestine were analyzed by real-time PCR. The transcription of GST mu was inhibited in intestine at both doses and the transcription of GST kappa was inhibited from 12 to 48 h in kidney at both doses. The decreased transcription of GST rho was detected in all three organs at the high dose. It is suggested that transcription inhibition of GST rho might be significant in MCs toxicity at higher toxin concentration in omnivorous freshwater fish. Alteration in transcription of GSTs stimulated by MCs implicates an increased health risk to fish. (C) 2008 Published by Elsevier B.V.
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A fish cell line, fathead minnow (FHM) cell, was used to investigate the alteration of mitochondrial dynamics and the mechanism of apoptosis under Rana grylio virus (RGV) infection. Microscopy observations, flow-cytometry analysis and molecular marker detection revealed the apoptotic fate of the RGV-infected cells. Some typical apoptotic characteristics, such as chromatin condensation, DNA fragmentation and mitochondrial fragmentation, were observed, and significantly morphological changes of mitochondria, including size, shape, internal structure and distribution, were revealed. The mitochondria in RGV-infected cells were aggregated around the viromatrix, and the aggregation could be blocked by colchicine. Moreover, the Delta psi m collapse was induced, and caspase-9 and caspase-3 were activated in the RGV-infected cells. In addition, NF-kappa B activation and intracellular Ca2+ increase were also detected at different times after infection. The data revealed the detailed dynamics of mitochondrion-mediated apoptosis induced by an iridovirus, and provided the first report on mitochondrial fragmentation during virus-induced apoptosis in fish cells.
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The storage of photoexcited electron-hole pairs is experimentally carried out and theoretically realized by transferring electrons in both real and k spaces through resonant Gamma - X in an AlAs/GaAs heterostructure. This is proven by the peculiar capacitance jump and hysteresis in the measured capacitance-voltage curves. Our structure may be used as a photonic memory cell with a long storage time and a fast retrieval of photons as well.
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The N ∗(1535) resonance contributions to the pn → dφ reaction are evaluated in an effective Lagrangian model. The π-, η-, and ρ-meson exchange are considered. It is shown that the contributions from π- and ρ-meson exchange are dominant, while the contribution from η-meson exchange is negligibly small. Our theoretical results reproduce the experimental data of both total cross section and angular distribution well. This is more evidence that the N ∗(1535) resonance has a large s ¯s component leading to a large coupling to Nφ, which may be the real origin of the Okubo-Zweig-Iizuka rule violation in the πN and pN reactions.