蝎毒多肽Ctry2459抗白色念珠菌机制研究

【目的】探究蝎毒多肽Ctry2459抗白色念珠菌的作用机制。【方法】采用肉汤稀释法并结合平板计数法测定蝎毒多肽Ctry2459对白色念珠菌的最小抑菌浓度和最小杀真菌浓度;通过平板计数法绘制蝎毒多肽Ctry2459对白色念珠菌的时间-杀菌动力学曲线;通过PI吸收实验检测蝎毒多肽Ctry2459对白色念珠菌细胞膜完整性的影响;通过核酸阻滞实验检测蝎毒多肽Ctry2459与核酸间是否具有结合作用;通过流式细胞技术检测蝎毒多肽Ctry2459对白色念珠菌活性氧、线粒体膜电位以及凋亡/坏死的影响。【结果】蝎毒多肽Ctry2459对白色念珠菌的最小抑菌浓度和最小杀真菌浓度分别为25μg/mL和50μg/mL。蝎毒多肽Ctry2459对白色念珠菌的杀菌作用具有时间和浓度依赖性,并可通过直接破坏细胞膜的完整性以及通过ROS介导的线粒体失能导致细胞坏死的方式杀灭白色念珠菌细胞。【结论】蝎毒多肽Ctry2459可以作为抗白色念珠菌药物研发的候选分子或者分子模板。     

紫草素对白色念珠菌的抑制作用机制

【目的】研究紫草素抑制白色念珠菌的作用机制。【方法】通过微量稀释法测定紫草素对白色念珠菌的最低抑菌浓度(MIC)和最低杀菌浓度(MFC);紫外分光光度法测定紫草素对白色念珠菌细胞膜渗透性的影响;扫描电镜观察紫草素对菌体形态的影响;激光共聚焦显微镜测定紫草素对白色念珠菌细胞内钙离子浓度的影响;卵黄平板培养基法检测紫草素对白色念珠菌的细胞膜磷脂酶活性的影响;RT-PCR检测紫草素对白色念珠菌PLB1和PLB2基因表达量的影响。【结果】紫草素对白色念珠菌有较强的抑制作用,其对白色念珠菌的MIC和MFC分别为16μg/m L和32μg/mL。紫草素能破坏白色念珠菌细胞膜的完整性,使细胞膜的通透性增加,导致细胞内DNA和RNA等大分子物质的泄漏和细胞内钙离子的流失。其中MIC的紫草素作用菌体16 h后,上清液中的DNA和RNA等大分子含量与对照组相比增加了117.32%(P0.01);细胞内的[Ca~(2+)]降低了72.02%(P0.01)。扫描电镜结果也证明了紫草素对白色念珠菌细胞膜的破坏作用。紫草素也能抑制白色念珠菌分泌磷脂酶,且呈浓度剂量依赖。其中,与对照组相比,MIC的紫草素能使白色念珠菌分泌磷脂酶的量下降56.3%(P0.01)。RT-PCR结果显示,紫草素能抑制编码磷脂酶B的基因PLB1和PLB2的表达量,其中1/2 MIC的紫草素作用白色念珠菌16 h后,与对照组相比,PLB1和PLB2基因的相对表达量分别降低了56.4%和61.4%(P0.01)。【结论】紫草素对白色念珠菌有较强的抑杀作用,其作用机制是通过破坏白色念珠菌细胞膜的完整性,增加菌体细胞膜的通透性,导致细胞内DNA和RNA等大分子的泄漏和细胞内[Ca~(2+)]的流失,最终引起菌体的死亡。而紫草素对白色念珠菌磷脂酶分泌的抑制作用,致使其不能及时维护和修复由紫草素造成的细胞膜的破坏和损伤,也是导致菌体死亡的原因。     

和厚朴酚通过ROS的积累和破坏细胞膜杀死白色念珠菌（英文）

【目的】研究在体外情况下和厚朴酚对白色念珠菌的抑制作用及其可能机制。【方法】采用微量稀释法测定和厚朴酚对白色念珠菌的最低抑菌浓度(MIC80)和最低杀菌浓度(MFC);用透射电镜观察不同浓度和厚朴酚对白色念珠菌超微结构的影响;采用Annexin V-FITC/PI染色法分析不同浓度和厚朴酚对白色念珠菌细胞凋亡的影响;用DCFH-DA染色法测定不同浓度和厚朴酚对白色念珠菌细胞内活性氧积累的影响;用JC-1染色法分析不同浓度和厚朴酚对白色念珠菌线粒体膜电位的影响;用碘化丙啶染色、考马斯亮蓝G-250染色检测和厚朴酚对白色念珠菌细胞膜通透性的影响;通过测定加入麦角甾醇后,和厚朴酚对白色念珠菌的抑制作用的变化,检测和厚朴酚对白色念珠菌细胞膜的影响。【结果】和厚朴酚对白色念珠菌具有很强的抑制作用,MIC和MFC分别为16μg/mL和32μg/mL。对白色念珠菌细胞壁、细胞膜和胞浆均有明显的影响。和厚朴酚是通过增加活性氧的产生和破坏线粒体功能来诱导白念珠菌的细胞凋亡和坏死。它也影响细胞膜的通透性,这可能和细胞壁的破坏和与麦角固醇的结合有关。【结论】和厚朴酚通过产生活性氧并伴随着一系列的细胞损伤这种复杂的机制从而对白色念珠菌产生抑制作用,使和厚朴酚成为一种潜在的抗真菌药物。     

有机栽培龙脑百里香精油对白色念珠菌体外抑菌活性的研究

【背景】白色念珠菌(Candidaalbicans)属于条件致病性真菌,可引起严重的黏膜真菌感染及全身系统性真菌感染,是导致患者高发病率和高死亡率的主要菌群之一。【目的】探究百里香精油对白色念珠菌的抑菌活性及抑制机理。【方法】测定5种百里香精油对白色念珠菌的抑菌圈直径,分析具有高抑菌活性的精油成分。在此基础上,通过扫描电子显微镜(scanning electron microscope, SEM)观察精油对白色念珠菌菌体细胞形态的影响。测定碱性磷酸酶(alkaline phosphatase, AKP)含量、胞外溶液电导率并进行碘化丙啶(propidium iodide, PI)染色分析,探究精油对白色念珠菌生物膜的形成与黏附及磷脂酶活性的影响,并通过实时荧光定量PCR法分析与白色念珠菌生物膜形成相关基因(凝集素样序列基因ALS4,从酵母型向菌丝型细胞的形态转变基因HWP1、磷脂酶基因PLB1)的表达水平,探究该精油对白色念珠菌的抑菌机制。【结果】筛选出了对白色念珠菌高度敏感的有机栽培龙脑百里香精油(Thymus vulgaris CT borneol essential oil, T...     

表达GFP/mCherry白色念珠菌的构建及其在与巨噬细胞互作中的应用

白色念珠菌(Candida albicans)被巨噬细胞吞噬的效率与被吞噬后的形态观察是研究白色念珠菌与巨噬细胞互作的重要内容。【目的】以野生型菌株SC5314为母本,构建能够表达绿色荧光蛋白(green fluorescent protein, GFP)/mCherry的白色念珠菌,应用于巨噬细胞与白色念珠菌互作的研究。【方法】通过生长与形态观察、细胞活性检测及小鼠系统性感染模型确定荧光蛋白的表达对菌株生长、形态与毒力的影响;在共培养条件下,通过流式细胞术及荧光显微镜检测巨噬细胞的吞噬率及白色念珠菌的形态变化。【结果】构建的菌株在表型上与野生型菌株一致,并可用于在共培养下测定巨噬细胞吞噬率的流式细胞术以及观察白色念珠菌的形态变化。【结论】表达荧光蛋白的菌株为研究巨噬细胞与白色念珠菌的互作提供了新方法。     

中药蛴螬多肽Probrelin抗白色念珠菌活性研究

[目的] 研究蛴螬多肽Probrelin对白色念珠菌的抗菌活性。[方法] 采用肉汤稀释法测定蛴螬多肽Probrelin对正常菌株及临床耐药菌株的最小抑菌浓度,同时结合平板计数法测定最小杀真菌浓度;通过不同浓度多肽处理后经平板计数绘制时间-杀菌动力学曲线;通过PI吸收实验检测多肽对白色念珠菌细胞膜完整性的影响;通过核酸阻滞实验检测多肽与核酸间是否具有结合作用;通过扫描电子显微镜检测多肽对白色念珠菌形态的影响;通过结晶紫染色法检测多肽对生物膜生成及成熟生物膜的影响;通过显微镜观察多肽对白色念珠菌菌丝形成的影响;通过棋盘法检测多肽与抗真菌药物间的相互效应;通过小鼠皮下感染模型检测多肽在生理条件下的抗白色念珠菌活性。[结果] 蛴螬多肽Probrelin对正常菌株及临床耐药菌株的最小抑菌浓度均为100 μg/mL,最小杀真菌浓度为100-200 μg/mL,且对白色念珠菌的杀菌动力学具有时间和浓度依赖性;该多肽以浓度依赖性的方式影响白色念珠菌细胞膜的完整性,并通过破坏白色念珠菌细胞壁的结构影响其形态,但与核酸间不具有结合作用;该多肽既可抑制白色念珠菌生物膜的形成,又可清除成熟生物膜,同时还可抑制白色念珠菌菌丝的形成;该多肽与抗真菌药物Clotrimazole间具有协同效应;在小鼠皮下感染模型中,该多肽可以有效杀灭白色念珠菌,进而抑制感染。[结论] 蛴螬多肽Probrelin对白色念珠菌具有良好的抑制杀灭活性,可以作为新的药物分子或模板分子用于抗白色念珠菌药物的研发。     

等离子体射流灭活液体中铜绿假单胞菌的研究

【目的】测定等离子射流对铜绿假单胞菌(Pseudomonas aeruginosa)的灭活效果,探究低温等离子体射流的杀菌机理。【方法】采用平板计数法测定等离子体射流的杀菌效果,荧光显微镜、透射电镜观察等离子体作用后菌体结构的变化,蛋白浓度测定和SDS-PAGE电泳检测菌液上清液中可溶性蛋白的泄漏量。【结果】等离子体射流处理铜绿假单胞菌菌液5 min,杀灭率可达到99.9%以上。透射电镜观察可见细菌菌体结构发生改变,细胞壁、细胞膜损伤破裂,细胞内容物泄露。进一步对处理铜绿假单胞菌上清液中的蛋白质含量变化进行检测,结果显示随着处理时间的增加,上清液中蛋白质含量持续增加,在2 min时达到最大值。【结论】等离子体射流可以通过破坏细胞结构造成细胞质泄露,使其丧失正常的细胞功能,从而达到快速有效地杀灭铜绿假单胞菌的效果。     

和厚朴酚通过ROS的积累和破坏细胞膜杀死白色念珠菌

[目的]研究在体外情况下和厚朴酚对白色念珠菌的抑制作用及其可能机制。[方法]采用微量稀释法测定和厚朴酚对白色念珠菌的最低抑菌浓度（MIC₈₀）和最低杀菌浓度（MFC）;用透射电镜观察不同浓度和厚朴酚对白色念珠菌超微结构的影响;采用Annexin V-FITC/PI染色法分析不同浓度和厚朴酚对白色念珠菌细胞凋亡的影响;用DCFH-DA染色法测定不同浓度和厚朴酚对白色念珠菌细胞内活性氧积累的影响;用JC-1染色法分析不同浓度和厚朴酚对白色念珠菌线粒体膜电位的影响;用碘化丙啶染色、考马斯亮蓝G-250染色检测和厚朴酚对白色念珠菌细胞膜通透性的影响;通过测定加入麦角甾醇后,和厚朴酚对白色念珠菌的抑制作用的变化,检测和厚朴酚对白色念珠菌细胞膜的影响。[结果]和厚朴酚对白色念珠菌具有很强的抑制作用,MIC和MFC分别为16 μg/mL和32 μg/mL。对白色念珠菌细胞壁、细胞膜和胞浆均有明显的影响。和厚朴酚是通过增加活性氧的产生和破坏线粒体功能来诱导白念珠菌的细胞凋亡和坏死。它也影响细胞膜的通透性,这可能和细胞壁的破坏和与麦角固醇的结合有关。[结论]和厚朴酚通过产生活性氧并伴随着一系列的细胞损伤这种复杂的机制从而对白色念珠菌产生抑制作用,使和厚朴酚成为一种潜在的抗真菌药物。     

大黄酸抗耐甲氧西林金黄色葡萄球菌的抗菌机制

【背景】耐甲氧西林金黄色葡萄球菌(Methicillin-Resistant Staphylococcus aureus,MRSA)是医院及社区常见的机会性致病菌,具有多重耐药性、高发病率和高死亡率的特点。MRSA感染已成为全球医学界的普遍难题之一。【目的】研究大黄酸对MRSA的抗菌机制。【方法】以二倍稀释法测定大黄酸对MRSA的最小抑菌浓度(Minimum Inhibitory Concentration,MIC);通过MIC测定大黄酸对MRSA动态抑菌作用;建立生物膜模型,测定大黄酸在生物膜屏障下对生物膜内存活菌的影响,并通过扫描电镜观察不同浓度大黄酸作用后的MRSA菌体形态变化;用免疫荧光染色法、荧光分析法测定大黄酸对MRSA细胞质膜去极化和细胞膜通透性的影响。【结果】大黄酸对MRSA的MIC为8μg/mL;大黄酸能对生物膜内存活菌有明显的抑制作用,而且在大黄酸作用下菌体的形态发生明显皱缩和破损,破损严重程度与浓度呈正相关;随着大黄酸浓度和作用时间的增加,荧光强度出现明显变化,细胞膜的通透性发生改变。【结论】大黄酸主要通过损伤细菌的细胞膜,从而抑制细菌的生长和繁殖。     

炭样小单孢菌产抗生素对水稻细菌性条斑病菌的抗菌作用及其机理

【背景】水稻细菌性条斑病菌为水稻细菌性条斑病的病原菌,土壤中分离到的一株具有广谱抗菌活性的炭样小单孢菌JXNU-1,其发酵产物(即抗生素JX)对植物病原菌具有较强的抑菌活性。【目的】研究抗生素JX对水稻细菌性条斑病菌的抗菌作用及其机理。【方法】采用杯碟法测定抑菌圈大小,二倍稀释法测定最低抑菌浓度、最低杀菌浓度,并且从菌体形态观察、电导率变化、培养液大分子漏出、蛋白质合成、核酸合成和膜电位变化6个方面探究其作用机理。【结果】抗生素JX对水稻细菌性条斑病菌的抑菌圈直径达18.84±0.28mm,最低抑菌浓度和最低杀菌浓度分别为1.39μg/m L和2.78μg/mL,且杀菌速度很快,作用12 h的杀菌率达100%。在抗生素JX作用下,水稻细菌性条斑病菌的细胞形态发生改变,培养液电导率、膜电位和大分子漏出量均随抗生素浓度增加而增大,但菌体蛋白质含量随着抗生素浓度增加而降低,同时,通过实时荧光定量PCR方法检测发现ef-p表达量下调。【结论】抗生素JX对水稻细菌性条斑病菌具有较强的抗菌作用,推测其抑菌机理是通过抑制菌体蛋白质的生物合成和影响细胞膜完整性而起作用。     

Chlorate as a Transport Analog for Nitrate Absorption by Roots of Tomato

Several studies have indicated that chlorate (ClO3-) and nitrate (NO3-) may share a common transport system in higher plants. Here, we compared the interactions between ClO3- and NO3-uptake by roots of intact tomato (Lycopersicon esculentum cv T5) plants. Exposure to ClO3- for more than 2 h inhibited both net ClO3- and K+ uptake, presumably because of ClO3- toxicity; consequently, subsequent measurements were conducted after short exposures to ClO3-. The apparent affinity and apparent maximum rate of absorption for net ClO3- and NO3- uptake were very similar. Interactions between ClO3- and NO3- transport were complex; 50 [mu]M NO3- acted as a mixed inhibitor of net ClO3- uptake, but 50 [mu]M ClO3- had no significant effect on net NO3- uptake, and 500 [mu]M ClO3- had no significant effect on 15NO3- influx. If the two ions share a single common high-affinity transport system, it is much more selective for NO3- than would be suggested by the similarity of net NO3- and ClO3- uptake kinetics. Our results indicate that, although NO3- may interfere with root ClO3- uptake, ClO3- is not a useful analog for the root high-affinity NO3- transport system.     

Modeling of Ni-Fe-center of Ni-CO-dehydrogenases by nickel complexes with thiaazaligands

Three new nickel(II) complexes with ligands 1,8-bis(2'-pyridyl)-3,6-dithiaoctane (Pdto) and dithiosemicarbazone of 4,7-dithiadecane-2,9-dione (DtdtzH2) of composition Ni(Pdto)(H2O)2(ClO4)2, Ni(DtdtzH2)(ClO4)2 and Ni(Dtdtz) were prepared, their molecular structures, spectral and redox-properties were studied. The possibilities of chemical reduction of Ni(Pdto)(H2O)2(ClO4)2 to nickel(I) and nickel(0) species and the reaction of nickel(I) complex with CO were shown, which may be described as the modeling of one of the stages of reactions with CO on active Ni-Fe-site of Ni-CO-dehydrogenases. It was found that Ni(DtdtzH2)(ClO4)2 reacted with (Et4N)2[Fe4S4(SBz)4] (BzSH = C6H5 CH2SH) forming adduct. In the row of studied complexes Ni(Pdto) (H2O)2(ClO4)2 may be described as the best structural model of Ni-Fe-site of Ni-CO-dehydrogenases on the redox properties.     

Syntheses and DNA-binding studies of two ruthenium(II) complexes containing one ancillary ligand of bpy or phen: [Ru(bpy)(pp[2,3]p)2](ClO4)2 and [Ru(phen)(pp[2,3]p)2](ClO4)2

Two new ruthenium(II) complexes of [Ru(bpy)(pp[2,3]p)2](ClO4)2 and [Ru(phen)(pp[2,3]p)2](ClO4)(2) (bpy=2,2'-bipyridine, phen=1,10-phenanthroline, pp[2,3]p=pyrido[2',3':5,6]pyrazino[2,3-f][1,10]phenanthroline) have been synthesized and characterized by elemental analysis and 1H NMR spectra. The calf thymus DNA-binding properties of the two complexes were investigated by UV-visible and emission spectroscopy, competitive binding experiments with ethidium bromide and viscosity measurements. The results indicate that the two complexes intercalate between the base pairs of the DNA tightly with intrinsic DNA-binding constants of 3.08 x 10(6) and 6.53 x 10(6) M(-1) in buffered 50 mM NaCl, respectively, which are much larger than 6.9 x 10(5) M(-1) for [Ru(bpy)2(pp[2,3]p)](ClO4)2 containing two ancillary ligands of bpy.     

Ligational behavior of two biologically active N-S donors toward oxovanadium(IV) ion and potentiation of their antibacterial activities by chelation to metal ions. Part III

Chelating behavior of two biologically active ligands, pyridine-2-carboxaldehyde thiosemicarbazone (PT) and pyridine-2-carboxaldehyde-(4-phenyl)thiosemicarbazone (PPT), toward oxovanadium(IV) ion has been studied. The ligands are found to react in the thioketo form (pH 2-4), yielding the complexes [VO(PT)X2](X = Cl-, Br-, ClO4-), [VO(PT)(SO4)H2O], [VO(PPT)2X]X (X = Cl-, Br-, ClO4-) and [VO(PPT)2SO4]. Reactions of [VO(PT)(SO4)H2O] and [VO(PPT)2X]X (X = Cl-, Br-, ClO4-) with a monodenate Lewis base (B) like pyridine lead to the formation of [VO(PT)(SO4)Py]H2O and [VO(PPT)2py]X2 respectively. Bonding sites of the donor molecules around the oxometal cation have been located. Nature of the EPR spectra and magnetic moment values point to the monomeric character of the complexes and suggest a distorted octahedral donor environment for the oxovanadium(IV) ion. Status of the metal-oxygen multiple bond in all the complexes has been computed in terms of the V-O(1) stretching force constant. The ligands themselves and most of their oxovanadium(IV) complexes are found to exert powerful in vitro antibacterial activities towards E. coli.     

Effects of perchlorate on the molecules of excitation-contraction coupling of skeletal and cardiac muscle

To understand the nature of the transmission process of excitation- contraction (EC) coupling, the effects of the anion perchlorate were investigated on the voltage sensor (dihydropyridine receptor, DHPR) and the Ca release channel (ryanodine receptor, RyR) of the sarcoplasmic reticulum (SR). The molecules, from rabbit skeletal muscle, were either separated in membrane vesicular fractions or biochemically purified so that the normal EC coupling interaction was prevented. Additionally, the effect of ClO4- was investigated on L-type Ca2+ channel gating currents of guinea pig ventricular myocytes, as a native DHPR not in the physiological interaction of skeletal muscle. At 20 mM, ClO4- had minor effects on the activation of ionic currents through Ca channels from skeletal muscle transverse tubular (T) membranes fused with planar bilayers: a +7-mV shift in the midpoint voltage, V, with no change in kinetics of activation or deactivation. This is in contrast with the larger, negative shift that ClO4- causes on the distribution of intramembrane charge movement of skeletal muscle. At up to 100 mM it did not affect the binding of the DHP [3H]PN200-110 to triad-enriched membrane fractions (TR). At 8 mM it did not affect the kinetics or the voltage distribution of gating currents of Ca channels in heart myocytes. These negative results were in contrast to the effects of ClO4- on the release channel. At 20 mM it increased several-fold the open probability of channels from purified RyR incorporated in planar bilayers and conducting Ba2+, an effect seen on channels first closed by chelation of Ca2+ or by the presence of Mg2+. It significantly increased the initial rate of efflux of 45Ca2+ from TR vesicles (by a factor of 1.75 at 20 mM and 4.5 at 100 mM). ClO4- also increased the binding of [3H]ryanodine to TR fractions. The relative increase in binding was 50-fold at the lowest [Ca2+] used (1 microM) and then decayed to much lower values as [Ca2+] was increased. The increase was due entirely to an increase in the association rate constant of ryanodine binding. The chaotropic ions SCN- and I- increased the association rate constant to a similar extent. The binding of ryanodine to purified RyR protein reconstituted into liposomes had a greater affinity than to TR fractions but was similarly enhanced by ClO4-. The reducing agent dithiothreitol (5 mM) did not reduce the effect of ClO4- , and 5% polyethylene glycol, with an osmolarity equivalent to 20 mM ClO4-, did not change ryanodine binding.(ABSTRACT TRUNCATED AT 400 WORDS)     

Cytotoxic activity of platinum (II) complexes with tri-n-butylphosphine. Crystal structure of the dinuclear hydrazine-bridged complex, cis,cis-[PtCl(PBu3n)2(mu-N2H4)PtCl(PBu3n) 2] (ClO4)2.2CHCl3.

A series of platinum(II) tri-n-butylphosphine complexes having the formulas cis-[PtCl2L2], NEt4[PtCl3L], [PtCl(en)L]Cl, [Pt(en)L2](ClO4)2, sym-trans-[Pt2Cl4L2], [Pt2Cl2L4](ClO4)2, trans,trans-[PtCl2L(mu-N2H4)PtCl2L] trans,trans-[PtCl2L(mu-en)PtCl2L], and cis,cis-[PtClL2(mu-N2H4)PtClL2](ClO4)2 (L = tri-n-butylphosphine; en = ethylenediamine) have been synthesized and their cytotoxic activity in vitro and in vivo has been studied. The solution behavior of the novel dinuclear diamine-bridged platinum(II) complexes has been investigated by means of UV and 31P NMR spectroscopy. For the ionic hydrazine compound cis,cis-[PtClL2(mu-N2H4)PtClL2](ClO4)2, an x-ray structure determination is reported. Crystal data: space group P2(1)/a, a = 17.803(1), b = 18.888(3), c = 12.506(3) A, beta = 107.97(2) degrees, Z = 2, R = 0.052, RW = 0.058. The platinum coordination is approximately square-planar, with the bond lengths Pt-Cl = 2.358(5), Pt-N = 2.15(1), Pt-P(trans to Cl) = 2.260(5), and Pt-P(trans to N) = 2.262(6) A. All investigated compounds were cytotoxic in vitro against L1210 cells and showed no cross-resistance to cisplatin. On the other hand, no antitumor activity was observed vs L1210 leucemia in DBA2 mice.     

An ultracytochemical study of the respiratory potency, integrity, and fate of the sea urchin sperm mitochondria during early embryogenesis

Cytochrome oxidase activity via cytochrome c, as demonstrated by the diaminobenzidine procedure, has been employed in this electron microscope cytochemical study to determine the respiratory potency, integrity and fate of the Arbacia sperm mitochondrion at fertilization and during early embryogenesis. The sperm mitochondrion remained intact and was intensely positive for cytochrome oxidase activity both during and after penetration into the egg. The mitochondrion remained highly reactive throughout zygote formation, up to the eight-cell stage. The sperm mitochondrion formed many projections and buds in the cytoplasm of immature oocytes, monospermic and polyspermic eggs, and in blastomeres. At all stages of early embryogenesis, close juxtaposition and structural contact were observed between the highly reactive sperm mitochondrion and the less reactive egg mitochondria. The results suggest that following fertilization the mitochondrion of the sea urchin spermatozoon retains some degree of metabolic autonomy within the ooplasm. The structural integrity of the paternal mitochondrion is maintained along with a functional respiratory enzyme system (cytochrome c-a3). The hypothesis that the fertilizing sperm mitochondrion may have some relevance to sea urchin development is discussed.     

ClO2处理对油桃采后生理及相关酶活性的影响

以秦光2号油桃为试验材料,研究了ClO2浸泡处理对油桃采后生理及相关酶活性的影响,结果显示:ClO2处理可以有效降低油桃呼吸强度和乙烯释放量,减少MDA的积累,降低果实组织相对电导率,显著抑制多聚半乳糖醛酸(PG)酶和纤维素(Cx)酶的活性,延缓果实硬度的下降.保持了可溶性固形物的含量,但对可滴定酸含量的影响不大.实验表明,ClO2浸泡处理对秦光2号油桃具有一定的保鲜作用.     

Ruthenium(II) polypyridyl complexes: synthesis and studies of DNA binding, photocleavage, cytotoxicity, apoptosis, cellular uptake, and antioxidant activity

Two ruthenium (II) complexes [Ru(dmb)2(APIP)](ClO4)2 (APIP=2-(2-aminophenyl)imidazo[4,5-f?][1,10]phenanthroline, dmb=4,4'-dimethyl-2,2'-bipyridine; 1) and [Ru(dmb)2(HAPIP)](ClO4)2 (HAPIP=2-(2-hydroxyl-4-aminophenyl)imidazo[4,5-f?][1,10]phenanthroline; 2) were synthesized and characterized. DNA binding was investigated by electronic absorption titration, luminescence spectra, thermal denaturation, viscosity measurements, and photocleavage. The DNA binding constants for complexes 1 and 2 were 4.20 (±0.14)×10(4) and 5.45 (±0.15)×10(4) M(-1). The results suggest that these complexes partially intercalate between the base pairs. The cytotoxicity of complexes 1 and 2 was evaluated by MTT assay. Cellular uptake was observed under fluorescence microscopy; complexes 1 and 2 can enter into the cytoplasm and accumulate in the nuclei. Apoptosis and the antioxidant activity against hydroxyl radicals (?OH) were also explored.     

Dinuclear macrocyclic polyamine zinc(II) complexes: syntheses, characterization and their interaction with plasmid DNA

The syntheses, characteristics of dinuclear macrocyclic polyamine zinc complexes and their interaction with plasmid DNA are reported. The two cyclen (1,4,7,10-tetraazacyclododecane) moieties are bridged by rigid and flexible linkages. The crystal structures of Zn2C27H43N8O15Cl4 [5c.(ClO4)3.2H2O] and Zn2C30H43N10O13Cl3 [5e.(ClO4)3.H2O] have been determined. The complexes crystallize in the monoclinic space group C2/c and P2(1)/c with the following unit cell parameters: 5c.(ClO4)3.2H2O: a=32.568(4)A, b=14.8593(17)A, c=19.443(2)A, alpha=90.00 degrees , beta=119.435(4) degrees , gamma=90.00 degrees , Dc=1.551 mg/m3, FW=956.71, F(000)=3932; 5e.(ClO4)3.H2O: a=15.807(2)A, b=16.756(2)A, c=16.161(2)A, alpha=90.00 degrees , beta=97.062(4) degrees , gamma=90.00 degrees , Dc=1.546 mg/m3, FW=988.83, F(000)=2032. The distance between the two Zn(II) ions is about 4.0 A. The structures show that two zinc ions can synergistically interact with the substrate DNA. With this novel structural characteristics, the dinuclear macrocyclic polyamine Zn(II) complexes via the synergetic effect between the two zinc ions can catalyze the cleavage of plasmid DNA (pUC18) with unprecedented speed at physiological conditions.