Amphibian tachykinin precursor

The precursor of amphibian tachykinin has not been found although more than 30 tachykinins have been isolated from amphibians since 1964. In this report, two tachykinin-like peptides are identified from the skin secretions of the frog, Odorrana grahami. T

Vespid chemotactic peptide precursor from the wasp, Vespa magnifica (Smith)

Despite the evolutional distance between wasp and amphibian, vespid chemotactic peptide (VCP), an important component of wasp venom, are found sharing remarkable similarities with the temporin antimicrobial peptides (AMPs) from Ranid frog, Amolops loloens

A small trypsin inhibitor from the frog of Odorrana grahami

A novel peptide inhibitor (OGTI) of serine protease with a molecular weight of 1949.8, was purified from the skin secretion of the frog, Odorrana grahami. Of the tested serine proteases, OGTI only inhibited the hydrolysis activity of trypsin on synthetic chromogenic substrate. This precursor deduced from the cDNA sequence is composed of 70 amino acid residues. The mature OGTI contains 17 amino acid residues including a six-residue loop disulfided by two half-cysteines (AVNIPFKVHFRCKAAFC). In addition to its unique six-residue loop, the overall structure and precursor of OGTI are different from those of other serine protease inhibitors. It is also one of the smallest serine protease inhibitors ever found. (C) 2008 Elsevier Masson SAS. All rights reserved.

Structure Elucidation and Theoretical Investigation of Key Steps in the Biogenetic Pathway of Schisanartane Nortriterpenoids by Using DFT Methods

Rubrifloradilactone C (4), a novel bioactive nortriterpenoid, along with four other nortriterpenoids (1-3, 5) were isolated from Schisandra rubriflora. The structure of 4 was determined by extensive NMR spectral analysis, computational evidence by using t

四种方法对鲢血清免疫球蛋白的纯化及分子量测定

采用mannan-binding protein(MBP)、TG及免疫亲和层析法和饱和硫酸铵沉淀法纯化鲢血清免疫球蛋白IgM,并比较了4种纯化方法的纯化效果.SDS-PAGE显示鲢血清免疫球蛋白的重链和轻链分子量分别为76.4 kD和27.2 kD,推算其总分子量约828.8kD.

Waterborne exposure to PFOS causes disruption of the hypothalamus-pituitary-thyroid axis in zebrafish larvae

Thyroid hormones (THs) play an important role in the normal development and physiological functions in fish. Environmental chemicals may adversely affect thyroid function by disturbing gene transcription. Perfluorooctane sulfonate (PFOS), a persistent compound, is widely distributed in the aquatic environment and wildlife. In the present study, we investigated whether PFOS could disrupt the hypothalamic-pituitary-thyroid (HPT) axis. Zebrafish embryos were exposed to various concentrations of PFOS (0, 100, 200 and 400 mu g L-1) and gene expression patterns were examined 15 d post-fertilization. The expression of several genes in the HIPT system, i.e., corticotropin-releasing factor (CRF), thyroid-stimulating hormone (TSH), sodium/iodide symporter (NIS), thyroglobulin (TG), thyroid peroxidase (TPO), transthyretin (TTR), ioclothyronine deiodinases (Dio1 and Dio2) and thyroid receptor (TR alpha and TR beta), was quantitatively measured using real-time PCR. The gene expression levels of CRF and TSH were significantly up-regulated and down-regulated, respectively, upon exposure to 200 and 400 mu g L-1 PFOS. A significant increase in NIS and Diol gene expression was observed at 200 mu g L-1 PFOS exposure, while TG gene expression was down-regulated at 200 and 400 mu g L-1 PFOS exposure. TTR gene expression was down-regulated in a concentration-dependent manner. Up-regulation and down-regulation of TR alpha and TR beta gene expression, respectively, was observed upon exposure to PFOS. The whole body thyroxine (T-4) content remained unchanged, whereas triiodothyronine (T-3) levels were significantly increased, which could directly reflect disrupted thyroid hormone status after PFOS exposure. The overall results indicated that PFOS exposure could alter gene expression in the HPT axis and that mechanisms of disruption of thyroid status by PFOS could occur at several steps in the synthesis, regulation, and action of thyroid hormones. (C) 2009 Elsevier Ltd. All rights reserved.

Plasma biochemical responses of the omnivorous crucian carp (Carassius auratus) to crude cyanobacterial extracts

Healthy crucian carp (Carassius auratus) were treated by intraperitoneal (i.p.) injection of crude cyanobacterial extracts at two doses, 50 and 200 mu g MC-LR equiv kg(-1) BW. High mortality (100%) was observed within 60 h post injection in the high-dose group. In the treated fish, activities of four plasma enzymes, alanine aminotransferase (ALT), alkaline phosphatase (ALP), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH), all showed substantial increases, with both dose and time-dependent effects. These increases of enzyme activity indicate severe impairment occurred in the liver of crucian carp over time. Plasma concentrations of energy-related biomolecules including glucose (GLU), cholesterol (CHO), triglyceride (TG), and total protein (TP) showed marked changes in the high-dose group, possibly a nutritional imbalance correlated with the liver injury caused by intraperitoneal exposure to crude cyanobacterial extracts.

Dietary phosphorus requirement of juvenile black seabream, Sparus macrocephalus

A growth trial was conducted to estimate the optimum requirement of dietary available phosphorus (P) for black seabream (Sparus macrocephalus) in indoor net cages (1.5x1.0x1.0 m). Triplicate groups of black seabream (11.45 +/- 0.02 g) were fed diets containing graded levels (0.18, 0.36, 0.54, 0.72, 0.89 and 1.07%) of available P to satiation for 8 weeks. The basal diet (diet 1), containing 0.18% available P, was supplemented with graded levels of monosodium phosphate (NaH2PO4 2H(2)O) to formulate five experimental diets. The fish were fed twice daily (08:00 h and 16:00 h) and reared in seawater (salinity, 26-29 g l(-1)) at a temperature of 28 +/- 1 degrees C. Dissolved oxygen during the experiment was above 5 mg l(-1). The specific growth rate (SGR), weight gain (WG), feed efficiency (FE) and protein efficiency ratio (PER) were all significantly improved by dietary phosphorus up to 0.54% (P<0.05) and then leveled off beyond this level. Hepatosomatic index (HSI) was inversely correlated with dietary phosphorus levels (P< 0.05). Efficiency of P utilization stabled in fish fed diets containing 0.18%-0.54% available P and then decreased dramatically with further supplementation of dietary phosphorus. Body composition analysis showed that the whole-body lipid, ash, calcium and phosphorus contents were all significantly affected by dietary available P concentration (P<0.05), however, no significance were found in whole-body calcium/phosphorus (Ca/P) ratios among all the treatments (P>0.05). Dietary phosphorus levels also affected the mineralization of vertebrae, skin and scale (P<0.05). Ca/P ratios in vertebrae and scale were not influenced by dietary P supplementation, while skin Ca/P ratio increased statistically with dietary available P levels (quadratic effect, P<0.001). The blood chemistry analysis showed that dietary available P had distinct effects on enzyme activities of alkaline phosphatase (ALP) and plasma lysozyme (LSZ), as well as contents of triacyglycerol (TG) and total cholesterol (T-CHO) (P<0.05). Broken-line analysis showed maximum weight gain (WG) was obtained at dietary available P concentrations of 0.55%. Quadratic analysis based on P contents in whole fish, vertebrae or scale indicated that the requirements were 0.81, 0.87 and 0.88%, respectively. Signs of phosphorus deficiency were characterized by poor growth, slightly reduced mineralization and an increase in body lipid content. (C) 2008 Published by Elsevier B.V.

Surface characterization study on SnO2 powder modified by thiourea

The SnO2 material prepared by sol-gel method was modified by thiourea solution in different concentrations (0.05, 0.1 and 0.2 mol dm(-3)). Then the structure and the average grain size of the SnO2 material were investigated by X-ray power diffraction. In order to understand the nature of the species on the SnO2 surfaces, the thermal gravimetric and differential thermal analyzer (TG-DTA) and IR spectra of these modified and unmodified sample were taken. The result indicates that the stability of oxygen adsorbed on thiourea-modified surface was improved and the amount of surface hydroxyl groups adsorbed on this grain surface was decreased. The thiourea adsorbed on SnO2 grain surface is translated to SO42- after sintered at 600 degrees C. SO42- species stabilize the resistance of the SnO2 sensor. (c) 2005 Elsevier B.V. All rights reserved.

杯芳烃羧酸萃取稀土、钍与含杯配合物结构研究

本文以大环化合物杯芳烃羧酸为萃取体系，系统考察稀土元素在该体系中的萃取分离性能，比较了钍与稀土元素的萃取性质差异，从而为杯芳烃羧酸在该分离领域中的应用提供一定的实验数据，此外，采用无机水热合成制备了含杯[8]芳烃的三元超分子配位聚合物并表征其结构，具体研究内容如下： 1、 合成杯芳烃并进行化学修饰得萃取剂杯芳烃羧酸，采用熔点测定、元素分析、TG-DTA、FT-IR和1H-NMR等分析方法表征，并利用两相滴定法测定了杯芳烃羧酸的基本常数。 2、 研究杯芳烃羧酸-CHCl3/RE-HCl萃取体系碱金属离子、离子强度、酸度、温度和萃取剂浓度对Eu(III)的萃取分配比影响，并分析其萃取机理。在此基础上，探索杯芳烃羧酸的协同萃取性能，发现杯[4]芳烃羧酸与伯胺N1923的ABC酸碱耦合协萃体系对轻、中、重稀土有不同的协萃能力，协萃系数与原子序数呈“双峰效应”。 3、 在萃取热力学基础上，利用层流恒界面池研究杯[4]芳烃羧酸萃取Nd(III)的动力学性质，确定了萃取反应控制模式随条件不同有所变化，化学反应在相界面上进行，并获得了萃取反应速率方程。 4、 以杯芳烃羧酸-CHCl3/Th-HCl体系研究钍的萃取性能，考察了碱金属离子、离子强度、酸度、温度和萃取剂浓度对Th(IV)的萃取影响，比较其与稀土萃取性能的差异，并在此基础上进一步研究与伯胺N1923协同萃取钍的性能，分析了协同萃取反应机制。 5、 水热合成并表征了含磺化杯[8]芳烃，2，2’-联吡啶与镍的三元超分子配合物。磺化杯[8]在该配合物中呈“双-反向锥式”构型，分子间由氢键和C-H…π相互作用将四核Ni簇连接成三维超分子结构。

聚苯乙烯-聚（左旋-乳酸）嵌段共聚物薄膜的相分离与结晶

本论文以对称的半结晶型的聚苯乙烯-聚（左旋-乳酸）（PS-b-PLLA）嵌段共聚物薄膜为研究对象，通过在不同厚度的膜中的时间相关的相行为的演变，来研究不同界面对嵌段共聚物薄膜熔融状态的相结构的影响，并以此相结构为模版来研究软硬受限下结晶对相分离的影响。 首先，我们研究了在不同厚度膜中的熔融状态的相结构。通过调控膜的厚度及退火时间，实现片层方向的转变。随着膜厚的增加，由于选择性的聚合物/基板界面及中性的聚合物/空气界面的作用下，达到平衡态后片层方向由平行向垂直转变。当膜厚大于一个周期时，同一膜厚下，随着退火时间的增加，片层方向由平行向垂直转变。片层方向在由平行向垂直的转变时，形成平行与垂直共存的混合结构。 在熔融状态下得到结晶的PLLA在表面对称润湿的平行片层，以这种结构为模版，研究了系留在PS基板上的PLLA单层的结晶，以及结晶对相分离结构的影响。从有序的熔融状态结晶后，形成了上下非晶中间结晶的“三明治”结构，结晶结构为α晶型正交晶系，结晶分子链垂直于界面。当Tc ≤ Tg,PS, 时，由于分子链的活动性较差，而且 PS与PLLA具有相近的表面能，结晶诱导了垂直片层的形成。当Tc > Tg,PS, 由于分子链的活动性较强，没有形成垂直片层。 以中性的聚合物/空气界面作用下形成的垂直片层为模版，研究了软硬受限条件下结晶对垂直片层结构演变的影响。硬受限下，结晶没有破坏相分离结构，在微相分离的垂直片层中受限结晶，结晶后片层周期增加。软受限下，非晶的PS分子链的活动性较强，结晶破坏了原有的相分离结构，生成棒状结晶。由于受限，结晶结构较为特殊属于单斜晶系。 以平行与垂直片层共存的混合结构为模版，研究了结晶对此结构的影响，发现平行与垂直片层分别结晶形成不同的结晶形貌，两种结晶在形成的过程中相互影响。

端基官能化共轭齐聚物的设计与合成

和共轭聚合物相比，单分散共轭齐聚物具有结构确定、易提纯等优点，不仅是建立共轭体系结构与性能关系的最佳模型，而且是一类高纯度光电子材料，还是构造具有规整结构嵌段共聚物和超分子体系的理想构造单元。鉴于基于芴单元的共轭齐聚物与聚合物具有优异的光电性能，引入不同端基能够有效调节共轭齐聚物的性能，本论文以端基官能化齐聚芴为研究对象，设计与合成了具有不同端基结构的系列单分散齐聚芴，研究了它们基本的物理化学性质，主要成果与创新点如下： 1、利用Horner-Wadsworth-Emmons反应、Wittig反应和Heck偶联反应，交替引入极性、非极性反应端基，成功解决了发散法合成较长单分散共轭齐聚物过程中产物难以提纯的技术问题，合成了系列芴撑乙烯撑共轭齐聚物。其中，最长的齐聚物含11个芴单元，光谱外推得到的有效共轭长度可达19个重复单元。DSC和偏光显微镜研究表明，芴单元数大于5的齐聚物可形成向列型液晶相。含7个芴单元以上的齐聚物可用于制备有机发光二极管，含11个芴单元的齐聚物电致发光效率是相应聚合物的5倍。 2、通过Hagigara-Sonogashira偶联、Diels-Alder环加成等反应合成了一系列端基为刚性的苯乙炔基和五苯基苯的单分散齐聚芴。但典型Scholl反应条件不能实现完全氧化脱氢，获得六苯并晕苯封端的齐聚芴。光谱研究表明苯乙炔基的引入导致吸收光谱和荧光光谱有1-2 nm的红移。五苯基苯结构的引入能显著提高齐聚芴的Tg，从而提高齐聚物的形态稳定性。 3、利用Yamamoto反应，采用端基溴代的齐聚芴大分子单体聚合结合制备色谱分离，成功地制备了分子量超过20000 Da的单分散共轭聚合物，说明大分子单体聚合结合制备色谱分离制备单分散共轭聚合物是可行的。 4、通过Horner-Wadsworth-Emmons反应合成一系列端基为三苯胺乙烯撑的单分散齐聚芴，其中，最长的齐聚物含9个芴单元。光谱研究表明，随芴单元数的增加，两个三苯胺乙烯撑端基间共轭作用显著减弱，最大吸收波长蓝移；当芴的单元数≥3时，最大发射波长均位于450 nm，和聚芴和齐聚芴相比，这类共轭齐聚物的蓝光发光峰位更佳。电化学研究表明三苯胺乙烯撑单元的氧化还原过程不受齐聚芴单元长度的影响，该封端齐聚芴的HOMO能级主要是由三苯胺乙烯撑单元决定。 关键词：端基官能化，齐聚芴，单分散共轭聚合物

糠基缩水甘油醚与二氧化碳的共聚合研究

本论文采用改进的Williamson方法合成了糠基缩水甘油醚，并在稀土三元催化剂下实现了二氧化碳和糠基缩水甘油醚的共聚合反应，合成出含糠基醚侧链的共聚物。研究了各种不同反应条件如聚合时间、聚合温度、聚合压力和稀土三元催化剂与糠基缩水甘油醚比例等对聚合反应的影响，优化了聚合反应条件。通过对共聚物IR、1H-NMR和13C-NMR的研究，确定了共聚物中的碳酸酯单元含量和共聚物的结构。所得共聚物的数均分子量最高达到13万，玻璃化温度（Tg）在 -29~-30℃之间，共聚物的起始热分解温度达到245℃，比目前已经工业化的二氧化碳－环氧丙烷共聚物（PPC）的起始热分解温度高了大约60℃，本文所合成的共聚物有可能作为增韧剂改善PPC的低温脆性，以拓展PPC的使用温度区间。

SEBS、POE与异氰酸酯的接枝反应及其对PA6、PBT的增韧研究

本工作采用熔融反应接枝的方法将(3-异氰酸酯基-4-甲基)苯氨基甲酸-2-丙烯酯(TAI)引入到聚苯乙烯-b-聚(乙烯-co-丁烯)-b-聚苯乙烯三嵌段共聚物(SEBS)上，以实现SEBS的功能化。红外光谱表明TAI已经成功接枝到SEBS上。GPC测试表明接枝后SEBS具有高的分子量与宽的分子量分布。DMA分析证明，接枝后聚(乙烯-co-丁烯) (PEB)段的玻璃化转变提高。对未参与接枝的单体的分析表明，单体TAI是个不容易自聚的单体，并对接枝过程的机理进行了研究。 为了提高TAI的存储稳定性和解决反应过程中的毒性大的问题，采用己内酰胺为封端剂对TAI中的异氰酸酯进行了封端。红外光谱和核磁共振结果表明，己内酰胺封端的TAI（BTAI）中含有双键和封闭型异氰酸酯结构，不存在着活泼的异氰酸酯。红外光谱结果表明，在高温下BTAI可以重新产生活泼的异氰酸酯基团。DSC与TG/DTA研究证明，BTAI的初始解离温度大约为135 C。采用熔融反应接枝的方法将BTAI接枝到SEBS和乙烯-辛烯共聚物（POE）分子上。研究表明，接枝率随着单体含量或引发剂含量的增加而增加。接枝以后的SEBS与POE的剪切变稀行为都比未接枝的SEBS与POE要明显。 利用BTAI功能化的SEBS和POE两种弹性体，通过熔融反应共混方法制备了PA6合金。两种弹性体与PA6共混物的红外光谱和流变行为的研究表明，在反应共混中形成了新的接枝共聚物。共混物的脆断面的场发射扫描电镜照片表明，共混物形成一种海-岛结构，而反应共混物的具有更均匀的粒子分散性，更小的粒子尺寸。PA6/SEBS-g-BTAI共混的透射电镜照片说明，共混物中形成了一种以PS为核-PEB为壳的核壳结构。与相应的物理共混物相比，通过反应共混制备的PA6合金（PA6/SEBS-g-BTAI合金和PA6/POE-g-BTAI合金）的拉伸强度、杨氏模量得到了提高。两种反应共混物的缺口冲击强度得到了非常明显的提高，合金材料的缺口冲击强度可以达到1000 J/m 以上。共混物中弹性体对PA6的结晶起到了成核的作用，结晶温度提高。形成的共聚物阻碍了PA6的分子链的运动，使得PA6的结晶温度下降。 本工作还利用上述制备的POE-g-BTAI和SEBS-g-BTAI两种功能化的弹性体与聚对苯二甲酸丁二醇酯（PBT）进行共混。研究表明，在反应共混过程中PBT中的反应基团与释放出的异氰酸酯发生反应，生成了新的共聚物。通过共混物的脆断面的FESEM图片可以看到，POE与PBT的共混物中，POE以球状粒子分散在PBT中，并且反应共混物的粒子分散均匀，粒子尺寸变小。与POE/PBT共混不同的是，在PBT与SEBS共混过程中，二者形成了交错结构，而反应共混在较低含量就形成了交错结构。POE与PBT反应共混物的缺口冲击强度得到了很大的提高，冲击强度可以达到1100 J/m以上，而PBT与SEBS的反应共混物的冲击强度改变不大。相对于物理共混物，两种弹性体与PBT的反应共混物的拉伸强度与拉伸模量都得到了提高。弹性体的加入提高了PBT的结晶温度，反应共混物的结晶温度低于物理共混物的结晶温度，说明弹性体的加入起到了PBT的成核剂的作用，生成的共聚物亦阻碍了PBT的分子链的移动。 关键词：聚苯乙烯-b-聚(乙烯-co-丁烯)-b-聚苯乙烯三嵌段共聚物；乙烯-辛烯共聚物；封闭型异氰酸酯；反应加工；聚酰胺6；聚对苯二甲酸丁二醇酯