The comparative analysis of the energies of conjugated triple base triplets and their applications

We built 64 sets of 3D models of DNA triplex base triplets (TBT) and minimized their energies. The TBTs were divided into 32 pairs of conjugated ones on the basis of their sequence characteristic, and the energies of each pair of them were compared and analyzed, the results showed: (i) The duplex DNA of which any strand contains at least a couple of A or T, has a preference for selecting the oligodeoxyribonucleic acid (ODN) strand containing abundant T to form TBT. (ii) The duplex DNA of which any strand contains at least a couple of G or C has a preference for selecting ODN containing abundant G to form symmetric antiparallel TBT, but selecting ODN containing abundant C to form asymmetric parallel TBT. (iii) The duplex DNA of which any strand contains only one of A, T, G or C has a preference for selecting ODN containing abundant pyrimidines (T or C) to form antiparallel TBT. Additionally, two examples of TBTs applications, in designing ODN to form triplex with duplex were presented. The energy calculation result revealed that 15-TCG is the best ligand of the HIV PPT duplex. The comparative analysis of energies of the conjugated TBTs provides directive significance for designing ODN strand that is easy to form triplex in theory. (C) 2002 Elsevier Science B.V. All rights reserved.

不同培养条件对具鞘微鞘藻生物量和多糖产量的影响

国家重点基础研究发展规划(973)项目(2002CB412306); 国家自然科学基金(No.30170112); 国家自然科学基金(No.30500068)资助

圆形碘孢虫单链抗体库的筛选与阳性克隆特征分析

噬菌体抗体库已成为单克隆抗体生成的重要技术之一。本文通过用圆形碘孢虫相关抗原对已构建的鼠源免疫噬菌体展示单链组合抗体文库进行生物淘选,并对几株相对亲和力较高的阳性单克隆序列特征、相对亲和力及热稳定性等进行了分析。ELISA、间接免疫荧光及免疫印迹等进行特征鉴定。结果表明,噬菌体抗体库技术对于分离抗圆形碘孢虫不同表位抗原是可行的,将为粘体动物的抗原物质及分布、寄生虫-宿主相互关系等研究提供丰富的抗体来源。

滇池水体中微囊藻毒素含量变化与环境因子的相关性研究

本文对2003年4-12月滇池马村湾、海东湾微囊藻毒素和总磷、总氮、溶解氧、透明度、光照强度、叶绿素a、pH值、水温及微囊藻种群优势度进行了分析,讨论了以上指标在滇池马村湾和海东湾的分布和月变化情况以及与微囊藻毒素含量之间的关系．相关性分析表明马村湾、海东湾微囊藻毒素在水体中分布与总氮和氮磷比之间呈现非常显著的负相关性(P<0．01);与透明度、光照强度和微囊藻种群优势度存在显著的正相关性(P<0．05)．在影响微囊藻毒素的各因素中,运用多因素逐步回归分析得知马村湾、海东湾微囊藻毒素浓度主要南水体的总氮、

鲤鱼两个cGnRH-Ⅱ基因的发现及其在成熟个体的表达分析

促性腺激素释放激素(GnRH)是一个保守的神经十肽家族,在调节脊椎动物的性腺发育和控制性成熟中起至关重要的作用.用RACE和RT-PCR方法,从鲤鱼脑组织克隆得到两个差异的cGnRH-Ⅱ cDNAs序列,其长度分别为622,578 bp.两个cDNA编码的cGnRH-Ⅱ前体均为86个氨基酸,包括一个信号肽、cGnRH-Ⅱ十肽和一个由蛋白水解位点(Gly-Lys-Arg)连接的GnRH相关肽.内含子捕获和Southern杂交证实鲤鱼基因组中有两个cGnRH-Ⅱ编码基因,且两个基因都可能以单拷贝形式存在.鲤鱼

地木耳规模化培养的初步研究

利用跑道式培养池规模化培养地木耳,结果显示:在一定的实验条件下,地木耳群体的直径明显增大,其生长速度最高可达445.2g·m-2·d-1,并可将其它杂藻类控制在较低的水平。这是地木耳规模化培养的首次报道。

鱼粉在水产饲料中的应用研究

中国科学院创新方向性项目"集约化水产养殖高新技术及其生态调控"(KSCX2-1-04); 国家"十五"科技攻关项目"鱼用高效饲料开发技术"(2001BA505B06)

中华鳖病毒(TSV)对鱼类细胞的感染试验

将 12种鱼类培养细胞用于中华鳖病毒 ( Trionyx sinesisvirus,TSV)的体外感染试验。结果显示 ,TSV能使鲤鱼上皮乳状瘤细胞 ( EPC)、鳗鲡性腺细胞 ( EG)和草鱼卵巢细胞 ( CO)产生病变。比较了不同培养温度对 TSV感染鱼类细胞的影响以及 TSV引起鱼类细胞病变的特征。 TSV引起 3种鱼类细胞病变 ,经显微观察 ,它们具有不同的病变特征。 TSV感染细胞后 ,其 TCID5 0 在 2 0～ 30℃范围内 ,随温度的升高而增加。超微观察表明 ,从感染的鱼类培养细胞中分

我国某厂石墨电极废渣中二噁英的指纹特征

研究发现我国氯碱工业中由于采用石墨电极，产生的固体废渣中含有大量二噁英，其总浓度高达 ３７８．８５μｇ／ｋｇ，二噁英各组异构体浓度指纹的特征表现为以四至八氯代的二苯并呋喃（ＰＣＤＦｓ）为主，其中２，３，７，８位氯取代ＰＣＤＦｓ占废渣中总ＰＣＤＦｓ的８０ ％以上，而多氯代二苯并二噁英（ＰＣＤＤｓ）的浓度仅处于０．０１５ μｇ／ｋｇ水平．根据二噁英国际毒性当量因子（Ｉ－ＴＥＦ），计算出该电解废渣的毒性当量（Ｉ－ＴＥＱ）值为 ２１．６５μｇ／ｋｇ，我国电解废渣中二噁英的这种典型的“氯碱指纹”，在该氯碱工业废水排

两种人工湿地中氮、磷净化率与细菌分布关系的初步研究

研究了凤眼莲、水芹人工湿地对东湖污水中氮、磷净化率与有关细菌的空间分布的关系.结果表明:人工湿地中,植物除本身可以直接吸收含氮、磷化合物外,其根系分泌物可促进某些嗜磷、氮细菌的生长,促进氮、磷释放、转化,从而间接提高净化率.有植物的湿地系统,以上细菌数量显著高于无植物系统,且植物根部的细菌数比介质中高1～2 个数量级.在除氮机制中,植物起主导作用,而在磷的净化过程中,细菌是一个限制性因子.

Time-Dependent Oxidative Stress Responses of Crucian Carp (Carassius auratus) to Intraperitoneal Injection of Extracted Microcystins

This study was conducted to investigate time-dependent changes in oxidative enzymes in liver of crucian carp after intraperitoneally injection with extracted microcystins 600 and 150 mu g kg(-1) body weight. The results showed that activities of antioxidant enzymes, including superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase generally exhibited a rapid increase in early phase (1-3 h post injection), but gradually decreased afterwards (12-48 h) compared with the control, with an evident time-dependent effect. These zigzag changes over time contributed a better understanding on oxidative stress caused by microcystins in fish.

Cloning and expression analysis in mature individuals of two chicken type-II GnRH (cGnRH-II) genes in common carp (Cyprinus carpio)

Gonadotropin-releasing hormone (GnRH) is a conservative neurodecapeptide family, which plays a crucial role in regulating the gonad development and in controlling the final sexual maturation in vertebrate. Two differing cGnRH-II cDNAs of common carp, namely cGnRH-II cDNA1 and cDNA2, were firstly cloned from the brain by rapid amplification of cDNA end (RACE) and reverse transcription- polymerase chain reaction (RT-PCR). The length of cGnRH-II cDNA1 and cDNA2 was 622 and 578 base pairs (bp), respectively. The cGnRH-II precursors encoded by two cDNAs consisted of 86 amino acids, including a signal peptide, cGnRH-II decapeptide and a GnRH-associated peptide (GAP) linked by a Gly-Lys-Arg proteolytic site. The results of intron trapping and Southern blot showed that two differing cGnRH-II genes in common carp genome were further identified, and that two genes might exist as a single copy. The multi-gene coding of common carp cGnRH-II gene offered novel evidence for gene duplication hypothesis. Using semi-quantitative RT-PCR, expression and relative expression levels of cGnRH-II genes were detected in five dissected brain regions, pituitary and gonad of common carp. With the exception of no mRNA2 in ovary, two cGnRH-II genes could be expressed in all the detected tissues. However, expression levels showed an apparent difference in different brain regions, pituitary and gonad. According to the expression characterization of cGnRH-II genes in brain areas, it was presumed that cGnRH-II might mainly work as the neurotransmitter and neuromodulator and also operate in the regulation for the GnRH releasing. Then, the expression of cGnRH-II genes in pituitary and gonad suggested that cGnRH-II might act as the autocrine or paracrine regulator.

Design and Fabrication of AlGaN-Based Resonant-Cavity-Enhanced p-i-n UV PDs

AlGaN-based resonant-cavity-enhanced (RCE) p-i-n photodetectors (PDs) for operating at the wavelength of 330 nm were designed and fabricated. A 20.5-pair AlN/Al0.3Ga0.7N distributed Bragg reflector (DBR) was used as the back mirror and a 3-pair AlN/Al0.3Ga0.7N DBR as the front one. In the cavity is a p-GaN/i-GaN/n-Al0.3Ga0.7N structure. The optical absorption of the RCE PD structure is at most 59.8% deduced from reflectance measurement. Selectively enhanced by the cavity effect, a response peak of 0.128 A/W at 330 nm with a half-peak breadth of 5.5 nm was obtained under zero bias. The peak wavelength shifted 15 nm with the incident angle of light increasing from 0 degrees to 60 degrees.

Kinetic study of hydrolysis of xylan and agricultural wastes with hot liquid water

We investigated the kinetics of hot liquid water (HLW) hydrolysis over a 60-min period using a self-designed setup. The reaction was performed within the range 160-220 °C, under reaction conditions of 4.0 MPa, a 1:20 solid:liquid ratio (g/mL), at 500 rpm stirring speed. Xylan was chosen as a model compound for hemicelluloses, and two kinds of agricultural wastes-rice straw and palm shell-were used as typical feedstocks representative of herbaceous and woody biomasses, respectively. The hydrolysis reactions for the three kinds of materials followed a first-order sequential kinetic model, and the hydrolysis activation energies were 65.58 kJ/mol for xylan, 68.76 kJ/mol for rice straw, and 95.19 kJ/mol for palm shell. The activation energies of sugar degradation were 147.21 kJ/mol for xylan, 47.08 kJ/mol for rice straw and 79.74 kJ/mol for palm shell. These differences may be due to differences in the composition and construction of the three kinds of materials. In order to reduce the decomposition of sugars, the hydrolysis time of biomasses such as rice straw and palm shell should be strictly controlled.