不同水分管理下稻田CH<,4>和N<,2>O的排放及其微生物学过程

大量研究表明，农田水分状况发生变化对CH<,4>排放有重大影响，水稻生长期的晒田处理不仅有利于植株生长而且能增加CH<,4>氧化，减少CH<,4>生成.但近年来注意到有利于控制CH<,4>排放的水分管理措施往往会促进N<,2>O排放，而其机理及对大气净温室效应的影响报道甚少.该文对不同水分管理下CH<,4>和N<,2>O的排放进行了定量分析并对温室效应的贡献进行了估算;同时对二种气体排放的微生物学过程进行了研究，观测了相关微生物菌群数量及田间环境因子的变化，并对不同水分处理期间的土壤理化性质对CH<,4>和N<,2>O排放及微生物数量的影响作了进一步分析，为制定综合控制稻田CH<,4>和N<,2>O的排放措施提供了科学依据.

激光诱导CH荧光在燃烧诊断中初步应用

本文以碳氢燃料燃烧过程中最为重要和关键的自由基CH为对象，采用分子光谱测温的技术，在未采用任何滤光设备的情况下，通过CH激光诱导荧光色散谱实现了对甲烷/空气的预混本生火焰中CH自由基所处位置的温度测量。同时以平面激光诱导荧光成像的手段实现了甲烷/空气的预混本生火焰中CH的荧光分布情况的研究，从而为实现CH荧光的在线测量提供实验验证和准备。

A new zirconocene complex, [{eta(5)-C5H4-C(CH2)(5)(CH2)(2)CH(CH3)(2)}2ZrCl2]

The title compound, dichlorobis{eta(5)-[1-(3-methylbutyl)-cyclohex-1 -yl]cyclopentadienyl}zirconium(IV), [ZrCl2-(C16H25)(2)], has a pseudo-tetrahedral bent-metallocene structure in which the substituted cyclopentadienyl rings are asymmetrically bonded to the central Zr atom, due primarily to the interaction between the large substituents and the Cl atoms. The molecule has local C-2 symmetry with the substituents positioned in a trans arrangement and directed towards the lateral sectors of the bent-metallocene unit.

双核铜配合物［Cu＿2（CH＿3COO）＿2C＿5H＿5NO］＿2的合成和晶体结构

以２－羟基吡啶为配体，合成了标题配合物，测定了其晶体结构。结果表明：晶体属单斜晶系Ｃ２／ｃ空间群。晶胞参数：ａ＝１．３７３５（５）ｎｍ，ｂ＝０．８６８７（３）ｎｍ，ｃ＝：１．８６３０（９）ｎｍ，β＝９３．７３（４）°，ｖ＝２．２１８１（１６）ｎｍ￣３，Ｚ＝４．结构用直接法解出。最终偏离因子Ｒ＝０．０５１。Ｃｕ－Ｃｕ间距离为０．２６３ｎｍ。

High level expression, purification, and characterization of the shrimp antimicrobial peptide, Ch-penaeidin, in Pichia pastoris

Penaeidins, members of a new family of antimicrobial peptides constitutively produced and stored in the haemocytes of penaeid shrimp, display antimicrobial activity against bacteria, and fungi. Here, a DNA sequence encoding the mature Ch-penaeidin peptide was cloned into the pPIC9K vector and transformed into Pichia pastoris. The transformed cells were screened for multi-copy plasmids using increasing concentrations of G418. Positive colonies carrying chromosomal integrations of the Chp gene were identified by phenotype and PCR. When transformed cells were induced with methanol, SDS-PAGE and Western blotting revealed the production of a similar to6100 Da recombinant CHP (rCHP) expression product. Large scale expression revealed that rCHP was produced at 108 mg/L under optimal conditions in the highest Chp-producing P. pastoris clone. The antimicrobial activities of rCHP were studied by liquid phase analysis, which revealed that rCHP exhibited activities against some Gram-negative and Gram-positive bacteria, but had a relatively low activity against some fungi. Purification of rCHP by cation exchange chromatography and subsequent automated amino acid sequencing revealed the presence of four additional amino acids (YVEF) at the N-terminus that belonged to the cleaved fusion signal peptide; these residues may account for the observed decrease in antifungal activity. Together, these observations indicate that rCHP is an effective antimicrobial peptide that can be successfully produced at high levels in the yeast, and therefore may be a potential antimicrobial candidate for practical use. (C) 2004 Elsevier Inc. All rights reserved.

Molecular cloning and expression analysis of Ch-penaeidin, an antimicrobial peptide from Chinese shrimp, Fenneropenaeus chinensis

A new member of antimicrobial peptide genes of the penaeidin family, Ch-penaeidin, has been cloned from the haemocytes of Chinese shrimp, Fenneropenaeus chinensis, by reverse transcription PCR (RT-PCR), 3'-rapid amplification of cDNA end (3'-RACE) and smart cDNA methods. The Ch-penaeidin cDNA was 655 bp and the open reading frame of the cDNA encoded a 71 amino acid peptide. Ch-penaeidin contained a putative NH2-terminal signal Sequence (1-19) followed by a mature peptide (20-71). The sequence identify with other penaeidins from Litopenaeus vannamei and Litopenaeus setiferus is between 48% and 71%. The signal sequence of Ch-penaeidin is almost completely identical to that of other penaeidins, while differing relatively in the N-terminal domain of the mature peptide. Ch-penaeidin was designated as a novel member of class penaeidin 3 according to phylogenetic analysis. The Mature peptide. with a predicted molecular weight of 5589.32 Da, and a pI of 9.77, has eight positively charged amino acids and no negatively charged amino acids. The expression and distribution of Ch-penaeidin in Unchallenged shrimps were studied by RT-PCR, Northern blot and in situ hybridisation. The results showed that the Ch-penaeidin transcripts were detected in haemocytes (granular haemocytes), heart, gill, intestine, and subcuticular epithelia of the shrimp. and that Ch-penaeidin was constitutively expressed mainly in haemocytes. (C) 2003 Elsevier Ltd. All rights reserved.