大肠杆菌表达系统和酵母表达系统的研究进展

由于DNA重组技术和蛋白组技术的发展与成熟,外源基因表达技术备受关注。其在生物、食品、工业以及医学领域发挥着举足轻重的作用。以原核生物细胞及真核生物细胞作为表达系统,进行目的基因序列的表达以生产蛋白疫苗、核酸疫苗和生物酶制剂等是近年来发酵工业的新型领域。原核和真核表达系统是近年来研究和应用最广泛和最成熟的外源基因表达系统。对近年来关于大肠杆菌表达系统和酵母表达系统的研究进展进行了综述。     

基于Curvelet-散射特征的图像纹理分类

在二代曲线波的基础上,提出一种旋转不变曲波特征,然后结合具有平移不变性和Lipschitz连续性的散射向量特征用于对纹理图像的分类研究.通过系统分析以及严格实验可以得出,旋转不变曲波纹理特征优于广泛使用的Gabor纹理特征,且Curvelet-散射组合特征在纹理分类上具有很高准确率以及计算纹理特征的效率,和单一的散射特征相比,具有一定的优势.     

产甘油假丝酵母产甘油关键酶基因的克隆、测序及植物表达载体的构建

用PCR的方法,从产甘油假丝酵母WL2002—5中扩增出了产甘油关键酶3-磷酸甘油脱氢酶（glycerol 3-phosphate dehydrogenase）和3-磷酸甘油磷酸酶（glycerol 3-phosphate phosphatase）的基因GPD和GPP。对这两个基因测序,发现基与酿酒酵母（5accharomyces.cereuisiae）的GPD、GPP基因的相似性达99％。并构建了其在植物中的表达载体。     

泡桐属叶毛类型及对丛枝病的抗性

调查研究结果认为泡桐属叶毛类型有单枝毛、腺毛、叉状毛和树状毛4大类型.各类又有长柄、短柄或无柄之别.叶背有无叶毛和叶毛类型的不同对丛枝病的抗性有很大差异.叶背无毛或毛非常稀少对丛枝病高度感染,叶背毛为无柄（或几无柄）树状毛、短柄叉状毛和短柄、腺细胞小并无粘性腺毛的泡桐感病,叶背为不同类型的混合毛亦感病,但感病程度随长柄和短柄毛的比例不同而有所差异.叶背毛为较稠密的长柄树状毛、长柄叉状毛、长柄单枝毛和长柄、腺细胞大的粘性腺毛的泡桐为高度抗病.抗病的原因是抗传毒介体昆虫.     

Mutated sodium channel genes and elevated monooxygenases are found in pyrethroid resistant populations of Sri Lankan malaria vectors

The present status of pyrethroid resistance in vectors of malaria; Anopheles culicifacies and Anopheles subpictus, was tested in two malarious Districts, Anuradhapura and Trincomalee, of Sri Lanka. Both species were resistant to permethrin and susceptible to cypermethrin and cyfluthrin. An. subpictus were resistant to deltamethrin. λ-Cyhalothrin and etofenprox resistance was shown only by Anuradhapura An. subpictus. Although there were no differences among the populations for esterase and glutathione S-transferase activities, increased monooxygenase levels were found among Trincomalee populations. The voltage-gated sodium channel gene, the target site gene of pyrethroids, was partially sequenced to screen for mutations previously associated with insecticide resistance. The classic leucine to phenylalanine substitution, TTA to TTT, was detected in An. subpictus. It appears that both kdr type and monooxygenase resistance underlie pyrethroid resistance in these two malaria vectors of Sri Lanka.     

Detection and identification of the phytoplasma associated with pear decline in Taiwan

Pear decline (PD) is an important phytoplasmal disease that occurs mainly in Europe and North America. In 1994, pear trees exhibiting symptoms typical of PD disease were observed in orchards of central Taiwan. The sequence of 16S rDNA and 16S–23S rDNA intergenic spacer region (ISR) of the causative agent of pear decline in Taiwan (PDTW) were amplified with polymerase chain reaction (PCR) using a DNA template prepared from the diseased leaves. Sequence analysis of 16S rDNA revealed that the PDTW agent was closely related to the phytoplasmas of the apple proliferation group that cause diseases in stone fruits, pear and apple. Consistent with the result of 16S rDNA sequence analysis, sequence analysis of the 16S–23S rDNA ISR and putative restriction site analyses of 16S rDNA and 16S–23S rDNA ISR sequences provided further support for the view that the PDTW phytoplasma causing pear decline in Taiwan may represent a new subgroup of the apple proliferation group. According to the rDNA sequence of PDTW phytoplasma, two specific PCR primer pairs, APf2/L1n and fPD1/rPDS1, were designed in this study for the detection of the etiological agent in pear trees and insect vectors. Based on the sequence analyses of the PCR-amplified fragments, two species of pear psyllas, Cacopsylla qianli and Cacopsylla chinensis, were found to carry PDTW phytoplasma.     

THE INFLUENCE OF TYLOSES ON THE MANUFACTURE OF MATCHES

This article deals with the results of time studies of pruning P. radiata from 22 ft. to 35 ft. with pole saws. The influence on pruning time of mean diameter and number of branches removed in the pruning operation, number of cones removed and time of day is investigated and a multiple regression equation, expressing the relationship between pruning time and these variables, is computed. A taper table is prepared and used to investigate the effect of pruning on the formation of knot-free timber. The economics of high-pruning is discussed.     

甲病毒载体的研究进展

甲病毒属于披膜病毒科,是一类有包膜的单股正链RNA病毒。近些年来,国内外有关甲病毒载体的研究非常活跃,其已被用于疫苗研究、基因治疗以及分子生物学等研究领域。基于甲病毒载体的构造原理,将其分为三类,分别为复制完全型载体、复制缺陷型载体和DNA/RNA载体。就这三类载体的改造过程进行了探讨,并对这三类载体的特点及其应用研究进展等方面进行了阐述,以期为开发出更安全、更有效的甲病毒载体提供参考。     

法夫酵母整合型表达载体的构建

为了建立法夫酵母虾青素代谢途径研究和分子育种的技术体系,构建了法夫酵母的整合型表达载体.通过测定法夫酵母对G418的抗性来确定抗性筛选物的质量浓度,以来源于法夫酵母本身的rRNA基因为基因同源重组片段,利用法夫酵母肌动蛋白启动子和甘油醛-3-磷酸脱氢酶（gpd）启动子,构建了携带G418抗性基因的整合型载体pMD-18spakta和pMD-18spgktg.结果表明：法夫酵母对20 μg/mL质量浓度的G418敏感,将构建的载体转化法夫酵母菌株后,筛选得到了能够在含有G418的培养基上生长的转化子;利用PCR的方法检测到转化子中存在的抗性基因.将筛选得到的阳性菌株连续传代培养10次后,发现该菌株的G418抗性仍然存在;以总DNA为模板,用PCR的方法仍可检测到G418抗性基因.说明已经构建得到了遗传稳定性良好的法夫酵母整合型表达载体,构建的质粒pMD-18spakta和pMD-18spgktg可作为法夫酵母整合载体应用于法夫酵母的DNA重组实验.     

基于BMV特征的西瓜成熟度无损检测方法

针对西瓜成熟度无损测定的难度较大这一问题,提出了一种基于音频响应频带幅值向量（BMV）特征的西瓜成熟度无损检测方法。搭建了一套简单的音频采集平台,检验了BMV音频特征与西瓜成熟度的相关性,并与4种已用于西瓜无损检测的音频特征进行了比较;测定了不同打击力度对音频响应和BMV的影响;使用PNN算法对2个品种西瓜的BMV样本进行了成熟度检测。试验结果表明：经过音频特征间的比较,BMV与西瓜成熟度相关性最高,并且打击力度对特征的影响较小,整套算法对2个品种的成熟度检测准确度较高。