有机硅橡胶固定化细胞进行的生物转化

有机硅橡胶固定化细胞进行的生物转化潘冰峰,戴学倩,冯青,李祖义（中国科学院上海有机化学研究所,２０００３２）关键词硅橡胶;白地霉;固定化细胞;生物转化近年来,有机化学领域的一个重要进展是用酶或微生物进行生物转化反应。其中研究和应用较多的是碳基还原,特...     

Sequence diversity in the amino-terminal region of the malaria-vaccine candidate serine repeat antigen in natural Plasmodium falciparum populations

The amino-terminal region of the serine repeat antigen (SERA) of Plasmodium falciparum is a major malaria-vaccine candidate. Variation in this molecule is essentially dimorphic and alleles may be grouped into the types FCR3, K1 and Honduras1. The Honduras1-type is thought to be the product of homologous recombination between FCR3 and K1 alleles. Here we have examined patterns of sequence diversity in exon II of SERA gene, which encodes most of the amino-terminal region of the antigen, in wild P. falciparum isolates from Indonesia (n=60), Myanmar (n=10) and Thailand (n=14). Among the Indonesian isolates the FCR-3 type predominated (56/60), twenty of which we characterized as novel alleles. A new K1-type allele was also found. In Myanmar, however, all isolates displayed K1-type SERA sequences, which included one new allele. The Honduras1-type was not detected in both countries. In contrast, the 14 isolates from Thailand displayed all three allelic types, with one new Honduras1-type and three new K1-type alleles. On examining the global distribution of SERA alleles by combining previously published sequence data with our results, the FCR3-type alleles predominated in Indonesia, Brazil, and Solomon Islands, but were not found in wild isolates from Myanmar and Africa. Brazil was the only area where K1-type alleles were not found. The distribution of Honduras1-type alleles seems to be mostly restricted to parasite populations from Vietnam, Thailand and Africa. In the allelic families FCR3 and K1, most diversity resulted from variation in sequence and number of octamer repeat units and of allotypes encoding the stretch of serine residues. Sequence analysis indicated that both insertions and deletions of repetitive motifs (creating variation within dimorphic allelic families) and homologous recombination between alleles belonging to different allelic families (creating Honduras1-type alleles) play a role in generating new SERA alleles. Since repeat motifs in the amino-terminal region of SERA contain epitopes recognized by parasite-inhibitory antibodies, sequence variation in exon II may represent one of the parasite's immune-evasion strategies.     

Calcium-binding proteins and development

The known roles for calcium-binding proteins in developmental signaling pathways are reviewed. Current information on the calcium-binding characteristics of three classes of cell-surface developmental signaling proteins (EGF-domain proteins, cadherins and integrins) is presented together with an overview of the intra-cellular pathways downstream of these surface receptors. The developmental roles delineated to date for the universal intracellular calcium sensor, calmodulin, and its targets, and for calcium-binding regulators of the cytoskeleton are also reviewed.© Kluwer Academic Publishers     

具超强汞富集能力基因工程菌生长情况的研究

对具超强汞富集能力的基因工程菌在重金属汞离子存在的水体中的生长状况进行了研究。实验所采用的基因工程菌由于外源基因的表达而对Hg^2 产生了一定的耐受力,而且这种耐受力经IPTG诱导后还能得到进一步的增强,耐受能力从Hg^2 浓度5mg／L提高到15mg／L。IPTG加入的时机对菌体的生长和耐受力的有效诱导是重要的。一般在OD600为0．5～0．8时加入,且加入后还应保证2h左右的诱导时间。实验结果还表明菌体在生长过程中对碳源的要求很低。     

Soap-HT-BLAST: high throughput BLAST based on Web services

SUMMARY: A high throughput Basic Local Alignment Search Tool (BLAST) system based on Web services is implemented. It provides an alternative BLAST service and allows users to perform multiple BLAST queries at one run in a distributed, parallel environment through the Internet. AVAILABILITY: It is available at http://mammoth.bii.a-star.edu.sg/webservices/htblast/index.html and at http://www.bii.a-star.edu.sg/jiren/download.html     

Occurrence of the Transition of Apical Architecture and Expression Patterns of Related Genes during Conversion of Apical Meristem Identity in G2 Pea

G2 pea exhibits an apical senescence delaying phenotype under short-day (SD) conditions; however, the structural basis for its apical development is still largely unknown. In the present study, the apical meristem of SD-grown G2 pea plants underwent a transition from vegetative to indeterminate inflorescence meristem, but the apical meristem of long-day (LD)-grown G2 pea plants would be further converted to determinate floral meristem. Both SD signal and GA3 treatment enhanced expression of the putative calcium transporter PPF1, and pea homologs of TFL1 (LF and DET), whereas LD signal suppressed their expression at 60 d post-flowering compared with those at 40 d post-flowering. Both PPF1 and LF expressed at the vegetative and reproductive phases in SD-grown apical buds, but floral initiation obviously increased the expression level of PPF1 compared with the unchanged expression level of LF from 40 to 60 d post-flowering. In addition, although the floral initiation significantly enhanced the expression levels of PPF1 and DET, DET was mainly expressed after floral initiation in SD-grown apical buds. Therefore, the main structural difference between LD- and SD-grown apical meristem in G2 pea lies in whether their apical indeterminate inflorescence medstem could be converted to the determinate structure.     

Antioxidant Capacity of Flavonoid in Soybean Seedlings under the Joint Actions of Rare Earth Element La(III) and Ultraviolet-B Stress

The dynamic state of antioxidant capacity of flavonoid was investigated for a further demonstration of alleviating the damage of the ultraviolet (UV)-B radiation in the La-treated soybean seedlings under UV-B stress. Using hydroponics culture, the effects of lanthanum on the contents of flavonoid and its ability of antioxidant under elevated ultraviolet-B radiation (280–320 nm) was studied. The results showed flavonoid content in soybean seedlings with UV-B treatment during the stress and convalescent period was increased initially and then decreased, compared with control. Membrane permeability and MDA contents increase at first (first to fifth day) and then decrease (6th–11th day). A similar change of flavonoid content and clearance of flavonoid scavenging and ·OH in soybean seedlings occurred. Flavonoid content and ability of flavonoid scavenging and ·OH in soybean seedlings with La(III) + UV-B treatment were higher than those of UV-B treatment. Meanwhile, membrane permeability and MDA contents in soybean seedlings were lower than those of UV-B treatment. Compared with control, phenylalanine content in soybean seedlings with UV-B treatment is depressed, phenylalanine content in soybean seedlings with La(III) treatment was enhanced. However, phenylalanine content in La(III) + UV-B treatment is not decreased but slightly increased, compared with UV-B treatment. It suggested that the regulative effect of La(III) of the optimum concentration on flavonoid improved the metabolism of ROS, diminished the concentration of MDA and maintained normal plasma membrane permeability, and that its protective effect against low UV-B radiation is superior to that of high UV-B radiation. The defensive effect of La(III) on soybean seedlings under UV-B stress is carried out on the layer of defense system.     

麦长管蚜对E-β-法尼烯的嗅觉行为反应

【目的】测定麦长管蚜Sitobion avenae Fabricius对E-β-法尼烯(E-β-farnesene,EβF)矿物油溶液反应的最低阈值浓度,为EβF的田间应用提供依据。【方法】观察麦长管蚜3龄若蚜对不同浓度EβF的逃逸行为和"Y"型管嗅觉行为反应。每天定时分5次(9:00,11:30,14:00,16:30和19:00)滴加10μL EβF于滤纸上,滤纸用牙签固定于麦苗盆中心,持续处理5 d。每盆麦苗处理前接1龄若蚜15头。记录成蚜翅型及2周后蚜虫总数量。【结果】随着EβF浓度升高,麦长管蚜3龄若蚜3 min内逃离数显著增加,有翅蚜比例显著增加,种群个体数量显著下降,驱避效果明显增强。EβF浓度为200 ng/μL和≥600 ng/μL使蚜虫逃离数显著增加(P0.05)。"Y"型管选择行为测试结果表明,EβF≥600 ng/μL对3龄若蚜具有极显著的驱避作用(P0.01)。与对照相比,EβF≥600 ng/μL处理极显著提高了有翅蚜比例(P0.01);EβF≥400 ng/μL极显著抑制蚜虫种群个体数量增长(P0.01),但与600 ng/μL处理差异不显著。【结论】600 ng/μL EβF矿物油溶液为麦长管蚜驱避剂的最低阈值浓度。