Expression of Anti-Lipopolysaccharide Factor Isoform 3 in Chlamydomonas reinhardtii Showing High Antimicrobial Activity

Antimicrobial peptides are a class of proteins with antibacterial functions. In this study, the anti-lipopolysaccharide factor isoform 3 gene (ALFPm3), encoding an antimicrobial peptide from Penaeus monodon with a super activity was expressed in Chlamydomonas reinhardtii, which would develop a microalga strain that can be used for the antimicrobial peptide production. To construct the expression cluster, namely pH2A-Pm3, the codon optimized ALFPm3 gene was fused with the ble reporter by 2A peptide and inserted into pH124 vector. The glass-bead method was performed to transform pH2A-Pm3 into C. reinhardtii CC-849. In addition to 8 μg/mL zeocin resistance selection, the C. reinhardtii transformants were further confirmed by genomic PCR and RT-PCR. Western blot analysis showed that the C. reinhardtii-derived ALFPm3 (cALFPm3) was successfully expressed in C. reinhardtii transformants and accounted for 0.35% of the total soluble protein (TSP). Furthermore, the results of antibacterial assay revealed that the cALFPm3 could significantly inhibit the growth of a variety of bacteria, including both Gram-negative bacteria and Gram-positive bacteria at a concentration of 0.77 μM. Especially, the inhibition could last longer than 24 h, which performed better than ampicillin. Hence, this study successfully developed a transgenic C. reinhardtii strain, which can produce the active ALFPm3 driven from P. monodon, providing a potential strategy to use C. reinhardtii as the cell factory to produce antimicrobial peptides.     

黄皮的生物学特性研究

通过本试验观察表明:黄皮[Clausena Lansium (Lour.)Skeels]的开花与温度有密切关系,温度高,开花过程短;温度低,开花过程长。花穗中的花轴增长速度也随温度升高而加快,花轴增长快,则花轴长,花穗大;反之,花轴增长速度慢,花轴短,花穗小。黄皮开花的顺序是从花穗基部第1—4个分枝开始,每个分枝则先从基部1—8个二次分枝首先开放。31℃是黄皮花粉萌发最适宜温度。在培养基中加入15—20％蔗糖或2.4—D,三十烷醇等生长调节物质,明显可提高黄皮花粉的萌发力。本试验对黄皮的物候期及植物学特性同时进行了研究。     

树木挥发物对植食性昆虫的诱导抗性

树木挥发物质对植食性昆虫取食，产卵所产生的诱导抗性是树木与昆虫的长期协同进化过程中的必然结果，树木与植食性昆虫之间发展了一套互相调节，自身开拓资源，产生生存对策的复杂相互关系，本文着重阐明了树木与植食性昆虫的互相策略，诱导抗性的生物化学基础以及诱导抗性在调节植食性昆虫种群中的重要性。     

干旱区20个紫花苜蓿品种抗旱性研究

该试验测定了20个苜蓿品种的水势、总含水量、自由水量、束缚水量、束/自比以及渗透调节物质.从植物水分生理与生化方面,测试各品种的抗旱性,并结合产草量、品质进行综合评价.从中选出5～6个抗旱性较强、产草量高、品质较好的苜蓿品种,为干旱区选择适宜的苜蓿品种提供具有实用价值的基础资料.     

A review of antimicrobial peptides: defensins and related cationic peptides

Cationic antimicrobial peptides are present throughout the plant and animal kingdoms and bear striking structural and functional similarities across species lines. They provide primitive, nonspecific means of combating a variety of bacteria, fungi, enveloped viruses, and protozoa. Some are also cytotoxic against host cells, including neoplastic cells. Cationic antimicrobial peptides may play various roles in inflammation and tissue repair. Antimicrobial peptides are found in epithelial tissues regularly exposed to microbial attack as well as in cells whose primary function is defense against potential pathogens. They constitute an important part of the nonoxidative antimicrobial arsenal of leukocytes. They are preformed and/or readily synthesized when the cells are stimulated by exposure to pathogens. They exert their effects directly by inserting into membranes of target cells and forming ion channels which increase membrane permeability; however, antimicrobial peptides can also act as opsonins to facilitate phagocytosis. Resistance to defensins is a virulence factor for organisms such as Salmonella sp. The study of cationic antimicrobial peptides is increasing our understanding of innate immunity, inflammation, and the pathogenesis of genetic diseases such as specific granule disease in humans. Therapeutic applications of antimicrobial peptides are currently under investigation.     

Aromatic Substances Inhibiting Wheat Powdery Mildew Produced by a Fungus Detected with a New Screening Method for Phylloplane Fungi

Microorganisms isolated from wheat leaf surfaces were screened for inhibition of wheat powdery mildew. A new screening method, in which wheat leaves were inoculated with Blumeria graminis f. sp. tritici and incubated with the cultured microorganisms under non-contact conditions, was developed in the present study. Using this method, 10 phylloplane fungi that inhibited wheat powdery mildew were selected from 408 microorganisms isolated from wheat leaf surfaces. Among these 10 strains, a fungus designated as Kyu-W63 had an especially strong inhibitory effect. Kyu-W63 produced white colonies without spores when cultivated on PDA. Kyu-W63 had a strong aromatic odor when being cultured. Wheat powdery mildew was suppressed even though a membrane filter with a pore size of 0.45 μm was placed between the mycelial colony and wheat leaf segment. However, when activated charcoal was introduced, Kyu-W63 did not inhibit growth of B. graminis. It was presumed that volatile substances were involved in the inhibitory effect of Kyu-W63. GC-MS analysis was used to identify two substances produced by Kyu-W63 with molecular weights of 164 and 166. Kyu-W63 also inhibited the in vitro growth of four plant pathogenic fungi other than B. graminis. Received 19 September 2001/ Accepted in revised form 7 February 2002     

花粉多糖注射剂质量标准中几个项目测定

根据中国药典对注射剂的要求,对花粉多糖的蛋白质、鞣质、树脂、草酸盐、炽灼残渣、钾离子、砷盐、重金属含量进行测定,均符合规定,达到质量标准。     

芽孢杆菌BC98-Ⅰ抗真菌物质的初步分离及特性

BC98-Ⅰ是一株分离自沤肥浸渍液的蜡状芽孢杆菌，对蔬菜、瓜类、花卉枯萎病具良好的防治效果。它分泌产生的抗真菌物质的粗提物对黄瓜、西瓜、青椒枯萎菌有很强的拮抗作用，当浓度为10mg／mL时，抑菌圈直径分别达到20．33、20．22和22．77mm。该粗提物对高温高压、紫外光和蛋白酶均不敏感。同时，它在中性偏碱(pH8～9)的条件下活性最高；在极性溶剂如水、甲醇、乙醇中溶解度大，抑菌活性高。粗提液经Sephadex G100层析后，得到了两个洗脱峰，活性物质存在于第一峰中。抑菌机制试验表明：它可造成孢子萌发率降低、菌丝生长形态异常、分支加剧并产生大量泡囊。     

Transgenic cucumber expressing an endogenous class III chitinase gene has reduced symptoms from Botrytis cinerea

A class III chitinase gene (CHI2) is induced in cucumber plants (Cucumis sativa L.) in response to infection by pathogenic microorganisms. Infection of Botrytis cinerea, causal agent of gray mold disease on cucumber, also induces CHI2 expression. To investigate whether CHI2 is involved in resistance to gray mold disease, transgenic cucumber plants were produced to overexpress the CHI2 gene. One line was analyzed in detail in terms of disease resistance. The transgenic cucumber plant (CC2) constitutively expressed CHI2 and reduced the symptoms of B. cinerea for 4 days after inoculation compared with nontransgenic plants. However, this inhibitory effect was not absolute, and CC2 eventually developed serious disease symptoms. Chitinase activity of the crude extract from CC2 leaves was higher than that from nontransgenic plants. A high-molecular-weight fraction containing CHI2 from CC2 leaves had fungistatic activity against B. cinerea. Interestingly, the low-molecular-weight fraction from CC2 leaves with CHI2 removed also had fungistatic activity against B. cinerea. Not only the introduced chitinase activity but also the endogenous defense reactions activated by overexpression of CHI2 may be involved in the enhanced gray mold disease resistance in CC2.