Isolation of Mesophyll Cells from Mulberry Leaves for Photosynthetic Studies

A procedure was developed for isolating mesophyll cells frommulberry leaves that have consistently high photosynthetic activity.To obtain photosynthetically active cells from some plants,their petioles, immersed in water, had to be kept in the darkfor 3–4 days prior to cell isolation. (Received May 6, 1983; Accepted August 15, 1983)     

Surface Ultrastructural Studies on Ingress and Establishment of Pseudomonas syringae pv. mori on Mulberry Leaves

P. syringae pv. mori multiplied on leaf surface and colonized particularly on the cystoliths and in the grooves of veins. The masses of bacteria were associated with necrotic spots, which appeared 9 days after inoculation. The studies also revealed that the bacterium invaded leaf tissues through cystoliths. However, it did not enter through stomata and trichomes which had commonly been observed in most of the plant pathogenic bacteria.     

Calcium Deposition in Idioblasts of Mulberry Leaves

Large, rounded idioblasts were observed in adaxial leaves ofmulberry plants; they were clearly distinguishable from epidermal,trichome and parenchyma cells. The size and density of idioblastsvaried according to leaf age. Cytological features of idioblastswere as follows: the outermost region (‘cap’) ofidioblasts was situated on the adaxial surface as a dome-likeprotrusion; a cylindrical protuberance extended from the capregion to the inner part of the idioblast; in idioblasts frommature leaves a crystal mass was suspended from the lower tipof the cylindrical protuberance. Elemental analysis of idioblastsdemonstrated that silicon (Si) was localized in both the capregion and the cylindrical protuberance but calcium (Ca) waspresent in the large crystal, indicating site-specific cellularlocalization of Ca and Si within an idioblast. Histochemicalassays showed that a distinct Ca crystal filled the vacuolesof idioblasts in mature leaves, while immature leaves had manyidioblasts without Ca deposition. The increase in the Ca contentof leaves was directly proportional to the increase in leafage and appeared to be closely related to the Ca sink capacityof the developing idioblast vacuoles. The maximum sink capacitywas quantified to be approximately 40 ng per idioblast whenmulberry plants were grown hydroponically with excess Ca.Copyright1999 Annals of Botany Company Morus alba, idioblast, Ca deposition, Ca sink capacity, silicon, X-ray microanalysis, histochemistry, scanning electron microscopy.     

Comparative Studies on Mn,Cr and Mo Contained Reconstituent Solutions and Proteins Reconstituted with Partially Metallocluster-deficient MoFe Protein

By treating the reduced MoFe protein from Azotobacter vinelandii with o-phenanthroline and O2, an inactive protein partially deficient in both FeMoco and P-cluster could be obtained. The inactive protein could be reactivated by the reconsfituent solutions of different colours which were prepared from mixture in different proportions of ferric homocitrate, Na2S and dithiothreitol (DTT) with K2CrO4, KMnO4 and Na2MoO4, respectively, the inactive protein could be somewhat reactivated by DTF but not by the other compounds or their mixtures which were deficient in one or two of the above compounds. 99Mo was found in the reconstituted protein of the inactive MoFe protein with a reconstituent solution containing 99Mo. Its measurement of differential perturbed angular correlation indicated that 41% of 99Mo in the reconstituted protein were in a state similar to that of 99Mo in 99MoFe protein from K. pneumoniae. The results showed that the reactivation of the inactive MoFe rotein was mainly based on the restoration of its metallocluster content. It seemed to be reasonable to postulate that Mn- or Cr-containing nitrogenase could be obtained likewise by the reconstitution of the inactive protein with the Mn- or Cr-containing reconstituent solution.     

BAR结构域蛋白质的功能

近期对果蝇双载蛋白(amphiphysin)BAR结构域晶体结构的报道,使得BAR结构域研究成为热点。虽然在序列水平上保守性较低,但双载蛋白的BAR结构域与Arfaptin 2的GTP酶结合结构域在结构上极为相似。通过对两种蛋白质的BAR结构域同源序列进行检索分析,发现了大量含BAR结构域相关蛋白质。研究发现,BAR结构域蛋白质多数都参与细胞内物质转运及胞吞作用;BAR结构域不仅可以通过其二聚化基元感知和诱导膜的弯曲,而且某些蛋白质的BAR结构域还具有与小GTP酶结合的功能。     

桑叶水提浸膏的抑菌作用研究

研究桑叶水提浸膏对五种食品常见污染菌的抑菌作用。通过滤纸片扩散法测定其相对抑菌活性。结果表明,桑叶水提浸膏对金黄色葡萄球菌有较强的抑制作用,对大肠杆菌作用次之,对枯草芽孢杆菌、荧光假单孢杆菌、巨大芽孢杆菌抑菌效果较差。桑叶水提浸膏对金黄色葡萄球菌的最小抑菌浓度是5%,抑菌作用受pH和温度的影响较大,在酸性条件下抑菌效果较好,低于60℃处理样品对抑菌效果影响不大,但高于80℃处理,样品抑菌活性明显降低。     

Synthesis of Stress Proteins in Tobacco Leaves

Pathogenesis-related proteins (PR proteins), which are knownto be induced in tobacco leaves in response to infection withtobacco mosaic virus (TMV), were isolated by a simple procedureinvolving ammonium sulfate fractionation and preparative gelelectrophoresis. A rabbit antibody to one of the purified PRproteins, designated as PR1a, also reacted with two other PRproteins, designated as PR1b and PR1c in double immunodiffusiontests. Quantitative analysis of these proteins using rocketimmunoelectrophoresis with the antibody showed that they wereinduced not only by infection with TMV but also by mechanicalinjury and osmotic stress at 20?C, although not at 30?C. Basedon these findings, we propose that these proteins be called"stress proteins" rather than "pathogenesis-related proteins." (Received October 23, 1984; Accepted January 18, 1985)     

桑叶挥发油的成分分析

鲜桑叶中的主要化学成分为水分、蛋白质、总糖、脂肪和灰分,其质量分数分别为76.32％、4.75％、16.94％、1.2％和1.05％。桑叶挥发油的回收率约为0.1％(干基)。利用GC/MS对鲜桑叶的挥发油进行了分离鉴定,共检出85个组分,确定了47个化学组分的结构。挥发油中含有大量不饱和的醇和酸,多种脂肪酸,烷烃和芳香族,甾醇类,二萜烯类,杂环类化合物。其中含量最高的是十六碳烯醇(MW296);其次是三甲基环己烯醇(Mw192)和庚烯醇(MW204)等。     

The Fate of Chloroplast Proteins during Photooxidation in Carotenoid-Deficient Maize Leaves

Maize seedlings, treated with the herbicide norflurazon to produce a deficiency in carotenoid pigments, were grown in low-fluence-rate light. Under these conditions, which induced chlorophyll biosynthesis while minimizing photooxidation, carotenoid-deficient seedlings showed identical patterns of chloroplast protein accumulation compared with normal seedlings. Carotenoid pigments thus play no direct role in regulating the accumulation of chloroplast proteins. When shifted to high-fluence-rate light, chlorophyll was rapidly photooxidized in carotenoid-deficient seedlings. Chloroplast proteins showed varying degrees of sensitivity to photooxidation. The P-700 apoprotein of photosystem I was rapidly degraded. Most stromal and thylakoid proteins either decreased progressively in photooxidative conditions or appeared to be unaffected. The relative quantity of the light-harvesting chlorophyll a/b-binding protein of photosystem II increased significantly in the first few hours of high-fluence-rate light. It then appeared to be only minimally affected 18 hours after complete photooxidation of chlorophyll.     

昆虫抗冻蛋白的研究

抗冻蛋白是具有热滞活性,能结合并抑制冰晶生长和抑制冰的重结晶的一类蛋白质。近几年来,昆虫抗冻蛋白的研究取得了较快的发展,本文通过分析昆虫抗冻蛋白的结构特点、抗冻活性、作用机制,并讨论了抗冻蛋白在食品工业、医学、基因工程方面的应用。结果表明,昆虫抗冻蛋白虽然结构呈多样性,但有很多关键的残基具有保守性,对维持抗冻蛋白结构和功能的完整性发挥着重要的作用;抗冻蛋白是由多基因家簇编码的。其作用机制主要是吸附一抑制机制,抗冻蛋白依靠氢键吸附到冰晶格,抑制冰晶生长;昆虫抗冻蛋白的应用具有很广阔的前景。     

Studies on Egg White Proteins

Four components of ovomucoid were digested exhaustively and four kinds of glycopeptide corresponding to the four components were separated by gel filtration. Each glycopeptide was shown to be homogenious by paper chromatography and paper electrophoresis. Molar ratios of carbohydrate components of these glycopeptides varied to some extent but the amino acid compositions of these glycopeptides were essentially identical with each other with the exception of alanine. Aspartic acid and threonine were predominant amino acids in the all glycopeptides. It is most likely that the modes of linkages between polysaccharide and protein in individual ovomucoid I, II, III and IV are essentially the same, and that the carbohydrate moiety is linked to the protein via asparaginyl residue or the hydroxyl group of threonine, although the possibility of the linkages to glutamine and serine can not be excluded.     

果蔗SoSGT1与Gibberella fujikuroi侵染下果蔗叶片蛋白的互作研究

为了解果蔗(Saccharum officenarum L.)在防御Gibberella fujikuroi 过程中与SoSGT1 互作的蛋白,利用GST 蛋白标签载体pGEX-6p-1 与果蔗SoSgt1 基因构建pGEX-6p-1-sgt1 表达载体,诱导表达GST-SoSGT1 融合蛋白,并通过GST pull down 技术捕捉到7 个与SoSGT1 互作蛋白.这些蛋白的功能主要归类为信号转导、抗逆与能量代谢相关蛋白,其中一些蛋白可能与果蔗SoSGT1 直接互作,如HSP90 与RAR1 蛋白,另外一些蛋白与果蔗SoSGT1 可能产生次级互作.在G. fujikuroi 侵染果蔗‘福农’叶片时,HSP70、14-3-3 蛋白、2-半胱氨酸-过氧化物酶与吡哆醇生物合成蛋白的编码基因呈上调表达,初步说明这些蛋白可能与SoSGT1 蛋白互作共同参与了果蔗防御梢腐病病原G. fujikuroi的病理过程.     

Sterols of Mulberry Leaves and Small Leaf Curl Disease

Free and bound sterols of leaves of five mulberry cultivars differing in their susceptibility to small leaf curl disease have been studied. The total content of sterols in all samples is similar and is not correlated with the resistance of the cultivars. The qualitative composition of particular sterols is also identical. They are represented by cholesterol, campesterol, stigmasterol, sitosterol, and two 4α-methylsterols. The leaves of the most sensitive cultivar are characterized by high cholesterol content. The ratio sitosterol : stigmasterol decreased in proportion to the resistance level of a cultivar.__________Translated from Prikladnaya Biokhimiya i Mikrobiologiya, Vol. 41, No. 4, 2005, pp. 460–462.Original Russian Text Copyright © 2005 by Zambakhidze, Sulaberidze, Mzhavanadze, Tsiklauri.