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1.
植物抗寒机理研究进展   总被引:74,自引:2,他引:72  
本文综合概述了国内外有关植物抗寒机理研究的动态,主要讨论了植物抗寒性与细胞膜系、酶系多态性及抗寒基因表达与调控之间的相关性。此外,亦提出了有关植物抗寒机制研究领域值得深入研讨的问题。  相似文献
2.
交变应力作用下烟草细胞热力学相行为的研究   总被引:28,自引:0,他引:28       下载免费PDF全文
研究了交变应力对烟草愈伤组织细胞的影响, 采用本实验室研制的强声波发生装置来产生交变应力场, 并利用差式扫描量热仪(DSC) 研究了不同强度和频率的交变应力作用后烟草细胞热力学相行为的变化。研究结果表明:交变应力的影响与应力的频率和强度密切相关,一定频率和强度范围内的交变应力能使得植物细胞的相变温度有明显的降低, 而过高频率的应力刺激则会使细胞相变温度升高。细胞热力学相变反映了细胞壁膜的流动性,相变温度变低表明细胞壁膜的流动性增强, 这必然为细胞的生长和分裂提供了便利的条件。 因此, 对于从细胞和分子水平研究交变应力对植物生长、发育的影响及其作用机理是一个很有意义的尝试  相似文献
3.
Aerobic granular sludge: recent advances   总被引:27,自引:1,他引:26  
Aerobic granulation, a novel environmental biotechnological process, was increasingly drawing interest of researchers engaging in work in the area of biological wastewater treatment. Developed about one decade ago, it was exciting research work that explored beyond the limits of aerobic wastewater treatment such as treatment of high strength organic wastewaters, bioremediation of toxic aromatic pollutants including phenol, toluene, pyridine and textile dyes, removal of nitrogen, phosphate, sulphate and nuclear waste and adsorption of heavy metals. Despite this intensive research the mechanisms responsible for aerobic granulation and the strategy to expedite the formation of granular sludge, and effects of different operational and environmental factors have not yet been clearly described. This paper provides an up-to-date review on recent research development in aerobic biogranulation technology and applications in treating toxic industrial and municipal wastewaters. Factors affecting granulation, granule characterization, granulation hypotheses, effects of different operational parameters on aerobic granulation, response of aerobic granules to different environmental conditions, their applications in bioremediations, and possible future trends were delineated. The review attempts to shed light on the fundamental understanding in aerobic granulation by newly employed confocal laser scanning microscopic techniques and microscopic observations of granules.  相似文献
4.
Rosmarinic acid   总被引:23,自引:0,他引:23  
Rosmarinic acid is an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid. It is commonly found in species of the Boraginaceae and the subfamily Nepetoideae of the Lamiaceae. However, it is also found in species of other higher plant families and in some fern and hornwort species. Rosmarinic acid has a number of interesting biological activities, e.g. antiviral, antibacterial, antiinflammatory and antioxidant. The presence of rosmarinic acid in medicinal plants, herbs and spices has beneficial and health promoting effects. In plants, rosmarinic acid is supposed to act as a preformed constitutively accumulated defence compound. The biosynthesis of rosmarinic acid starts with the amino acids L-phenylalanine and L-tyrosine. All eight enzymes involved in the biosynthesis are known and characterised and cDNAs of several of the involved genes have been isolated. Plant cell cultures, e.g. from Coleus blumei or Salvia officinalis, accumulate rosmarinic acid in amounts much higher than in the plant itself (up to 36% of the cell dry weight). For this reason a biotechnological production of rosmarinic acid with plant cell cultures has been proposed.  相似文献
5.
The objectives of this study were the changes of antioxidative key enzyme activities under stress conditions induced by a peroxidizing herbicide using photoheterotrophi-cally grown, suspension-cultured soybean celts ( Glycine max L.). Within two days, 50 to 500 n M oxyfluorfen. a p-nitrodiphenyl ether herbicide, caused up to 100% inhibition of growth, while simultaneously, the chlorophyll was 25% to completely bleached. The major cellular antioxidants ascorbate and glutathione showed different responses. Under stress conditions with more than 250 n M oxyfluorfen, the cellular ascorbate- concentration was halved, whereas dehydroascorbate remained roughly constant. The glutathione content (approximately one-fifth of that of ascorbate in untreated control cells) increased nearly 3-fold in the presence of 250 n M oxyfluorfen. Under this condition, oxidized glutathione was 5 times above the control level. The specific activities of selected enzymes participating in cellular defence, namely ascor-bate peroxidase, glutathione reductase, rnonodehydroascorbate reductase. peroxidase and catalase increased by 40 to 70% with oxyfluorfen concentrations between 50 and 500 n M , while dehydroascorbate reductase showed a significant decrease. Glutathione transferase activity even increased 6-fold under oxyfluorfen stress.  相似文献
6.
7.
Actin and actin-binding proteins in higher plants   总被引:18,自引:0,他引:18  
Summary The actin cytoskeleton is a complex and dynamic structure that participates in diverse cellular events which contribute to plant morphogenesis and development. Plant actins and associated actin-binding proteins are encoded by large, differentially expressed gene families. The complexity of these gene families is thought to have been conserved to maintain a pool of protein isovariants with unique properties, thus providing a mechanistic basis for the observed diversity of plant actin functions. Plants contain actin-binding proteins which regulate the supramolecular organization and function of the actin cytoskeleton, including monomer-binding proteins (profilin), severing and dynamizing proteins (ADF/cofilin), and side-binding proteins (fimbrin, 135-ABP/villin, 115-ABP). Although significant progress in documenting the biochemical activities of many of these classes of proteins has been made, the precise roles of actin-binding proteins in vivo awaits clarification by detailed mutational analyses.Dedicated to Professor Brian E. S. Gunning on the occasion of his 65th birthday  相似文献
8.
水杨酸在紫杉醇生物合成中诱导作用的研究   总被引:18,自引:0,他引:18       下载免费PDF全文
研究了水杨酸对红豆杉细胞培养中紫杉烷合成的影响。在适宜浓度的水杨酸诱导下,紫杉醇(Taxol)的产量提高了近3倍,同时10去乙酰基巴卡亭Ⅲ(10-DAB)与巴卡亭Ⅲ(Baccatin Ⅲ)相应上升。通过对紫杉醇合成代谢途径的动力学分析,初步推断水杨酸的加入提高了10-DAB合成速率。并通过水杨酸和硝酸银的配伍诱导,实现了诱导子之间的协同作用,获得了39 mg/L的紫杉醇含量,比两个诱导子单独作用时的最高含量之和还高出50%。  相似文献
9.
The molecular basis of plant cell wall extension   总被引:17,自引:0,他引:17  
In all terrestrial and aquatic plant species the primary cell wall is a dynamic structure, adjusted to fulfil a diversity of functions. However a universal property is its considerable mechanical and tensile strength, whilst being flexible enough to accommodate turgor and allow for cell elongation. The wall is a composite material consisting of a framework of cellulose microfibrils embedded in a matrix of non-cellulosic polysaccharides, interlaced with structural proteins and pectic polymers. The assembly and modification of these polymers within the growing cell wall has, until recently, been poorly understood. Advances in cytological and genetic techniques have thrown light on these processes and have led to the discovery of a number of wall-modifying enzymes which, either directly or indirectly, play a role in the molecular basis of cell wall expansion.  相似文献
10.
Mechanisms that regulate water channels in the plant plasma membrane (PM) were investigated in Arabidopsis suspension cells. Cell hydraulic conductivity was measured with a cell pressure probe and was reduced 4-fold as compared to control values when calcium was added in the pipette and in bathing solution. To assess the significance of these effects in vitro, PM vesicles were isolated by aqueous two-phase partitioning and their water transport properties were characterized by stopped-flow spectrophotometry. Membrane vesicles isolated in standard conditions exhibited reduced water permeability (P(f)) together with a lack of active water channels. In contrast, when prepared in the presence of chelators of divalent cations, PM vesicles showed a 2.3-fold higher P(f) and active water channels. Furthermore, equilibration of purified PM vesicles with divalent cations reduced their P(f ) and water channel activity down to the basal level of membranes isolated in standard conditions. Ca2+ was the most efficient with a half-inhibition of P(f) at 50-100 microM free Ca2+. Water transport in purified PM vesicles was also reversibly blocked by H+, with a half-inhibition of P(f )at pH 7.2-7.5. Thus, both Ca2+ and H+ contribute to a membrane-delimited switch from active to inactive water channels that may allow coupling of water transport to cell signalling and metabolism.  相似文献
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