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关键词： molecular chemistry   structural biology   multipeak modeling   Gaussian method   Lorentzian method   protein secondary structure   amide 1   synchrotron light   Fourier transform infrared microspectroscopy   FT-IR microspectroscopy   plant seed tissues  

摘要： The objective of this study was to compare Gaussian and Lorentzian multicomponent peak modeling methods in quantification of protein secondary structures of various plant seed and feed tissues within intact tissue at a cellular and subcellular level using the advanced synchrotron light sourced Fourier transform infrared (FT-IR) microspectroscopy (S-FTIR). This experiment was performed at the beamline U10B at the National Synchrotron Light Source (NSLS) in Brookhaven National Laboratory (BNL), U.S. Dept of Energy (NSLS-BNL, NY). The results show that in the comparison of the Gaussian and Lorentzian multi-peak modeling methods, the Gaussian method is more accurate for fitting multi-peak curves of protein secondary structures than the Lorentzian method, with higher modeling R-2 values (0.92 versus 0.89, P < 0.05). There were no large differences (P > 0.05) in the quantification of the relative percentage of alpha-helices, beta-sheets, and others in protein secondary structures of the plant seed tissues, with averages of 30.2%, 40.4%, and 29.4%, respectively. However, there are significant differences (P < 0.05) in the quantification of the ratios of beta-sheet to alpha-helix (1.42 versus 1.60;SEM = 0.058) in protein secondary structures of the plant seed tissues. With synchrotron FT-IR microspectroscopy, the ultrastructural-chemical makeup and nutritive characteristics could be revealed at a high spatial resolution. Synchrotron-based FT-IR microspectroscopy revealed that the secondary structure of protein differed between the plant seed tissues in terms of relative percentage and ratio of protein secondary structures (alpha-helix and beta-sheet) within cellular dimensions. The results also show that the flaxseed tissues contained higher (P < 0.05) percentage of alpha-helix (38.6 versus 24.0%) and beta-sheet (45.3 versus 36.9%), lower (P < 0.05) percentage of other secondary structures (16.1% versus 39.0%), and higher (P < 0.05) ratios of alpha-helix to beta-sheet (0.90

关键词： Australia   deserts   environmental variability   seed banks   species coexistence   storage effect  

摘要： We used a combination of field studies and laboratory experiments to characterize key ecological aspects of the seed biology and soil seed bank dynamics of annual plant communities in chenopod shrublands of South Australia. A sequential study of the soil seed bank demonstrated seasonal and between-year variability in numbers and composition of the soil seed bank. Soil samples incubated under different temperature and watering regimes produced different communities, indicating that species respond differentially to various environmental combinations. Emergence was extremely low at low water availability and at high temperatures, even in trays with ample water. A high percentage of seeds of four out of five species buried in the field remained viable for two years, while the fifth, Carrichtera annua, showed a sharp decline in seed viability, reaching nearly zero survivorship. Our results indicate that, in this system, annual plant communities result from germination of a fraction of seeds present in the soil seed bank, when autumn or winter rainfalls occur. Because different species have different responses to various combinations of environmental conditions, the community composition varies from year to year. This variability is likely to be a component of coexistence through the storage effect.

关键词： biofumigation   isothiocyanates   glucosinolates   soil   brassicas  

摘要： Four pure isothiocyanates (methyl, 2-propenyl, benzyl and 2-phenylethyl isothiocyanate), hydrolysing tissue of two brassicas rich in either 2-propenyl or 2-phenylethyl isothiocyanate, and the methyl isothiocyanate-generating pesticide metam-sodium were tested in vapour exposure tests for biological activity against a model soil insect both in vitro and in the presence of three contrasting soils and under four temperatures from 5 to 20 degrees C. The purpose was to develop an understanding of the factors controlling isothiocyanate release and maintenance in soil in order to identify advantageous attributes to seek in utilising brassicas for isothiocyanate-based biofumigation. Methyl isothiocyanate, structurally the simplest and the most volatile, was the most biologically active isothiocyanate under all conditions. It was less affected by the presence of soil and by lower temperature than the longer-chain aliphatic 2-propenyl isothiocyanate. The activity of the less volatile aromatic isothiocyanates was reduced much more by soil, with a decline up to many thousand-fold in the presence of soil with high organic matter content at lower temperature. Metam-sodium closely reflected the methyl isothiocyanate results. The results indicate that brassicas rich in aliphatic isothiocyanates are more likely to have the potential to exert stronger isothiocyanate-based biofumigation effects than those similarly rich in aromatic isothiocyanates. (c) 2005 Society of Chemical Industry.

关键词： 植物性细胞   生殖系统   受精细胞   胚胎   实验生物学  

摘要： 我们从事植物生殖的实验研究已有近30年历史.20世纪80年代中后期,我们认识到实验胚胎学的发展趋势是由器官、组织操作向细胞、原生质体操作的水平提升,同时加强研究的多学科性与综合性,从而提出了植物实验生殖生物学与生殖细胞工程的研究思路.

关键词： 《珍稀濒危植物保护生物学》   中国   书评   植物保护  

摘要： 有关中国西南部珍稀濒危植物保护生物学的研究已经开展了一些工作，但是有关资料非常零碎，十分缺乏详尽的第一手野外调查资料，如有关珍稀濒危植物的种群特征、生物学特性、繁殖条件等知识特别欠缺；同时也没有先进的资源共享途径，珍稀濒危植物多样性的信息系统工作仍是空白，更谈不上自动鉴别系统，这种状况与我国西部大开发的急需极不适应。为了不断加强中国学术界内以及与国际间的联系，为全球提供系统的有关中国西南部这一生物多样性保护关键地区的珍稀濒危植物的信息，为中国政府向公众普及生物多样性保护知识提供快捷的信息共享手段和鉴别方法，为决策部门执行中国生物多样性保护行动计划提供全方位的基础数据，具有十分重大的理论价值和实践意义。

关键词： antisense oligodeoxynucleotide inhibition   barley   sugar signalling   starch synthesis   SUSIBA  

摘要： Sugar signalling cascades are important components of regulatory networks in cells. Compared with the situation in bacteria, yeast and animals, participants of the sugar signalling pathways in plants are poorly understood. Several genes involved in starch synthesis are known to be sugar inducible, although the signal transduction pathways remain undisclosed. We reported recently the isolation of SUSIBA2, a transcription factor involved in sugar-mediated regulation of starch synthesis. Here, we used antisense oligodeoxynucleotide (ODN) inhibition, a powerful approach in medical sciences, to block the effects of SUSIBA2 in sugar-treated barley leaves. The uptake and intracellular trafficking of an 18-mer susiba2 antisense ODN in leaves were followed by confocal microscopy. Administration of the antisense ODN to the leaves impeded susiba2 expression by RNase H activation. This dramatically diminished the ectopic expression of the iso1 and sbeIIb genes and resulted in altered starch synthesis. This study illustrates the successful exploitation of the antisense ODN technology in plant biology, e.g. as a rapid antecedent to time-consuming transgenic studies, and identifies SUSIBA2 as a transcriptional activator in plant sugar signalling. Based on our findings, we propose a model for sugar-signalling control of starch synthesis.

关键词： Temperature   Signal Transduction   Plants   Molecular Biology   Lymphotoxin  

摘要： Plants growing in temperate regions are able to survive freezing temperatures from -5 degrees to -30 degrees C, depending on the species, through a process known as cold acclimation. In the last decade much work has been done on the molecular mechanisms of low temperature (LT) signal transduction and cold acclimation. Mutant studies and microarray analyses have revealed C-Repeat binding factor (CBF) -dependent and -independent signaling pathways in plants. Experimental evidence suggests the existence of 'potential LT sensors' but as yet there is no direct proof. A number of signal transducers such as various kinases/phosphatases have been demonstrated but the signal transduction pathways have not been elucidated. An understanding of the molecular basis of the signaling process, however, is of potential practical application. Designing new strategies to improve cold tolerance in crop varieties could increase the plant productivity and also expand the area under cultivation.

关键词： PLANT lipids   NONFICTION  

摘要： Reviews the book 'Plant Lipids: Biology, Utilisation and Manipulation,' edited by Denis J. Murphy.

关键词： 植物多酚   功能活性   生物学活性   结构   次生代谢物   多酚类物质   植物体内   多元酚   自然界  

摘要： 植物多酚是一类广泛存在于植物体内的次生代谢物,具有多元酚结构,在自然界的储量非常丰富。本文就几种比较常见的植物多酚类物质的组成、性质及其功能作了较为详尽的介绍。

关键词： mannose-binding lectin   collectins   innate immunity   polymorphism   infection  

摘要： The innate host defence molecule mannose-binding lectin (MBL) has attracted great interest as a potential candidate for passive immunotherapy to prevent infection. MBL is a multimeric lectin that recognizes a wide array of pathogens independently of specific antibody, and initiates the lectin pathway of complement activation. The basic structural unit is a triple helix of MBL peptides, which aggregate into complement-fixing higher-order structures (tetramers, pentamers and hexamers). The gene encoding MBL, MBL2, contains several common polymorphisms that influence transcription and assembly of the molecule into multimers. MBL2 coding alleles associated with low blood levels are present in up to 40% of Caucasoids, with up to 8% having genotypes associated with profound reduction in circulating MBL levels. Low-producing MBL2 variants and low MBL levels are associated with increased susceptibility to and severity of a variety of infective illnesses, particularly when immunity is already compromised - for example, in infants and young children, patients with cystic fibrosis, and after chemotherapy and transplantation. These observations suggest that administration of recombinant or purified MBL may be of benefit in clinical settings where MBL deficiency is associated with a high burden of infection. This review provides a background to MBL biology and disease associations, and identifies the exciting therapeutic possibilities of MBL replacement.