A facile transformation of Arabidopsis thaliana using ceramic supported propagation system

Arabidopsis thaliana can be a useful model plant in the field of plant molecular biology because it is a sole dicotyledonous plant whose genome sequence has been completely determined at the present time. To develop functional genomics of A. thaliana, a large number of transgenic plants must be produced. However, transformation of the plants requires wide space and long time. For these reasons, a highly efficient method has been desired to be developed. In order to save space, the transformation system was improved, based on a new technology for plant propagation using ceramic tubes. The new method using ceramic tubes facilitated to prepare plants with a uniform growth level. In addition, the colander procedure after infiltration, which is one of tedious procedures, could be omitted. The new system without soil usage could cut down the cleaning up after experiment.     

Efficient construction of cDNA microarrays utilizing normalized cDNA libraries of Arabidopsis thaliana

We have demonstrated the utility of normalization for efficient cDNA microarray preparation using Arabidopsis as a model. Nonredundant cDNAs including 5722 species were efficiently collected from random 7914 expressed sequence tags (ESTs) in four normalized cDNA libraries. The prepared microarrays were successfully used to monitor gene expression. These methodologies should be applicable to the study of other species in plant biotechnology.     

Preferential binding of SBD from Arabidopsis thaliana SSIII to polysaccharides: Study of amino acid residues involved

SS III (SSIII) has been reported to play a regulatory role in the synthesis of transient starch. SSIII from Arabidopsis thaliana contains 1025 amino acid residues and has an N‐terminal transit peptide for chloroplast localization followed by three in tandem starch‐binding domains (SBDs D1, D2, and D3, residues 22‐591). Its C‐terminal catalytic domain (residues 592–1025) is similar to bacterial glycogen synthase. Binding studies to raw starch and its individual components, AM or AP show that the SBD region binds preferentially to AM, and that the D1 domain is mainly responsible for this selective binding. The D2 domain contains two binding sites which include amino acid residues Y394 (binding site 1) and W366 (binding site 2) acting cooperatively with the D1 domain in the binding process while G335 and W340 have a minor role. In addition, mutations in these residues also affect the kinetic parameters for the polysaccharide substrate of SSIII.     

Growth and persistence of Listeria monocytogenes isolates on the plant model Arabidopsis thaliana

While the majority of human listeriosis cases appear to be linked to consumption of processed ready-to-eat foods (e.g., deli meats), a few listeriosis outbreaks have been linked to consumption of contaminated vegetables. In this study, we assessed four isolates representing the major Listeria monocytogenes lineages for their abilities to attach to and grow on Arabidopsis thaliana, a well-characterized plant model. When plants were dipped for 5min into 3ml of water containing 8.8logCFU of L. monocytogenes and rinsed repeatedly, L. monocytogenes was recovered from the leaves at densities from 1.52 to 2.17logCFU/cm(2). Ten days after exposure, bacterial numbers had increased over initial numbers by 2.60-2.95logCFU/cm(2). Using L. monocytogenes expressing GFP, bacteria were visualized in the intercellular spaces of A. thaliana leaves, suggesting internalization through stomata. These data indicate that L. monocytogenes can rapidly attach to and multiply on plant surfaces and colonize intercellular spaces in A. thaliana leaves where it may be protected from sanitation treatments. When A. thaliana seeds were exposed to L. monocytogenes, between 4.23 and 4.57logCFU/cm(2) were recovered from leaves 7 days post-germination, suggesting that contaminated seeds can produce contaminated plants. Overall, our study demonstrates that prevention of L. monocytogenes contamination of plants throughout growing stages is critical, consistent with recommendations for other produce-transmitted foodborne pathogens.     

Promoter of Arabidopsis thaliana phosphate transporter gene drives root-specific expression of transgene in rice

The PHT1 promoter::GUS fusion gene was constructed and introduced into Arabidopsis and rice by Agrobacterium-mediated transformation. Strong beta-glucuronidase (GUS) activity was detected in roots and showed phosphate starvation induction both in Arabidopsis and rice. In contrast, GUS activity in aerial tissues such as those of the leaf and stem was low. In situ GUS staining of root tissue indicated that PHT1 was expressed in root hairs and the outer layer of the main roots, but not in root tips. The PHT1 promoter has a desirable character for biotechnological transgene expression in monocot rice plants.     

Formate dehydrogenase gene of Arabidopsis thaliana is induced by formaldehyde and not by formic acid

Variability of expression of formate dehydrogenase (FDH) caused by uptake of C-1 compounds was examined by using Arabidopsis thaliana as a model plant. Effects of uptake of several C-1 compounds were evaluated by Northern blot analysis using cDNA of A. thaliana FDH prepared by cloning on the basis of known sequence. As a result, expression of the FDH gene in A. thaliana was not intensely influenced by formic acid, an inherent substrate for FDH, but strongly induced by its reduced form, formaldehyde.     

Phytotoxicity due to the agricultural use of urban wastes. Germination experiments

The inhibitory effect on germination by the organic fraction of different urban wastes was studied in two experiments: on barley (Hordeum vulgare L cv Reinete) seeds in petri dishes and on ryegrass (Lolium perenne L cv Argo) seeds in containers. The urban wastes were mixed with a calcareous soil. Fresh sewage sludge almost totally inhibited germination of barley seeds when used as substrate; fresh municipal solid waste also inhibited germination, although to a lesser degree. Both inhibitory effects were less pronounced when the products had been composted previously. Similar results were obtained when the experiments were carried out with water extracts although overall inhibition was less. Correlation between germination indices and various parameters of the products used showed that the highest indices were obtained when the organic matter of the samples was the most stable (a smaller proportion of labile carbon, carbon extracted with Na₁P₂O⁷, carbon precipitated at pH 2 and water soluble carbon in the materials and extracts). Inhibition was greater when there were greater quantities of NH^?₄, polyphenols and organic acids of low molecular weight. Yields of ryegrass obtained from high doses of urban wastes (180 t ha ^?1) mixed with a calcareous soil were less than those of the control at the first harvest, these yields being influenced negatively by the same factors as above; at the second harvest the yields with most of the products used were higher than those of the control, probably as a result of their maturation in the soil. When the water extracts of the products were added to the soil, no significant differences from the control were noted at the first harvest.     

大豆24kDa油体蛋白与人bFGF融合基因转化拟南芥的研究

为探索大豆油体蛋白与人bFGF（碱性成纤维细胞生长因子）蛋白在植物油体中融合表达的可行性,以大豆总DNA为模板,通过PCR扩增得到大豆油体蛋白基因（Ddoil）及启动子（Ddprm）,构建Ddprm启动的Ddoil基因与植物偏好密码子改造的bFGF基因融合表达载体p1390Ddprm-Ddoil-bFGF,花侵染法转化拟南芥,对T2拟南芥抗性植株基因组进行PCR检测,对种子总蛋白进行SDS-PAGE分析、Western blot检测、ELISA检测及细胞活性测定,为bFGF在其他油料作物的油体系统的表达提供参考。     

Enantioselective Damage of Diclofop Acid Mediated by Oxidative Stress and Acetyl-CoA Carboxylase in Nontarget Plant Arabidopsis thaliana

Diclofop-methyl (DM) is a widely used chiral herbicide, which rapidly hydrolyzes to its major metabolite diclofop acid (DC) after application. With a carbon chiral center, DC not only is an important ingredient of herbicidal activity, but also has a long half-life in soil. Studies so far have only considered the activity of racemic DM in target organisms, and the enantioselective toxicity in nontarget plants of DM and DC has yet to be explored. In this study, the enantioselective phytotoxicity of DC mediated by oxidative stress and the key enzyme ACCase in the fatty acid synthesis system on the model plant Arabidopsis thaliana was investigated. Significant differences between the two enantiomers were observed in phytotoxicity including growth inhibition, oxidative damage and alteration of key genes expression of ACCase, with R-DC showing greater toxicity to Arabidopsis thaliana than S-DC. The results of molecular docking showed that there was a stronger affinity between R-DC and the target enzyme carboxyltransferase domain of ACCase, likely leading to the enantioselective phytotoxicity of DC. This study suggested that chirality of both parent compounds and metabolites should be considered to improve our understanding of the environmental fate and risks of chiral pesticides.     

Systematic transient assays of promoter activities for leaf-specific genes identified by gene-expression profiling with cDNA microarrays in Arabidopsis thaliana

We identified 85 genes highly expressed in leaves using an Arabidopsis cDNA microarray. A vector, pRAB5, was designed to allow cloning and assaying of the promoters. Fifty-one promoters from the selected genes were cloned and then assayed using a microprojectile bombardment and dual luciferase reporter assay system. This system allowed efficient systematic assays of promoter activity.     

Identification of putative gene encoded on ORF16 of the 81 kb contig of Arabidopsis thaliana chromosome III as alpha-mannosidase

We isolated cDNA corresponding to open reading frame (ORF) 16 of the 81 kb contig of Arabidopsis thaliana chromosome III [Quigley., Nucleic Acids Res., 24, 4313-4318 (1996)] and expressed alpha-mannosidase activity in tobacco suspension-cultured cells, which revealed that ORF16 encodes alpha-mannosidase. We also suggested that Arabidopsis harbors three genes encoding alpha-mannosidase by homology search against the database.     

纳米二氧化硅的制备

叙述了纳米二氧化硅的制备研究.试验以无机盐--氯化钠为反应介质,使用不同浓度的硅酸钠和硫酸分别在pH=9,pH=6,和pH=3条件下进行反应,生成水合二氧化硅,经过滤、洗涤,干燥制得纳米二氧化硅.制备的纳米二氧化硅样品进行了堆积密度、比表面积、孔容积和粒度以及TEM的测定.从几种测定的结果可以看出,本试验方法制备的纳米二氧化硅粒径在9 nm～37 nm之间.最佳条件制备的纳米二氧化硅粒径在10 nm左右.     

Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) determination of phase II metabolites of the mycotoxin zearalenone in the model plant Arabidopsis thaliana.

The biotransformation products of zearalenone, a Fusarium mycotoxin, were elucidated using the model plant Arabidopsis thaliana. After treatment of plant seedlings with 50 microM zearalenone, both the liquid media and the plant extracts were analysed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). An array of 17 different metabolites, most prominently glucosides, malonylglucosides, di-hexose- and hexose-pentose disaccharides of zearalenone, and alpha- and beta-zearalenol, were detected in the samples. Time courses for the different zearalenone metabolites were recorded and they give a closer insight into the metabolism kinetics. A scheme proposing the zearalenone metabolism in A. thaliana is given. The aspect of food safety regarding the (potential) occurrence of masked mycotoxins in agricultural commodities is discussed.     

胶体二氧化硅微粒助留助滤体系

简述了胶体二氧化硅微粒助留助滤剂的结构、制备方法及其体系的发展情况，分析了各体系的优缺点和该体系的发展空间。     

茶多酚-壳聚糖纳米共悬液的制备及性质研究

利用离子交联法制备了茶多酚壳-聚糖纳米共悬液。全面研究了影响共悬液中茶多酚-壳聚糖颗粒粒径分布及茶多酚包封率的因素,结果显示:pH值、搅拌速度、反应温度、壳聚糖浓度、茶多酚添加量、三聚磷酸钠与壳聚糖质量比以及超声处理对粒径分布与包封率均有不同程度的影响,进而优化了制备工艺,并对最佳工艺条件下制备的茶多酚-壳聚糖纳米共悬液的性质做了研究。     

Insights into the structural and functional evolution of plant genomes afforded by the nucleotide sequences of chromosomes 2 and 4 of Arabidopsis thaliana

The rapidly accumulating genome sequence data from the plant Arabidopsis thaliana allows more detailed analysis of genome content and organisation than ever before possible in plants. The genome shows a surprisingly high level of genetic redundancy, with as many as 75% of gene products showing significant homology to another protein of A. thaliana. Many duplicated genes occur in arrays of conserved order and indicate that A. thaliana is likely to have had a tetraploid ancestor. Analysis of the divergence of duplicated genome segments leads to the prediction of two major modes of plant genome evolution: macro-scale duplication and rearrangement of chromosomes and micro-scale translocations, duplication and loss of individual genes or small groups of genes.     

改性微粒硅溶胶的结构和形态

用IR谱、29Si-NMR、11B-NMR和27Al-NMR谱及透射电镜对铝改性硅溶胶与硼改性硅溶胶进行了结构形态与特征的分析研究,首次提出了铝改性硅溶胶与硼改性硅溶胶的结构和形态特征.铝改性硅溶胶胶粒中的Al主要是以与[SiO4]四面体相连接的[AlO4]四面体的形式存在.硼改性硅溶胶胶粒中的硼主要以与4个硅原子相连接的[BO4]四面体的形式存在,同时还有与3个硅原子相连接的[BO4]四面体的形式.铝、硼改性硅溶胶带有强负电性,颗粒是无定型的,粒径在3 nm左右,属于微粒粒子.