拟南芥直播水培法

在参考国内外水培拟南芥的经验和方法的基础上,采用简易的水培装置,对拟南芥直播水培方法进行了探索.     

一种简易可行的拟南芥水培新方法

在国内外拟南芥水培方法研究基础上,结合实际情况,设计一套适合于实验室的需要,能就地取材自己制作的水培装置.这套装置主要由两部分组成:播放种子的塑料管和作为支撑物的不锈钢丝网,盛溶液的容器.实验证明两个拟南芥品种在这种水培装置中生长良好,且培养的费用低,易于管理等.由于有钢丝网作支撑,拟南芥能够顺利完成整个生长周期并且结实饱满,种子萌发率高.     

Arabidopsis thaliana WAPL Is Essential for the Prophase Removal of Cohesin during Meiosis

Sister chromatid cohesion, which is mediated by the cohesin complex, is essential for the proper segregation of chromosomes in mitosis and meiosis. The establishment of stable sister chromatid cohesion occurs during DNA replication and involves acetylation of the complex by the acetyltransferase CTF7. In higher eukaryotes, the majority of cohesin complexes are removed from chromosomes during prophase. Studies in fly and human have shown that this process involves the WAPL mediated opening of the cohesin ring at the junction between the SMC3 ATPase domain and the N-terminal domain of cohesin''s α-kleisin subunit. We report here the isolation and detailed characterization of WAPL in Arabidopsis thaliana. We show that Arabidopsis contains two WAPL genes, which share overlapping functions. Plants in which both WAPL genes contain T-DNA insertions show relatively normal growth and development but exhibit a significant reduction in male and female fertility. The removal of cohesin from chromosomes during meiotic prophase is blocked in Atwapl mutants resulting in chromosome bridges, broken chromosomes and uneven chromosome segregation. In contrast, while subtle mitotic alterations are observed in some somatic cells, cohesin complexes appear to be removed normally. Finally, we show that mutations in AtWAPL suppress the lethality associated with inactivation of AtCTF7. Taken together our results demonstrate that WAPL plays a critical role in meiosis and raises the possibility that mechanisms involved in the prophase removal of cohesin may vary between mitosis and meiosis in plants.     

一种改进的诱发拟南芥产生系统抗病性的方法

报告了诱发拟南芥产生系统抗性的改进的方法。通过直接用荧光假单胞菌(Pseudomonas fluores-cent)M18菌悬液浇灌植株根际代替收集菌体与土壤混合的方法、以直接播种替代移苗以及以病原菌喷雾接种法替代蘸叶接种法,在拟南芥(Arabidopsis thali-ana)生态型Columbia中,有效地建立了诱导性系统抗性(induced systemic resistance,ISR)的实验模式。这种改进的方法简化了操作步骤,缩短了试验周期,使大规模筛选ISR突变体成为可能,同时还能避免因移栽引起的各种其他抗性反应的干扰。     

Internet Resources for Gene Expression Analysis in Arabidopsis thaliana

The number of online databases and web-tools for gene expression analysis in Arabidopsis thaliana has increased tremendously during the last years. These resources permit the database-assisted identification of putative cis-regulatory DNA sequences, their binding proteins, and the determination of common cis-regulatory motifs in coregulated genes. DNA binding proteins may be predicted by the type of cis-regulatory motif. Further questions of combinatorial control based on the interaction of DNA binding proteins and the colocalization of cis-regulatory motifs can be addressed. The database-assisted spatial and temporal expression analysis of DNA binding proteins and their target genes may help to further refine experimental approaches. Signal transduction pathways upstream of regulated genes are not yet fully accessible in databases mainly because they need to be manually annotated. This review focuses on the use of the AthaMap and PathoPlant^® databases for gene expression regulation analysis and discusses similar and complementary online databases and web-tools. Online databases are helpful for the development of working hypothesis and for designing subsequent experiments.     

A genetic framework for fruit patterning in Arabidopsis thaliana

In the model plant Arabidopsis thaliana, the establishment of organ polarity leads to the expression of FILAMENTOUS FLOWER (FIL) and YABBY3 (YAB3) on one side of an organ. One important question that has remained unanswered is how does this positional information lead to the correct spatial activation of genes controlling tissue identity? We provide the first functional link between polarity establishment and the regulation of tissue identity by showing that FIL and YAB3 control the non-overlapping expression patterns of FRUITFULL (FUL) and SHATTERPROOF (SHP), genes necessary to form stripes of valve margin tissue that allow the fruit to shatter along two defined borders and disperse the seeds. FIL and YAB3 activate FUL and SHP redundantly with JAGGED (JAG), a gene that also promotes growth in organs, indicating that several pathways converge to regulate these genes. These activities are negatively regulated by REPLUMLESS (RPL), which divides FIL/JAG activity, creating two distinct stripes of valve margin.     

Functional bioinformatics for Arabidopsis thaliana

MOTIVATION: The genome of Arabidopsis thaliana, which has the best understood plant genome, still has approximately one-third of its genes with no functional annotation at all from either MIPS or TAIR. We have applied our Data Mining Prediction (DMP) method to the problem of predicting the functional classes of these protein sequences. This method is based on using a hybrid machine-learning/data-mining method to identify patterns in the bioinformatic data about sequences that are predictive of function. We use data about sequence, predicted secondary structure, predicted structural domain, InterPro patterns, sequence similarity profile and expressions data. RESULTS: We predicted the functional class of a high percentage of the Arabidopsis genes with currently unknown function. These predictions are interpretable and have good test accuracies. We describe in detail seven of the rules produced.     

Functional bioinformatics for Arabidopsis thaliana

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Variations in Sulfhydryl Concentration During Microsporocyte Meiosis in the Anthers of Lilium and Trillium

Anthers of lily and trillium were followed with respect to variations in protein and soluble sulfhydryls during meiosis and mitosis of the sporogenous tissue. In lily, the meiotic and mitotic cycles are each preceded by a rise in soluble —SH; in trillium there is only one rise which precedes meiosis. During division there is a marked drop in soluble —SH and a rise in soluble disulfides. Protein —SH remains approximately constant until diakinesis or metaphase when it falls briefly.     

A puromycin-sensitive aminopeptidase is essential for meiosis in Arabidopsis thaliana

Puromycin-sensitive aminopeptidases (PSAs) participate in a variety of proteolytic events essential for cell growth and viability, and in fertility in a broad range of organisms. We have identified and characterized an Arabidopsis thaliana mutant (mpa1) from a pool of T-DNA tagged lines that lacks PSA activity. This line exhibits reduced fertility, producing shorter siliques (fruits) bearing a lower number of seeds compared with wild-type plants. Cytogenetic characterization of meiosis in the mutant line reveals that both male and female meiosis are defective. In mpa1, early prophase I appears normal, but after pachytene most of the homologous chromosomes are desynaptic, thus, by metaphase I a high level of univalence is observed subsequently leading to abnormal chromosome segregation. Wild-type plants treated with specific inhibitors of PSA show a very similar desynaptic phenotype to that of the mutant line. A fluorescent PSA-specific bioprobe, DAMPAQ-22, reveals that the protein is maximally expressed in wild-type meiocytes during prophase I and is absent in mpa1. Immunolocalization of meiotic proteins showed that the meiotic recombination pathway is disrupted in mpa1. Chromosome pairing and early recombination appears normal, but progression to later stages of recombination and complete synapsis of homologous chromosomes are blocked.     

A method for measuring whole plant photosynthesis in Arabidopsis thaliana

Measurement of photosynthesis of intact leaves of Arabidopsis thaliana has been prohibitive due to the small leaf size and prostrate growth habit. Because of the widespread use of Arabidopsis for plant science research it is important to have a procedure for accurate, nondestructive measurement of its photosynthesis. We developed and tested a method for analysis of photosynthesis in whole plants of Arabidopsis. Net carbon assimilation and stomatal conductance were measured with an open gas exchange system and photosynthetic oxygen evolution was determined from chlorophyll fluorescence parameters. Individual plants were grown in 50 cubic centimeter tubes that were attached with an air tight seal to an enclosed gas exchange chamber for measurement of carbon dioxide and water exchange by the whole plant. Chlorophyll fluorescence from intact leaves was simultaneously measured with a pulse modulated fluorometer. Photosynthetic CO₂ assimilation and stomatal conductance rates were calculated with established gas exchange procedures and O₂ evolution was determined from chlorophyll fluorescence measurement of Photosystem II yield. Carbon assimilation and oxygen evolution in response to light intensity and ambient CO₂ concentration was measured and is presented here to demonstrate the potential use of this method for investigation of photosynthesis of Arabidopsis plants in controlled environment conditions.     

A novel method for growing Arabidopsis thaliana plants hydroponically

In this report we describe the development of a simple system for growing individual Arabidopsis plants hydroponically under environmental conditions which are simple to maintain while maximizing growth and development. The system consists of a Life Raft Float Unit with a 14–20 mm sponge inserted into its center; this unit is placed into a Magenta GA7 vessel containing Arabidopsis nutrient solution. Plants grown in this experimental system do not require aeration, 125 μmol m⁻² s⁻¹ supports vigorous plant growth, 1/4 to 1/8 strength Arabidopsis nutrient solution promotes maximal growth while higher or lower levels have adverse effects and temperatures between 18 and 24°C were found to be optimal. Plants grown under these conditions exhibit physiological factors such as time to flowering and overall appearance similar to those grown in potting media. The low maintenance method described in this paper provides an alternative to existing hydroponic methods used to grow Arabidopsis . Adaptation of this system for growing large numbers of plants in 1 container is also discussed.     

A Simple Hydroponic Culture Method for the Development of a Highly Viable Root System in Arabidopsis thaliana

In the studies of nutritional absorption and metal toxicity in the root, it is important to grow plants without technical damage. We established a simple hydroponic culture system for Arabidopsis thaliana to obtain a healthy plant having a well-developed root system with many lateral roots. The phytotoxic effects of Cr, Cu, and Al ions were examined by FDA-PI staining using this culture system. The pattern of root inhibition varied with the ion, suggesting the usefulness of this culture system.     

拟南芥PHD-finger蛋白家族的全基因组分析

PHD—finger蛋白是一类广泛存在于真核生物中,在基因转录和染色质状态调控方面有重要作用的锌指蛋白。目前在动物中对PHD—finger蛋白的结构和功能方面的研究较为广泛和深入,而在植物中仅有少数PHD—finger蛋白的功能被阐明。通过SMART和Pfam等数据库分析,我们发现拟南芥中共有70个PHD-finger蛋白,其中大部分PHD—tinger蛋白的功能未知。本文通过生物信息学分析获得拟南芥PHD-tinger家族较为全面的信息,包括基因结构、染色体定位、基因表达、蛋白结构域、系统进化关系等,为深入研究PHD-finger家族蛋白的结构与功能提供了参考。     

A Micromechanics Model for Turgor Pressure of Arabidopsis thaliana Protoplast

Understanding the key role of turgor pressure in plant growth and development is important for recognizing the mechanical behavior of plant cell wall material deposition. In this study, we developed a micromechanics model to demonstrate how uniaxial strain influences turgor pressure of isolated Arabidopsis thaliana protoplasts, and their deformation and morphogenesis. In this model, the protoplast is treated as an elastic inclusion in a surrounding agarose gel, allowing the turgor pressure in response to the 20 % uniaxial strain exerted on the protoplast–agarose gel composite material system. Based on the Eshelby method and the Mori–Tanaka’s theory (Eshelby in Proc R Soc Lond A 241(1226):376–396, 1957; Mori and Tanaka in Acta Metall 21(5):571–574, 1973), turgor pressure can be taken into account as a uniform strain acting on protoplasts. By using this model, the relationship between the plant cell morphology changes, and their effective properties are derived with a theoretical basis.