腔蚓属一新种(后孔寡毛目:巨蚓科)

本文报道采自我国甘肃省的腔蚓Metaphire Sims et Easton属一新种。模式标本保存于兰州医学院生物学教研室。 绿腔蚓,新种Metaphire viridis sp. nov. 外部特点:体长192—230mm,体宽9.5—10mm,体节数124—128(模式:192mm长,10mm宽,124节)。口前叶为1/2上叶式。背孔自12/13节间出现。生活时背面深绿色,腹面淡绿色。环带占xiv—xvi节,长9—10mm,戒指状,无刚毛,无刚毛窝,有背孔痕迹。     

Leaf traits associated with flavonol glycoside genes in soybean

In the soybean (Glycine max (L.) Merr.), the gene combination Fg1 Fg3 is responsible for the glycosylation in the biosynthesis of kaempferol triglucoside (K9) in leaves. The presence of K9 is associated with reduction in chlorophyll content, specific leaf mass, photosynthetic rate and stomatal frequency. Blocking the action of Fg1 Fg3 with the magenta flower gene wm prevents formation of K9 and restores leaf traits to normal. A direct effect of K9 on leaf development is postulated.     

Measurement of bacterial random motility and chemotaxis coefficients: I. Stopped-flow diffusion chamber assay

Bacterial chemotaxis, the directed movement of a cell population in response to a chemical gradient, plays a critical role in the distribution and dynamic interaction of bacterial populations in nonmixed systems. Therefore, in order to make reliable predictions about the migratory behavior of bacteria within the environment, a quantitative characterization of the chemotactic response in terms of intrinsic cell properties is needed.The design of the stopped-flow diffusion chamber (SFDC) provides a well-characterized chemical gradient and reliable method for measuring bacterial migration behavior. During flow through the chamber, a step change in chemical concentration is imposed on a uniform suspension of bacteria. Once flow is stopped, diffusion causes a transient chemical gradient to develop, and bacteria respond by forming a band of high cell density which travels toward higher concentrations of the attractant. Changes in bacterial spatial distributions observed through light scattering are recorded on photomicrographs during a 10-min period. Computer-aided image analysis converts absorbance of the photographic negatives to a digital representation of bacterial density profiles. A mathematical model (part II) is used to quantitatively characterize these observations in terms of intrinsic cell parameters: a chemotactic sensitivity coefficient, mu(0), from the aggregate cell density accumulated in the band and a random motility coefficient, mu, from population dispersion in the absence of a chemical gradient.Using the SFDC assay and an individual-cell-based mathematical model, we successfully determined values for both of these population parameters for Escherichia coli K12 responding to fucose. The values obtained were mu = 1.1 +/- 0. 4 x 10(-5) cm(2)/s and chi(o) = 8 +/- 3 +/- 10(-5) cm(2)/s. We have demonstrated a method capable of determining these parameter values from the now validated mathematical model which will be useful for predicting bacterial migration in application systems.     

An improved microwave assisted one-pot synthesis, and biological investigations of some novel aryldiazenyl chromeno fused pyrrolidines

An improved microwave assisted one-pot method for the synthesis of twelve new aryldiazenylchromeno [4,3-b] pyrrolidines via intramolecular azomethine ylide cycloaddition route is described. The method is efficient and advantageous over conventional and solvent-free thermal methods. The stereochemistry of the compounds was confirmed on the basis of various NMR experiments, and finally by single crystal X-ray diffraction data. N-Methyl or ethyl pyrrolidine based heterocycles gave good biological activities.     

贝莱斯芽孢杆菌RJW-5-5的分离鉴定及细菌素、抗菌肽基因簇挖掘

[背景]化学防治污染日益严重,作物抗性、农药残留、病害再生现象越来越普遍,因此筛选新型生防菌株及研究其抗菌物质已成为热点.[目的]筛选出一株对禾旋孢腔菌等植物病原菌具有生防功能的贝莱斯芽孢杆菌,挖掘其调控合成细菌素、抗菌肽(RiPPs)的基因簇.[方法]通过分离筛选、对峙培养等方法筛选出菌株,通过全细胞脂肪酸和Biol...     

Sequence and pH effects of LNA-containing triple helix-forming oligonucleotides: physical chemistry, biochemistry, and modeling studies

Triple helix-forming oligonucleotides (TFOs) have been demonstrated to be capable of interfering with gene expression and modifying genomic DNA in a sequence-specific manner. Partial incorporation of 2'-O,4'-C-methylene linked locked nucleic acid (LNA) residues in TFOs has been shown to enhance significantly triple helix formation, whereas the full-length LNA TFO failed to form a stable triplex. This work is aimed at understanding the triple helix-forming properties of LNA-containing TFOs and at optimally designing their sequences. Both DNA thermal melting, gel retardation, and restriction enzyme experiments as well as modeling studies by molecular mechanics were carried out to investigate the base composition/sequence and pH-dependence effects of LNA-containing TFOs, as well as their structural features underlying triple helix formation. Alternating LNA substitution every 2-3 nucleotides in TFOs is mandatory, whereas the use of thymine LNA residues should be favored under neutral pH conditions. A rule for designing optimal LNA-containing TFOs is proposed. In addition, alternative LNA and 2'-O-methyl residues in TFOs do not significantly improve triple helix formation.     

Isolation of a fluffy mutant of Aspergillus niger from chemostat culture and its potential use as a morphologically stable host for protein production

Chemostat cultivation of Aspergillus niger and other filamentous fungi is often hindered by the spontaneous appearance of morphologic mutants. Using the Variomixing bioreactor and applying different chemostat conditions we tried to optimize morphologic stability in both ammonium- and glucose-limited cultures. In most cultivations mutants with fluffy (aconidial) morphology became dominant. From an ammonium-limited culture, a fluffy mutant was isolated and genetically characterized using the parasexual cycle. The mutant contained a single morphological mutation, causing an increased colony radial growth rate. The fluffy mutant was subjected to transformation and finally conidiospores from a forced heterokaryon were shown to be a proper inoculum for fluffy strain cultivation.     

旱地农田不同耕作系统的能量/碳平衡

摘要：加强农田土壤保持耕作管理,科学认识和调控农田耕作系统能流碳流,提高农业生态系统固碳减排能力,对于减缓农业对全球温室效应的贡献具有重要意义。本研究以北方半湿润偏旱区山西寿阳旱作春玉米土壤保持耕作试验研究为基础,利用田间定位观测数据、辅助能投入参数,土壤呼吸田间原位测定,以及农业生态系统能量/碳平衡分析及碳循环过程模拟方法,综合分析和比较不同耕作（CT传统、RT少耕和NT免耕）系统能量/碳平衡及能-碳关联影响。与CT比较,采用RT和NT措施下工业能耗CO2-C损失降低约4%—12%（相当11—35 kg CO2-C?hm-2?a-1）。在RT和NT系统下耗能系数可降低约6%—10%,能量生产效率可提高约7%—12%。2006—2007年由田间原位测定土壤呼吸CO2-C释放通量估算,在玉米休闲期（尤其是秋耕处理后）,NT条件下土壤呼吸速率一般为最低（NT NT（2005380）>CT（1987375）。不同耕作下的玉米籽粒产量与生育期土壤呼吸通量趋势基本吻合,如2006-2007年玉米产量（kg?hm-2?a-1）平均为,RT（5614268）>NT（5533564）>CT（5487278）。玉米籽粒产量与生育期土壤呼吸通量之间呈密切相关（R2=0.88）。本研究结果得出,RT和NT对农田耕作系统的影响呈碳汇效应,且一般为NT >RT;而CT处理表现为碳源。RT和NT通过增加土壤碳投入是维持和提高土壤有机碳的有效途径。     

ACC deaminase from plant growth-promoting bacteria affects crown gall development

In addition to the well-known roles of indoleacetic acid and cytokinin in crown gall formation, the plant hormone ethylene also plays an important role in this process. Many plant growth-promoting bacteria (PGPB) encode the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which can degrade ACC, the immediate precursor of ethylene in plants, to alpha-ketobutyrate and ammonia and thereby lower plant ethylene levels. To study the effect of ACC deaminase on crown gall development, an ACC deaminase gene from the PGPB Pseudomonas putida UW4 was introduced into Agrobacterium tumefaciens C58, so that the effect of ACC deaminase activity on tumour formation in tomato and castor bean plants could be assessed. Plants were also coinoculated with A. tumefaciens C58 and P. putida UW4 or P. putida UW4-acdS- (an ACC deaminase minus mutant strain). In both types of experiments, it was observed that the presence of ACC deaminase generally inhibited tumour development on both tomato and castor bean plants.