Evolution of epiphytes in Davalliaceae and related ferns

The evolution of epiphytes in Davalliaceae was investigated by field observations and molecular phylogenetic analyses. Field studies revealed that in Davalliaceae and related ferns, epiphytes in a broad sense are classified into climber, secondary hemi-epiphyte, and obligate epiphyte, based on combinations of the places (ground vs. tree) of inferred spore germination and sporophyte growth. Some species of Davalliaceae have multiple life forms, i.e. secondary hemi-epiphyte and obligate epiphyte, whereas others are obligate epiphytes. Phylogenetic trees obtained from rbcL and accD gene sequences supported that secondary hemi-epiphytic Oleandra is sister to the epiphytic Davalliaceae and polygrammoid ferns. Analyses of life form evolution based on the phylogenetic relationships suggested that obligate epiphytes of the Davalliaceae and polygrammoid ferns evolved from secondary hemi-epiphytes, or less likely from climbers. We hypothesized a scenario for the evolution of life forms in Davalliaceae and related groups that involves successive changes in rhizome habit, root function, and germination place. Rhizome dorsiventrality and scale morphology, shared by climbers, secondary hemi-epiphytes, and obligate epiphytes examined, may be other innovations for the ferns to have evolved into epiphytes.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 495–510.     

Nonenzymatic biotinylation of a biotin carboxyl carrier protein: unusual reactivity of the physiological target lysine

Enzyme-catalyzed addition of biotin to proteins is highly specific. In any single organism one or a small number of proteins are biotinylated and only a single lysine on each of these proteins is modified. A detailed understanding of the structural basis for the selective biotinylation process has not yet been elucidated. Recently certain mutants of the Escherichia coli biotin protein ligase have been shown to mediate "promiscuous" biotinylation of proteins. It was suggested that the reaction involved diffusion of a reactive activated biotin intermediate, biotinoyl-5'-AMP, with nonspecific proteins. In this work the reactivity of this chemically synthesized intermediate toward the natural target of enzymatic biotinylation, the biotin carboxyl carrier protein, was investigated. The results indicate that the intermediate does, indeed, react with target protein, albeit at a significantly slower rate than the enzyme-catalyzed process. Surprisingly, analysis of the products of nonenzymatic biotinylation indicates that of five lysine residues in the protein only the physiological target side chain is modified. These results indicate that either the environment of this lysine residue or its intrinsic properties render it highly reactive to nonenzymatic biotinylation mediated by biotinoyl-5'-AMP. This reactivity may be important for its selective biotinylation in vivo.     

短茎古当归根的化学成分

从短茎古当归〔Ａｒｃｈａｎｇｅｌｉｃａｂｒｅｖｉｃａｕｌｉｓ（Ｒｕｐｒ．）Ｒｃｈｂ．〕根中分得６个结晶,采用ＩＲ、ＭＳ、ＮＭＲ等方法,鉴定了４个化合物,即甲氧基欧芹素（蛇床子内酯,ｏｓｔｈｏｌ,Ⅰ）、欧前胡素（ｉｍｐｅｒａｔｏｒｉｎ,Ⅱ）、古当归素（ａｒｃｈａｎｇｅｌｉｃｉｎ,Ⅳ）、二十八烷酸（ｏｃｔａｃｏｓａｎｉｃａｃｉｄ,Ⅴ）。结晶Ⅳ和Ⅴ为首次从该植物中分出。古当归素为生物合成中最高阶段产物,是本种的特征性成分     

Mortality and behavior in Heterodera glycines juveniles following exposure to isothiocyanate compounds

For this report, we examined the toxic effects of three plant-derived isothiocyanate compounds on second-stage juveniles (J2) of Heterodera glycines. We found significant differences among compounds in the concentration required to affect nematodes, according to mortality and behavioral measurements. The concentrations required to affect behavior were significantly lower than those required for mortality. Both mortality and behavioral measurements were used to investigate whether nematodes in a quiescent state display decreased sensitivity to isothiocyanates compared with actively moving nematodes. Mortality measurements revealed that quiescent nematodes were significantly less sensitive to isothiocyanates than active nematodes. All behavioral measurements following exposure to benzyl- and phenyl isothiocyanate showed significant differences in sensitivity between quiescent and active nematodes. However, significant differences between quiescent and active nematodes were observed in only one of the five behavioral measurements following exposure to allyl isothiocyanate. These results expand the list of plant-derived compounds toxic to H. glycines and illustrate the impact of behavioral quiescence on nematode sensitivity to exogenous toxins.     

小蓬草精油对两种蚊虫的毒杀活性和成分分析

【目的】明确小蓬草Conyza canadensis ( L.) Cronq.精油的杀虫潜力及其活性成分。【方法】通过浸虫法和密闭熏蒸法测试了小蓬草精油对白纹伊蚊Aedes albopictus和致倦库蚊Culex pipiens quinquefasciatus幼虫及成蚊的毒杀活性, 并利用气相色谱 质谱联用仪（GC-MS）对精油的挥发性成分进行了定性分析。【结果】 小蓬草精油对白纹伊蚊1-4龄期幼虫及蛹的24 h LC50值分别为25.01, 45.88, 56.94, 64.60和346.23 μg/mL; 对致倦库蚊幼虫1-4龄期幼虫及蛹的24 h LC₅₀值分别为9.16, 8.65, 32.12, 43.68和197.83 μg/mL。在剂量分别为48, 64, 80, 96, 112和128 μg/cm3时, 小蓬草精油对白纹伊蚊成蚊的KT₅₀值分别为28.81, 22.31, 20.38, 17.05, 13.92和9.74 min; 对致倦库蚊的KT50值分别为34.90, 32.97, 23.97, 19.60, 15.20和10.34 min。 24 h熏蒸对白纹伊蚊和致倦库蚊成蚊的LC50值分别是75.46和99.19 μg/cm³。小蓬草精油的GC MS定性分析共分离鉴定出31种化合物, 其中单萜类物质6种, 倍半萜烯类物质17种, 含氧萜烯类6种。【结论】结果表明小蓬草精油对这两种蚊虫的毒杀活性较高, 具有深开发潜力。     

不同理化因子对雨生红球藻CG-11碳酸酐酶活性的影响

以雨生红球藻CG-11为实验藻株,探讨在不同CO2、HCO3-、Zn2＋浓度以及pH和氮磷比例条件下,藻细胞的碳酸酐酶活性对这些理化因子的响应。结果表明,通入空气实验组的碳酸酐酶活性最高,为（75.20±1.53）U·mg-1（Chla）,通入5%CO2条件下的碳酸酐酶活性为（9.96±1.43）U·mg-1（Chla）;高浓度HCO3-对碳酸酐酶活性亦具有明显抑制作用,培养液中可溶性无机碳的浓度与碳酸酐酶活性呈负相关;在实验设置的pH范围内,pH9.0时碳酸酐酶活性最高,为（62.32±3.25）U·mg-1（Chla）;适当的氮磷比与Zn2＋浓度显著提高了雨生红球藻CG-11的生长速率,碳酸酐酶的活性亦有明显提高。     

星状凤毛菊的化学成分研究

采用各种填料的色谱柱层析方法从药用植物星状凤毛菊(Saussurea stella Maxim)的全草中分离纯化出15个化合物,经波谱分析将它们的化学结构分别鉴定为2-甲氧基-4-羟基苯甲醛(1)、3-(3-甲氧基苯基)丙烯醛(2)、松脂素-4′-O-β-葡萄糖苷(3)、胡萝卜苷(4)、木犀草素(5)、金合欢素(6)、洋芹素(7)、日本椴苷(8)、3′-甲氧基木犀草素-7-O-β-葡萄糖苷(9)、洋芹素-7-O-β-葡萄糖苷(10)、槲皮素-3-O-α-L-鼠李糖苷(11)、山奈素3-O-α-L-鼠李糖苷(12)、槲皮素-5-O-β-葡萄糖苷(13)、4′-甲氧基槲皮素-5-O-β葡萄糖苷(14)和3-甲氧基山奈素-6-O-β葡萄糖苷(15)。其中化合物1～5、9～10和13～15是首次从该种植物中分离得到。     

我国23个土壤磷素淋失风险评估Ⅱ.淋失临界值与土壤理化性质和磷吸附特性的关系

从13个省（市）采取23个耕地表层土壤,通过室内模拟试验测定其磷素淋失临界值和pH、有机质、＜0.01mm、＜0.002mm、交换性钙镁、活性铁铝、磷等温吸附特性等,以建立土壤磷素淋失临界值与土壤基本理化性质和磷吸附特性之间的关系.结果表明：土壤pH＜6.0时,随土壤pH提高临界值增加,土壤pH与临界值之间呈显著的指数关系;而当土壤pH＞6.0时,随土壤pH提高临界值减小,在pH6.5左右土壤磷素淋失临界值最高.土壤磷素淋失临界值与土壤有机质、活性铁（铝）、交换性钙之间存在显著的相关,而与交换性镁、CEC、＜0.01mm、＜0.002mm、K、Qm的相关性受土壤酸碱度影响.可以通过测定土壤有机质或活性铁的含量,来计算土壤磷素淋失临界值,评价土壤磷素淋失的风险.供试的23个土壤,除了采自湖北潜江的20号水稻土存在比较大的磷素淋失风险,其余土壤发生磷素淋失的风险很小.     

Is conspecific substrate marking a long‐term external memory of previously colonized overwintering sites in Harmonia axyridis?

The multicoloured Asian ladybeetle, Harmonia axyridis (Pallas), aggregates inside dwellings during winters to survive the cold. This beetle uses chemical cues coming from congeners to select an overwintering site. Recent research has shown that they preferentially gather at places where conspecifics previously laid a substrate marking made up of saturated and unsaturated hydrocarbons. Some authors have reported that H. axyridis colonizes the same overwintering sites from 1 year to another. Herein, the hypothesis that this substrate marking is used by H. axyridis to settle in the same aggregation sites from one winter to another was tested. To this aim, the temporal modification in the chemical profile of the hydrocarbon marking was studied by performing chromatographic analyses. After 1 year, the overall profile was modified qualitatively and quantitatively: the unsaturated hydrocarbons were no longer detected while some saturated hydrocarbons were still present in large quantities. In a behavioural assay conducted in the laboratory, the 12‐month‐old marking did not induce the aggregation of H. axyridis. This result indicates that the chemical markings left by conspecifics during a previous aggregation period in an overwintering site are not sufficient to induce the gathering of the newly arriving individuals.