Cynipid gall-wasp communities correlate with oak chemistry

Host-plant association data, gathered from field surveys conducted throughout Florida and from the literature, were used to identify the specificity of cynipid gall inducers to one or more of six Quercus species that occur at Archbold Biological Station, Lake Placid, Florida, USA, including the red oaks Q. laevis, Q. myrtifolia, and Q. inopina, and the white oaks Q. chapmanii, Q. geminata, and Q. minima. Quercus myrtifolia had the highest cynipid richness and diversity (37 cynipid species, Shannon H = 3.61, Simpson's D = 0.97), followed by Q. chapmanii, Q. laevis, Q. inopina, Q. geminata, and finally Q. minima (10 species, H = 2.30, D = 0.90). All cynipid species showed strong fidelity to a particular host plant or a restricted set of host plants. An ordination of gall-wasp host associations indicated that the cynipid communities of each oak species were distinct and specific to a given oak species. Leaf samples taken from each oak species were analyzed for condensed and hydrolyzable tannins, total phenolics, lignin, cellulose and hemicellulose, nitrogen, and carbon. All of these chemical traits, with the exception of carbon, differed by oak species, and the differences were strongly correlated with the axes of the cynipid--species ordination. These results suggest that gall-wasp occurrence is influenced by oak chemistry and imply that experimental studies of cynipid gall inducers that examine host-plant chemistry and female oviposition choice and larval performance will yield useful insights.     

Variation in tannin activity of acorns of seven species of central florida oaks

Acorns of seven sympatric species of oaks (Quercus spp.) occurring in central Florida were compared for protein-precipitating ability (PPA). Husks and cotyledons of green and ripe acoms were analyzed. Few significant differences were found between green and ripe acorns of the same species. Cotyledons were significantly higher than husks in PPA in most of the species compared. All species exhibited high intraspecific variability in PPA. Significant differences between species were found in green and ripe cotyledons and in green husks. With the exception ofQ. minima, PPA of ripe cotyledons was higher in the subgenusErythrobalanus (red oaks) than the subgenusQuercus (white oaks).     

亚热带植物叶蛋白酶活性研究

为探索新的植物蛋白酶,采用改进的Kun it蛋白酶活性测定法,对分属61科的190种亚热带植物叶中的蛋白酶活性进行了分析。结果表明,叶蛋白酶活性低于1 000 U/g的植物有133种,介于1 000~2 000 U/g的植物有43种,高于2 000 U/g的植物有14种;在61科植物中,以槭树科和壳斗科植物叶中的蛋白酶活性较高;叶中蛋白酶活性最高的植物是元宝槭和红果罗浮槭,叶中蛋白酶活性分别为5 228 U/g和5 092 U/g,与菠萝果的蛋白酶活性(6 184 U/g)较为接近,具有很高的研究和开发价值。     

壳斗科柯属及厚鳞柯植物资源研究现状及展望

阐述壳斗科柯属及厚鳞柯植物开发利用价值及化学成分鉴定的研究现状,鉴于市场上伪劣厚鳞柯种子泛滥,归纳食品和中药材真伪识别技术研究现状,并展望厚鳞柯种子研究方向。对厚鳞柯种子中各类化合物进行结构鉴定,探讨厚鳞柯种子有无药用价值;建立真伪识别模型,找到区分真伪厚鳞柯种子的关键化学成分;探求指标性成分定性定量测定方法,并建立厚鳞柯种子质量标准。以期为食药监管和壮药资源开发利用提供参考。     

Do defoliation and subsequent phytochemical responses reduce future herbivory on oak trees?

Perennial plants are thought to respond to partial or complete defoliation by producing new foliage that is less susceptible to herbivores because of induction of allelochemicals. Here, I tested this hypothesis by manually removing primary foliage from branches ofQuercus emoryi (Fagaceae) at two different times in the season and monitoring changes in protein and tannin levels and the amount of herbivory relative to control branches. New, secondary leaves had 2.5 × greater hydrolyzable tannin content than mature foliage of control branches. Condensed tannins, which constitute a relatively low fraction of leaf mass, were lower, while protein content was temporarily greater, in new secondary leaves relative to mature leaves. Despite large increases in hydrolyzable tannins, herbivory levels were greater on refoliated branches than on control branches. New foliage is susceptible to herbivory regardless of when it is produced in the season, possibly because lower toughness and higher water content override any induced or developmentally related changes in allelochemistry. My results do not support the hypothesis that postherbivore changes in phytochemistry protect perennial plants from future herbivory, at least within a growing season.     

Quercus ilex L.: A rich source of polyacylated flavonoid glucosides

From the methanolic extract of Quercus ilex leaves a series of acylated flavonol glucosides were identified, among them five new naturally occurring compounds. The constituents, which were all p-coumaroyl glucosides of kaempferol, were characterised either as pure compounds or as inseparable, complicated mixtures of cis and trans isomers. Their complete structure elucidation was done by 2D NMR (COSY, HSQC, HMBC, ROESY) and HPLC-DAD-MS analyses. 2D NMR spectral data allowed the discrimination between different isomers. Quantitative analysis of the methanolic extract of the plant revealed that it is a rich source of acylated flavonoid glucosides (1.22%). Under the experimental conditions chosen HPLC-DAD-MS analyses showed that cis isomers are less polar than trans isomers and their detailed identification, the first in the literature so far, could serve as a tool for the detailed characterisation of analogous isomers by HPLC-DAD-MS in other complicated plant extracts.     

八种野生壳斗科植物果实营养成分的分析研究

对采自井冈山山区的甜槠、苦槠、锥栗、茅栗、青冈、华南石栎、红钩栲、多穗柯等八种野生壳斗科植物果实的营养成分进行分析,结果表明其果实营养成分均以淀粉、糖类为主,同时含有丰富的蛋白质、脂肪、维生素以及Ca、Mg、Fe等多种人体所必需的矿物质元素,并依据所测营养指标对其营养品质作出了初步评价.     

Characteristics of beechnut oil (Fagus orientalis lipsky) of turkish origin

The characteristics of beechnut oil (Fagus orientalis Lipsky) of Turkish origin were investigated. The fatty acid composition was determined by capillary gas chromatography. The oil showed the characteristics of a semidrying oil.