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At least 631 records · Page 35Linked to original sources
PubMed2000

Volatiles released from oak, a host tree for the bark beetle Scolytus intricatus.

Volatile compounds emitted in different phases of oak (Quercus robur) development (bark, unopened buds, young developing leaves, and blossoms) were analyzed with the aim of finding possible host-plant attractants for the European oak bark beetle, Scolytus intricatus. Complex mixtures of aliphatic, aromatic, and terpenoid compounds were identified in the samples. (E)-2-Hexenal and hexanal dominated in samples of bark. In buds, (Z)-3-hexenyl acetate formed a substantial part of the mixture. In both leaves and blossoms (E,E)-alpha-farnesene was the main component.Volatiles released from oak twigs and branches during both the maturation feeding and construction of maternal galleries by Scolytus intricatus were also analyzed. Most compounds found in the samples from females' and males' maturation feeding were identical. High contents of anisole, (E)-beta-ocimene, alpha-copaene, one unidentified sesquiterpenic hydrocarbon C(15)H(24) and beta-caryophyllene were found in both samples of twigs attacked by beetles. During the construction of maternal galleries by bark beetles in oak logs, monoterpene hydrocarbons such as p-cymene, (E)-beta-ocimene, and gamma-terpinene, and sesquiterpenes alpha-copaene and beta-caryophyllene were released in large quantities. No new compound appeared when males were added to the log with feeding females.

Journal Article↗
PubMed2002

Anticancer and antithrombin activity of Russian plants.

A chromogenic bioassay was utilized to determine the antithrombin activity of the methylene chloride and methanol extracts prepared from forty-five plants of Russia. Mouse leukemia cells (L1210) were utilized to screen these extracts for activity against cancer. The results indicated that eight plant extracts demonstrated 90% or higher activity in the inhibition of thrombin. Also, nine methanol extracts demonstrated activity of 90% or higher in the inhibition of mouse leukemia L1210 cells. The methanol extracts of Quercus robur and Sanguisorba officinalis demonstrated high activity against both thrombin and cancer.

Animals↗
PubMed2002

Antioxidant activity in medicinal plants associated with the symptoms of diabetes mellitus used by the indigenous peoples of the North American boreal forest.

Thirty-five plant species were selected from the published literature as traditionally used by the Indigenous Peoples of the boreal forest in Canada for three or more symptoms of diabetes or its complications. Antioxidant activities in methanolic extracts support the contribution of these traditional medicines in a lifestyle historically low in the incidence of diabetes. In a DPPH assay of free radical scavenging activity 89% of the methanol extracts had activity significantly greater than common modern dietary components, 14% were statistically equal to ascorbic acid and 23% had activities similar to green tea and a Trolox positive control. Superoxides produced with an NBT/xanthine oxidase assay found scavenging was significantly higher in 29% of the species as compared with the modern dietary components and Trolox. The methanol extracts of Rhus hirta, Quercus alba and Cornus stolonifera performed similarly to green tea's in this assay. Assessment of peroxyl radical scavenging using a DCF/AAPH assay showed 60% of the plant extracts statistically similar to Trolox while R. hirta and Solidago canadensis extracts were greater than green tea, ascorbic acid and Trolox. The majority of the species (63 and 97%, respectively) had scavenging activities similar to ascorbic acid in the superoxide and peroxyl radical scavenging assays.

Antioxidants↗
PubMed1999

Pharmacological screening of the anti-ulcerogenic effects of some Jordanian medicinal plants in rats.

Ethanolic extracts of 18 medicinal plants traditionally used in Jordan for the treatment of gastric ulcers were evaluated for their possible anti-ulcer activity. Among the tested plants, 12 extracts lowered the severity of ethanol-induced gastric damage in rats with curative ratios ranging from 62.9 to 99.5%. The most active extract was that of Quercus coccifera, with a curative ratio of 99.5%.

Animals↗
PubMed2000

Annual fluctuation in amplitudes of daily variations of electrical signals measured in the trunk of a standing tree.

Electrical potential differences between electrodes inserted in eight selected sites of the trunk of a Turkey oak (Quercus cerris) and the ground have been recorded continuously since November 1997. The mean amplitudes of daily electric variations were determined for time intervals when the meteorological and atmospheric electricity conditions were undisturbed. It was found that the mean daily amplitudes show a characteristic annual fluctuation. Both in 1998 and in 1999 two peaks were observed: the first maximum appears suddenly about the end of March, and the second one was seen in late June, July. Between November and March the mean amplitudes were smaller by about one order of magnitude.

Circadian Rhythm↗
PubMed2001

[The Lateglacial sequence of the Etelles (northern French Alps): climate instability and vegetation dynamics].

A detailed pollen analysis has been conducted in a new sedimentary sequence taken at Les Etelles (700 m), in the hill vegetation belt in the Chaîne des Hurtières (Northern French Alps). The Lateglacial history of the vegetation has been supported by 10 AMS datings. Variations in relative abundance of main pollen taxa were compared with variations in [symbol: see text] 18O in Swiss lacustrine sediments and with the GRIP ice-core record. Those highlight how the vegetation reacted to minor climatic oscillations. The Lateglacial spread of Quercus, Alnus and Corylus in the region is confirmed, thus allowing a new interpretation of some Lateglacial sedimentary sequences at an adjacent region (Bas-Dauphiné).

Climate↗
PubMed2001

Digestibility, N balance and blood metabolite levels in Alpine goat wethers fed either water oak or shining sumac leaves.

Eight Alpine wethers (8-9 months of age, 27.5+/-1.10kg body weight (BW)) were randomly assigned to consume, free-choice, either shining sumac (Rhus copallina) or water oak (Quercus nigra) leaves as a sole diet. Leaves were collected and dried prior to feeding. A 14-day adaptation period was followed by a 4-day total fecal and urine collection. Chemical composition (%) of the fed water oak and shining sumac leaves revealed similar levels of OM (95.9 and 94.1) and N (1.54 and 1.42) but higher concentrations of cell wall fractions, NDF (54.8 and 31.2) and ADF (34.5 and 26.4), in water oak than shining sumac. Body weight of wethers differed between treatments, although this was not reflected in DM intake. Average daily intake values were 616g DM, 589g OM and 9.3g N. NDF intake was significantly lower (P=0.002) in goats-fed shining sumac than in those that consumed water oak (192 versus 330g). Daily fecal output of all components was higher (P<0.05) in water oak than shining sumac-fed goats. Apparent digestibilities (%) of all components were significantly lower in water oak than shining sumac-fed animals (DM 41 versus 63, OM 42 versus 64, NDF 24 versus 37, and N 27 versus 38). Urinary N excretion, N balance and concentrations of protein, plasma urea nitrogen (PUN) and glucose in the blood were similar between diets, averaging 2.6g N per day, 0.45g per day, 85.5mg/ml, and 14.1mg/dl, respectively. The results of this trial suggest that shining sumac is utilized better by goats than water oak. The use of dried leaves in this experiment may have led to possible negative effects on nutrient characteristics that animals consuming fresh leaves may not experience.

Journal Article↗
PubMed2003

[Role of man in the history of vegetation of the Ellero valley (maritime Alps, Italy)].

The pollen analysis of a sediment core from a peat bog (Rifugio Mondovi) at the mountain belt (1760 m) in the Ellero Valley (Italian Maritime Alps) shows the postglacial vegetation history. The sequence starts at 12,000 BP during a peak of pine pollen; this first phase shows a low representation of birch and the presence of Tilia. Younger Dryas is characterised by increasing percentages of Artemisia, showing the presence of deciduous Quercus, fir and beech. Elm appears at the beginning of the Holocene during the second pine peak (9800 BP). A 3000-year hiatus is present. Sedimentation resumes at 6000 BP in a Rhododendron fir-wood. The present timberline at 1500 m, at the limit of the beech wood, is a result of the decline of the fir-wood at 2600 BP, which allowed an expansion of beech. During this period, there was a continual increase in Gramineae and deciduous oak and the first occurrences of evergreen oak are observed. The development of larch occurs at 1800 BP, together with walnut, chestnut, cereals and vine.

Anthropology↗
PubMed2004

Controversy over Hygrophorus cossus settled using ITS sequence data from 200 year-old type material.

Sowerby described Agaricus cossus in 1799. The fungus possessed a smell, resembling that of a wounded larva of Cossus cossus (Lepidoptera). The species belongs in Hygrophorus, and since more than one white Hygrophorus species has this distinctive smell the epithet cossus has been variously interpreted. The complete internal transcribed spacer (ITS) region of the original type collection made in 1794, preserved in the Royal Botanic Gardens Kew herbarium, was successfully sequenced. Comparison with the ITS sequences from four other white aromatic-acidulous smelling Hygrophorus species, including the type specimen of H. quercetorum, showed that H. cossus is a species associated with Quercus and an older name for H. quercetorum. The differences in basidiome colouration developing with age and host-tree association appear to be the most useful characters to discriminate between the four species with a Cossus cossus smell. A table of morphological and ecological characters is provided.

Agaricales↗
PubMed2004

Uniting Tricholoma sulphureum and T. bufonium.

The taxonomic status and relationship of Tricholoma sulphureum and the similar T. bufonium were investigated using different sets of characters. These included morphological data on fruit bodies, ecological and chorological data, and analysis of the sequence data obtained for the ITS of basidiomes of different ecological and geographic origin. Moreover, the ectomycorrhizas formed by T. bufonium on Abies alba and Quercus sp. were characterised, and anatomical features compared with those of T. sulphureum mycorrhizas on coniferous and broad-leaved host trees. Our results revealed extensive ITS variation in members of the T. sulphureum group, but this variation was not correlated with morphology, ecology, or geographical distribution. We conclude that T. bufonium cannot be maintained as an autonomous taxon and should be treated as an infraspecific variant of T. sulphureum.

Abies↗
PubMed2003

Identification, measurement and interpretation of tree rings in woody species from mediterranean climates.

We review the literature dealing with mediterranean climate, vegetation, phenology and ecophysiology relevant to the understanding of tree-ring formation in mediterranean regions. Tree rings have been used extensively in temperate regions to reconstruct responses of forests to past environmental changes. In mediterranean regions, studies of tree rings are scarce, despite their potential for understanding and predicting the effects of global change on important ecological processes such as desertification. In mediterranean regions, due to the great spatio-temporal variability of mediterranean environmental conditions, tree rings are sometimes not formed. Often, clear seasonality is lacking, and vegetation activity is not always associated with regular dormancy periods. We present examples of tree-ring morphology of five species (Arbutus unedo, Fraxinus ornus, Quercus cerris, Q. ilex, Q. pubescens) sampled in Tuscany, Italy, focusing on the difficulties we encountered during the dating. We present an interpretation of anomalies found in the wood structure and, more generally, of cambial activity in such environments. Furthermore, we propose a classification of tree-ring formation in mediterranean environments. Mediterranean tree rings can be dated and used for dendrochronological purposes, but great care should be taken in selecting sampling sites, species and sample trees.

Climate↗
PubMed2001

Sorption of lipophilic organic compounds to wood and implications for their environmental fate.

The sorption from water to wood (KWood) of 10 organic chemicals (log KOW, 1.48-6.20) was experimentally determined for oak (Quercus robur) and basket willow (Salix viminalis). Linear regression yielded log KWood = -0.27 (+/- 0.25) + 0.632 (+/- 0.063) log KOW for oak (r = 0.90, n = 27) and log KWood = -0.28 (+/- 0.40) + 0.668 (+/- 0.103) log KOW for willow (r = 0.79, n = 27). According to an equilibrium-partitioning model, wood should be an important storage compartment for lipophilic environmental chemicals, but this is contrary to analytical results. Diffusive uptake from air into wood was estimated to be a relevant transport process only for chemicals with a high KAW. Uptake of chemicals from soil via xylem into stem was simulated with a dynamic one-compartment model. This pathway seems to be important for chemicals with low and intermediate lipophilicity. In large trees, the chemicals are retained for a long time. If metabolism inside the stem occurs, wood can serve as a "safe sink" for environmental chemicals. This might be of use in phytoremediation.

Air↗
PubMed2006

Understanding the native Californian diet: Identification of condensed and hydrolyzable tannins in tanoak acorns (Lithocarpus densiflorus).

The tanoak (Lithocarpus densiflorus) acorn was a staple food in the Native American diet and is still used in traditional dishes. Acorns from the genus Quercus have been shown to contain a large range of hydrolyzable tannins. However, neither hydrolyzable nor condensed tannins have been characterized in tanoak acorns. The aim of this study was to identify the full range of hydrolyzable and condensed tannins in extracts of tanoak acorns using liquid chromatography/electrospray ionization-mass spectrometry/mass spectrometry. Condensed tannins were identified as B type oligomers of (epi)-catechin (procyanidins) with a degree of polymerization up to six. Oligomers up to and including tetramers were identified by UV spectra and MS detection whereas pentamers and hexamers were detected only by MS. The total concentration of condensed tannins was 464 mg/100 g acorn pericarp. The concentration of propocyanidin monomers, dimers, trimers, and tetramers in acorn pericarp (mg/100 g acorn pericarp) were 95 +/- 10.9, 148 +/- 35.0, 90 +/- 17.9, and 131 +/- 1.9, respectively. No procyanidins were found in the acorn cotyledon tissue. A total of 22 hydrolyzable tannins were identified in methanolic extracts of acorn cotyledon tissue. Gallic acid derivatives predominated and included galloylated esters of glucose, hexahydrodiphenoyl esters of glucose, and methylated gallates. Galloylated esters of glucose were present as isomers of galloyl glucose, digalloyl glucose, and trigalloyl glucose. Mass spectral fragmentation patterns indicate the presence of one gallic acid-galloyl glucose isomer and two gallic acid-digalloyl-glucose isomers. No isomers of tetragalloyl glucose and pentagalloyl glucose were identified. Ellagic acid and ellagic acid pentoside were also identified.

California↗
PubMed2003

Discovery, characterization, and structure-activity relationships studies of proapoptotic polyphenols targeting B-cell lymphocyte/leukemia-2 proteins.

Among the most promising chemopreventive agents, certain natural polyphenols have recently received a great deal of attention because of their demonstrated inhibitory activity against tumorigenesis. In view of their anticancer properties, these compounds also hold great promise as potential chemotherapeutic agents. However, to translate these chemopreventive agents into chemotherapeutic compounds, their exact mechanisms of action must be delineated. By using a multidisciplinary approach guided by modern nuclear magnetic resonance spectroscopy techniques, fluorescence polarization displacement assays, and cell-based assays, we have begun to unravel the mechanisms of actions of certain polyphenols such as Gossypol (a compound from cotton seed extracts) and Purpurogallin (a natural compound extracted from Quercus sp. nutgall) and their derivatives. Our findings suggest that these natural products bind and antagonize the antiapoptotic effects of B-cell lymphocyte/leukemia-2 (Bcl-2) family proteins such as Bcl-x(L). Our in vitro and in vivo data not only open a window of opportunities for the development of novel cancer treatments with these compounds but also provide structural information that can be used for the design and development of novel and more effective analogues.

Antineoplastic Agents↗
PubMed1999

Biotransformation of the trichoderma metabolite 6-n-pentyl-2H-pyran-2-one (6PAP) by selected fungal isolates

A variety of fungi were tested for their ability to transform the antifungal Trichoderma metabolite 6-n-pentyl-2H-pyran-2-one (6PAP) (1). Three Penicillium isolates, a Sclerotinia isolate, and a Fusarium isolate were all able to rapidly metabolize 1 and gave mixtures of isomers of monohydroxylated 1 and, in some cases, products resulting from further oxidation to carboxylic acids. Among these products were four previously unidentified metabolites (6, 7, 8, and 9) which were isolated and characterized by NMR spectroscopy. Sphaeropsis sapinea, Ophiostoma quercus, Ophiostoma piceae, a Verticillium sp., and two additional Fusarium isolates were unable to metabolize 1 efficiently.

Journal Article↗
PubMed1998

Identification of Armillaria field isolates using isozymes and mycelial growth characteristics.

This research was conducted to develop procedures based on mycelial growth characteristics and patterns of esterase (EST) and polyphenol oxidase (PPO) production by diffuse mycelia for identification of Armillaria field isolates from Quercus-Carya-Pinus forests in the Ozark Mountains (central USA). The 285 isolates collected were first identified by standard diploid-haploid pairing tests as A. gallica, A. mellea, or A. tabescens. A strong PPO band was diagnostic for A. gallica. All A. mellea isolates tested and 91% of the A. tabescens isolates tested were distinguished based on production of EST bands in three standardized R f ranges. A procedure based on mycelial growth and morphology on tannic acid medium (TA) at 24 degrees C and on malt extract medium (ME) at 33 degrees C correctly identified 98% of A. gallica isolates and all A. mellea and A. tabescens isolates. On TA, A. gallica grew slowest. On ME, A. mellea grew slowest: mycelial morphology differed among species; A. gallica typically stained the agar and produced an appressed/submerged growth pattern with concentric bands of decreasing hyphal density, A. mellea typically did not stain the agar and produced round mycelia with smooth margins and abundant aerial hyphae, A. tabescens typically stained the agar and grew appressed/submerged with very irregular margins and patchy hyphal density. These are the first published systems evaluating the potential for identifying Armillaria field isolates based on their mycelial growth characteristics and EST and PPO complements.

Journal Article↗
PubMed2002

2-Methyl-(Z)-7-octadecene: sex pheromone of allopatric Lymantria lucescens and L. serva.

Our objective was to identify the sex pheromone of Lymantria lucescens and Lymantria serva (Lepidoptera: Lymantriidae), whose larvae defoliate, respectively, Quercus spp. in temperate regions and Ficus spp. in the subtropics. Coupled gas chromatographic-electroantennographic (GC-EAD) detection analyses of pheromone gland extracts revealed one EAD active compound produced by female L. lucescens and by female L. serva. This was identified as 2-methyl-(Z)-7-octadecene (2me-Z7-18Hy) by retention index calculations on DB-5, DB-23, and DB-210 columns and by comparative GC-mass spectrometric (MS) and GC-EAD analyses of the insect-produced candidate pheromone and synthetic 2me-Z7-18Hy. In field experiments, traps baited with 2me-Z7-18Hy captured male L. lucescens near Toyota City, Japan, and male L. serva in Taipei, Taiwan. Allopatric distribution of L. lucescens and L. serva seems to allow both species to use the same sex pheromone without compromising its specificity.

Alkenes↗