Showing papers on "Bark published in 2008"

Methyl jasmonate and oxalic acid treatment of Norway spruce: anatomically based defense responses and increased resistance against fungal infection.

Abstract: To study the effect of chemical pretreatment on conifer resistance, 13-year-old Norway spruce (Picea abies (L.) Karst.) trees were treated with methyl jasmonate (MJ) or oxalic acid (OxA) on the outer bark and inoculated with the pathogenic blue-stain fungus Ceratocystis polonica (Siem.) C. Moreau 4 weeks later. Both chemicals significantly reduced symptoms of fungal infection, but MJ was more effective than OxA (51 versus 18% reduction in length of necrotic lesions in the phloem relative to untreated control trees). Anatomical examination of treated stem tissues showed that MJ induced extensive formation of traumatic resin ducts in the xylem and extra polyphenolic parenchyma (PP) cells in the secondary phloem between the cambium and the regular annual PP cell layer. No traumatic resin ducts were formed after treatment with OxA, and the coverage of extra PP cells in OxA-treated tissues was not significantly higher than in the controls. The anatomically based defense reactions induced by MJ were similar to the reactions observed after pathogen infection, mechanical wounding and bark beetle attack. Neither MJ nor OxA had apparent phytotoxic effects on Norway spruce at the concentrations used, with needle and stem tissues of all trees appearing normal without visible symptoms of toxicity. However, trees treated with MJ had 30% less radial sapwood growth than control trees. In conclusion, MJ treatment of Norway spruce appears to have practical potential as a tool for increasing plant resistance to fungal infection, but with a modest reduction in sapwood growth.

Review Essay: Human Security: The Dog That Didn't Bark

Abstract: THE HISTORY OF THE RADICAL CHALLENGE of ‘human security’– from the first usage of the term in the United Nations Development Programme’s 1994 Human Development Report until the present time – is often written in terms that pose the centrality of the struggle between traditional, state-based, interest-based approaches and new, deterritorialized, values-based approaches that focus on individual human needs. For some authors, the struggle is at the heart of how we conceive of international relations and questions of security, and one that, after 9/11 and with the ongoing disaster of Iraq, is more important than ever. This struggle for the heart and soul of global policymaking is often posed as one between two different ‘paradigms’, two entirely different outlooks on the world, one paradigm reproducing current power relations and inequalities and insecurities, the other challenging such a view, recognizing the interconnectedness, interdependence and mutual vulnerabilities of security threats and the need for collective, collaborative, human-centred responses. This review article suggests that 14 years after human security was first taken up by the United Nations, its integration into the policymaking and policy practices of leading Western states and international institutions has revealed that talk of two different ‘paradigms’ – the radical counter-position of ‘individual’ and ‘state-based’ approaches, or between ‘critical theory’ and Review Essay

Seasonal and tissue age influences on endophytic fungi of Pinus tabulaeformis (Pinaceae) in the Dongling Mountains, Beijing

Abstract: Endophytic fungi associated with Pinus tabulaeformis Carr. were investigated in the Dongling Mountains of Beijing. A total of 16,200 tissue segments of P. tabulaeformis from four sample collections were processed, and 10,659 fungal isolates were recovered. The overall colonization and isolation rates of endophytic fungi from high to low were spring > winter > autumn > summer and in different tissues were bark > needle > xylem, irrespective of sampling seasons. The colonization rates of endophytic fungi of needles increased with age in the four sample collections. There were no significant differences of the colonization rates of endophytic fungi among 1-, 2-, and 3-year-old bark and xylem, except for significantly lower colonization rates in 1-year-old bark than in 2- and 3-year-old bark in summer. A similar trend of the isolation rates of endophytic fungi occurred. A total of 24 fungal taxa were recorded, of these five taxa Alternaria alternata, Leptostroma sp., Pestalotiopsis besseyi, Phoma lingam, and Phomopsis archeri, were consistently isolated as the common fungi in each sample collection. Our results suggest that some fungi show a certain degree of tissue recurrence or specificity, and the composition of endophytic assemblages is not conspicuously influenced by the seasonal factor.

Cytotoxic constituents from the bark of Salix hulteni

Abstract: Eight compounds were isolated from the bark of Salix hulteni. Based on spectral data, the isolated compounds were identified as 4-hydroxyacetophenone (1), naringenin (2), aromadendrin (3), catechin (4), picein (5), sachaliside 1 (6), 1-p-coumaroyl-beta-D-glucoside (7), and dihydromyricetin (8). Their cytotoxic activities against brine shrimp and a human lung cancer cell line (H1299) were evaluated.

Saccharomyces arboricolus sp. nov., a yeast species from tree bark.

Abstract: Seven species are currently included in the genus Saccharomyces Meyen ex Reess as redefined recently by Kurtzman (2003), based on multigene sequence analysis (Kurtzman & Robnett, 2003). During the investigation of the diversity of ascomycetous yeasts associated with plant materials from China, three strains, H-6 T , ZX-15 and ZX20, isolated from the bark of broadleaf trees, were found to represent a novel species of the genus Saccharomyces by physiological characterization, rRNA gene sequencing and electrophoretic karyotyping. Yeast strains living in bark were isolated by using the enrichment method. Pieces of bark with or without exudates from independent trees were cut with a sterile scalpel and placed into sterile plastic tubes containing 3 ml liquid enrichment medium. The medium was made according to Sniegowski et al. (2002) with minor modifications, containing (w/v) 0.3% yeast extract, 0.3% malt extract, 0.5% peptone, 0.5% sucrose, 0.5% galactose, 7.6% (v/v) ethanol, 200 mg chloramphenicol ml 21 and 1 ml 1 M HCl per litre. The cultures were incubated at room temperature without shaking for 7 to 14 days. Aliquots (100 ml) of the 10 22 to 10 24 diluted enrichment

Bark content estimation in poplar (Populus deltoides L.) short-rotation coppice in Central Italy

Abstract: Differences in bark and wood content in woody biomass directly affect its quality and economic value as an energy source. In order to estimate the quality of biomass before harvesting, an allometric regression of bark percentage of total aboveground biomass and DHB (diameter at 1.30 m height) was developed in a 2-year poplar short-rotation coppice system in Central Italy. Firstly, a relationship between mean diameter and bark content percentage was established in 1 cm-wide sections belonging to all diametric classes. The model of best fit for these stem cylindrical sections was an equation y=ax−b. Following this, sample stems (of which we measured DHB) were collected and divided into sections belonging to a diameter class. Fresh and dry matter were determined for each class. Using the first equation, bark content was calculated separately for all classes. Thereafter, a second equation between bark content in the whole stem and DHB was developed. The best fitting equation for the whole stem was y=cx−d. Bark content in the whole stem ranged from 33.9–31.4% in large-sized DHB stems to 15.1–12.5% in smallest stems, depending on their moisture content. Bark content decreased rapidly in the small diametric classes until DHB reached 4 cm. Thereafter, the ratio of reduction of bark percentage dropped.

Chemical constituents from Swietenia macrophylla bark and their antioxidant activity.

Abstract: Chemical constituents of the bark of Swietenia macrophylla King (Meliaceae) was investigated not only to develop further bark utilization but also to understand the biochemical function of the bark in the forest environment. A new phenylpropanoid-substituted catechin, namely, swietemacrophyllanin [(2R*,3S*,7"R*)-catechin-8,7"-7,2"-epoxy-(methyl 4",5"-dihydroxyphenylpropanoate)] (1) was isolated from the bark of S. macrophylla together with two known compounds, catechin (2) and epicatechin (3). The structure of 1 was elucidated by spectroscopic data and by comparison of the NMR data with those of catiguanins A and B, phenylpropanoid-substituted epicatechins. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity of the isolated compounds indicated that all of the three compounds have strong activity compared with trolox as a reference. Swietemacrophyllanin (1) had the strongest activity with a 50% inhibitory concentration (IC50) value of 56 microg mL(-1).

Phytochemical and antimicrobial screening of extracts of Aquilaria agallocha Roxb.

Abstract: Aquilaria agallocha Roxb. is an endangered economic plant used for production of agar wood worldwide. The aqueous and methanol extracts along with dry powder of leaf and bark of the plant was screened for the presence of phytochemicals. Also they were tested for antibacterial activity against pathogenic bacteria such as Shigella flexneri, Bacillus brevis, Pseudomonas aeruginosa and Bacillus subtilis. The result indicates the presence of alkaloids, anthroquinones, triterpenoids, tannins, fixed oils and fats and glycosides in methanol extracts whereas saponins, fixed oils and fats, alkaloids and triterpenoids were found in the aqueous extracts. The highest alkaloid content was in the aqueous extract of the bark (0.06%). The saponin content was found to be high in the leaf powder (0.169%). The bark powder contained 0.067% glycosides while the leaf powder had 0.036%. The leaf powder had the highest amount of carbohydrates (19.42 mg/g dry weight), protein (24.37 mg/g DW) and amino acids (12.1 mg/g DW). The methanol extract of the leaf gave the highest zone of inhibition against B. subtilis (19 mm). All other extracts showed moderate zones of inhibition (14 - 18 mm) against all the bacteria tested. The present study has proved the usefulness of agarwood tree for medicinal purposes. The presence of phytochemicals indicates its potential as a source of useful drugs.

Antimicrobial activity of essential oils of xylopia aethiopica

Abstract: Xylopia aethiopica is a medicinal plant of great repute in West Africa which produces a variety of complex chemical compounds. The fresh and dried fruits, leaf, stem bark and root bark essential oils showed various degrees of activity against the Gram positive bacteria, Bacillus subtilis and Staphylococcus aureus, the Gram negative bacteria Pseudomonas aeruginosa and the yeast-like fungus Candida albicans, using the cup plate method,. However, none of the oils showed activity against Escherichia coli.

Comparative Study of Leaf and Stem Bark Extracts of Parkia Biglobosa Against Enterobacteria

Abstract: Hydroethanolic and aqueous extracts of leaf and stem bark of Parkia biglobosa (Jacq) Benth. (Mimosaceae) were tested against clinical isolates Escherichia coli, Salmonella typhi, Shigella dysenteriae and Enterococcus faecalis, and corresponding collection strains E. coli CIP 105 182, Salmonella enterica CIP 105 150, Shigella dysenteriae CIP 54-51 and Enterococcus faecalis CIP 103 907. Discs of Gentamicin, a broad spectrum antibiotic were used as positive controls. The results showed that all the extracts possess antimicrobial activities. A comparative study of the antibacterial activity of the leaves and that of the bark showed that for all the tested microorganisms, the hydroalcoholic extract of the bark is more active than the aqueous extract of the leaf. The hydroethanolic extract of the leaves is as effective as the aqueous extract of the stem bark prescribed by the traditional healer, suggesting it is possible to use leaves other than the roots and bark. The phytochemical screening showed that sterols and triterpenes, saponosides, tannins, reducing compounds, coumarins, anthocyanosides, flavonosides are present in both bark and leaf but in different concentrations.

Antioxidant activity of the ethanolic extract from the bark of Chamaecyparis obtusa var. formosana

Abstract: BACKGROUND:Chamaecyparis obtusa var. formosana (Taiwan hinoki) is an endemic conifer in Taiwan and the purpose of this study is to evaluate the antioxidant activity of various fractions obtained from the bark of this plant material. The ethanolic extract of the bark was sequentially separated into three fractions, including n-hexane, ethyl acetate and ethanol soluble fractions, by liquid–liquid partition. Then the antioxidant activities of crude extract and three fractions along with 13 subfractions obtained from the ethyl acetate (EA) soluble fraction were tested for several antioxidant assays. RESULTS: The total phenolic content of the samples varied from 27.71 to 102.86 mg GAE g−1 dry weight for fractions, and from 49.94 to 206.46 mg GAE g−1 for subfractions (where GAE is milligrams of gallic acid per gram of extract). The Trolox equivalent antioxidant capacity (TEAC) ranged from 0.15 to 0.26 mmol L−1 Trolox equivalents. The EA soluble fraction was found to be the best antioxidant-rich fraction in terms of DPPH and reducing power assays. With further data analysis it was found that there was a positive correlation between the total phenolic content of extracts and TEAC is R2 = 0.61. CONCLUSION: Results from various antioxidant assays showed that the EA fraction possessed strong antioxidant activity. This would provide additional information about the antioxidant activity of bark extract of this plant species. Copyright © 2008 Society of Chemical Industry

Biologically Active Natural Products of the Genus Callicarpa

Abstract: About 20 species from Callicarpa have reported ethnobotanical and ethnomedical uses, and several members of this genus are well known in the traditional medical systems of China and South Asia. Ethnomedical reports indicate their use in the treatment of hepatitis, rheumatism, fever, headache, indigestion, and other ailments. Several species of Callicarpa have been reported to be used against cancer (e.g., Callicarpa americana root to treat skin cancer and Callicarpa rubella bark to treat tumors of the large intestine). Extracts from about 14 species in this genus have been evaluated for biological activity, including antibacterial, antifungal, anti-insect growth, cytotoxic, and phytotoxic activities. In addition to amino acids, benzenoids, simple carbohydrates, and lipids, numerous diterpenes, flavonoids, phenylpropanoids, phytosterols, sesquiterpenes, and triterpenes have been detected in or isolated from the genus Callicarpa. The essential oils of Callicarpa americana have recently been reported to have antialgal and phytotoxic activities, and several isolates from this species (and C. japonica) were identified as contributing to the mosquito bite-deterrent activity that was first indicated by folkloric usage. Recent bioassay-guided investigations of C. americana extracts have resulted in the isolation of several active compounds, mainly of the clerodane diterpene structural type.

Stem mortality of Acacia nigrescens induced by the synergistic effects of elephants and fire in Kruger National Park, South Africa

Abstract: One manner in which elephants utilize trees is by removing their bark. This type of utilization is concentrated on the largest trees in the landscape. The role of bark removal in increasing the vulnerability of large trees to fire and the mechanism through which fire damage is mediated were investigated in Kruger National Park, South Africa, by experimentally removing bark and burning Acacia nigrescens stems with diameters ranging between 30 and 68 mm. Also, field surveys were conducted subsequent to natural fires in order to investigate mortality patterns of large trees with dbh greater than 15 cm with bark removed by elephants. An increasing probability of mortality was associated with increasing amounts of bark removal but only if trees were burned. When trees had bark removed but were not burnt, simulating damage only to cambium and phloem, none of the 12 treated stems died in the 4-mo period over which the experiment ran. Moreover, low levels of cambium damage were detected in large burned stems. This suggests that bark removal increases fire-induced xylem damage and that this damage contributes towards stem mortality. In a survey of 43 7 large trees, bark removal by elephants was frequent on large stems (44%) and larger trees have greater amounts of bark removed. Post-fire mortality of large trees was significantly associated with increasing bark removal and stem diameter. These results indicate that bark removal by elephants increases the vulnerability of stems to fire. resulting in mortality of large stems otherwise protected from fire.

Blacks Mountain Experimental Forest : bark beetle responses to differences in forest structure and the application of prescribed fire in interior ponderosa pine

Abstract: Mechanical thinning and the application of prescribed fire are commonly used tools in the restoration of fire-adapted forest ecosystems. However, few studies have explored their effects on subsequent amounts of bark beetle caused tree mortality in interior ponderosa pine, Pinus ponderosa Dougl. ex P. & C. Laws. var. ponderosa. In this study, we examined bark beetle responses to creation of midseral (low diversity) and late-seral stages (high diversity) and the application of prescribed fire on 12 experimental units ranging in size from 76 to 136 ha. A total of 9500 (5.0% of all trees) Pinus and Abies trees died 2 years after treatment of which 28.8% (2733 trees) was attributed to bark beetle colonization. No significant difference in the mean percentage of trees colonized by bark beetles was found between low diversity and high diversity. The application of prescribed fire resulted in significant increases in bark beetle caused tree mortality (all species) and for western pine beetle, Dendroctonus brevico...

Trypanocidal potential of methanolic extract of Bridelia ferruginea benth bark in Rattus novergicus

Abstract: Full Length Research Paper Trypanocidal potential of methanolic extract of Bridelia ferruginea benth bark in Rattus novergicus J. T. Ekanem1, *O. M. Kolawole2, O. C. Abbah1 1Department of Biochemistry, Faculty of Basic Health Sciences, University of Uyo, Uyo, Nigeria. 2Department of Microbiology, University of Ilorin, Ilorin, Nigeria. *Corresponding author. E-mail: tomak74@yahoo.com. Tel: 2348060088495. Accepted 8 February 2008 Abstract An in vivo study of the trypanocidal potential of Bridelia ferruginea benth bark was investigated to determine its possible use against African sleeping sickness. Phytochemical screening revealed the presence of alkaloids, tannins, saponins, steroids and phlobatanins. Four groups of male albino rats weighing 220-250 g were used. The groups included the control, infected-untreated, uninfected-treated, and infected-treated. A daily dose of 20 mg/Kg body weight methanolic extract ofB. ferruginea benth bark was administered intraperitoneally at 72 h post-infection with Trypanosoma brucei brucei and parasitaemia was monitored daily. A continuous rise in parasite count was observed in the infected-untreated group. The infected-treated group showed a progressively lowered parasitamia on Days 5 to 8 post-infection, with percentage parasite reduction between 11 and 76%. Treatment also extended the lifespan for 2 days. Results also showed that treatment significantly ameliorated heamatological parameters that were studied. We suggest that methanolic extract of B. ferruginea benth bark can be useful in the management of African sleeping sickness. Key words: Bridelia ferruginea benth bark, Trypanosoma brucei, sleeping sickness, management.

Using Bark Char Codes to Predict Post-fire Cambium Mortality

Abstract: Cambium injury is an important factor in post-fire tree survival Measurements that quantify the degree of bark charring on tree stems after fire are often used as surrogates for direct cambium injury because they are relatively easy to assign and are non-destructive However, bark char codes based on these measurements have been inadequately tested to determine how well they relate to live or dead cambium Methods for assessing cambium injury through direct sampling have also been questioned as a potential factor for increasing tree mortality In this study we used data collected from 11 wildfires and 6 prescribed fires in California, Idaho, Montana, and Wyoming to develop a relationship between bark char codes and cambium status for 14 coniferous species Burned trees were assessed at groundline for bark char severity on each bole quadrant and then sampled at the center of each quadrant to determine cambium status (live or dead) We found that the moderate and deep bark char codes were strongly associated with dead cambium for thin-bark species: lodgepole pine (Pinus contorta), whitebark pine (P albicaulis), western white pine (P monticola), western redcedar (Thuja plicata), Engelmann spruce (Picea engelmannii), western hemlock (Tsuga heterophylla), and subalpine fir (Abies lasiocarpa) However, bark char codes were somewhat inaccurate in predicting cambium status of the thicker-bark species of white fir (Abies concolor), incense cedar (Calocedrus decurrens), ponderosa pine (Pinus ponderosa), Jeffrey pine (P jeffreyi), Douglas-fir (Pseudotsuga menziesii), western larch (Larix occidentalis), and sugar pine (P lambertiana) We also evaluated the effect of direct cambium sampling on ponderosa pine tree mortality in eastern Montana Mortality rates were equivalent for eastern Montana ponderosa pines with and without cambium sampling Our results support using bark char codes as surrogates for cambium sampling in tree species with thin bark, but bark char codes for thick-bark species, especially the moderate char code, are often not accurate fire-injury variables, as they do not correlate well with cambium status

Iridoids from the Bark of Alstonia scholaris

Abstract: Four new 11-noriridoids named scholareins A-D (1-4), along with three known derivatives, isoboonein (5). alyxialactone (6). and loganin (7), were isolated from EtOH extracts of the bark of Alstonia scholaris bv chromatographic methods. Their structures were identified by extensive mass-spectrometric and spectroscopic (especially 2D-NMR) experiments.

Wood fuel quality of two Salix viminalis stands fertilised with sludge, ash and sludge-ash mixtures

Abstract: This study assessed the effects of stand structure and fertilisation with wood ash and/or sludge on wood fuel quality of Salix viminalis. The relative proportions of bark and wood in 1-, 2- and 3-year-old shoot populations were determined. The concentrations of essential elements (N, P, K) and heavy metals (Cu, Zn, Cd, Ni) in bark and wood were used to assess the wood fuel quality in harvestable shoot biomass. Controlled field experiments were conducted on two newly harvested commercial short-rotation willow coppice fields. Five treatments were applied: sewage sludge at the maximum legally permitted amount; ash; two sludge–ash mixtures supplying the maximum and twice the maximum permitted sludge–ash amount; and a control receiving mineral nutrients only. The proportion of bark in the willow stands was decreasing with the age of the shoot population. The shoot population with few large stems, compared to that with many small stems, had a lower proportion of element-rich bark in the harvestable shoot biomass, meaning better quality of the wood fuel. Overall, wood fuel quality in terms of mineral concentrations was influenced by the age of the shoot population at harvest, stand structure, management practices (e.g. planting density, fertilisation) and site conditions (soil type, element availability). Our results imply that harvestable shoot biomass of willows grown as few large stems have better wood fuel quality, compared to harvestable shoot biomass of many small stems. Increased length of cutting cycle improves the wood fuel quality.