Analgesic activity of Peperomia pellucida aerial parts in mice

The methanol extract of Peperomia pellucida aerial parts, given orally at doses ranging from 70 to 210 mg/kg, showed a significant analgesic activity on acetic acid-induced writhing in mice.     

Soil microarthropod populations under natural and planted fallows in southwestern Nigeria

Microarthropods, such as soil mites (Acari) and springtails (Collembola), with body width between 0.08 mm and 0.5 mm play important roles in soil fertility maintenance through their regulatory activities in decomposition and nutrient turnover. Observations were made at IITA, Ibadan, southwestern Nigeria to evaluate the effects of natural regrowth of vegetation — mainly the shrub Chromolaena odorata — and three planted woody fallow species (Acacia leptocarpa, Senna siamea, and Leucaena leucocephala) on soil microarthropods in a degraded Alfisol. Populations of soil microarthropods were higher in the rainy season than the dry season, and populations were greater under natural fallow than for continuous cropping with maize (Zea mays) and cassava (Manihot esculenta). Populations of soil microarthropods were comparable under leucaena and natural fallow, but populations in the rainy season were 38% higher under senna than natural fallow and 36% higher under acacia than natural fallow. Regression analysis indicated that soil microarthropod population under fallow species was positively correlated with the lignin contents of leaf litter.This revised version was published online in November 2005 with corrections to the Cover Date.     

Equity Mechanisms in Traditional Forest Management Systems: A Case Study of Loita Forest in Kenya

Equity in forest resources access remains a key challenge. In Kenya this was exacerbated by the application of command and control management approaches. The introduction of Participatory Forest Management (PFM) in 1997 has started changing this scenario. The main objective of this study was to determine the equity mechanisms practiced under Traditional Community Based Forest Management (TCBFM), a traditional form of participatory forest management in Loita forest. An assessment of the impact of this management approach showed that equity and pro poor practices were inherent in Loita forest, where TCBFM was being implemented. The approach facilitated the poor to build up assets through relatives contributing to their livelihood assets. This was sustained through traditional support systems that are interwoven with forestry management. A majority of the community members interviewed perceived that the importance of the forest to household livelihood had been increasing since 1995. An increase in household assets since 1995 was associated with household participation in Traditional Community Based Natural Resources Management (TCBNRM). A majority (93%) of the households who were members of TCBNRM indicated grazing as the benefit. There was a general perception that participation in this form of PFM contributed to improvement of economic, physical, natural, human, social, and political capitals at the household and community levels.     

Chitin and glucans detected in the cell walls of Pythium dimorphum—an oomycetous fungus

With aid of fluorescein isothiocyanate (FITC) and gold-labelled lectins, together with antibodies against chitinase and β-1,3-glucanases, the spatial distribution of chitin and glucans in hyphal walls of Pythium dimorphum, a causative agent of root die-back disease of conifer seedlings was studied. Contrary to previous reports, this study revealed that chitin, a polymer of N-acetyl-d -glucosamine, is a component of the cell wall of this oomycetous fungus. However, compared with the other amino sugar, N-acetyl-galactosamine, it is not present in significant amounts. Ultrastructural and labelling studies demonstrated that the chitin region is embedded in or masked by glucan residues.     

The teleomorph of Chalara fraxinea,the causal agent of ash dieback

Ash dieback, caused by the pathogen Chalara fraxinea, is an emerging lethal disease of Fraxinus excelsior, threatening the host species in large parts of Europe. The ascomycete Hymenoscyphus albidus (Helotiaceae, Helotiales) was identified as the teleomorph of C. fraxinea by culturing from ascospores, morphological comparison and nuclear ribosomal internal transcribed spacer (ITS) sequencing.     

Soil DIC uptake and fixation in Pinus taeda seedlings and its C contribution to plant tissues and ectomycorrhizal fungi

Plants can acquire carbon from sources other than atmospheric carbon dioxide (CO(2)), including soil-dissolved inorganic carbon (DIC). Although the net flux of CO(2) is out of the root, soil DIC can be taken up by the root, transported within the plant, and fixed either photosynthetically or anaplerotically by plant tissues. We tested the ability of Pinus taeda L. seedlings exposed to (13)C-labeled soil DIC and two NH(4)(+) availability regimes to take up and fix soil DIC. We also measured the concentration and distribution of the fixed soil DIC within the plant and mycorrhizal tissues, and quantified the contribution of soil DIC to whole-plant carbon (C) gain. Seedlings exposed to labeled DIC were significantly enriched in (13)C compared with seedlings exposed to unlabeled DIC (6.7 versus -31.7 per thousand). Fixed soil DIC was almost evenly distributed between above- and belowground biomass (55 and 45%, respectively), but was unevenly distributed among tissues. Aboveground, stem tissue contained 65% of the fixed soil DIC but represented only 27% of the aboveground biomass, suggesting either corticular photosynthesis or preferential stem allocation. Belowground, soil DIC had the greatest effect (measured as (13)C enrichment) on the C pool of rapidly growing nonmycorrhizal roots. Soil DIC contributed approximately 0.8% to whole-plant C gain, and approximately 1.6% to belowground C gain. We observed a slight but nonsignificant increase in both relative C gain and the contribution of soil DIC to C gain in NH(4)(+)-fertilized seedlings. Increased NH(4)(+) availability significantly altered the distribution of fixed soil DIC among tissue types and increased the amount of fixed soil DIC in ectomycorrhizal roots by 130% compared with unfertilized seedlings. Increased NH(4)(+) availability did not increase fixation of soil DIC in nonmycorrhizal roots, suggesting that NH(4)(+) assimilation may be concentrated in ectomycorrhizal fungal tissues, reflecting greater anaplerotic demands. Soil DIC is likely to contribute only a small amount of C to forest trees, but it may be important in C fixation processes of specific tissues, such as newly formed stems and fine roots, and ectomycorrhizal roots assimilating NH(4)(+).     

Isolation of genes up-regulated by copper in a copper-tolerant birch (Betula pendula) clone

Suppression subtractive hybridization (SSH) was used to isolate genes differentially expressed following exposure to copper (Cu) in a naturally selected Cu-tolerant birch (Betula pendula Roth.) clone originating from a disused lead/zinc smelter. Of the 352 cDNA fragments initially isolated, 108 were up-regulated by Cu, of which 55 showed over twofold induction by macroarray analysis. Searches against protein databases (Blastx) and sequence analysis provided the tentative identity of 21 genes. Three fragments lacked homology to any sequences in the databases. Most of the identified genes are involved in cellular transport, regulation or cell rescue and defense. Several genes have not previously been reported to be up-regulated by Cu, e.g., plasma intrinsic protein 2, glutamine synthetase and multi-drug resistance-associated protein (MRP4). The expression of MRP4, a vacuolar sorting receptor-like protein and an unidentified gene was studied in more detail by quantitative real-time PCR. These genes showed stronger up-regulation by Cu in the roots and shoots of the Cu-tolerant birch clone compared with a less tolerant clone. Clear clonal differences in gene expression were observed, e.g., for the regulator of chromosome condensation family protein, DnaJ protein homolog, vacuolar sorting receptor-like protein and MRP4. These findings contribute to our understanding of Cu tolerance in birch, a pioneer plant in metal-contaminated soils.     

Effects of some lignans and neolignans on the development and excretion of Rhodnius prolixus.

The effects of six lignans and neolignans as inhibitors of ecdysis and on the water balance in fourth-instar larvae of Rhodnius prolixus were studied by oral, topical and continuous contact treatments. The main results may be summarised as follows: (i) burchellin, pinoresinol, sesamin, licarin A and nordihydroguaiaretic acid (NDGA) did not cause feeding inhibition at doses of 100 micrograms/ml blood; podophyllotoxin had no antifeedant effect but caused a high moulting inhibition and significant toxicity when applied either orally or topically; (ii) the highest ecdysis inhibitory effects were observed with pinoresinol and NDGA when applied orally at a dose of 100 micrograms/ml (58% and 50% of moulting inhibition, respectively); burchellin inhibited 30% of the moulting at this concentration; (iii) by topical treatment none of the compounds presented any influence on the moulting cycle; and (iv) podophyllotoxin and burchellin significantly reduced the excretion of the insect in 24 h; the other compounds had no effect on excretion. The implications of these findings in relation to the pertinent biological events in R. prolixus are discussed.     

Hydrothermal and organosolv pretreatments of poplar wood and wheat straw for saccharification by a Trichoderma viride cellulase

Summary Two types of processes have been applied for the pretreatment of lignocellulosic materials in order to render them easily degradable by the cellulase of Trichoderma viride. They were compared at different temperatures, with regard both to the residual dry mass and the improvement in accessibility to the enzyme complex. The latter was measured in terms of glucose liberated, which was quantified by HPLC. Hydrothermolysis proved more effective than the organosolv process for the pretreatment of wheat straw, and vice versa for poplar wood. In terms of the percentage of glucan enzymatically converted to glucose, yields up to 90% could be achieved.One of the authors (H.H.) would like to thank the Austrian Research Center Seibersdorf for granting a bursary. We are also grateful to Mr. Josef Huber for his kind assistance in preparing the three-dimensional plot     

Cost minimization through the use of taungya system in pulpwood plantation establishment

The costs and benefits of the use of three labour alternatives: direct permanent, direct casual and taungya labour in Gmelina arborea pulpwood plantation establishment in Nigeria were investigated. Results show that cost per hectare is lowest with taungya labour and highest with permanent labour with savings in cost of as much as 30% and 47% by taungya labour over casual and permanent labour respectively. The net present value per hectare of investment is highest when taungya labour is used and lowest and negative with permanent labour. Also, the internal rate of return of investment is highest with taungya labour and lowest with permanent labour. The net present values and internal rates of return for Gmelina plantations calculated for the three pulp and paper mills in Nigeria show the same trend in favour of taungya labour.